Hemodynamic evaluation of the integral monostrut Björk-Shiley prosthesis in the aortic position

Patient-prosthesis mismatch and surgical aortic valve replacement outcomes: Retrospective analysis of single-center surgical data

BACKGROUND

Patient-prosthesis mismatch (PPM) has been identified as a risk factor for mortality and reoperation in patients undergoing surgical aortic valve replacement (SAVR). We present a retrospective analysis of risk factors for PPM and the effects of PPM on early postoperative outcomes after SAVR.

METHODS

Chart review was conducted for patients (N = 3003) undergoing SAVR. PPM was calculated from valve reference orifice areas and patient body surface area. Logistic regression was used to analyze risk factors for PPM and develop a risk score from these results. Regression was also conducted to identify associations between projected PPM status and postoperative outcomes.

RESULTS

Risk factors for PPM included female sex, higher body mass index (BMI), and use of the St. Jude Epic valve. Patients receiving St. Jude trifecta valves or mechanical valves were less likely to have predicted PPM. We developed a risk score using BMI, sex, and valve type, and retrospectively predicted PPM in our cohort. Mild PPM (odds ratio [OR] = 2.267), severe PPM (OR = 2.869), male sex (OR = 2.091), and younger age (OR = 0.940) were all predictors of SAVR reoperation, while aortic root replacement was associated with reduced reoperation rates (OR = 0.122). Severe PPM carried a risk of in-hospital mortality (OR = 3.599), and moderate PPM carried a smaller but significant risk (OR = 1.920). Other factors increasing postoperative morbidity and mortality included older age, renal failure, and diabetes.

CONCLUSION

PPM could be retrospectively predicted in our cohort using a risk calculation from sex, BMI and valve type. We conclude that all degrees of PPM carry risk for mortality and reoperation.

Incidence and influence of prosthesis-patient mismatch after reoperative aortic valve replacement: a retrospective single-center study

Background

Reoperative aortic valve replacement (AVR) is associated with increased mortality compared with initial surgery, and a smaller valve might be implanted during repeat AVR (re-AVR; AVR after prior AVR). We describe the clinical outcomes and incidence of prosthesis-patient mismatches (PPM) after reoperative AVR.

Methods

Among 113 patients who underwent reoperative AVR between 2007 and 2018, 44 underwent re-AVR and 69 underwent a first replacement of a diseased natural valve after any cardiac surgery except AVR (primary AVR). We then compared early and late outcomes, the impact of re-AVR on the effective orifice areas (EOA), and the incidence and influence of PPM on reoperative AVR.

Results

Hospital mortality was 2.7%, and the overall 1-, 3-, and 5-year survival rates were 95, 91 and 86%, respectively. The reference EOA of the newly implanted valve was smaller than that of the previous valve (1.4 ± 0.3 vs. 1.6 ± 0.3 cm², p < 0.01). The mean pressure gradient was greater (15.2 ± 6.4 vs. 12.7 ± 6.2 mmHg, p = 0.04) and indexed EOA was smaller (0.92 ± 0.26 vs. 1.06 ± 0.36 cm²/m², p = 0.04) during re-AVR than primary AVR, whereas the incidence of PPM was similar (38.7% vs. 34.8%, p = 0.87) between the groups.

Conclusions

The clinical outcomes of reoperative AVR were acceptable. Although the reference EOA of new implanted valves was smaller than that of previous valves, re-AVR did not increase the incidence of PPM. These findings might serve as a guide for future decisions regarding the surgical approach to treating degenerated prosthetic valves.

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 evaluation of prosthetic heart valves by Doppler echocardiography: comparison with catheterization studies

