Influence of prosthesis size and left ventricular mass on left ventricular diastolic reserve in patients with aortic valve prostheses.

BACKGROUND AND AIM OF THE STUDY: The study aim was to determine the influence of valve size and left ventricular (LV) mass on long-term LV diastolic reserve in patients subjected to aortic valve replacement for stenosis. METHODS: Seventy-four patients (33 women, 41 men; mean age 64 years) after aortic valve replacement with 40 pericardial bioprostheses and 34 bileaflet mechanical prostheses were studied. All valves were of nominal size 19, 21 or 23 mm. The patients were studied by Doppler echocardiography, at rest and during peak effort, between 12 and 47 months after valve replacement. RESULTS: All patients achieved significantly increased heart rate, blood pressure and cardiac output in response to effort. Effort also significantly modified transvalvular pressure drops and valve areas. The mean diastolic reserve was 29.3 ml, and mean stroke volume reserve 23.2 ml; in neither case were there any significant differences between valve types, or among valve sizes. CONCLUSION: At about one year after surgery, the diastolic reserve of patients subjected to aortic valve replacement on account of stenosis was considerable, and independent of valve size. Despite the persistence of LV hypertrophy after valve replacement, LV diastolic function during effort was similar to that of the normal heart.

Experimental and clinical evaluation of formalin containing pericardial bioprostheses for replacement of infected valves.

In 1988 we quantified the adherence of two Staphylococcus epidermidis strains to glutaraldehyde-fixed bovine pericardium and teflon. The pericardium was used with and without prior rinsing to remove the preservative formaldehyde. Bacterial adherence was not detected on non-rinsed pericardium, and it was significantly less on rinsed pericardium than on teflon (p < 0.001). In view of these results, we have since then implanted 31 pericardial bioprostheses without rinsing them in 29 patients with active bacterial endocarditis. Valve infection reoccurred in two patients (6.7%) and two patients developed early periprosthetic leaks in the absence of re-infection. No adverse clinical or biochemical findings attributable to residual aldehydes have been observed.

[Thromboembolism with the Ionescu-Shiley bovine pericardial bioprosthesis. Long-term results (11 years)]. / Tromboembolismo con la bioprótesis de pericardio bovino Ionescu-Shiley. Resultados a largo plazo (11 años).

With the aim to asses the thrombogenicity of "treated" bovine pericardial tissue, the incidence of thromboembolism with Ionescu-Shiley pericardial bioprostheses was analyzed in 349 operative survivors since January 1977. A total of 376 valves were available for the study. Mean age was 59 years. Preoperatively atrial fibrillation was present in 68.2% (91.7% of the mitral replacement group) and 62% were in NYHA functional class III-IV; in 10.6% previous embolism had been documented. Early anticoagulation (8-12 weeks) was administered in the first 232 patients (113 mitral replacements, 98 aortic replacements and 21 multiple replacements) and the rest of the patient population had no anticoagulation at all. Thromboembolic events were documented in 13 patients (3.72%) or 0.84% per patient/annum (1.49% per patient/annum for mitral and multiple replacements and 0.13% per patient/annum for aortic replacements). Early thromboembolism was detected in 6 patients (3 months after surgery), all in anticoagulated patients, three being in sinus rhythm. No valve thrombosis was detected in this series. Three patients with late thromboembolism were in NYHA functional class III-IV. Ten thromboembolic events were central (1 died and three had permanent neuro-residua). In two the location was peripheral and another one in the kidney. The Ionescu-Shiley pericardial bioprosthesis after 11 years has demonstrated a low thrombogenicity in the absence of chronic anticoagulation. Early anticoagulation does not influence the rate of thromboembolism during this period and therefore we believe that this therapeutic approach is not justified despite the presence of risk factors.