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CARDIAC SLOWING, NOT CARDIAC IRRITABILITY, THE MAJOR PROBLEM IN THE PREHOSPITAL PHASE OF MYOCARDIAL INFARCTION 1
Author(s) -
Stock Eric
Publication year - 1971
Publication title -
medical journal of australia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.904
H-Index - 131
eISSN - 1326-5377
pISSN - 0025-729X
DOI - 10.5694/j.1326-5377.1971.tb92525.x
Subject(s) - medicine , irritability , myocardial infarction , bradycardia , sinus bradycardia , coronary care unit , cardiology , electrocardiography , anesthesia , atropine , shock (circulatory) , defibrillation , heart rate , blood pressure , menopause
The purpose of the study is to determine whether bradyarrhythmias are more common in the early phase of acute myocardial infarction, and whether their early treatment would reduce mortality. Patients were seen at their homes or hospitals close to their homes. A diagnosis of infarction was made on the clinical history, electrocardiographic and serum enzyme changes. Arrhythmias were detected clinically and confirmed by electrocardiography. Atropine was given by the intravenous route for all bradyarrhythmias, and lignocaine for ventricular irritability in the absence of bradycardia. Of 75 patients with acute myocardial infarctions seen at an earlier phase than is common in coronary care units, 25 presented with bradyarrhythmias. Of these, 20 had sinus bradycardia. This incidence was significantly higher than seen in coronary care units. The relative incidence of bradyarrhythmias was greatest near the onset of infarction and gradually diminished as the time lapse between infarction and initial examination increased. Early administration of atropine corrected heart block in four of five patients, sinus bradycardia and accompanying ventricular premature beats in all these five patients, and hypotension or shock in 11 of 13 patients. Only 12 patients required lignocaine when first seen. In 34 of the remaining 63 cases lignocaine was probably contraindicated. There were no deaths within the first 12 hours of initial examination. From these results it is inferred that, whereas cardiac irritability is predominant on and after admission to the coronary care unit, cardiac slowing is the major problem in the earlier, prehospital phase. The routine administration of lignocaine before hospital admission is therefore likely to be hazardous. Cardiac slowing may be a major cause of prehospital deaths, and atropine administration may prevent such deaths.