Cardiac valvular replacement devices: residual problems and innovative investigative technologies

The advancements in cardiac valvular replacement devices over the past 25 years have left residual problems with biological and mechanical prostheses. The extensive developments were introduced to reduce or eliminate valve-related complications, namely thromboembolism, anticoagulant-related hemorrhage, and structural failure, as weil as to optimize hemodynamic performance. Residual problems persist with both biological and mechanical prostheses. Structural failure of porcine and pericardial bioprostheses persists over time with leaflet degeneration and dystrophic calcification. Thrombus formation from blood stasis and the resultant thromboembolic phenomena despite anticoagulant management remain a continuing problem with mechanical prostheses. The innovative echnologies under investigation will likely significantly improve the clinical performance of both biological and mechanical prostheses.

Midterm survival of stented versus stentless valves: does concomitant coronary artery bypass grafting impact survival?

The purpose of this study was to examine the impact of concomitant coronary artery bypass grafting (CABG) and valve design on survival following aortic valve replacement (AVR) with stentless and stented bioprostheses. Survival data for 1798 patients undergoing AVR between 1991 and 1997 with either a stentless (Medtronic Freestyle = 700, Toronto SPV = 447; N = 1147) or stented (Hancock II = 224, Carpentier-Edwards SAV = 427; N = 651) valve were analyzed. Bivariable analyses using Kaplan-Meier survival curves and log-rank test were performed to compare survival probabilities by valve type. Multivariable stepwise Cox's proportional hazard models were used to control for potentially confounding variables. Concomitant CABG was performed in 41% of stentless and 46% of stented patients (P =.04). Survival probability at 5 years was 0.84 (95% CI = 0.81, 0.87) for stentless versus 0.79 (95% CI = 0.75, 0.83) for stented patients (P =.004). In the absence of concomitant CABG, survival was superior in stentless (0.84) over stented (0.80) patients, but these differences were not statistically significant (P =.053). In patients that underwent AVR with concomitant CABG, survival was significantly better in stentless patients (0.82) than in stented individuals (0.77, P =.049). The unadjusted hazard ratio for stented versus stentless was 1.44 (95% CI = 1.12, 1.86, P =.005). In the final Cox's proportional hazard model the variables that effected survival were valve type and age in decades. New York Heart Association class at the time of surgery had a marginal effect on survival. The data demonstrate improved midterm survival with stentless versus stented valves. Subgroup analysis suggests survival benefits of stentless valves may be greater in patients who undergo concomitant CABG surgery.

Medtronic Intact porcine bioprosthesis experience to twelve years

BACKGROUND

The Medtronic Intact porcine bioprosthesis was further evaluated to determine the influence of zero-pressure glutaraldehyde fixation on structural valve deterioration (SVD).

METHODS

From 1986 through 1996, at three Canadian centers, 1,272 patients had 1,296 procedures: 836 aortic valve replacement (AVR), 332 mitral valve replacement (MVR), 14 tricuspid valve replacement, 3 pulmonary valve replacement, and 111 multiple valve replacements. The mean age of the patient population was 67 years (range 9 to 91 years). The total follow-up was 8,011 patient-years (mean 6.2 years).

RESULTS

The late mortality (overall) was 4.8% and 6.7% per patient-year for AVR with or without concomitant procedures, respectively; and 4.7% and 10.4% per patient-year for MVR, respectively. There were 51 cases of SVD (AVR 22 of 836; MVR 23 of 332; pulmonary valve replacement 1 of 3; and multiple valve replacement 5 of 111). The actuarial freedom from SVD at 12 years for AVR was 94.3%+/-3.3% for patients aged 61 to 70 years and 97.7%+/-1.1% for those more than 70 years; for MVR actuarial freedom from SVD at 12 years was 93.7%+/-3.9% for patients more than 70 years. The actual freedom at 12 years from SVD for AVR was 92.4%+/-3.1% for patients aged 51 to 60 years, 96.1%+/-2.1% for those 61 to 70 years, and 98.4%+/-0.7% for those older than 70 years; for MVR actual freedom from SVD at 12 years was 89.6%+/-3.2% for patients 61 to 70 years and 96.6%+/-3.4% for those more than 70 years.

CONCLUSIONS

The Medtronic Intact porcine bioprosthesis, formulated with tissue preservation at zero-pressure fixation, has encouraging freedom from structural failure.

Carpentier-Edwards supraannular porcine bioprosthesis: second-generation prosthesis in aortic valve replacement

BACKGROUND

The Carpentier-Edwards supraannular porcine bioprosthesis experience for more than 18 years has been evaluated by actuarial and actual analysis to determine the clinical performance in aortic valve replacement.

METHODS

From 1981 to 1998, 1,823 patients (mean age 68.5 years, range 20 to 90 years) underwent 1,846 procedures. Previous coronary artery bypass was performed in 3.1% (56) and previous valve repair/replacement in 6.0% (110). Concomitant coronary artery bypass grafting was performed in 41.5% (756).

RESULTS

The overall valve-related complication rate was 4.5%/patient-year (567 patients) with a fatality rate of 0.9%/patient-year (110 patients). The patient survival, at 15 years, was 33.0%+/-3.7% for the 61 to 70 years age group and 13.5%+/-2.4% for the older than 70 years group. At 15 years, the overall actual, cumulative freedom from reoperation was 83.2%+/-1.4%, valve-related mortality was 88.0%+/-1.2%, and valve-related residual morbidity was 92.0%+/-0.8%. The actual freedom from structural valve deterioration at 15 years was 84.2%+/-2.8% for the 61 to 70 years group and 97.1%+/-0.9% for the older than 70 years group.

CONCLUSIONS

The Carpentier-Edwards porcine bioprosthesis provides excellent freedom from structural valve deterioration, and overall freedom from valve-related morbidity, mortality, and reoperation for aortic valve replacement for up to 15 years. The prosthesis is recommended for patients older than 70 years and for patients 61 to 70 years, especially when extended survival is not anticipated.

Medtronic Mosaic porcine bioprosthesis: midterm investigational trial results

BACKGROUND

The midterm clinical and hemodynamic performance of the Medtronic Mosaic porcine bioprosthesis was evaluated in a regulatory trial.

METHODS

In nine Canadian centers, 802 bioprostheses (560 aortic and 242 mitral) were implanted between September 1994 and April 1999 in patients with a mean age of 70 years.

RESULTS

Survival for aortic valve replacement at 4 years was 84.4%+/-3.1%. Freedom from valve-related or unexplained death was 95.6%+/-1.9%; structural valve deterioration, 100.0%; reoperation, 96.2%+/-1.7%; major thromboembolism, 96.1%+/-1.8%; and major antithrombotic-related hemorrhage, 96.4%+/-1.7%. Echocardiographic derived mean systolic gradient was 13.4 mm Hg at 4 years with an indexed effective orifice area of 0.7 to 0.8 cm2/m2. A significant decrease in left ventricular mass was shown over time in all valve sizes. Survival for mitral valve replacement at 4 years was 79.2%+/-6.8%. Freedom from valve-related or unexplained death was 96.5%+/-3.4%; structural valve deterioration, 100%; reoperation, 97.0%+/-3.2%; major thromboembolism, 95.7%+/-3.8%; and major antithrombotic-related hemorrhage, 95.0%+/-4.2%. Echocardiographically measured averaged mean diastolic gradient was 4.5 mm Hg.

CONCLUSIONS

The Medtronic Mosaic bioprosthesis is safe and effective in both the aortic and mitral positions. The valve has low gradients in both positions and excellent left ventricular mass regression in the patients with aortic valve replacement.

Hemodynamic comparison of second- and third-generation stented bioprostheses in aortic valve replacement

BACKGROUND

The hemodynamic performance of aortic replacement prostheses is of extreme importance. There is renewed interest in hemodynamics because of the influence of prosthesis-patient mismatch on left ventricular mass regression and the potential influence on survival.

METHODS

The hemodynamic performance of the second-generation Carpentier-Edwards supraannular porcine and pericardial (Perimount) bioprostheses and the third-generation Medtronic Mosaic porcine bioprosthesis were compared for mean gradient and effective orifice area index. The effective orifice area index of at least 0.85 cm2/M2 was considered as lack of prosthesis-patient mismatch. The study group included included 53 patients with Carpentier-Edwards supraannular porcine, 48 with pericardial, and 98 with Medtronic Mosaic porcine bioprostheses.

RESULTS

The mean gradients were not different between the prostheses by prosthesis size. The Medtronic Mosaic was not provided in size 19. The mean gradients for the prostheses, except in the very large sizes, were all double-digit values. The effective orifice area index was not different between the prostheses but there was a trend toward prosthesis-patient mismatch in smaller size prostheses.

CONCLUSIONS

There was no apparent hemodynamic advantage between porcine and pericardial bioprostheses in the aortic position.

Prediction of operative mortality after valve replacement surgery

OBJECTIVES

We sought to develop national benchmarks for valve replacement surgery by developing statistical risk models of operative mortality.

BACKGROUND

National risk models for coronary artery bypass graft surgery (CABG) have gained widespread acceptance, but there are no similar models for valve replacement surgery.

METHODS

The Society of Thoracic Surgeons National Cardiac Surgery Database was used to identify risk factors associated with valve surgery from 1994 through 1997. The population was drawn from 49,073 patients undergoing isolated aortic valve replacement (AVR) or mitral valve replacement (MVR) and from 43,463 patients undergoing CABG combined with AVR or MVR. Two multivariable risk models were developed: one for isolated AVR or MVR and one for CABG plus AVR or CABG plus MVR.

RESULTS

Operative mortality rates for AVR, MVR, combined CABG/AVR and combined CABG/ MVR were 4.00%, 6.04%, 6.80% and 13.29%, respectively. The strongest independent risk factors were emergency/salvage procedures, recent infarction, reoperations and renal failure. The c-indexes were 0.77 and 0.74 for the isolated valve replacement and combined CABG/valve replacement models, respectively. These models retained their predictive accuracy when applied to a prospective patient population undergoing operation from 1998 to 1999. The Hosmer-Lemeshow goodness-of-fit statistic was 10.6 (p = 0.225) for the isolated valve replacement model and 12.2 (p = 0.141) for the CABG/valve replacement model.

CONCLUSIONS

Statistical models have been developed to accurately predict operative mortality after valve replacement surgery. These models can be used to enhance quality by providing a national benchmark for valve replacement surgery.

Prosthesis-patient mismatch affects survival after aortic valve replacement

BACKGROUND

Surgeons traditionally avoid the use of "small" aortic prostheses because of the potential for residual left ventricular outflow tract obstruction and persistent transvalvular gradients. This study examines the ratio between prosthetic valve size and the body surface area (BSA) of patients undergoing aortic valve replacement (AVR). We sought to determine the effect of potential "prosthesis-patient" mismatch on long-term survival.

