Moffitt Pearls – 11.14.17 – Complete Heart Block and Cardiac Sarcoid

Thanks you, Arvind, for presenting a case of an older man with exercise-induced bradycardia found to have complete heart block 2/2 to cardiac sarcoidosis.

KEY PEARLS:

  1. In the consideration of bradycardia, one must first rule out MI. 15% of patients with an MI will present with complete heart block.
  2. Bradycardia in an inferior or posterior MI is driven by 1) ischemia AND 2) the Bezold-Jarisch Reflex. This is a cardiovascular decompressor reflex involving a marked increase in vagal (parasympathetic) efferent discharge to the heart, elicited by stimulation of chemoreceptors, primarily in the left ventricle.
  3. Complete AV dissociation with Ps faster than SLOW QRSs suggests complete heart block.

Etiology of Bradycardia

Normal:

  • Healthy children/adults during sleep (HRs in 30s, pauses up to 2 seconds may occur)
  • Well-conditioned athletes
  • Some elderly patients

Abnormal:

An easy way to break down bradycardia is into extrinsic vs intrinsic causes.

  • Intrinsic
    1. Idiopathic degenerative d/o
    2. Ischemia (ACS or chronic)
    3. Lyme disease
    4. Viral myocarditis
  • Extrinsic
    1. Drugs – antiarrhythmics, b-blocker, calcium channel blocker
    2. Hypothyroid
    3. Hypothermia
    4. Hypoxia
    5. Vagal tone

 

Evaluation of Patient with Complete Heart Block

  1. Rule out Ischemia – ~15% of patient with an acute MI will have complete heart block (usually RCA)
  2. Check for systemic, reversible causes of heart block:
  • Meds: Digoxin, beta-blockers, calcium channel blockers, or anti-arrhythmics
  • Hypothermia
  • Electrolyte abnormalities – hypokalemia
  • Hypothyroid

3. Look for the primary cardiac causes in 3 broad categories:

  • Infiltrative: Amyloidosis, hemochromatosis, sarcoidosis
  • Inflammatory: SLE, scleroderma
  • Infectious: Rheumatic fever, Chagas, endocarditis, viral myocarditis,i syphilis, Lyme disease

Diagnostic Criteria for Cardiac Sarcoid

cardiac sarcoid

Here is a great JACC review on cardiac Sarcoidosis – http://www.onlinejacc.org/content/68/4/411

https://www.evernote.com/shard/s307/sh/6e60d9c4-b324-47bb-a162-03a79c64cb19/bde254d93bdd9f603bd4e3be123b31f2

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s