The QRS represents the depolarization or contraction of the lower ventricles. The duration of the QRS is indicative of ventricular disease in general, with a wider QRS representative of slowed ventricular conduction. The p-wave represents the atrial depolarization, or contraction phase, when the sinus rhythm beat electrically captures the left and right atria. The continuous repetitive unit of the cardiac cycle is the “ P-QRS-T” waveform. The waveforms depicted in an EKG can be divided into time segments measuring particular phases of the cardiac cycle or contraction. The p-wave represents atrial activation, the QRS represents ventricular contraction, and the t-wave represents ventricular electrical recovery. The components of an EKG recording during a single cardiac cycle (single heart beat) is shown above. It is recorded as an output of waveforms that your physician can print onto paper or record on the monitor.įigure 1. The resultant electrocardiogram represents a mesh of cardiac electrical activity from the atrium and ventricles, dependent on the direction and magnitude of the electrical depolarization as it spreads throughout the heart. These electrode wires are connected to the EKG machine with recordings from 12 different locations on the surface of the body, the so-called 12-lead EKG. determine normal pacemaker or ICD functioningĪ standard surface EKG is recorded using electrodes, or sticky patches, placed on the body surface, typically over the chest and the extremities.investigate any evidence of coronary artery blockages.determine if there is evidence of a myocardial infarction, or “heart attack”.investigate a history of syncope or palpitations.pursue evidence of a high-risk arrhythmia syndrome, such as Long-QT and Brugada Syndrome.Your physician may order an EKG for the following reasons:

Where the heart leads