Human Anatomy

Pathological Findings in the Dissection Lab

Pacemakers

Pacemakers are implanted in a pocket of skin or subcutaneously over the pectoralis major. The leads are inserted into the left subclavian vein and pass through the left brachiocephalic vein and the superior vena cava, and into the right atrium. The smaller pacemaker shown below had a single lead that passed that passed through the tricuspid valve and was implanted into the interventricular septum. If a second lead is implated it might be implanted in the interatrial septum.

The larger pacemaker shown below is an older model and had two leads passing into the heart. Newer pacemakers are programmed from outside the body and can correct a wide range of arrhythmias.