Influence of adenosine-induced hypotension on the canine myocardium rendered acutely ischaemic by artificial stenosis.
An open-chest preparation was carried out in 14 pentobarbitone anaesthetized dogs in order to evaluate the myocardial effects of controlled hypotension induced by adenosine in the presence of a severe coronary stenosis that caused ischaemia of the left anterior ventricular wall. Myocardial performance, blood flow and metabolism were studied before and during a 78 +/- 3% reduction of flow in the left anterior descending coronary artery (LAD) and during adenosine-induced hypotension (approximately 40% reduction of the mean arterial pressure) in the presence of the LAD stenosis. The LAD stenosis decreased the myocardial lactate uptake (P less than 0.01), increased ST-T segment depression (P less than 0.05) of the left ventricular subendocardial ECG, and reduced cardiac output by 10% (P less than 0.05). In the presence of stenosis, the mean arterial pressure was reduced by adenosine from 10.4 +/- 0.6 kPa to 6.3 +/- 0.2 kPa for 15 min. Heart rate decreased by 22% (P less than 0.01). There was no change in cardiac output during hypotension, while the rate-pressure product decreased by 47% (P less than 0.01) and myocardial oxygen consumption decreased by 30 +/- 7%. Adenosine increased the coronary sinus blood flow by 52% (P less than 0.01), while the LAD flow distal to the stenosis was not significantly reduced. Myocardial lactate uptake was not further reduced and subendocardial ECG signs of ischaemia were not aggravated by the hypotension. In conclusion, adenosine-induced hypotension did not aggravate the subendocardial ECG signs of acute poststenotic myocardial ischaemia. Nor did myocardial lactate determinations indicate aggravation of myocardial ischaemia.(ABSTRACT TRUNCATED AT 250 WORDS)
Owall
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Department of Anaesthesia, Karolinska Hospital, Stockholm, Sweden.
Rudehill
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Sylvén
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C
Sollevi
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A
D000241:Adenosine / Q000627:therapeutic use*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002302:Cardiac Output / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects; D003327:Coronary Disease / Q000188:drug therapy* / Q000503:physiopathology; D004285:Dogs; D007773:Lactates / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects
D007773:Lactates; D000241:Adenosine