Medtronic Mosaic porcine bioprosthesis: assessment of 12-year performance.

BACKGROUND: The Mosaic porcine bioprosthesis (Medtronic, Inc, Minneapolis, Minn) was approved in 2000 by the US Food and Drug Administration. Clinical performance was evaluated in 6 centers. METHODS: From 1994 to 2000, 797 patients (mean age 69 years) had aortic valve replacement (AVR) and 232 (mean 67 years) had mitral valve replacement (MVR). Concomitant coronary artery bypass grafting was performed with aortic valve replacement (45.4%) and mitral valve replacement (43.5%). Mean follow-ups were 7.5 years for aortic position and 7.3 years for mitral position. RESULTS: Early mortalities were 2.8% for AVR and 3.0% for MVR. Late mortalities were 4.2%/patient-year for AVR and 5.1%/patient-year for MVR. Overall 12-year survivals were 55.8% ± 3.7% for AVR and 43.9% ± 7.4% for MVR. Twelve-year freedoms from valve-related mortality were 87.1% ± 3.1% for AVR and 82.5% ± 7.7% for MVR. Twelve-year freedoms from reoperation were 84.0% ± 3.3% for AVR and 82.5% ± 7.5% for MVR. Freedoms from structural valve deterioration (SVD) by explant reoperation at 12 years for AVR were 93.3% ± 2.6% for patients at least 60 years old and 75.9% ± 9.3% for patients younger than 60 years. Freedoms from SVD by explant reoperation at 10 years for MVR were 95.3% ± 7.8% for patients at least 70 years old and 84.0% ± 9.3% for patients younger than 70 years. Hemodynamic performance data at 1 year for AVR (sizes 21-27 mm) were mean systolic gradient range 13.7 ± 4.8 to 10.3 ± 3.2 mm Hg and effective orifice area range 1.5 ± 0.3 to 2.5 ± 0.4 cm(2). For MVR (sizes 25-31 mm), data were mean diastolic gradient range 6.7 ± 1.7 to 3.7 ± 0.9 mm Hg and effective orifice area range 1.9 ± 0.3 to 2.4 ± 0.6 cm(2). CONCLUSIONS: Overall performance of Mosaic porcine bioprosthesis to 12 years is satisfactory. Freedoms from SVD by explant reoperation were most satisfactory for aortic position in patients at least 60 years old and mitral position in patients at least 70 years old. Overall actuarial freedom from SVD by explant reoperation is encouraging for patients with MVR.

Phase I and Phase II oxygen uptake kinetics during atrioventricular dyssynchrony in chronotropically competent pacemaker patients.

OBJECTIVE: To elucidate the effects of atrioventricular (AV) dyssynchrony on phase I and phase II oxygen uptake (V(O2)) kinetics in chronotropically competent pacemaker patients during exercise of an intensity comparable to activities of daily living. DESIGN: Blinded patients completed sub-ventilatory threshold (VT) work rate (WR) cycle ergometry exercise in random order during asynchronous AV pacing (AV OFF) and synchronous AV pacing. SETTING: Tertiary care hospital in a major city. SUBJECTS: Six chronotropically competent male pacemaker patients (mean [+/- SD] age, 68 +/- 10 years) with high-degree AV block and varying cardiac histories. RESULTS: The phase I and phase II V(O2) amplitude response and gain (deltaV(O2)/WR ratio) were lower (p < 0.05) and the time course of phase II was slower (p < 0.05) during AV OFF; however, the O2 deficit was similar (p > 0.05) across pacing modes. The stroke volume index (SVI) was consistently lower (p < 0.05) during AV OFF pacing and was significantly correlated with the time course of phase II V(O2). A significant compensatory amplitude response in heart rate (HR) was observed in addition to a higher (p < 0.05) deltaHR/V(O2) ratio during AV OFF. Ventilatory responses were consistent with ventilatory-perfusion mismatching and perceived exertion was higher during asynchronous pacing. CONCLUSION: This study demonstrated that the contribution of SVI affects V(O2) kinetics and underscores the importance of the atrial contribution to ventricular filling and, consequently, to metabolic and hemodynamic responses. This study supports the theory of an O2 transport limitation and further implicates SV as a potential limiting factor during sub-VT exercise intensities that are comparable to those encountered in activities of daily living.