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Finally we have a means of monitoring pace
Finally, we have a means of monitoring pace–sense conductor failure in an ICD lead. LIA™ (Lead Integrity Alert, Medtronic, Minneapolis, MN, USA) is a detection system for ICD pace–sense conductor failure [16]. Remote monitoring is also effective using this method of lead failure detection [17]. However, an HV short circuit is unlikely to be detected by this method. In previous case reports [1–3,7,9–13], the HV short circuit was only revealed after shock delivery, implying that shock delivery may be necessary in order to detect an HV short circuit. Our experiments have demonstrated that the pace–sense conductor is not involved in an HV short circuit mechanism. The potentially valuable deduction from our experiments is that if an HV short circuit occurs, the location is likely to be either in the pocket or inside the lead between the connector and the SVC coil.
Conclusions
Conflicts of interest
Introduction
Implantable cardioverter defibrillators (ICD) are an established form of therapy for both primary and secondary prevention of lethal cardiac arrhythmias [1]. Previous studies have shown that ICD implantation improves the quality of life (QOL) of most patients with ICD [2,3]. However, underlying diseases or comorbidity, poor social support, or ICD-specific problems such as frequent shocks and poor understanding of ICD therapy can increase anxiety and depressive symptoms and reduce QOL in patients with ICD [2,4,5]. Ten percent to 41% of the patients with ICD experience significant depressive symptoms, whereas general or ICD-specific anxiety occurs in 13–38% [6]. Some preliminary studies have suggested that psychological distress can precipitate arrhythmic events [7,8]. Moreover, a vicious ARCA may ensue, characterized by ICD implantation leading to anxiety and depression, which in turn precipitates arrhythmic events, leading to further distress [9].
Recently, trauma reactions, including post-traumatic stress disorder (PTSD), have garnered increased attention as a form of psychosocial distress that partly overlaps depressive symptoms or anxiety in patients with ICD [6,10–18]. According to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) [19], PTSD occurs in people who have been exposed to a traumatic event that involves actual or threatened death (criterion A). PTSD symptomatology is categorized into: (1) “intrusive recollection” (persistent re-experiencing of the traumatic event, criterion B); (2) “avoidant/numbing” (persistent avoidance of stimuli associated with the trauma and numbing of general responsiveness that was not present before the trauma, criterion C); and (3) “hyper-arousal” (persistent symptoms of increasing arousal that were not present before the trauma, criterion D).
ICD shocks are potential traumatic stressors in patients with ICD because they may act as continuous reminders of having a potentially fatal disease [10,11]. Traumatic events experienced by patients with ICD vary widely and are complex. Furthermore, even being told that they are at risk for life-threatening arrhythmias that could lead to sudden cardiac death (i.e., ICD implantation for primary prevention) may be traumatic for patients [6]. Therefore, threats to patients\' lives and well-being are not isolated events, but are persistent and enduring. Patients with PTSD symptoms may be particularly stressed by agonizing rumination and involuntary preoccupation with the underlying disease process [13].
To our knowledge, five published studies have assessed the incidence of PTSD after ICD implantation and estimated it at 7.6–26% [13–16]. However, these studies used disparate definitions of criterion A of PTSD (i.e., exposure to a traumatic event that involves actual or threatened death), presenting a methodological problem. Some reports classified rapid onset of the cardiac condition (cardiac arrest or acute myocardial infarction) as criterion A [13,15], whereas another used arrhythmia or its treatment (i.e., having an ICD) [14]. In the former, researchers excluded patients receiving ICDs for primary prevention. To cover patients with ICDs for both primary and secondary prevention, we believe that rapid onset of the cardiac condition, life-threatening arrhythmia, and ICD shocks should all separately qualify as meeting criterion A.