- TOO SHORT (< 0.12s)
Sinus Tachycardia
Probably due to adrenergic activation
- fever
- shock
- thyrotoxicosis
- beta-adrenergic agonists
Normal Sinus
- Congenital small AV node
- High dose corticosteroids
- Ventricular preexcitation (WPW): delta wave; widened QRS; abnormal QRS
Sinus Bradycardia
Causes:
- Acute myocardial infarction
- Drugs—for example, â blockers, digoxin, amiodarone
- Obstructive jaundice
- Raised intracranial pressure
- Sick sinus syndrome
- Hypothermia
- Hypothyroidism
- junctional escape rhythm with sinus P waves “marching through”