ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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To allow remodeling of the annulus while respecting natural three dimensional annular movements during mitral valve repair, a new annuloplasty ring (St Jude Medical [SJM]-Séguin annuloplasty ring) was developed. This ring has variable flexibility; that is, it is sufficiently rigid on the anterior portion to maintain intercommissural distance, and sufficiently flexible on the posterior portion to respect left ventricular function and natural three dimensional annular mobility. Fifty patients operated on for pure mitral regurgitation between January, 1994 and June, 1995 were studied. ⋯ All are well, in New York Heart Association functional Class I. Echocardiography showed a mean 0.4 +/- 0.3 mitral regurgitation, absence of any systolic anterior motion, and satisfactory mobility of the annuloplasty ring after the movements of the natural annulus, including non planar deviation. These preliminary results suggest that this annuloplasty ring 1) provides excellent correction of annular dilatation and remodeling of the annulus, 2) avoids systolic anterior motion observed with rigid rings, and 3) preserves physiologic three dimensional annulus motion.
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To estimate the effectiveness of pulsatility in end-organ microcirculation after cardiogenic shock, experimental studies using swine were done. Cardiogenic shock was produced in 14 pigs by ligating the left anterior descending branches so that mean aortic pressure dropped to 60% of the control value. After inducing shock, left atrial to ascending Ao bypass was initiated. ⋯ However, liver tissue flow, renal cortex flow, and stomach mucous flow in Group P was significantly higher than those of Group NP after support (p < 0.05). In addition, arterial blood ketone ratio in Group P was 0.61 +/- 0.13 vs 0.39 +/- 0.06 in Group NP, a significant difference (p < 0.05). These results suggest that in uneven blood flow distribution of end organs after cardiogenic shock, pulsatility was effective in improving and maintaining function and microcirculation of end organs, preventing multiorgan failure.
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Comparative Study
Validation of a novel ultrasound dilution method to measure cardiac output during hemodialysis.
A method to measure cardiac output (CO) based on ultrasound velocity dilution during hemodialysis was validated in an animal model against direct measurement using a transit time technique and a calibrated pump. In two anesthetized pigs, a 20 mm transit time ultrasound flow probe was placed on the ascending aorta to measure CO, and the right femoral artery and vein were cannulated for hemodialysis access. The dual sensor HD01 Hemodialysis Monitor was positioned on the arterial and venous tubing lines for measurement of cardiac output by ultrasound velocity dilution (COUD) by intravenous injections of 10-20 ml isotonic saline at 37 degrees C. ⋯ The COUD (n = 9) was compared with cardiac output as measured by pump flow (COP). A linear relationship was observed between COUD and COT (COUD) = 0.948 x COT + 0.086 L/min, r = 0.95), and between COUD and COP (COUD = 1.06 x COP-0.327 L/min, r = 0.99). Thus, cardiac output measured by ultrasound velocity dilution during hemodialysis is in good agreement with well established, but invasive, transit time and pump standards.
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The authors used quantitative gamma scintigraphy to evaluate the influence of nitric oxide gas on platelet and neutrophil deposition in Cobe Duo microporous oxygenators during cardiopulmonary bypass (CPB). The effects of nitric oxide gas on circulating platelet and neutrophil counts and platelet function also were assessed. Animals were prepared by standard methods. ⋯ Neutrophil adhesion tended to be lower, and circulating platelet and neutrophil counts tended to be higher with nitric oxide gas infusion. Results of in vitro aggregometry studies using rabbit platelets indicate that the class V phosphodiesterase inhibitor zaprinast can strongly enhance the inhibitory effects of nitric oxide. The authors conclude nitric oxide gas is a promising platelet sparing agent in the setting of CPB.