METHODS AND RESULTS

Follow-up was conducted on 2981 patients who underwent AVR with stented bioprostheses between 1976 and 1996. To account for differences between manufacturers' labeled valve sizes, we calculated the ratio between the prosthetic valve effective orifice area (EOA) and the patient's BSA (recorded for 2154 patients). The lowest decile in this cohort had a calculated EOA/BSA of <0.75 cm(2)/m(2) (Small group, n=227) compared with the control group (n=1927), in whom the EOA/BSA ratio was >0.75 cm(2)/m(2). Operative mortality was higher in the Small group (8% versus 5%, P:=0.03). Actuarial survival at 12 years was 50+/-5% in the Small group compared with 49+/-2% in the control group (P:=0.27). However, freedom from valve-related mortality was significantly lower in the Small group (75+/-5% versus 84+/-2%, P:=0.004). Cox regression analysis determined age and NYHA functional class to be the multivariate predictors of overall mortality, whereas advanced age and EOA/BSA <0.75 cm(2)/m(2) were found to be the predictors of valve-related mortality.

CONCLUSIONS

Prosthesis-patient mismatch results in significantly higher early and late mortality after bioprosthetic AVR. We recommend careful selection of stented bioprostheses to ensure an adequate ratio of EOA to BSA. An EOA/BSA ratio of >0.75 cm(2)/m(2) may avoid residual left ventricular outflow tract obstruction and persistent transvalvular gradients. Careful prosthesis-patient matching will improve both early and late survival after AVR.

CarboMedics mechanical prosthesis: performance at eight years

BACKGROUND AND AIM OF THE STUDY

The bileaflet St. Jude Medical mechanical prosthesis has been implanted for over 20 years. The purpose of this study was to evaluate the clinical performance of the bileaflet CarboMedics (CM) prosthesis, which was introduced in 1986.

METHODS

The CM prosthesis was implanted in 1,258 patients (709 males, 549 females; mean age 60.9 +/- 12.3 years) between 1989 and 1997. The prosthesis distribution was aortic valve replacement (AVR) 613; mitral valve replacement (MVR) 447; and multiple replacement (MR) 231. Coronary artery bypass (CAB) was performed in 334 (26.6%) patients; previous procedures had been performed in 346 (27.5%). The age distribution was <60 years (n = 527), 61-70 years (n = 424) and >70 years (n = 307). Risk factors assessed were age or age groups, gender, CAB, previous surgery, rhythm, valve position, status and NYHA functional class. The total follow up was 4,765.0 patient-years (pt-yr), and was 98.4% complete.

RESULTS

The early mortality rate was 5.6% (AVR 4.8%, MVR 3.7%, MR 11.5%). The late mortality rate was 3.7%/pt-yr (n = 174), and valve-related mortality 1.1%/pt-yr (n = 50). The total thromboembolism (TE) rate was 4.1%/pt-yr (n = 195) (p = NS by valve position); the major TE rate was 1.9%/pt-yr and fatal TE rate 0.31%/pt-yr (n = 15). The valve thrombosis rate was 0.31%/pt-yr (n = 15; 11 MVR, four MR). The fatal thrombosis rate was 0.06%/pt-yr (n = 3; two MVR, one MR). The hemorrhage rate was 2.7%/pt-yr (n = 128) and fatal hemorrhage rate 0.4%/pt-yr (n = 20). The reoperation rate was 1.0%/pt-yr (n = 46), fatal 0.1%/pt-yr (n = 5). The actuarial freedom from overall TE at eight years was 77.3 +/- 2.8%; major TE 88.5 +/- 1.6%, and hemorrhage 76.4 +/- 3.2% (all p = NS by valve position). There were no independent predictors of overall TE and TE exclusion of early events. The only predictor for TE major was status (emergency > urgent > elective). The actuarial freedom from valve-related mortality at eight years was 91.4 +/- 1.8% (p = NS by position) (actual freedom 93.0 +/- 1.3%). The actuarial freedom from valve-related reoperation was 91.1 +/- 2.4% (p <0.05; AVR > MVR and MR, MVR > MR) (actual freedom 92.2 +/- 2.7%). Overall survival rate at eight years was 68.2 +/- 2.3% (p <0.05; AVR > MVR and MR, MVR > MR).

CONCLUSION

The clinical performance of the CarboMedics mechanical prosthesis is satisfactory when implanted in the mitral, aortic and multiple positions.

Carpentier-Edwards porcine bioprostheses: clinical performance assessed by actual analysis

BACKGROUND AND AIM OF THE STUDY

The clinical performance of porcine bioprostheses for valve replacement has been evaluated for over three decades by actuarial analysis as the standard for reporting time-related results. Actual or cumulative incidence analysis provides a complementary method to determine the manifestations of valve-related complications due primarily to structural valve deterioration. Valve-related mortality and reoperation of porcine bioprostheses for aortic and mitral valve replacement was compared by actuarial and actual methodology.

METHODS

The Carpentier-Edwards porcine bioprostheses were implanted between 1975 and 1995 as 2,237 aortic valve replacements (AVR) and 1,582 mitral valve replacements (MVR). Coronary artery bypass was performed in 36.4% of AVR, and 30.6% of MVR. Fatal valve-related complications occurred in 7.6% of AVR and 11.3% of MVR. The cumulative follow up was 14,810 patient-years (mean 6.6 years) for AVR and 9,718 patient-years (mean 6.1 years) for MVR.

RESULTS

Patient survival, and actuarial and actual freedom from valve-related mortality and valve-related reoperation was reported at 15 years. For AVR, survival in the 61-70 years age group was 30.9%, freedom from valve-related mortality was 79.3% and 86.9% respectively, and freedom from valve-related reoperation 79.0% and 88.1% respectively. For AVR, survival in the >70 years age group was 18.1%, freedom from valve-related mortality 72.8% and 84.9% respectively, and freedom from reoperation 86.3% and 96.1% respectively. For MVR, survival in the 61-70 years age group was 16.1% at 15 years, freedom from valve-related mortality was 59.5% and 79.5% respectively, and freedom from valve-related reoperation 32.6% and 71.0% respectively. For MVR, survival in the >70 years age group was 2.8% at 15 years, valve-related mortality was 26.1% and 82.0% respectively, and freedom from valve-related reoperation 83.4% and 93.3% respectively.

CONCLUSION

The actual freedom from valve-related mortality and valve-related reoperation (primarily from structural valve deterioration), provides further evidence to consider porcine bioprostheses for AVR in patients aged >60 years, and for MVR in patients aged >70 years. The freedom from valve-related mortality supports the use of porcine bioprostheses for MVR in patients aged 61-70 years. Patient survival is influenced to the greatest extent by factors other than valve-related mortality.

Prosthesis-patient mismatch: hemodynamic comparison of stented and stentless aortic valves

Several centers have reported excellent clinical performance of stentless aortic xenografts. This study reports a hemodynamic comparison of the Medtronic Freestyle stentless and Mosaic stented valves. The prosthetic hemodynamics at discharge and 1 year after insertion in 95 patients who underwent aortic valve replacement with the Freestyle stentless bioprosthesis at Southern California Kaiser Permanente Medical Center were compared retrospectively with 115 unmatched individuals who received the Mosaic stented valve at the University of British Columbia. As assessed by echocardiography, there were no differences in the mean transvalvular gradient, effective orifice area (EOA), or EOA indexed to body surface area (EOAI) at discharge between the two groups. However, after 1 year, all corresponding Freestyle valve sizes had larger EOAs and lower gradients. Furthermore, fewer patients receiving Freestyle xenografts had prosthesis-patient mismatch (19% vs. 64%, P<.001) as defined by EOAI <0.85 cm2/m2. Although the Mosaic stented valve provides comparable immediate hemodynamic performance after implantation, there is significant improvement with the Freestyle bioprosthesis in terms of gradient, EOA, and prosthetic-patient mismatch at 1 year.

Actuarial versus actual freedom from structural valve deterioration with the Carpentier-Edwards porcine bioprostheses

BACKGROUND

The clinical performance of porcine bioprostheses for valve replacement surgery has been evaluated for over three decades by actuarial analysis as the standard for reporting time-related results. The incidence of structural valve deterioration (SVD) is used for the selection of prostheses for various subsets of patients. Actual or cumulative incidence analysis may provide a superior method to determine durability of bioprostheses.

OBJECTIVE

To compare actuarial versus actual methodology in determining the durability of porcine bioprostheses for aortic (AVR) and mitral valve replacement (MVR).

PATIENTS AND METHODS

Carpentier-Edwards porcine bioprostheses were implanted between 1975 and 1995 in 2237 AVR and 1582 MVR. The mean age for AVR patients was 65.4+/-12 years and for MVR patients 61.7+/-12 years. The cumulative follow-up for AVR was 14,810 years (mean 6.6+/-4.7) and for MVR 9718 years (mean 6. 1+/-4.5).

RESULTS

For AVR the actual freedom from SVD was 87.4+/-2. 0% and 95.6+/-1.8% in those aged 61 to 70 years and more than 70 years, respectively; the actuarial freedom was 75.9+/-4.2% and 82. 3+/-7.9%, respectively. For MVR the actual freedom from SVD was 69. 4+/-2.5% and 92.9+/-1.9% for those aged 61 to 70 years and more than 70 years, respectively; the actuarial freedom was 25.5+/-5.7% and 79. 5+/-6.0%, respectively. Predictors of freedom from SVD for AVR were identified as advancing age, falling into the age groups 61 to 70 and those older than 70 years, and intermediate valve sizes; predictors for MVR were advancing age and age older than 70 years.

CONCLUSIONS

Comparison of methods of durability assessment revealed that actual freedom from SVD supports porcine bioprostheses for AVR in patients more than 60 years of age and for MVR in patients more than 70 years of age. This evaluation with experience to 15 years supports the indications for use of porcine bioprostheses.

Bileaflet mechanical prostheses performance in mitral position

OBJECTIVE

The experience with the Carbomedics (CM) and the St. Jude Medical (SJM) bileaflet mechanical prostheses was evaluated to determine thromboembolic and hemorrhagic complications and predictive risk factors.

METHODS

From 1989 to 1994, a total of 625 patients had mitral valve replacement (CM, 240; SJM, 385); 32.5% (203), concomitant procedures and 32.8% (205), previous cardiac surgery, primarily valve replacement procedures.

