Coronary Hemodynamics during Hemopump Left-Intraventricular Assistance

Abstract

Hemopump left intraventricular pumping (HP) can permit percutaneous transluminal angioplasty (PTCA) in high-risk patients. Benefits may be related to left ventricular unloading or myocardial perfusion improvement, or both. Direct ultrasonic measurements of coronary blood flow were made in the dilated vessel after a successful PTCA in five patients. A 3 Fr intracoronary Doppler catheter was placed in the coronary artery to measure flow velocities (maximal or diastolic velocity; minimum or systolic velocity and mean velocity). A SwanGanz catheter was used to measure the cardiac index and pulmonary capillary wedge pressure. Mean aortic pressures were monitored through an 8 Fr guiding catheter. Measurements were made after a 5-min period of minimal speed (TO) of the HP to avoid retrograde regurgitation through the turbine; during the increase from minimum to maximal speed (T1); after a 5-min period of maximal HP flow (3l/min) (T2) and after HP was pulled back (T3). From TO to T2, cardiac index rose from 1.93 ± 0.38 to 3.26 ± 0.35 l/min/m² and capillary wedge pressure decreased from 18 ± 6 to 13 ± 5 mmHg (p < 0.05); from T2 to T3, cardiac index decreased to 2.4 ± 0.4 while capillary wedge pressure increased to 17 ± 5 (p < 0.05). Mean arterial pressure and heart rate did not change significantly throughout the study. When the hemopump flow was raised to high speed, coronary blood flow increased immediately but returned shortly to baseline values. At steady state, coronary blood flow was stable at values similar to baseline with a tendency for minimum velocity to be higher, suggesting an improvement in systolic myocardial perfusion. When the HP was removed, coronary blood flow dropped immediately. The coronary resistance index changed inversely to coronary blood flow. At high speed, resistance immediately decreased, returning in steady state to baseline values. When the HP was off, resistance increased immediately. Thus, this preliminary study suggests an improvement of myocardial perfusion during HP support. Further studies are needed to evaluate the effect of HP support on myocardial protection in humans.