Cardiac resynchronization therapy (CRT) improves symptoms, quality of life and reduces hospitalization in patients with New York Heart Association (NYHA) class III-IV classification and left bundle branch block.^1,2 Inaddition,implantation of a CRT system with or without defibrillator reduces mortality in this patient population.^3,4 More recently, CRT was shown to reduce heart failure progression and induce left ventricular reverse remodeling in patients with NYHA class I and II symptoms.^5,6 In this article, we will review the techniques used at Emory University Hospital Midtown for CRT implantation as well as tips for a successful and safe procedure.

Implant Techniques

Venous Access

   A left subclavian venous access is the preferred venous entry to cannulate the coronary sinus (CS) because it provides a more natural curve for the guide catheter to follow from the shoulder to the CS os. A right-sided subclavian venous entry is used at times when upgrading an existing system or when the left subclavian vein is occluded. In the case of a new implant we routinely use the cephalic vein to place the right atrial (RA) and right ventricular leads (RV), but we use a subclavian vein puncture to provide a separate access site for the left ventricular (LV) lead. By placing the RV lead first, we provide back-up pacing in case instrumentation of the right bundle branch by the guide catheter or the wire results in complete heart block in patients with preexisting left bundle branch block (LBBB).

   When upgrading a pacing system, a venogram of the subclavian vein is routinely performed in order to guide the implant procedure. In the case of an occluded vein, one could implant an LV lead in the contralateral shoulder and tunnel the lead to the old system. Alternatively, abandoning the old system and implanting a new one on the contralateral shoulder could be done. A third option is to sacrifice one of the old leads to serve as a rail for a laser assisted extraction and create venous access to replace the old lead and add a new LV lead.

CS Access
In patients with heart failure and dilated RA or LV, the CS ostium location is distorted and usually lower and more posterior. Several fluoroscopic landmarks could be used to localize the CS. In the right anterior oblique (RAO) view, the lucent “fat-pad” overlying the atrial-ventricular groove marks the course of the CS. Other markers such as calcification of the right coronary artery could also serve as a guide to the CS. The left anterior oblique (LAO) view best guides CS entry since in this view the CS runs toward the spine to encircle the mitral annulus.⁷ We usually access the CS in the AP view utilizing a 3-step approach:⁷

• Step 1: advance the guide to the lower right atrium with the tip pointing to the cardiac apex, and once in this position, pull the guidewire into the guide

• Step 2: bounce the guide off the RA floor until the tip points upward

• Step 3: counterclockwise rotation usually points the tip posterior to cannulate the CS ostium. At this stage, you probe with the guidewire to confirm CS location.