[Effect of arterial hypoxia and acidosis on fibrillation threshold in the cat heart in vivo].

The influence of severe arterial hypoxia and acidosis on the fibrillation threshold was checked in 22 cats. Two groups were formed: in 10 cats (group I) acidosis was produced by 2-N lactic acid infusion; in the second group of 12 animals the respirator was turned off for 60 seconds, thus producing a low arterial PO2. If hypoxia and acidosis were severe enough, the fibrillation threshold was significantly lowered in either group. The pathophysiological mechanisms of these findings are discussed.