Types of Pacing Leads

There are two main types of pacing leads - atrial leads and ventricular leads. Atrial leads are thinner leads that are implanted in the right atrium to pace the upper chambers of the heart. Ventricular leads are slightly larger leads implanted in the lower right ventricle to pace the lower chambers. Bipolar leads have two electrical conductors whereas unipolar leads have one conductor and use the pacemaker casing as the other. Most modern pacemakers use bipolar leads which reduce potential risks of electrical interference.

Lead Placement and Anchoring

Cardiac pacing leads are typically implanted via veins into the heart chambers under fluoroscopic guidance. The leads are usually inserted through a vein in the neck, chest or arm and threaded carefully into position. The lead tip contains either an active or passive fixation mechanism to anchor it securely to the heart wall. Active fixation leads utilise retractable helical screw mechanisms whereas passive fixation leads rely on tines or silicone domes that passively anchor in trabeculae. Proper lead placement and anchoring is critical for effective pacing and sensing functions.

Pacing and Sensing Functions

The primary role of a pacing is Cardiac Pacing Leads  to deliver electrical pulses from the pacemaker generator to stimulate the heart muscle during pacing. It contains one or more coiled conductors insulated by a flexible silicone sleeve that transmits current between the generator and myocardial tissue. During sensing, the lead picks up tiny electrical signals from the heart and relays it back to the generator to detect intrinsic heartbeats. Modern multicolored bipolar leads allow both pacing and sensing from the lead tip and ring electrodes.

Lead Issues and Management

Some potential issues that can arise with implanted pacing leads include lead fractures, dislodgments, insulation breaks or conductor breaks. Lead fractures typically occur near the pacemaker generator due to repetitive flexing over decades. Dislodgments occur when the anchoring mechanism fails resulting in lead movement. Insulation or conductor breaks cause intermittent or permanent loss of pacing/sensing functions. Factors like age of the lead, location, integrity of fixation, and medical co-morbidities influence lead performance over time. Some leads may simply require monitoring whereas fracture or dysfunctional leads necessitate replacement procedures. Close monitoring and timely interventions can help maximize lead and pacemaker longevity.

Lead Extraction

Occasionally implanted leads become infected, fractured or deeply entrenched requiring complete removal. Lead extractions are complex invasive procedures performed under fluoroscopy by experienced electrophysiologists. Specialized extraction equipment, tools and techniques are needed based on individual lead properties and embedding characteristics. Transvenous lead removal through femoral/jugular access or surgically-assisted lead excision techniques may be utilized depending on lead vinculum. CompleteExtraction without any retained fragments is the goal to prevent recurrent infections. Careful patient selection and procedural planning together with expertise helps achieve high success and low complication rates during lead extraction.

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