Cardiac Resynchronization Therapy
CARDIAC RESYNCHRONIZATION THERAPY
Until 1999, the only treatments for congestive heart failure were medications and heart transplantation. In the late 1990s, research began using pacemaker technology to make the contractions of a weakened heart muscle more efficient. This novel approach changes the way that the heart squeezes blood out of the main pumping chamber by applying a pacemaker impulse to each side of the weakened pumping chamber. Making both sides of the heart squeeze simultaneously is similar to pushing on both sides of a beech ball at the same time to help the air go out faster. Before this time, pacemakers had only been used to speed up slow heart rates. The technology required to improve heart efficiency was built over several years of research and is now a mainstream treatment option for patients with severe heart failure.
Placement of these devices, called CRT-D, is similar to that required for an ICD implant but involves an extra pacemaker wire which goes in to a small vein in the heart called the coronary sinus and paces the outer surface of the left ventricle. The technical skills for the implantation for these devices are greater than that needed for a standard ICD or pacemaker but do not add significant risk for the patient. The total procedure time approaches one hour for these procedures but can rarely go two hours when difficult.
CRT-Ds are implanted under the skin in the upper chest. Small wires are placed inside the heart using a large vein just under the collar bone. These wires are then attached to the device which includes the battery, capacitor, and electronics. All of this material is underneath the skin.
Placement is performed at the hospital. Patients spend the night after the procdure and are almost always discharged the following day. Sedation is used during the implantation so that patients are not awake for this procedure.
The risks of a CRT-D implantation include a one in 1000 chance of death. Minor complications at the time of the procedure can include bruising or bleeding at the site of implantation or where the wires attach to the heart, and a leak of air out of the lung on the side of the implant. The only long-term risks include infection (because of the presence of a foreign body under the skin) and issues relating to recall of the device hardware or software. Most recall issues with CRT-D involve only reprogramming of the device, which is not invasive. Replacement of the defibrillator because of a recall is exceedingly rare.
Follow-up of a CRT-D requires an office visit twice per year. There are no problems using microwave ovens, cell phones, portable phones or other home electronics. The only electronic devices which present a problem are an active arc-welding machine, and the hand-held metal detector wands used at the airport. The only physical limitations after an implant are to avoid repetitive jerking motion of the arm on the same side as the implant for about 6 weeks. This limitation mainly applies to golf, tennis, overhead swimming, rowing, and bowling. After 6 weeks, there are no physical limitations to activity.
The vast majority of patients who undergo CRT-D implantation have a dramatic improvement in symptoms. Approximately 70-80% of patients have impressive changes in shortness of breath, exertional tolerance, fatigue, lightheadedness, and many are even able to decrease the amount of diuretic used. This therapy has saved many patients from the heart transplantation list and is a prime example of the power of research. For the majority of patients, this represents a truly miraculous intervention.