Cardiac Resynchronization Therapy – A Treatment Option for Congestive Heart Failure
The American Heart Association reports that nearly 5 million Americans are living with congestive heart failure, with approximately 550,000 new cases diagnosed each year.
Described as a chronic, progressive condition that typically worsens with time, it can affect either the left or right side of the heart or both.
That diagnosis—heart failure—may sound confusing. How is one able to remain alive while in heart failure? Heart failure does not mean that the heart has completely stopped working and is no longer a functioning organ.
Rather, as cardiologist Dr. Chinmay Patel with PinnacleHealth CardioVascular Institute explains, “In patients with congestive heart failure, the pumping function of the heart is reduced.”
When the heart’s pumping function becomes inefficient and no longer works at full power, the heart’s rhythm or beats become irregular. This defective pumping function subsequently prevents the body from receiving its adequate supply of blood and oxygen, which, if left untreated, will gradually diminish a person’s quality of life.
Patel says symptoms that may result from the heart’s inability to pump sufficient blood to satisfy the body’s need for oxygen can include shortness of breath, dizziness, leg swelling, fatigue, or lack of energy and the inability to walk long distances.
However, he adds that, “Cardiac resynchronization therapy is a treatment that can help alleviate some of these symptoms.”
Although not a cure, CRT, which is often combined with other treatments for optimal results, is an option worthy of consideration if a patient diagnosed with congestive heart failure meets the suitability criteria.
When a heart is normal and healthy, Patel says its conduction system keeps the blood-pumping function synchronized by a coordinated spread of electrical impulses that use specialized electrical pathways, originating from the heart muscle.
“This coordinated spread of electrical impulses,” he says, is what “leads to the synchronous contraction of the heart walls, leading to efficient pumping of the blood.”
Certain heart failure patients have a defective conduction system, resulting in what Patel explains as “dyssynchronous spread of electrical impulses in the heart walls and ineffective pumping of the blood.”
This anomaly in the conduction system can be identified with an EKG. He says if the EKG indicates that the patient is in congestive heart failure with reduced pump function (also known as ejection fraction), accompanied by a cardiac conduction/electrical system abnormality, then he/she may be a candidate for cardiac resynchronization therapy.
“CRT,” says Patel, “could be offered as part of a pacemaker implantation or with a defibrillator implantation.”
So how does this half-dollar-sized device, which is usually implanted just below the collarbone, help “sync” or re-coordinate the heart’s pumping action?
“The two main components of pacemakers,” he says, “are a generator (that houses the battery and circuit of the pacemaker) and electrical wires, also called leads, which are connected to the heart.”
Depending on the type of pacemaker used, there can be one to three leads.
“A standard pacemaker,” says Patel, “is programmed to prevent low heartbeats, providing electrical impulses to the heart in case natural electricity of the heart fails.”
The difference between standard pacemakers and pacemakers that offer cardiac resynchronization therapy is in the amount of leads they require. He explains that the CRT device “has three leads that stimulate the wall of the heart in synchronous fashion to optimize the pump function of the heart.”
As with many treatment options, there are also risks to consider with CRT. Pacemaker implantation is categorized as an invasive procedure, and because of that Patel says there is a 1-2 percent risk of complication. These possible complications include damage to the lung, cardiac chamber perforation, fluid around the heart, lead dislodgement, and risk of infection.
He adds that due to the number of pacemaker implants performed today, it has “become one of the low-risk procedures and can be accomplished without any complications in the majority of cases.”
Depending on the type of pacemaker implant, the procedure itself can last from 45 minutes to two hours, with “patients typically kept in the hospital overnight,” says Patel.
Patients can expect moderate pain or discomfort, lasting anywhere from 24 hours to a week. Those in recovery are advised to “limit lifting weights and restrict specific movement of the side where the pacemaker was implanted for four to six weeks, and after that, there are no specific restrictions,” he says.
Many patients who have undergone CRT, also called biventricular pacing, report improved walking distance and an increase in energy, along with a reduction in shortness of breath. As a result of CRT, numerous patients have been able to reclaim their independence with an enhanced quality of life, thanks to this technology that provides additional support to the heart.
Patel says that CRT has also been shown to reduce heart failure hospitalizations, in addition to helping patients live longer.
As far as future developments in pacemaker technology, Patel says that as “the science of the pacing of the heart evolves, the use of leadless pacemakers is likely to expand.”
He says that’s because the lead is generally considered to be the weak link in the circuit.
“Leadless pacemakers,” says Patel, “eliminate the current required lead and are implanted directly inside the heart.”
To date, he says a leadless pacemaker has been manufactured and is approved by the FDA. So far, it’s indicated for use only in patients who require a single-chamber pacemaker. BW