When the heart is beating normally, its two lower chambers (ventricles) pump together to efficiently empty the heart and send the blood into the circulation to supply all parts of the body. In many patients with moderate to severe heart failure, the heart’s two lower chambers do not pump in synchrony. This makes it more difficult for the heart to pump blood effectively and worsens heart failure.
Recently, the Food and Drug Administration (FDA) approved a specialized pacemaker device, a biventricular pacemaker, which gives electrical signals to both heart chambers at the same time, so they will pump in synchrony again. This is called Cardiac Resynchronization Therapy (CRT) and it was studied in the MIRACLE trial (Multicenter InSync Randomized Clinical Evaluation trial).
Patients with moderate to severe heart failure receiving CRT in the MIRACLE trial:
- Improved the amount of daily activity performed without the symptoms of heart failure;
- Improved their exercise capacity as measured by the distance walked in 6 minutes;
- Improved their overall quality of life as judged by standard tests that measure this;
- Experienced favorable changes in the anatomy of their hearts that improved cardiac function;
- Reduced the number of days spent in the hospital and the total number of hospitalizations for heart failure over the time of the study;
- May experience a lengthening in their long-term survival.
The cardiac resynchronization system is comprised of a pacing device that is the size of two stacked silver dollars and three pacing wires. The procedure is performed in either the cardiac electrophysiology laboratory or in an operating room that is equipped for the implantation procedure.
The patient is given a mild relaxing sedative while the upper chest area is cleansed and shaved to avoid infection. An incision is made below the collarbone to create a small pocket for the pacemaker. The pacing leads are threaded through a large vein under the skin and down to the heart, while the physician monitors the placement of these wires using a special kind of X-ray called fluoroscopy.
After the pacing leads are connected to the pacemaker generator, the device is programmed and the incision is closed. The CRT device then delivers small electrical impulses to the different heart chambers, stimulating them to beat in synchrony. The implantation generally takes two to three hours.
The patient remains in the hospital for 1-2 days after the procedure while the heart is monitored and the pacemaker is checked for proper functioning. Doses of antibiotic are intermittently administered intravenously over a period of 24 hours. Pain medications can be given for the minor incisional discomfort that patients sometimes experience.
The incision should be monitored daily for increasing redness, swelling, warmth or drainage. The physician should be notified if dizziness, fatigue, fainting spells, chest pain, shortness of breath, swelling of the legs or arms, or prolonged hiccoughing is experienced.
The physician may adjust medications after the implantation of the pacemaker. Generally, the arm on the side of the newly implanted device should not be raised above the shoulder for about two weeks and should not be used for heavy lifting during that time period. Showering or bathing can usually be resumed 2-3 days after the procedure. Normal activities such as work, travel, exercise, sex and hobbies can be resumed gradually and with the guidance of the physician.
Restrictions and Limitations
Patients with pacemakers have very few limitations after the recovery phase. An identification card with the CRT information should be carried at all times and shown to all medical personnel caring for that patient.
The following circumstances are to be avoided:
- Close proximity to powerful magnets that are used for MRIs, electronic equipment, amusement park rides, running auto engines, large generators or power plants, or those used in junk yards.
- High intensity electrical wires, CB or Ham radio antennae
- Placing a cellular phone near the pacemaker device (the other ear is acceptable)
- Hand-held security wands
- Tight clothing over the pacemaker site
- Lithotripsy procedures
- Electric arc welding equipment
- Kilns or other induction furnaces
Other precautions may be added or deleted depending on the model and type of pacemaker implanted. Further details are found in the manufacturer’s “Patient Guide” or through the implanting physician.
Regularly scheduled visits are necessary to check the efficiency of the pacemaker and leads. Periodically, you may need an electrocardiogram and/or the pacemaker may require some programming adjustments. These are accomplished using a special computer in the doctor’s office.