Hemodynamic evaluation of the CarboMedics prosthetic heart valve in the aortic position: comparison of noninvasive and invasive techniques

Influence of valve size, orientation and downstream geometry of an aortic BMHV on leaflet motion and clinically used valve performance parameters

The aim of this study was to reconcile some of our own previous work and the work of others to generate a physiologically realistic numerical simulation environment that allows to virtually assess the performance of BMHVs. The model incorporates: (i) a left ventricular deformable model to generate a physiological inflow to the aortic valve; (ii) a patient-specific aortic geometry (root, arch and descending aorta); (iii) physiological pressure and flow boundary conditions. We particularly studied the influence of downstream geometry, valve size and orientation on leaflet kinematics and functional indices used in clinical routine. Compared to the straight tube geometry, the patient-specific aorta leads to a significant asynchronous movement of the valve, especially during the closing of the valve. The anterior leaflet starts to close first, impacts the casing at the closed position and remains in this position. At the same time, the posterior leaflet impacts the pivoting mechanisms at the fully open position. At the end of systole, this leaflet subsequently accelerates to the closed position, impacting the casing with an angular velocity of approximately -477 rad/s. The valve size greatly influences the transvalvular pressure gradient (TPG), but does not change the overall leaflet kinematics. This is in contrast to changes in valve orientation, where changing valve orientation induces large differences in leaflet kinematics, but the TPG remains approximately the same.

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.

Prosthesis-Patient Mismatch After Aortic Valve Replacement: Impact of Age and Body Size on Late Survival

BACKGROUND

The purpose of this study was to identify patient subgroups in which prosthesis-patient mismatch most influenced late survival.

METHODS

Over a 12-year period, 1,400 consecutive patients underwent bioprosthetic (933 patients) or mechanical (467) aortic valve replacement. Prosthesis-patient mismatch was defined as prosthetic effective orifice area/body surface area less than 0.75 cm2/m2 and was present with 11% mechanical and 51% bioprosthetic valves.

RESULTS

With bioprosthetic valves, prosthesis-patient mismatch was associated with impaired survival for patients less than 60 years old (10-year: 68% +/- 7% mismatch versus 75% +/- 7% no mismatch, p < 0.02) but not older patients (p = 0.47). Similarly, with mechanical valves, prosthesis-patient mismatch was associated with impaired survival for patients less than 60 years old (10-year: 62% +/- 11% versus 79% +/- 4%, p < 0.005) but not older patients (p = 0.26). For small patients (body surface area less than 1.7 m2), prosthesis-patient mismatch did not impact survival with bioprosthetic (p = 0.32) or mechanical (p = 0.71) valves. For average-size patients (body surface area 1.7 to 2.1 m2), prosthesis-patient mismatch was associated with impaired survival with both bioprosthetic (p < 0.05) and mechanical (p < 0.005) valves. For large patients (body surface area greater than 2.1 m2), prosthesis-patient mismatch was associated with impaired survival with mechanical (p < 0.04) but not bioprosthetic (p = 0.40) valves.

CONCLUSIONS

Prosthesis-patient mismatch had a negative impact on survival for young patients, but its impact on older patients was minimal. In addition, although prosthesis-patient mismatch was not important in small patients, prosthesis-patient mismatch negatively impacted survival for average-size patients and for large patients with mechanical valves.

Rest and Exercise Performance of the Medtronic Advantage Bileaflet Valve in the Aortic Position

BACKGROUND

The aim of the study was to evaluate rest and exercise performance and left ventricular mass regression of the Medtronic Advantage (Medtronic, Inc, Minneapolis, MN) prosthesis in the aortic position at 1 year at a single center as part of a multicenter, prospective clinical trial.

METHODS

Between May 2002 and June 2003, 63 consecutive patients underwent aortic valve replacement with a Medtronic Advantage prosthesis (84.1% male; mean age, 56.0 +/- 9.7 years; ejection fraction, 56.5 +/- 15.8%). Valve lesions were stenosis (n = 20), mixed (n = 34), and insufficiency (n = 9). Concomitant procedures were performed in 34.9%. Follow-up was 100% complete. Echocardiographic data were obtained early postoperatively and at 1 year, combined with stress echocardiography by treadmill. Mean pressure gradients, stroke volume, and left ventricular mass were determined by echocardiography. Data are presented as mean +/- standard deviation.

RESULTS

Operative mortality was 0%. Valve-related complications were observed in 2 patients (endocarditis, n = 1; thromboembolic event, n = 1). There was no case of antithromboembolic hemorrhage, prosthesis-related explant, or reoperation. One patient showed moderate paravalvular regurgitation. Mean pressure gradients 1 year postoperatively ranged from 6.3 to 11.0 mm Hg across all valve sizes. Left ventricular mass regression at 1 year was 18.4% across all valve sizes (p < 0.001). No severe patient-prosthesis mismatch (effective orifice area index < or = 0.65 cm2/m2) could be observed.

CONCLUSIONS

After 1 year, the Medtronic Advantage valve shows comparable transvalvular mean pressure gradients across the valve sizes used during rest and exercise. This is accompanied by a significant left ventricular mass regression, an important indicator for long-term survival.

Patient‐Prosthesis Mismatch After Small‐Size Stentless Aortic Valve Replacement

OBJECTIVE

The aim of this study was to determine the occurrence of patient-prosthesis mismatch (P-PM) after aortic valve replacement (AVR) with a small-size Cryolife O'Brien (CLOB) bioprosthesis and to evaluate its clinical and hemodynamic implications.

METHODS

Sixty-two patients (mean age 70.9 +/- 5.2 years, 77.8% females), receiving a labeled 21-23 mm CLOB between 1993 and 2000, were retrospectively studied. Effective orifice area (EOA) was calculated by the continuity equation and then indexed to the patient's body surface area (BSA) to obtain the indexed EOA (EOAI). Based on previous observations a mismatch was defined as EOAI <or= 0.85 cm2/m2.

RESULTS

Twelve patients (20%) at discharge, two (3.3%) at 6 months and none at late controls had an EOAI <or= 0.85 cm2/m2. At ANOVA determinants of mismatch were female sex (p < 0.001), age (p = 0.01), and patient's annulus index (PAI, p < 0.001). Patients with mismatch had higher mean gradients (MG, p = 0.01, and p < 0.001 at discharge and 6 months, respectively) and EOAI correlated with MG at discharge (r2= 0.72, p < 0.001) and 6-month (r2= 0.40, p = 0.001) studies. At 1 year no difference in MG was detected between patients with or without mismatch (p = ns) and EOAI did not correlate with MG (r2= 0.01, p = ns). Midwall fractional shortening did not differ in patients with or without mismatch (p = ns). Patients with an EOAI >or= 0.8 cm/m2 showed an earlier concentric remodeling up to 1 year; no difference was demonstrated at later studies between groups. Survival and clinical status results were not affected by an EOAI <or= 0.85 cm2/m2.

CONCLUSIONS

After AVR with CLOB mismatch occurred early postoperatively in a small number of patients without clinical repercussions. EOAI, significantly increasing over time, was adequate to BSA in all patients at late controls.

