Atrial fibrillation in dialysis patients

Atrial fibrillation is frequently observed during dialysis Epidemiology and classification of atrial fibrillation sessions. As a rule it stops spontaneously without therapeutic intervention 2–3 h after the dialysis Atrial fibrillation is regarded as the most frequent session [2]. supraventricular cardiac arrhythmia. Its incidence in the adult population is 0.5%. The probability of developing atrial fibrillation rises with increasing age. The Framingham study reports an incidence of 0.4% for Clinical features persons under 30 years, whereas atrial fibrillation is observed in 2–4% of persons aged over 60 years. The clinical presentation of atrial fibrillation depends Secondary forms resulting from cardiac and extramainly on the rate of ventricular contraction. Whereas cardiac diseases must be distinguished from the rarer atrial fibrillation of normal frequency is mostly asympprimary (idiopathic) forms of atrial fibrillation without tomatic, ‘palpitations’ are typically reported at a high concomitant cardiac disease ( lone atrial fibrillation) ventricular contraction rate. Apart from the high vent[1]. ricular contraction rate, the underlying cardiac condiWithout consideration of the aetiology and for tion is crucial for clinical presentation, i.e. angina reasons of practicability, atrial fibrillation is subdivided pectoris, dyspnoea, pulmonary oedema. Vertigo or clinically into: orthostatic dysregulation are frequent, and even syncope may occur. (i) Paroxysmal atrial fibrillation, which occurs episodically and converts spontaneously into sinus rhythm within 48 h at the most. (ii) Persistent atrial fibrillation, which is sustained for Haemodynamics longer than 48 h, but which continues to be convertible into sinus rhythm. Not only the atrial primer pump function (atrial ‘kick’), (iii) Permanent atrial fibrillation, which can no longer but also the powerful synchronous atrial contraction be converted into sinus rhythm with conventional is lost when atrial fibrillation occurs. Consequently, treatment measures. development of atrial fibrillation causes relevant clinThe classification is clinically relevant since paroxical and haemodynamic deterioration, especially in ysmal atrial fibrillation can be converted by medication elderly people [4]. or by electrical means without prior anticoagulation, At present a major increase in volume of the right whereas an attempt at conservative treatment is no and left auricles is viewed by some authors [5] as a longer appropriate in patients with permanent atrial further potential factor predisposing to atrial fibrillafibrillation. If clinical symptoms are present, invasive tion. This is particularly relevant for patients undertreatment should be considered. In persistent atrial going dialysis. fibrillation, effective anticoagulant treatment for at Haemodynamic impairment is in part explained by least 3 weeks is indicated before attempting conversion, shortening of the diastole and impaired left ventricular in order to avoid thromboembolic complications. filling. In part, however, it is also due to altered systolic Since atrial fibrillation tends to occur in cases with contractility. The staircase phenomenon (Bowditch’s cardiac pathology, it is not surprising that intermittent treppe) implies that cardiac contractility increases as atrial fibrillation occurs in dialysis patients (16%) heart rate goes up until a maximum is reached. This significantly more often than in the general populamaximum differs from individual to individual, tion [2]. depending on the state of training and underlying In the Canadian Multicenter Study, pathological cardiac disease. In patients with a high ventricular echocardiographical findings were seen in 75% of contraction rate the peak of Bowditch’s is reached at patients admitted for renal replacement therapy [3]. heart rates of no more than 80–90/min, so that any further increase of heart rate leads to a progressive decrease of cardiac contractility (‘tachycardia Correspondence and offprint requests to: Prof. H. Zebe, Fachklinik Der Fürstenhof, Brunnenalle 39, D-34537 Bad Wildungen, Germany. cardiomyopathy’).