This procedure is indicated for patients who have symptoms of heart failure and abnormal contraction of heart. These are special type of implantable pacemakers or defibrillators that have an extra lead implanted through a vein in the back of the heart. This extra lead will pace the left side of the heart to synchronize right and left side of the heart. This can lead to significant improvement in pumping capacity of heart and improvement of symptoms related to heart failure like shortness of breath, easy fatigability, swelling of legs and fullness in stomach.