Numerical Simulation of a Systemic Flow Test Rig

In this study, numerical simulation was carried out to investigate the dynamic response of a systemic flow test rig that is widely used for in vitro study of prosthesis in the cardiovascular system. In the system the physiological impedance of systemic circulation was modeled as a resistance-capacitance-resistance type. The system analysis was directly based on differential equations describing the system dynamics, and numerically solved using the fourth-order Runge-Kutta method. Results showed that pressure in the systemic circulation test rig could be successfully simulated with the developed model. From the numerical experiment, it was found that the maximum stroke of the driving mechanism, the flow coefficients and opening of the control valves, and the initial volume of air in the compliance strongly affect the dynamic performance of the test rig. The numerical method developed is a useful tool in the design and optimization of the system configuration.

Hemodynamic evaluation of normally functioning Sulzer Carbomedics prosthetic valves

The Sulzer Carbomedics prosthetic heart valve (CP) is a commonly used mechanical valve in clinical practice. In the present study, we used conventional and color Doppler echocardiography to assess the hemodynamics of normally functioning CP in the aortic (n = 73) and mitral (n = 127) positions. Our findings demonstrate no significant correlation of Doppler-measured peak and mean pressure gradients and effective orifice area with implanted valve size and actual orifice areas, measured directly by the manufacturer for CPs in both the mitral and aortic positions. However, it is still useful to measure effective orifice area by Doppler because a value in the normal or nonstenotic range points to an unobstructed prosthesis in the aortic or mitral position, in the absence of poor left ventricular ejection fraction. A value in the stenotic range could mean a normally functioning or obstructed prosthesis and, therefore, may need further investigation, such as assessment of valve leaflet motion by transthoracic or transesophageal echocardiography or fluoroscopy. Valve regurgitation as evaluated by color Doppler flow mapping was mild in practically all CPs in the aortic position, and in the majority of CPs in the mitral position.

Hemodynamic evaluation of 19-mm Carpentier-Edwards pericardial bioprosthesis in aortic position

BACKGROUND

The aortic Carpentier-Edwards pericardial bioprosthesis offers good long-term clinical outcomes with a low rate of structural deterioration. However, little in vivo hemodynamic data is available for this bioprosthesis.

METHODS

To determine the hemodynamic performance of the 19-mm Carpentier-Edwards pericardial valve, both cardiac catheterization and dobutamine stress echocardiography were electively performed in 10 patients. The mean age at the study was 71.6 +/- 4.4 years and the mean body surface area was 1.39 +/- 0.11 m2. The peak-to-peak gradient, instantaneous peak gradient, mean gradient, and valve orifice area were measured by standard cardiac catheterization. The Doppler-derived gradients and valve orifice area were also measured both at rest and during dobutamine infusion.

RESULTS

The average peak-to-peak gradient, instantaneous peak gradient, mean gradient, and valve orifice area measured by catheterization were 13.0 +/- 5.4 mmHg, 28.5 +/- 7.7 mmHg, 12.0 +/- 4.9 mmHg, and 1.55 +/- 0.45 cm2, respectively. The peak and mean Doppler gradients, and valve orifice area by resting echocardiography were 27.7 +/- 9.5 mmHg, 12.3 +/- 4.8 mmHg, and 1.39 +/- 0.26 cm2, respectively. At a dosage of 10 microg/kg/min of dobutamine, the mean Doppler gradient rose mildly to 22.2 +/- 4.8 mmHg, while the cardiac output increased from 4.49 +/- 0.44 to 6.64 +/- 0.87 L/min. The valve orifice area during the 10 microg/kg/min dobutamine infusion (1.55 +/- 0.25 cm2) was significantly larger than its value at rest (p < 0.05).

CONCLUSIONS

With acceptable hemodynamic performance, use of the aortic 19-mm Carpentier-Edwards pericardial valve is a reliable option for elderly patients with a small annulus.

Hemodynamic and clinical impact of prosthesis-patient mismatch in the aortic valve position and its prevention

Prosthesis-patient mismatch is present when the effective orifice area of the inserted prosthetic valve is less than that of a normal human valve. This is a frequent problem in patients undergoing aortic valve replacement, and its main hemodynamic consequence is the generation of high transvalvular gradients through normally functioning prosthetic valves. The purposes of this report are to present an update on the concept of aortic prosthesis-patient mismatch and to review the present knowledge with regard to its impact on hemodynamic status, functional capacity, morbidity and mortality. Also, we propose a simple approach for the prevention and clinical management of this phenomenon because it can be largely avoided if certain simple factors are taken into consideration before the operation.

Stentless bioprostheses have ideal haemodynamics, even in the small aortic root

OBJECTIVE

To determine normal Doppler and 2D gradients and flow characteristics of the Freestyle stentless aortic bioprosthesis related to valve size.

BACKGROUND

The Freestyle stentless aortic bioprosthesis is one of the newer aortic xenografts. Only limited data are available of the echocardiographic flow characteristics during a mid-term follow-up period of this valve. Therefore valve performance related to valve size was measured during a follow-up period of two years.

METHODS

175 consecutive patients with a Freestyle aortic bioprosthesis underwent an echocardiographic and Doppler examination according to a common protocol. Investigations were done within 4 weeks after operation, after 3 to 6 months, and after 1 and 2 years.

RESULTS

With a valve size from 19 to 27 mm mean gradients decreased from 8.0 +/- 5.1 mmHg at discharge to 5.8 +/- 3.8 mmHg after 3-6 months (p < 0.001). Thereafter gradients remained stable. The performance index, the ratio of the measured effective orifice area in the patient divided by the effective orifice area measured in vitro increased from 69 +/- 20% at discharge to 79 +/- 29% after one, two and three years. Performance index was especially very high in the smaller sized valves with a performance index of 85 +/- 17% for the 21 mm valve. During follow-up mean gradients remained below 10 mmHg even in the 21 mm valve.

CONCLUSION

Stentless xenografts have ideal haemodynamics, even in the small aortic root.

Haemodynamic performance of aortic pericardial bioprostheses and bileaflet prostheses at rest and during exercise: implications for the surgical management of patients with small aortic roots

OBJECTIVE

To determine the haemodynamic behaviour, at rest and during exercise, of aortic valve pericardial bioprostheses and different sizes of bileaflet prosthesis.

DESIGN

Observational study.

SETTING

Tertiary medical centre.

PATIENTS AND INTERVENTIONS

74 patients (33 women, 41 men; mean age 64 years) in whom 40 pericardial bioprostheses and 34 bileaflet prostheses sized 19, 21, or 23 mm had been implanted to replace aortic valves.

MAIN OUTCOME MEASURES

Doppler echocardiography at rest and at peak exercise, between 12 and 47 months after surgery.

RESULTS

All patients achieved a significant increase in heart rate, systolic blood pressure, and cardiac output with exercise. Transvalvar pressure fall, valve area, and left ventricular systolic and diastolic function indices also underwent significant changes with exercise. Reductions in peak and mean transvalvar pressure, at rest and at peak exercise, were greater in patients with small valves (p < 0.05). Valve areas and effective area index were greater in the patients with larger valves (p < 0.001). There were no significant differences between patients with mechanical and biological prostheses with regard to transvalvar pressure fall and valve areas at rest and at peak exercise.

CONCLUSIONS

19 mm and 21 mm aortic prostheses and bioprostheses continue to create significant obstruction, particularly with exercise.