RESULTS

The pre-operative variables did not distinguish the populations, except for previous surgery CM 37.9% and SJM 29.6% (P < 0.05). The pre-operative variables (type of prostheses, cardiac rhythm, coronary artery bypass, NYHA III/IV, advancing age, gender, urgency status and previous surgery) were not predictive of overall thromboembolism (TE), major TE, minor TE, prosthesis thrombosis and hemorrhage (P not significant; P = NS). The linearized rate of total TE events for overall MVR was 5.0%/patient-year (CM 4.4; SJM 5.4). The < or = 30 day major crude rate was 0.44%, while the > 30 day late major event rate was 2.0%/patient-year. Of the total TE events 91% of < or = 30 days and 75%, > 30 days had an INR < 2.5 at or immediately prior to the event. The thrombosis rate (included in TE events) was 0.63%/patient-year (ten events, four managed successfully with thrombolysis, five successfully with reoperation, and one fatality identified at autopsy). The freedom, at 5 years, from major/fatal TE, thrombosis and hemorrhage from anticoagulation was 88.2%, and 89.5% exclusive of early events.

CONCLUSIONS

This non-randomized prospective observational evaluation of the CarboMedics and St. Jude Medical prostheses has not revealed any differentiation in performance of the prostheses. The study serves as a single institution experience with the potential for future comparative evaluation.

Risk stratification for cardiac valve replacement. National Cardiac Surgery Database. Database Committee of The Society of Thoracic Surgeons

BACKGROUND

The Society of Thoracic Surgeons National Database Committee is committed to risk stratification and assessment as integral elements in the practice of cardiac operations. The National Cardiac Surgery Database was created to analyze data from subscribing institutions across the country. We analyzed the database for valve replacement procedures with and without coronary artery bypass grafting to determine trends in risk stratification.

METHODS

The database contains complete records of 86,580 patients who had valve replacement procedures at the participating institutions between 1986 and 1995, inclusive. The 1995 harvest of data was conducted in late 1996 and available for evaluation in 1997. These records were used to conduct an in-depth analysis of risk factors associated with valve replacement and to provide prediction of operative death by using regression analysis. Regression models were made for six subgroups.

RESULTS

Adverse patient risk factors, including diabetes, hypertension and reoperation, but not ventricular function, increased over time. There were trends with regard to increasing age of the various population subsets. The types of prostheses used remained similar over time, with more mechanical prostheses than bioprostheses used for both aortic and mitral valve replacement. There was a trend toward increased use of bioprostheses in aortic replacements and decreased use in mitral replacements between 1991 and 1995 than between 1986 and 1990. The mortality rate was determined by patient subset for primary operation and reoperation and by urgency status. The modeling showed that the predicted and observed mortality correlated for all age groups and within patient subsets.

CONCLUSIONS

Risk modeling is a valuable tool for predicting the probability of operative death in any individual patient. This large, multiinstitutional database is capable of determining modern operative risk and should provide standards for acceptable care. The study illustrates the importance of risk stratification for early death both for the patient and the surgeon.

Bileaflet mechanical prostheses for aortic valve replacement in patients younger than 65 years and 65 years of age or older: major thromboembolic and hemorrhagic complications

OBJECTIVE

To determine major thromboembolic and hemorrhagic complications and predictive risk factors associated with aortic valve replacement (AVR), using bileaflet mechanical prostheses (CarboMedics and St. Jude Medical).

DESIGN

A case series.

SETTING

Cardiac surgical services at the teaching institutions of the University of British Columbia.

PATIENTS AND METHODS

Patients 2 age groups who had undergone AVR between 1989 and 1994 were studied. Group 1 comprised 384 patients younger than 65 years. Group 2 comprised 215 patients 65 years of age and older.

RESULTS

The linearized rates of major thromboembolism (TE) occurring after AVR were 1.54%/patient-year for group 1 and 3.32%/patient-year for group 2; the rates for major TE occurring more than 30 days after AVR were 1.13%/patient-year for group 1 and 1.55%/patient-year for group 2. The crude rates for major TE occurring within 30 days of AVR were 1.04% for group 1 and 3.72% for group 2. The death rate from major TE in group 1 was 0.31%/patient-year and in group 2 was 0.88%/patient-year. Of the major TE events occurring within 30 days, 100% of patients in both age groups were inadequately anticoagulated at the time of the event, and for events occurring more than 30 days after AVR, 45% in group 1 and 57% in group 2 were inadequately anticoagulated (INR less than 2.0). The overall linearized rates of major hemorrhage were 1.54%/patient-year for group 1 and 2.21%/patient-year for group 2. There were no cases of prosthesis thrombosis in either group. The mean (and standard error) overall freedom from major TE for group 1 patients at 5 years was 95.6% (1.4%) and with exclusion of early events was 96.7% (1.3%); for group 2 patients the rates were 90.0% (3.2%) and 93.7% (3.0%), respectively. The mean (and SE) overall freedom from major and fatal TE and hemorrhage for group 1 patients was 90.1% (2.3%) and with exclusion of early events was 91.2% (2.3%); for group 2 patients the rates were 87.9% (3.1%) and 92.5% (2.9%), respectively. The 5-year rate for freedom from valve-related death for group 1 patients was 96.3% (2.1%) and for group 2 patients was 97.2% (1.2%).

CONCLUSION

The thromboembolic and hemorrhagic complications after AVR with bileaflet mechanical prostheses occur more frequently and result in more deaths in patients 65 years of age and older than in patients years younger than 65 years.

Carpentier-Edwards standard and supraannular porcine bioprostheses: comparison of technology

BACKGROUND

Performance with regard to structural valve deterioration (SVD) with the Carpentier-Edwards standard (CE-S) and supraannular (CE-SAV) (Baxter Healthcare Corp, Irvine, CA) porcine bioprostheses was evaluated to determine whether progress in reduction of structural failure has been achieved with technological changes.

METHODS

The CE-S was implanted during 567 aortic valve replacement (AVR) and 486 mitral valve replacement (MVR) procedures, and the CE-SAV was implanted during 1,670 AVR and 1,096 MVR procedures. The failure mode of early stent dehiscence with the CE-SAV prosthesis, thought to be controlled by manufacturing changes in 1986 and 1987, supported comparison of the CE-SAV with censored cases of stent dehiscence. Stent dehiscence accounted for only 1.2% (1 of 81) and 14.1% (29 of 205) of AVR and MVR CE-SAV failures, respectively.

RESULTS

The only difference for AVR for freedom from SVD occurred in the 21- to 40-year age group at 15 years and was 68% for the CE-SAV and 31% for the CE-S (p<0.05). In the 61- to 70-year age group, freedom from SVD at 15 years was 76% for the CE-S and 84% for the CE-SAV; for the 71-year or higher age group, freedom from SVD was 89% and 95%, respectively (p = NS). For MVR freedom from SVD was different only in the 71-year or higher age group and was 90% for the CE-S and 59% for the CE-SAV (p<0.05). Freedom from SVD was reduced but was similar (p = NS) for the other age groups. For AVR the actual freedom from SVD at 15 years for the CE-S and CE-SAV was, respectively, 79% and 72% for the 51- to 60-year age group, 86% and 91% for the 61- to 70-year age group, and 98% and 98% for the 71-year or higher age group. For MVR, these rates were, respectively, 69% and 75% for the 61- to 70-year age group and 96% and 89% for the 71-year and higher age group.

CONCLUSIONS

The technologic advancements made in the second-generation CE-SAV bioprosthesis to reduce the incidence of structural failure have not uniformly been successful. The actual freedom from SVD provides evidence for implantation of porcine bioprostheses for AVR in age groups 61 to 70 years and 71 years or higher and for MVR in the age group 71 years or higher.

Medtronic mosaic porcine bioprosthesis satisfactory early clinical performance

BACKGROUND

The Medtronic (Minneapolis, MN) Mosaic porcine bioprosthesis is an investigational prosthesis which incorporates zero-pressure fixation, aortic root predilation, low profile stent, and alpha oleic acid antimineralization treatment.

METHODS

From September 1994 to August 1996, 289 patients (mean age 70 years, range, 28 to 88 years) had 227 (78.5%) aortic valve replacements and 62 (21.5%) mitral valve replacements. Concomitant procedures were performed in 61.2% (139) of aortic valve replacements and 54.8% (34) of mitral valve replacements. Of the aortic valve replacement group 70 (30.8%) were in the 61 to 70 age group and 134 (59.0%) were 71 years or older. Of the mitral valve replacements, 23 (37.1%) were 61 to 70 years and 30 (48.4%) 71 years or older.

RESULTS

The early mortality, overall, was 4.2% (12 of 289); for aortic valve replacement it was 4.0% (9) and for mitral valve replacement it was 4.8% (3). The late mortality for aortic valve replacement was 2.6% per patient-year (3 events, 1.3% of total) and for mitral valve replacement it was 3.3% per patient-year (one event, 1.6% of total). The reoperative rate for aortic valve replacement was 3.0% per patient-year (4), while there were no mitral valve replacement reoperations. The freedom from major thromboembolism was 97.3%+/-1.6% for aortic valve replacement and 94.7%+/-3.0% for mitral valve replacement at 1 to 1.5 years. The freedom from reoperation was 96.7%+/-1.7% for aortic valve replacement; there was no reoperation for mitral valve replacement. There were no cases of structural valve deterioration. In the aortic position the mean systolic gradient was low, approximately 11 mm Hg, across all sizes (range 8 to 12 mm Hg at 3 months and 10 to 13 mm Hg at 12 months). In the mitral position the mean diastolic gradient was approximately 5 mm Hg (range, 2 to 6 mm Hg) for all sizes 25 to 31 mm at the early and 1 year follow-up echocardiographic assessment.

CONCLUSIONS

The early clinical performance and in vivo hemodynamics are encouraging.

Carpentier-Edwards standard porcine bioprosthesis: a 21-year experience

BACKGROUND

The Carpentier-Edwards standard porcine bioprosthesis experience to 21 years has been evaluated to determine the influence of structural valve deterioration by valve position in various age groupings.

METHODS

From 1975 to 1988, 1,181 patients had the prosthesis implanted in 1,198 procedures. The mean age of the population was 57.9+/-12.5 years (range, 21 to 85 years). Aortic valve replacement was performed in 564 patients (47.8%); mitral valve replacement, 478 (40.5%); and multiple valve replacement, 132 (11.2%). Concomitant procedures were performed in 337 patients (28.5%), and 140 (11.9%) had previous operations.

RESULTS

The early mortality was 8.1% (97), only 0.4% (5) of which were valve-related. The total follow-up was 10,405 years (mean, 8.8+/-5.2 years). The late mortality was 5.7%/patient-year (591), with the valve-related component 1.6%/patient-year (168) with a 13% reoperative mortality (56). The linearized rate of structural valve deterioration was 3.8%/patient-year (395), with overall complications of 7.1%/patient-year (737). The overall survival at 20 years was 17.2%+/-3.1% (p < 0.05; aortic valve replacement greater than mitral valve replacement or multiple valve replacement). The freedom from structural valve deterioration was, at 18 years, 25.8%+/-2.8% overall, AVR 40.6%+/-4.2%, and MVR 8.5%+/-3.4% (p < 0.05, aortic valve replacement greater than mitral valve replacement or multiple valve replacement). The freedom from structural valve deterioration for aortic valve replacement was, at 15 years, for patients older than 70 years, 82.9%+/-9.1%; 61 to 70 years, 73.2%+/-4.7%; 51 to 60 years, 58.8%+/-5.4%; 41 to 50 years, 41.7%+/-8.2%; and 21 to 40 years, 25.5%+/-7.8%. The freedom from structural valve deterioration for mitral valve replacement was, at 15 years, for patients older than 70 years, 89.8%+/-7.6%; 61 to 70 years, 22.8%+/-6.3%; 51 to 60 years, 26.3% +/- 5.7%; 41 to 50 years, 11.7%+/-5.6%; and 21 to 40 years, 7.0%+/-4.7%.

