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Vol. 72. Issue 10.
Pages 867 (October 2019)
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Vol. 72. Issue 10.
Pages 867 (October 2019)
ECG Contest
DOI: 10.1016/j.rec.2018.10.014
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Response to ECG, September 2019
Respuesta al ECG de septiembre de 2019
Albert Massó-van Roessel
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Corresponding author:
, Toni Perelló-Bordoy, Julián Palacios-Rubio
Servicio de Cardiología, Hospital Universitari Son Espases, Palma, Balearic Islands, Spain
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Rev Esp Cardiol. 2019;72:77710.1016/j.rec.2018.10.013
Albert Massó-van Roessel, Antoni Perelló-Bordoy, Julián Palacios-Rubio
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The correct response is option 3: this is an algorithm of Medtronic cardiac resynchronization therapy devices with automatic threshold-capture determination.1 Daily, at 01:00hours, the device first assesses the right ventricle (RV) with 3 support pacing pules (Vp) followed by 1 test pulse and 1 safety pulse at 90ms (Figure 1, asterisk). After completing this task, the frequency stability and V-V delay are checked (not apparent in the telemetry) and the device then searches for the left ventricular (LV) threshold. To do this, 3 support pacing pulses are applied followed only by another test pulse, without a safety pulse. Loss of capture from the left ventricle therefore leads to a pause if the patient does not have any intrinsic conduction or escape rhythm. In these cases, it is recommended to deactivate automatic threshold capture control, as it can cause ventricular arrhythmias triggered by sequences of short-long-short cycles.2

Figure 1

Response 2 is incorrect because the RV safety pulse prevents loss of capture. Response 4 is incorrect because there is no QRS complex and the warning is appropriate. Response 1 is also incorrect because the supposed dysfunction follows a pattern (3:1), indicating an issue with the algorithm and not true device dysfunction, which would who erratic behavior.

Manual de referencia para las familias de desfibriladores automáticos implantables digitales con terapia de resincronización cardíaca y tecnología SureScan™ Amplia MRI, Amplia MRI Quad, Compia MRI y Compia MRI Quad de Medtronic. Minneapolis: Medtronic; 2015. Disponible en: Consultado 15 Oct 2018.
M.O. Sweeney, L.L. Ruetz, P. Belk, T.J. Mullen, J.W. Johnson, T. Sheldon.
Bradycardia pacing-induced short-long-short sequences at the onset of ventricular tachyarrhythmias: a possible mechanism of proarrhythmia?.
J Am Coll Cardiol., 50 (2007), pp. 614-622
Copyright © 2018. Sociedad Española de Cardiología
Revista Española de Cardiología (English Edition)

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