The use of heart rate histogram in arrhythmia diagnosis

A patient was brought in due to altered level of consciousness. While on telemetry this was noted.

Image 1

This is a regular narrow QRS tachycardia (~150 bpm). The P waves are difficult to see.

This could mean a number of things - supraventricular tachycardia (SVT) with the P burried in the QRS (AVNRT - AV nodal reentry tachycardia,atrial tachycardia, atrial flutter with 2:1 conduction considering its rate of 150 bpm, junctional tachycardia and sinus tachycardia with a long PR interval).

One simple tool to use is the Heart Rate Histogram or Heart Rate Trend.

Image 2 - Heart Rate Trend

There is gradual increase and decrease in the heart rate. This would mean one thing. This is sinus tachycardia.

Image 3 - 12L ECG

A 12L ECG was done and captured the rate at about 110 and the machine read it as accelerated junctional  rhythm. LOOK CLOSELY AT V1, there is nib at the terminal part of the T waves. Those are the P waves. The 12L is SR with long PRI (~ 280 ms). 

So the featured case is sinus tachycardia with a long PRI. 

What happened to the patient? Brain MRI was negative for acute stroke. EEG supported seizure and patient was started on anti-seizure medication and later discharged.

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