Mechanism of blood pressure elevation during angiotensin infusion |
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Authors: | OLAV STOKLAND,J
RGEN THORVALDSON,ARNFINN ILEBEKK,FREDRIK KIIL |
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Affiliation: | OLAV STOKLAND,JØRGEN THORVALDSON,ARNFINN ILEBEKK,FREDRIK KIIL |
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Abstract: | The mechanism of increased preload and its contribution to the rise in blood pressure during intravenous angiotensin infusion were studied in anesthetized dogs. In open-chest dogs angiotensin increased mean aortic blood pressure by 58±12 mmHg. Left ventricular end-diastolic dimension, measured as myocardial chord length (MCL) by ultrasonic technique, increased by 7±1 %. By inflating a balloon in the inferior vena cava, end-diastolic MCL was reduced to control value and the rise in mean aortic blood pressure was almost halved to 32±10 mmHg above control value. A similar preload effect was recorded in closed-chest dogs using end-diastolic left ventricular pressure as an estimate of left ventricular volume. During angiotensin infusion to the upper body only, end-diastolic MCL did not increase. When redistribution of the splanchnic blood volume was prevented, the effect of angiotensin on end-diastolic MCL was reduced to 1/3. Angiotensin reduced liver but not splenic dimension measured by ultrasonic technique. We conclude that about half of the rise in blood pressure during angiotensin infusion is due to increased end-diastolic volume caused by blood redistribution. About 2/3 of this increase in preload is due to redistribution from the splanchnic bed, mainly from the liver. |
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Keywords: | Aortic blood pressure blood redistribution dog left ventricular dimension liver dimension preload splanchnic blood volume splenic dimension ultrasonic measurements |
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