Indian Pacing Electrophysiol. J.

ISSN 0972-6292

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Indian Pacing Electrophysiol. J. 2004;4(1):43-44                Arrhythmia Quiz 3

Arrhythmia Diagnosis Following an ICD Shock   Download PDF 102 KB

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 coronary artery disease, severe left ventricular dysfunction (LVEF 20%), first degree AV block and underlying QRS of 154 msec  underwent upgrade of an existing dual chamber ICD system with a Medtronic Insync Model 7272. The device was programmed to provide atrial synchronized biventricular pacing in the DDD mode. He experienced significant improvement in heart failure symptoms following cardiac resynchronization therapy. His ICD was programmed for single zone detection in the VF zone at 182 bpm with first shock therapy of 24J. Pacing was programmed in the DDD mode with lower rate limit of 70 and upper rate limit of 120ppm.

            He presents with an ICD shock while seated watching television. He had minimal prodromal symptoms prior to the shock although he admitted to being more dyspneic for the past two days. Data recovered during ICD interrogation is shown below:

Click here to enlarge

Click here to enlarge

Figure 1: Electrograms and markers obtained during ICD interrogation. The top and bottom panels show the onset and termination of arrhythmia respectively. In each panel, the following information is displayed from top to bottom: atrial electrogram, ventricular electrogram, atrial marker channel with cycle length and ventricular marker channel with cycle length.

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

1. A supraventricular tachycardia is a present
2. Programming of the ICD as a two zone device with activation of the SVT discrimination algorithm may have delayed or prevented this ICD shock
3. A ventricular tachycardia with 1:1 VA conduction is successfully terminated by the ICD shock
4. This arrhythmia is best treated with radiofrequency ablation of the AV node
5. Separate atrial and ventricular arrhythmias are present

Arrhythmia Quiz 3 - Answer

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