The effects of intra-aortic counterpulsation on cardiac performance and metabolism in shock associated with acute myocardial infarction

Abstract

A B S T R A C T The effect of intra-aortic counterpulsation (IACP, 22-94 hr) on hemodynamics and cardiac energetics was evaluated in 10 patients in shock after acute myocardial infarction. The data clearly indicate that IACP improves myocardial oxygenation, enhances peripheral perfusion, and probably improves myocardial contractility in the severely diseased heart.Before treatment, decreases in cardiac index (mean value, 1.22 liter/min per m'), systolic ejection rate (67 ml/sec), and time-tension index per minute (1280 mm Hg -sec/min) were observed. Systemic vascular resistance varied widely. Low coronary blood flow (68 ml/min per 100 g) was associated with increased myocardial oxygen extraction (79%), low coronary sinus oxygen tension (20 mm Hg), and abnormal myocardial lactate-pyruvate metabolism.During 4-6 hr of IACP, systolic pressure and left ventricular outflow resistance decreased by 18% and 24%, respectively, while cardiac index improved by 38%. Diastolic arterial pressure rose 98%. Increase in coronary blood flow from an average of 68 to 91 ml/100 g per min (P < 0.001) was significantly correlated with rise in mean arterial pressure (r = 0.685). This correlation was best expressed in a third-order curve, which intercepts the point of no flow at a mean aortic pressure of 30 mm Hg. The flow-pressure curve is relatively flat above 65-70 mm Hg, but becomes steeper as mean aortic pressure falls below this point. Myocardial oxygen consumption remained essentially unchanged during early IACP and tended to rise during the later stages.However, the relationship of cardiac work performed to oxygen availability was markedly improved. Myocardial

Intraaortic Balloon Pumping for Ventricular Septal Defect or Mitral Regurgitation Complicating Acute Myocardial Infarction

“…In all patients, acute myocardial infarction was documented by a typical history, diagnostic electrocardiographic changes, and serum enzyme studies. Five patients had ventricular septal defect (VSD) [1][2][3][4][5][6][7][8][9] days after acute infarction. In two cases the infarction was anterior and in three inferior.…”

“…4 In contrast, counterpulsation can decrease ischemia by raising coronary perfusion pressure and will reduce afterload. [5][6][7][8][9][10][11][12] This report summarizes our experience in attempting to stabilize critically ill patients with these mechanical complications utilizing the intraaortic balloon pump (IABP).…”

Effect of intra‐aortic balloon pumping on left ventricular function: Evaluation by radionuclide ventriculography

“…The beneficial effects of intra-aortic balloon pumping in relieving symptoms in patients with angina has been postulated to be due to an increase in coronary blood flow (due to diastolic pressure augmentation) and also due to decrease in myocardial oxygen demand (due to decreases in afterload and preload) (Gewirtz et al, 1982;Kerber et al, 1976;Sasayoma et al., 1982), and in fact, an increase in coronary blood flow has only been found in patients with cardiogenic shock (Mueller et al, 1971).…”

Effect of Intraaortic Balloon Pumping on Left Ventricular Function in Patients With Persistent ST Segment Elevation After Revascularization for Acute Myocardial Infarction.

“…24 First, IABP augments diastolic arterial pressure, which is an important determinant of the coronary driving pressure. We have previously demonstrated that IABP increases peak coronary blood flow velocity in patients after coronary angioplasty for anterior AMI.…”