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Histopathology of the conduction system in patients with atrioventricular or intraventricular conduction disturbances
Insights
Pre-existing chronic changes in the heart's conduction system, often age-related, predispose individuals to specific conduction disturbances during acute myocardial infarction (AMI). These chronic changes, not acute ones, are key factors.
Area of Science:
- Cardiology
- Pathology
- Electrophysiology
Background:
- Acute myocardial infarction (AMI) can cause conduction disturbances.
- The role of pre-existing conduction system changes in AMI outcomes is not fully understood.
Purpose of the Study:
- To investigate the relationship between pre-existing conduction system pathology and conduction disturbances during AMI.
Main Methods:
- Autopsy and histological examination of the conduction system in 9 fatal AMI cases.
- Comparison with a control series of violent deaths.
Main Results:
- Only one case showed acute changes in the conduction system.
- Chronic changes were prevalent and comparable to controls.
- Good correlation found between conduction disturbances and histopathological changes in most cases.
Conclusions:
- Age-related chronic changes in the conduction system, not acute changes, determine susceptibility to conduction disturbances during AMI.
- These chronic changes predispose individuals to specific conduction issues when acute ischemia occurs.
Abstract:
In 9 lethal cases where clinical signs gave rise to the suspicion of acute myocardial infarct (AMI) where well-characterized e.c.g.-changes, permanent or intermittent, were found by monitoring, a very careful autopsy of the heart was carried out, combined with a meticulous histological investigation of the conduction system. Acute changes of mild degree in the conduction system were found only in one case, possibly explaining the left bundle branch block found in this case. In the remaining cases, nothing but chronic changes were found and they did not exceed significantly the changes otherwise to be found in the agegroups concerned in a "control series" of violent deaths not preceded by symptoms of heart disease. According to an estimate there was good correlation between the conduction disturbances demonstrated and the localization of histopathological changes in seven of nine patients; in one of the latter correlation was relatively good; correlation was dubious only in one case. On this basis the authors conclude that present changes in the conduction system which are assumed mainly to be age-related, are the factors to determine the type of conduction disturbances from which the patient will suffer if acute heart ischaemia sets in, for instance due to an AMI, in fact, changes by which he will be predisposed to such disturbances.