Arrhythmia Diagnosis Following an ICD Shock.
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 60 year male presents to the emergency room following a shock from
his implanted cardioverter defibrillator.
He had just risen from bed that morning and experienced mild dizziness
prior to the shock.
He has a history of hypertension, and had undergone coronary bypass
surgery 3 years previously. Six months following surgery, he developed
spontaneous rapid sustained monomorphic
ventricular tachycardia associated with syncope. Therapy with amiodarone was complicated by acute pneumonitis requring
steroids and cessation of amiodarone
therapy. He was implanted with a Ventritex
Model V 145 single chamber ICD. A recent echocardiogram had
shown inferior and posterior left ventricular hypokinesis
with an ejection fraction of 35%. Left atrium measured 4.4 cm. His
medications included metoprolol 25 mg bid,
lisinopril 5mg bid, hydrochlorthiazide
25 mg qd, atrovostatin
10 mg qd, and aspirin 325 mg qd. Physical examination
revealed normal jugular venous pressure, sinus rhythm with a heart rate
of 84 bpm, BP 140/85, a soft pansystolic
murmur
at the apex, and clear lung fields.
A continuous rhythm strip obtained during interrogation of the ICD is
shown in the figure as 4 panels from top to bottom. The device is
programmed
for two zone detection and therapy: VT zone between 350 and 300 mec with anti-tachycardia therapy followed by cardioversion, and VF zone below 300 msec programmed for defibrillation therapy.
Which of the following statements is correct regarding this patient’s
arrhythmia diagnosis and management?
1.
There is evidence for malfunction of the ICD system
2.
Atrial fibrillation organizes to atrial flutter following anti-tachycardia pacing
3.
Appropriate therapy was delivered and the patient should be
discharged home with no alteration in his medication
4.
A pro-arrhythmic effect of ICD therapy is evident
5.
Recommence amiodarone
Figure for Arrhythmia Quiz:
Arrhythmia Quiz - Answer
