Cardiac arrhythmia’s/dysrhythmias

Wikis > General Medicine > Cardiology > Cardiac arrhythmia’s/dysrhythmias

Cardiac arrhythmia’s/dysrhythmias

Common disorders due to abnormalities in impulse conduction and/or generation  abnormal rhythm; most often benign and asymptomatic – only occasionally severe and catastrophic

Aetiology:
• infarction  death of pacemaker or conducting cells
• disorder of cardiac connective tissue (eg fibrosis, rheumatic fever, sarcoidosis)
• hypertrophic cardiomyopathy
• autonomic nervous system control (eg stress, anxiety, exercise)
• drugs (eg caffeine, alcohol)
• metabolic/endocrine/electrolyte disorders (eg hypothyroidism, hyperthyroidism, hyperkalaemia, hypokalaemia)

Disorders of impulse generation:
1) Supraventricular – arise from ectopic foci in atria or AV node
a) Atrial flutter (
b) Atrial fibrillation (chaotic, rapid, irregular atrial rhythm; 300-600/min; in up to 9% of elderly; commonly caused by myocardial ischaemia, mitral valve disease, hyperthyroidism; present with palpitation and irregular pulse)
c) Supraventricular tachycardia/narrow complex tachycardia
2) Ventricular – arise from ectopic foci in ventricles
a) Ventricular fibrillation
b) Ventricular tachycardia/broad complex tachycardia

Disorders of impulse conduction:
1) Heart block
2) Re-entrant tachycardia

Clinical features:
Collapse, palpitations, chest pain, hypotension – often described as a ‘funny turn’

Management:
Treatment of associated illnesses; DC cardioversion

Pacemakers:
• lies subcutaneously to supply electrical initiation to cardiac contraction
• indicated for bradycardia, heart block

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