Rhythm Nation

EKG Case 7 Answer

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ekg atachHere is the answer for our last EKG:

Rate:  300

Rhythm: Sinus rhythm – although the P waves are difficult to discern in the rhythm strip, they are visible in V1.  Mapping the P waves in V1 to the rhythm strip, you can see that the P waves in lead II are downgoing waves that occur immediately after the end of the T wave.  The wide complex beats that occur at irregular intervals are PVCs.

Axis:  Normal axis

Intervals: PR about 160ms; QRS borderline at 120ms with a RBBB pattern;  QT about 280ms which gives  QTC about 430ms

ST segments: T waves are discordant with the QRS in almost every lead.  No ST segment depressions or elevations

Chambers – no signs of LVH or atrial enlargement;  The negative P wave in inferior leads may indicate an ectopic atrial pacemaker causing abnormal direction of conduction of the atrial impulse.

This is a case of atrial tachycardia.  The P wave is originating from an ectopic focus.  The atrial rate is fast (>100bpm).  The paves are consistent throughout the EKG which makes multifocal atrial tachycardia unlikely.  The baseline is isoelectric, which makes atrial flutter less likely.

The treatment of atrial tachycardia varies depending on the cause and the stability of the patient.  Unstable patients may require cardioversion.  Antiarrhythmic therapy is also an option, and catheter ablation may be considered in patients with recurrent episodes and a single ectopic focus.

Thanks to Carl for submitting this EKG!

 

The views expressed on this blog are the author's own and do not reflect the views of their employer. Please read our full disclaimer here. Any references to clinical cases refer to patients treated at a virtual hospital, Janus General Hospital.
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nchristopher

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1 comment for “EKG Case 7 Answer”

  1. Ian deSouza
    June 20, 2013 at 7:34 pm

    Nice ECG and review. Some more:

    The key is the consistent AND abnormal p wave morphology. If you look at lead II the p wave is primarily negative (downward) in its vector and a normal p would be positive (upward). This means there is an abnormal p axis which implies an ectopic atrial focus.

    The mechanism of an ectopic atrial tachycardia is abnormal automaticity – that is, a group of cells generate rhythmic impulses when they are not supposed to. Automatic dysrhythmias WILL NOT respond to cardioversion. Increased sympathetic tone often triggers these rhythms, so beta-blockers is a good first choice of medications. Definitive treatment involves catheter ablation.

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