PRESSURE WAVE-PROPAGATION AND INPUT IMPEDANCE IN THORACIC AORTA OF CONSCIOUS NEWBORN SHEEP

被引:6
作者
ADAMSON, SL [1 ]
WHITELEY, KJ [1 ]
LANGILLE, BL [1 ]
机构
[1] TORONTO HOSP, RES INST, TORONTO, ON M5G 1X5, CANADA
来源
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY | 1995年 / 268卷 / 02期
关键词
LAMB; WAVE VELOCITY; HEMODYNAMICS; WAVE REFLECTIONS; NOREPINEPHRINE; FEEDING; ANGIOTENSIN II; NITROPRUSSIDE; BIRTH; IMPEDANCE;
D O I
10.1152/ajpheart.1995.268.2.H558
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Aortic hemodynamics were examined in eight conscious newborn sheep. Flow and pressure in the thoracic aorta and pressure in the distal abdominal aorta were measured under control conditions and during pressure changes caused by bottle feeding or during intravenous infusions of nitroprusside, norepinephrine, or angiotensin II. Vasoconstriction affected aortic impedance, pressure wave amplification, and wave velocity similarly whether induced by feeding or by drugs. Central hemodynamics in the lamb were surprisingly similar to hemodynamics in the sheep fetus despite major changes in cardiovascular function at birth, largely because pressure-related increases in pulse wave velocity postpartum compensated for increased arterial lengths and increased heart rate. Wave reflection effects on pressure-flow relations were more prominent during vasoconstriction and less prominent during nitroprusside. Wave reflections in both lambs and fetal sheep return to the heart in early diastole; therefore, they do not add to ventricular afterload. Early diastolic return of reflected waves characterizes adults of many species, and demonstration of the phenomenon throughout the perinatal period reinforces arguments for its adaptive value.
引用
收藏
页码:H558 / H568
页数:11
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