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Unusual electrocardiographic pattern during transvenous pacing from the middle cardiac vein
Insights
Permanent pacing from the middle cardiac vein typically causes a right bundle branch block. This case report details an unusual left bundle branch block pattern, highlighting potential diagnostic challenges with electrocardiogram interpretation.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Pacing
Background:
- Ventricular pacing is commonly achieved via the right ventricular apex.
- Pacing from the coronary sinus, specifically the middle cardiac vein, is an alternative approach.
- Previous reports indicate a right bundle branch block pattern for middle cardiac vein pacing.
Observation:
- This report documents an unusual left bundle branch block pattern during permanent ventricular pacing from the middle cardiac vein.
- This contrasts with the predominantly observed right bundle branch block pattern in prior studies.
- A high posterior infarct was noted, potentially influencing ventricular activation sequence.
Findings:
- The study identified a left bundle branch block pattern of ventricular depolarization during middle cardiac vein pacing.
- This finding deviates from the expected right bundle branch block pattern associated with this pacing site.
- Early right ventricular activation, possibly due to myocardial infarction, may explain the observed pattern.
Implications:
- Relying solely on electrocardiogram patterns can misdirect diagnosis, particularly regarding lead placement.
- Understanding atypical ventricular activation patterns is crucial for accurate interpretation of pacing electrocardiograms.
- This case emphasizes the need for comprehensive assessment beyond surface electrocardiogram findings in cardiac pacing.
Abstract:
This report documents the unusual occurrence of a left bundle branch block pattern of ventricular depolarization during permanent pacing from the middle cardiac vein. All previous reports of ventricular pacing from the middle cardiac vein have described a right bundle branch block pattern of ventricular activation (dominant R-waves in the right precordial leads), except in one case where both right and left bundle branch block patterns occurred at separate times. A high posterior infarct allowed early activation of the right ventricle from the middle cardiac vein. Undue reliance on the electrocardiogram may detract from the diagnosis of electrode malposition.