The development of sinoatrial dysfunction in pacemaker patients with isolated atrioventricular block

Postoperative atrial fibrillation

Postoperative atrial fibrillation (POAF) is common among surgical patients and associated with a worse outcome. Pathophysiology of POAF is not fully disclosed, and several perioperative factors could be involved. Direct cardiac stimulation from perioperative use of catecholamines or increased sympathetic outflow from volume loss/anaemia/pain may play a role. Metabolic alterations, such as hypo-/hyperglycaemia and electrolyte disturbances, may also contribute to POAF. Moreover, inflammation, both systemic and local, may play a role in its pathogenesis. Strategies to prevent POAF aim at reducing its incidence and ameliorate global outcome of surgical patients. Nonpharmacological prophylaxis includes an adequate control of postoperative pain, the use of thoracic epidural analgesia, optimization of perioperative oxygen delivery, and, possibly, modulation of surgery-associated inflammatory response with immunonutrition and antioxidants. Perioperative potassium and magnesium depletion should be corrected. The impact of those interventions on patients outcome needs to be further investigated.

Pacing therapy in the elderly

Bradycardia due to sinus node dysfunction and atrioventricular block is more commonly observed in the elderly. Aging is associated with progressive fibrosis in both the sinus node and atrioventricular conduction system (AV node, His bundle, right and left bundles). In the absence of reversible causes implantation of a permanent pacemaker is often required in the patient with symptomatic bradycardia. For elderly patients with sinus node dysfunction, pacing modes that preserve atrioventricular synchrony are associated with a reduced incidence of atrial fibrillation and improved quality of life. For patients with atrioventricular block, the importance of preserving atrioventricular synchrony in the elderly is controversial and is currently being evaluated.