Depending on several factors, including age, either a mechanical valve or one made from human or animal tissue may be implanted. The mitral valve and the aortic valve are those most commonly replaced. Those with irregular heartbeats may get assistance from many devices. A pacemaker may be implanted to help those with abnormally slow and some abnormally fast heartbeats. Pacemakers are programmable.
Defibrillators deliver a shock to restore normal rhythms.
Sometimes arrhythmias are corrected with a surgical technique called ablation, which removes tissue involved in irregular rhythms. Ablation is sometimes combined with a pacemaker. In selected patients it has achieved dramatic success. More widespread use is limited by the small number of donor organs, rejection difficulties, expense and the advanced age and complex disease status of many heart-failure patients.