Direct visualization of an atrial transseptal left ventricular endocardial lead implantation within an isolated heart.

Introduction

Left ventricular (LV) endocardial pacing is a relatively new therapy that may offer several advantages over coronary venous lead placement for biventricular resynchronization therapy, including access to more regions of the LV, faster impulse propagation, avoidance of phrenic nerve stimulation, and more physiologic LV activation. We report a case of transseptal implantation of a pacing lead in the LV chamber from a superior approach, which was observed using direct visualization, for better understanding of the implantation procedure and device–tissue interactions during the procedural steps.

Case report

Endoscopic cameras (IplexFX, Olympus Corporation, Tokyo, Japan) were placed within the right atrium, left atrium (LA), and LV of a human donor heart (LifeSource, St. Paul, MN) that was deemed not viable for transplantation. The heart was reanimated and perfused with a clear Krebs–Henseleit buffer according to previously described methodologies.2, 3 The intrinsic sinus rhythm of the beating heart was 70 bpm. An external view of the experimental setup is shown in Figure 1 and Online Supplementary Video 1.

Figure 1

External view of the experimental setup showing the right atrium (RA), left atrium (LA), superior vena cava (SVC), aorta (Ao), pulmonary artery (PA), left ventricle (LV), and right ventricle (RV). Access to the heart was gained via an introducer placed in the SVC cannula.

Initially, the right atrial septum was located using a deflectable catheter, and the fossa ovalis was tented using a dilator and a subselection catheter as viewed from the right atrium (Figure 2A) and LA (Figure 2B) (the delivery system, leads, and implant technique are not approved for investigational or commercial use in the United States). The fossa ovalis then was punctured using a radiofrequency (RF) wire (Figure 2C) and a generator (25 W at 2 seconds), and the RF wire (Baylis Medical Inc, Montreal, Quebec, Canada) was advanced into the LA (Figure 2D). The dilator was subsequently placed across the fossa ovalis within the LA using the RF wire as a guide (Figure 2E). Next, a subselection catheter was placed over the dilator, across the septum and into the LA (Figure 2F). After the dilator was withdrawn, the subselection catheter was directed toward the mitral valve, and the RF wire was advanced across the mitral valve without impinging on the chordae tendineae or leaflets (Figure 2G). Thereafter, the subselection catheter was guided over the RF wire and across the mitral valve (Figure 2H). The RF wire was removed, which allowed the subselection catheter to move freely within the LV. Note that in a clinical setting, a pressurized, continuous heparinized saline flush would then be attached to subselection catheter after removal of the RF wire. The subselection catheter was positioned on the lateral free wall of the LV, and an active fixation lead (3830 SelectSecure, Medtronic Inc, Mounds View, MN) was inserted into the catheter and fixated (Figure 2I). After fixation, the subselection catheter was withdrawn to ensure that the lead was fully fixated in the myocardium. The procedure can be viewed in Online Supplementary Video 1.

Figure 2

Transseptal left ventricular endocardial lead implantation sequence.

Discussion

LV endocardial lead placement enables physiologic pacing and freedom to select an optimal LV pacing site in order to improve cardiac resynchronization therapy (CRT) outcome.4, 5, 6 Garrigue et al studied 15 patients with epicardial lead implants via the coronary sinus and compared them with 8 patients with endocardial leads placed by conventional transseptal puncture secondary to unsuitable coronary sinus anatomy. They reported a significant improvement in echocardiographic and Doppler variables in the patients who had undergone endocardial pacing. In addition, Bracke et al reported that endocardial LV pacing improved clinical efficacy in a nonresponder who previously had been implanted with a traditional CRT system. As such, implementation of endocardial LV pacing ultimately will depend on safe, effective, durable instrumentation and reliable, reproducible intraprocedural methods to identify the optimal LV pacing site. Another key to the future success of this pacing technique will be the ability to demonstrate significant benefit of LV endocardial pacing over the risk associated with thromboembolism in advanced heart failure patients with chronic pacing leads in the LV. Rademakers et al observed thromboembolic complications with endocardial pacing; however, the risk seemed to be strongly correlated with a subtherapeutic level of anticoagulation. Interestingly, endocardial pacing did not aggravate mitral regurgitation in these patients. Preliminary results from the ALSYNC (ALternate Site Cardiac ResYNChronization) study, which used the same techniques and delivery system demonstrated here, indicate that implantation of an LV endocardial pacing system is feasible, safe, and clinically successful. However, long-term follow-up data are needed to assess the long-term safety and efficacy of this approach to LV pacing/CRT.

In this case study, direct visualization aided in LV endocardial lead placement and demonstrated the feasibility of a novel LV endocardial lead delivery system. There was no impingement on the chordae tendineae or leaflets when the lead was placed across the mitral valve; however, the lead may be more difficult to position as precisely as when fluoroscopy is used in the clinical setting. Although placement of an LV lead using direct visualization is not representative of the visualization techniques available in a clinical setting, the images presented here have notable educational value for both clinicians and design engineers.

KEY TEACHING POINTS

• Implantation of an LV endocardial lead is feasible using a superior atrial transseptal approach. • A catheter-based delivery system with RF wire can be used to locate and puncture the atrial septum, and subsequently guide/implant an active fixation lead in the LV with minimal steps. • An LV endocardial lead can be placed without impingement of the mitral valve.