DIRECT MECHANICAL ASSISTANCE OF THE RIGHT VENTRICLE WITH THE HEMOPUMPIN 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 fall s in right ventricular stroke volume (from 43 a 7.3 mL [+/- the standa rd 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 r ight ventricular peak systolic pressure (from 28 a 9.7 mm Hg to 42 +/- 17.1 mm Hg; p < 0.01) and end-diastolic pressure (from 2 +/- 0.8 mm H g 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 re sistance was unchanged, thus indicating a fall in left ventricular out put 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 Hemop ump at maximum speed, these variables returned to control levels (stro ke volume, 38 +/- 4.5 mL; cardiac output, 4.50 +/- 0.63 L/min; right v entricular 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% fall, p = no t significant versus controls]). The Hemopump restored right ventricul ar perfusion pressure (64 +/- 10.0 mm Hg to 41 +/- 8.8 mm Hg with band ing [p < 0.001] to 56 +/- 6.2 mm Hg with the Hemopump [p = not signifi cant 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 a 7 67 mm Hg min with the Hemopump [p = not significant versus control]). With acute partial pulmonary artery obstruction a right ventricular He mopump restores right ventricular output, reverses associated changes in left ventricular output, and offloads the right ventricle.