Biomaterial Database

Studies of the effects of hypothermia on regional myocardial blood flow and metabolism during cardiopulmonary bypass. IV. Topical atrial hypothermia in normothermic beating hearts. 1977

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

This study compares (1) the effects of slowing heart rate by topical hypothermia in hearts perfused at 37 degrees C. with bradycardia produced by perfusion hypothermia (28 degrees C.) and (2) the consequences of counteracting the bardycardic effects of perfusion hypothermia by atrial pacing. Topical atrial hypothermia (myocardial temperature 37 degrees C.) produced a level of bradycardia comparable to perfusion hypothermia (82 vs. 71 beats per minute), but reduced myocardial oxygen requirements 25 per cent more than perfusion with 28 degrees C. blood. Myocardial oxygen uptake per beat did not change with topical atrial hypothermia but increased 40 per cent with perfusion hypothermia. Counteracting the bradycardic effects of perfusion hypothermia with atrial pacing (to 130 beats per minute) reduced subendocardial flow 25 per cent, caused a redistribution of flow away from the subendocardium, and produced evidence of ischemia on the intracavitary electrocardiogram. This study shows that (1) topical atrial hypothermia with systemic normothermia reduced myocardial oxygen demands as effectively as perfusion hypothermia and (2) subendocardial ischemia develops in beating empty hearts when the expected bradycardia of hypothermia does not occur.

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
D007511	Ischemia	A hypoperfusion of the BLOOD through an organ or tissue caused by a PATHOLOGIC CONSTRICTION or obstruction of its BLOOD VESSELS, or an absence of BLOOD CIRCULATION.	Ischemias
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
D010138	Pacemaker, Artificial	A device designed to stimulate, by electric impulses, contraction of the heart muscles. It may be temporary (external) or permanent (internal or internal-external).	Cardiac Pacemaker, Artificial,Artificial Cardiac Pacemaker,Artificial Cardiac Pacemakers,Artificial Pacemaker,Artificial Pacemakers,Cardiac Pacemakers, Artificial,Pacemaker, Artificial Cardiac,Pacemakers, Artificial,Pacemakers, Artificial Cardiac
D001831	Body Temperature	The measure of the level of heat of a human or animal.	Organ Temperature,Body Temperatures,Organ Temperatures,Temperature, Body,Temperature, Organ,Temperatures, Body,Temperatures, Organ
D001919	Bradycardia	Cardiac arrhythmias that are characterized by excessively slow HEART RATE, usually below 50 beats per minute in human adults. They can be classified broadly into SINOATRIAL NODE dysfunction and ATRIOVENTRICULAR BLOCK.	Bradyarrhythmia,Bradyarrhythmias,Bradycardias
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
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