Effects of Hemopump support on left ventricular unloading and coronary blood flow.

The effects of the Hemopump (HP) on left ventricular (LV) and coronary hemodynamics, with and without myocardial ischemia, were studied in an acute, anesthetized, open-chest dog preparation (n = 6). Coronary blood flow velocity in the left circumflex was assessed with an intracoronary Doppler catheter. Measurements were made at two pump speeds (minimal = HP1 and maximal = HP7) before coronary ligation (control), after ligation of the LAD (ischemia), and after induction of cardiac failure by multiple ligations of the diagonal branches (failure). Changing from HP1 to HP7 resulted in 1) Increased total cardiac output in ischemia and failure; 2) Increased mean aortic pressure and systemic vascular resistance in control, ischemia, and failure; 3) Decreased LV external work (LV systolic pressure X stroke volume) in control, ischemia, and failure; 4) Decreased LV end diastolic pressure in ischemia; 5) Decreased LV systolic pressure and pressure-rate product in failure; and 6) Increased coronary blood flow/O2 demand ratio in failure. Hemopump support reduced O2 demand by LV decompression, and improved blood flow/O2 demand ratio in the nonoccluded coronaries of ischemic, failing hearts.