Materials and methods

At the Freeman Hospital, Newcastle upon Tyne, ICD treatment is only recommended to patients with ventricular arrhythmias after comprehensive assessment and detailed discussion of their risk of recurrent episodes, the range of alternative therapies available, and the nature of device therapy. Patients receiving ICDs are those with either very poor left ventricular function or major non-cardiac co-morbidity making surgery inappropriate, or those with idiopathic ventricular fibrillation. Based in these criteria, ICDs have been implanted in 35 patients from 1989–95. All patients are followed up at regular intervals at a dedicated defibrillator clinic staffed by an electrophysiologist and a cardiology technician. Psychological status was not systematically assessed at these review appointments. Patients are also encouraged to make contact with the hospital between scheduled visits if they experience shocks. They are reviewed routinely within 24 hours of shock therapy for reassurance and device interrogation.

Results

Of the 35 patients who received ICD therapy at this hospital in the period studied, six (17%) developed psychological problems that were sufficiently florid to prompt urgent referral for formal psychiatric evaluation. The cardiology background of each of the patients and the events precipitating the subsequent psychopathology are summarised in table 1. The most frequent manifestations of psychopathology were profound anxiety and panic reactions centred on fear of future shock therapy. Two patients also showed depressive reactions. Table 2 summarises the nature and severity of the psychopathology identified and the management and outcome in each patient.

Discussion

The typical symptoms reported by this patient group were of generalised anxiety, manifest as palpitations, sweating, tremor, abdominal churning, and restlessness. There were also phobic anxiety symptoms, including complete agoraphobia in two. This was a panic reaction to leaving the safety of home; however, the agoraphobia was unusual in that it was linked entirely to thoughts about further shocks from the implanted defibrillator and imminent death, and not to fears of being unable to escape from crowds or crowded places. Panic symptoms with hyperventilation, paraesthesia, palpitation, difficulty in breathing, and chest pain were often present when these thought sequences occurred.

Two patients were also depressed after experiencing multiple shocks from their ICD and their symptoms included sadness, insomnia, loss of energy, loss of interest, poor appetite, and suicidal thoughts. There were prominent thoughts of hopelessness about the future. The two patients with depression also suffered from prominent anxiety symptoms.

Multiple shocks were a clear precipitant for the psychiatric disorders. The thought processes resulting from this particular event were central to the subsequent psychopathology as described in table 2 according to the International Classification of Mental and Behaviourial disorders.14 Indeed, all six patients reported profoundly anxiety provoking thoughts in relation to the defibrillator, often linked to withdrawal from social interaction.

One dominant thought pattern was identified in all six patients in this group: “If the device fires I’m going to die”. This catastrophic thought about the purpose of the device fed straight into the panic cycle.15 In the panic cycle, normal stressful reactions leading to palpitation and tension headache are misinterpreted as being about to lead to catastrophic events, such as sudden death from myocardial infarction or stroke. The cycle escalates because of these thought sequences, leading to more anxiety, which in turn generates more symptoms, such as hyperventilation and paraesthesia, leading to difficulty in breathing and chest pain. In the face of this spiralling anxiety, many patients reach extremely severe levels of anxiety, which may actually precipitate tachyarrhythmias. In the face of such anxiety, two patients withdrew from social interaction altogether.

There are a number of methods of helping patients interrupt this anxiety cycle. Appropriate interventions should begin with education as to the nature and purpose of the defibrillator. The typical spectrum of anxiety and depressive symptoms needs to be explained and put into proper perspective. Appropriate patient orientated information literature is already available to give to patients suffering from anxiety disorders16 and depression17 to explain their symptoms and suggest ways of containing them. This helps the patient to realise that palpitations are not necessarily cardiac in origin, but relate to the generalised stress being suffered at the time. In conjunction with this, muscular relaxation and breathing exercises, delivered on a relaxation tape, help patients to work at reducing their general anxiety response and so control hyperventilation. A number of rational responses have been found to be helpful in the management of these patients, but they need to work hard to learn them and to appreciate their use in controlling their catastrophic thinking—for example, “A palpitation is often only anxiety, it doesn’t always mean the machine is about to fire”; “The device is a tried and trusted treatment. It effectively stops the arrhythmia”; “The device is an ally not an enemy”; “Life would be very unpredictable without the implanted defibrillator”; “My best chance here is to be kind to the heart and remain calm”. With practice, such self statements or rational responses have proven useful in panic related to other precipitants18 and in other situations such as depression.19

Now that the adverse ways in which some patients may react to their implanted defibrillator are understood, psychopathology may be reduced or prevented completely by training patients to develop rational responses in anticipation of shock therapy. Using patient and other support groups, the process of developing these rational responses could begin before ICD implantation. When severe psychopathology presents acutely, treatment with β adrenergic blockade, benzodiazepines, and antidepressants may all be indicated. Benzodiazepines and low dose diazepam in particular should only be used for four to six weeks at most to avoid drug dependence and the development of tolerance and symptoms of breakthrough withdrawal. Antidepressants may be indicated in patients with depressive symptoms. As paroxetine has been licensed both for the treatment of panic disorders and depression and has less arrhythmogenic potential than some alternative antidepressant drugs,20 it may be particularly useful in this population.

Lesser degrees of psychopathology can be easily missed in cardiology clinics. Patients should therefore be questioned routinely regarding anxiety or depressive symptoms and their level of social functioning. The self-administered Hospital Anxiety and Depression rating (HAD) questionnaire, which can be completed in two to three minutes and does not rely on somatic symptoms of anxiety, could be a useful additional screening tool in this setting.21