Direct mechanical assistance of the right ventricle with the hemopump in a porcine model

In 6 pigs, a 14F Hemopump was placed through the pulmonary artery into the right ventricle. The pulmonary artery was banded proximal to the outflow port of the Hemopump, and tightening the band increased right ventricular peak systolic pressure by 50%. There were significant falls in right ventricular stroke volume (from 43 ± 7.3 mL [± the standard deviation] to 27 ± 8.0 mL; p < 0.001) and cardiac output (from 4.94 ± 0.76 L/min to 3.70 ± 0.95 L/min; p < 0.01) and increases in right ventricular peak systolic pressure (from 28 ± 9.7 mm Hg to 42 ± 17.1 mm Hg; p < 0.01) and end-diastolic pressure (from 2 ± 0.8 mm Hg to 12 ± 6.4 mm Hg; p < 0.02). Mean aortic pressure fell (from 65 ± 29.9 mm Hg to 61 ± 9.6 mm Hg; p < 0.01), but systemic vascular resistance was unchanged, thus indicating a fall in left ventricular output reflected by a decrease in mixed venous oxygen saturation (from 60% ± 8.9% to 47% ± 7.6%; p < 0.01). After 15 minutes with the Hemopump at maximum speed, these variables returned to control levels (stroke volume, 38 ± 4.5 mL; cardiac output, 4.50 ± 0.63 L/min; right ventricular peak systolic pressure, 29 ± 8.3 mm Hg; right ventricular end-diastolic pressure, 4 ± 2.0 mm Hg; mean aortic pressure, 72 ± 10.4 mm Hg; mixed venous oxygen saturation, 56% ± 4.6% [all, p = not significant versus controls]). The Hemopump restored right ventricular perfusion pressure (64 ± 10.0 mm Hg to 41 ± 8.8 mm Hg with banding [ p < 0.001] to 56 ± 6.2 mm Hg with the Hemopump [ p = not significant versus control]) and pressure-rate product (3,199 ± 1,252 mm Hg · min to 5,962 ± 2,796 mm Hg · min with banding [ p < 0.01] to 3,368 ± 767 mm Hg · min with the Hemopump [ p = not significant versus control]). With acute partial pulmonary artery obstruction, a right ventricular Hemopump restores right ventricular output, reverses associated changes in left ventricular output, and offloads the right ventricle.