Left-sided lead placement

Recently, thoracoscopic approaches, less risky than thoracotomy, have been developed for the placement of left ventricnlar leads (155-157). Still to be resolved are the issues of lead instabihty and unreliable sensing and pacing characteristics. On the horizon, with respect to an epicardial approach, is a percntaneons technique utilizing robotics for left-sided lead placement. 

After venous access, some consideration should be given to the sequence of lead placement. Some operators prefer to place the RV electrode first for emergency RV pacing, should heart block ensue because the heart failure patients commonly have a left bundle branch block and any trauma to the conduction system or right bundle may result in complete heart block. Other operators choose to place the coronary sinus lead first and, if necessary, depend on heart rate support via a temporary transvenous pacemaker placed via the femoral vein. The issue of failure speaks for placing the coronary sinus lead first. Should the procedure fail with unsuccessful left-sided left ventricular lead placement and the patient has already received right-sided electrodes, a pacing system may be left without an indication unless a future second attempt is considered. As more and more systems are placed for a primary prevention indication like MADIT II, this has become less problematic (153). 

Fig. 7.2 Serial anteroposterior fluoroscopic images taken during transvenous removal of a left-sided dual-chamber implantable cardioverter-defibrillator (ICD) system. After placement of a temporary right-ventricular (RV) pacing system

Anatomic variations can alter the placement of the pacing system and therefore the radiographic appearance. It is not possible to discuss all potential anatomic variations. However, one anatomic variation does merit discussion - a persistent left superior vena cava. A permanent pacing system can be implanted via a persistent left superior vena cava (Fig.18.21). (If this anatomic variation is noted before pacemaker implantation, it is easier to implant the system via the right side if the patient has a normal right superior vena cava.) If pacing leads are implanted through a persistent left superior vena cava, the lead in the PA projection descends within the left side of the cardiac shadow and enters the atrium and then the ventricle by communication of the left superior vena cava and the coronary sinus. On the lateral projection, the ventricular lead is seen on the posterior cardiac wall within the coronary sinus. 

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