Left Ventricular Lead Placement Outside the Cardiac Veins

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Left Ventricular Lead Placement Outside the Cardiac Veins CHARLES KENNERGREN  |  JOHN M. MORGAN

BACKGROUND Cardiac resynchronization therapy (CRT) has proved a highly effective treatment for many patients suffering from heart failure.1 The nonresponder rate in many series is, however, still in the 30% range. There are many facets to the issue of “nonresponse.” Clinical conditions vary widely and impact on the clinical utility and outcomes of CRT: QRS width, ejection fraction, cause of ischemic or nonischemic disease, and location of ischemic scars. Thus careful patient selection is critical for CRT response. Correct pacing location for stimulus delivery is equally critical to achieve response. Nonischemic and especially ischemic disease expression will affect how depolarization occurs in the myocardium. Many recent studies have focused on finding the optimal location for delivery of left ventricular (LV) stimuli in relation to right ventricular (RV) stimulation and in finding the optimal timing of impulses. In several studies stimulation at the point of latest LV activation has proved a simple, yet effective principle to achieve good response.2-5 Transvenous lead placement via the coronary sinus limits, by anatomy, and lead placement to available side branches, often do not achieve optimal resynchronization of the ventricular mass. In addition to anatomic venous limitations, vessel obliteration following infarction is common in ischemic patients. Considering the heterogeneity of patients and that LV stimulation at present is often delivered haphazardly, the current responder rate is surprisingly high. LV lead placement is often considered satisfactory if energy is delivered to the lateral aspect of the left ventricle, diaphragmatic stimulation is absent, and thresholds are acceptable. In addition, right atrial (RA) and RV leads are usually not prescriptively placed. There is the potential for better CRT outcomes with the careful prescription of LV pacing location, and this may be best achieved either by surgical epicardial lead placement or LV endocardial lead placement, as both approaches overcome the inherent limitations imposed by coronary sinus (CS) anatomy.

SURGICAL EPICARDIAL LEFT VENTRICULAR LEAD PLACEMENT Direct or surgical epicardial placement is an attractive lead implantation alternative allowing energy to be delivered to the LV at any location, thereby avoiding the transvenous route limitations (Case Study 31-1). Very importantly, direct epicardial lead placement also allows electrical mapping before placement of the LV lead. A simple principle that seems to be highly efficient for achieving response is to place the LV lead in a position where the longest sensed R-R interval is found. This principle has been highly effective in the reported literature6 and also in the authors’ experience, reducing nonresponders to a small group of patients with multiple and significant infarction scars. It has also been shown that reverse anatomic remodeling occurs at the same rate after either transvenous or direct lead placement.7

LEFT VENTRICULAR ENDOCARDIAL PACING LV endocardial pacing is another alternative pacing approach to that offered by “conventional” CS or “surgically placed” epicardial pacing, for LV activation in the context of CRT.8-10 Its purpose is delivery to the endocardial surface of a pacing stimulus for initiation of myocardial activation. The pacing stimulus initiates an activation wave front from the point at which that activation stimulus is delivered. Such a stimulus may be delivered in unipolar or bipolar mode from pacing devices. There is some evidence that LV endocardial pacing may offer improved functional outcomes for CRT recipients compared with conventional approaches,11-16 but that possible advantage needs to be balanced against the procedural challenges and the requirement for long-term anticoagulation to avoid thromboembolic risk.17 LV endocardial pacing offers the “landscape” of the endocardial surface for pacing and therefore choice of optimal pacing site (however that choice might be made), unlike the restricted CS anatomy. Pacing systems comprise pacing electrodes mounted on standard pacing leads, self-contained “leadless” pacemakers with integral bipolar pacing electrodes, and “independent” pacing electrodes that are fixed to the endocardial surface but which have physically remote power units to deliver the necessary energy wirelessly to the pacing electrode for the development of potential difference at the pacing electrodes, which then initiate myocardial activation. The “leadless” pacemakers are currently indicated only for RV pacing. For reasons of size and procedural risk, it is unlikely that such devices will be clinically available for LV endocardial pacing in the immediate future. Furthermore, the delivery tools and procedural approaches for their use in the left ventricle have yet to be developed, and therefore these technologies are not considered further. The focus is on the clinically available “conventional” lead-based approaches to LV endocardial pacing with brief reference to the investigational “independent” pacing electrode technology.

SURGICAL EPICARDIAL LEAD PLACEMENT TECHNIQUES Epicardial lead placement has some potential drawbacks that must be solved to make epicardial lead placement more common. Traditional full left-sided thoracotomy, if not adequately modified, can be associated with significant and unnecessary morbidity. Fortunately, several less invasive and, from a morbidity point of view, more attractive approaches are available and will be discussed (Case Study 31-2). One remaining disadvantage with epicardial stimulation difficult to overcome is that endocardial stimulation in several studies has proved more effective than epicardial; this disadvantage also applies to transvenous CS stimulation.

