Early follow-up of patients with the Medtronic Intact porcine valve

Fifty years of the pericardial valve: Long-term results in the aortic position

It is now 50 years since the development of the first pericardial valve in 1971. In this time significant progress has been made in refining valve design aimed at improving the longevity of the prostheses. This article reviews the current literature regarding the longevity of pericardial heart valves in the aortic position. Side by side comparisons of freedom from structural valve degeneration are made for the valves most commonly used in clinical practice today, including stented, stentless, and sutureless valves. Strategies to reduce structural valve degeneration are also discussed including methods of tissue fixation and anti-calcification, ways to minimise mechanical stress on the valve, and the role of patient prosthesis mismatch.

Improved Long-Term Survival for Rheumatic Mitral Valve Repair Compared to Replacement in the Young

Background:

Mitral valve (MV) repair offers potential advantages over replacement in patients with rheumatic heart disease (RHD). We present the first long-term study that compares MV repair with replacement in children with RHD.

Methods and Results:

Single institute retrospective review of patients with RHD under 20 years of age, who underwent their first isolated MV surgery between 1990 and 2006. Of the 81 patients, 98% were Māori or Pacific Islander. The median age was 12.7 (3-19) years. The MV was repaired in 59%, a mechanical valve replacement (MVR) took place in 35% and bioprosthetic valve replacement in 6% of the patients. Follow-up data were available for 91.4% of the patients with mean follow-up of 7.6 years (range 0-19.4 years), a total of 620 patient years. Actuarial survival at 10 and 14 years for patients with MVR was 79% and 44%, compared to 90% and 90% for patients who underwent repair ( P = .06). Actuarial freedom from late reoperation at 10 and 14 years for patients with MVR was 88% and 73%, compared to 76% and 76% for patients with repair ( P = .52). Actuarial freedom from thrombotic, embolic, and hemorrhagic events at 10 and 14 years for patients with MVR was 63% and 45%, compared to 100% and 100% for patients with repair P < .01).

Conclusion:

This study shows that MV repair is superior to replacement for RHD in the young with follow-up to 19 years. Repair offers a survival advantage, greater freedom from valve-related morbidity, and long-term durability that equals that of MVR.

Doppler haemodynamics and effective orifice areas of Edwards SAPIEN and CoreValve transcatheter aortic valves

AIMS

Transcatheter aortic valve implantation (TAVI) is a new therapy for severe aortic stenosis in high-risk patients. So far, no reference values for the echocardiographic assessment of this new class of heart valves have been established. The aim of our study was to determine Doppler haemodynamics and the effective orifice area (EOA).

METHODS AND RESULTS

We retrospectively analysed the earliest transthoracic echocardiographic examinations of 146 stable patients after successful TAVI (median 8±20 days). Doppler examinations were analysed for peak instantaneous velocity, peak, and the mean systolic gradient. EOA was determined using the continuity equation. Patients with severe paravalvular aortic or mitral valve regurgitation were excluded. The overall peak instantaneous velocity (n=146) was 2.0±0.4 m/s with a peak systolic gradient of 17.1±7.4 mmHg and a mean gradient of 9.3±4.5 mmHg. The mean EOA was 1.82±0.43 cm2 with an indexed EOA of 1.0±0.27 cm2/m2. In general, all prostheses showed similar values-with the exception of the Edwards Sapien 23 mm which was associated with higher velocities and peak pressure gradients.

CONCLUSION

Our study establishes the normal range for Doppler haemodynamics of four transcatheter aortic valve prostheses. Compared with previously published data of surgically implanted bioprostheses percutaneous valves tend to have similar EOA values but lower mean peak velocities and pressure gradients. In comparison with physiological haemodynamics; however, this new class of heart valves is still associated with a mild obstruction.

Diagnostic evaluation of left-sided prosthetic heart valve dysfunction

Prosthetic heart valve (PHV) dysfunction is a rare, but potentially life-threatening, complication. In clinical practice, PHV dysfunction poses a diagnostic dilemma. Echocardiography and fluoroscopy are the imaging techniques of choice and are routinely used in daily practice. However, these techniques sometimes fail to determine the specific cause of PHV dysfunction, which is crucial to the selection of the appropriate treatment strategy. Multidetector-row CT (MDCT) can be of additional value in diagnosing the specific cause of PHV dysfunction and provides valuable complimentary information for surgical planning in case of reoperation. Cardiac magnetic resonance imaging (CMR) has limited value in the evaluation of biological PHV dysfunction. In this Review, we discuss the use of established imaging modalities for the detection of left-sided mechanical and biological PHV dysfunction and discuss the complementary role of MDCT in this context.

