Haemodynamic Alterations During Ischaemia Induced by Dobutamine Stress Testing

To identify the haemodynamic response to ischaemia induced by dobutamine stress testing, 15 patients with a first acute myocardial infarction underwent right-sided heart catheterization during dobutamine stress cross-sectional echocardiography. Haemodynamic variables and echocardiography were recorded at rest and during dobutamine infusion at each dose from 5 to a maximum of 40 micrograms kg-1 min-1. Ischaemia was diagnosed by cross-sectional echocardiography if asynergy appeared in at least two ventricular segments other than the area of acute myocardial infarction. Ischaemia was absent in six patients (group I) and identified in nine (group II). Response curves for each haemodynamic variable in the two groups were compared by applying Zerbe's method. The response curves were similar in the two groups for heart rate, arterial, right atrial, pulmonary arterial and pulmonary artery wedge pressures. The response curves were significantly different in groups I and II for thermodilution cardiac output, stroke volume and systemic vascular resistance (P less than 0.05). An increase in stroke volume was observed at low dosage of dobutamine in both groups. From low to maximum dose, stroke volume remained unchanged in group I and was significantly decreased in group II. Ischaemia induced by dobutamine stress testing leads to a decrease in stroke volume with no change in pulmonary artery wedge pressure.