EFFECTS OF FAILURE OF THE RIGHT SIDE OF THE HEART AND INCREASED PULMONARY RESISTANCE ON MECHANICAL CIRCULATORY SUPPORT WITH USE OF THE MINIATURIZED HIA-VAD DISPLACEMENT PUMP SYSTEM

This experimental study was designed to assess the influence of failur e of the right side of the heart or pulmonary hypertension, or both, o n the performance of a novel miniaturized left ventricular assist devi ce. In small-sized dogs (n = 50) ischemic global left ventricular fail ure was induced and support was provided by the HIA-VAD displacement p ump (stroke volume 10 or 25 ml) installed as a left ventricular assist device, In three groups of animals (n = 10 each) pulmonary hypertensi on was created before induction of global left ventricular failure. Du ring left ventricular assist device support temporary ischemic failure of the right side of the heart was induced in four groups of animals (n = 10 each). In the group subjected to left ventricular failure, sup port with the left ventricular assist device, and right ventricular fa ilure during left ventricular assist, left atrial pressure and cardiac index were significantly lower than in the group subjected to left ve ntricular failure and left ventricular assist alone (2 +/- 6 versus 11 +/- 6 mm Hg and 1.6 +/- 0.3 versus 1.0 +/- 0.4 L/(min/m(2)), respecti vely, p < 0.05). In the group subjected to pulmonary hypertension, lef t ventricular failure, and left ventricular support, left atrial press ure dropped to values near zero but cardiac index remained unaltered a s compared with results with the same regimen without pulmonary hypert ension. However, when right ventricular failure was added (that is, pu lmonary hypertension, left ventricular failure, left ventricular suppo rt, and right ventricular failure during support with the left ventric ular assist device) left atrial pressure dropped to negative values (p < 0.05) and cardiac index progressively deteriorated. When, in an add itional group of dogs, biventricular support was installed in the latt er regimen, circulation was initially well supported but oxygenation d eteriorated in 60% of eases. We conclude that (1) adequate right ventr icular function was indispensable during support with the left ventric ular assist device, (2) the combination of pulmonary hypertension and right ventricular failure led to the ''low left ventricular assist dev ice output syndrome,'' and (3) biventricular mechanical support in the presence of pulmonary hypertension may be complicated by the alveolar leakage syndrome.