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Left ventricular endocardial activation during right ventricular pacing: effect of underlying heart disease
Insights
Myocardial infarction significantly alters left ventricular (LV) activation patterns during right ventricular pacing. Anteroseptal infarction leads to earlier LV breakthrough and prolonged total activation times, suggesting altered conduction pathways.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Anatomy
Background:
- Right ventricular pacing is a common clinical procedure.
- Myocardial infarction (MI) can affect cardiac electrical activity.
- Understanding activation patterns post-MI is crucial for managing cardiac arrhythmias.
Purpose of the Study:
- To investigate the impact of myocardial infarction location on left ventricular endocardial activation during right ventricular pacing.
- To determine if infarction influences the earliest and latest sites of activation and total activation time.
Main Methods:
- Endocardial catheter mapping of the left ventricle in 40 patients.
- Patients were divided into three groups: no infarction (Group I), inferior infarction (Group II), and anteroseptal infarction (Group III).
- Analysis of earliest and latest activation times and total activation duration during right ventricular pacing.
Main Results:
- Left ventricular breakthrough was predominantly septal in all groups.
- Group III (anteroseptal MI) showed significantly earlier earliest LV activation (40 ms) compared to Group I (55 ms) and Group II (60 ms).
- Total endocardial activation time was significantly longer in Group III (118 ms) than in Group I (76 ms) and Group II (72 ms).
Conclusions:
- The site of previous myocardial infarction influences left ventricular endocardial activation patterns and conduction times.
- Prolonged total activation in anteroseptal MI suggests a crucial role for specialized conduction tissue in septal and anterior walls during RV pacing.
- These findings have implications for understanding electrical propagation in infarcted hearts.
Abstract:
Endocardial catheter mapping of the left ventricle was performed in 40 patients during right ventricular pacing to determine the effect of underlying myocardial infarction on endocardial activation. Group I comprised 18 patients without infarction, Group II 12 patients with inferior infarction and Group III 10 patients with anteroseptal infarction. Thirty-nine of the 40 patients had only a single left ventricular breakthrough site located on the midseptum in 33 cases, apical septum in 4 cases and basal septum in 2 cases. The earliest left ventricular local activation time during right ventricular pacing was earlier in Group III (40 +/- 11 ms) than in Group I (55 +/- 17 ms) and Group II (60 +/- 15 ms) (p less than 0.01). Total endocardial activation time was significantly longer in Group III (118 +/- 30 ms) than in Group I (76 +/- 14 ms) and Group II (72 +/- 20 ms) (p less than 0.001). The latest left ventricular site of activation during right ventricular pacing was the inferoposterior base in 14 (77%) of the 18 Group I patients, and 10 (83%) of the 12 Group II patients. The latest site of activation in Group III patients was variable. It is concluded that: left ventricular endocardial activation patterns and conduction times are influenced by the site of previous infarction. Longer total endocardial activation in Group III suggests that specialized conducting tissue in the septal and anterior walls may play an important role in left ventricular activation during right ventricular pacing.(ABSTRACT TRUNCATED AT 250 WORDS)