What is the optimal lead positioning level to administer therapy?

Optimal Lead Positioning for Cardiac Device Therapy

Right Ventricular Lead Placement

For standard ICD and pacemaker implantation, the right ventricular apex remains the traditional and most commonly used site, though RV septal and RV outflow tract positions are equally effective for sensing and defibrillation in most patients. 1

Standard Approach

• The RV apex has well-established long-term data and remains the conventional target site for ICD lead placement 1
• However, chronic RV apical pacing (>40-50% of the time) is associated with increased heart failure hospitalizations and mortality, particularly in patients with reduced ejection fraction 1

Critical Caveat for CRT Patients

• In CRT-D patients, nonapical RV lead location (septal or RVOT) is associated with a 2.5-fold increased risk of ventricular tachyarrhythmias and death compared to apical positioning, particularly in the first year after implantation 2
• There is no benefit of nonapical RV lead location in clinical outcomes or echocardiographic response in CRT patients 2
• Therefore, for CRT devices, RV apical positioning should be preferred over septal or RVOT locations 2

Left Ventricular Lead Placement for CRT

For patients requiring Cardiac Resynchronization Therapy, the LV lead should target the lateral or posterolateral wall via the coronary sinus, avoiding apical positions. 1

Optimal LV Lead Strategy

• Target the posterior and lateral walls of the LV, as these locations provide the best pacing site 3
• Apical LV lead position significantly increases risk of heart failure or death compared to basal or midventricular positions 1
• Wider separation between LV and RV leads provides superior outcomes 1
• The segment with the latest preoperative LV contraction should correspond with the LV lead position for optimal benefit 4

Transvenous Approach Success Rates

• Coronary venous lead implantation for biventricular pacing has an 81-99% success rate 3
• Common causes of failed percutaneous placement include anatomic barriers (SVC or coronary sinus obstruction, inadequate coronary venous anatomy) or technical issues (failure to cannulate coronary sinus, dissection, high pacing thresholds, diaphragmatic pacing, lead dislodgement) 3

Surgical Epicardial Lead Placement

When transvenous coronary sinus lead implantation fails, surgical LV epicardial lead placement is almost always successful and provides access to the entire posterior and lateral LV walls. 3

Indications for Surgical Approach

Surgically placed epicardial pacing leads are indicated when standard transvenous lead placement is not feasible or contraindicated 3:

• Inability or failure to place an adequate LV lead in patients requiring biventricular pacing 3
• Permanent pacing in pediatric patients or patients with tricuspid valve prostheses 3
• Recurrent or prolonged bacteremia 3
• Congenital or acquired venous anomalies that preclude transvenous access 3

Surgical Technique Selection

• Thoracoscopic and robotic approaches are preferred over thoracotomy due to minimal morbidity 3
• Thoracotomy in fragile heart failure patients has been associated with bleeding, stroke, hypotension, and arrhythmias 3
• Minimally invasive procedures require 60-90 minutes operative time with 4-5 day hospital stay 3
• Patients with prior thoracotomy or sternotomy may have limited pericardial/epicardial accessibility 3

Lead Type Considerations

• Steroid-eluting epicardial leads may be preferable to screw-on leads 3
• Implantation of 2 epicardial leads may be considered to provide backup capability if one lead fails or becomes dislodged 3
• Echocardiography with tissue Doppler imaging and electrophysiological measurements can facilitate optimal LV epicardial pacing site selection 3

Concomitant Cardiac Surgery Approach

In patients undergoing coronary artery bypass grafting or mitral valve surgery who are current or future CRT candidates, the surgeon may elect to place an LV epicardial lead at the time of surgery. 3

Specific Criteria for Prophylactic Lead Placement

This approach applies to patients with 3:

• Medically refractory, symptomatic heart failure
• Ischemic cardiomyopathy or dilated cardiomyopathy
• Prolonged QRS interval
• LV end-diastolic diameter ≥55 mm
• LVEF ≤35%

Important Exclusion

This approach is probably not indicated for patients expected to have substantial improvement in LVEF after cardiac surgery (e.g., patients with extensive viable myocardium undergoing revascularization) 3

Single-Coil vs. Dual-Coil ICD Leads

Single-coil ICD leads are preferred over dual-coil leads for left-sided implants when defibrillation threshold testing demonstrates adequate safety margin. 1

• Defibrillation threshold testing should be strongly considered in patients with single-coil leads, right-sided implants, epicardial systems, or massive cardiac hypertrophy 1

Key Clinical Pitfalls to Avoid

• Avoid excessive RV apical pacing (>40%) in patients with reduced ejection fraction—consider upgrading to biventricular pacing if RV pacing burden exceeds this threshold 1
• For CRT, avoid apical LV lead positions which significantly worsen outcomes; target lateral or posterolateral walls instead 1, 4
• In CRT-D patients, avoid nonapical RV lead positions (septal/RVOT) as they increase ventricular tachyarrhythmia risk 2.5-fold 2
• Always verify adequate defibrillation thresholds with single-coil leads, particularly in anatomically challenging cases 1
• For external defibrillation in patients with existing ICDs, position pads at least 8 cm away from the device to avoid changes in pacing thresholds or sensing measurements 1