EVALUATION OF A PULSATILE PEDIATRIC VENTRICULAR ASSIST DEVICE IN AN ACUTE RIGHT HEART-FAILURE MODEL

Background. The development of pulsatile ventricular assist devices fo r children has been limited mainly by size constraints. The purpose oi : this study was to evaluate the MEDOS trileaflet-valved, pulsatile, p ediatric right ventricular assist device (stroke volume = 9 mt) in a n eonatal lamb model of acute right ventricular failure. Methods. Right ventricular failure was induced in ten 3-week-old lambs (8.6 kg) by ri ght ventriculotomy and disruption of the tricuspid valve. Control grou p I (n = 5) had no mechanical support whereas experimental group 2 (n = 5) had right ventricular assist device support for 6 hours. The foll owing hemodynamic parameters were measured in all animals: heart rate and right atrial, pulmonary arterial, left atrial, and systemic arteri al pressures. Cardiac output was measured by an electromagnetic flow p robe placed on the pulmonary artery. Results. All results are expresse d as mean +/- standard deviation and analyzed by Student's t test. A p value less than 0.05 was considered statistically significant. Baseli ne measurements were not significantly different between groups and in cluded systemic arterial pressure, 80.6 +/- 12.7 men Hg; right atrial pressure, 4.6 +/- 1.6 nun Hg; mean pulmonary arterial pressure, 15.6 /- 4.2 mm Hg; left atrial pressure, 4.8 +/- 0.8 mw Mg; and cardiac out put, 1.4 +/- 0.2 L/min. Right ventricular injury produced hemodynamics compatible with right ventricular failure in both groups: mean system ic arterial pressure, 38.8 +/- 10.4 nm Hg; right atrial pressure, 16.8 +/- 2.3 man Hg; left atrial pressure, 1.4 +/- 0.5 nun Hg; and cardiac output, (0.6 +/- 0.1 L/min. All group 1 animals died at a mean of 71. 4 +/- 9.4 minutes after the operation. All group 2 animals survived th e duration of study. Hemodynamic parameters were recorded at 2, 4, and 6 hours on and off pump, and were significantly improved at all time points: mean systemic arterial pressure, 68.0 +/- 13.0 mm Hg; right at rial pressure, 8.2 +/- 2.3 mm Hg; left atrial pressure, 6.4 +/- 2.1 nu n Hg; and cardiac output, 1.0 +/- 0.2 L/min. Conclusions. The results demonstrate the successful creation of a right ventricular failure mod el and its salvage by a miniaturized, pulsatile fight ventricular assi st device. The small size of this device makes its use possible even i n small neonates. (C) 1997 by the Society of Thoracic Surgeons. .