7.4 The pathophysiology of conduction abnormalities and arrhythmias
Myocardial cell damage affects the electrophysiological features of the cell membrane and can result in the development of arrhythmias. This is principally caused by damage to the ion pumps and channels which determine the shape of the action potential (see section 1.5.2). The exact type of arrhythmia depends on the location of the damaged tissue and the extent of the damage. Autonomic factors, electrolyte levels and drugs may also affect the membrane potential and influence the genesis of arrhythmias. In general, myocardial cell damage results in a decreased resting membrane potential, slowed depolarisation (phase 0), and a shortened action potential plateau (phase 2).
Some arrhythmias result from conduction block, which can affect rhythm directly or which can lead to the development of re-entrant arrhythmias. Other arrhythmias result from abnormal impulse formation.
7.4.1 Abnormal impulse conduction
7.4.2 Abnormal impulse formation