Left bundle branch block historical perspective
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; J. Adrian Gutierrez [2]
The history of bundle branch block research illustrates the evolving understanding of cardiac electrophysiology. As early as 1909, researchers Eppinger and Rothberger were conducting experiments in dogs in which they injected silver nitrate to destroy portions of the myocardium and induce electrocardiographic changes. These studies provided some of the earliest evidence of the importance of the cardiac conduction system. They observed that extensive destruction of the ventricular free wall produced relatively little change on the ECG, whereas small lesions in the interventricular septum resulted in significant electrocardiographic abnormalities due to injury of the bundle branches [1]
In 1910, Eppinger and Stoerk described patients with bundle branch block who exhibited a positive QRS complex in lead I and negative complexes in leads II and III. Based on extrapolation from canine experiments, they interpreted this pattern as right bundle branch block. Similar conclusions were later supported by Lewis, who published what is now recognized as one of the earliest electrocardiograms of left bundle branch block but also misclassified it as right bundle branch block. These interpretations remained widely accepted until human mapping studies by Barker and colleagues in 1929 demonstrated that the pattern actually represented left bundle branch block. [1]
In 1979, Schneider and colleagues analyzed newly acquired LBBB in the Framingham Heart Study. They found that LBBB was commonly associated with hypertension, cardiomegaly, coronary heart disease, and heart failure, with only 11% of affected individuals remaining free of cardiovascular abnormalities during follow-up. These findings helped establish LBBB as a marker of underlying cardiovascular disease and adverse prognosis rather than a benign electrocardiographic finding. [2]
References
- ↑ 1.0 1.1 Flowers NC (March 1987). "Left bundle branch block: a continuously evolving concept". J Am Coll Cardiol. 9 (3): 684–97. doi:10.1016/s0735-1097(87)80065-7. PMID 2950157.
- ↑ Schneider JF, Thomas HE, Kreger BE, McNamara PM, Kannel WB (March 1979). "Newly acquired left bundle-branch block: the Framingham study". Ann Intern Med. 90 (3): 303–10. doi:10.7326/0003-4819-90-3-303. PMID 154870.