Doctors and other trained personnel can look at an EKG tracing and see evidence for disorders of the heart such as abnormal slowing, speeding, irregular rhythms, injury to muscle tissue (angina), and death of muscle tissue (myocardial infarction). By looking at several beats you can also calculate the rate for each component. The T wave results from ventricular repolarization, which is a recovery of the ventricular muscle tissue to its resting state. Ventricular activation is represented by the QRS complex. The P wave represents the start of the electrical journey as the impulse spreads from the sinoatrial node downward from the atria through the atrioventricular node and to the ventricles. Five components of a single beat are traditionally recognized and labeled P, Q, R, S, and T.

A positive deflection in an EKG tracing represents electrical activity moving toward the active lead (the green lead in this experiment). Even more information is obtained by looking at the story from different angles, which is accomplished by placing electrodes in various positions on the chest and extremities.

The electrical journey creates unique deflections in the EKG that tell a story about heart function and health (Figure 1). The natural conduction pathways facilitate orderly spread of the impulse and coordinated contraction of first the atria and then the ventricles. This impulse then passes down natural conduction pathways between the atria to the atrioventricular node and from there to both ventricles. In a healthy heart there is a natural pacemaker in the right atrium (the sinoatrial node) which initiates an electrical sequence. Analyzing the Heart with EKG An electrocardiogram (ECG or EKG) is a graphical recording of the electrical events occurring within the heart.

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