When the heart beats too fast, too slow or doesn’t beat with a regular rhythm, the condition is called an arrhythmia. In some cases, the heart no longer pumps blood effectively, and as a result, the arrhythmia can be life threatening. Electrophysiology is a branch of heart medicine that looks for the causes of arrhythmia and ways to prevent it.
The heart is made up of mostly muscle. The muscle forms the walls of the four chambers of the heart. These chambers fill with blood, and when the muscle that forms the chamber walls tightens (or contracts), the blood is pushed out of the chamber. The four chambers don’t push blood all at once. Instead, they must contract in the right order to ensure that the blood is effectively collected from the rest of the body, moved through the lungs (where it picks up oxygen), then pushed back through the body. When the chambers are all working in the right order, they produce the lub-dub sound of a healthy heartbeat. Electrical signals (traveling along nerve fibers) control the order in which the chambers contract and push blood. Electrophysiologists look at these signals to diagnose heart problems and seek ways to overcome these problems.
To avoid open surgery, doctors will use small medical tools delivered to the heart by a catheter. A catheter is a thin tube that is inserted into a blood vessel through a tiny cut in the leg or arm and threaded through the bloodstream to the heart. Once in place, it acts as a tunnel, enabling the doctor to efficiently guide the tools to where they are needed.
In this procedure, the doctor inserts a catheter that runs from a small cut in the upper leg to the heart. The doctor then guides tiny electrodes (electrical connectors at the end of wires) up the catheter and into the heart. Using an X-ray machine to “see” inside the patient’s body, the doctor can precisely position the electrodes within the heart. With the electrodes in place, the doctor can test the electrical pathways (the “wiring”) within the heart to see what’s causing the unusual heartbeat. The doctor can measure the electrical current that travels through the pathways as well as injecting electricity into the pathway to see how the heart responds. The actual procedure can take as little as 20 minutes or as long as several hours.
Cardiac ablation is a procedure used to destroy cells in the heart that may be causing heart rhythm problems. Once the doctor identifies cells that are misfiring (via an electrophysiology study), he or she may choose to use high-frequency radio waves to kill these cells using technology similar to that found in a microwave oven. In the case of radiofrequency ablation, though, the energy can be precisely aimed and only destroy the misfiring cells.
In some extreme cases of cardiac arrhythmia, doctors may need to conduct open surgery to insert specialized electronic devices. There are two general types of these devices.
Implantable cardiac defibrillators
The devices are placed in people who are at high risk of sudden cardiac death. They are permanently inserted just below the collar bone and are used to “jumpstart” or jolt the heart, only when an extreme arrhythmia occurs. They are effective in returning the heart to a more regular beat.
These devices are surgically inserted into people who have heart arrhythmia that causes the heart to beat too slowly. A pacemaker works constantly to keep the heart beating at the right rate.