Pacemaker Placement Side
A permanent pacemaker should be placed on the left side initially. 1
Rationale for Left-Sided Placement
The Canadian Cardiovascular Society/Canadian Heart Rhythm Society 2017 guidelines explicitly recommend routine left-sided ICD and pacemaker systems based on superior defibrillation efficacy and mortality outcomes 1. While these guidelines specifically address ICDs, the same anatomic and physiologic principles apply to permanent pacemakers.
Key Evidence Supporting Left-Sided Placement:
Lower defibrillation thresholds: Left-sided systems achieve lower DFTs (8.9 ± 4.2 J) compared to right-sided implants (10.6 ± 3.8 J; P = 0.014) due to the optimal shock vector created between the device can and ventricular myocardium 1
Mortality benefit: Observational data from 627 patients demonstrated significantly higher all-cause mortality with right-sided implants (hazard ratio 1.93; P < 0.004) 1
More predictable impedance: Right-sided systems have unpredictable shock impedance and DFT, making them less reliable 1
When to Consider Right-Sided Placement
Right-sided implantation should only be considered when specific contraindications to left-sided placement exist 1:
- Chronic indwelling intravenous catheters on the left
- Previous left mastectomy with lymph node resection
- Prior infection on the left side
- Left subclavian vein thrombosis
- Existing dialysis access on the left (to preserve vessel integrity) 2
Important Caveat About Laterality
When choosing between right and left sides in the absence of contraindications, right-sided placement is preferable to left-sided placement due to more direct vascular anatomy 2. However, this recommendation from the KDOQI vascular access guidelines specifically addresses central venous catheter placement for dialysis, not permanent pacemakers. The cardiac device guidelines take precedence for pacemaker placement decisions.
Special Populations
Pediatric patients and congenital heart disease: The same left-sided preference applies, though epicardial approaches may be necessary in neonates or patients with intracardiac shunts 3, 4. In patients with right-to-left shunts, transvenous systems should be avoided entirely due to paradoxical embolus risk 5.
Nondominant extremity preference: When choices are equivalent, the nondominant side is preferred, but this is secondary to the left-sided recommendation 2.