A canine EKG, or electrocardiogram, is a procedure that records the electrical activity of the heart through electrodes attached to the skin. The EKG can be an important diagnostic tool in a physical examination and should also be monitored closely any time a dog is placed under an anesthetic. The EKG is also the only test available to diagnose an arrhythmia or abnormal heart rhythm.
Things You'll Need
- Calipers
Instructions
Determine the paper speed in milliseconds (ms) and calibration in millivolts (mV) so that you will be able to measure time intervals and heights respectively. This will vary from one machine to another, so consult the machine's operating manual.
Examine each P-QRS-T complex recorded. The P wave is the first deflection in the complex and corresponds to electrical activity in the atria. The QRS complex is the second and usually most drastic deflection and reflects electrical activity within the ventricles. The T wave is the last deflection in the set and represents ventricular repolarization.
Make note of any complexes that do not have a P wave accompanying the QRS complex. Make note of any QRS complex that does not have a P wave in front of it. These are indicative of cardiac arrhythmias.
Measure the heart rate as beats per minute. Count the total number of complexes completed in a six-second period and multiply the value by 10.
Measure the P wave, the first deflection from the baseline in each heartbeat. Measure both the interval of time from start to finish and the height of the P wave.
Measure the P-R interval beginning at the start of the P wave and ending at the start of the QRS complex.
Measure the QRS interval, the time from the beginning to the end of the entire QRS complex. Measure the height of the R wave.
Measure the Q-T interval, the time from the beginning of the QRS complex to the end of the T wave.
Identify the lead that has the largest net deflection of the QRS complex in either the positive or negative direction. This should be lead ll, indicating that the largest wave of depolarization is toward the left ventricle.
Always use lead II to measure time intervals and heights, and use a set of calipers to measure time intervals and heights accurately.