CONCLUSIONS

The prosthesis is recommended for aortic valve replacement for patients older than 70 years and for patients 61 to 70 years (when extended longevity is not anticipated) and for mitral valve replacement for patients older than 70 years.

Mitroflow pericardial bioprosthesis experience in aortic valve replacement > or =60 years of age

BACKGROUND

The Mitroflow pericardial bioprosthesis (model 11), a second-generation pericardial prosthesis, has clinical performance assessment to 10 years. The authors previously recommended the prosthesis for aortic valve replacement in patients 70 years or older. The purpose of the current assessment is to report on performance in patients 60 years or older undergoing aortic valve replacement.

METHODS

This bioprosthesis was implanted in 161 patients (mean age, 69.5+/-6.3 years; range, 60 to 94 years) with aortic valve replacement from 1982 to 1992. There were 84 patients 60 to 69 years (mean, 64.5+/-3.1 years) and 77 patients 70 years or older (mean, 74.8+/-4.3 years). Of the total population, concomitant procedures were performed in 63 patients (39.1%); of these, coronary artery bypass grafting was performed in 39 (24.2%).

RESULTS

The early mortality was 4.8% (4 patients) for the 60 to 69-year age group and 10.4% (8) for those 70 years or older (not significant). The late mortality was 4.4%/patient-year (27) for those 60 to 69 years and 6.9%/ patient-year (35) for those 70 years or older (not significant). The patient survival for those 60 to 69 years was 58.0%+/-6.3% and for those 70 years or older, 45.3%+/-5.9% at 10 years (p < 0.05). The valve-related mortality for those 60 to 69 years was 0.82%/patient-year (5) and for those 70 years or older, 1.58%/patient-year (8) (not significant). The reoperation rate for those 60 to 69 years was 3.29%/patient-year (20) and for those 70 years or older, 1.0%/patient-year (5) (p < 0.05). The structural valve deterioration rate for those 60 to 69 years was 3.13%/ patient-year (19) and for those 70 years or older, 1.2%/ patient-year (6) (p < 0.05).

CONCLUSIONS

The Mitroflow pericardial bioprosthesis remains recommended for aortic valve replacement in patients 70 years and older.

Medtronic intact porcine bioprosthesis: 10 years' experience

BACKGROUND

The Medtronic Intact porcine bioprosthesis experience was evaluated over a period of 10 years to determine the influence of structural valve deterioration by valve position in various age groupings.

METHODS

From 1986 to 1996 inclusive, at three centers, 1,272 patients had the prosthesis implanted in 1,296 procedures. The mean age of the population was 67 years (range, 9 to 91 years). There were 836 aortic valve replacements (AVR) (64.5%), 333 mitral valve replacements (MVR) (25.7%), and 110 multiple valve replacements (MR) (8.5%).

RESULTS

The early mortality was 7.3% (94 of 1,296 procedures). The early mortality with concomitant procedures (primarily coronary artery bypass grafting) was 9.8% (52 of 528) and without, 5.5% (42 of 768). The late mortality was 4.25%/patient-year. The linearized rate of major thromboembolism was 0.86%/patient-year. The rate of reoperation was 1.19%/patient-year and valve-related mortality, 1.06%/patient-year. There were 36 cases of structural valve deterioration for aortic valve replacement (16), mitral valve replacement (15), tricuspid valve replacement (2), and multiple valve replacement (3). The freedom from structural valve deterioration for aortic valve replacement was in patients 21 to 40 years, 62.5%+/-25.8% at 7 years; 41 to 50 years, 75.0%+/-15.3% at 7 years; 51 to 60 years, 91.0%+/-4.5% at 8 years; 61 to 70 years, 98.7%+/-0.7% at 10 years; and older than 70 years, 98.3%+/-1.0% at 10 years (p < 0.05). The freedom from structural valve deterioration for mitral valve replacement was for patients 41 to 50 years, 91.7%+/-8.0% at 7 years; 51 to 60 years, 85.9%+/-9.9% at 8 years; 61 to 70 years, 86.3%+/-6.8% at 8 years; and older than 70 years, 93.9%+/-4.8% at 8 years (not significant).

CONCLUSIONS

The Medtronic Intact porcine bioprosthesis has acceptable freedom from structural valve deterioration in both the aortic and mitral positions approaching 10 years of evaluation.

Carpentier-Edwards supraannular porcine bioprosthesis evaluation over 15 years

BACKGROUND

The Carpentier-Edwards supraannular porcine bioprosthesis experience during 15 years has been evaluated to determine the incidence of structural valve deterioration by valve position in various age groupings.

METHODS

From 1981 to 1995, 2,943 patients older than 20 years had the prosthesis implanted in 3,024 procedures. The mean age of the population was 65.5+/-11.9 years (range, 21 to 89 years). Aortic valve replacement was performed in 1,657 patients (54.8%); mitral valve replacement, 1,092 (36.1%); multiple valve replacement, 253 (8.3%); pulmonary valve replacement, 2 (0.1%); and tricuspid valve replacement, 20 (0.7%). Concomitant procedures were performed in 1,332 patients (45.3%), and 352 (12.0%) had previous procedures.

RESULTS

The early mortality was 8.9% (270), only 0.4% (11) valve-related. The total follow-up was 17,471 years (mean, 5.9+/-4.1 years). The late mortality was 5.2%/ patient-year (901) with the valve-related component 1.0%/patient-year (171). The reoperation rate was 2.1%/ patient-year (369) with 4.3% mortality (16). The linearized rate of structural valve deterioration was 2.0%/patient-year (341), and overall complications, 5.9%/patient-year (1,019). The overall survival, at 15 years, was 31.1%+/2.8% (p < 0.05; aortic valve replacement greater than mitral valve replacement or multiple valve replacement). The freedom from structural valve deterioration for aortic valve replacement was, at 12 years, for patients older than 70 years, 95.3%+/-2.7%; 61 to 70 years, 92.9%+/-2.1%; 51 to 60 years, 70.1%+/-5.3%; 41 to 50 years, 60.0%+/-8.8%; and 21 to 40 years, 75.7%+/-7.3%. The freedom from structural valve deterioration for mitral valve replacement was, at 12 years, for patients older than 70 years, 66.1%+/-9.7%; 61 to 70 years, 53.1%+/-4.7%; 51 to 60 years, 52.6%+/-5.5%; 41 to 50 years, 39.3%+/-6.9%; and 21 to 40 years, 42.1%+/-9.4%.

CONCLUSIONS

The prosthesis is recommended for aortic valve replacement for patients older than 70 years and for patients 61 to 70 years (when extended longevity is not anticipated) and for mitral valve replacement for patients older than 70 years (when extended longevity is not anticipated).

Quality of life in patients with bioprostheses and mechanical prostheses. Evaluation of cohorts of patients aged 51 to 65 years at implantation

BACKGROUND

The purpose of this study was 3-fold: to compare the quality of life (QOL) in age- and sex-matched patients who received biological and mechanical prosthetic valves in isolated aortic valve replacement, to compare the QOL of patients with aortic valve replacement with the general population, and to compare patients with biological and mechanical prostheses with certain valve-specific questions and relate these responses to overall QOL.

METHODS AND RESULTS

Patient-perceived QOL was evaluated in 200 patients who were sampled from a population of 420 patients (age range 51 to 65 years) who underwent isolated aortic valve replacement in the period of 1986 to 1996. One hundred of the sampled patients had a mechanical valve inserted and an equal number had porcine bioprostheses. Three survey instruments were used to examine perceived QOL: the SF-12 form, a 7-valve specific question form, and the Lamy Smiley Faces form. The response to the questionnaires was 89.5% (179 patients). Patients with mechanical valves were more bothered by valve sounds (P < 0.01) and had a negative correlation (P < 0.01) between valve sound and QOL on the mental scale only. Patients with biological valves were more fearful of the need for reoperation (P < 0.01), but there was no correlation between fear and QOL. The mechanical valve group had a negative correlation (P < 0.01) between fear of reoperation and QOL on both the mental and physical scales. There was no difference between the 2 cohorts with respect to fear of valve failure. Patients with mechanical valves were more concerned about frequency of medical visits and blood tests (P < 0.01) as well as the possibility of anticoagulant-related bleeding events (P < 0.01). QOL was equivalent between the 2 groups and to the general population for the same age group. Ninety-seven percent of the patients indicated they would make the same surgical decision again with regard to valve replacement; there was no difference between the 2 valve groups on this question.

CONCLUSIONS

Patient-perceived QOL is similar between patients with aortic mechanical and biological valve replacement in the studied age group and comparable to the general population of similar age. Although certain valve-specific differences exist between the 2 prosthetic types, these differences do not appear to affect overall QOL as described by these patients.

Strategies of myocardial protection for operation in chronic model of cyanotic heart disease

BACKGROUND

Cyanotic congenital hearts have an increased susceptibility to ischemia and subsequent reperfusion. The role of platelet-activating factor antagonism and mechanical neutrophil depletion with leukocyte-depleting filters for control of ischemia-reperfusion injury was assessed in corrective surgical procedures for cyanotic heart disease.

METHODS

A swine model of cyanotic heart disease was evaluated with three study groups: a control group; a group given a platelet-activating factor antagonist (PAFA group); and a group with leukocyte-depleting filtration (LDF group). The cyanotic model was created with a left atrial appendage-pulmonary artery fistula with peripheral banding through a left anterior thoracotomy in weanling swine. The experimental procedure was performed 5 to 7 weeks later when body weight was greater than 20 kg and oxygen saturation was 85% or less. The corrective procedure was performed through a median sternotomy on cardiopulmonary bypass with repair of the shunt. Myocardial protection was accomplished with hypothermic blood-crystalloid (4:1) cardioplegia; the period of ischemic arrest was 90 minutes. In the PAFA group, the platelet-activating factor antagonist CV-6209 was delivered intravenously 15 to 20 minutes before aortic cross-clamping. In the LDF group, Pall leukocyte-depleting filters were used in the CPB arterial line. Hemodynamic data were taken before operation and 10 and 30 minutes after CPB with impedance ventriculography.

