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Signature ✍️
- HR greater than 90-100 ⊕ sinus rhythm
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DDx 🏳️🌈
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- ↓ DO2*
- Hypotension DDx
- Hypoxia DDx
- Anemia DDx
- ↑ Metabolic Demand
- Fever, pain, psychiatric (e.g. anxiety)
- High-output state DDx
- Iatrogenic
- Albuterol nebulized
*DO2 = delivery of O2
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- ↑ Sympathetic Tone
- Exogenous
- Cocaine, (meth)amphetamine, MDMA
- Pseudoephedrine
- Anticholinergic toxicity
- Serotonin syndrome
- Endogenous
- Pheochromocytoma
- Adrenal infarction
- Dysautonomia
- POTS
- ↓ Sympathetic Dampeners
- Prescribed
- β-blockers & non-DHP CCBs
- α-2 agonists (e.g. clonidine)
- Benzodiazepine
- Recreational
- Alcohol
- Opioids
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Principles❗️
Diagnostic Arc 🗻
- 1st pass: the investigation of sinus tachycardia generally begins with a search for causes of “appropriate” sinus tachycardia, as these are both morbid (i.e. ↓ DO2) & common (fever, pain, psychiatric, iatrogenic)
✋ Pause ✋ : before moving on to “inappropriate” causes of sinus tachycardia, one must exclude early or compensated hypotension/shock states in which sinus tachycardia precedes hypotension, & in which the tachycardia represents hemodynamic instability in disguise…
- Cardiogenic: normotensive cardiogenic shock
- Obstructive: e.g. PE, tamponade, dynamic LVOT obstruction
- Distributive: e.g. occult sepsis
- Hypovolemic: retroperitoneal hemorrhage
- 2nd pass: if the thorough analysis above leaves you empty-handed, the investigation of sinus tachycardia then shifts to the patient’s history & exam, which often readily reveals the final answer, if you have asked the right questions (i.e. substance use history, medication reconciliation) & assessed the patient (e.g. visualized signs of sympathetic, anticholinergic, or serotonin toxicity)
Sinus Tachycardia ⊕ Tempo ⌛
- Sudden: “catastrophe vs. molecule”
- Cardiovascular Occlusion
- Pulmonary embolism
- Acute mesenteric ischemia
- Rupture
- Aortic dissection
- Retroperitoneal hemorrhage
- Molecule
- Exogenous (e.g. cocaine) vs. endogenous molecule (e.g. adrenal infarction)
- Withdrawal of molecule (i.e. sudden rebound of sympathetic tone)
- (Sub)acute, progressive: “the physiology is eroding”
- See [✋ Pause ✋] above
- Chronic, adynamic
- Often multifactorial, benign vs. irreversible (e.g. thoracic tumor compression of pulmonary vasculature)
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