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How is a CRT Device implanted?
Whether the CRT device is placed in the chest or abdominal wall, the skin needs to be incised. Some doctors prefer to place the CRT device immediately below the skin, while others prefer to place it under a muscle. In either case, a "pocket" is created to bury the device, most often under the left collar bone.
First, 2 leads are usually introduced through a vein, and placed in the right atrium and right ventricle, respectively. Their position is verified by x-ray, before testing to ensure that they are in close contact with the heart muscle.
The CRT-P and CRT-D procedures require the implantation of an additional lead to pace the left ventricle, while the leads of standard pacemakers and ICDs are limited to the right side of the heart. The additional lead is placed inside a vein on the surface of the left ventricle through a guiding catheter (thin tube) advanced into the right atrium like a pacemaker lead.
From the right atrium, the lead enters a large vein, called the coronary sinus. Then, it is advanced to its final position on the left ventricle. An x-ray picture of the veins around the heart is often taken during the procedure to help guide the lead placement. This requires the injection of liquid contrast material inside the coronary sinus. In most, but not all cases there is a suitable vein for the placement of the left-sided lead.
The CRT device implantation procedure is 
usually performed under general anesthesia, although deep sedation might suffice. Your doctor will discuss this with you. The device is implanted in the chest wall or in the abdominal wall, depending on the model chosen. This decision also depends on:
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the patient’s dimensions, shape, age and heart size
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whether prior chest surgery has been performed
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routine activities and lifestyle
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which method is safest in individual circumstances
The leads are connected to the device, which is then placed in the pocket.
At the end of the procedure, the guiding catheter is removed and the left-sided lead is left in place and tested. An ultrasound study of the heart (echocardiogram) might be required to help find the pacing site that provides the most effective resynchronization by the CRT system. This test requires only external monitoring and is pain-free.