RESULTS

There were four deaths in the control group within 30 minutes after CPB; all animals in the treated groups survived longer than 60 minutes (p < 0.05). The ventricular assessment of end-systolic elastance revealed superior performance in the LDF group 30 minutes after CPB compared with the control group (p < 0.05) (controls, 4.0+/-9; PAFA group, 6.5+/-3.7; and LDF group, 12.0+/-4.6).

CONCLUSIONS

Both leukocyte-depleting filters and platelet-activating factor antagonism provided myocardial protection, and the filters afforded superior postoperative myocardial contractility.

Multiple mechanical valve replacement surgery comparison of St. Jude Medical and CarboMedics prostheses

OBJECTIVE

The experience with the St. Jude Medical (SJM) and CarboMedics (CM) bileaflet mechanical prostheses was evaluated to determine thromboembolic and hemorrhagic complications and predictive risk factors.

METHODS

From 1989 to 1994, a total of 246 patients had multiple valve replacement (SJM, 140; CM, 106); concomitant procedures 20.3% (50) [coronary artery bypass 10.6% (26)] and 53.7% (132) previous cardiac surgery, primarily valve replacement procedures. The pre-operative variables [coronary artery disease, previous cardiovascular surgery, concomitant procedures, valve lesion (except mitral stenosis), status, atrial fibrillation, and NYHA III/IV] did not distinguish the prosthesis-type (pNS).

RESULTS

The prosthesis-type and the pre-operative variables, including atrial fibrillation, were not predictive of overall thromboembolism (TE). The linearized rate of total TE events for overall multiple replacements (MR) was 5.4%/patient-year (minor, 2.52; major 2.85); the total TE for CM and SJM was 5.4%/patient-year, respectively. The < or = 30 day major TE crude rate was 0.82%, while the > 30 day major event rate was 2.7%/patient-year. Of the total (major and minor) TE events 100% (3) of < or = 30 days and 72% (29), > 30 days had an INR < 2.5 at or immediately prior to the event. The thrombosis rate (included in total TE events) was 0.67%/patient-year (4 events, 100% INR < 2.5). Of the various TE event categories the prosthesis-types (CM and SJM) were not differentiated (pNS). The freedom, at 5 years, from major/fatal TE, thrombosis and hemorrhage from anticoagulation was 89.3 +/- 3.8% for CM and 87.9 +/- 3.7% for SJM and, 91.3 +/- 3.5% and 89.3 +/- 3.7%, respectively, (pNS) exclusive of early events.

CONCLUSIONS

The performance of the CarboMedics and St. Jude Medical prostheses in multiple valve replacement surgery in this non-randomized prospective study revealed no significant differences in performance with regard to thromboembolic and hemorrhagic complications.

Bileaflet mechanical prostheses in mitral and multiple valve replacement surgery: influence of anticoagulant management on performance

BACKGROUND

The St. Jude Medical (SJM) mechanical prosthesis has been the predominant mechanical prosthesis worldwide since its introduction in 1977. The CarboMedics (CM) mechanical prosthesis, also a bileaflet pyrolite carbon prosthesis, was introduced in 1986 and was approved by the Food and Drug Administration of the United States in 1993. The experience of the two prostheses was evaluated in a parallel, nonrandomized study commencing with the CM investigational study in 1989.

METHODS AND RESULTS

The clinical performance of the two prostheses was evaluated in accordance with the Guidelines for Reporting Morbidity and Mortality After Cardiac Valvular Operations. The CM prosthesis was implanted in 239 mitral valve replacements (MVR) and 106 multiple valve replacements (MR), and the SJM prosthesis was implanted in 379 MVR and 137 MR. The CM and SJM populations were not distinguished within MVR and MR for mean age, previous surgery, concomitant surgery, mean follow-up, and late mortality (P=NS). The linearized occurrence rate for the combined experience for major thromboembolic and hemorrhage events >30 days was 3.4% of patients per year for MVR (inclusive of cerebral thromboembolism reversible, major; systemic; thrombosis; and fatal; and major systemic hemorrhage) and for MR was 3.9% of patients per year (P=NS between prostheses by position). The major crude event rate for < or =30 days was 1.3% for MVR and 1.2% for MR (P=NS between prostheses by position). The inadequacy of anticoagulation (as determined by international normalized ratio 2.5) for all thromboembolic events (major and minor) < or =30 days was 93%, and that for >30 days was 75%. The freedom from major thromboembolism for MVR at 3 years was 92.7+/-1.9% for CM and 94.0+/-1.5% for SJM; for MR, it was 94.2+/-3.0% for CM and 93.5+/-2.5% for SJM (P=NS). The freedom from major thromboembolism exclusive of early events for MVR at 3 years was 94.4+/-1.8% for CM and 94.8+/-1.4% for SJM, and for MR, it was 94.2+/-3.0% for CM and 95.0+/-2.2% for SJM (P=NS). The freedom from major thromboembolism and hemorrhage for prostheses (CM and SJM) by valve positions (MVR and MR) was also indistinguishable (P=NS).

CONCLUSIONS

There are no distinguishing performance characteristics with regard to thromboembolic and hemorrhagic events between the CM and the SJM mechanical prostheses in MVR and MR. There was an identified need for improvement in the early and late anticoagulant management. A randomized trial with optimization of anticoagulant management between the CM and SJM mechanical prostheses is recommended.

Beneficial effect of both tranexamic acid and aprotinin on blood loss reduction in reoperative valve replacement surgery

BACKGROUND

Blood loss after cardiac surgery is a continuing concern of caregivers and patients. The acute inflammatory reaction initiated by the extracorporeal circuitry, necessary to perform the procedure, stimulates the coagulation cascade, and the resultant hyperfibrinolysis is considered to be a major contributing factor of blood loss. The necessity to reduce transfused blood products after cardiac surgery is important, as it reduces the potential transmission of serious viral infections, improves operative outcomes, and provides containment of costs. The purpose of this study was to compare the effect of synthetic antifibrinolytic tranexamic acid with naturally occurring antifibrinolytic aprotinin on blood loss and to study requirements for transfusion of blood products after repeat cardiac valve surgery.

METHODS AND RESULTS

Two randomized trials had been previously conducted, each comparing the respective treatment groups, aprotonin (AP group) and transexamic acid (TA group), with a control group [placebo (P)] in double-blind fashion with the same inclusion and exclusion criteria. The number of patients in the four designated groups are as follows: TA, 22; TA-P, 19; AP, 24; and AP-P, 36. The dosage of aprotinin (high-dose) encompassed a 280-mg loading dose infused after induction of anesthesia, 280 mg in the CPB prime solution, and 70 mg/h for a period of 6 hours. The tranexamic acid dose was 10 mg infused in 500 mL of normal saline. The blood loss was measured intraoperatively and postoperatively. The transfusion of homologous blood products was conducted in a standardized fashion. Both the TA and AP groups lost less blood intraoperatively, in total, less than either of the placebo groups, and less blood postoperatively than the TA-P group (P<.05). The postoperative blood loss (median) was 538 mL for the TA group, 455 mL for the AP group, and for the respective placebo groups, 1170 mL and 595 mL. The total blood loss was 1340 mL for the TA group, 1383 mL for the AP group, and 3250 mL and 2450 mL, respectively for the placebo groups. The total blood product use revealed no differences between the two placebo groups (P=NS) nor between the two treatment groups (P=NS).

CONCLUSIONS

Tranexamic acid and aprotinin are both effective in reducing intraoperative and postoperative blood loss and the need for blood product transfusion for patients undergoing reoperative cardiac valvular surgery.

Tranexamic acid reduces blood loss and transfusion in reoperative cardiac surgery

PURPOSE

The objective of this study was to assess the effect of tranexamic acid (TA), a synthetic antifibrinolytic, on blood loss and the need for transfusion of blood products following repeat cardiac valve surgery.

METHODS

After ethics committee approval, 41 patients scheduled for reoperative valve replacement were enrolled in this randomized, double blind, placebo controlled study. Patients were randomized to receive TA (10 g in 500 ml NSaline) or placebo (NSaline) as an iv bolus over 30 min, after anaesthesia induction and prior to skin incision. Intraoperative blood loss was assessed by estimating blood volume on drapes, weighing surgical sponges, and measuring suction bottle returns. Postoperative blood loss was measured from mediastinal chest tube drainage following surgery. Blood products were transfused according to a standardized protocol.

RESULTS

Patient demographics were similar for age, sex, cardiopulmonary bypass pump time, cross clamp time, surgical time, preoperative haemoglobin, coagulation profile, and the number of valves replaced during surgery. Tranexamic acid administration reduced intraoperative blood loss [median (range)] from 1656 (575-6270) to 720 ml (355-5616) (P < 0.01) and postoperative blood loss from 1170 (180-4025) to 538 ml (135-1465) (Intent to Treat n = 41, P < 0.01). The total red blood cells transfused (median, range) was reduced from 1500 (0-9300) ml to 480 (0-2850) ml (P < 0.01) in the TA group. In hospital complications and mortality rates were not reduced in the TA group.

CONCLUSION

Tranexamic acid reduced blood loss and the need for blood product transfusion and appears to be an effective treatment for patients undergoing reoperative cardiac valvular surgery.

Experimental use of somatosensory evoked potential for intraoperative identification of spinal cord blood supply

The role of sensory evoked potentials (SEPs) to be used intraoperatively to reliably predict spinal cord ischemia, caused by interruption of intercostal and of lumbar and sacral arteries, was evaluated in a canine model. Two groups were assessed: (A) interruption of intercostal arteries (n = 6) and (B) interruption of all posterior branches (n = 6). SEPs were evaluated intraoperatively as control and interruption of posterior vessel groups, and at 18-22 h after surgery. Neurologic assessment was performed preoperatively and 18-22 h postoperatively by modified Tarlov criteria. Morphological assessments were also performed. The assessment of the groups demonstrated prolongation of latency and loss of amplitude of SEP, but individual changes of SEPs were poor predictors of paraplegia. Ultrastructural changes correlated with neurologic findings. SEPs were unreliable for intraoperative identification of vessels critical to spinal cord blood supply, possibly related to anatomically different blood supply of sensory and motor tracts.

Fracture embolization of a Duromedics mitral prosthesis

The Duromedics bileaflet pyrolitic carbon mechanical prosthesis was introduced by Hemex in 1982 and subsequently acquired by Baxter. This communication documents a case of sudden leaflet fracture of a Duromedics mitral valve 48 months after implantation, which was managed successfully by replacement with a St. Jude Medical mechanical prosthesis. The patient presented in acute distress with paroxysmal atrial tachycardia and pulmonary edema. Transesophageal echocardiography was used to diagnose the leaflet fracture. The fracture had occurred transversely, with the fragments embolizing bilaterally to the iliofemoral arteries. These were removed at a subsequent operation. Cases of such fractures of the Duromedics prosthesis have been reported, with cavitation damage being the postulated mechanism.

