Clinical and hemodynamic results of cardiac valve replacement with the Monostrut Björk-Shiley prosthesis

Long-term experience with the Bjork-Shiley Monostrut tilting disc valve

The Bjork-Shiley Monostrut valve is tilting disc mechanical valve prosthesis. This study was designed to present the long-term outcome of our experience. One hundred and thirty-seven Bjork-Shiley Monostrut valves were implanted in 101 consecutive patients from November 1983 to February 1990. There were 60 male and 41 female with mean age of 34.5 yr at the time of operation. Fifty-nine patients underwent single valve replacement, 38 had double valve, and 4 had triple valve replacement. There were six in-hospital deaths (5.9%): three from cardiopulmonary bypass weaning failure and one each from septic shock, sudden cardiac arrest, and uncontrollable bleeding. Mean duration of follow-up was 181.2+/-76.2 months. Overall survival was 86.2% at 15 yr and 83.1% at 20 yr. Patients with mitral valve replacement had 93.5% and 90.2% cumulative survival at 10 and 15 yr, respectively, while patients with aortic valve replacement had 91.1% and 86.5% cumulative survival at 10 and 15 yr. Two groups had no significant difference in survival. Double valve replacement patients had 92.2% and 84.0% survival at 10 and 15 yr, respectively. There were no significant differences in survival between the single and double valve replacement groups. Freedom from thromboembolism was noted in: 97.8%, 97.8%, 96.4% and 87.8% at 5, 10, 15 and 20 yr, respectively. Absence of endocarditis was noted in 98.6% and 94.8% at 15 and 20 yr. Absence of reoperation was 92.5% at 20 yr. In conclusion, the Bjork-Shiley Monostrut valve is reliable, with a similar incidence of valve-related morbidity as in other mechanical valves.

Ministernotomy versus median sternotomy for aortic valve replacement: a prospective, randomized study

BACKGROUND

Minimally invasive aortic valve replacement reduces surgical trauma and, supposedly, postoperative pain, blood loss, and length of stay. A prospective, randomized study was designed to prove these theoretical advantages.

METHODS

Forty patients undergoing isolated, elective aortic valve replacement were randomized into two equal groups. Patients in group M underwent aortic valve replacement through a ministernotomy (reversed L or reversed C). In group S, a median sternotomy was used. The anesthetic and surgical protocol was identical for both groups. Pain was evaluated on a daily basis. Pulmonary function tests were performed preoperatively and before hospital discharge in all patients.

RESULTS

There were two deaths in each group. Cross-clamp time was longer in group M: 70 +/- 19 minutes versus 51 +/- 13 minutes in group S (p = 0.005). There were no statistically significant differences between groups M and S in pump time (95 +/- 20 minutes versus 83 +/- 19 minutes), extubation time (9.9 hours in both groups), chest drainage (479 +/- 274 mL/L 24 hours versus 355 +/- 159 mL/24 hours), transfusion requirements (27% in both groups), pain evaluation (1.34 +/- 1.3 versus 2.15 +/- 1.5), length of stay (6.2 +/- 2.3 days versus 6.3 +/- 2.5 days), and cosmetic appraisal. Forced vital capacity decreased 26% from preoperative reference values in group M and 33% in group S (p = not significant). Forced expiratory volume in 1 second decreased 22% and 35%, respectively (p = not significant).

CONCLUSIONS

This study has failed to prove the theoretical advantages of minimally invasive aortic valve replacement. With this technique, cross-clamp time is longer than with a median sternotomy.

The Spanish Monostrut Study Group: a ten-year experience with 8,599 implants

BACKGROUND

The Monostrut valve is a pyrolytic carbon, tilting-disc prosthesis with no welds. After the first implantation in Spain in May 1983, the Spanish Monostrut Study Group was established to evaluate prospectively the performance of the valve using uniform protocols.

METHODS

During a 10-year period, 8,599 Monostrut valves were implanted in 7,317 patients in 22 centers. Mean age was 53.3 +/- 11 years. Of the total group, 3,229 underwent aortic valve replacement, 2,806 had mitral valve replacement, and 1,282 had double valve replacement. Follow-up was 96% complete, with a mean period of 4.3 years and a total of 29,155 patient-years.

