Cardiac arrhythmias in horses

CARDIAC ARRHYTHMIAS IN HORSES

Heartbeat

  • S1 = Signals closure of AV valves and start of systole
  • S2 = Signals closure of semilunar valves and end of sytole
  • S3 = Heard if ↑ venous return; pregnancy
  • S4 = Assoc w/ atrial contraction. Immediately precedes S1. Can be heard in horses.

Cardiac Arrythmias in Horses

  • Always note
    • Vetricular Rate (normal, bradycardic, tachycardic)
    • Rhythm of 1st and 2nd heart sounds (reg or irreg)
    • Presence of dropped or premature beats
  • Most common equine arrythmias

Clinical Findings

ECG Findings

2nd degree AV block

  • Slow/norm heart rate.
  • Regulat irregular rhythm w. occasional dropped beats.
  • Isolated S4 sounds.
  • Pulse deficit.
  • Occasional P wave not followed by QRS.

Sinoatrial block

  • Slow/norm heart rate.
  • Regular rhythm w. long pauses.
  • Regular underlying rhythm w/ absence of P waves for > 2 PP intervals.

Sinus arrhythmia

  • Slow/norm heart rate.
  • Variable S1-S1 interval.
  • Variable RR interval ± wandering pacemaker (variable P-wave morphology).
Last modified: Tuesday, 5 June 2012, 12:46 PM