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Vol. 71. Issue 6.
Pages 489 (June 2018)
Vol. 71. Issue 6.
Pages 489 (June 2018)
ECG Contest
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Response to ECG, May 2018
Respuesta al ECG de mayo de 2018
Ignacio Gil-Ortegaa,
Corresponding author

Corresponding author:
, Beatriz Garrido-Corrob, Juan Antonio Castillo-Morenoc
a Unidad de Arritmias, Hospital Universitario Santa Lucía, Cartagena, Murcia, Spain
b Farmacia Hospitalaria, Hospital Universitario Virgen de la Arrixaca, El Palmar, Murcia, Spain
c Servicio de Cardiología, Hospital Universitario Santa Lucía, Cartagena, Murcia, Spain
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Rev Esp Cardiol. 2018;71:39410.1016/j.rec.2017.11.031
Ignacio Gil-Ortega, Beatriz Garrido-Corro, Juan Antonio Castillo-Moreno
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The correct solution is number 4. Figure 1 shows atrial T wave activity, with atrioventricular block, reset of sinus rhythm, and subsequent symptomatic bradycardia. Figure 2 shows the same sequence, with atrioventricular conduction, both of sinus rhythm and extrasystoles, without bradycardia or symptoms. Of note is the perfect alternans of right and left branch aberration. Cohen et al.1,2 described this phenomenon as split atrial activity and explained it by the presence of an occult retrograde penetration of the His-Purkinje system.

Figure 1
Figure 2

In the absence of extrasystoles, the patient showed stable sinus rhythm, with adequate chronotropic control. Therefore, the patient does not have sinus dysfunction or structural branch block alternans. Instead, the abnormality is caused by atrial extrasystoles, leading to retrograde capture of the conduction system. Thus, neither pacemaker placement (answer 1, incorrect) nor drug withdrawal (answer 2, incorrect) would be justified. Likewise, sinoatrial block is not present (answer 3, incorrect) as the electrocardiographic criteria are not met.


H.C. Cohen, I. D’Cruz, E.R. Arbel, R. Langendorf, A. Pick.
Tachycardia and bradycardia-dependent bundle branch block alternans: clinical observations.
Circulation., 55 (1977), pp. 242-246
H.C. Cohen, I.A. D’Cruz, A. Pick.
Effects of stable and changing rates and premature ventricular beats on transient tachycardia-, pseudobradycardia-, and bradycardia-dependent bundle branch block alternans.
J Electrocardiol., 12 (1979), pp. 151-156
Copyright © 2017. Sociedad Española de Cardiología
Revista Española de Cardiología (English Edition)

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