Hemodynamic effects of balloon obstruction of the abdominal aorta and superior vena caval-distal aortic shunting in dogs with myocardial infarction and shock

Abstract

The hemodynamic effects of extracorporeal circulatory support were investigated in closed chest dogs with myocardial infarction with shock produced by coronary embolization. Determinations of cardiac output, coronary perfusion (central aortic) pressure, systemic vascular resistance, left ventricular work, right atrial and left ventricular pressures were performed in the control state, following coronary embolization prior to extracorporeal circulatory support and following coronary embolization during two to four hours of extracorporeal circulatory support. Although there was diminution in cardiac output following coronary embolization, systemic vascular resistance did not rise appreciably and hence there was considerable arterial hypotension. Pumping of large volumes of blood from the venae cavae into the abdominal aorta did not produce a rise in central aortic pressure and increase of coronary perfusion. To increase coronary perfusion pressure with the aid of extracorporeal circulation it was necessary to increase systemic vascular resistance. This was achieved by obstruction of the abdominal aorta with a balloon catheter introduced via a femoral artery, the distal aorta below the site of obstruction being supplied with blood pumped from the superior vena cava. This method of mechanically increasing systemic vascular resistance required a small priming volume and relatively simple peripheral cannulations. A sustained rise in coronary perfusion (central aortic) pressure was produced which was unassociated with significant increases in right atrial or left ventricular diastolic pressures or in calculated left ventricular work.