Impact of Prosthesis-Patient Mismatch on Survival After Mitral Valve Replacement

Background— We recently reported that valve prosthesis-patient mismatch (PPM) is associated with persisting pulmonary hypertension after mitral valve replacement. Thus, the objective of this study was to evaluate the impact of PPM on mortality in patients undergoing mitral valve replacement.

Methods and Results— The indexed valve effective orifice area was estimated for each type and size of prosthesis being implanted in 929 consecutive patients and used to define PPM as not clinically significant if >1.2 cm 2 /m 2 , as moderate if >0.9 and ≤1.2 cm 2 /m 2 , and as severe if ≤0.9 cm 2 /m 2 . Moderate PPM was present in 69% of patients; severe PPM was seen in 9%. For patients with severe PPM, 6-year survival (74±5%) and 12-year survival (63±7%) were significantly less than for patients with moderate PPM (84±1% and 76±2%; P =0.027) or nonsignificant PPM (90±2% and 82±4%; P =0.002). On multivariate analysis, severe PPM was associated with higher mortality (hazard ratio, 3.2; 95% confidence interval, 1.5 to 6.8; P =0.003).

Conclusions— Severe PPM is an independent predictor of mortality after mitral valve replacement. As opposed to other independent risk factors, PPM may be avoided or its severity may be reduced with the use of a prospective strategy at the time of operation. For patients identified as being at risk for severe PPM, every effort should be made to implant a prosthesis with a larger effective orifice area.

The evolution of bioprosthetic heart valve design and its impact on durability

Bioprosthetic heart valves have evolved over the years into remarkably useful and predictable devices. During this process, a number of specific designs have come and gone, and a few have remained. Many design changes were successful, and many were not. This article will describe the successes and failures of the various bioprosthetic valve designs and will detail the specific reasons why a particular design change succeeded or failed to improve bioprosthetic valve performance.

The Medtronic Intact Bioprosthesis: Clinical and Hemodynamic Performance Over 13 Years

We evaluated our results over 13 years with the aortic-position Medtronic Intact bioprosthesis. Our study involved 91 consecutive patients with isolated aortic valve replacement with the Medtronic Intact bioprosthesis. The follow-up was complete for 95%. Mean follow-up was 6.61 years (range 16 days-13 years), 590 patient years. Early mortality rate was 3.3%. Late mortality was 23 patients. Survival at 13 years was 53.52% (SD = 7.63%). The linearized rate of major thromboembolism was 0.34% per patient year; rate of major bleeding events was 0.33% per patient year. The rate of nonstructural dysfunction was 0.16% per patient year. Rate of reoperation was 0.53% and rate of structural valve deterioration was 0.16% per patient year. New York Heart Association (NYHA) postoperative classes were I to II in 92.21%. Gradients were as follows: 21 to 23.87 mm Hg, 23 to 18 mm Hg, 25 to 15.5 mm Hg, and 27 to 16.50 mm Hg. Structural valve deterioration was low during the 13 years of follow-up. Valve gradients and areas remained the same over the follow-up period. The Medtronic Intact bioprosthesis shows excellent clinical and hemodynamic performance at 13 years of follow up.

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.

Early experience with the mosaic bioprosthesis: a new generation porcine valve

BACKGROUND

The Mosaic bioprosthesis is a new generation stented porcine valve.

METHODS

Between May 1995 and April 1998, this valve was implanted in the aortic position in 98 patients (70 men; mean age, 69.2 years [34.2 to 83.6 years]). Preoperatively 35 patients were in New York Heart Association functional class 3 or 4. Fifty-nine patients underwent concomitant procedures. The mean duration at follow-up in January 1999 was 23.7 +/- 10.2 months (0.3 to 39.4 months) and totaled 193 patient-years. All but one survivor was in New York Heart Association class 1 or 2.

RESULTS

Early complications included 1 death, 3 reoperations for bleeding, greater than mild regurgitation (paravalvar) in 1 patient and thromboembolism in 4 patients. Late complications included four deaths, study-valve endocarditis in 3 patients, more than mild regurgitation or hemolysis in 2, and thromboembolism in 2 patients. Late follow-up echocardiography in all survivors showed a mean transaortic gradient of 13.6 +/- 6.7 mm Hg, and an aortic valve area of 1.80 +/- 0.61 cm2. Valve replacement was followed by a significant and sustained decrease in left ventricular mass for all valve sizes. There has been no primary structural valve failure.

