In 1895, Willem Einthoven described the waves recorded from his invention, the string galvanometer. His PQRST diagram is remarkably similar to the P, QRS, and T waves currently used daily by cardiologists everywhere for interpretation of a standard electrocardiogram (ECG).
Extending throughout the human body is a complex circulatory system comprised of veins and arteries, which circulates blood in order to replenish tissues and vital organs with oxygen and nutrients.
The cardiac action potential is the recording of the changes of electrical potential over time recorded from inside a cardiac myocyte (heart muscle cell). The action potential is due to the flow of electrolytes through the plasma membrane changing the voltage across the cell.
The electrocardiogram, or ECG, is a graphic representation of the electrical activity from the heart. The standard 12-lead ECG is a recording of electrodes placed on all four limbs and across the precordium (or chest) of the patient.
Basic life support (BLS) and advanced cardiac life support (ACLS) are required training for personnel working in the electrophysiology laboratory. According to the American Heart Association, only 30 percent of the U.S. population is sufficiently trained to perform BLS. Why is this important? It is estimated that 88 percent of cardiac arrests occur in the victim’s home.
The electrophysiology laboratory is a unique place for the diagnosis and treatment of cardiac arrhythmias. In general, it is an invasive laboratory very similar to the cardiac catheterization laboratory.
Radiation protection in electrophysiology is essential to all patients and personnel in order to minimize the cumulative effects to the bone marrow and other radiation-sensitive tissue as well as the possible risk of cancer.
In the beginning of an electrophysiology study, it is important to gain venous and/or arterial access. This is essentially placing an intravenous catheter (an introducer sheath) into a vein and/or artery. For electrophysiology procedures, it is not uncommon to place three introducer sheaths into a single femoral vein.
One of the critical components of an electrophysiology study is the evaluation of conduction. Concepts presented in this chapter are in the order in which they are usually evaluated during a routine electrophysiology study. The first concept, conduction, can be assessed by pacing a proximal structure and assessing the delivery of the electrical impulse to a more distal structure.
Arrhythmias can be mechanistically separated into those due to abnormal impulse generation and those due to abnormal impulse conduction. The mechanisms of arrhythmias may be broken down into three categories: reentry, automaticity, and triggered arrhythmias.