Conduction System Pacing (CSP), often called CV Pace, is an advancement in treating slow heart rhythms. This approach directly engages the heart’s intrinsic electrical wiring system. By stimulating the native conduction pathways, CV Pace aims to restore the heart’s natural, synchronized pumping action. This technique addresses limitations associated with conventional pacemakers, offering a more physiological solution for patients requiring chronic electrical support.
The Heart’s Natural Pacing System
The heart’s rhythm originates in a specialized cluster of cells known as the sinoatrial (SA) node, often called the natural pacemaker. The electrical impulse travels from the SA node through the atria to the atrioventricular (AV) node, which acts as a gatekeeper, momentarily delaying the signal. This brief delay is essential as it allows the atria to fully contract and fill the ventricles before the main pumping chambers are activated.
The signal then moves rapidly into the Bundle of His, a short tract of specialized tissue located in the septum, the wall separating the ventricles. From there, the impulse splits into the left and right bundle branches, which fan out into a network of Purkinje fibers throughout the ventricular muscle. This highly organized pathway ensures both ventricles contract nearly simultaneously and efficiently, which is the hallmark of a healthy heartbeat. Disruption anywhere along this rapid electrical superhighway can lead to an unsynchronized, less effective contraction.
How Conduction System Pacing Works
Conduction System Pacing is designed to mimic this natural electrical sequence by placing a specialized lead directly into or near the heart’s native wiring. There are two primary techniques used in this approach: His-Bundle Pacing (HBP) and Left Bundle Branch Area Pacing (LBBAP). In HBP, the pacing lead tip is secured into the interventricular septum to capture the Bundle of His, the common pathway immediately after the AV node. Successfully capturing this point restores the electrical signal to both the left and right bundle branches, often correcting existing conduction blocks.
Left Bundle Branch Area Pacing (LBBAP), the newer and increasingly common technique, involves advancing the lead deeper into the septum to directly stimulate the left bundle branch or its immediate fascicles. This method offers more stable electrical performance and lower capture thresholds compared to HBP. Both HBP and LBBAP aim to achieve physiological activation, resulting in a narrow QRS complex on an electrocardiogram. This synchronized spread of electricity ensures the ventricles contract in a coordinated fashion, much like a healthy heart.
The Clinical Advantage Over Conventional Pacing
The superiority of CV Pace stems from its ability to prevent the electrical and mechanical inefficiency caused by traditional right ventricular (RV) pacing. Conventional pacemakers typically place the lead in the apex of the right ventricle, initiating ventricular contraction from a single, non-physiological point. This results in ventricular dyssynchrony, where the electrical signal spreads slowly across the muscle, causing the left and right ventricles to contract non-simultaneously. This slow, uncoordinated activation is reflected in a wide QRS complex on an ECG.
Over time, this continuous dyssynchrony can lead to adverse structural changes in the heart, a condition known as Pacing-Induced Cardiomyopathy (PICM). PICM affects patients with high pacing burdens. By stimulating the native conduction system, CV Pace maintains ventricular synchronization and preserves the heart’s pumping function. Clinical data demonstrates that CV Pace is associated with a shorter, more natural QRS duration and a reduced risk of developing heart failure or experiencing a decline in Left Ventricular Ejection Fraction (LVEF) compared to RV pacing.
Patient Candidacy and Device Implantation
Conduction System Pacing is primarily indicated for patients who require a high percentage of ventricular pacing, especially those with pre-existing or anticipated heart dysfunction. Suitable candidates include individuals with atrioventricular block, symptomatic bradycardia, or those with heart failure who require cardiac resynchronization therapy. Furthermore, patients who have developed or are at high risk of developing Pacing-Induced Cardiomyopathy from conventional RV pacing are excellent candidates for an upgrade to CV Pace.
The implantation procedure is similar to a standard pacemaker insertion but requires specialized techniques to position the lead precisely within the septum. Using a dedicated delivery sheath, the electrophysiologist carefully screws the lead into the target area, either the Bundle of His or the left bundle branch region. Successful placement is confirmed by recording specific electrical signals, such as His potentials or left bundle branch potentials, and achieving a narrow QRS complex upon pacing. The long-term benefit of physiological pacing makes it a preferred strategy for maintaining the heart’s natural electrical and mechanical integrity.