Cardiac Resynchronization Therapy (CRT) is an advanced treatment for individuals living with heart failure. This technology utilizes a specialized pacemaker, often referred to as a biventricular pacemaker, to help the heart’s lower chambers pump blood more effectively. The goal of CRT is to restore a coordinated and efficient contraction pattern to a heart that has become weakened. By doing so, it aims to reduce heart failure symptoms, improve the patient’s capacity for physical activity, and enhance overall survival.
Understanding Cardiac Dyssynchrony
The necessity for a CRT device stems from cardiac dyssynchrony, a condition found in some heart failure patients. In a healthy heart, electrical signals travel uniformly, causing the left and right ventricles to contract simultaneously, efficiently propelling blood. In dyssynchrony, this signaling is delayed, often affecting the left ventricle and causing the chambers to contract out of sync. This delay is identified on an electrocardiogram (ECG) as a wide QRS complex, indicating the ventricles take too long to electrically activate. This irregular signal creates a mechanically inefficient pump, forcing the heart to work harder while moving less blood. Correcting this electrical conduction delay is the target of resynchronization therapy for patients with moderate to severe heart failure.
The Mechanism of Resynchronization
The CRT device corrects mechanical inefficiency using biventricular pacing, a sophisticated method of electrical stimulation. Unlike a traditional pacemaker that typically uses one or two wires to regulate a slow heart rate, a CRT system employs a three-lead strategy to coordinate the chambers. These thin, insulated wires, called leads, are placed in three locations: the right atrium, the right ventricle, and the left ventricle.
The left ventricular lead is guided through the coronary sinus, a vein wrapping around the back of the heart, allowing the electrode to stimulate the left ventricle from its outer surface. This setup allows the device’s generator, or battery pack, to deliver simultaneous electrical impulses to both ventricles. By stimulating both major pumping chambers instantly, the device overrides the natural, delayed electrical pathway. This simultaneous contraction restores the heart’s mechanical synchronization, improving blood output.
The Implantation Procedure
Implanting a CRT device is a minor surgical procedure, typically performed by an electrophysiologist in a hospital setting. Patients receive local anesthesia to numb the incision site, along with intravenous sedation to help them remain relaxed and comfortable. The procedure usually takes between two and three hours. The physician makes a small incision, usually below the collarbone, and creates a pocket beneath the skin or muscle for the generator.
The three leads are carefully guided through a major vein leading to the heart. Specialized X-ray imaging, called fluoroscopy, is used constantly to ensure the leads are precisely positioned within the right atrium, the right ventricle, and the coronary sinus for the left ventricle. Once the leads are secured and tested to confirm they are functioning correctly, they are connected to the generator. The generator is then placed into the pocket and the incision is closed with sutures.
Patients usually spend one night in the hospital for observation and optimal device programming before discharge. Immediate post-operative care involves keeping the incision clean and dry. For a short period, patients must limit heavy lifting or extensive movement of the arm on the side of the implant. This restriction is crucial to allow the leads time to secure themselves firmly to the heart tissue.
Living with a CRT Device
After the initial recovery period, living with a CRT device requires certain long-term management practices centered on monitoring and safety. The generator’s battery life is finite, typically lasting between five and ten years, depending on the model and how often the device is required to pace the heart. Regular follow-up appointments, often scheduled every six months, are necessary to check the battery status and ensure optimal device programming.
Many modern CRT devices support remote monitoring, where a small home unit wirelessly transmits data to the clinic, allowing physicians to detect potential issues between visits. Patients should carry an identification card detailing their device information, especially when traveling. While most household electronics are safe, items with strong magnetic fields, such as certain cell phones or power tools, should be kept at least six inches away to prevent temporary interference. When passing through security screenings, such as at an airport, patients should inform personnel about their implant to request a hand search instead of being scanned with a hand-held metal detector wand.