Control of oxygen cytotoxicity with allopurinol and superoxide dismutase: a canine model of global myocardial ischemia-reperfusion injury

The purpose of this study was to assess the effects of acute pharmacological interventions on the ischemia-reperfusion damage in a canine model of hypothermic global myocardial ischemia. Three experimental groups each consisting of seven animals were subjected to 2 h of global ischemia followed by 1 h of reperfusion. Group A (control) used Tyers' iso-osmolar potassium cardioplegia solution; group B received allopurinol (40 mg/kg), 95% intravenously (IV) systemically with 5% added to the final infusion of Tyers' solution. In group C, superoxide dismutase (6.5 mg/kg) was used, one third of the total dose in the final delivery of the Tyers' cardioplegia solution and two thirds IV during the initial 5 min of reperfusion. In all three groups, myocardial temperature was maintained between 15 and 19 degrees C. Methods of evaluation included hemodynamic and echocardiographic parameters of ventricular function. Assessment was performed at three time periods: pre-cardiopulmonary bypass (control), 60 min postreperfusion and immediately post-volume loading (at 2 h after cardiopulmonary bypass). No significant deterioration of myocardial function was observed in either of the experimental groups after the use of these preservation techniques. Comparison of regression slopes based on analysis of covariance for myocardial performance, systolic function, and diastolic compliance did not demonstrate any significant differences between the groups. Two hours of global ischemia was not sufficient to cause measurable damage to the myocardium on the basis of which the pharmacological intervention with allopurinol and superoxide dismutase could be evaluated. The controversy surrounding the use of allopurinol and superoxide dismutase is discussed with the findings of this experimental protocol and is brought up for scientific dialogue.

Spinal cord protection with distal perfusion for thoracic and thoracoabdominal aortic surgery

Spinal cord protection is of extreme importance to avoid the catastrophic complication of paraplegia related to surgery for thoracic and thoracoabdominal aortic disease.P-' Spinal cord injury from surgi- cally induced ischemia for aortic surgery has a variable risk of paraplegia. The incidence of spinal cord injury varies extensively-aneurysms of the proximal descending thoracic aorta and thoracoabdominal aorta 3% to 35%;to repair of traumatic rupture of the thoracic aorta performed with simple cross-clamping with- out distal perfusion, 25%;to repair of acute type B dissections of the thoracoabdominal aorta, as high as 35%.

Unilateral versus bilateral internal mammary revascularization. Survival and event-free performance

BACKGROUND

The influence of unilateral (UL) and bilateral (BL) mammary artery revascularization, within age groups < or = 60 years and > 60 years, on patient survival, ischemic-related events, and interventional management was studied in 1142 patients who had coronary artery bypass graft surgery between 1984 and 1992.

METHODS AND RESULTS

UL revascularization was performed in 765 (67%) and BL in 377 (33%) patients with supplemental vein grafts. The overall early and hospital mortality rate was 2.7%. For UL in the age group < or = 60 years, it was 1.1%; for BL < or = 60 years, 1.3% (P = NS); for UL > 60 years, 4.3%; and for BL > 60 years, 2.8% (P = NS). Twenty-five preoperative patient characteristics representing demographics, extent of disease, concomitant disease, ventricular dysfunction, previous surgery, and status did not differentiate the patient groups (P = NS). Patient survival at 5 years was not different: 94% for UL < or = 60 years, 95% for BL < or = 60 years, 91% for UL > 60 years, and 86% for BL > 60 years (P = NS). The freedom from ischemic-related events was not different at 5 years (P = NS). The freedom from recurrent angina was 78% for UL < or = 60 years, 88% for BL < or = 60 years, 82% for UL > 60 years, and 83% for BL > 60 years (P = NS). The myocardial infarction freedom was 98% for UL < or = 60 years, 96% for BL < or = 60 years, 99% for UL > 60 years, and 97% for BL > 60 years (P = NS). The freedom from sudden unexpected death and cardiac death did not differentiate the groups (P = NS). The freedom from angioplasty and reoperation did not differentiate the groups (P = NS). The freedom from all ischemic-related and interventional events was 76% for UL < or = 60 years, 84% for BL < or = 60 years, 81% for UL > 60 years, and 79% for BL > 60 years (P = NS). A trend exists for less angina pectoris in the bilateral population < or = 60 years, which reflects in the trend in the freedom from overall events.

CONCLUSIONS

UL and BL mammary artery revascularizations have the same early mortality regardless of age but do not reveal any advantage for BL revascularization at 5 to 7 years.

Influence of coronary artery bypass and age on clinical performance after aortic and mitral valve replacement with biological and mechanical prostheses

The influence of prosthetic type, age, and coronary artery bypass grafting (CABG) on valve-related complications by valve position was evaluated in a population of 2353 bioprosthesis patients (mean age, 66.5 years; range, 13 to 89 years) and in a population of 1112 mechanical prosthesis patients (mean age, 59.1 years; range, 13 to 91 years). The follow-up was complete to 96% and 98%, respectively, for the bioprosthesis and mechanical prosthesis groups. The patient groups were evaluated by actuarial assessment of survival and valve complications and composites. Preoperative factors were evaluated for determination of significant independent predictors by multivariate proportional-hazard regression analysis. CABG was an influential factor in the actuarial analysis. Survival was superior for aortic mechanical replacements without CABG and for mitral replacements, both biological and mechanical, without CABG (P < .05). The freedom from thromboembolism (TE) and antithromboembolic hemorrhage (ATH) was greater for biological prostheses with and without CABG for aortic replacements (P < .05) but not for mitral replacements (P = NS). The freedom from valve-related mortality was not influenced by CABG for either position (P = NS). The freedom from valve-related reoperation was greater for biological prostheses with CABG than without CABG for both aortic and mitral replacements (P < .05). The evaluation of covariates as independent predictors revealed CABG to be a nonpredictor for aortic valve replacement (AVR) (P = NS) but a predictor of survival and valve-related reoperation for mitral valve replacement (MVR) (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Carpentier-Edwards standard porcine bioprosthesis: clinical performance to seventeen years

BACKGROUND

The role of porcine bioprostheses in cardiac valve replacement has been under review for several years. The literature deals primarily with age as a determinant of durability, as well as the intermediate-term performance of various prostheses. The performance of the Carpentier-Edwards first-generation standard porcine bioprosthesis is presented over the long-term with further documentation on age determinants.

METHODS

The "Guidelines for Reporting Morbidity and Mortality After Cardiac Valvular Operations" were used for definitions of valve-related complications, categorization, and statistical methods. The valve-related complications were evaluated in a time-related manner by actuarial life-table techniques. The Lee-Desu statistic test was used for comparison of performance by valve positions and age groups. Hazard function rates were demonstrated for complications and composites.

RESULTS

Of the Carpentier-Edwards porcine bioprostheses implanted in 1,195 patients (1,214 operations, 1,315 valves) commencing in 1975 the early mortality was 7.6% (92). The early mortality without concomitant procedures was 6.1% and with 11.7%. The late mortality was 5.3% per patient-year; 4.6% patient-year without and 7.5% per patient-year with concomitant procedures. The valve-related causes of late mortality (131) were thromboembolism (41), antithromboembolic hemorrhage (14), prosthetic valve endocarditis (20), nonstructural dysfunction (12), and structural valve deterioration (44). The valve-related deaths (early, 7; late, 124) were 21.2% of the total 617 total deaths. Reoperation for valve-related complications was performed in 406 patients (4.1% per patient-year), of which 327 were for structural valve deterioration (3.3% per patient-year). Mortality for reoperation was 0.5% per patient-year (49 patients) or 12.1%. Of the 49 deaths, 33 were caused by structural valve deterioration. The linearized occurrence rate for thromboembolism was 1.6% per patient-year (major, 0.9% per patient-year, and minor, 0.7% per patient-year). The fatal thromboembolic rate was 0.4% per patient-year (41), undifferentiated by valve position. The freedom from thromboembolism was 76% at 17 years (p = not significant by valve position) (major, 87%; fatal, 93%). The freedom from prosthetic valve endocarditis was 92% at 17 years (p = not significant by valve position). The freedom from reoperation, at 15 years, was 38%: aortic (AVR), 55%; mitral (MVR), 20%; and multiple valve replacement (MR), 24% (p < 0.05 AVR > MVR, MR). The freedom from structural valve deterioration, at 15 years, was 41%; AVR, 58%; MVR, 21%; MR, 36% (p < 0.05 AVR > MVR, MR). The freedom from structural valve deterioration was greater for advancing age groups (p < 0.05); AVR > or = 70 years 96% at 12 years, and 65 to 69 years 94% at 12 years and 82% at 15 years; MVR > or = 70 years 85% at 12 years, and 65 to 69 years 54% at 12 years. The freedom from valve-related mortality was 73% at 17 years: AVR, 80%; ; MVR, 61%; and MR, 67% (p < 0.05 AVR > MVR, MR). The freedom valve-related residual morbidity was 94% (p = not significant by valve position).

CONCLUSIONS

The Carpentier-Edwards standard porcine bioprosthesis continues to provide satisfactory clinical performance to 17 years. Thromboembolism is a more serious problem than structural failure: 92 major thromboembolic events with 41 fatalities compared with 44 fatalities of which 33 occurred with reoperation. The prosthesis is especially recommended for patients more than 65 years of age for AVR and more than 70 years of age for MVR.

Acadesine: a new drug that may improve myocardial protection in coronary artery bypass grafting. Results of the first international multicenter study. Multinational Acadesine Study Group

The effect of acadesine, an adenosine-regulating agent, on the incidence of myocardial infarction, all adverse cardiovascular outcomes (myocardial infarction, cardiac death, left ventricular dysfunction, life-threatening arrhythmia, or cerebrovascular accident) and mortality was assessed in 821 patients undergoing coronary artery bypass grafting. Patients were prospectively stratified to a high-risk group (age > 70 years, unstable angina, previous coronary bypass, unsuccessful angioplasty, or ejection fraction < 30%) or a non-high-risk group. They were randomized in a double-blind manner to placebo (n = 418) or acadesine (n = 403) by intravenous infusion over 7 hours (0.1 mg/kg per minute) and in the cardioplegic solution (placebo or acadesine; 5 micrograms/ml). Acadesine did not significantly affect the incidence of myocardial infarction in the overall study population, but it significantly reduced the incidence of Q-wave myocardial infarction in high-risk patients (placebo, 19.7%; acadesine, 10.0%; p = 0.032). The incidences of all adverse cardiovascular outcomes (placebo, 19.4%; acadesine, 18.4%) and overall mortality (placebo, 3.4%; acadesine, 2.7%) were similar between the two treatment groups. However, acadesine reduced the incidence of cardiac related events that contributed to deaths occurring during the first 3 postoperative days so that the incidence of death in this period was lower (placebo, 1.9%; acadesine, 0.2%; p = 0.038). No adverse events were related to acadesine treatment. Although overall there were no statistically significant between-group differences for the primary study end points, a secondary analysis in a prospectively defined high-risk subgroup suggests that acadesine may be beneficial in some patients.

