Indian Pacing Electrophysiol. J.

   ISSN  0972-6292

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Indian Pacing Electrophysiol. J. 2002;2(3):92

Arrhythmia Quiz 2


Arrhythmia Diagnosis Following an ICD Shock: Part II

Roy  M. John, MD, PhD, FRCP.

Address for correspondence: Roy M. John, MD, PhD, Section of Cardiology, Lahey Clinic  Medical Center, 41 Mall Road, Burlington, MA 01805. Email:



             A 70 year old male with history of coronary artery bypass surgery and depressed left ventricular ejection fraction of 30% presented with hemodynamically unstable sustained monomorphic ventricular tachycardia 5 years previously. He underwent implantation of a single chamber ICD. Six months ago, he experienced multiple ICD shocks for ventricular tachycardia and was placed on amiodarone, the maintenance dose of which was increased to 400 mg daily for arrhythmia recurrence. Two months ago, his ICD was upgraded to provide atrial synchronized biventricular pacing for progressive heart failure symptoms and marked sinus bradycardia. His underlying QRS duration was 160 msec. A Medtronic Attain OTW 4193 lead was placed in the posterolateral LV branch of the coronary sinus. This lead was connected in parallel via a bipolar connector with an existing Medtronic Sprint 6945 ICD lead in the right ventricle to the ventricular IS-1 port of an GEM III DR 7275 dual chamber ICD. Adequate atrial synchronized biventricular pacing was obtained in the DDDR mode. ICD detection was programmed for fast VT from 171 to 200 bpm and for VF above 200 bpm.

            The patient noted a marked improvement in exercise capacity after ICD revision. Two days ago, he experienced an ICD shock following a period of unusually strenuous exertion.  Electrograms obtained from ICD interrogation are shown in figure 1.

 Figure 1: (The top and bottom panels represent a continuous trace. In each panel, first channel shows atrial electrograms and second channel shows ventricular electrograms.)


Which of the following is a true statement regarding this arrhythmia?

  1. A supraventricular tachycardia is present
  2. There is oversensing of an atrial arrhythmia by the ventricular channel
  3. Atrioventricular association is present during the arrhythmia that leads to an ICD shock
  4. A left ventricular tachycardia is appropriately terminated by the ICD
  5. A slow right ventricular tachycardia is present

Arrhythmia Quiz 2 - Answer

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