Final answer:
Cardiac resynchronization therapy (CRT) is a treatment for heart failure using a biventricular pacemaker or defibrillator to improve the synchronized contraction of the heart's chambers.
Step-by-step explanation:
Cardiac resynchronization therapy (CRT) is a treatment for heart failure. It involves implanting a device called a biventricular pacemaker or defibrillator to improve the synchronized contraction of the heart's chambers. CRT helps to improve symptoms such as shortness of breath, fatigue, and exercise intolerance in patients with heart failure.