Clinical Case 5 - Page 2

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Courtesy of C. Antonczyk

Mikey was admitted for an electrocardiogram, echocardiography and thoracic radiographs. The ECG is shown below:

ECG recording in lead II 25mm/sec 10mm/mV

(Courtesy of C. Antonczyk)

(Courtesy of C. Antonczyk)

In order to reveal an answer, highlight the underlined or bulleted area using your mouse. 
The number of bullet points doesn't necessarily indicate a strict number of answers. 

For what reason might you perform an ECG?

• In order to diagnose a rhythm disturbance.

What is the average heart rate on the first half of this ECG?

• This recording is 25mm/sec, so 25 of the small boxes represent a second and 5 of the larger boxes represent a second. If you count the number of beats starting from the first thick line over the following 4 seconds (20 of the larger squares) you get 15 beats. So in 4 seconds there were 15 beats. Hence in one minute there will be 15x15 beats. The average heart rate is 225 beats per minute.

Can you see any P waves? Why do you think this might be?

• No. This dog has atrial fibrillation. P waves are absent.

On the first half of the ECG, why does the 6th complex look different to the rest?

• This complex is wider than the others indicating that it is of ventricular origin. It is a ventricular premature complex (VPC)

On the second part of the ECG, what do we call the series of abnormal complexes?

• This is a run of VPCs. As there are more than three in succession, this is called ventricular tachycardia.

Click here to see the results of the ultrasound.