Stanford Cardiac Arrhythmia Service

Cardiac Resynchronization Therapy

What is Cardiac Resynchronization Therapy?
In some patients with heart failure, the two lower chambers of the heart don't beat at the same time, making the heart less efficient in its function. This can lead to worsening of shortness of breath and decreased ability of exertion.

Cardiac resynchronization therapy is an innovative procedure that coordinates or "resynchronizes" the heart, so both chambers beat at the same time. 

The Cardiac Resynchronization Therapy Device
Cardiac resynchronization therapy is delivered using a specialized device that also serves as a pacemaker or defibrillator that is implanted under the skin of the chest. The cardiac resynchronization therapy device delivers small electrical impulses that synchronize the contractions of the lower chambers (ventricles) of the heart.

Traditional pacemakers have one or two electrode wires (called leads) that carry electrical impulses from the device to the heart. One may deliver impulses to the right atrium (upper heart chamber); the other ,may deliver impulses to the right ventricle.

A cardiac resynchronization therapy device has an additional wire or lead that’s positioned in a vein on the surface of the left ventricle. With these wires or leads, the device can stimulate both the left and the right ventricles at the same time. The result is a more coordinated and effective heart beat. This is sometimes called “bi-ventricular pacing.”

Who Can Benefit from Cardiac Resynchronization Therapy?
Cardiac resynchronization therapy is for those who have:

How is the Cardiac Resynchronization Therapy Device Implanted?
The implantation of a cardiac resynchronization therapy device is a  procedure performed in the cardiac catheterization laboratory.

Your upper chest will be scrubbed and shaved (if needed) and you will be covered with sterile sheets. You will receive medication through an IV to help you relax. A local anesthetic will be applied at the site of the implantation.  After the area is numb, access will be obtained through the vein under the collar bone.    Wires or leads will be inserted into this vein and advanced to  the heart's chambers using fluoroscopy (x-ray monitors). The wire or lead to be used to pace the left ventricle will be advanced into the vein on the outside of the left ventricle.   In about 10% of cases, it is not possible to place the wire or lead into the vein to pace the left ventricle, usually because the branches of the veins are too small.     In about 5 to 10% of cases, the wire or lead may need to be repositioned because it has moved or paces the diaphragm, causing the chest to twitch.  Once the wires are in position, your physician will make a two to three inch incision in your skin, creating a small "pocket." The wires or leads will be connected to the cardiac resynchronization therapy device, which will then be placed into the pocket. Finally, the incision will be stitched up.


There is about a 10% inability to place the lead that paces the left ventricle since the veins that drain the left ventricle vary from person to person and in some patients they are not suitable for a lead.  If this is not successful, there is an option of having a heart surgeon place a lead on the outside of the heart making an incision in the chest but this will not be done at the same sitting and will require a separate procedure and will decided upon after this procedure. 

There is about a 2-3% risk of stroke, heart attack, death, damage to the heart or lungs requiring surgery, including puncturing the heart.  There is a risk of bleeding and bruising, damage to the artery, nerves, and veins requiring surgery or transfusions, blood clots and swelling and infection.   There is about a 5-10% chance of the lead dislodging or causing diaphragmatic stimulation resulting in twitching on the side, usually requiring reoperation.  There is a remote risk of kidney failure requiring dialysis. 

Not all patients improve symptomatically as the result of biventricular pacing. About one third of patients do not improve or worsen.

What Happens After the Cardiac Resynchronization Therapy Device is Implanted?
You will remain in the hospital overnight after the cardiac resynchronization therapy procedure. A nurse will check your blood pressure, pulse and incision. You will not be allowed to move the arm on the side of the implant. This gives the wires time to stabilize in your vein and heart.

The incision around the pacemaker will be sore. You’ll receive medication to make you more comfortable.

Most patients with Cardiac Resynchronization Therapy will have adjustments made to the settings to optimize the heart function. Sometimes this is done using an echocardiogram or ultrasound of the heart to adjust the settings to improve the heart’s efficiency.

The Stanford Cardiac Arrhythmia Service provides special expertise in the implantation of Cardiac Resynchronization Therapy devices and state-of-the-art techniques in the follow-up and adjustment of these devices.  Some patients who have not had previously successful Cardiac Resynchronization Therapy systems may receive evaluation at Stanford to see if positioning or repositioning of the left ventricular lead is desirable.

What Happens After I Leave the Hospital?
You must remember several things in caring for yourself after you leave the hospital. Your doctor may prescribe antibiotics, which you’ll take for several days. You’ll need to check your temperature twice a day and change the dressing over the cardiac resynchronization therapy device daily. You should inspect the incision for redness, swelling or drainage and replace the dressing with a clean, dry bandage. You should not remove the steri-strips over the incision or cleanse or rub the incision. If you develop redness, swelling, drainage, increased tenderness or an elevated temperature, please notify us immediately (650-723-7111).
After the third day, you may shower. It’s okay for the incision to get wet at that time, but don’t scrub the area, and keep the force of the water from spraying directly on the incision. The steri-strips will start to loosen and will probably come off seven to 10 days after surgery.

You should have a follow-up appointment with your physician within seven to 10 days. Do not lift or move the arm on the side of the cardiac resynchronization therapy device above the level of your shoulder for four weeks. Once you see your physician, he or she will provide guidelines on increasing your activity.

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