Medtronic Intact porcine bioprosthesis: clinical performance to seven years

Carpentier-Edwards Bioprosthesis: Structural Deterioration by Age Groups

The Carpentier-Edwards supra-annular porcine bioprosthesis (second generation prosthesis) was implanted in 2438 patients in 2482 operations between 1982 and 1992. The mean age of the population was 64 years with a range from 21 years to 89 years. There were 1334 aortic and 934 mitral valve replacements. The population was divided into five groups: 21 to 40 years (n = 132); 41 to 50 years (n = 189); 51 to 60 years (n = 454); 61 to 70 years (n = 849); and over 70 years (n = 858). There was no difference in sunival by valve position for age groups 21 to 40 years and 41 to 50 years. Sunival within the age groups 51 to 60 years, 61 to 70 years, and over 70 years was greater for patients with aortic compared with mitral and multiple valve replacements. The freedom from structural valve deterioration at 10 years for all age groups was highest for valves in the aortic position. Patients with valves in the mitral position had a higher freedom from structural valve deterioration at 10 years than those who had multiple valve replacement, although not all the differences were significant. There was a lower incidence of structural valve deterioration in the older age groups. We concluded that the use of the Carpentier-Edwards supra-annular porcine bioprosthesis for aortic valve replacement can be extended to patients over 60 years of age, while its use for mitral valve replacement can be extended to those above 70 years of age.

The Quebec Heart Institute: 50 years of excellence in cardiology

The Quebec Heart Institute was established in 1957 at the Laval Hospital in Sainte-Foy, Quebec. Since then, clinical and research activities have made this Institute one of the largest tertiary care cardiology centres in Canada. With its vast catchment area of more than 3,000,000 people, the Institute has developed a strong collaboration with referral physicians centred on clinical, teaching and research interests. The Institute pioneered several aspects of cardiac surgery, invasive cardiology, echocardiography, basic research and, more recently, a network of researchers and clinicians working in the field of 'metabolic cardiology'. The first 50 years of the Quebec Heart Institute are depicted in this overview, which will also introduce this special supplement to The Canadian Journal of Cardiology.

Medtronic freestyle valves in right ventricular outflow tract reconstruction

BACKGROUND

Various pulmonary valve substitutes, with their inherent limitations, have been used in children and young adults. We chose the Medtronic Freestyle (Medtronics, Minneapolis, MN) valve because of its excellent hemodynamics, known durability in adults, and design features that allow modifications during implantation.

METHODS

Over a 3 1/2 year period the Freestyle valve was implanted in 47 patients age 2 to 58 years (mean 14.2, median 12.0) in the pulmonary position. All patients had pulmonic stenosis and(or) insufficiency from previous operations for tetralogy (27), pulmonary atresia (6), truncus (4), or other diagnosis (10). The indication for surgery was pure pulmonary insufficiency in 11 patients, pulmonic stenosis in 3, and mixed stenosis and insufficiency in 33. Root replacement technique was used with additional enlargement of the pulmonary artery branches in 10 patients.

RESULTS

Intraoperatively, one patient sustained a right ventricle tear and one a circumflex coronary artery injury during the dissection. There was one postoperative death. Two patients developed late subvalvular pannus formation, one of whom required reoperation. One patient was found to have an echo gradient of 95 mm Hg due to decreased leaflet motion and underwent cardiac catheterization at which the peak systolic gradient was determined to be 50 mm Hg. He has not required reintervention during his 3 1/2 years of follow-up. The remaining 43 patients have minimal gradients or insufficiency. All surviving patients are in New York Heart Association (NYHA) Class I.

CONCLUSIONS

The Medtronic Freestyle valve is an attractive alternative for RVOT (right ventricular outflow tract) reconstruction in children. It is readily available, versatile, and has excellent hemodynamic characteristics. Although long term follow-up is not yet available, longevity of this prosthesis, and freedom from complications, will hopefully be superior to valves with stents.

European experience with the Mosaic bioprosthesis

OBJECTIVE

The purpose of this study was to prospectively evaluate the clinical and hemodynamic performance of the Mosaic bioprosthesis (Medtronic, Inc, Minneapolis, Minn).

