Hemodynamic performance of the 21-mm St. Jude BioImplant prosthesis using dobutamine Doppler echocardiography

The Scandinavian multicenter hemodynamic evaluation of the SJM Regent aortic valve

Background

112 patients who received small and medium sized St.Jude Regent heart valves (19-25 mm) at 7 Scandinavian centers were studied between January 2003 and February 2005 to obtain non-invasive data regarding the hemodynamic performance at rest and during Dobutamine stress echocardiography (DSE) testing one year after surgery.

Material and methods

46 woman and 66 men, aged 61.8 ± 9.7 (18-75) years, were operated on for aortic regurgitation (17), stenosis (65), or mixed dysfunction (30). Valve sizes were 19 mm (6), 21 mm (33), 23 mm (41), 25 mm (30). Two patients receiving size 27 valves were excluded from the hemodynamic evaluation. Pledgets were used in 100 patients, everted mattress in 66 and simple interrupted sutures in 21. Valve orientation varied and was dependent on the surgeons' choice. 34 patients (30.4%) underwent concomitant coronary artery surgery.

Results

There were two early deaths (1.8%) and three late deaths, one because of pancreatic cancer. Late events during follow-up were: non structural dysfunction (1), bleeding (2), thromboembolism (2). At one year follow up 93% of the patients were in NYHA classes 1-2 versus 47.8% preoperatively.

Dobutamine stress echocardiography (DSE) was performed in a total of 66 and maximal peak stress was reached in 61 patients.

During DSE testing, the following statistically significant changes took place: Heart rate increased by 73.0%, cardiac output by 85.5%, left ventriclular ejection fraction by 19.6%, and maximal mean prosthetic transvalvular gradient by 133.8%, whereas the effective orifice area index did not change.

Left ventricular mass fell during one year from 215 ± 63 to 197 ± 62 g (p < 0.05).

Conclusion

The Dobutamine test induces a substantial stress, well suitable for echocardiographic assessment of prosthesis valve function and can be performed in the majority of the patients. The changes in pressure gradients add to the hemodynamic characteristics of the various valve sizes.

In our patients the St. Jude Regent valve performed satisfactory at rest and under pharmacological stress situation.

Evaluation of the hemodynamic performance of St. Jude mitral prostheses: a pilot study by dobutamine-stress Doppler echocardiography

In contrast to the widespread use of dobutamine stress Doppler echocardiography in the hemodynamic evaluation of the prosthetic valves in aortic position, it has been rarely, if ever, used for assessment of these valves in mitral position. Therefore, this pilot study was done to assess the hemodynamic performance of St. Jude prosthetic mitral valves (functional orifice area 25-31) with dobutamine-stress Doppler echocardiography. Twenty consecutive patients (13 women and 7 men, aged 23 to 42 years) who had undergone mitral valve replacement 6 to 4745 days previously and 16 healthy volunteers (5 women and 11 men, aged 18 to 42 years) underwent dobutamine-stress Doppler echocardiography. Dobutamine infusion was started at a rate of 5 microg/kg per minute and was increased by 5 microg increments at 3-minute intervals. Maximum and mean gradients as well as pressure halftime were measured at rest and at the end of each stage. The correlation between Doppler-derived variables versus the heart rate was assessed and a regression equation was obtained for each of them. A significant increase in blood pressure, heart rate, maximum and mean gradients was noted during dobutamine infusion in both groups. There was a significant positive linear correlation between the increasing transprosthetic mitral valvular maximum and mean gradients and the increments in the heart rate (G(max) = 4.47 + 0.093 [HR], r= 0.474, p<0.05) and (G(mean) = 3.0+0.003 [HR], r=0.2697, p<0.05), respectively, indicating the heart rate dependency of these parameters. Pressure halftime, on the other hand, had an inverse but linear relationship with the heart rate (PHT = 142 - 0.55 [HR], r= -0.577, p<0.05). Similar findings were found for the control group as well. Standard dobutamine-stress echocardiography can safely be performed in patients with St. Jude mitral valve prostheses. Single Doppler measurements of the pressure gradients and pressure halftime may yield erroneous conclusions regarding the function and size of these valves unless corrected for the patients simultaneous, online heart rate. The use of the regression equations obtained in this pilot study may help to partly overcome some of these difficult issues.

Patient-prosthesis mismatch is negligible with modern small-size aortic valve prostheses

BACKGROUND

Concern has been raised about residual significant gradients when small aortic prostheses are used, particularly in patients with large body surface areas. We studied the performance of six types of small aortic prostheses using dobutamine stress echocardiography.

