Coronary Hemodynamics during Positive (+Gz) Acceleration.

摘要

Left circumflex (LC) and left anterior descending (LAD) coronary flows, coronary perfusion pressure (P sub ca), and arterial O2 content (CaO2) were determined in five dogs, lightly anesthetized with chloralose, during exposrues to +2.0 and +3.0 Gz stress; and for three of these dogs at +3.5 Gz. At +2.0 Gz, except for one dog with the most marked decrease in P sub ca LC and LAD flows increased above control by 15 s and thereafter gradually returned toward control; coronary resistances were significantly below control at 15 and 30 s )p < 0.05). At +3.0 Gz, LC and LAD flows were significantly greater than control (p < 0.05) from 30 to 60 s, while resistances were below control (p < 0.05). At +3.5 Gz, LC flow was maintained above control by a much reduced resistance, with P sub ca below control; LAD flow increased in one dog, remained unchanged in one, and decreaed slightly in one, although resistance always decreased. CaO2 did not change significantly at any +Gz level, and myocardial O2 transport paralleled the changes in coronary flow. (Author)