Left ventricular assistance using a catheter-mounted coaxial flow pump (Hemopump) in a canine model of regional myocardial ischaemia

The global and regional effects of left ventricular circulatoryassistance were examined in dogs during acute myocardial infarctionusing a new coaxial flow device (Hemopump). In 12 dogs the leftanterior descending coronary artery was occluded for 4 h andsubsequently reperfused for 12 h. In six dogs, left ventricularassistance was started 90 min after coronary artery occlusionand maintained for several hours; six control animals receivedno circulatory support. Survival rate in the animals receivingmechanical support was 100% vs 0% in the control group. TheHemopump reduced left ventricular stroke work up to 80% andmaintained blood flows to the brain, kidneys, liver and intestinethroughout the experiment. Infarct size, expressed as a percentageof the left ventricle, however, was not mod(fied (12% in supportedanimals vs 13% in control dogs). Side effects of the coaxialfiowpump were thrombocytopaenia, occurring in all six dogs, andhaemolysis, which was demonstrated in one animal. It was concludedthat the Hemopump provides effective global and regional circulatorysupport in a canine model of severe cardiogenic shock. However,the value of left ventricular support to modify infarct sizecould not be demonstrated in this experimental model.     

EFFECTS OF URAPIDIL, KETANSERIN AND SODIUM NITROPRUSSIDE ON VENOUS ADMIXTURE AND ARTERIAL OXYGENATION FOLLOWING CORONARY ARTERY BYPASS GRAFTING

Thirty patients who developed arterial hypertension followingcoronary artery bypass grafting, despite sedation, were treatedrandomly with sodium nitroprusside (SNP), ketanserin or urapidil.All drugs significantly decreased arterial pressure. Two patientswere withdrawn because hypertension failed to respond to ketanserin.Significant tachycardia was noted only in the SNP group. Anincrease in and significant decreases in systemic and pulmonaryvascular resistances were seen in all groups. Following administrationof SNP, (PA^o2–Pa^o2) and s/t increased significantly, whereasPa^o2 decreased significantly. Three patients were withdrawnfrom the SNP group because s/t was > 30%. (PA^o2—Pa^o2)and s/t showed no significant changes following the administrationof ketanserin or urapidil. These drugs may have advantages overSNP in the management of hypertension following coronary arterybypass surgery.