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CHAPTER 31  Left Ventricular Lead Placement Outside the Cardiac Veins 835.e1

CASE STUDY 31-1

RECURRENT DEVICE-RELATED INFECTIONS Roger Carrillo  |  Chris Healy History This 63-year-old gentleman presented with tenderness, swelling, and redness over his biventricular implantable cardioverter defibrillator (BiV-ICD) pocket. He had a history of type 2 diabetes mellitus, chronic obstructive pulmonary disease, ischemic cardiomyopathy, chronic kidney disease, and ventricular tachycardia. He had previously undergone laser lead extraction for tricuspid valve endocarditis related to a dual-chamber pacemaker. That left-sided device had been extracted, and after an appropriate waiting period while on antibiotic therapy, a new system had been implanted on the right side. It had been over a year since his previous device implantation. Current Medications The patient was taking aspirin 81 mg daily, carvedilol 25 mg twice daily, lisinopril 20 mg daily, atorvastatin 80 mg daily, bumetanide 0.5 mg twice daily, dofetilide 0.25 mg twice daily, spironolactone 25 mg daily, vancomycin, cefepime, and insulin. Physical Examination Vital signs: BP 120/73 mm Hg, HR 92 bpm, temperature 98.8° F Head/neck: No evidence of jugular venous distention. Lungs/chest: Clear to auscultation and percussion bilaterally.   2 × 2 cm area of fluctuance surrounded by erythema over the ICD pocket. Heart: Nondisplaced point of maximum impulse (PMI). Regular rate and rhythm. No appreciable murmurs, rubs, or gallops. Abdomen: Soft, normoactive bowel sounds. Lower extremities: No edema. Warm and well perfused. Laboratory Data White blood cell count: 9.4 × 103/mm3 Hemoglobin: 12.5 g/dL Mean corpuscular volume: 85.6 fL Platelet count: 152 × 103/mm3 Sodium: 139 mmol/L Potassium: 4.1 mmol/L Creatinine: 1.5 mg/dL Blood urea nitrogen: 25 mg/dL Imaging Transesophageal echocardiography (TTE) revealed a left ventricular ejection fraction (LVEF) of 20%-25% and no evidence of vegetations. Hospital Course He was referred for repeat lead extraction. At the time of surgical incision, a copious amount of infected fluid was found in the pocket

Figure E31-1  A copious amount of infected fluid being expressed from the device pocket.

(Fig. E31-1). The entire system was removed, and he completed an appropriate course of antibiotic therapy. The wound culture grew Staphylococcus epidermidis. Venography of the left subclavian system performed at the time of lead extraction revealed severe central venous stenosis that was not amenable to angioplasty or stenting (Fig. E31-2). Focused Clinical Questions and Discussion Points Question: What options are available for patients with recurrent cardiac implantable electronic device (CIED)-related infection? What group of patients is particularly likely to benefit from completely epicardial CIED system implantation? Discussion: Every patient with a CIED-related infection should undergo complete removal of the entire system whenever feasible, followed by reimplantation after the infection has been cleared. Reimplantation, when indicated, should occur at a different site (e.g., the contralateral side or the abdomen).1,2 In the setting of recurrent CIED-related infections or if a patient is felt to be at particularly high risk for CIED-related infection consideration should be given to implanting a completely epicardial system. Patients with end-stage renal disease (ESRD), in particular, may benefit from completely epicardial systems. These patients are at elevated risk of bloodstream infections that may result in CIED-related infection. Furthermore, they are dependent on the patency of their central venous systems in order to receive hemodialysis, a life-prolonging therapy. Completely epicardial CIED systems may ameliorate these risks in this unique group of patients.3 Final Diagnosis CIED-related pocket infection Management He underwent successful implantation of a completely epicardial BiV-ICD system (Figs. E31-3 and E31-4). References 1. Sohail MR, Uslan DZ, Khan AH, et al: Management and outcome of permanent pacemaker and implantable cardioverterdefibrillator infections. J Am Coll Cardiol 49(18):1851–1859, 2007. 2. Chua JD, Wilkoff BL, Lee I, et al: Diagnosis and management   of infections involving implantable electrophysiologic cardiac devices. Ann Intern Med 133(8):604–608, 2000. 3. Asif A, Carrillo R, Garisto JD, et al: Epicardial cardiac rhythm devices for dialysis patients: minimizing the risk of infection and preserving central veins. Semin Dialysis 25(1):88–94, 2012.

Figure E31-2  Venography of the left subclavian system, revealing severe central venous stenosis with dilated collateral vessels.

