Regional changes in hemodynamics and cardiac myocyte size in rats with aortocaval fistulas. 1. Developing and established hypertrophy.
The effects of a large arteriovenous fistula on left and right ventricular hemodynamics and cardiac myocyte size were examined in adult rats at 1 week and 1 month after surgery. Cardiac output, left ventricular function, and right ventricular function were evaluated before obtaining isolated myocytes for cell size measurements. Average heart weight increased 35% at 1 week and 86% at 1 month in rats with fistulas. In general, myocyte hypertrophy was due to a proportional increase in length and width (length/width ratio remained constant). This change was more evident in the large hearts from rats with 1-month fistulas. At both the 1-week and 1-month intervals, the hypertrophic response of right ventricular myocytes was slightly greater than that observed in the left ventricle or interventricular septum. Left ventricular systolic pressure and dP/dtmax were significantly reduced at 1 week but returned to normal after 1 month of overloading. Left ventricular end-diastolic pressure was increased approximately fivefold and twofold at 1 week and 1 month, respectively. Right ventricular systolic pressure and dP/dtmax were increased at both intervals examined. We conclude that severe volume overloading from a large aortocaval fistula in the rat is characterized by 1) depressed left ventricular function at 1 week followed by a large compensatory hypertrophy and near normal function at 1 month, 2) right ventricular pressure overload, and 3) changes in myocyte shape that resemble normal physiological growth.
Liu
Z
Z
Department of Anatomy, University of South Florida, Tampa 33612.
Hilbelink
D R
DR
Crockett
W B
WB
Gerdes
A M
AM
D000818:Animals; D001011:Aorta; D001164:Arteriovenous Fistula / Q000473:pathology / Q000503:physiopathology*; D006332:Cardiomegaly / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D006439:Hemodynamics; D009206:Myocardium / Q000473:pathology*; D051381:Rats; D011919:Rats, Inbred Strains; D014684:Venae Cavae