The CarboMedics "Top-Hat" supraannular prosthesis

BACKGROUND

The CarboMedics "Top-Hat" supraannular prosthesis was designed to permit the implantation of a larger prosthesis.

METHODS

Between June 1993 and November 1996, 127 patients (average age, 61.8+/-10.2 years) received a CarboMedics "Top-Hat" supraannular aortic prosthesis. The average follow-up was 15.7 months, and all surviving patients underwent echocardiographic study. This group is compared with 656 patients in whom a standard CarboMedics prosthesis was implanted and also with 2,927 patients who received other aortic prostheses.

RESULTS

Using the standard and the supraannular sizers, there was an average increase of one size in favor of the supraannular prosthesis: 18.9+/-2.8 mm standard versus 20.8+/-2.6 mm supraannular (p < 0.005). For each prosthesis size (19 to 23 mm), the body surface area of the patients in whom a CarboMedics supraannular prosthesis was implanted was significantly smaller than that in those who received a CarboMedics standard prosthesis or any other model. Hospital mortality was 3.9%, and late mortality was 5.5%. The actuarial survival was 86.5%+/-3.9% at 42 months.

CONCLUSIONS

Using the CarboMedics supraannular prosthesis allows implantation of a larger prosthesis compared with the standard CarboMedics prosthesis or other models. This advantage is especially important in patients with a small aortic root.

Simultaneous Doppler and catheter transvalvular pressure gradients across St Jude bileaflet mitral valve prosthesis: in vivo study in a chronic animal model with pediatric valve sizes

A mixture of valve types has been used in previous in vivo studies to assess the accuracy of Doppler echocardiography compared with catheter-measured pressure gradients across prosthetic mitral valves. However, limited data exist regarding the most commonly used bileaflet mechanical valve. We studied 14 sheep with St Jude Medical mechanical mitral valves. Continuous wave Doppler data were obtained across each of the 3 valve orifices. Hemodynamic data were obtained simultaneously by direct measurements with catheters. Valve sizes commonly used in the pediatric population in the mitral position (23 mm, 25 mm, and 27 mm) were studied. Linear regression analyses of Doppler-predicted versus catheter-measured gradients provided correlation coefficients ranging from 0.75 to 0.91. Agreement analysis demonstrated a scatter of Doppler data about the regression line. Although a reasonably good correlation of Doppler-predicted peak and mean pressure gradients across bileaflet mechanical valves exists in the mitral position, caution is needed when this method is applied to patients. Doppler overestimation was greatest across the 23-mm valves. Analyses of the specific orifice interrogated demonstrated higher estimated pressure gradients across the central orifice compared with the side orifices.

[Hemodynamic evaluations of patients with small aortic annulus with St. Jude Medical prosthetic heart valve]

As the elderly population in Japan increases, senile degenerative aortic valvular disease also tends to increase. These patients often have a small aortic annulus. The problem of "valve-patient-mismatch" occurs when a small prosthesis is inserted into a patient with a small aortic annulus. To avoid annular enlargement after aortic valve replacement (AVR), we tried to use a small-sized St. Jude Medical (SJM) valve. From September 1988 through November 1996, 110 AVR were performed in our institution. In these cases, 30 underwent AVR with a small sized SJM valve (male < or = 21 mm, female < or = 19 mm). Dobutamine stress echocardiography was performed in 19 patients who had undergone AVR with a small-sized SJM valve. Surgical results were also compared between patients with small aortic annulus and those with normal-sized aortic annulus. Using Doppler echocardiography, pressure gradients (PG), cardiac index (CI), effective orifice area (EOA), and performance index (PI) were calculated at rest and during stress. The mean body surface area (BSA) of patient who had undergone AVR with SJM19A, 19HP and 21A was 1.40, 1.42 and 1.56 m2, respectively. With dobutamine stress, heart rates, PG and CI increased significantly. Mean and maximum PG of patients with 19HP (8.0 and 15.4 mmHg at rest, 12.9 and 28.0 mmHg under stress, respectively) and 21A (9.5 and 19.1 mmHg at rest, 16.5 and 35.3 mmHg under stress, respectively) were relatively low. EOA index (EOAI) of patient with 19HP showed the highest values mean 0.93 cm2/m2. PIs tended to be higher with HP models than with standard models. The tests were completed without significant side effects such as frequent ventricular arrhythmias. Among the cases with small aortic annulus, there were no operative deaths or hospital deaths. There were also no late deaths, episodes of hemorrhage or thrombosis. Conclusions. In our institution, AVR was performed safely without any aortic annular enlargement with a small aortic anulus in small BSA patients. Postoperative hemodynamic data obtained by echocardiography were satisfactory for all patients at rest and even during maximum dobutamine stress test.

Functional evaluation of the bileaflet mechanical valve in the aortic position using dobutamine-stress echocardiography: is a 23-mm prosthetic valve adequately large enough?

The issue of valve prosthesis-patient mismatch in small annular patients is still controversial. The hemodynamic function of bileaflet mechanical valves in the aortic position was examined using dobutamine-stress echocardiography. Forty-four patients were enrolled in the study and divided into 5 groups, according to prosthesis size, from 21 mm to 29 mm. The aortic peak pressure gradient (APG) increased significantly in all groups with dobutamine-stress and exceeded 50 mmHg in 83% of the 21-mm group, in 64% of the 23-mm group, and in 33% of the 25-mm group. The APG even exceeded 80 mmHg in 22% and 18% of the 21-mm and 23-mm groups, respectively. In these cases, the potential of 'valve prosthesis-patient mismatch' was considered. From the relationship between the APG and the prosthesis valve area index (VAI), 'critical VAIs' were found where patients were likely to enter the 'mismatch' status; that is, 1.22 and 1.77 cm2/m2, respectively, for the 5 and 10 microg/kg per min stages of dobutamine stress. This critical VAI range is useful in predicting the 'mismatch' patients preoperatively. Alternative procedures or prostheses should then be selected for them.

Outcome analysis of 245 CarboMedics and St. Jude valves implanted at the same institution

BACKGROUND

Thromboembolism and valve-related death are major complications associated with prosthetic valve implants, but it is difficult to evaluate the relative incidence of these complications based on studies in which the implantation of only one valve is reported from any given institution. We therefore report the outcome of patients implanted at our institution during the same time period with either the recently released CarboMedics (CM) or the St. Jude Medical (SJ) valve prostheses.

METHODS

Between October 1994 and January 1996, 245 consecutive patients received either SJ (116 patients) or CM (129 patients) valves at our institution. Follow up of these patients was 99.6% complete, for a total of 318.5 cumulative patient-years (median follow-up, 1.4 years).

RESULTS

The 30-day mortality rates for SJ and CM implants were 3.4% and 3.1%, respectively. Actuarial survival and freedom from valve related mortality rates at 1.5 years for SJ and CM valves were 94%+/-2% versus 86%+/-3% (p = 0.03) and 100% versus 94%+/-2% (p = 0.005), respectively. There was no structural valve failure for either implant, but there were five thrombosed valves in the CM group and none in the SJ group (p = 0.04). All thrombosed valves were mitral (four mitral valve replacement, one aortic and mitral valve replacement). Two of the thrombosed valves were successfully explanted, whereas the three remaining patients died. Freedom from a thromboembolic event in the mitral position at 1.5 years, including thrombosed valves was 97%+/-3% and 83%+/-5% for SJ and CM valves, respectively (p = 0.04).