CONCLUSIONS

The early experience with the Mosaic valve in the aortic position has been promising.

The mosaic bioprosthesis in the aortic position: hemodynamic performance after 2 years

BACKGROUND

The Mosaic bioprosthesis is a porcine valve combining several new features to improve hemodynamics and durability: a low profile stent for reduced flow obstruction, zero pressure fixation to maintain the natural collagen crimp, and the amino oleic acid antimineralization treatment to enhance durability.

METHODS

Fifty-five Mosaic valves were implanted in the aortic position since February 1994. Data from these patients (group 1) were compared with data from 52 patients who had received a Hancock Modified Orifice II aortic valve (group 2). The mean patient age was 72.0 (+/-5.9) years for group 1 and 76.8 (+/-4.7) years for group 2. Clinical examinations including transthoracic echocardiography were performed 6 and 24 months postoperatively.

RESULTS

Mild aortic insufficiencies were found in 2 patients in group 1 and in 3 patients in group 2. There were no embolic or bleeding complications. One Mosaic patient required reoperation due to mitral insufficiency. During the reoperation, a small (approximately 3 mm) thrombus was noted on the outflow side of a Mosaic cusp. The valve was removed and replaced prophylactically. In the 2-year follow-up, hemodynamic measurements showed mean pressure gradients of 12.4 mm Hg for the 21 mm, 11.3 mm Hg for the 23 mm, and 15.4 mm Hg for the 25 mm prostheses in the Hancock group. In the Mosaic group, mean pressure gradients were 14.8 mm Hg for the 21 mm, 10.9 mm Hg for the 23 mm, and 11.5 mm Hg for the 25 mm valves. Differences between pressure gradients and effective orifice areas of the Hancock and the Mosaic valves were not statistically significant. Early mortality in group 1 was 3.6% and in group 2 3.8%. Overall mortality was 12.7% and 13.5%, respectively.

CONCLUSIONS

The Mosaic valve has low pressure gradients for all sewing ring diameters. Compared with the Hancock Modified Orifice valve, there was no statistically significant gradient difference but a tendency toward better hemodynamics was noted in the Mosaic group after 2 years.

The medtronic intact porcine valve: ten-year clinical review

OBJECTIVE

Our objective was to assess the long-term mortality and morbidity associated with the Medtronic Intact valve (Medtronic, Inc, Minneapolis, Minn).

METHOD

Between 1983 and 1996, 447 patients (280 men and 167 women) received 466 Intact valves: 280 aortic, 156 mitral, and 30 tricuspid. The mean age was 57 years (median 63 years), with 45% younger than 60 years. The mean New York Heart Association class was 3.1. The follow-up was 98% complete and extended for 39 months (1-154 months) and 1324 patient-years. There were 32 valves at risk at 10 years after implantation. Doppler echocardiography was performed whenever possible in patients followed up for longer than 4 years (mean 8 years) after implantation.

RESULTS

Ten-year overall actuarial survival was 30% +/- 6% (14% +/- 7% for New York Heart Association classes IV-V and 39% +/- 8% for classes I-III). At 10 years freedom from infective endocarditis was 92% +/- 3%, freedom from thromboembolism was 80% +/- 5%, and freedom from nonstructural valve deterioration was 95% +/- 2%. Ten-year freedom from explantation was 64% +/- 6%, freedom from valve-related events was 51% +/- 6%, and freedom from valve-related death was 88% +/- 3%. There were 26 examples of structural valve deterioration, mainly caused by leaflet calcification (in 17 cases) and by buttress detachment (in 6 cases). In the aortic position at 10 years freedom from structural valve deterioration was 81% +/- 9%, but with only 1 event in patients older than 40 years (freedom 92% +/- 8%) and 100% freedom in patients older than 60 years. There was also 100% freedom from structural valve deterioration in the tricuspid position. In the mitral position freedom was 65% +/- 8%, with no significant difference between age groups.

CONCLUSION

The Intact valve provides superior results in the aortic position in patients older than 40 years and in the tricuspid position at all ages.

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.

Hydrodynamic function of second generation porcine bioprosthetic heart valves

The hydrodynamic function and leaflet dynamics of second generation porcine valves prepared with low- or zero-pressure fixation have been studied and compared to first generation porcine bioprostheses, bileaflet, and tilting disc mechanical valves. The Carpentier-Edwards Supra-Annular and Hancock II valves showed lower pressure drops than the Medtronic Intact valve and first generation porcine valves, and comparable overall energy losses to mechanical valves at normal cardiac outputs. Only the zero-pressure fixed Intact valve showed synchronous leaflet opening. Delayed leaflet opening and high opening pressures were found in both low- and high-pressure fixed porcine valves. All porcine bioprostheses showed high open leaflet bending strains. Fixation of valve leaflets with "near zero" pressure fixation and a more physiological neutral geometry is necessary to ensure synchronous leaflet opening at low flows and a reduction in commissural bending strains.

