#EMConf: The Brady Bunch is on a DIET: A framework for bradycardia

Thu, 10/31/2019 - 5:00am
Author: 
Amanda Curry, MD
Editor: 
Loran Hatch, DO

The Brady Bunch

  • Beta-Blockers
    • Action: blocks AV node (predominantly at beta-1 receptor)
    • Differentiating sx: hypoglycemia, hyperkalemia
    • Treatment: 
      • Glucagon (5mg IV every 10 min x 3 doses)
      • High dose insulin (1 unit/kg bolus followed up 1 unit/kg/hr infusion)
      • Calcium
      • Intralipid (last resort)
  • Calcium channel blockers (non-DHP CCB are cardioselective i.e. verapamil, diltiazem)
    • Action: blocks AV node at L-type calcium channels
    • Differentiating sx: hyperglycemia
    • Treatment:
      • Calcium (3g IV, may need more)
      • High dose insulin
      • Glucagon
      • Intralipid 
  • Clonidine
    • Action: alpha-2 agonist to block sympathetic outflow from CNS
    • Differentiating sx: miosis, decreased respiratory drive, hypotension (looks like opioid overdose)
    • Treatment: 
      • Atropine
      • Supportive
      • Can try high dose naloxone (4-10mg IV)
  • Digoxin
    • Action: blocks AV node via inhibition of Na+/K+ ATPase on myocardium → leads to hyperkalemia 
    • Differentiating sx: visual disturbances, GI complaints, Salvador Dali sign on EKG (scooped ST wave)
    • Treatment:
      • DigiFab
      • IV lidocaine for ventricular dysrhythmias

DIET

  •  D - Drugs
    • The Brady Bunch
    • Amiodarone - bradycardia more common with chronic use, can more easily degenerate to torsades
    • Lidocaine
  • I - Ischemia, Infection, ICP
    • Ischemia: ACS
      • Tip: Atropine likely to be ineffective in inferior MIs, as RCA supplies AV node (atropine won’t work on infarcted tissue!)
    • Infection: Lyme, Viral myocarditis to name a few, but numerous others
    • ICP: increased intracranial pressure → herniation → Cushing’s triad
  • E  - Environment, Endocrine, Electrolytes
    • Environment: Hypothermia
      • Most profound with moderate to severe hypothermia (<82 degrees F)
    • Endocrine
      • Hypothyroidism: Myxedema Coma
        • Treatment: hydrocortisone, IV thyroxine (200-400mcg)
      • Hypoglycemia
    • Electrolytes
      • Hyperkalemia - treat with Insulin/dextrose, Ca, albuterol, etc
      • Hypermagnesemia 
      • Hypocalcemia - treat with IV Ca
  • T - Toxins
    • Cholinergics (pesticides, organophosphates)
      • Inhibit acetylcholinesterase at ganglionic and postganglionic synapse
        • Treatment with atropine (high doses) and pralidoxime (use early to avoid aging phenomenon!)
    • Opioids
    • Ethanol
    • Many others