Retrosternal lead placement: an attractive alternative to subcutaneous tunneling

Abstract

Complex lead placement is on the rise. When ipsilateral lead placement is unavailable, a retrosternal approach offers minimal cosmetic defects while minimizing lead injury. A retrosternal technique has yet to be described in the literature. Here, we describe our technique, tricks, and pitfalls to performing such an operation in three patients.

Introduction

Cardiac resynchronization therapy (CRT) is a recognized therapy for the management of severe left ventricular dysfunction, advanced congestive cardiac failure, ventricular dyssynchrony, and failure of optimal medical therapy to achieve improvement in clinical status [1]. Complex device placement is often required and it is on the rise [2]. In those patients requiring upgrade/revision, multiple factors may make the left-sided venous anatomy unsuitable for transvenous lead placement (thrombosis, infection, need for ipsilateral radiation, etc.). In those receiving a new left ventricle (LV) epicardial lead, often it requires crossing the midline to connect to a right-sided generator. This can be accomplished by either presternal or retrosternal approach. Often, patients have undergone previous cardiac surgery (mediastinal scarring) resulting in avoidance of the retrosternal approach, instead choosing subcutaneous tunneling [3, 4]. Concerns with a presternal course arise when patients still have a potential need for redo median sternotomy. Additionally, cosmesis with this technique can be an issue especially in people with a thin body habitus. Here, we present three patients who underwent successful completion of retrosternal lead placement during CRT system upgrade/revision with previously placed right-sided generators. The technique, tricks, and pitfalls to performing such an operation are described.

Case reports

Case no. 1

A 67-year-old woman who is s/p aortic valve replacement in 2005 that was complicated by complete heart block managed by placement of a dual chamber transvenous pacemaker. This was upgraded to an implantable cardioverter defibrillator (ICD) in 2012 and to a CRT-defibrillator (CRT-D) system in 2013 with the addition of a coronary sinus lead. All leads were placed via the left subclavian vein. Redo aortic valve replacement was performed in 2014 for structural valve degeneration. Following a motor vehicle accident, she developed redness over her generator site. This was unresponsive to antibiotics. The entire system was removed as it was found to be infected and a temporary pacemaker was placed via the right internal jugular vein during completion of antibiotics.

Case no. 2

A 69-year-old male with ischemic cardiomyopathy, who has undergone right-sided (occluded left subclavian vein) ICD implant and coronary artery bypass grafting (CABG), now requiring an upgrade to a CRT-D system. He had an attempted coronary sinus lead placement which was unsuccessful secondary to unsuitable venous anatomy.

Case no. 3

A 47-year-old woman with history of non-ischemic dilated cardiomyopathy, with ICD in situ, suffered an inappropriate ICD discharge secondary to lead fracture (Medtronic model 6947 Quattro). The 12-year-old lead required complex laser lead extraction. The left-sided venous anatomy was now unsuitable to ICD and CRT-D placement.

Operative technique

A computed tomography angiogram is performed in all patients prior to going to the operating room. Cardiopulmonary bypass is on standby for each case. The patient is positioned in a slight lateral decubitus position with a left-sided bump to elevate the left shoulder and chest. The left ventricle (LV) leads are placed through an anterolateral thoracotomy. After adequate lead thresholds are obtained, a right-sided generator pocket is developed or previous right-sided generator capsule incised. A long “Chitwood clamp” (Fig. 1a) is used to develop a retrosternal tunnel to the right side of the chest (Fig. 2). The key maneuver in blunt tunnel dissection is keeping the dull clamp tip (Fig. 1b) juxtaposed to the posterior sternal table or risk injury to the heart. The tunnel is made at the level of the diaphragm. Curvature of the clamp allows for easy exit through a right-sided intercostal space and into the newly developed generator pocket. Often unnecessary, an umbilical tape can be used to secure the tract. The clamp is withdrawn and the leads are grasped by the clamp where they are passed into the generator pocket via the retrosternal tunnel. The management of the thoracotomy and the generator pocket is standard. The leads utilized in the cases were either Medtronic model 4968-60 or Enpath Medical model 511212.

Fig. 1.

a “Chitwood clamp” used for minimally invasive cardiothoracic surgery. b Magnified view of the blunt tip

Fig. 2.

Operative depiction: the patient is in a semilateral position where a thoracotomy has been performed. The Chitwood clamp is being used to develop the retrosternal tunnel

Postoperative

Post-procedure chest X-ray (CXR) confirmed good lead position and no pneumothorax in all patients (Fig. 3). Their postoperative courses were uncomplicated and each patient was discharged in a timely fashion. At 1 year follow-up, cases 1 and 3 are doing well with no complications with their CRT-D systems. Four months after the procedure, case 2 passed away at home of unknown causes; his system had been functioning well at the time.

