Age-related changes in electrophysiology of the atrioventricular node and electrocardiographic manifestations

Atrioventricular conduction time increases with age, both due to atrioventricular nodal and His-Purkinje system changes. In the ageing process, structural and cellular electrophysiological changes as well as altered autonomic drive and negative chronotropic drugs play a role, The clinical differentiation between the atrioventricular node and the His bundle as a cause of diminished atrioventricular transmission is often relevant with respect to pharmacological and pacing strategies, However, it may appear irrelevant in the elderly in whom the atrioventricular conduction axis is mostly affected more diffusely, especially if underlying heart disease is present. One specific effect of ageing is the emergence of atrioventricular nodal tachycardias, where ageing of the atrioventricular node may set the stage for re-entry. (C) Rapid Science Publishers

Cardioversion of atrial fibrillation and subsequent maintenance of sinus rhythm

This article gives an overview of electrical cardioversion of AF and includes the discussion of newer strategies. DC external cardioversion is highly effective and carries a low risk of complications. Other approaches, like transesophageal cardioversion and high energy internal cardioversion, may improve the acute success rate but do not enhance long-term maintenance of sinus rhythm compared to external cardioversion. An atrial defibrillator may have important advantages which relate to the fact that the duration and possibly also the number of AF episodes become reduced. Supposedly, shortening the attacks of AF may exert an antiarrhythmic effect by limiting electrical, anatomical, and neurohumoral remodeling. So far, low energy biatrial defibrillation using an atrial defibrillator seems to be effective and safe (i.e., does not induce ventricular arrhythmias). However, discomfort limits its tolerability in clinical practice. Future improvement of leads and light sedation that is easy to administer may overcame this problem. In the second part of this overview, the probability of AF recurrence using a serial cardioversion approach is discussed. In middle-aged patients with a fair exercise tolerance and an arrhythmia duration <than 36 months this approach may be worthwhile. Young patients (age <57 years) with an arrhythmia duration <3 months and without hypertension may be cured from the arrhythmia with a single shock and without the institution of antiarrhythmic drugs. However, the serial electrical cardioversion approach is unlikely to succeed in elderly patients with a duration of AF exceeding 36 months and a poor exercise tolerance (NYHA Functional Class III or IV)

Pharmacological management of arrhythmias in the elderly

The incidence of cardiac arrhythmia increases with advancing age, as does the prevalence of structural heart disease. Serious arrhythmias, such as sustained ventricular tachycardias, are uncommon in elderly patients, but nonsustained ventricular tachycardias and atrial fibrillation are relatively frequent. The first step in the treatment of supraventricular and ventricular arrhythmias is the identification of an underlying (cardiac) disease, which should be treated appropriately. Patients with supraventricular arrhythmias who do not have a severe underlying cardiac disease may be treated with antiarrhythmic drugs to prevent recurrences of the arrhythmia. In selected patients, radiofrequency catheter ablation may nowadays be a first-line therapeutic strategy. In elderly patients with underlying cardiac disease who are experiencing non-life-threatening arrhythmias, antiarrhythmic drugs are generally discouraged because of the risk of proarrhythmic effects or other adverse events. In patients experiencing life-threatening ventricular arrhythmias, beta-blockers may be the first-line therapy. If these drugs are not effective, or cause adverse effects, class III or class IC antiarrhythmic drugs may be used as alternatives. Radiofrequency ablation is only moderately effective for haemodynamically stable ventricular tachycardias occurring post-myocardial infarction, but may be an option in drug-refractory patients