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His-bundle electrogram in the convalescent stage of inferior myocardial infarction complicated with complete A-V
Insights
Patients with inferior wall myocardial infarction and complete atrioventricular block show prolonged His-ventricular (HV) intervals. This suggests a high frequency of intra-His block in these patients post-heart attack.
Area of Science:
- Cardiology
- Electrophysiology
- Internal Medicine
Background:
- Inferior wall myocardial infarction (MI) can present with conduction abnormalities.
- Complete atrioventricular (AV) block is a serious complication of acute MI.
Purpose of the Study:
- To investigate the electrophysiological characteristics of patients with a history of complete AV block following inferior wall MI.
- To assess for evidence of intra-His block in the convalescent stage.
Main Methods:
- His-bundle electrogram recordings were performed in the convalescent stage (average 6 months post-MI).
- AH and HV intervals were measured and compared to a control group.
- Patients with QRS width within normal limits and PR interval < 200 msec were included.
Main Results:
- The HV interval was significantly prolonged in patients (54 +/- 12 msec) compared to controls (42 +/- 9 msec, p < 0.02).
- Five patients exhibited HV intervals >= 60 msec.
- No split His (H) activity was observed, and AH intervals were normal (74 +/- 18 msec).
Conclusions:
- A high frequency of intra-His block is suggested in patients who experienced complete AV block during acute inferior wall MI.
- Prolonged HV intervals may indicate underlying conduction system disease beyond the acute phase.
Abstract:
Twelve patients with inferior wall myocardial infarction complicated with complete atrioventricular block during the acute stage were studied. The His-bundle electrogram was studied in the convalescent stage at an average of 6 months after the acute attack. The age of the patients was 62 +/- 16 years. The width of the QRS complex was within the normal range and the PR interval was less than 200 msec. AH time was 74 +/- 18 msec (mean +/- SD). No split H activity was observed. HV time however, was significantly prolonged in the 12 patients; 54 +/- 12 msec vs. 42 +/- 9 msec in the control group (p less than 0.02). Five patients had HV time equal to or more than 60 msec. Intra-His block was suggested to exist in a high frequency in the patients who had previous complete AV block during the acute stage of myocardial infarction of the inferior wall.