Although valve replacement remains the cornerstone of treatment for critical heart valve dysfunction, problems including thromboembolism, infection, and primary failure of the prosthesis remain. Resting studies of valve hemodynamics are sometimes insufficient to reveal valve dysfunction. Early studies using cardiac catheterization focused on changes in prosthetic function seen with various types of exercise or drug-induced stress. These studies suffered from an inability to adequately stress catheterized patients and were cumbersome to the patient and the investigator. With the introduction of Doppler echocardiography, however, studies could be performed after significant exercise with low risk and increased ease. Using echocardiography, reports of exercise-induced changes in aortic and mitral valve hemodynamics have appeared. Over 600 patients have been studied using Doppler echocardiography. In the aortic position, all prostheses studied have a mild peak instantaneous gradient (18-26 mmHg) at rest, which increases with exercise (35-63 mmHg). No significant differences between the four models of mechanical prostheses studied are found. The gradients achieved with exercise do not appear to be related to the heart rate achieved or duration of exercise. Smaller prostheses are associated with larger gradients; however, the correlation was not strong. All mitral valve prostheses studied are also mildly stenotic at rest (range of mean gradients 2.3-7.1 mmHg) and become moderately stenotic with exercise (range 5.1-16.5). Although the lowest gradients are seen with St. Jude Medical and Medtronic Hall prostheses, their gradients are not significantly less than with other valves.(ABSTRACT TRUNCATED AT 250 WORDS)

Value of exercise Doppler echocardiography in patients with prosthetic or bioprosthetic cardiac valves

Doppler echocardiographic evaluation of the prosthetic valve function is usually performed at rest, although this situation is not representative for patients' daily activities. Therefore, a symptom-limited Master 2-step test was performed in 61 asymptomatic patients with normal left ventricular function. No adequate Doppler signals were obtained in 5 of 61 patients (8%) within 60 second after termination of exercise. In patients with aortic valve prostheses (n = 24), heart rate increased from 74 +/- 10 to 105 +/- 18 beats/min, the maximal instantaneous gradient from 44 (range 22 to 90) to 68 (range 28 to 165) mm Hg (r = 0.89) and the mean gradient from 24 (range 12 to 50) to 39 (range 18 to 100) mm Hg (r = 0.90). In 6 of 11 patients with a maximal flow velocity ratio between the left ventricular outflow tract and the aortic valve prosthesis less than or equal to 0.25, the mean gradient increased to a value greater than or equal to 50 mm Hg after exercise, whereas in patients with a ratio of greater than or equal to 0.25, this never occurred. In patients with mitral valve prostheses (n = 39), heart rate increased from 80 +/- 12 to 116 +/- 14 beats/min and mean gradient from 6 (range 3 to 10) to 14 (range 6 to 25) mm Hg (r = 0.59). The correlation of the mean diastolic pressure gradient after exercise with pressure half-time was 0.66. Systolic pulmonary artery pressure at rest and after exercise could be determined in 22 of 39 patients (56%) and increased from 34 (range 20 to 70) to 57 (range 35 to 110) mm Hg. It is concluded that the response to exercise can, to a large extent, be inferred from Doppler parameters at rest, particularly in patients with aortic valve prostheses. The clinical implication of the high gradients found in some asymptomatic patients in the present study should be elucidated by follow-up studies.

Heart valve replacement with the Björk-Shiley Monostrut valve: early results of a multicenter clinical investigation

To evaluate the clinical performance of the Björk-Shiley Monostrut prosthesis, five centers combined their early experience. Between May, 1982, and June, 1985, 537 prostheses were implanted in 486 patients at these centers: 246 patients had aortic valve replacement (AVR), 163 underwent mitral valve replacement (MVR), and 47 had double-valve replacement (DVR). Thirty patients underwent other, more complex procedures. Concomitant cardiac procedures were performed in altogether 25%. Overall hospital (30 days) mortality was 5.1% (3.6% for AVR, 4.3% for MVR, 8.3% for DVR, and 16.6% for other procedures). The patients were followed up at 6- to 9-month intervals from 6 to 48 months (mean follow-up, 33 months). Follow-up was 99.6% complete. Late mortality was 7.2%. The three-year survival rate was 91.0% for AVR, 92.3% for MVR, and 76.2% for DVR. There was no structural failure of the prosthesis. No instances of valve thrombosis and fatal thromboembolism occurred in anticoagulated patients. The three-year incidence of freedom from thromboembolic events (including TIA) was 89.8% for AVR, 94.9% for MVR, and 90.2% for DVR. Preoperative and postoperative data for the assessment of mechanical hemolysis was available in 60% of the patients. The degree of mechanical hemolysis was low and did not change with time. Although the follow-up is still short, the Björk-Shiley Monostrut prosthesis appears to represent an improvement over previous Björk-Shiley models, particularly with regard to durability.