Extravascular water content of heart and lungs after acute myocardial ischemia

The authors measured the extravascular water content of hearts and lungs of anesthetized dogs subjected to one of the following protocols: sham operation, circumflex artery ligation, increased left atrial pressure (Pla) or increased Pla and circumflex artery ligation. After 4 hr, extravascular water of the heart and lungs increased significantly in the three experimental groups when compared with values from sham-operated dogs. After circumflex artery ligation, extravascular heart water increased 29% and lung water 8%, although Pla and calculated pulmonary microvascular pressure (Pmv) did not change. Extravascular heart water also rose 30% after increasing Pla from 23 to 37 cmH₂O by inflating a left atrial balloon. In these dogs, extravascular lung water increased as a hyperbolic function of Pmv. Increasing Pla to 20 cmH₂O in dogs with coronary artery ligation resulted in a 16% increase in heart water. Also, at each Pmv, extravascular lung water was greater in dogs with coronary artery ligation than in dogs without. These data indicate that the increased extravascular lung water after coronary artery ligation cannot be explained solely by hemodynamic mechanisms. It is suggested that acute myocardial ischemia contributes to an increase in vascular permeability in the heart and lungs.