METHODS

Sixty-three patients (mean age, 67 +/- 7 years) who had undergone aortic valve replacement 17 +/- 6 months previously were studied. Two bileaflet mechanical prostheses (St. Jude Medical and CarboMedics: sizes, 19 mm and 21 mm) and two biological prostheses (Medtronic Intact and St. Jude BioImplant: size, 21 mm) were evaluated. A graded infusion of dobutamine was given and Doppler studies of valve performance were carried out.

RESULTS

All prostheses except one biological valve had acceptable hemodynamic performance under stress. Using regression modeling, gradient at rest was the only variable found to predict gradient under stress (p < 0.001). Moreover, the most important predictor of gradient at rest was valve design, which accounted for 72% of the variance (p < 0.001). This relationship was independent of valve size (19 mm or 21 mm) or material (ie, mechanical or biological). Body surface area accounted for 4% of the variance in gradient only.

CONCLUSIONS

The main predictor of transprosthetic gradient is the inherent characteristics of each particular prosthesis, with relatively insignificant contribution from variations in body surface area. Patient-prosthesis mismatch is not a problem of clinical significance when certain modern valve prostheses are used.

Stress echocardiography in valvular heart disease

Stress echocardiography has been widely accepted as an important diagnostic and prognostic tool in the assessment of known or suspected coronary artery disease. Its use in valvular heart disease, to date, has been more limited, but is continuing to grow as the technology and the understanding of valvular disorders progress. In this article, we will review the current literature regarding the use of both exercise and pharmacological stress testing in conjunction with echocardiography in the settings of native and prosthetic mitral and aortic valve disease. We will also discuss the limitations of this modality and touch upon possible future areas of investigation.

Temporal variability of exercise Doppler echocardiography in patients with nonstented aortic bioprostheses

Temporal variability and reproducibility of Doppler-derived variables obtained during supine symptom-limited exercise was investigated in 26 patients who were in clinically and hemodynamically stable condition with normally functioning nonstented aortic bioprostheses (stentless porcine, n = 13; cryopreserved homografts, n = 13). All patients had normal systolic left ventricular function and underwent 2 similar exercise tests within 12 months (mean time interval 7.2 +/- 1.9 months). The coefficient of variation was 8% to 9% for primary Doppler-derived variables (ie, velocities and velocity time integrals) at rest and during exercise. The coefficient of variation for calculated maximal pressure difference was 16% at rest and 15% at peak exercise. Measurement variability assessed from repeated measurements from the same videotaped recording was approximately 2%. High reproducibility was shown for most variables with intraclass correlation coefficients of 0.85 or more. We conclude that Doppler echocardiography can be used in patients with nonstented aortic bioprostheses with the same high reproducibility during exercise as at rest. The results provide clinically useful information regarding temporal variability for Doppler-derived variables.

Manual debridement of the aortic valve in elderly patients with degenerative aortic stenosis

OBJECTIVE

We prospectively analyzed the short- and long-term results of manual debridement of the aortic valve in elderly patients with severe degenerative aortic stenosis.

METHODS

Between September 1988 and January 1997, 103 patients aged 73.7 +/- 6 years with degenerative aortic stenosis underwent the manual debridement technique. All had symptoms (angina or dyspnea, or both). Peak systolic gradient was 89 +/- 28 mm Hg. Forty-one patients (39.8%) had associated coronary artery disease necessitating revascularization.

RESULTS

Follow-up time was 42 +/- 21 months (range 3-98 months). The Kaplan-Meier estimated survival at 98 months was 50% (95% CI: 30%-70%). In-hospital mortality was 5.8% (6 patients), and late mortality was 21% (21 patients). No predictors of in-hospital mortality or of late mortality were detected. Nonfatal postoperative complications appeared in 25 patients (24%). At 8 years, freedom from endocarditis was 98% (95% CI: 95%-100%) and freedom from thromboembolic events was 99% (95% CI: 96%-100%). No patient required long-term anticoagulation as a result of the procedure. Fourteen patients (14%) required reoperation for aortic insufficiency (n = 5), restenosis (n = 8), and mitral regurgitation (n = 1). The probability of reoperation at 98 months was 23% (95% CI: 12%-35%).

CONCLUSION

Manual aortic valve debridement has low rates of in-hospital mortality, perioperative complications, and thromboembolic and infectious events and it offers freedom from anticoagulation. However, the incidence of restenosis and reoperation is high in the long term. It may therefore be regarded as an alternative in aged patients with favorable valve anatomy (no distortion and calcium deposits only on the aortic surface of the cusps), especially in those with a small aortic anulus, associated coronary artery disease, and/or contraindication for anticoagulation.