Fixation:

Active fixation: usually where the lead is kept in contact with a metal screw-in fixation. Active fixation leads offer a wider choice of implant sites, are often required for atrial pacing in post bypass patients but tend to have a higher pacing threshold.

Passive fixation: usually where the lead is kept in contact with rubber fins or tynes. These leads tend to have the best pacing thresholds.

Cardiac surfaced paced:

Endocardial: A lead that is passed through the venous system and contacts the endocardium of the heart. These can be active or passive fixation.

Epicardial: These are leads that are placed directly on the epicardium.

screw-in: leads which are easier to implant and are unipolar only.

sew on: the steroid version of these patch leads have better long term performance and are available in unipolar and bipolar configurations.

Polarity:

Unipolar: These leads are the thinnest and probably have the highest reliability.

Bipolar: These leads have two electrodes and offer improved rejection of far field sensing (cross talk) but usually larger and may not be as reliable.

Multipolar: These are special purpose leads such as those used for single lead VDD pacemaker implants.

Insulation

Silicone. Silicone leads tend to have better long term reliability but are thicker and stickier and more difficult to implant.

Polyurethane. These leads are the thinnest, slide the best and are the easiest to implant. They may have a decreased longevity which may depend on the type of polyurethane used. Publications indicate a reasonable survival for atrial leads(3)

Lead Tip

steroid eluting. These leads elute a small amount of steroid and tend to have a lower pacing threshold(4)(5) and can prolong pacemaker life.

non-steroid eluting. These leads tend to be less expensive and usually have higher pacing thresholds but can provide adequate sensing thresholds.

carbon tipped. One publication showed that short term pacing thresholds were better with steroid added to these leads but long term the thresholds where the same(6)