Cardiac pacing is a medical intervention that uses electrical stimulation to regulate the heart’s rhythm when its natural electrical system is not functioning correctly. The heart’s own electrical impulses control the timing of muscle contractions, but a failure in this system can cause the heart to beat too slowly or irregularly. A pacemaker, a small implanted electronic device, delivers low-energy electrical pulses to the heart muscle to maintain a proper rate, improving quality of life.
Why Pacing is Necessary
The need for cardiac pacing arises when the heart’s intrinsic electrical signals are too slow or are blocked, a condition often referred to as bradycardia. The sinoatrial (SA) node, the heart’s natural pacemaker, can malfunction due to age or disease, leading to a condition called Sick Sinus Syndrome (SSS). SSS can cause periods of abnormally slow heart rates, fast rates, or pauses in the heart’s rhythm, which may result in fatigue, dizziness, or fainting episodes.
Another common indication for a pacemaker is Atrioventricular (AV) block, often called heart block, where the electrical signal transmission between the upper chambers (atria) and lower chambers (ventricles) is delayed or completely interrupted. This disruption means the ventricles do not receive the signal to contract at the appropriate time. Second-degree Mobitz II and third-degree AV blocks are specifically known to require permanent pacing intervention. A pacemaker ensures that the heart maintains a sufficient beat rate to deliver adequate blood and oxygen to the brain and other organs.
How a Pacemaker Works
A traditional pacemaker consists of two main components that work together to monitor and regulate the heart’s electrical activity. The first component is the pulse generator, a small metal case containing a battery and a miniature computer circuit. This computer controls the timing and rate of the electrical signals delivered to the heart.
The second component involves the leads, which are thin, insulated wires with electrodes at the tip that connect the pulse generator to the heart muscle. These leads perform a dual function: they sense the heart’s natural electrical activity and deliver the corrective electrical impulses when necessary. The pacemaker operates on demand, meaning it monitors the intrinsic rhythm and only sends a pulse if the heart rate drops below a preset minimum or if a beat is missed.
Pacemakers are categorized based on the number of heart chambers they pace and sense. A single-chamber pacemaker uses one lead, typically in the right ventricle or atrium. A dual-chamber device uses two leads, one in the right atrium and one in the right ventricle, to mimic the heart’s natural two-step contraction sequence more closely. A biventricular pacemaker, also known as a Cardiac Resynchronization Therapy (CRT) device, uses three leads to stimulate both lower chambers to improve the pumping efficiency for people with heart failure. Leadless pacemakers represent a newer technology, where the pulse generator and electrode are combined into a single, small capsule placed directly inside the heart’s right ventricle, eliminating the need for traditional wires.
The Implantation Procedure
The implantation of a permanent pacemaker is typically a minor surgical procedure performed under local anesthesia with intravenous sedation. The procedure usually takes between one and two hours to complete. The surgeon makes a small incision, approximately two inches long, usually in the upper chest just below the collarbone.
The pacing leads are inserted into a large vein in the shoulder area and carefully guided through the vein into the appropriate chambers of the heart. Throughout this process, the surgeon uses real-time X-ray imaging, called fluoroscopy, to accurately position the electrodes within the heart. Once the leads are secured to the heart muscle, they are connected to the pulse generator, which is then placed in a small pocket created just beneath the skin in the chest area.
After the generator is securely placed, the system is tested to ensure it is sensing and pacing effectively according to the required settings. The incision is closed with stitches, and patients are monitored in the hospital, often requiring an overnight stay. Immediately following the procedure, the arm on the side of the implant may be immobilized briefly to prevent movement that could dislodge the newly placed leads.
Adjusting to Life with a Pacemaker
Living with a pacemaker involves a routine of follow-up care to ensure the device is functioning optimally. Patients require regular checkups with their cardiologist, often every three to six months, to monitor the pacemaker’s settings, battery life, and stored data. Many modern pacemakers allow for remote monitoring, where the device sends data to the clinic wirelessly, reducing the frequency of in-person visits.
Activity guidelines after implantation focus on protecting the device and the leads during the initial recovery phase. While most normal activities can be resumed quickly, contact sports and vigorous activities involving the arm on the side of the implant are limited for a few weeks to allow the leads to fully secure within the heart tissue. Patients are encouraged to carry a pacemaker identification card that contains important device information for emergencies and security checks.
The risk of Electromagnetic Interference (EMI) is a practical consideration, though modern pacemakers are well-shielded. Electronic devices with strong magnetic fields, like cell phones, should be kept at least six inches away from the pacemaker site. It is safest to hold a cell phone to the ear opposite the implant or use speaker mode. While common household appliances like microwaves generally pose little risk, medical procedures such as Magnetic Resonance Imaging (MRI) require special consideration. Many newer pacemakers are MRI-compatible, but the device must be checked and often temporarily reprogrammed before and after the scan to ensure safety.