Introduction

An electrocardiogram (ECG or EKG) is a graphical recording of the electrical events occurring within the heart. In a healthy heart there is a natural pacemaker in the right atrium (the sinoatrial node) which initiates an electrical sequence. This impulse then passes down natural conduction pathways between the atria to the atrioventricular node and from there to both ventricles. The natural conduction pathways facilitate orderly spread of the impulse and coordinated contraction of first the atria and then the ventricles. The electrical journey creates unique deflections in the EKG that tell a story about heart function and health. 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. A positive deflection in an EKG tracing represents electrical activity moving toward the active lead (the green lead in this experiment).

Objectives

In this experiment, you will

  • Obtain graphical representation of the electrical activity of the heart over a period of time.
  • Learn to recognize the different wave forms seen in an EKG, and associate these wave forms with activity of the heart.
  • Determine the heart rate by determining the rate of individual wave forms in the EKG.
  • Compare wave forms generated by alternate EKG lead placements.