Pregnancy and bioprostheses: influence on structural valve deterioration

The long-term performance of bioprostheses was evaluated in women 35 years of age or less to determine the influence of pregnancy on structural valve deterioration. Between 1972 and 1992, 237 female patients received 255 biological prostheses. Of the total operations, 53 were performed in patients who experienced pregnancy (P) and 202 in patients who were never pregnant (nonpregnant [NP]). The mean age of the P group was 23.0 +/- 5.8 years (standard deviation) (12 to 34 years) and of the NP group it was 27.1 +/- 6.3 years (8 to 35 years) (p < 0.05). The mean follow-up for the NP group was 6.8 years and for the P group it was 7.9 years. The late mortality was 2.26%/patient-year overall, 2.71%/patient-year for the NP group and 0.89%/patient-year for the P group (p = not significant [NS]). The P group of 52 patients had 94 pregnancies: 70 deliveries (74.5%) and 24 abortions (25.5%) (therapeutic, 14 [15%]). There were a total of 143 valve-related complications (P, 35; NP, 108); the majority for structural valve deterioration (SVD) 43% (109 patients), P 51% (27 patients) and NP 41% (82 patients) (p = NS). The valve-related reoperation rate paralleled the SVD rate at 42% (107 patients), P 51% (27 patients) and NP 40% (80 patients) (p = NS). The overall reoperative mortality rate was 6.0%. The interval from initial implant to reoperation was 99.6 +/- 3.6 months (p = NS groups P and NP).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of porcine bioprostheses and mechanical prostheses in multiple valve replacement operations

The performance of porcine bioprostheses and mechanical prostheses in multiple valve replacement operations was evaluated in 494 patients with 553 operations between 1975 and 1992. Porcine bioprostheses were implanted in 351 multiple replacement operations and 202 operations were performed with mechanical prostheses. The mean age of the bioprosthesis group was 59.1 +/- 14.4 years and of the mechanical prostheses group, 55.9 +/- 13.3 years. Concomitant procedures, primarily coronary artery bypass grafting, were performed in 27.4% (96 patients) of the bioprosthesis group and 20.8% (42 patients) of the mechanical prosthesis group (p = not significant [NS]). The early mortality for the bioprosthesis group (BP) was 12.0% (42 patients), whereas for the mechanical prosthesis (MP) group it was 10.9% (22 patients) with no difference (p = NS) for the performance with or without concomitant procedures, primarily coronary artery bypass grafting. The total cumulative follow-up was 1,914 years for BP and 458 years for MP group. The late mortality was different between the groups (p < 0.05), 6.1%/patient-year for BP and 3.7%/patient-year for MP. The difference in late mortality was not different (p = NS) for performance of concomitant procedures and not different (p = NS) for the absence of concomitant procedures, 5.6%/patient-year for BP and 2.2%/patient-year for MP. The freedom from thromboembolism- and antithromboembolic-related hemorrhage favored the biological population (p < 0.05) at 10 years with 79.7% +/- 3.4% for BP and 75.4% +/- 5.0% for MP. The freedom from structural valve deterioration was 100% for MP, whereas for the BP group, 94.7% +/- 1.6% at 5 years and 65.9% +/- 4.3% at 10 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitroflow pericardial bioprosthesis: clinical performance to ten years

The Mitroflow pericardial bioprothesis, a second generation pericardial prosthesis, has clinical performance assessment to 10 years. This bioprosthesis was used in 445 operations in 445 patients between 1982 and 1992 inclusive (mean age, 59.1 years; age range, 19 to 94 years). There were 253 aortic valve replacements (AVR), 155 mitral valve replacements (MVR), 31 multiple valve replacements (MR), and 6 tricuspid valve replacements. Concomitant procedures were performed in 40 patients (14.2%). The age group distributions (years) were less than or equal to 35 years, 28 patients; 36 to 50 years, 79; 51 to 64 years, 167; 65 to 69 years, 70; and 70 years or more, 101 patients. The total follow-up was 1,524 patient-years (mean, 5.4 years), 96% complete. The early mortality was 6.3%/patient-year (28 patients) and the late mortality was 4.1%/patient-year (96 patients). Concomitant procedures did not influence either early or late mortality (p = not significant [NS]). The overall patient survival at 10 years was 58% +/- 5% (p = NS by valve position). The overall freedom from structural valve deterioration (SVD) at 8 years was 69% +/- 3% and at 10 years, 45% +/- 7%; and at 8 years AVR 80% +/- 4%, MVR 58% +/- 6%, and MR 38% +/- 11% (p < 0.05, AVR > MVR > MR). The freedom from thromboembolism (TE) was 87% +/- 2%, overall at 10 years, and was not different by valve position (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical performance of biological and mechanical prostheses

Prosthetic valve replacement remains the most viable alternative for the treatment of severely diseased heart valves. The cumulative experience of mechanical protheses and bioprostheses was evaluated for a 10-year performance comparison: Carpentier-Edwards standard porcine bioprosthesis (CE-S), 1,214 operations; Carpentier-Edwards supraannular porcine bioprosthesis (CE-SAV), 2,489; and mechanical prostheses, 1,364 operations (St. Jude Medical, Carbomedics, Duromedics, and Björk-Shiley Monostrut). The freedom from thromboembolism and hemorrhage at 10 years was 82% for CE-S, 78% for CE-SAV, and 65% for mechanical prostheses (p < 0.05). The relationship existed for major thromboembolism and hemorrhage, 91% (CE-S), 87% (CE-SAV), and 88% (mechanical) (p < 0.05), without clinical relevance. The freedom from structural valve deterioration and valve-related reoperation favored mechanical prostheses (p < 0.05) at 10 years (structural failure: 78% for CE-S, 81% for CE-SAV, and 99% for the mechanical group; reoperation: 74% for CE-S, 76% for CE-SAV, and 88% for mechanical prostheses). The freedom from fatal reoperation was not clinically different: 96% for CE-S, 99% for CE-SAV, and 99% for mechanical prostheses (p < 0.05) at 10 years. The freedom from valve-related mortality was not different (p = not significant) at 10 years: 87% for CE-S; 92% for CE-SAV; and 91% for mechanical. The freedom from permanent impairment or residual morbidity, primarily from thromboembolism, was 95% for CE-S, 92% for CE-SAV, and 95% for mechanical group (p < 0.05) but not clinically relevant.(ABSTRACT TRUNCATED AT 250 WORDS)

Carpentier-Edwards supraannular porcine bioprosthesis: clinical performance to twelve years

The Carpentier-Edwards supraannular porcine bioprosthesis, a second-generation biologic prosthesis, has had clinical performance assessment to 12 years. This bioprosthesis was used in 2,489 operations in 2,444 patients between 1982 and 1992, inclusive (mean age 64.1 years, age range 6 to 89 years). There were 1,335 aortic valve replacements (AVR), 938 mitral valve replacements (MVR), and 200 multiple valve replacements (MR). Concomitant procedures were performed in 1,017 cases (40.9%). The age group distribution was: 35 years or younger, 83 patients; 36 to 50 years, 245; 51 to 64 years, 728; 65 to 69 years, 458; and 70 years and older, 975. The total follow-up was 12,785 patient-years (mean, 5.1 years) and was 96% complete. The early mortality rate was 7.4% (185 patients), and the late mortality was 4.9%/patient year (623). Concomitant procedures influenced both early and late mortality (p < 0.05). The overall patient survival at 12 years was 44% +/- 3% (p < 0.05, AVR > MVR, MR). The freedom from thromboembolism was not different by valve position. The freedom from major thromboembolism at 12 years was 82% +/- 4% (p = not significant by valve position). The overall freedom from antithromboembolic hemorrhage was 96% +/- 1% at 12 years (p < 0.05, AVR > MVR > MR). The overall freedom from valve-related reoperation at 12 years was 58% +/- 5% (p < 0.05, AVR > MVR, MR), and from valve-related mortality 89% +/- 2% (p < 0.05, AVR > MVR > MR). The freedom from residual morbidity (permanent impairment) at 12 years was 87% +/- 4% (p = not significant by valve position).(ABSTRACT TRUNCATED AT 250 WORDS)

Structural deterioration in Carpentier-Edwards standard and supraannular porcine bioprostheses

The Carpentier-Edwards standard (CE-S) porcine bioprosthesis was implanted in 1214 operations (1975 to 1985) and the Carpentier-Edwards supraannular (CE-SAV) bioprosthesis was implanted in 2,489 operations (1982 to 1992 inclusive). The early mortality was 7.6% and 7.4% for the CE-S and CE-SAV groups, respectively; the late mortality was 5.3% per patient-year and 4.9% per patient-year, respectively. The cumulative follow-up was 9,968 patient-years for the CE-S group and 12,784 patient-years for the CE-SAV group. Concomitant procedures were performed in 26.8% of the patients who received a CE-S and in 40.9% of those who received a CE-SAV (p < 0.05). The mean age of the patients receiving a CE-S was 57.3 years (range, 8 to 85 years) and was 64.1 years (range, 6 to 89 years) in those receiving a CE-SAV. The CE-S group consisted of 578 atrial valve replacements (AVRs), 512 mitral valve replacements (MVRs), and 115 multiple valve replacements (MRs). The CE-SAV group consisted of 1,335 AVRs, 938 MVRs, and 200 MRs. There was a total of 165 cases of structural valve deterioration (SDV) in the CE-SAV group (AVR, 35; MVR, 98; and MR, 32). The effect of trimming the aortic wall was also considered: 20 of the 931 trimmed prostheses used for MVRs and MRs and none of the 207 reduced-trimmed prostheses exhibited SVD. The cumulative follow-up was 5,422 years for the patients with trimmed prostheses and 470 for those with reduced-trimmed prostheses.(ABSTRACT TRUNCATED AT 250 WORDS)

Reoperation in biological and mechanical valve populations: fate of the reoperative patient

