An EKG (electrocardiogram) is a painless medical procedure that monitors the movements of cardiac muscles. EKG's are used to detect abnormalities in heart rhythm that may be indicators of serious defects in the heart. Electrodes are attached to the patient where the heart rhythms can be read, usually the chest area. Not too long ago, my class experimented with EKG's. I put 3 small electrodes on my arms. one on each wrist and another on my upper right arm. The placement of the electrodes resulted in how the graph looked on the computer I was monitoring on. If I switched two of the electrodes' places, the graph looked different. For example, when I switched the places of the electrodes on my left wrist and right upper arm, the graph produced on the computer was the inverse of when they were in the normal positions. On the graph, my heart rhythms looked somewhat like this:
On this EKG graph, the P wave represents the depolarization of both atria. From the P wave to the Q wave, which may not always be present in a normal EKG, is the PR interval, the time from atrial depolarization to the start of ventricular depolarization. The Q waves are the first downward deflections before the R waves, the first upward deflections. After the S waves represent the time left for ventricular depolarization. The QRS complex is the electrical wave that signals the depolarizations of myocardial cells of the ventricles. The T wave represents the re-polarization of the ventricles. The ST segment is a period of diastole from the end of systole to re-polarization in the ventricles.
Getting this data from the EKG sensor was much easier than understanding just what it all meant.
