Left ventricular function in experimental mitral regurgitation with intact chordae tendineae. Discussion

Left ventricular function in mitral regurgitation has typically been studied in models that either sever the chorale tendineae or create a ventriculoatrial shunt. These methods may have adverse effects on left ventricular function independent of the regurgitant lesion. An animal model of chronic mitral regurgitation was therefore developed that both preserves annuloventricular continuity and avoids the use of external shunts. A circular 0.16 to 0.24 mm/kg defect was created in the anterior mitral value leaflet of weanling sheep under direct vision with the aid of cardiopulmonary bypass. Six animals were studied preoperatively and immediately postoperatively (acute regurgitation group), and 20 animals were studied 8.1±0.2 (mean ± one standard deviation) months postoperatively (chronic regurgitation group)