The Carpentier-Edwards supra-annular porcine bioprosthesis: clinical performance to 8 years of a new generation porcine bioprosthesis

The Carpentier-Edwards supra-annular porcine bioprosthesis has been utilized at the University of British Columbia since its introduction in 1982. The prosthesis was designed to improve hemodynamics with the supra-annular configuration and to reduce tissue failure with low-pressure glutaraldehyde preservation of the porcine aortic tissue. The prosthesis was inserted in 1,956 patients with 2,129 prostheses between 1982 and 1989. The mean age of the patient population was 62.7 years (range 13 to 87 years). The mean follow-up was 3.7 years per patient. The freedom from thromboembolism and antithromboembolic therapy-related hemorrhage at 8 years was 92% for aortic valve replacement (AVR), 83% for mitral valve replacement (MVR), and 92% for multiple valve replacement (MR) (p less than 0.05, AVR greater than MR greater than MVR). The freedom from structural valve deterioration was 86% for AVR, 73% for MVR, and 96% for MR at 8 years (p less than 0.05, AVR greater than MR greater than MVR). The freedom from nonstructural valve dysfunction and prosthetic valve endocarditis was not different between positions (p = NS). The freedom from valve-related mortality at 8 years was 98% for AVR, 94% for MVR, and 98% for MR (p less than 0.05, AVR greater than MR greater than MVR). The freedom from residual morbidity was not different at 8 years (p = NS). The freedom from treatment failure (valve-related mortality and residual morbidity) was 96% for AVR, 89% for MVR, and 94% for MR (p less than 0.05, AVR greater than MVR greater than MR).(ABSTRACT TRUNCATED AT 250 WORDS)

The zero pressure fixed medtronic intact porcine valve: clinical results over a 6-year period, including serial echocardiographic assessment

Between 1983 and 1990, 219 patients had 224 Medtronic Intact porcine valves inserted. There were 94 aortic, 110 mitral, and 20 tricuspid valve replacements. The mean patient age was 52 years. Mean follow-up was 33.3 months and was 97.7% complete. There was only one example of structural valve degeneration occurring at 25 months, giving an actuarial freedom of 99% at 6 years. Reoperation was performed in seven patients. At 6 years, actuarial survival was 71%, freedom from infective endocarditis 96%, freedom from thromboembolism 91%, freedom from reoperation 93%, and freedom from valve-related complications 86%. Doppler echocardiography was performed in 48 of the 70 patients operated upon between August 1983 and October 1986 and who remained alive at the current review. Their follow-up averaged 4.7 (3-6.7) years. The results were compared to a similar examination performed in 1987 by the same operator. No patient had significant regurgitation. Valve gradients and areas remained the same in the two studies in the mitral position (3.8 +/- 1.33 mmHg) and the mean aortic gradient had reduced from 17 +/- 5.2 mmHg in 1987 to 13 +/- 2.8 mmHg in the current study (p = 0.02). These medium-term results are considered encouraging.

Long-term results of Ionescu-Shiley valve in the tricuspid position

A retrospective analysis of the long-term results of using the Ionescu-Shiley pericardial bioprosthesis in the tricuspid position was carried out on 73 patients (8 men, 65 women). Of these procedures, ten were tricuspid valve replacement alone and the remainder were in combination with other valve procedures. The mean follow-up was 9.6 years (range, 4 to 18 years). The mean age of the patients was 53 years (range, 27 to 78 years). Seventy-one of the patients suffered tricuspid valve dysfunction from rheumatic heart disease. There were 13 postoperative deaths (within 30 days), giving a mortality rate of 17.8%. The actuarial survival at 10 years was 71% +/- 4.2%. Of the survivors, 49 (79.6%) were in functional class I or II. Primary tissue valve failure in the tricuspid position occurred in 1 patient 12 years after implantation and required reoperation. In another patient bioprosthetic tricuspid valve endocarditis developed. There was no incidence of thromboembolic complications. We conclude that the Ionescu-Shiley pericardial bioprosthesis was a satisfactory prosthesis in the tricuspid position in patients with acquired valvar dysfunction.