Cardiac pacing also known as cardiac stimulation is a technique that regulates the heart rate via an artificial pacemaker. Pacemakers are devices that send electrical impulses to stimulate the heart muscles and regulate the heartbeat. These electrical impulses are delivered to the heart through thin insulated wires called pacing leads or pacemaker leads. Pacing leads play an integral role in cardiac pacing as they act as the medium to deliver electrical current from the pacemaker to the heart muscles.
Types of Pacing Leads
There are different types of pacing leads used depending on the location where they need to be attached in the heart. Some common types of pacing leads include:
– Atrial Pacing Leads: These leads are thinner than ventricular leads and are used to pace the atrium or upper chambers of the heart. Atrial leads are fixed to the right atrium.
– Ventricular Pacing Leads: Ventricular leads are thicker than atrial leads and are used for pacing the ventricles or lower chambers of the heart. They are attached either to the right ventricle or both ventricles.
– Bipolar Pacing Leads: Bipolar leads have two electrode points – tip and ring. They are commonly used as ventricular pacing leads.
– Unipolar Pacing Leads: Unipolar leads have a single electrode point at the tip and use the pacemaker housing as the second electrode point.
Lead Implantation and Functioning
The procedure to implant Cardiac Pacing Leads involves inserting thin flexible leads into the heart veins under local anesthesia via minor surgery. The leads are then attached or “fixed” to the inner heart chamber walls through the vein openings. Once implanted, the distal electrode tip is in contact with heart muscles. The proximal lead end connects to the pacemaker which is implanted under the skin in the chest area.
The pacemaker then generates low-voltage electrical impulses which travel through the lead wire and stimulate the heart muscles between heartbeats. In case of abnormal heart rhythm, the pacemaker overrides and regulates the heartbeat by delivering these impulses. Bipolar leads pace between the two electrode points while unipolar leads pace between the electrode tip and pacemaker housing. This coordinated electrical stimulation helps maintain a regular heartbeat.
Common Lead Complications
Though highly effective, pacemaker leads are also prone to certain mechanical issues and complications:
– Lead Displacement: Over time, the thin leads can move from their fixed position due to cardiac motions. This may lead to inadequate pacing.
– Lead Fracture: Repeated mechanical stresses can cause lead insulation breakdown and conductor damage leading to electrical failures.
– Venous Obstruction: Scar tissue formation around the veins can obstruct blood flow and pinch leads over years.
– Infection: Long-term implanted foreign bodies carry a small risk of device or bloodstream infections.
– Twiddler’s Syndrome: Rarely, leads can get entangled due to twisting of generator in the pocket requiring surgical untwisting.
– Paravalvular Leak: Rarely, leads can damage heart valve leaflets during insertion causing regurgitation.
Managing Lead Complications
Minor lead issues may not require any action while significant problems are managed through pacing upgrades or revisions. Techniques like lead extraction using laser/surgical sheaths help remove problematic leads. New replacement leads are then implanted to restore pacing functionality. Those at high risk of complications may opt for surgical epicardial lead placement on the heart surface. Close monitoring and timely interventions help address lead-related issues to prolong pacemaker service life.
With continued advances, pacemaker technology and leads have vastly improved over the past few decades. Modern leads are smaller, more durable and equipped with additional sensing functions. Minimally invasive extraction methods reduce surgical risks. Careful device and lead selection coupled with regular follow-ups help maximize benefits while minimizing complication risks. Cardiac pacing remains a safe and effective therapy to maintain regular heart function in patients with bradyarrhythmias and will likely see expanded applications in the future.
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it