Brief Answer:
please see below

Detailed Answer:
Dear Sir
1. Cardiac resynchronization therapy (CRT) is given to individuals who have enlarge heart (left ventricle) with decreased pumping (low ejection fraction) and Left bundle branch block (LBBB) in ECG. The pumping in these patients tend to improve with CRT. In a given individual it is not feasible to predict exact improvement but it can range from 5% to 100% of existing pumping. It is a kind of pacemaker device with wires. It is inserted beneath skin on the upper chest wall and the attached wires go to the heart through the blood vessels (which are not visible outside).
2. Implantable defibrillator is a device which looks similar to a pacemaker and is inserted as described above. It is inserted to prevent fatal rhythm disorders in susceptible individuals. They prevent the death by giving shock at time of rhythm disorder (ventricular tachycardia & fibrillation.)
3. Both these can be inserted in a single device (CRT-D). However benefit in patients with previous heart attack and those with atrial fibrillation is lesser for CRT as compared to others. Since success rate is different for different people, inquire it in detail for your case before getting it done.
4. This procedure is available in nearly all big cardiac centers in all major cities of XXXXXXX XXXXXXX Safdarjung Hospital, GB pant hospital, RML hospital in XXXXXXX provide this facility. It is available in major private hospitals too. Cost of procedure depends upon hospitals, if it is government hospital it will cost around 4 lakhs and in private hospitals it will be 9 lakhs. Here I have mentioned government hospitals in XXXXXXX since I can see your location as XXXXXXX
Sincerely
Sukhvinder

---