CRT

Cardiac resynchronization therapy

Cardiac resynchronization therapy is a procedure to implant a device in the chest to make the heart's chambers squeeze (contract) in a more organized and efficient way.

Cardiac resynchronization therapy (CRT) uses a device called a biventricular pacemaker — also called a cardiac resynchronization device — that sends electrical signals to both lower chambers of the heart (right and left ventricles). The signals trigger the ventricles to contract in a more coordinated way, which improves the pumping of blood out of the heart.

Sometimes the device also contains an implantable cardioverter-defibrillator (ICD), which can deliver an electrical shock to reset the heartbeat if the heart rhythm becomes dangerously irregular.

Why it's done

Cardiac resynchronization therapy is a treatment for heart failure in people whose lower heart chambers (ventricles) don't contract in a coordinated fashion. It's frequently used for people who have heart failure and a condition called left bundle branch block or for people who are likely to require cardiac pacing due to low heart rates.

If you have heart failure, your heart muscle is weakened and may not be able to pump out enough blood to support your body. This can be worsened if your heart's chambers aren't in sync with each other.

Cardiac resynchronization therapy may reduce symptoms of heart failure and lower the risk of heart failure complications, including death.

Cardiac resynchronization therapy devices include:

• Cardiac resynchronization therapy with a pacemaker (CRT-P). The device used for cardiac resynchronization therapy has three leads that connect the pacemaker to the right upper chamber of the heart (right atria) and both lower chambers (ventricles).

• Cardiac resynchronization therapy with a pacemaker and an ICD (CRT-D). This device may be recommended for people with heart failure who also have a risk of sudden cardiac death. It can detect dangerous heart rhythms and deliver a stronger shock of energy than a pacemaker can deliver. This shock can reset the heartbeat.