Effect of a flexible ventricular restraint device on cardiac remodeling after acute myocardial infarction.

The effects of a flexible ventricular restraint device on left ventricular (LV) dilatation and hypertrophy after transmural infarction are examined in an ovine model. Left ventricular remodeling and dilatation occurs after extensive myocardial infarction. A flexible ventricular restraint made from a nitinol mesh was evaluated in adult female sheep (n=14). Cardiac magnetic resonance imaging scans and hemodynamic measurements were completed before and 6 weeks after anterior myocardial infarction. Treatment animals (n=7) received passive ventricular restraint concurrently with LV infarction; the others (n=7) served as controls. Increases in LV end-diastolic volume index were significantly less in the restraint group than in controls (0.20+/-0.41 vs 0.83+/-0.50 ml/kg, p<0.03). End-systolic volumes increased less in treatment animals (0.43+/-0.28 vs 0.90+/-0.38 ml/kg, p<0.03). Control hearts showed an increase in LV mass after infraction, whereas LV mass decreased in restrained hearts (0.14+/-0.19 vs -0.25+/-0.36 g/kg, p<0.03). Hemodynamic studies showed similar changes after infarction for the control and the device group. Gross and microscopic examination showed no device-induced epicardial injury. A flexible ventricular restraint device attenuated remodeling after acute myocardial infarction in sheep.