RESULTS

The operative mortality rate was 7.2%. The 10-year probability of freedom from valve-related complications and linearized rates (event/100 patient-years in parentheses) were as follows: structural deterioration, 100% (0); nonstructural dysfunction, 96% +/- 0.5% (0.51); thromboembolism, 82.9% +/- 1.5% (1.32); anticoagulant-related hemorrhage, 87.6% +/- 1.4% (0.98); and prosthetic valve endocarditis, 96.1% +/- 0.5% (0.48). There were five obstructive valve thromboses (0.017/100 patient-years). Actuarial freedom from reoperation was 95% +/- 0.5% at 10 years. Actuarial freedom from all valve-related morbidity was 70.2% +/- 1.6%; freedom from all valve-related morbidity and mortality (including operative and sudden deaths) was 62.6% +/- 2% (70.1% +/- 2% for aortic valve replacement, 56.9% +/- 2% for mitral valve replacement, and 59.8% +/- 3% for double valve replacement; p < 0.0001). Clinically, 5,988 patients (94%) are in New York Heart Association class I-II.

CONCLUSIONS

The Monostrut valve has shown no structural failures and a low rate of valve-related complications over a 10-year period in a large patient population.

Exercise hemodynamics in small (< or = 21 mm) aortic valve prostheses assessed by Doppler echocardiography

Exercise Doppler echocardiography was used to assess hemodynamics in 25 patients with a < or = 21 mm aortic valve prosthesis (14 with a Medtronic-Hall 21 mm valve, three with a Medtronic-Hall 20 mm valve, three with a Sorin 21 mm valve, one with a Duromedics 21 mm valve, and four with a Carpentier-Edwards 21 mm valve). A symptom-limited upright bicycle exercise test was performed, and Doppler gradients were recorded during exercise. Gradients increased with exercise from 30 +/- 8/16 +/- 4 mm Hg (peak/mean) at rest to 46 +/- 12/24 +/- 7 mm Hg during exercise; both p < 0.001. Mean exercise gradient exceeded 30 mm Hg in five patients, and the highest mean gradient recorded was 37 mm Hg. Within the group of mechanical valves, gradients at exercise were similar for different types of valves. A linear relationship was found between gradients at rest and during exercise (peak r = 0.75, mean r = 0.77; both p < 0.001). Additional findings were midventricular velocities exceeding 1.5 m/sec in late systole in 10 patients (40%) and intraventricular flow (> or = 0.2 m/sec) toward the apex during isovolumic relaxation in 11 patients (44%). The patients with these velocity patterns had significantly smaller left ventricular cavities (end-diastolic diameter 39.8 +/- 4.8 vs 46.5 +/- 4.2 mm, p < 0.01; end-systolic diameter 24.2 +/- 3.0 vs 28.5 +/- 4.5 mm, p = 0.013).(ABSTRACT TRUNCATED AT 250 WORDS)

Eight years' experience with the Medtronic-Hall valve prosthesis

During the period January 1981 to September 1986, 444 Medtronic-Hall heart valve prostheses were implanted in 351 patients (mean age, 45 +/- 10 years) mainly for rheumatic valve disease (63.2%). Most of the patients were in New York Heart Association functional class III. Concomitant surgical procedures, mainly conservative tricuspid or mitral procedures or coronary artery bypass grafting, were performed in 101 patients (28.7%). Single-valve replacement was performed in 262 patients (74.6%) (aortic in 117 patients, mitral in 143, and tricuspid in 2), double-valve replacement in 85 (24.2%) (mitral and aortic in 83 and mitral and tricuspid in 2), and triple-valve replacement in 4 (1.1%). Hospital mortality was 6.2%. Follow-up was 97.7% complete. The overall actuarial 8-year survival rate was 77.2%. The linearized incidence of valve-related complications was as follows: thromboembolism, 1.5%/patient-year; reoperation, 1.5%/patient-year; endocarditis, 1.25%/patient-year; hemolysis, 0.52%/patient-year; anticoagulant-related hemorrhage, 0.39%/patient-year; and noninfection-related paraprosthetic leak, 0.33%/patient-year. There were no instances of structural failure. We conclude that after 8 years of follow-up, the Medtronic-Hall valve prosthesis has an excellent clinical performance and a low range of valve-related complications.