Sep 1, 1979

Second-degree atrioventricular block

Circulation
D P Zipes

Abstract

1) While it is possible only one type of second-degree AV block exists electrophysiologically, the available data do not justify such a conclusion and it would seem more appropriate to remain a "splitter," and advocate separation and definition of multiple mechanisms, than to be a "lumper," and embrace a unitary concept. 2) The clinical classification of type I and type II AV block, based on present scalar electrocardiographic criteria, for the most part accurately differentiates clinically important categories of patients. Such a classification is descriptive, but serves a useful function and should be preserved, taking into account the caveats mentioned above. The site of block generally determines the clinical course for the patient. For most examples of AV block, the type I and type II classification in present use is based on the site of block. Because block in the His-Purkinje system is preceded by small or nonmeasurable increments, it is called type II AV block; but the very fact that it is preceded by small increments is because it occurs in the His-Purkinje system. Similar logic can be applied to type I AV block in the AV node. Exceptions do occur. If the site of AV block cannot be distinguished with certainity from th...Continue Reading

Mentioned in this Paper

Structure of Purkinje Fibers
Heart Block
Left Bundle Branch of His
Atrioventricular Block
Electrophysiologic Follow-up Study With Pacing and Recording to Test Effectiveness of Therapy, Including Induction or Attempted Induction of Arrhythmia
Biologic Preservation
Structure of Atrioventricular Node
Electrophysiology (Science)
Cardiac Electrophysiologic Stimulation and Recording Study
Electrocardiographic Recorders

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