Key result
Stepwise reduction of pulmonary arterial blood flow from 100% to 0% during venoarterial bypass in awake goats decreased mean aortic pressure from 110 to 66 mmHg.
Stepwise reduction of pulmonary blood flow during venoarterial bypass in awake goats proportionally decreases systemic hemodynamics and diversely activates vasoactive humoral factors.
May lower aortic pressure during VA bypass with reduced pulmonary flow; leaves open translation to clinical ECMO hemodynamics.
The effects of reduced pulmonary arterial blood flow (PAF) during venoarterial bypass (VAB) on hemodynamic and humoral conditions were investigated in a series of experiments in a chronic animal model. A biventricular bypass system was installed in five adult goats weighing 49.8 +/- 1.1 kg. Two weeks later, the extracorporeal circuitry was changed to VAB without anesthesia. The PAF was reduced stepwise from 100% to 50, 25, 10, and 0% of total systemic flow. The mean aortic pressure and systemic vascular resistance decreased from 110 +/- 14 to 66 +/- 3 mmHg and from 1,288 +/- 77 to 740 +/- 73 dyne.sec/cm5, respectively, in proportion to the decrease in PAF from 100 to 0%. The prostaglandin E2 concentration increased from 1.5 +/- 0.6 to 8.8 +/- 0.6 pg/ml following the decrease in PAF from 100 to 0%. The renin-angiotensin system increased in proportion to the decrease in PAF. In contrast, the epinephrine and norepinephrine concentrations (60 +/- 10 and 227 +/- 80 pg/ml, respectively, at 100% PAF) did not change appreciably even at 10% PAF, but were markedly elevated to 335 +/- 117 and 2,088 +/- 1,503 pg/ml at 0% PAF. The antidiuretic hormone level similarly changed. In conclusion, decrease in PAF during VAB exerts significant effects on hemodynamics in a proportional manner and on vasoactive humoral factors in a diverse manner.
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Takewa et al. (1997) studied Venoarterial bypass (n=5). Stepwise reduction of pulmonary arterial blood flow vs. 100% pulmonary arterial blood flow was evaluated on Hemodynamic and humoral conditions. Stepwise reduction of pulmonary arterial blood flow from 100% to 0% during venoarterial bypass in awake goats decreased mean aortic pressure from 110 to 66 mmHg.
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