Pronounced reduction of aortic flow velocity and acceleration during heavy isometric exercise in coronary artery disease

Doppler-derived parameters of aortic flow were examined during heavy isometric exercise in 48 men with coronary artery disease (CAD) and in 48 gender- and age-matched healthy controls. The aim was to determine which parameters best separated the groups and to look for a possible relation between exercise-induced Doppler patterns and the extent of CAD. Isometric exercise was performed with a 2-hand bar dynamometer, and the subjects were required to perform 50% of maximal voluntary contraction for 2 minutes. Examination was performed with a pulsed Doppler transducer positioned at the suprasternal notch. Resting peak flow velocity, acceleration time, stroke volume index and cardiac index did not show significant differences between the groups. However, mean acceleration and stroke work were significantly lower in patients with CAD. In this group, exercise peak flow velocity decreased from 98 ± 13 to 55 ± 12 cm/s, flow velocity integral from 14 ± 3 to 7 ± 3 cm, mean acceleration from 11 ± 0.9 to 4.7 ± 1 m/s/s, and stroke volume index from 41 ± 6 to 23 ± 4 ml/m² (p < 0.001 for all). Cardiac index decreased from 2.7 ± 0.4 to 2 ± 0.2 liters/ min/m² (p < 0.05). Acceleration time increased from 82 ± 6 to 116 ± 7 ms. In most of the indexes, the directional changes induced by isometric exercise were similar in patients with CAD and in normal control subjects. The differences compared with the rest values were significantly greater in the CAD group, and especially in patients presenting with 3-vessel disease. In conclusion, isometric exercise results in marked changes in aortic flow patterns both in normal subjects and in subjects with CAD. Exercise-induced changes in peak flow velocity and mean acceleration were found to best separate the groups, and the degree of reduction in their values was directly related to the extent of CAD.