Right ventricle lead fixation

Transvenous ICD leads are anchored in the right ventricle by small flexible tines at the lead tip that intertwine in small structures in the chamber ( passive fixation ) or by a helix at the lead tip that can be screwed into the myocardial tissue ( active fixation ). The distal defibrillation coil rests within the right ventricle. Dual coil leads are designed such that the proximal coil is positioned in the superior vena cava. 

Lead fixation provides lead-tip stabilization during the hours immediately following the procedure. Fixation may be passive or active. Passive means that no part of the lead itself is actually embedded in the endocardium. After first experiences with flanged or helicoidal-shaped tips, endocardial leads now incorporate different numbers and kinds of tines at the tip that ensnare in trabeculated tissue of the right atrium or ventricle, providing stabilization (Fig. 1.8) [2]. Active fixation means that part of the lead actually embeds in the heart tissue for fixation. These leads utilize screw-based mechanisms to adhere to the myocardium to provide lead stability. Some leads incorporate screws that are electrically active, whereas others are inactive. Therefore, some screws are extendable and retractable from the lead tip and others are fixed on... 

Fig. 3 2 Posteroanterior (a) and lateral (b) chest X-ray showing a patient with four screw in leads, including a coronary sinus (CS) active fixation lead (Medtronic Starfix). RA, right atrium, RV, right ventricle, ICD, implantable cardioverter-defibrillator, PS, pericardial space...

It has been this author s practice to reserve the positive screw-in fixation lead in the ventricle for unique circumstances. Such circumstances include a dilated cardiomyopathy where the right ventricle is extranely thin with little or no trabeculations for fined fixation. The positive fixation screw-in lead is also ideal if atypical electrode position is desired. Such a circumstance includes electrode placement high on the interventricular septum. 

Fig. 1 A dual-chamber pulse generator and two leads. The pulse generator is a hermetically sealed titanium can containing an Lil power source, circuitry (including microprocessor), niobium or tantalum/sapphire feed throughs, and a connector to receive two leads. The lead with the straight distal tip is inserted in the right ventricle while that with the J shape is placed in the right atrial appendage. Both leads are bipolar (two electrodes within the heart). The tiny projections (tines) at the tip help provide fixation for the distal stimulating electrode...

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