From 1975 through 1992 inclusive, reoperative valve replacement (REOP) was required by 12.9% of patients (708/5,499). Of 1,355 patients with mechanical prostheses (MP), 46 (3.4%) came to REOP versus 662 of 4,144 patients (16%) with biological prostheses (BP). Early REOP mortality rate was 17.4% (8/46) for MP and 10.6% (70/662) for BP (p = not significant). It was higher with age greater than 75 years (p < 0.05) and trended higher with concomitant procedures and with increasing number of REOPs (p = not significant). The percentage freedom from REOP at 5 and 10 years for all BP was 96.0% +/- 0.4% and 74.9% +/- 1.1% compared with 93.6% +/- 1.2% and 87.9% +/- 2.5% for MP. The most common cause of REOP in the BP patients was structural valve deterioration, which was uncommon in patients with MP (72% versus 2% of REOP but only 15% versus 0.1% of initial implants). Nonstructural dysfunction was the leading cause of REOP in the MP group (65% versus 11%). Prosthetic valve endocarditis (18% versus 10%) and thromboembolic complications (10% versus 1%) were also more frequent causes of REOP in MP patients. However, the increased relative role of these factors with MP is due to the minimal incidence of structural valve deterioration. When related to the original choice of MP versus BP, only thromboembolic complication (3.8 times) was more prevalent as a cause of REOP in patients receiving MP at their previous procedure (p = not significant). For patients who previously received BP, structural valve deterioration (69 times) was more likely to lead to REOP than with MP (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Tricuspid valve replacement: porcine bioprostheses and mechanical prostheses

The clinical performance of tricuspid valve replacement with bioprostheses and mechanical prostheses was assessed in a series of 5,489 total valve replacement operations performed from 1975 to 1992. There were 97 (1.8%) tricuspid valve replacements in 94 patients (16 men, 78 women) with a mean age of 55.4 +/- 13.8 years. Bioprostheses (mean patient age, 55.9 +/- 14.1 years) were used in 83 operations and mechanical prostheses (mean patient age, 52.1 +/- 11.9 years) were used in 14 operations. There were 30 isolated tricuspid valve replacements and 67 tricuspid valve replacements incorporated in multiple valve replacements. The total cumulative follow-up was 360 patient-years (bioprostheses, 321 years; mechanical prostheses, 39 years) (96.8% complete). The mean follow-up was 3.7 years (bioprostheses, 3.9 years; mechanical prostheses, 2.8 years) (p = not significant). The early mortality was 14.4% (bioprostheses, 14.5%; mechanical prostheses, 14.3%) (p = not significant) (isolated replacement, 13.3%; multiple replacement, 14.9%). The late mortality was 9.2% per patient-year (isolated replacement, 12.2% per patient-year; multiple replacement, 7.9% per patient-year). The freedom from structural valve deterioration at 5 and 7 years was 100% for mechanical prostheses and 97.1% +/- 2.9% for bioprostheses (p = not significant). For isolated tricuspid valve replacement, the freedom from structural valve deterioration for bioprostheses was 90.9% +/- 8.7% at 5 years and at 7 years (p = not significant). For the mechanical prostheses, the freedom was 100%.(ABSTRACT TRUNCATED AT 250 WORDS)

Medtronic Intact porcine bioprosthesis: clinical performance to seven years

The clinical performance of the Medtronic Intact porcine bioprosthesis was evaluated in 1,084 patients (mean age 66.4 years, range 9 to 91 years) who had a total of 1,099 implantations between 1985 and 1992, inclusive. There were 709 aortic valve replacements, 297 mitral valve replacements, and 80 multiple valve replacements. Concomitant procedures were performed in 432 (39.3%). The age group distribution (years) was 35 or younger in 20 patients, 36 to 50 in 64, 51 to 64 in 274, 65 to 69 in 225, 70 or older in 500. The total follow-up time was 2,741 patient-years (mean, 2.5 years) and was 97.5% complete. The early mortality rate was 7.1% and late mortality was 3.9% per patient-year. The overall patient survival at 7 years was 70% +/- 3%. The freedom from major thromboembolism was 94% +/- 1% at 7 years (p = not significant for valve positions). The freedom from reoperation at 7 years was 93% +/- 1%; freedom from valve-related mortality was 89% +/- 2%. The freedom from structural valve deterioration at 7 years was 97% +/- 1% (aortic valve replacement 97% +/- 1%; mitral valve replacement 97% +/- 2%). The freedom from structural valve deterioration among age groups was not different for the overall population, aortic valve replacement, or mitral valve replacement. Hemodynamic assessment revealed obstructive properties for aortic valve replacement sizes of 21 and 23 mm and for mitral valve replacement sizes of 25 and 27 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Porcine bioprostheses in the elderly: clinical performance by age groups and valve positions

Porcine bioprostheses have been recommended and used for cardiac valve replacement in the elderly. A review of 1,984 patients with 2,042 operations, performed between 1975 and 1992, has afforded a detailed evaluation of clinical performance by valve positions and age groups within the elderly population. The numbers of operations performed by age groups were 65 to 69 years, 719; 70 to 74 years, 745; 75 to 79 years, 431; 80 to 84 years, 119; and 85 years or older, 28. The early mortality rate overall was 9.5% (195 patients), range 6.9% to 17.8% by age groups (p < 0.05), and 11.9% with concomitant procedures and 7.6% without (p < 0.05). The total cumulative follow-up was 10,060 patient-years (mean, 4.9 years). The late mortality rate was 7.0%/patient-year (for age groups, 5.8% to 13.4%/patient-year) (p = not significant). The patient survival at 15 years ranged from 25% +/- 4% for 65 to 69 years to 9% +/- 5% for 75 to 79 years (p < 0.05). The freedom from valve-related complications and composites at 10 years revealed differences (p < 0.05) by age groups only for structural valve deterioration: 85% +/- 2% for 65 to 69 years versus 98% +/- 2% for 80 to 84 years. The overall freedom from structural valve deterioration at 10 years for aortic valve replacement was 98% +/- 1%; for mitral valve replacement, 79% +/- 3%; and for multiple replacement, 86% +/- 7% (p < 0.05, aortic valve replacement > mitral valve replacement).(ABSTRACT TRUNCATED AT 250 WORDS)

The Medtronic Intact porcine bioprosthesis: clinical performance to eight years

The Medtronic Intact porcine bioprosthesis was implanted in 274 patients, in 278 operations, between 1984 and 1992 inclusive. Of the total patient population, 171 patients had 175 aortic valve replacements (AVR), 75 had mitral valve replacement (MVR), two had tricuspid valve replacement and 26 had multiple valve replacement (MR). Concomitant procedures, primarily coronary artery bypass, was performed in 97 (34.9%). The follow up was 98.2% complete; total follow up was 758 patient-years, mean 2.8 years. The early mortality was 6.5% (18 patients) and the late mortality 4.0% per patient-year (30 patients). Of the late deaths, 10 were valve-related-thromboembolism (n = 2), anticoagulant-related hemorrhage (n = 1), prosthetic valve endocarditis (n = 4), non-structural dysfunction (n = 2), and structural valve deterioration (n = 1). Only one death occurred as a consequence of reoperation. The freedom from thromboembolism at six and eight years was-overall 86 +/- 4%; major 96 +/- 1%; fatal 99 +/- 1%. The overall linearized rate of thromboembolism was 3.0% per patient-year. The freedom from anticoagulant-related hemorrhage was 93 +/- 3%; non-structural dysfunction 87 +/- 9%; and structural valve deterioration 97 +/- 2% (AVR 97 +/- 2% at six and eight years, MVR 100% at six years). The freedom from SVD by age groups was- < or = 35 years 100%; 36-50 years 94 +/- 6%; 51-65 years 98 +/- 2%; and > or = 65 years 97 +/- 2% (p = NS). The freedom from valve-related mortality at six and eight years was 86 +/- 8%; residual morbidity 96 +/- 1%; and reoperation 91 +/- 3%. The Medtronic Intact, zero-pressure glutaraldehyde fixed prosthesis requires continued long term assessment to determine if the low incidence of structural valve deterioration is maintained.

Actuarial versus actual risk of porcine structural valve deterioration

Actuarial analysis, using nonparametric (e.g., life table or Kaplan-Meier) or parametric (statistical modeling) methods, is used to describe and compare survival probabilities by allowing for partial survival times (censoring). Although devised to describe freedom from death, this method has been extended to nonfatal complications, such as freedom from tissue valve failure. However, the risk described for nonfatal events is that which a patient would experience provided he were immortal. And patients with valve disease have a relatively high risk of dying, generating the question: "What is the chance the valve will fail before the patient dies?" To answer this more practical (for individual patient management and population resource allocation) question requires an estimate of what we call actual failure, that is, the percentage of patients whose valve will actually fail before they die. This risk is less than the risk which the usual actuarial curve describes. This difference increases with patient age, because older patients have a lower risk of tissue failure and a higher risk of death than younger patients.

Additive effect of allopurinol and deferoxamine in the prevention of spinal cord injury caused by aortic crossclamping

Fourteen domestic swine were divided into two groups. Group A (n = 7) was the control group, in which no pharmacologic intervention was applied. In group B (n = 7), the ischemic-reperfused spinal cord was treated with the combination of allopurinol (50 mg/kg/day for 3 days before the day of operation) and deferoxamine (Desferal, 50 mg/kg administered intravenously over 3 to 4 hours). The administration of deferoxamine was completed 1 hour before crossclamping. The crossclamp was placed on the descending aorta just distal to the left subclavian artery for 30 minutes. Proximal hypertension was controlled with sodium nitroprusside and volume depletion. Methods of assessment included an evaluation of the neurologic status of the animals by quantitative Tarlov criteria, blood flow by radiolabeled microspheres, and histologic examination of the spinal cord. All animals in the control group, group A, were completely paraplegic with 0% recovery by Tarlov criteria at 24 hours after the removal of the crossclamp. In contrast, all animals in group B, in which the combination of allopurinol and deferoxamine was used, completely recovered (100% recovery by Tarlov criteria), and at 24 hours after the ischemic episode they were able to walk with no difficulty and had intact sensation. Functional parameters of these animals fully correlated with the morphologic findings. Widespread acute neuronal injury and vacuolation of neuropil were observed in the control group of animals. In contrast, animals in group B showed much less pronounced morphologic changes after the same period of ischemia. In summary, the combined use of these agents significantly (p < 0.001) reduced the incidence of paraplegia induced by aortic crossclamping with 82% additivity.

Cardiac valve replacement surgery: prostheses and technological considerations

Cardiac valve replacement surgery has advanced considerably over the past 20 years with suitable choices of mechanical prostheses and bioprostheses as valvular substitutes. The extensive developments over the past three decades have been introduced to reduce or eliminate valve related complications, namely thromboembolism, anticoagulant related hemorrhage, and structural failure as well as to optimize hemodynamic performance. The mechanical prostheses have been developed to eliminate structural failure, to facilitate prevention of blood status and thrombus formation, to facilitate intraoperative leaflet positioning and to facilitate radiopacity for evaluation of prosthesis function. The biological valvular prostheses, namely porcine aortic or bovine pericardium, have been developed with tissue preservation, together with stent designs, that contribute to preservation of anatomical characteristics and biomechanical properties of the leaflets. The implantation of the various present generation bioprostheses and mechanical prostheses requires special considerations to support ventricular performance and avoid technical complications.