CONCLUSIONS

The results of this study suggest that further evaluation of thromboembolic outcomes after CM compared with SJ valve implantation is warranted.

Hemodynamic Comparison by Doppler Echocardiography of Valves in the Aortic Position: Value of the Continuity Equation to Assess Prosthetic Dysfunction

In 281 patients, we used Doppler echocardiography to compare the hemodynamic performance of different aortic prosthetic valves at three postoperative stages and investigated the value of the continuity equation in diagnosing aortic prosthetic obstruction. A baseline study was performed in 163 patients, a 5 +/- 2-month follow-up study was performed in 103 patients, and a 15 +/- 5-month follow-up study was performed in 65 patients. From baseline to the second study, left ventricular diastolic diameter, heart rate, and maximum (MG) and mean Doppler-derived gradient (MeG) decreased significantly, and left ventricular shortening fraction, systolic blood pressure, stroke volume, and prosthetic valvular area (PVA) increased significantly. No changes were found between the second and third studies. Thus, noninvasive hemodynamic values at the time of follow-up are reported in 171 patients: 86 with Björk-Shiley Monostrut, 27 with Carbomedics, 11 with Medtronic-Hall, 18 with Hancock modified, and 29 with Toronto valve bioprosthesis. Patients implanted with the Toronto had a larger prosthetic size (Monostrut 23 +/- 2 mm, Carbomedics 23 +/- 3 mm, Medtronic-Hall 23 +/- 2 mm, Hancock 23 +/- 2 mm, Toronto 25 +/- 2 mm, P < 0.01) despite a similar body surface area. MeG and MG were lower (MeG [in mmHg] Monostrut 12 +/- 5, Carbomedics 14 +/- 6, Medtronic-Hall 19 +/- 6, Hancock 11 +/- 4, Toronto 7 +/- 5; P < 0.01 between Toronto and all others), and PVA was greater (Monostrut 2.0 +/- 0.7 cm(2), Carbomedics 1.8 +/- 0.8 cm(2), Medtronic-Hall 1.6 +/- 0.7 cm(2), Hancock 1.7 +/- 0.5 cm(2), Toronto 2.2 +/- 0.9 cm(2); P < 0.01 between Toronto and Carbomedics, Medtronic-Hall, and Hancock), even compared with the same sizes in the other valves. A PVA of 0.9 cm(2) or less and MeG of 28 mmHg or more identified prosthetic obstruction with 100% sensitivity and 99% specificity. Hemodynamics change significantly from the early to the late postoperative state. The Toronto valve stentless porcine bioprostheses performs hemodynamically better than other valves. PVA measurement using the continuity equation may accurately identify prosthetic obstruction.

The CarboMedics valve: experience with 1,049 implants

BACKGROUND

The lack of valve rotatability, the structural deterioration, and the rate of valve-related complications with the standard mechanical bileaflet prosthesis led to the development of a new second-generation bileaflet valve in 1986.

METHODS

Between January 1989 and March 1994, 1,049 CarboMedics valves were implanted in 859 patients. The rotatability was used in 109 mitral prostheses (21.5%) and in 61 aortic prostheses (11.6%). Follow-up was 97.1% complete, with 3,049 patient-years.

RESULTS

The hospital mortality was 6.9% for the mitral group, 3.4% for the aortic group, and 10.7% for the double-valve group (p < 0.005). The actuarial survival curve at 5 years was 77.3% +/- 3.6%, 90.1% +/- 2.5%, and 79.2% +/- 3.7% (p = 0.0003), freedom from thromboembolism was 89.1% +/- 3.6%, 87.1% +/- 3.8%, and 68.8% +/- 8.2%, freedom from reoperation was 95.9% +/- 1.4%, 98.9% +/- 0.6%, and 94.9% +/- 2.4%, and freedom from valve-related complications was 68.8% +/- 4.1%, 79.5% +/- 3.5%, and 55.3% +/- 5.9% after mitral, aortic, and mitral and aortic valve replacement, respectively. There were five episodes of valve thrombosis, but no structural deterioration occurred.

CONCLUSIONS

The clinical performance of the CarboMedics valve is quite satisfactory, with a low incidence of valve-related mortality and morbidity. The rotatability feature was useful when the native valve was preserved or for repeat valve replacement.

Effects of dobutamine on aortic valve indexes in asymptomatic patients with bileaflet mechanical prostheses in the aortic valve position

We investigated the effects of alternating transvalvular flow rate on Doppler-derived aortic valve resistance and valve area in asymptomatic patients with mechanical aortic valve replacement under dobutamine infusion. The Gorlin-derived aortic valve area and continuity equation-derived aortic valve area seem to be less flow dependent; valve resistance tends to be flow dependent.

Extent and pattern of regression of left ventricular hypertrophy in patients with small size CarboMedics aortic valves

OBJECTIVE

To assess the extent and pattern of regression of left ventricular hypertrophy after valve replacement for aortic stenosis, we studied 26 patients receiving either 19 or 21 mm CarboMedics valves (group I, 13 patients) or either 23 or 25 mm CarboMedics valves (group II, 13 patients). The studies were done before the operation and after 3 years, and results were compared with those of 10 control patients.

METHODS

Left ventricular end-diastolic and end-systolic diameters and volumes, ejection fraction and fractional shortening, and interventricular septum and posterior wall thickness were measured. The ratio between interventricular septum and posterior wall thickness, the ratio between left ventricular wall thickness and left ventricular chamber radius, and the left ventricular mass were then calculated.

RESULTS

At follow-up there was a significant reduction in the left ventricular mass, interventricular septum, and posterior wall thickness for both patient groups (p < 0.01). However, only the posterior wall thickness reached normal values; the interventricular septum and the left ventricular mass indices were still significantly greater than in the control group (p < 0.01). Because of the incomplete regression of interventricular septal hypertrophy, the ratio between interventricular septum and posterior wall thickness was similar between both patient groups but it was significantly higher than in control subjects (p < 0.01). The ratio between wall thickness and chamber radius did not decrease significantly in group II patients, in whom it remained above the control values.

CONCLUSION

Having a bileaflet aortic prosthesis of one size larger did not seem to significantly influence the pattern and the extent of regression of left ventricular hypertrophy after an intermediate period of follow-up.

Hemodynamic evaluation of the Carbomedics R, St Jude Medical HP and Sorin-Bicarbon valve in patients with small aortic annulus

A Doppler echocardiographic study was performed to evaluate the hemodynamic performance of three 19 mm size currently used bileaflet valve prosthesis (St Jude Medical Hydrodinamic Plus, Sorin-Bicarbon and Carbomedic Reduced) implanted in aortic position.

METHODS

Patients, 30, with the same profile receiving 19 mm size valve (ten for each valve type) were selected when body surface area (BSA) was > 1.7 m2. Doppler echocardiography was carried out at rest and after exercise, 60 days after surgery. Peak (Pg) and mean (Mg) gradients across the valve were recorded: the effective orifice area (EOA), and performance index (PI) were calculated.

