Left ventricular lead placement

CRT reduces symptoms of CHF and improves cardiac performance in patients with moderate-to-severely symptomatic heart failure, severe left ventricular systolic dysfunction, normal sinus rhythm and a wide QRS complex. Resynchronization therapy significantly reduces hospitalizations in these patients and is highly cost-effective. Perhaps most important, resynchronization therapy for heart failure improves survival for these patients, particularly when employed in conjunction with an implantable defibrillator. However, randomized clinical trials show that a substantial minority of patients are clinical nonresponders. Therefore, critical questions remain with respect to identifying appropriate candidates for CRT, optimal device programming, and left ventricular lead placement. 

Table 4.14 Endocardial approaches for coronary sinus left ventricular 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). 

Removal of the Long Vascular Sheath after Left Ventricular Lead Placement... 

Dekker AL, Phelps B, Dijkman B, van der Nagel T, van der Veen FH, Geskes GG, Maessen JG. Epicardial left ventricular lead placement for cardiac resynchronization therapy optimal pace site selection with pressure-volume loops. J Thorac Cardiovasc Surg 2004 127 1641-7. 

Koos R, Sinha AM, Markus K, Breithardt OA, Mischke K, Zarse M, Schmid M, Autschbach R, Hanrath P, Stellbrink C. Comparison of left ventricular lead placement via the coronary venous approach versus lateral thoracotomy in patients receiving cardiac resynchronization therapy. Am J Cardiol 2004 94 59-63. 

Unlike ventricular lead placement, venous access has little effect on atrial lead positioning. Whether from the right or left venous access, the preformed J or straight electrode with preformed J stylet is easily maneuvered into the atrial appendage or desired position. It should be noted that a right lateral atrial position is more easily achieved by a right venous access. Atrial septal positions are more easily achieved from the left. 

In patients with left bundle branch block, it is advised that right ventricular lead placement be secured before left ventricular lead implantation or coronary sinus osteal localization since traumatic interruption of right bundle branch conduction could lead to the development of catheter-induced complete heart block and the need for urgent ventricular pacing. 

In some cases, identification of a lateral venons branch in which to place a left ventricular lead is not immediately visualized. Most commonly, this is because either an insufficient mount of dye retrogradely filled aU venous branches due to poor balloon occlusion, the balloon itself occlnded the proximal aspect of an eligible lateral vessel, or another more proximal branch was not visualized due to distal balloon or angiographic catheter placement. In these cases, withdrawing the sheath to the ostium of the coronary sinns and performing a hand injection at this location will often identify a vessel snpplying the lateral wall when none was previously seen. 

The CS drains venous blood from the heart into the right atrium. Many branches from the LV flow into the CS, including those from the lateral and posterior LV. Currently, it is there that a left ventricular pacing lead is optimally placed. This maybe best visualized under fluoroscopy from a left anterior oblique (LAO) perspective. Many patients who are candidates to receive a CS left ventricular lead, however, have had myocardial infarctions that may limit the ability to pace from these sites. Stimulation of the left phrenic nerve during ventricular pacing may occur, and can preclude placement there (the left phrenic nerve travels in close proximity to this cardiac region on its way to the left hemi-diaphragm). 

A 63-year-old federal court judge, with no prior arrhythmia or syncope history, requires a biventricular ICD for Class Iff CHF, with the left ventricular lead via an epicardial route. He wishes only initially to have the basic ICD implant, after which he will clear his schedule and return for the epicardial lead. Two weeks prior to the scheduled epicardial lead placement you are called to interrogate his ICD in a local ER trauma ward. Apparently while driving, the patient passed out and struck a tree, amazingly without significant injury. His potassium is found to be 2.1 mEq/dL. The EGMs leading to an appropriate successful shock are seen below. 

The placement of 12-lead electrocardiographic monitoring is often useful in determining left ventricular capture. In addition, patient monitoring equipment should include an automated blood pressure cuff, the presence of continuous oxygen saturation monitoring, as well as intravascular pressure monitoring, both arterial and venous. 

Fig. 7.7 (A) Twelve-lead ECG during pacing demonstrates left bundle-branch block morphology and inferiorly directed mean frontal plane axis, suggesting that the pacing electrode is in the right ventricular outflow tract. (B) Pacing lead placement in the right ventricular apex is indicated by the left bundle branch block morphology and the mean frontal plane superior axis. Notice that the pacemaker does not sense the premature ventricular depolarization (fourth QRS complex in all leads), which indicates that the sensitivity should be increased (by reducing the sensitivity value).

For both atrial and ventricular leads, it is important that the lead not be too shallow. For ventricular leads, this means that slack left in the lead is inadequate, and a shallow atrial lead implies that the angle of the J is much greater than 90°. In Fig. 18.16, placement of both leads is too shallow. The atrial lead... 

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. 

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

Fig. 16.14 Dislodgment of newly implanted atrial and ventricular pacemaker leads (white arrows) during placement of a Swan-Ganz catheter (black arrow). Both leads are looped up into the right internal jugular vein (white arrowhead) revealing the mechanism of dislodgment the balloon at the tip of the Swan-Ganz catheter was left inflated while it was pulled back towards the venous sheath.

---