METHODS

The stented porcine bioprosthesis combines the amino-oleic acid antimineralization treatment and the zero-pressure differential fixation technique for improved tissue durability. From February 1994 to May 1999, a total of 561 patients underwent valve replacement with the Mosaic bioprosthesis at 5 centers in Europe: 461 in the aortic and 100 in the mitral position. There were 261 women and 300 men; mean age at implantation was 70 years (range, 23-89 years). Mean follow-up was 2.9 years (range, 0-6.2 years), with a total follow-up of 1710.1 patient-years.

RESULTS

Postoperative mortality was 4.2% per patient-year, including a valve-related mortality of 0.4% per patient-year. The freedom from event rates in the aortic position at 5 years and in the mitral position at 4 years were, respectively, 96.6% +/- 1.1% and 94.9% +/- 3.3% for primary thromboembolism, 96.4% +/- 5.0% and 87.1% +/- 4.8% for antithromboembolic-related hemorrhage, 99.1% +/- 0.5% and 100% for thrombosed prosthesis, 98.8% +/- 1.2% and 100% for structural valve deterioration, 98.8% +/- 0.7% and 100% for nonstructural dysfunction, 98.4% +/- 0.6% and 94.4% +/- 3.8% for endocarditis, and 95.4% +/- 1.6% and 95.3% +/- 3.7% for explant and reoperation. Mean pressure gradient values at 5 years ranged from 7.5 to 15.9 mm Hg in the aortic position and at 4 years from 2.0 to 6.9 mm Hg in the mitral position across all valve sizes.

CONCLUSIONS

Clinical and hemodynamic performance of the Mosaic bioprosthesis were very satisfactory during the first 6 years after clinical introduction.

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.

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.

Freestyle valve experience: technical considerations and mid-term results

BACKGROUND

Many studies have demonstrated the superior hemodynamics of stentless porcine aortic valves compared to stented valves. This article describes the operative techniques and reviews our 5-year experience with the Medtronic Freestyle stentless valve.

METHODS

Between January 1993 and November 1997, 95 patients underwent implantation of the Medtronic Freestyle valve at a mean age of 76 years. All patients were seen at 6 months, 1 year, and annually thereafter for clinical assessment and Doppler echocardiography.

RESULTS

There were three operative and ten late deaths (two cardiac and eight noncardiac). Three strokes and four transient ischemic attacks occurred in the follow-up period. Four patients had bacteremia that was treated successfully with antibiotics. No patient required reoperation for valve-related problems. Serial echocardiograms revealed a decrease in mean systolic gradients across the valve during the first year and an increase in effective orifice areas. Ninety-one percent of patients had no, or trace, aortic insufficiency at the time of discharge and this has not increased over time.

CONCLUSION

The Medtronic Freestyle valve has excellent hemodynamics and good clinical results. In our experience, no patient has required reoperation in a 5-year follow-up.

Dynamic evaluation of the 21-mm Medtronic Intact aortic bioprosthesis by dobutamine echocardiography

BACKGROUND

High residual transvalvular gradients have been reported with the use of small Medtronic Intact aortic valve prostheses. The aim of this study was to evaluate the hemodynamic performance of 21-mm prostheses using dobutamine Doppler echocardiography.

METHODS

Ten patients (7 women; mean age, 79 years) who had undergone aortic valve replacement with 21-mm Medtronic Intact prostheses 19.1 +/- 9.9 (standard deviation) months previously were studied. Dobutamine infusion was started at a rate of 5 microg x kg(-1) x min(-1) and increased to 10 and 20 microg x kg(-1) x min(-1) 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 each valve were calculated, and peak and mean velocity and pressure drop across the prostheses were measured. Cardiac output was determined by Doppler measurement of flow in the left ventricular outflow tract.

RESULTS

Dobutamine stress increased heart rate and cardiac output by 68% and 65%, respectively (both p < 0.005), and mean transvalvular gradient increased from 19.1 +/- 5.1 mm Hg at rest to 33.2 +/- 7.7 mm Hg at maximum stress (p < 0.0001). Regression analyses demonstrated that maximum-stress gradient was independent of all variables except resting gradients (p < 0.004). Body surface area had no effect on the changes in cardiac output, effective orifice area, or transprosthetic gradient at maximum stress.

CONCLUSIONS

These data show that the 21-mm Medtronic Intact aortic prosthesis exhibits acceptable hemodynamic performance. Transvalvular gradients remained within a clinically acceptable range, both at rest and at maximum stress. Moreover, overall hemodynamic performance suggests that patient-prosthesis mismatch is unlikely to be a problem of clinical importance when this prosthesis is used.