RESULTS

No significant differences were observed between St Jude Medical and Sorin Bicarbon as far as peak and mean gradient, effective orifice area and performance index at rest and after exercise. A significant difference (P < 0.05) was demonstrated in the above mentioned parameters when Carbomedics-R valve were tested. This type of valve showed a lower EOA and PI with higher Pg and Mg gradient both at rest and after exercise.

CONCLUSION

The St Jude Hydrodymanic plus (Hp) and Sorin Bicarbon valves had similar performance and a better hemodynamic trend when compared to the Carbomedics-R valve in patients with large body surface areas. The Carbomedics-R valve shows a ineffective use of the total area of the prosthesis both at rest and after exercise.

Echocardiographic Appearance of Normally Functioning Sorin Bicarbon Valve Prostheses

A clinical and echocardiographic study was carried out to evaluate the performance of the Sorin Bicarbon bileaflet valve. From December 1990 to December 1994, 100 patients underwent isolated mitral (64) or aortic (36) valve replacement. There were 39 males and 61 females, with ages ranging from 21 to 73 years (mean 62 ± 9.6 years). Forty-three patients underwent a transthoracic continuous pulsed color Doppler echocardiogram at 3 and 6 months postoperatively. For mitral prostheses, the parameters calculated were valve area, pressure half-time and mean gradient; for aortic prostheses, peak and mean gradients were measured. Results were compared by analysis of variance to those obtained in patients matched for sex, body surface area, cardiac rhythm, site, and size of the prosthesis who had St. Jude Medical or CarboMedics valves implanted. No statistically significant differences were found among the 3 prosthetic heart valves. The operative mortality was 7%; 3 cases of fatal cerebral hemorrhage occurred in the early postoperative period. There was 1 late mortality, 1 case of transient cerebral ischemia, and 1 of gastric bleeding, all occurring inpatients with mitral prostheses. Midterm follow-up was satisfactory, although a larger series is required to confirm these results.

Six-Year Experience with CarboMedics Prosthetic Heart Valves

Between July 1989 and July 1995, 89 CarboMedics prosthetic heart valves were implanted in 70 patients (38 males, 32 females) ranging in age from 13 to 54 years (mean 33 years). Forty-one of these patients underwent mitral valve replacement, 10 had aortic valve replacement, and 19 had double aortic and mitral valve replacement. Early mortality was 4.9%, 0%, and 15.8% respectively in these groups. Mean follow-up time was 3.4 years and was 95.4% complete (3 lost). There were 5 late deaths (7.7%); 1 in the mitral group, 1 in the aortic group, and 3 who had double valve replacements. Three of these late deaths were considered valve-related. The 5-year actuarial survival rates, hospital mortality excluded, were 97% for mitral, 88% for aortic, and 88% for double valve replacement. Preoperatively, 80% of the patients were in New York Heart Association functional class III or IV, whereas postoperatively, 99.5% of the patients were in class I or II. No structural failures were observed. There was 1 case of systemic embolism and 1 case of valve thrombosis, neither of these patients were taking anticoagulants. Hemorrhage was the most frequent complication; 1 of 4 events was fatal. A less intensive warfarin regimen and improvement in hepatic function may reduce hemorrhagic risk while maintaining thromboembolic protection. On the basis of this experience, the CarboMedics prosthetic heart valve appears to be an excellent mechanical prosthesis for cardiac valve replacement, in terms of hemodynamic performance and low thrombogenicity, in patients receiving anticoagulants.

Doppler Hemodynamics of CarboMedics Prosthetic Valves in Aortic Position at Rest and Exercise

To evaluate the size adequacy of CarboMedics prosthetic heart valves, Doppler pressure gradients after aortic valve replacement were determined at rest and immediately after exercise in 83 patients, at a mean time of 18.8 days after aortic valve replacement with CarboMedics prosthetic heart valves (31 standard and 52 R-series). There were 54 males and 29 females, average age 55 years; 12 had pure aortic stenosis, 47 had aortic regurgitation, and 24 had combined lesions. Exercise significantly increased (p < 0.01) the peak velocity (from 2.50 to 2.88 m/sec), the peak pressure gradient (from 25.9 to 34.6 mm Hg), and the mean pressure gradient (from 13.9 to 18.4 mm Hg). Significant differences were observed even in patients with seemingly large valve sizes. Significant correlation (p < 0.0001) was observed between pressure gradients at rest and immediately after exercise, as well as between pressure gradients and theoretical performance index. A theoretical performance index larger than 1.0 cm2/m2 was needed to obtain a postexercise Doppler peak pressure gradient of less than 60 mm Hg early after aortic valve replacement using either the Carbomedics standard or R-series prosthetic heart valves.

Influence of the size of aortic valve prostheses on hemodynamics and change in left ventricular mass: implications for the surgical management of aortic stenosis

Discussion of aortic valve replacement has primarily concerned the choice between tissue and mechanical prostheses. Less emphasis has been placed on prosthesis size. Despite technical advances increasing prosthesis orifice area, small valves implanted in the unenlarged aortic root may not be significantly less obstructive than the stenotic native valves they replace.

METHODS

In this work we studied 52 patients (31 women, 21 men; mean age 59.2 years) in whom valve prostheses sized 19, 21, 23, or 25 mm (30 bioprostheses and 22 tilting disc valves) had been implanted to replace stenotic aortic valves. Most patients with 19 or 21 mm prostheses were women. Doppler and conventional echocardiographic studies were performed in the 10 days preceding the operation and between 10 and 40 months (mean 18 months) after the operation. The patients receiving larger valve sizes had significantly larger body surface areas than those receiving smaller valve sizes (mainly women).

RESULTS

No significant differences were observed between preoperative and postoperative diameters or left ventricular systolic function parameters, but left ventricular mass and mass index decreased in all four groups (albeit nonsignificantly in the 19 mm group, and with less statistical significance in the 21 mm group than in the 23 and 25 mm groups). Postoperative peak and mean transvalvular pressure drops were significantly greater in the 19 mm group than in the other groups, and the 21 mm group had significantly greater transvalvular pressure drops than the 25 mm group. Postoperative effective valve area was significantly smaller in the 19 mm group than in the 21 mm group, and significantly smaller in the 21 mm group than in the 23 and 25 mm groups.

CONCLUSION

We conclude that despite undeniable recent improvements in the design of artificial heart valves, 19 mm aortic prostheses continue to create significant obstruction of the left ventricular outflow tract and, possibly as a consequence of this, fail to bring about significant reduction in left ventricular hypertrophy.

