What is Cardiac Resynchronization Therapy?

The normal contractions of the heart chambers (atria and ventricles) are precisely synchronized and follow a strictly defined sequence. When this synchronization becomes disrupted, the amount of blood pumped with each beat is reduced, which is a cause of heart failure. A Cardiac Resynchronization Therapy (CRT) device paces the heart (using the same small electrical impulses as a standard pacemaker) both in the right and the left ventricles in order to resynchronize their contraction and attempt to increase the cardiac output.

There are two types of CRT devices:

Cardiac Resynchronization Pacemakers (CRT-P), which help resynchronize the heart contractions by pacing both ventricles simultaneously. In order to function properly, pacing leads (wires) must be placed in the right atrium, the right ventricle, and inside a cardiac vein to pace the left ventricle. All the leads can be implanted through the veins, without having to open the chest.

Cardiac Resynchronization Therapy Defibrillator (CRT-D) performs the same functions as a CRT-P, and can also deliver the therapies of an implantable cardioverter defibrillator in case ventricular tachycardia or fibrillation occurs. In patients presenting with heart failure, who are at high risk of cardiac arrest, the CRT-D can support the pumping action of the heart and protect against life-threatening arrhythmias.

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