Difference Between Pacemaker & Cardiac Resynchronization Therapy

August 30, 2022 | 3 minutes read time

When it comes to heart disease, it is important to have an understanding of the difference between a pacemaker and cardiac resynchronization therapy (CRT). Both pacemakers and CRT devices are designed to help your heart beat normally.

Pacemaker and Cardiac Resynchronization Therapy are sometimes used interchangeably. However, these two treatments are different and have different purposes. In this blog post, Dr. Vanita clears the difference between these two types of treatments.

What is a Pacemaker?

It is a small medical device that is about the size of a pocket watch. The pacemaker comprises three parts:

● a pulse generator: it contains the battery, a small computer, and electronic circuitry required to send small electrical impulses to the heart.

● one or more leads: these are insulated wires that carry the impulses to the heart’s chambers through a large vein.

● an electrode on each lead: this is what touches your heart wall. Electrodes are responsible for delivering the impulses.

Depending on your medical condition, the leads can be connected to your ventricle (lower chamber) or atrium (upper chamber), or both. When the patient’s heart rate reduces below the lower limit of their pacemaker, the device sends an electrical signal to correct it, the best pacemaker doctor in India explains.

There is a second type of pacemaker that does not have leads at all nor the requirement for a surgical pocket for pulse generator. The leadless pacemaker, as it’s called, is 90% smaller than a regular pacemaker and is implanted directly into the ventricle. It eliminates the possibility of several complications that can occur with a regular pacemaker, such as lead fracture, lead dislodgement, pocket infections, etc.

What is a CRT Device?

In a healthy heart, both ventricles pump in unison, the top pacemaker doctor in India explains. But in some patients with heart failure, there is a mismatch in that coordination. This is known as ventricular dyssynchrony.  

For such patients, a special type of pacemaker is used to pace both ventricles so that they beat simultaneously, at the exact time. Such a device is called a biventricular pacemaker or cardiac resynchronization therapy device.

It has a pulse generator and three leads. One lead is connected to the right ventricle. The second is implanted into the coronary sinus vein. This is to pace the left ventricle. A third lead is sometimes connected to the right atrium to maintain AV synchrony, according to the top pacemaker doctor in India.

This allows your heart to supply oxygen-rich blood throughout the body, Dr. Vanita explains.

Types of CRT Devices

There are two types of CRT devices. One is what we just discussed, a CRT pacemaker or CRT-P. The second type is known as cardiac resynchronization therapy defibrillator (CRT-D).

This device is implanted in patients who are at an elevated risk for sudden cardiac death. It performs the function of a biventricular pacemaker, and can also deliver a shock (defibrillation) when heartbeats are dangerously fast or during ventricular fibrillation (heart twitching or quivering instead of squeezing or expanding).

Both scenarios can be fatal for patients.

And that’s how a CRT device is different from a pacemaker!

Consult Dr. Vanita

A distinguished cardiologist and electrophysiologist in India, Dr. Vanita has treated arrhythmia patients for decades. She is currently a senior consultant cardiac electrophysiologist and interventional cardiologist at Apollo Hospital, Delhi.