A STABLE OVINE CONGESTIVE-HEART-FAILURE MODEL - A SUITABLE SUBSTRATE FOR LEK VENTRICULAR ASSIST DEVICE ASSESSMENT

Similarities in coronary circulation and heart size of sheep to that o f humans are specific advantages of a sheep model of congestive heart failure (CHF). CHF was created in 11 sheep (51 +/- 4 kg) by selective sequential intracoronary injection of 90 mu m microspheres under 1.5% isoflurane anesthesia. Hemodynamic characteristics were assessed at ba seline, 4 weeks after establishment of CHF (ejection fraction [EF] < 3 5%, n = 11), and 26 weeks (n = 7) later. Baseline echocardiographic EF was 59 +/- 5% and fell to 26 +/- 5% after 5 +/- 2 embolizations. The left ventricular (LV) pressure-volume relationship showed stable decre ases in LV end-systolic elastance (Ees) and preload recruitable stroke work. Intravenous infusion of dobutamine increased Ees from 2.8 +/- 1 .7 to 4.3 +/- 2.2 and 4.5 +/- 1.4 mmHg/ml at heart rates of 140 and 16 0/min, respectively, at baseline. Increases of Ees (from 1.3 +/- 0.5 t o 2.3 +/- 0.7 and 1.9 +/- 0.5 mmHg/ml at heart rates of 140 and 160/mi n, respectively) with dobutamine under CHF conditions did not exceed E es values at baseline without dobutamine. This response to dobutamine infusion did not change 26 weeks after establishment of CHF. This stab le ovine CHF model is proposed for studies on the long-term effects of cardiac assist devices.