Interaction Between Regional Myocardial Ischaemia and Left Ventricular Performance Under Halothane Anaesthesia *

Abstract

The effect of halothane on the performance of myocardium supplied by a narrowed coronary artery has been assessed in an attempt to examine the influence of halothane on hearts with non-occlusive coronary artery disease. The study was divided into two parts: first, the left anterior descending (LAD) coronary artery was constricted beyond its second diagonal branch and, second, the left circumflex (LC) was constricted close to its origin In both parts, the myocardium was exposed to stepwise increases in inspired halothane before and after critical constriction of the vessel under study. Deepening halothane anaesthesia led to a dose-dependent depression of regional and global myocardial performance before critical constriction. After constriction, ischaemic changes in the contraction pattern of myocardium with a limited blood supply were noted If the ischaemia was confined to a small area of the heart (LAD stenosis) there was no significant deterioration of global LV performance. However, widespread ishchaemia (LC stenosis) led to irreversible heart failure in four of the five animals studied.

Implications for Anaesthesia of New Concepts in Cardiovascular Diseases: Discussion Paper

“…Moreover, in the case of halothane, the greater depression of wall function in the compromised territory was accompanied by the development of abnormal patterns of wall function. These abnormal patterns were similar to those observed in acute myocardial ischaemia (Theroux et al 1976) and were seen when coronary blood flow was severely reduced because of the reduction in arterial pressure (Francis et al 1982). Thus, it appears that anaesthesia may, when myocardial depression occurs, cause severe depression and ischaemic changes in the compromised myocardium.…”

“…Recently, the effects of halothane , 1981, Francis et al 1982) and enflurane (Cutfield et al 1980) on global and regional cardiac function have been studied in dogs in which a coronary artery had been critically narrowed. With critical constriction, autoregulation of coronary blood flow is lost and there is no coronary flow reserve.…”

Anaesthesia for myocardial revascularisation

“…Experimental and clinical studies with different volatile agents have also proved inconclusive. Data from studies with halothane have suggested that it may be a useful volatile supplement for patients with ischaemic heart disease, although this is controversial [2,19]. The use of isoflurane has provoked considerable controversy.…”

“…Of the anaesthetic agents in common use halothane [2], enflurane [3]. fentanyl and its derivatives [4][5][6], nitrous oxide [7] and isoflurane [8] have all at some time been associated with either haemodynamic effects likely to promote myocardial oxygen imbalance, experimental evidence of ventricular wall motion abnormality, or direct metabolic or electrophysiological evidence of anaerobic cardiac metabolism.…”

Beta Blockade in Anaesthesia

“…Experimental studies using acute coronary occlusions have shown that halothane (55), enflurane (56) and morphine (57,58) minimize the signs of ischaemia and reduce the size of myocardial infarction after coronary occlusion (58,59). However, more recent studies using a model of critical constriction rather than occlusion of a coronary artery have shown that halothane and enflurane cause more depression of an area of the myocardium supplied by a narrowed coronary artery than of an area with a normal blood supply (60,61,62). In the case of halothane, abnormal patterns of wall function were observed and appeared to indicate that the compromised segment was becoming ischaernic (60, 61).…”