Determination of the site of impaired conduction in atrio-ventricular block
| Autor: | N. Ali, R.A. Massumi |
|---|---|
| Rok vydání: | 1970 |
| Předmět: |
Adult
Male Cardiac Catheterization Pacemaker Artificial medicine.medical_specialty Adolescent Heart block Bundle-Branch Block Electrocardiography Heart Conduction System Internal medicine Block (telecommunications) medicine Humans Atrial tachycardia Aged Atrial pacing business.industry Middle Aged medicine.disease Thermal conduction Bundle branches Heart Block Bundle Cardiology Female Wenckebach phenomenon medicine.symptom Cardiology and Cardiovascular Medicine business |
| Zdroj: | Journal of Electrocardiology. 3:193-209 |
| ISSN: | 0022-0736 |
| Popis: | Summary A combined study encompassing analysis of clinical electrocardiograms, use of a special diagram and intracavitary and His bundle electrograms before and during electrically-induced atrial tachycardia was undertaken in 18 patients with varying grade of heart block and 4 normal individuals. The purpose of the study was to ascertain the exact level of A-V conduction delay and blockage of the P waves. It has been shown that clinical tracings contain sufficient data in only a limited number of cases and in restricted circumstances. In the remaining cases, accurate localization of block could be achieved only after the study of His electrograms both before and during atrial pacing. Certain guidelines have been proposed for the analysis of tracings displaying Wenckebach periods, Mobitz II, complete block or a combination thereof. It has been emphasized that 2-1 A-V block is commonly a variant of the Wenckebach phenomenon, and that this type of block denotes bilateral bundle branch block only if certain stringent conditions are met. Likewise, complete heart block with BBB may reflect block at the A-V node or at the level of the bundle branches. It has been pointed out that the presence of His deflections after blocked P waves (spontaneous or induced by atrial tachycardia) indicates that the descending P waves have traversed through and beyond the A-V node, and, therefore, excludes the A-V node as the site of block. In such cases, block may be just at the bifurcation or lower at the level of both bundle branches. In conducted beats, long P-H intervals denote impaired conduction above the His bundle, while long H-Q intervals place the block in the bundle branches. Two types or retrograde V-A conduction have been documented. In one, the normal A-V pathways are employed, while in the other, pre-excitation or accessory pathways are used for propagation of the impulses from the ventricles to the atria. |
| Databáze: | OpenAIRE |
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