It is in this context that
It is in this context, that the recent study of Matsuyama et al. sheds further light on the relationships between histoanatomy and atrial arrhythmogenesis . This investigation used high-density optical mapping to study atrial flutter/atrial fibrillation in isolated rat hearts . Atrial arrhythmia was induced in 15 of 19 hearts tested by programmed stimulation from the right atrium . Atrial arrhythmia in this model was predominantly initiated by a common re-entrant mechanism, with conduction slowing and block at the left atrial roof, with rapid antegrade conduction along the coronary sinus, providing the basis for a re-entry on the posterior wall of the LA.
For the first time, these findings were correlated with the intrinsic histology of the regions . Myocyte density was reduced and fibrosis increased on the roof and posterior LA compared to the CS . Myocytes in the LA roof had a broader distribution of cut lengths than in the CS, with more lateralised ghrelin receptor on Cx 43, providing a mechanism for this slower activation propagation . The data together provide crucial new information that links the basic histologic anatomy of with conduction abnormalities and arrhythmogenesis, even in the absence of conventional clinical disease markers.
Introduction An implantable cardioverter defibrillator (ICD) improves survival in patients at high risk of sudden cardiac death, including those with left ventricular dysfunction and heart failure . Many studies indicate that an ICD implantation improves the quality of life (QOL) for most ICD patients [2,3]. However, the severity of an underlying disease or comorbidities, poor social support, or ICD-specific problems such as younger age at implantation, frequent shocks, and a poor understanding of the therapy may increase anxiety and depressive symptoms in ICD patients [3–5]. Despite the effectiveness of an ICD in the prevention of sudden cardiac death, the implantation of an ICD and its concomitant therapies, including both appropriate and inappropriate shocks, can induce high levels of psychological distress such as depression, anxiety, anger, or posttraumatic stress symptoms in patients and their partners (Fig. 1). These psychological issues are major problems for patients receiving long-term ICD therapy; therefore, cardiologists and clinical electrophysiologists should screen for psychological distress and recommend appropriate referrals for these patients.
Depression Depression is associated with heightened morbidity and mortality in patients with cardiovascular disease [6–10]. It is also associated with sudden cardiac death in the elderly and women [11,12]. The prevalence of depression is reported to be 1 in 5 and 1 in 3 among outpatients with coronary artery disease and heart failure, respectively . In previous studies, depression has been observed in 24–33% of patients receiving ICD therapy . Bilge et al. reported that depression scores obtained using the Hospital Anxiety and Depression Scale were higher in patients who had an ICD for an extended period (>5 years) or in those who had received recent shock therapy (within the past 6 months) . Friedmann et al. also reported that Beck Depression Inventory scores were higher in patients who had an ICD for >1 year compared with those who had an ICD for <1 year . The Triggers of Ventricular Arrhythmia study suggested that moderate-to-severe depression is a predictor of appropriate shocks in patients with coronary artery disease and an ICD . However, few studies have evaluated changes in depressive state over time during ICD therapy. A small study of 25 ICD patients found that 2 of 5 patients with depression continued in this negative affective state for ≥1 year . Another study showed that depressive symptoms did not change in 132 ICD patients over 1 year, irrespective of whether they experienced shocks . A study of 57 ICD patients with heart failure revealed that the proportion of patients with depression decreased over a 2-year period, although follow-up was not completed for 50% of the enrolled patients . Using the Zung Self-Rating Depression Scale (index score ≥60), we reported that approximately 30% of 90 patients with an ICD had depression and that 72% of the patients with depression showed persistent depression at the 2-year follow-up (Fig. 2) . Patients with depression at 2 years had experienced more ICD shocks during this time than those without depression . Herrmann et al. showed that the percentage of psychologically distressed ICD patients increased with an increase in the number of shocks, especially in patients experiencing ≥10 shocks during the mean period of 1.4 years . Bilge et al. reported that depression scores according to the Hospital Anxiety and Depression Scale were significantly higher in patients who had experienced shocks recently (within the last 6 months) . These findings suggest that ICD shocks contribute to the persistence of depression in these patients.