Clinical experience with the CarboMedics valve: early results with a new bileaflet mechanical prosthesis

Between January 1989 and August 1992, 612 CarboMedics mechanical prostheses (CarboMedics, Inc., Austin, Tex.) (295 mitral, 308 aortic, and 9 tricuspid) were implanted in 504 patients: 189 patients had isolated mitral valve replacement, 209 had isolated aortic valve replacement, and 106 had multiple valve replacement. The total follow-up was 1182 patient-years. The hospital mortality rate was 7.4% for mitral valve replacement, 5.3% for aortic valve replacement, and 13.2% for multiple valve replacement. Linearized rates for the different complications for mitral valve replacement, aortic valve replacement, and multiple valve replacement (in events per 100 patient-years) were, respectively, as follows: late mortality, 2.6 +/- 0.8, 1.5 +/- 0.5, and 3.9 +/- 1.3; thromboembolism [correction of thromboembolim], 3.7 +/- 0.9, 3.1 +/- 0.8, and 3.9 +/- 1.3; valve thrombosis, 0.5 +/- 0.3 for mitral valve replacement and 0.4 +/- 0.4 for multiple valve replacement; anticoagulant-related hemorrhage, 2.8 +/- 0.8, 1.9 +/- 0.6, and 2.6 +/- 1.1; nonstructural dysfunction, 1.6 +/- 0.6, 0.8 +/- 0.4, and 3.5 +/- 1.2; and reoperation, 1.1 +/- 0.5, 0.4 +/- 0.3, and 3.1 +/- 1.1. Actuarial estimates of freedom from the different complications for mitral valve replacement, aortic valve replacement, and multiple valve replacement (at 5 years of follow-up for mitral valve replacement and aortic valve replacement and 4.5 years for multiple valve replacement) were, respectively, as follows: overall death, 83% +/- 4%, 89% +/- 2%, and 76% +/- 4%; thromboembolism or valve thrombosis, 88% +/- 3%, 91% +/- 2%, and 86% +/- 5%; anticoagulant-related hemorrhage, 89% +/- 3%, 95% +/- 2%, and 90% +/- 5%; nonstructural dysfunction, 97% +/- 1%, 98% +/- 1%, and 91% +/- 3%; and reoperation, 96% +/- 2%, 99% +/- 1%, and 87% +/- 5%. There were no instances of prosthetic structural dysfunction. The performance of the CarboMedics valve is satisfactory at 5 years of follow-up but thromboembolic and hemorrhagic phenomena are still serious complications of mechanical prostheses.

Doppler echocardiographic assessment of normally functioning Starr-Edwards, carbomedics and Carpentier-Edwards valves in aortic position

Doppler echocardiography was performed in 168 normally functioning aortic prostheses to determine acceptable pressure gradients across the commonly used valves and to establish the relationship between valve size and gradients. There were 82 Carbomedics (C), 63 Starr-Edwards (SE), and 23 Carpentier-Edwards (CE) valves. Peak and mean gradients across the prostheses were measured by use of the simplified Bernoulli equation. CarboMedics valve had a lower peak and mean gradient than Starr-Edwards and Carpentier-Edwards valve (P < 0.05 when compared with Starr-Edwards). The authors observed a weak inverse correlation between valve size and peak and mean gradients in CarboMedics and Carpentier-Edwards valves but not in the Starr-Edwards valve. For the CarboMedics valve the peak pressure gradient (PPG) was 26.1 +/- 8.2 mm Hg and the mean pressure gradient (MPG) was 14.7 +/- 5.1 mm Hg; in Starr-Edwards valve the PPG was 32.8 +/- 9.1 mm Hg and the MPG was 19.5 +/- 5.6 mm Hg; in the Carpentier-Edwards valve the PPG was 28.7 +/- 10.1 mm Hg and the MPG was 16.1 +/- 5.2 mm Hg when size was not specified. The CarboMedics valves were noted to have a better hemodynamic profile in comparison with Starr-Edwards and Carpentier-Edwards prostheses.

Early in vivo experience with the Hemodynamic Plus St. Jude Medical heart valves in patients with narrowed aortic annulus

BACKGROUND

Small aortic orifice primarily resulted in heart prosthesis mismatch in a significant number of patients. The Hemodynamic Plus (HP) series of St. Jude Medical heart valves represents an interesting innovation, allowing a larger valve orifice area with an equivalent tissue annulus diameter.

METHODS

Hemodynamic characteristics of the 21-mm HP St. Jude Medical valve were prospectively compared with those of the standard 21-mm and 23-mm St. Jude Medical valves in three groups of 22 patients. Patients were selected from a database to be rigorously matched for age, sex, body surface area, functional class, underlying lesion, native valve opening area, left ventricular function, and preoperative peak and mean valve gradients. Postoperative evaluation (follow-up ranging from 3 to 24 months; mean, 11.5 months) included clinical examination and echocardiographic studies.

RESULTS

There was no operative mortality or significant perioperative complications. Short-term clinical follow-up was marked by a complete absence of valve-related complications. Presently, all but 1 patient in the 21-mm HP group and 2 in the 21-mm standard group are in New York Heart Association functional class I. Doppler echocardiography-derived mean and maximal pressure gradients were significantly lower in the 21-mm HP group (8.1 +/- 1.9 and 16.4 +/- 3.4 mm Hg) than in the 21-mm standard group (13.4 +/- 3.9 and 21.2 +/- 4.3 mm Hg; p = 0.002 and p = 0.0004, respectively), confirming the better hemodynamic performance already described in in vitro studies. Pressure gradients did not differ significantly between the 21-mm HP and the 23-mm standard groups. The 21-mm HP valve demonstrated the highest performance index; 0.66 +/- 0.08, compared with 0.49 +/- 0.09 for the 21-mm standard valve (p < 0.001) and 0.59 +/- 0.07 for the 23-mm standard valve (p < 0.001).

CONCLUSIONS

In vivo hemodynamic performance of the 21-mm HP valve corresponds closely to that of the 23-mm standard valve and is substantially better than that of the 21-mm standard valve. The 21-mm HP St. Jude Medical valve demonstrates excellent hemodynamic characteristics and can be recommended in normal-sized adult patients with narrow aortic root. This valve will minimize the need for aortic annulus enlargement.

Comparison of hemodynamic performances of St. Jude Medical and CarboMedics 21 mm aortic prostheses by means of dobutamine stress echocardiography

Dobutamine stress Doppler echocardiography was used to compare the hemodynamic performance of two small aortic bileaflet prostheses. Nineteen patients (14 female, mean age 64 years) who had undergone aortic valve replacement with 21 mm bileaflet valve prostheses (St. Jude Medical valve, n = 9, or CarboMedics valve, n = 10) were studied. Dobutamine infusion was started at a rate of 5 micrograms.kg-1.min-1 and increased to 10 and 20 micrograms.kg-1.min-1 at 15-minute intervals. Under maximum stress, heart rate and cardiac output increased by 70% and 120%, respectively, and mean arterial blood pressure decreased by 9%. Pulsed-wave and continuous-wave Doppler studies were performed at rest and at the end of each stage. Velocity ratio, effective orifice area, performance index, and discharge coefficient of the valve were calculated, and peak and mean velocities and pressure drops across the prostheses were measured. Dobutamine infusion produced similar increases in cardiac output in all patients. Effective orifice areas, discharge coefficients, and performance indexes were comparable for the two valve groups both at rest and maximum stress. Transvalvular velocities and pressure drops were also similar in the two valve groups. Transvalvular pressure drops were also comparable in patients with large body surface area. Dobutamine stress echocardiography is useful in the evaluation of the hemodynamic performance of prosthetic heart valves. St. Jude Medical and CarboMedics 21 mm prostheses have equally favorable hemodynamic performances in most patients under conditions of high cardiac output.

