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Pathologic correlations in three cases of bilateral bundle branch disease with unusual electrophysiologic
Insights
This study correlates electrophysiologic findings with pathologic examination of the conduction system in patients with bifascicular block. It reveals sclerodegenerative disease as the anatomic basis for complex conduction abnormalities.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Pathology
Background:
- Bifascicular block presents diagnostic challenges.
- Electrophysiologic studies are crucial for understanding intraventricular conduction disease.
- Pathologic correlation is essential for elucidating the mechanisms of conduction abnormalities.
Observation:
- Three patients with bifascicular block underwent electrophysiologic studies and detailed conduction system examination.
- Patients exhibited prolonged H-V intervals and sclerodegenerative involvement of both bundle branches.
- Specific findings included alternating bundle branch block, sinus nodal reentrance, and left axis deviation.
Findings:
- Excellent correlation was found between electrophysiologic and pathologic findings.
- Sclerodegenerative disease provides an anatomic basis for observed conduction abnormalities.
- Amyloid infiltration and specific bundle branch involvement were identified as key pathological features.
Implications:
- This study clarifies the anatomic underpinnings of complex intraventricular conduction disease.
- Understanding these correlations aids in diagnosing and managing patients with heart block.
- The findings offer insights into the mechanisms of sinus nodal reentrance and left axis deviation.
Abstract:
Examination of the conduction system in three patients with bifascicular block who had electrophysiologic studies forms the basis for this report. Patients 1 and 2 had left bundle branch block and Patient 3 right bundle branch block and left axis deviation. The H-V interval was prolonged in each case (70, 65 and 60 msec, respectively). Serial section examination of the conduction system revealed sclerodegenerative involvement of both bundle branches in all cases. In Case 1, atrial extrastimulus testing converted left to right bundle branch block; in Case 2, it delineated a sinus echo zone with repetitive sinus nodal reentrance. In the latter case serial section revealed extensive amyloid infiltration of the approaches to the sinoatrial (S-A) node and the atrial preferential pathways. In Case 3, with right bundle branch block and left axis deviation, serial section revealed greater involvement of the anterior part of the main left bundle branch than of the posterior portion as well as involvement of the second part of the right bundle branch. The study revealed excellent correlation between electrophysiologic and pathologic findings in three cases of intraventricular conduction disease and demonstrated an anatomic basis for the electrophysiologic findings resembling alternating bilateral bundle branch block. Sinus nodal reentrance may be related to disease in the approaches to the S-A node thereby causing delay in perinodal tissue allowing sinus reentrance. Finally in Case 3, the anatomic substrate for left axis deviation may lie in a greater involvement of the anterior portion than of the posterior portion of the main left bundle rather than in the corresponding portions of the periphery.