Experimental study of the effect of external counterpulsation on blood circulation in the lower extremities

A bidirectional ultrasonic Doppler flowmeter with direct single sideband se paration was used to measure blood flow in the femoral and dorsalis pedis a rteries of 18 normal volunteers. Changes in blood-flow velocity and volume during external counterpulsation (ECP) with various sustaining times (the t ime for maintaining pressure) for inflation were studied. The results showe d that bloodflow velocity in the femoral and dorsalis pedis arteries is inc reased significantly by ECP, but the change is not closely related to the d uration of inflation. For a short sustaining time, the net forward blood-fl ow volume in arteries increased remarkably, but at longer sustaining times it dropped back significantly to a value even lower than that before ECP. T he sustaining time for inflation to produce the maximum net forward flow vo lume (the optimal sustaining time of inflation) was found to be at one-quar ter to one-third of the cardiac cycle. In a second study, changes in the ca libre of the femoral artery and its collateral and anastomotic branches in the hind extremities in 5 dogs before and after ECP with an optimal sustain ing time of inflation were examined by femoral arteriography. The experimen ts showed that the patency of collateral and anastomotic branches of the fe moral artery was greater before than after ECP. The study suggests that ECP could be an effective treatment for improving the blood circulation in ext remities.