Overview
Sinus tachycardia originates from the sinus node and is a physiologic response that occurs due to changes in autonomic regulation - either sympathetic activation or reduction in parasympathetic tone.
Pathogenesis
Causes of Sinus Tachycardia
- Physical exertion
- Anxiety
- Pain
- Trauma
- Fever
- Infection
- Hypovolaemia
- Shock
- Hypoxia
- Anaemia
- Pulmonary embolism
- Coronary ischaemia / infarction
- Hypoglycaemia
- Thyrotoxicosis
- Phaeochromocytoma
- Drugs - beta agonists, anticholinergics, theophylline, caffeine, amphetamine, cocaine, alcohol
Diagnosis
ECG Findings
- Heart rate >100bpm
- Regular rhythm (RR interval)
- Each P wave followed by a QRS complex
- Positive P wave in leads I and II
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