CASE: ‘Like a sledgehammer’
Mr. J, age 54, is admitted to the cardiac critical care unit after repeated tachycardia episodes over 3 years. He also has depressive symptoms including social isolation, passive suicidal thoughts, lack of interest in sex, weight loss, difficulty sleeping, sadness, and decreased appetite, energy, and ability to concentrate. The psychiatry consult team subsequently evaluates him.
Shortly after retiring as a police officer, Mr. J started having 10-second episodes of loss of consciousness and suffered 30 episodes within 1 year. After diagnosing chronic idiopathic ventricular tachycardia, a cardiologist ablated an aberrant left ventricular pathway and inserted a single-lead implantable cardioverter-defibrillator (ICD). He also prescribed the antiarrhythmic amiodarone, but Mr. J could not tolerate the medication’s side effects.
Mr. J’s tachycardia persisted, and repeated episodes triggered an estimated 13 electrical shocks from the ICD over 5 months. At this point, the cardiologist performed a second ablation, removed the single-lead ICD, and implanted a two-lead ICD, which he hoped would more accurately discern between lethal and nonlethal fast heart rhythms.
In addition, the cardiologist prescribed the antiarrhythmic sotalol—which did not suppress the arrhythmia—before switching to flecainide, 100 mg bid, which did. However, Mr. J still suffered fatigue, exercise intolerance, near-syncope, and chest heaviness.
One week after receiving the first ICD, Mr. J recalls, he felt his first shock while out for a walk. He said the shock lasted 5 to 10 seconds and “felt like somebody took a sledgehammer to my chest.” Another time, he suffered 6 successive shocks that threw him to the ground. Motorists pulled over to assist him, which made him feel ashamed.
Before long, Mr. J became increasingly afraid of repeat discharges. As soon as he began a task, he would feel a “thumping” in the back of his neck and start panicking, fearful that a heart rate increase would trigger another shock.
The stress forced Mr. J to abandon his favorite retirement hobbies—remodeling houses and yard work—and to spend his days lying around watching television. Fearing another discharge in public, he has stopped seeing friends and going to church. He has also stopped driving and depends on his female partner of 14 years for daily visits, grocery shopping, and rides to medical appointments. She feels frustrated by his debility.
The authors’ observations
By delivering electrical shocks when ventricles beat too quickly, an ICD shocks the heart back into a normal rhythm. Based on our observation, Mr. J probably had both anxiety-induced tachycardia and recurrent atrial fibrillation.
Although ICDs have prolonged survival for patients with potentially fatal ventricular arrhythmias,1,2 painful discharges can occur without warning. Patients liken the discharge to an electric shock or to being kicked or punched in the chest.3
Depending on the patient’s activity level, cardiologists routinely program ICDs to discharge at approximately 10 beats per minute above expected heart rates during typical activities. Because ICD leads cannot differentiate between ventricular and supraventricular rhythm disturbances, a rapid supraventricular rhythm might precipitate a discharge intended to treat a more serious ventricular rhythm disturbance.
Frequent ICD discharges could indicate:
- the patient needs a more effective antiarrhythmic
- the device needs to be set at a higher rate to avoid discharge during periods of anxiety/exertion
- or the device is defective.
ICD-induced psychopathology
Depression or tachycardia could have caused Mr. J’s fatigue. Either way, he showed numerous other depressive symptoms.
Fear of implant discharge or malfunction often induces psychiatric disorders, particularly in patients who have experienced discharge. As many as 87% of ICD patients suffer anxiety, depression, or other psychiatric symptoms after implantation,5 and 13% to 38% meet DSM-IV-TR criteria for an anxiety spectrum disorder.6
Multiple psychological theories explain iatrogenic anxiety disorders resulting from ICD firing. Behaviorally, ICD discharge represents an initially unconditioned stimulus that the patient associates with the activity he was engaging in when shocked. The shock discourages the patient from that activity—however benign—for fear it triggered the discharge and could cause future shocks.
ICD recipients often fear the device will malfunction or discharge while they are in public, driving, or operating machinery—leading some to become homebound and cease activities of daily living. The discharge’s unpredictability shatters a patient’s perception of control over his or her life and might induce a learned helplessness7 that can strain relationships, as it did with Mr. J and his partner. The patient also could develop anticipatory anxiety, mistaking benign body symptoms or increasing shock frequency for signs of a potentially fatal heart problem.8