Hemodynamic assessment of carbomedics bileaflet heart valves by ultrasound: studies in the aortic and mitral positions

The bileaflet mechanical heart valve has become a popular prosthesis for implantation in both the aortic and mitral positions and a recent design by Carbomedics has received widespread use. Noninvasive assessment of these valves by Doppler ultrasound is important in characterizing their normal performance and in assessing the course of dysfunction. This study addressed the hypothesis that Doppler predicted pressure drops will correlate with catheter pressure drops within a valve size and position. A subhypothesis is that the pressure drops agree, and we expect this subhypothesis to fail due to pressure recovery effects. In a well-controlled in vitro model it was shown that the combined effects of pressure recovery and neglecting proximal velocities resulted in overestimation of catheter pressure drops for Carbomedics bileaflet valves. Inclusion of the proximal velocity reduced overestimation of peak pressure drops for aortic and mitral valves to clinically acceptable levels, and removed overestimation of mean pressure drops. Without correction for proximal velocity, overestimation of mitral pressure drops was reduced to 3.32% when means were calculated, but mean aortic pressure drops still overestimated the catheter standard significantly. It is concluded that proximal velocities should be included in Bernoulli analysis of Carbomedics heart valves. If the proximal velocity is not available, mitral valves may be best assessed using mean pressure drops, while aortic valve Doppler data, peak or mean, should be interpreted with caution.

Evaluation of the hemodynamic performance of small CarboMedics aortic prostheses using dobutamine-stress Doppler echocardiography

BACKGROUND

The well-known correlation between prosthetic valve orifice area and transvalvular gradients has raised concerns about the presence of significant residual gradients when the size of the prosthesis that can be implanted is limited by the presence of a small aortic annulus.

METHODS

Dobutamine-stress Doppler echocardiography was used to evaluate the hemodynamic performance of small CarboMedics aortic prostheses (19 mm and 21 mm) in 18 patients (16 women; mean age, 64 years) who had undergone aortic valve replacement 23.5 +/- 19 months (standard deviation) previously. Dobutamine infusion was started at a rate of 5 micrograms.kg-1.min-2 and increased to 10 and 20 micrograms.kg-1.min-2 at 15-minute intervals. Pulsed and continuous wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area, performance index, and discharge coefficient of both valves were calculated, and peak and mean velocity and pressure drop across the prostheses were measured.

RESULTS

Heart rate and cardiac output increased by 74% and 94%, respectively, and mean arterial blood pressure decreased by 9% at maximum stress. Effective orifice area, discharge coefficient, and performance index were comparable in both valve sizes at rest and maximum stress. Also, there was no significant difference in mean transvalvular pressure drop (gradient) for 19-mm and 21-mm prostheses at rest (8.1 +/- 8.4 and 4.8 +/- 3.8 mm Hg) or maximum stress (15.1 +/- 14.2 and 8.8 +/- 5.8 mm Hg, respectively). No significant correlation could be demonstrated between transvalvular pressure drop and patient's body surface area.

CONCLUSIONS

These data show that 19-mm and 21-mm CarboMedics aortic prostheses exhibit equally favorable hemodynamic performance with minimal pressure gradient, both at rest and under stress conditions.

The CarboMedics valve: midterm follow-up with analysis of risk factors

BACKGROUND

This study examined the midterm results with the CarboMedics prosthetic valve.

METHODS

From 1987 through 1991 a total of 569 patients received the CarboMedics prosthesis.

RESULTS

Early mortality was 4.9% and related to emergency operation, presence of diabetes mellitus, coronary artery disease, preoperative New York Heart Association class, duration of cardiopulmonary bypass, and aortic cross-clamp time. Midterm follow-up with respect to mortality was 100% complete. All patients were followed up in the hospital after 1 year. In addition 86% of the patients responded to a questionnaire. Mean follow-up was 3 years (range, 0 to 5.6 years). Cumulative survival at 1 and 4 years was 91.2% +/- 1.2% and 83.7% +/- 1.8%, respectively. Five patients experienced obstructive valve thrombosis (0.3%/patient-year), 16 patients had major thromboembolic events (0.9%/patient-year), and 10 patients had major warfarin-related bleeding (0.6%/patient-year) requiring hospitalization or blood transfusions. Eight patients were reoperated on for paraprosthetic leak (0.4%/patient-year). Prosthetic valve endocarditis developed in 4 patients (0.2%/patient-year). No structural valve failure was observed.

CONCLUSIONS

Midterm follow-up demonstrates that the CarboMedics mechanical prosthesis is reliable and has an acceptable rate of valve-related complications.

Incidence and frequency of cerebral embolic signals in patients with a similar bileaflet mechanical heart valve

BACKGROUND AND PURPOSE

The aim of this study was to determine the incidence and frequency of cerebral embolic signals in a patient population with the same mechanical heart valve using transcranial Doppler examination. Furthermore, it aimed to identify patient and valve characteristics that correlated with the occurrence of these signals.

METHODS

Ninety-two patients with Carbomedics valves and 15 healthy control subjects took part in the study. Thirty-six patients were examined before and immediately after valve implantation (group 1), 34 patients 1 year after surgery (group 2), and 22 patients 5 years after surgery (group 3). Cerebral embolic signals were detected using transcranial Doppler monitoring of the right middle cerebral artery.

RESULTS

Asymptomatic cerebral embolic signals were detected in 87% of the total 92 patients, in 77.8% of group 1 patients, in 91.2% of group 2 patients, and in 95.5% of group 3 patients. No cerebral embolic signals were detected in group 1 patients before surgery or in control subjects. The incidence (P = .04) and frequency (P = .002) of cerebral embolic signals increased significantly with longer duration of valve implantation. A significant positive correlation was also found between frequency of cerebral embolic signals and valve size (r = .4326, P = .00001). Median frequency of embolic signals in patients with a history suggestive of cerebrovascular events (n = 14) was 60 signals per hour compared with 11 signals per hour in those with no such history (n = 42; P = .04).

CONCLUSIONS

The incidence and frequency of cerebral embolic signals increased with the duration of valve implantation. The frequency of these signals also was dependent on valve size. Patients who had experienced cerebrovascular symptoms had a higher frequency of cerebral embolic signals compared with those with no such signals. These results should be interpreted with caution but suggest that this method could be of help in assessing the risk of stroke in prosthetic heart valve patients and that prospective clinical studies should now be carried out.

The CarboMedics "top hat" supraannular prosthesis in the small aortic root

Twenty-three patients, 11 men and 12 women, with a mean age of 64 (range, 34 to 78) underwent aortic valve replacement (AVR) with a CarboMedics "Top Hat" supraannular prosthesis between March 1993 and August 1994. The top hat supraannular prosthesis, a standard bileaflet valve with the cuff transferred to the valve inflow level, allowed implantation of 21-mm, 23-mm, and 25-mm valves, where a standard 19-mm or 21-mm valve would have usually been placed. One patient who had been in preoperative cardiogenic shock died in the perioperative period. Another had an intraoperative cerebral embolism with permanent impairment. Follow-up on 22 of 23 patients over a mean period of 9 months revealed mean Doppler gradients of 18 +/- 6 mmHg, 15 +/- 2.8 mmHg, and 11 mmHg, for the 21-mm, 23-mm, and 25-mm valves, respectively. Functional improvement was noted, with 17 patients in New York Heart Association (NYHA) Class I and 6 in NYHA Class II, postoperatively, compared with 0 in Class I, 9 in Class II, 10 in Class III, and 4 in Class IV, preoperatively. One patient showed reduced postoperative ventricular function with fractional shortening below 25%. Pandiastolic regurgitation intrinsic to the valve graded as slight was noted in all patients. Other postoperative complications included one patient with anticoagulant-related gastrointestinal bleeding and one other with prosthetic valve endocarditis successfully treated with antibiotics. The CarboMedics top hat valve allows a gain in prosthesis size of 2 mm to 4 mm in the aortic position over standard prostheses, resulting in favorable postoperative hemodynamics.

