[Right ventricular assist for experimental acute right ventricular failure in dogs].
In order to assess the efficacy and the problems of right ventricular (RV) assist in supporting the failing RV, we analyzed the influence of RV assist on pulmonary circulation, respiratory function and left ventricular (LV) function in dogs. Thirty healthy mongrel dogs were anesthetized with thiopental sodium. The animals were intubated and ventilated with 100% oxygen. Tidal volume was 15 ml/kg at a rate of 20 per minute. RV failure was produced by ligation of the right coronary artery at its origin and the mid-portion. Tricuspid regurgitation was induced by tearing the chordae tendineae with a specially made knife, while 5M-NaOH was injected into the RV free wall. Then, RV support was initiated by placing a drainage cannula in the right atrium and a perfusion cannula in the pulmonary artery trunk. The RV assist was done with a diaphragm type pneumatic pump, which worked in ECG asynchronous mode (% systole:40%, 100 beats per minute). Animals were divided into three groups according to RV assist rate; Group I: 30% (n = 10), Group II: 60% (n = 10), Group III: 100% (n = 10). Hemodynamics were observed for five hours and measured once an hour. Hemodynamically, there were no significant differences in mean right atrial pressure, pulmonary artery pressure or aortic pressure at any time for the three groups. In terms of net infiltration pressure, given by the formula, pulmonary microvascular pressure minus colloid osmotic pressure, a significant difference appeared early, at the 1st hour, between Groups I and III (P < 0.01), and lasted until the 5th hour. Alveolar-arterial oxygen differences were highest in Group III and lowest in Group I throughout most of the experiment. Early on, at the 1st hour, a significant difference of Alveolar-arterial oxygen difference developed between Groups I and III (p < 0.01) and at the 2nd hour a significant difference was also seen between Groups II and III (p < 0.05). Extravascular lung water was 8.9 +/- 2.2 ml/kg at the 5th hour in Group III, which was significantly higher than that in Groups I and II (p < 0.01), which were 6.1 +/- 1.3 and 6.1 +/- 1.1 ml/kg. LV max. dp/dt at the 5th hour in Group III was significantly lower than that in Groups I and II (p < 0.05). Postmortem histopathologic examination showed a high degree of perivascular cuffing in Group III, slight cuffing in Group II, and almost none in Group I and the control group. There was no alveolar flooding in any group.(ABSTRACT TRUNCATED AT 400 WORDS)
Kimura
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Department of Surgery (Section 2), Sapporo Medical College & Hospital, Japan.
D000208:Acute Disease; D000818:Animals; D004285:Dogs; D006333:Heart Failure / Q000503:physiopathology* / Q000601:surgery; D006339:Heart Rate; D006353:Heart-Assist Devices; D006439:Hemodynamics; D011652:Pulmonary Circulation; D012119:Respiration; D016278:Ventricular Function, Right