Where is a single chamber pacemaker lead typically placed?

Single Chamber Pacemaker Lead Placement

A single chamber pacemaker lead is placed in either the right ventricle (most commonly at the right ventricular apex) or the right atrium (typically in the right atrial appendage), depending on the clinical indication. 1

Ventricular Lead Placement (Most Common)

When ventricular pacing is required, the lead is positioned in the right ventricular apex, which is the traditional and most frequently used site 1:

• The lead passes through the tricuspid valve and advances along the floor of the right ventricle to reach the apex 1
• On chest radiograph, ideal positioning shows the electrode tip at the right ventricular apex with the tip turned down slightly 1
• On ECG, right ventricular apical pacing produces a left bundle branch block configuration with left axis deviation 2

Technical Insertion Details

The insertion technique involves specific maneuvers 1:

• The wire is advanced until it lies almost vertically in the right atrium
• It is then rotated 180° until it points downwards and to the patient's left
• The wire should pass through the tricuspid valve and slide along the floor of the right ventricle to the apex 1

Common pitfall: Inadvertent cannulation of the coronary sinus, which directs the electrode tip upwards and to the left toward the left shoulder, appearing posterior on lateral radiograph rather than anterior like proper right ventricular placement 1

Atrial Lead Placement (Less Common)

When atrial pacing is required, the lead is positioned in the right atrial appendage 1:

• Atrial leads have a preformed "fish hook" shape requiring leftward orientation 1
• The tip must point upwards into the right atrial appendage for stable positioning 1
• On lateral chest radiograph, atrial electrode tips should point forwards toward the anterior chest wall 1
• Atrial lead positioning requires more experience and should not be attempted in emergencies 1

Clinical Indications Determining Lead Location

For ventricular-only pacing (VVI mode): 1, 3

• Permanent atrial fibrillation or longstanding persistent atrial fibrillation with no plan for rhythm restoration 1
• Symptomatic bradyarrhythmias when atrial hemodynamic contribution is not significant 3
• Following AV junction ablation for rate control 1

For atrial-only pacing (AAI mode): 1

• Sinus node dysfunction with intact AV conduction
• When ventricular pacing is not required

Important caveat: Single chamber ventricular pacing (VVI) is contraindicated when pacemaker syndrome is present or anticipated, as loss of AV synchrony can cause symptoms including light-headedness, syncope, or palpitations 1, 4, 3