Doppler echocardiographic comparison of small (19 mm) bileaflet and pericardial heart valve prostheses in aortic position

The resting haemodynamics of five types of small (19 mm) aortic valve prosthesis (2 bileaflet, 3 pericardial) were evaluated with Doppler echocardiography in 43 patients. Two received St Jude Medical and six CarboMedics bileaflet valves and 35 were given bioprostheses--16 Ionescu-Shiley, four Mitroflow and 15 Labcor-Santiago. No significant differences in peak or mean transvalvular pressure drop or in effective valve area were found between the bileaflet and the pericardial valves or among the three types of bioprosthesis. All but one of the bileaflet prostheses showed a characteristic regurgitation pattern, with two lateral and one central jet, and 16 (46%) of the bioprostheses showed central regurgitation, but in no case were these jets haemodynamically significant. Thus the 19 mm bileaflet and the studied pericardial prostheses all have satisfactory resting haemodynamics, and all are suitable for implanting in small aortic roots.

Performance of 96 CarboMedics valve replacements in 75 patients less than twenty-one years of age

Valve replacement still represents a problem in the very young patient. Between July 1988 and November 1993, 96 CarboMedics mechanical valves were implanted in 75 patients with a mean age of 11.76 years (range, 5 months to 20 years). The mean preoperative New York Heart Association functional class was 3.2, and 89.3% of the patients were in sinus rhythm. The cause was rheumatic in 60%, congenital in 24%, and infective in 12%. Mitral valve replacement was undertaken in 43 patients, aortic in 11, and mitroaortic in 21. Among the 18 patients with congenital defects, 13 required simultaneous repair of their complex lesions. The hospital mortality was 12% (9 patients). Cause and age were significant factors responsible for mortality. The mortality was 27.8% for patients with congenital disease and 6.7% for those with rheumatic defects (p = 0.0365); it was 40% for patients younger than 2 years, 14.3% for those between 3 and 10 years old, and 5.9% for those older than 10 years (p = 0.0108). The maximum follow-up was 54 months (mean, 18 months). There were 10 late deaths (15.15%). No embolic events occurred. All patients were on anticoagulation therapy except 2 who were on antiaggregant therapy. One of them underwent successful reoperation for treatment of mitral prosthetic thrombosis. Three reoperations were performed: one for thrombosis, one for perivalvular leak, and one for endocarditis. The total actuarial survival was 68.19% +/- 7.02%. Freedom from embolism was 100%; from thrombosis, 96.72% +/- 3.22%; from severe hemorrhage, 94.94% +/- 3.67%, and from reoperation, 83.07% +/- 9.51%.

Four-year experience with the CarboMedics valve: the North American experience. North American team of clinical investigators for the CarboMedics prosthetic heart valve

A multicenter prospective trial of the CarboMedics valve was initiated in July 1988. Twelve North American centers were included for the purpose of establishing the safety and efficacy of this new rotatable, bileaflet, pyrolytic-Carbon prosthesis. The study included 786 patients (using 891 valves) enrolled between July 1988 and August 1992. There were 447 male and 339 female patients from ages 2 to 83 years. Of the 618 primary replacement operations (including double valves), 393 were aortic and 292 were mitral valve replacements. Mean follow-up time was 16.1 months; 94.7% of patients had completed documentation up to and including one year. New York Heart Association functional class was III or IV for 84.4% of patients preoperatively, and I and II in over 96% of patients for the first three postoperative years. Survival for the entire group was 93% (622) at 1 month, 89% (504) at 1 year, 87% (213) at 2 years, and 85% (41) at 3 years. There were no significant survival differences between primary and repeat replacements or between aortic, mitral, and double-valve replacements. Primary replacement patients with concomitant procedures (n = 241) had slightly decreased survival rates compared with those who underwent isolated procedures (isolated survival rate, 92% [98]; concomitant procedure survival rate, 81% [59] at 2 years; p = 0.002). There was no valve failure. Linearized rates (events per 100 patient-years) in primary replacement patients after 30 days included the following: thrombosis, 0.39; thromboembolism, 0.92; hemolysis, 0.53; anticoagulant-related hemorrhage, 2.36; paravalvular leak, 0.92; endocarditis, 0.53; reoperation, 0.92; and explantation, 0.66.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiographic assessment of artificial heart valves: British Society of Echocardiography position paper

Images

CarboMedics valve in congenital heart disease. Midterm follow-up study of 14 patients

In 14 patients aged 5-329 (mean 131) months a CarboMedics valve was implanted because of congenital heart disease. The preoperative NYHA function class was III-IV in ten cases. Seven aortic and seven atrioventricular valves were replaced without early mortality. All patients were followed up, with mean observation time 27 months (total 384 months). One of the 14 patients died of heart failure 10 months postoperatively. Thrombosis occurred in four valves, three in tricuspid and one in mitral position. In all patients who received only warfarin, anticoagulation was demonstrably inadequate. Consequently we now recommend antiplatelet medication in addition to warfarin for children with atrioventricular mechanical valve replacement. In our experience the complication rate with CarboMedics prosthesis is acceptable, provided that anticoagulant therapy is adequate.

Echocardiographic description of the CarboMedics bileaflet prosthetic heart valve

OBJECTIVES

The aim of this study was to describe the echocardiographic appearance of the normal CarboMedics prosthesis in the aortic and mitral positions.

BACKGROUND

Echocardiography is the standard method of assessing prosthetic valves. However, new valve designs may still be marketed without an accompanying echocardiographic description. The CarboMedics prosthesis is in widespread use, but few noninvasive hemodynamic data have been published.

METHODS

Echocardiography was performed in 147 patients with a total of 96 normally functioning CarboMedics prostheses in the aortic position and 75 in the mitral position; in 24 patients, valves were implanted in both positions. The following variables were measured: peak and mean transvalvular velocities, peak and mean instantaneous gradient estimated from the modified Bernoulli equation, aortic acceleration slope, pressure half-time, transvalvular flow and effective orifice area using the continuity equation. Patterns of regurgitation were observed by transthoracic study in all valves and by transesophageal study in selected mitral valve prostheses.

RESULTS

For the aortic valve prostheses, estimated mean gradient ranged between 6 and 19 mm Hg. Effective area differed markedly among the anulus diameters (p < 0.001), with a mean value of 1 cm2 for the 19-mm valve and 2.6 cm2 for the 29-mm valve. For the mitral valve prostheses, mean gradient ranged from 3 to 7 mm Hg. There were a total of four washing leaks, one on either side of each pivotal point, and these lasted throughout systole or diastole. One jet was commonly more prominent than the other three.

CONCLUSIONS

The CarboMedics prosthesis offered relatively little resistance to forward flow except at small anulus diameters. The washing jets were prominent and would be easy to misdiagnose as a sign of paraprosthetic regurgitation.