Prolonged PR Interval
April 24th, 2019
Overview
Also known as first degree heart block; a prolonged PR interval suggests delayed conduction between the atria and the ventricles.
Look For
- PR interval >200ms (5mm).
Causes of First Degree AV Block
Intrinsic (AV Nodal)
- Idiopathic degeneration
- Myocardial infarction
- Congenital - congenital heart disease, neonatal lupus
- Infiltrative disease - sarcoidosis, amyloidosis, haemochromatosis
- Cardiac procedures - valvular surgery, correction of congenital heart disease, catheter ablation
- Systemic lupus erythematosus
- Myocarditis
Extrinsic
- Physiologic - sleep, athletes
- Autonomic - carotid sinus massage, carotid sinus hypersensitivity
- Drugs - beta blockers, calcium channel blockers, digoxin, adenosine, amiodarone
- Hyperkalaemia
- Hypothyroidism
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