Bloqueo AV completo durante el ejercicio

 Abstract

Exercise-induced atrioventricular (AV) block in patients with normal electrocardiogram at rest is uncommon. We report the clinical features of two patients with AV block during treadmill test. The first patient was a woman of 54 years of age with presyncope on exercise. She developed complete AV block during exercise testing without evidence of ischemic myocardial disease. Electrophysiologic study documented distal AV block. The second patient was a man 31 years old who developed angina and third-degree AV block with depression of ST segment during treadmill test. Myocardial perfusion study suggested ischemic heart disease. He received anti-ischemic drugs with improvement of symptoms. A control exercise testing demonstrated normal AV conduction and electrophysiologic study was normal. In the first case, exercise AV block was probably due to abnormal His Purkinje conduction system refractoriness to autonomic modulation, while in second case AV block was secondary to ischemic heart disease. Third-degree AV block at exercise can be present in patients without conduction system abnormalities at rest. Exercise-induced infra-Hisian AV block must be treated with pacing until ischemic heart disease has been ruled out. *1

Abstract

In this report we describe the case of a 56-year-old woman with normal 1:1 AV conduction at rest who developed 2:1 AV block during treadmill exercise testing. Electrophysiological study documented 2:1 AV block proximal to the His bundle with reappearance of 1:1 AV conduction at a higher pacing atrial rate. A gap phenomenon involving a proximal and distal part of the AV node may be a likely explanation of paradoxical AV conduction in our case.*2

Abstract

Exercise-induced atrioventricular block in patients with normal atrioventricular conduction at rest is uncommon. Electrophysiologic studies have documented block distal to the atrioventricular node in these patients. Implantation of a permanent pacemaker is recommended because of a high incidence of subsequent symptomatic block. We report three symptomatic patients with exercise-induced atrioventricular block. Two patients showed a bundle branch block in the baseline electrocardiogram, suggesting a distal location of the block. In the remainder, with a normal QRS, the electrophysiologic study revealed AV block within the His bundle in response to atrial pacing.*3

Abstract

Three patients with 1:1 atrio-ventricular conduction at rest developed fixed 2nd or 3rd degree atrio-ventricular block during exercise testing. In all patients electrophysiologic study documented block distal to the atrioventricular node. The exercise induced block probably occurred because of increased atrial rate and abnormal refractoriness of the His-Purkinje conduction system. These findings suggest that high degree atrioventricular block appearing during exercise reflects conduction disease of the His-Purkinje system rather than of the atrio-ventricular node, even in absence of bundle branch block. These patients should be considered for permanent cardiac pacing.*4

Abstract

Four personal cases of exercise-induced conduction defects occurring during stress testing are reported. The significance of these changes is discussed in the light of the authors' observations and of the cases published in the literature. The development of atrioventricular block is usually related to pre-existing disease of the conduction system, whilst left anterior or posterior hemiblock is usually due to transient ischaemia related to significant stenosis of the coronary artery responsible for the vascularisation of the relevant bundle branch (usually a proximal stenosis of the left anterior descending artery). Complete left bundle branch block may be due to a number of conditions (including chronic ischaemic heart disease).*5

*1 A complete atrioventricular block during exertion]

[Article in Spanish]

A Medeiros et al. Arch Inst Cardiol Mex. 1999 May-Jun.

*2Exercise-induced second-degree atrioventricular block

Loukas K Pappas et al. Int J Cardiol. 2006.

*3Exercise-induced atrioventricular block

[Article in Spanish]

J M Barbero et al. Rev Esp Cardiol. 1993

*4 Intermittent atrio-ventricular block induced by exertion. Description of 3 cases]

[Article in Italian]

M Barra et al. G Ital Cardiol. 1985 Nov.

*5 Significance of exercise-induced arrhythmias]

[Article in French]

D M Marcadet et al. Arch Mal Coeur Vaiss. 1988 Aug.