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: roy.m.john@lahey.org
Question:
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?
- A
supraventricular tachycardia is present
- There is
oversensing of an atrial arrhythmia by the ventricular channel
-
Atrioventricular association is present during the arrhythmia that
leads to an ICD shock
- A left
ventricular tachycardia is appropriately terminated by the ICD
- A slow right
ventricular tachycardia is present
Arrhythmia Quiz 2 - Answer
