Equine Arrhythmias

Emma Dunseath
Flowchart by Emma Dunseath, updated more than 1 year ago
Emma Dunseath
Created by Emma Dunseath over 2 years ago


Veterinary Medicine (Module 15) Flowchart on Equine Arrhythmias, created by Emma Dunseath on 05/02/2018.

Resource summary

Flowchart nodes

  • Heart Rate
  • Bradycardia
  • Tachycardia
  • Dropped Beats
  • No dropped beats
  • S4 heard
  • S4 not heard
  • 2' AV block
  • 2' SA block
  • HR <20
  • 3' AV block
  • V irreg rhythm
  • Regular rhythm
  • occ extra beat
  • S4 not heard
  • Atrial fibrillation
  • compensatory pause after extra beat?
  • Ventricular tachycardia
  • VPC
  • APC
  • Supraventricular tachycardia
  • Mobitz type 1 is non-pathogenic reg -irreg, Type 2 is pathogenic, irreg-irreg
  • Whole complex is missed, insignificant unless HR <20
  • AVN disease, inflamm or degenerative, K imbalance, or digoxin
  • causes an exercise intolerance because HR fails to increase
  • QRS without P
  • Tx: correct elec imbalance or underlying cause. If there is an inflam stimulus, consider corticosteroids. Phenytoin in chronic cases (Na channel blocker
  • P with no QRS
  • systolic murmur common from V contraction while AV valve open
  • Large atria with carcadian movement of impulses, or high vagal tone cuase refractory period to be different in different cells
  • non pathological, exercise resolves, but may be recursor to AF
  • Ventricular atopic beats
  • Tx if HR >100, there are runs, or R on T phenomenon. Procainamide infusion, Lidocaine infusion with MgSO4
  • Cardioversion therapy for Atrial fibrillation
  • Less successful conversion if >6 duration, underlying cardiac disease exists. Poorer prognosis if there is a pathological murmur with volume overload, if HR >55, or previous treatment was unsuccessful
  • Oral boluses of Quinidine Sulphate: 22mg/kg via stomach tube q2hr, max 5 doses. Vagolytic and prolongs AP so increases the refractory period.
  • Risk severe ventricular tachycardia if Vs start responding to every AF Other Signs of toxicity include depression, D+, colic, muzzle swelling, weakness, laminitis, hypotension and collapse leading to death Managing SEs: Stop dosing, give mineral oil to decrease further absorption. NaHCO3 to increase protein binding of QS, Lidocaine IV for VT tx if rate >100bpm, MgSO4 if Tsordes de pointes develops (Ca channel blocker so staibilises membranes)
  • Electric Shock therapy Can be attempted under GA if unresponsive to medical therapy. Use echo examination to determine suitability
  • Non-Pathological Dysrrhythmias 2'AV block, Sinus Block, Sinus arrhythmia, APC, VPC (1 or 2 in 24hr) Pathological Dysrrhythmia 3' AV block, Sinus Bradycardia, AF, APC, VPC, VT
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