inpatient / cardiology


Last Updated: 1/24/2023

# Bradycardia

-- ABCs: 
if unstable (low SBP, AMS, chest pain, SOB), give atropine1mg q3-5 mins up to 3mg, start transcutaneous pacing (give fentanyl or midazolam first), give epi if need for pressors, and get to ICU; glucagon if c/f beta blocker toxicity
-- Chart Check: prior EKG, echo; meds; prior heart disease or surgeries
-- Can't Miss: ACS, complete heart block, BB toxicity, hyperK
-- Admission Orders: telemetry, CBC, BMP, TSH, trop, EKG, echo,
-- Initial Treatment to Consider: oxygen, ACS pathway if needed, atropine, pacing, etc.

-- History: *** meds (BB, CCB, opioids), hypothyroid
-- Clinical/Exam: *** unstable (BP, AMS, chest pain, SOB), evidence of overload c/f CHF,
-- Data: *** EKG, Echo, TSH
-- Etiology/DDx: *** physiologic (athlete, sleeping), heart block, SSS, ischemia/ACS, increased vagal tone (OSA, pain, carotid hypersensitivity), inflammation (infection, amyloid, sarcoid, malignancy, autoimmune), infection (lyme, sepsis, endocarditis), meds (BB, CCB, amiodatone, opioids, SSRI), metabolic (AI, hypothyroid, hyperK, hypoCa), Cushing’s (increased ICP), hypothermia

The patient's HPI is notable for ***. Exam showed ***. Labwork and data were notable for ***. Taken together, the patient's presentation is most concerning for ***, with a differential including ***.

-- f/u EKG, place on continuous telemetry, consider echo
-- CBC, BMP, trop, TSH; lyme serology if in the right context

-- unstable - atropine 1mg q 3-5mins (up to 3mg) --> pressor (dopamine 5-20 mcg/kg/min vs epinephrine 2-10 ug/min) --> transcutaneous pacing --> transvenous pacing (ICU)
-- glucagon if c/f BB toxicity
-- consult to EP if e/o heart block or SSS
-- Permanent Pacemaker (PPM) indications - symptomatic sinus brady (+/- pauses), complete heart block, symptomatic second-degree heart block, syncope 2/2 bradycardia

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If You Remember Nothing Else

Unstable bradycardia (SBP <90, AMS, chest pain, SOB) needs acute management with atropine and escalation as needed. The underlying etiology should be investigated - top of mind should be heart block, ACS, and BB toxicity. Some processes are reversible, but in certain cases a pacemaker will be needed, so get the EP consultants involved.

Clinical Pearls

  • Bradycardia, while defined as HR <60, may not start to cause symptoms until HR <50
  • Atropine works by increasing activation of the SA and AV nodes - will not be helpful in patients with 3rd degree heart block and might be harmful if patient has an acute MI since it will lead to increased oxygen consumption of the heart
  • Sick Sinus Syndrome (SSS) is caused by dysfunction fo the SA node, which is the natural pacemaker of the heart
  • Heart block is a disorder of either the AV node or the conduction pathways of the heart; First-Degree is a stable delay in conduction between atria and ventricles; Second-Degree (Mobitz) is either a worsening delay leading to dropped beats in a predictable fashion (Mobitz Type 1, or Wenckebach) OR an unpredictable dropping of the beat (Mobitz Type 2); Third Degree (complete heart block) is when the atria and ventricles are completely disconnected and the ventricles are usually in an "escape" junctional rhythm.
  • A junctional rhythm is when the heartbeat originates from the AV node
  • Both SSS and heart block are most commonly caused by degenerative changes with age, but can also be precipitated by ischemia, cardiomyopathy, medications, and SLE or sarcoid

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