Optimal shape of prosthesis for tricuspid valve replacement.

Abstract

To develop an optimal prosthesis for use in the tricuspid valve, we determined the change in cardiac performance associated with the change in shape of the anulus of the tricuspid valve using a metal ring of variable flat ratio (defined as the long/short axis). In experiment I in an isolated autoperfusion model with six dogs, the left ventricular stroke work under a constant left atrial pressure of 7 mm Hg were, in grams per beat per minute, 11.88 +/- 0.52 with a flat ratio of 1.0, 11.88 +/- 0.70 with a flat ratio of 1.3, 16.23 +/- 0.61 with a flat ratio of 1.6, and 11.22 +/- 0.38 with a flat ratio of 2.3 (mean +/- standard error of the mean). The volume was significantly higher with a flat ratio of 1.6 than with the other ratios (p < 0.05). In experiment II with six dogs in vivo, the blood flow of the pulmonary trunk artery was 0.57 +/- 0.03 L/min with a flat ratio of 1.0, 0.66 +/- 0.03 L/min with a flat ratio of 1.6, and 0.58 +/- 0.03 L/min with a flat ratio of 2.3; the flow was significantly larger with a ratio of 1.6 than with the other ratios (p < 0.05). Right ventriculography was performed in five dogs. The percentage of radial shortening of the apex close to the acute margin was 19.4% +/- 3.1% with a flat ratio of 1.0 and 49.2% +/- 5.1% with a flat ratio of 1.6 (p < 0.05). In conclusion, the best hemodynamic results were obtained with a flat ratio of 1.6, which showed more advantageous hemodynamics than do the ratios of conventional circular prostheses.