Active-fixation leads types

Before starting the extraction procedure, the operator must identify the type and manufacturer of leads submitted to removal. One must identify lead fixation mechanism and type of fixation in case of an active fixation lead in some active fixation leads, special stylets are needed in order to unscrew the screw. After lead identification, the procedure of lead extraction consists of lead preparation and sheath application when gentle manual traction is unsuccessful. 

There are essentially two types of active fixation leads both involve a helix or screw as a fixation mechanism. The first and simplest design incorporates a continuously exposed screw. Because the screw is exposed, problems may be encountered as the exposed screw seemingly catches on every endocardial stracture. Usually, the lead tip is freed by counterclockwise rotation of the lead body. In an attempt to avoid this problem, some manufacturers have eoated the exposed screw with some form of sugar that dissolves, ultimately exposing the screw (Fig. 4.36). The problem with this remedy is that, once the eoating dissolves, the exposed screw once again can hook on any endocardial stmcture. 

The second type of common active fixation lead design employs a retractable/extendable screw that is mechanically activated (Fig. 4.37). This lead avoids the problem of hang-up and is much easier to work with. One merely maps a point of fixation and activates the fixation mechanism. 

P-wave amplitudes than their non-drug-eluting counterpart [10, 11]. Another type of drug-eluting lead is designed with a porous ceramic or silicone collar soaked with dexamethasone sodium phosphate positioned immediately proximal to tip electrode. This system is used in steroid-eluting, active fixation screw-in leads and shows similar performance as the MCRD. Steroid elution is available on atrial and ventricular leads and as well as coronary venous and epicardial leads. 

Numerous epicardial active fixation devices are available but are not commonly used. The radiograph in Fig. 18.24 shows four different types of leads in one patient two epicardial leads and two endocardial leads. In this patient, previous epicardial pacing did not have long-term success. Two types of leads had been used, including a stab-in epicardial-myocardial lead and a screw-in epicardial-myocardial lead. A transvenous ventricular passive fixation lead and an active fixation atrial lead are also visible. Details of these leads are also seen on the lateral view. 

Although the specific type of transvenous lead often cannot be identified, it may be helpful to determine whether the lead is active or passive fixation. Specifically, this may be helpful when lead extraction is being contemplated and the lead model and manufacturer are unknown. 

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