Biomaterial Database

Studies of the effects of hypothermia on regional myocardial blood flow and metabolism during cardiopulmonary bypass. III. Effects of temperature, time, and perfusion pressure in fibrillating hearts. 1977

J R Brazier, and N Cooper, and D H McConnell, and G D Buckberg

This study compares the effects of normothermic and hypothermic spontaneous fibrillation at perfusion pressures of 100 and 50 mm. Hg on the adequacy and distribution of coronary blood flow. During normothermia (37 degrees C.), subendocardial oxygen delivery decreased 45 per cent ( p less than 0.01) and left ventricular flow became redistributed away from the subendocardium (endo-epi flow ratio fell from 1.2 to 0.8) when perfusion pressure was lowered to 50 mm. Hg; abnormal glycolysis (lactate washout) became evident when perfusion pressure was raised to 100 mm. Hg and ischemia was demonstrated by histochemical stains. Hypothermia (28 degrees C) reduced myocardial oxygen uptake 52 per cent (p less than 0.01) at 100 mm. Hg perfusion pressure; left ventricular flow, distribution, and metabolism did not change from control values. Lowering perfusion 50 mm Hg caused a pronounced reduction in subendocardial oxygen delivery (63 per cent, p less than 0.01); abnormal glycolysis developed and histochemical ischemia was seen. These studies show that lowering perfusion pressure in normothermic fibrillating hearts impairs oxygen delivery to the left ventricular subendocardium. While hypothermia significantly reduces left ventricular oxygen requirements, the ventricle is not protected against subendocardial ischemia if perfusion pressure falls to levels frequently used during clinical open-heart surgery.

UI	MeSH Term	Description	Entries
D007036	Hypothermia, Induced	Abnormally low BODY TEMPERATURE that is intentionally induced in warm-blooded animals by artificial means. In humans, mild or moderate hypothermia has been used to reduce tissue damages, particularly after cardiac or spinal cord injuries and during subsequent surgeries.	Induced Hypothermia,Mild Hypothermia, Induced,Moderate Hypothermia, Induced,Targeted Temperature Management,Therapeutic Hypothermia,Hypothermia, Therapeutic,Induced Mild Hypothermia,Induced Mild Hypothermias,Induced Moderate Hypothermia,Induced Moderate Hypothermias,Mild Hypothermias, Induced,Moderate Hypothermias, Induced,Targeted Temperature Managements
D007773	Lactates	Salts or esters of LACTIC ACID containing the general formula CH3CHOHCOOR.
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D010101	Oxygen Consumption	The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)	Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D010477	Perfusion	Treatment process involving the injection of fluid into an organ or tissue.	Perfusions
D011312	Pressure	A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Pressures
D002315	Cardiopulmonary Bypass	Diversion of the flow of blood from the entrance of the right atrium directly to the aorta (or femoral artery) via an oxygenator thus bypassing both the heart and lungs.	Heart-Lung Bypass,Bypass, Cardiopulmonary,Bypass, Heart-Lung,Bypasses, Cardiopulmonary,Bypasses, Heart-Lung,Cardiopulmonary Bypasses,Heart Lung Bypass,Heart-Lung Bypasses
D003187	Compliance	Distensibility measure of a chamber such as the lungs (LUNG COMPLIANCE) or bladder. Compliance is expressed as a change in volume per unit change in pressure.
D003326	Coronary Circulation	The circulation of blood through the CORONARY VESSELS of the HEART.	Circulation, Coronary
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog