Pacemaker Overview
1. Components of a Pacemaker
2.
Generator: Contains electronics to generate pacing impulses.
Leads: Two types
o Active leads: Screw into myocardium for stability (higher
perforation risk in elderly).
o Passive leads: Wedged into trabeculae, more prone to
displacement.
2. Pacemaker Implantation
Site: Under local anaesthesia in the subclavian region (left or right
side, based on dominant hand).
Lead insertion:
o Via cephalic vein (direct vision) or
o Subclavian vein (blind puncture, risk of pneumothorax).
Incision and pocket:
o Pocket made between subcutaneous fat and pectoral muscle.
o Incision depends on vein approach (subclavian parallel to
clavicle or cephalic in deltopectoral groove).
3. Lead Placement in the Heart
Right atrial lead: Right atrial appendage.
Right ventricular lead: RV apex or ventricular septum (to mimic
normal conduction).
Left ventricular lead (CRT): Coronary sinus veins for cardiac
resynchronization therapy.
4. Pacemaker Function
Demand pacemakers: Pace only when heart rate drops below a
set threshold.
Mechanism:
o Senses intrinsic contractions → inhibits pacing.
o If no contraction detected within interval → delivers pacing
impulse.
Dual-chamber pacemakers: Coordinate atrial and ventricular
pacing based on sensed activity and intrinsic conduction.
5. Lead Configurations
1. Components of a Pacemaker
2.
Generator: Contains electronics to generate pacing impulses.
Leads: Two types
o Active leads: Screw into myocardium for stability (higher
perforation risk in elderly).
o Passive leads: Wedged into trabeculae, more prone to
displacement.
2. Pacemaker Implantation
Site: Under local anaesthesia in the subclavian region (left or right
side, based on dominant hand).
Lead insertion:
o Via cephalic vein (direct vision) or
o Subclavian vein (blind puncture, risk of pneumothorax).
Incision and pocket:
o Pocket made between subcutaneous fat and pectoral muscle.
o Incision depends on vein approach (subclavian parallel to
clavicle or cephalic in deltopectoral groove).
3. Lead Placement in the Heart
Right atrial lead: Right atrial appendage.
Right ventricular lead: RV apex or ventricular septum (to mimic
normal conduction).
Left ventricular lead (CRT): Coronary sinus veins for cardiac
resynchronization therapy.
4. Pacemaker Function
Demand pacemakers: Pace only when heart rate drops below a
set threshold.
Mechanism:
o Senses intrinsic contractions → inhibits pacing.
o If no contraction detected within interval → delivers pacing
impulse.
Dual-chamber pacemakers: Coordinate atrial and ventricular
pacing based on sensed activity and intrinsic conduction.
5. Lead Configurations
