Cardiac arrhythmias in horses
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Heartbeat
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S1 = Signals closure of AV valves and start of systole
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S2 = Signals closure of semilunar valves and end of sytole
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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
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Clinical Findings
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ECG Findings
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2nd degree AV block
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- Slow/norm heart rate.
- Regulat irregular rhythm w. occasional dropped beats.
- Isolated S4 sounds.
- Pulse deficit.
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- Occasional P wave not followed by QRS.
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Sinoatrial block
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- Slow/norm heart rate.
- Regular rhythm w. long pauses.
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- Regular underlying rhythm w/ absence of P waves for > 2 PP intervals.
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Sinus arrhythmia
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- Slow/norm heart rate.
- Variable S1-S1 interval.
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- Variable RR interval ± wandering pacemaker (variable P-wave morphology).
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Last modified: Tuesday, 5 June 2012, 12:46 PM