Early regional assessment of LV mass regression and function after stentless valve replacement: comparative randomized study.

Early regional performance and hypertrophy regression after stentless aortic valve replacement are still incompletely characterized. We compared early postoperative changes of segmental thickness and function after stentless and stented aortic valve replacement as assessed by cardiac magnetic resonance (CMR). In 16 patients randomly assigned to stented (Mosaic, 8 patients) and stentless (Freestyle, 8 patients) groups, 4 parallel short-axis images at the level of the apex (slice 4), midventricle (slices 2-3), and mitral valve (slice 1) were obtained with a 1.5 T CMR scanner (Magnetom Sonata, Siemens) before and 1 month after surgery. Cine images were obtained using an echo gradient sequence. Left ventricle mass was calculated as the difference between the left ventricular end-diastolic volume at the epicardial and endocardial borders multiplied by a myocardium density factor (1.05). Each slice was divided into 8 segments (octants) from anterior (octant I-II) to septal (octant V-VIII). A total of 32 segments encompassed the entire heart. From each of these elements end diastolic thickness and systolic function (fractional thickening) were calculated. In stentless valves significant reduction of septal octant thickness on the midventricular slice was noted. There was no difference in regional systolic function-segment thickening. In stented valves no segmental thickness changes were observed. In stentless valves there was early postoperative thickness reduction of septal segments at the midventricular level. However, this finding did not coincide with changes in segmental function.

Hemodynamic performance after stented vs stentless aortic valve replacement.

BACKGROUND: Stentless bioprostheses are anticipated to cause improved hemodynamics and increased longevity over stented bioprosthesis. We have compared echocardiographic analysis of stented bioprosthesis "Freestyle" with stented "Mosaic" bioprosthesis. Because of similar technology (0 pressure fixation, anticalcification) any differences may relate to stent. METHODS: Twenty-eight patients undergoing AVR were randomly assigned to receive either stented or stentless. Echocardiograms, by means of M-mode and Doppler were performed early, 3-6 months and 1 year postoperatively. RESULTS: The peak flow velocity was significantly lower in the stentless group, especially 1 week and 6 months after surgery. Mean transvalvular gradient dropped significantly in stentless group and did not change in stented group. EOA did not change significantly in either of groups. AoV velocity time integral was increasing in stentless group. LV mass had fallen significantly in both groups but degree of mass reduction was comparable. CONCLUSIONS: There are marked improvements of stentless valves hemodynamics. However it is not necessary equal to higher degree of LV mass reduction during 1 year follow-up.

"Mosaic" medtronic bioprosthetic valve replacement clinical results and hemodynamical performance.

BACKGROUND: We report the mid-term results of a prospective trial of a new bioprosthetic valve. The Mosaic bioprosthesis consists of porcine aortic valve that has been cross linked ed in glutaraldehyde solution under zero-pressure fixation and treated with alpha amino oleic acid to reduce the potential for calcification. METHODS: Mosaic bioprosthetic valve replacement was performed in 67 consecutive patients between January 1995 and August 1998. There were 37 patients having aortic valve replacement (AVR) and 30 having mitral valve replacement (MVR) who entered this study. The patients age ranged 56 to 86 years (mean 74.9); 38 were female and 29 were male; 44 were in NYHA grade 3 and 21 were NYHA grade 4. All mitral valve replacements were performed with total preservation of subvalvular apparatus. Echocardiographic assessment of valve and LV function were performed on 7th day, 6 months 1,2 and 3 years. RESULTS: There was no hospital mortality. 3 year survival was 85.9+/-5.9% for AVR and 100% for MVR. Freedom from antithromboembolic related haemorrhage has been 96.7% for MVR and 91.9% for AVR. Freedom from the transient neurological event was 96.7+/-3.3% for MVR and 100% for AVR Freedom from structural valve failure, permanent thromboembolism, thrombosis or endocarditis has been 100% for both AVR and MVR. In AVR group left ventricle mass, left ventricle mass index significantly decreased, when cardiac index and effective orifice area increased significantly during study period. Transvalvular gradient did not change. In MVR group transvalvular gradient, effective orifice area and cardiac index did not change. CONCLUSIONS: The valve was user friendly. The early results are very satisfactory. Echocardiography measurements after aortic valve replacement are showing very marked late postoperative remodelling of left ventricle. After mitral valve replacement there were exceptionally low transvalvular gradients, no left ventricle outflow tract obstruction.

Does simultaneous antegrade and retrograde cardioplegia improve functional recovery and myocardial homeostasis?

BACKGROUND: The purpose of our research was to evaluate the functional recovery and homeostasis of myocardium during simultaneous continuous retrograde and antegrade cardioplegia versus continuous retrograde cardioplegia. METHODS: Forty patients who underwent elective coronary artery bypass grafting (CABG) were prospectively assigned to two clinically matched groups and analyzed in respect to cardioplegia protocol. Group I consisted of 24 patients who received continuous retrograde blood cardioplegia; Group II consisted of 16 patients who received simultaneous continuous ante- and retrograde cardioplegia. Hydrogen ion release, carbon dioxide, lactate concentration oxygen content, and oxygen extraction were measured from coronary sinus effluent and from the arterial line before and after cross-clamping of the aorta. Median changes of these parameters were reported. Cardiac output was measured and left and right ventricle stroke works were calculated. Incidence of low cardiac output, ventricular fibrillation, raised cardiac enzymes, and ischemic changes on electrocardiogram (ECG) were noted. RESULTS: In the simultaneous group, oxygen content and oxygen extraction recovered well after cross-clamping. The same parameters did not recover to the same extent in the retrograde group. These changes were notable between groups. Hydrogen ion, carbon dioxide, and lactate releases were comparable between groups. Trend toward better recovery of left ventricle stroke work index was encountered in the simultaneous group. CONCLUSIONS: Viability of myocardium measured with oxygen utilization and functional recovery is better preserved with simultaneous antegrade and retrograde cardioplegia. However, there is no difference in anaerobic metabolism markers. Thus simultaneous ante- and retrograde cardioplegia is probably advantageous over retrograde alone.