NONINVASIVE STUDY OF LEFT-VENTRICULAR FUNCTION AND SYSTEMIC HEMODYNAMICS DURING DIPYRIDAMOLE-ECHOCARDIOGRAPHY STRESS TEST

Left ventricular function and systemic haemodynamics were noninvasivel y assessed during cardiac stress testing with dipyridamole (0.84 mg kg (-1) i.v.) in 10 subjects (44-61 years) with normal coronary arteries (group 1), and in 14 patients (46-77 years) with coronary artery disea se either without (group 2, n=6) or with (group 3, n=8) echocardiograp hic evidence for myocardial ischaemia during test. Left ventricular wa ll motion and dimensions, and aortic root pressure and flow were obtai ned by Doppler echocardiography combined with an externally traced sub clavian artery pulse calibrated with brachial artery pressures. Periph eral arterial resistance, total arterial compliance, and aortic charac teristic impedance were estimated from aortic root pressure and flow, by use of a three-element windkessel model of the systemic circulation . Left ventricular ejection fraction improved from baseline to peak st ress in group 1 (mean+/-SD: 62+/-6% vs. 65+/-6%, P=0.05), whereas it w as not significantly changed in group 2 (58+/-10% vs. 56+/-6%) and dec reased in group 3 (53+/-10% vs. 43+/-10%, P<0.05). Otherwise, the haem odynamic response was similar in the three groups: heart rate and card iac index increased by at least 30% and 37%, respectively, whereas str oke index and arterial pressures were maintained at or slightly above baseline. Peripheral resistance decreased by at least 22%, and total a rterial compliance and aortic characteristic impedance were not signif icantly altered during test. The worsening of wall motion abnormality at peak stress in group 3 was not significantly related to the change in systemic haemodynamics. Thus, dipyridamole acted predominantly on t he arterioles without significantly influencing the large systemic art eries. Myocardial ischaemia during test impaired regional and global l eft ventricular function, but did not influence the systemic haemodyna mic response.