CRT uses uses a specialized pacemaker to re-coordinate the action of the right and left ventricles in patients with heart failure.
In approximately 30% of patients with heart failure, an abnormality in the heart's electrical conducting system (called an "intraventricular conduction delay" or bundle branch block) causes the two ventricles to beat in an asynchronous fashion. That is, instead of beating simultaneously, the two ventricles beat slightly out of phase. This asynchrony greatly reduces the efficiency of the ventricles in patients with heart failure, whose hearts are already damaged.
CRT re-coordinates the beating of the two ventricles by pacing both ventricles simultaneously. This differs from typical pacemakers, which pace only the right ventricle. When the work of the two ventricles is coordinated, the heart's efficiency increases, and the amount of work it takes for the heart to pump blood is reduced.
Studies with CRT have demonstrated its ability to improve the symptoms, the exercise capacity, and the feeling of well-being of many patients with moderate to severe heart failure. Studies have also shown that CRT can improve both the anatomy and function of the heart - tending to reduce the size of the dilated left ventricle, and therefore improving the left ventricular ejection fraction. Perhaps most importantly, CRT can improve the survival of patients with heart failure.
Should Your Doctor Consider CRT?If you have heart failure that is limiting your ability to function normally, and you are already receiving aggressive medical therapy for heart failure, you should discuss the possibility of CRT with your doctor. Your doctor will help you determine whether you are a good candidate for this form of therapy, and whether CRT is right for you.
Burkhardt, JD, Wilkoff, BL. Interventional electrophysiology and cardiac resynchronization therapy: delivering electrical therapies for heart failure. Circulation 2007; 115:2208.
Cleland, JG, Daubert, JC, Erdmann, E, et al. The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med 2005; 352:1539.