PRECLINICAL EVALUATION OF A NOVEL, PNEUMATIC, VENTRICULAR ASSIST DEVICE (MEDOS(R) HIA-VAD(R)) UNDER PATHOPHYSIOLOGICAL CONDITIONS

To evaluate a new cardiac assist system, the Medos(R) HIA-VAD(R), we s tudied the effects of mechanical unloading on regional and global myoc ardial dysfunction. As a model for the regional temporary contractile dysfunction we chose an anesthetized open chest preparation in sheep. We occluded the diagonal coronary artery for 15 minutes and reperfused for 90 minutes. Hemodynamic parameters and wall thickening were monit ored. Unloading with the 60-ml Medos(R) HIA-VAD(R) was performed eithe r during ischemia (group II) or during reperfusion (group III). The re covery of nonuniformity indicated by post-ejection wall thickening was significantly faster (p<0.05) in both groups if compared to the non-a ssisted group (group I) (all groups n=4). Recovery of systolic wall th ickening in the postischemic region in group I was only 76+/-12%, whil e it was 103+/-11% and 92+/-11% in groups II and III, respectively (p< 0.05). In a canine model of global left Ventricular failure, we occlud ed the left anterior descending coronary artery for 20 min, and after 5 minutes of reperfusion, the circumflex artery for 45 min (group I, n =5). After 5 min of CX occlusion in group II we performed assisted cir culation for 90 min with the 10-ml (n=5) and the 25-ml (n=5) Medos(R) HIA-VAD(R). In group I, no dog survided, in group II, all survided 4 h ours of reperfusion (n=10). Lactate at the end of the experiment was 1 .1 +/- 0.9 mmol/L (10-ml) and 1.1 +/- 0.2 mmol/L (25-ml) (p>0.05 vs. b ase line). We conclude that the Medos(R) HIA-VAD(R) is a reliable assi st device that enhances myocardial recovery and allows sufficient peri pheral circulation in the case of cardiogenic shock.