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. 2013 Jan 22;2013:976976. doi: 10.1155/2013/976976

Table 2.

Electrophysiological differences between the elderly and young that can predispose to AF (summarised from human and animal studies in Table 1).

Features Elderly Young
Impulse initiation
 (i) Sinus node function Impaired (leading to longer sinus node recovery times), contributing to abnormal impulse initiation Generally preserved
  (ii) Pulmonary vein ectopic activity Also contributes to AF pathogenesis although substrate abnormalities have a dominant role in initiation and maintenance Predominant trigger for AF initiation

Impulse conduction
  (i) P wave morphology and duration (usually signifying interatrial conduction) Abnormal P wave morphology and prolonged interatrial conduction Usually normal
  (ii) Wavefront propagation Abnormalities noted such as conduction slowing (particularly of premature impulses) thereby contributing to reentrant waves Usually normal

Substrate abnormalities
  (i) Complex fractionated atrial electrograms Greater number Lesser than in elderly
  (ii) Atrial refractoriness—effective Refractory Period (ERP) ERP prolonged in the right atrium and could contribute to dispersion in refractoriness Usually not prolonged
  (iii) Action potential duration (APD) Prolonged in the right atrium Generally within normal limits
  (iv) Regional atrial voltage differences Larger atrial volumes with more number of low voltage areas Atria usually of normal size and mean voltage within normal limits