Key result
Discrete punctate electrocautery lesions produced QRS changes in 65.6% of instances involving the branching portion of the common bundle, compared to 0% in the nonbranching portion.
Why the study?
Do discrete punctate electrocautery lesions in different portions of the canine bundle of His alter ventricular excitation and QRS complex morphology?
Do discrete punctate electrocautery lesions in different portions of the canine bundle of His alter ventricular excitation and QRS complex morphology?
Absolute Event Rate: 65.6% vs 0%
This preclinical study demonstrates that functionally distinct longitudinal fascicles exist only within the distal (branching) portion of the canine bundle of His, as evidenced by QRS morphology changes upon lesioning.
Hypothesis-generating for fascicular organization in canine His bundle; leaves open human relevance and requires clinical validation.
The alterations in ventricular excitation resulting from production of discrete punctate electrocautery lesions in the canine bundle of His were studied. Electrocardiographic changes were correlated with lesions identified anatomically by microscopic examination of the atrioventricular bundle. Although partial or complete atrioventricular block developed from lesions at several levels of the atrioventricular bundle, changes in the form of the QRS complex appeared only when lesions involved the distal portion of the bundle. Such QRS changes were recorded in 21 of 32 instances when the lesion involved the branching portion of the common bundle but in none of 6 instances when the lesion involved only the nonbranching portion of the common bundle. This study, then, provides evidence for functionally distinct longitudinal fascicles only within the distal portion of the common bundle. The syncytial character of the terminal fascicular (Purkinje) network may minimize the electrocardiographic evidence for such functional specificity within the common bundle.
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Watt et al. (1972) studied Ventricular excitation alterations. Discrete punctate electrocautery lesions in the branching portion of the common bundle vs. Lesions in the nonbranching portion of the common bundle was evaluated on Changes in the form of the QRS complex. Discrete punctate electrocautery lesions produced QRS changes in 65.6% of instances involving the branching portion of the common bundle, compared to 0% in the nonbranching portion.
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