Fig. 3.

Case 1. a Preoperative CXR. b Postoperative CXR demonstrating a new right-sided device and the proximity of new left-sided leads to the posterior sternal table. c Postoperative computed tomography showing the juxtaposition of the leads (arrowhead) to the mediastinal structures/posterior sternal table

Discussion

Data from the REPLACE registry shows that patients undergoing replacement of a chronically implanted pacemaker/ICD are generally at increased risk for procedure-related complications if a transvenous lead is added to replace a defective electrode or for device upgrade [5]. Conventional transvenous lead implantation may be difficult/impossible in patients with aberrant venous anatomy, superior vena cava (SVC) obstruction, persistent left SVC, innominate vein stenosis, or subclavian vein thrombosis [4]. Successful placement of leads in these settings has required innovation and modification of traditional surgical approaches. This often requires a right-sided device with left-sided leads.

Alternative approaches have included transthoracic transatrial placement or contralateral subclavian access with transvenous lead placement, both with subcutaneous lead tunneling [6, 7]. Epicardial lead placement via a minimally invasive video-assisted thoracoscopic surgical (VATS) access, left-sided mini-thoracotomy, or a subxiphoid approach is another alternative [4, 6]. In patients with right-sided generators, the left-sided lead has generally taken a subcutaneous course to the generator. Jaroszewski et al. describes subcutaneous tunneling of the lead below the xiphoid in an effort to prevent injury to the lead, in the event a future median sternotomy is performed [4]. Sadarmin et al. describes a subcutaneous presternal approach utilizing a tunneling tool and a single lumen Groshong central line kit [3]. Bhagwandien et al. describe a case where contraindications existed to both transvenous and subcutaneous ICD (S-ICD) placement. The patient underwent an epicardial pace/sense lead along with substernal SVC coil lead through a left-sided mini-thoracotomy [6].

There are several disadvantages to subcutaneous tunneling. In thin patients, there is minimal presternal fat and a tunneled subcutaneous lead can be of prominence in this area. Some patients often “pick” at palpable and superficial leads similar to twiddler’s syndrome. Additionally, the lead would exit an intercostal space on the left side and then travel across the sternum in a subcutaneous plane to the generator on the right side. When performing a redo sternotomy, several technical issues arise. The lead will be present in the subcutaneous area crossing the surgical field. The surgeon will have to work posterior to the lead to get to the sternum which can be a nuisance. Once the redo sternotomy has been performed, working around the lead, a sternal retractor has to be placed and pried open. This stretches the subcutaneous lead as it is fixed at the exit site of the thoracotomy and all along the subcutaneous tunnel. If the lead is tunneled retrosternally and just above the diaphragm, it can be easily dissected off the xiphoid and inferior sternum. Once the sternal retractor is placed, there is absolutely no stretch on the lead as it is within the mediastinum and it is not crossing the surgical visual field. One disadvantage to the retrosternal technique is from an infection standpoint; removal of the system would be more extensive compared to that of subcutaneous tunneling.

When considering the complication of lead fracture, the risk of stretching the lead is higher with subcutaneous tunneling. The lead is fixed at the exit site of the left thoracotomy and in its entire subcutaneous course as it crosses the sternum and all the way over to the right-sided generator. When the sternal retractor is opened, the lead will be stretched as there will be progressive tension on the lead. With retrosternal tunneling, most of the lead is present is the mediastinum. Only a small portion exits on the right chest and attached to the right-sided generator. The leads within the sternum can be easily mobilized, as fibrous capsules form around them. The mobilized leads within the mediastinum allow for wide opening of the retractor without subjecting the leads to any added stretch.

Retrosternal lead tunneling has yet to be described in the literature. We just described three patients managed with this technique. These patients underwent epicardial lead placement through a left-sided mini-thoracotomy with retrosternal tunneling of the leads using a “Chitwood clamp.” Postoperative recovery was uneventful. The technique requires adherence to certain precautions to avoid complications. The femoral vessels are marked, groins are prepped into the field, and blood readily available. The curve of the clamp must be facing upwards during the retrosternal dissection and the tip must be in contact to the posterior sternal table. These procedures are performed with “pump standby” at our institution. Contraindications to the procedure include pseudoaneurysms, patent grafts, or conduits that cross the proposed retrosternal path.

In conclusion, complex lead placement is rising. In patients who are unable to undergo ipsilateral transvenous lead placement, retrosternal lead tunneling is a viable alternative. Retrosternal tunneling allows for the leads to be behind the sternum, thus being non-palpable, and reduces the risk of injury during redo sternotomy compared to subcutaneous tunneling. We believe the retrosternal technique can be adapted to any approach that calls for crossing of the midline by a lead.

Compliance with ethical standards

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in this study.

Conflict of interest

The authors declare that they have no conflict of interest.