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RT AMS POST OP

Figure E31-3  Anterior-Posterior Chest X-Ray Showing Epicardial Biventricular Cardioverter Defibrillator. Yellow arrow, defibrillation patch on posterior left ventricular wall; blue arrows, bipolar right atrial lead; black arrows, bipolar right ventricular lead; red arrows, bipolar left ventricular lead.

Figure E31-4  Lateral Chest X-Ray Showing Epicardial Biventricular Cardioverter Defibrillator. Yellow arrow, defibrillation patch on posterior left ventricular wall; blue arrows, bipolar right atrial lead; black arrows, bipolar right ventricular lead; red arrows, bipolar left ventricular lead.



CHAPTER 31  Left Ventricular Lead Placement Outside the Cardiac Veins 835.e3

CASE STUDY 31-2

CHALLENGING CORONARY SINUS LEAD IMPLANTATION Roger Carrillo  |  Chris Healy History This 59-year-old woman with type 2 diabetes mellitus, morbid obesity, and nonischemic dilated cardiomyopathy was referred for biventricular implantable cardioverter defibrillator implantation. Her electrocardiogram revealed sinus rhythm with a left-bundle branch block and a QRS duration of over 150 msec. She had previously undergone coronary angiography, which did not show any evidence of coronary artery disease. Her left ventricular ejection fraction had remained depressed (<20%) despite over 9 months of guidelinedirected medical therapy. Cardiac magnetic resonance imaging (MRI) and biopsy were both suggestive of myocarditis. Her main complaint was NYHA class III dyspnea on exertion. Current Medications The patient was taking carvedilol 6.25 mg twice daily, lisinopril 5 mg daily, furosemide 80 mg daily, spironolactone 25 mg daily, rivaroxaban 20 mg daily, and metformin 1,000 mg twice daily. Physical Examination BP/HR: 102/58 mm Hg/62 bpm Head/neck: No evidence of jugular venous distention. Lungs/chest: Clear to auscultation and percussion bilaterally. Heart: Laterally displaced point of maximum impulse (PMI). Regular rate and rhythm. Grade III/VI holosystolic murmur. Abdomen: Soft, obese, normoactive bowel sounds. Lower extremities: No edema. Warm and well perfused. Laboratory Data Hemoglobin: 10.8 g/dL Mean corpuscular volume: 88.1 fL Platelet count: 248 × 103/mm3 Sodium: 137 mmol/L Potassium: 4.9 mmol/L Creatinine: 1.2 mg/dL Blood urea nitrogen: 40 mg/dL Electrocardiogram Her presenting electrocardiogram (Fig. E31-5) showed sinus rhythm with a left bundle branch block and a QRS duration of 170 msec. Echocardiogram Her echocardiogram showed moderate left ventricular (LV) dilation with severely reduced systolic function (ejection fraction 15%-20%). There was also evidence of severe mitral regurgitation. Hospital Course She underwent implantation of an atrial lead and a right ventricular defibrillation lead. During attempted implantation of the coronary

sinus lead, a stenosis in the target branch (Fig. E31-6)   was found, which precluded advancement of the lead to an acceptable position. Balloon venoplasty was attempted (Fig. E31-7). In spite of this, successful transvenous lead placement was not possible. Focused Clinical Questions and Discussion Points Question: What are the available options for epicardial LV lead placement among patients who require cardiac resynchronization therapy and have failed transvenous lead implantation? What are the risks/benefits of these options? Discussion: Surgical epicardial lead placement has been observed to have similar outcomes when compared with transvenous coronary sinus lead placement.1,2 The available approaches for epicardial LV lead placement include full left-sided thoracotomy, limited left-sided anterior thoracotomy, thoracoscopic lead placement, and an open-chest approach. The open-chest approach should be reserved for patients who are having open-heart surgery. Traditional full left-sided thoracotomy should be avoided whenever possible due to the significant and typically unnecessary attendant morbidity. Limited left-sided anterior thoracotomy offers the advantages of potentially superior LV lead localization and shorter procedure time, but   it is associated with significant postoperative discomfort. A thoracoscopic approach offers the benefit of less postoperative pain but may be associated with longer procedure times, particularly among inexperienced operators.3 In addition, mapping of the lateral left ventricular wall to identify the site of latest activation is not possible with a thoracoscopic approach. Management Epicardial lead implantation was recommended. This was achieved via a minimally invasive thoracoscopic approach (Fig. E31-8). The patient did well postoperatively with only minimal pain. Chest radiography showed the lead to be positioned on the lateral wall of the left ventricle (Fig. E31-9). References 1. Ailawadi G, LaPar DJ, Swenson BR, et al: Surgically placed left ventricular leads provide similar outcomes to percutaneous leads in patients with failed coronary sinus lead placement. Heart Rhythm 6:619–625, 2010. 2. Mair H, Sachweh J, Meuris B, et al: Surgical epicardial left ventricular lead versus coronary sinus lead placement in biventricular pacing. Eur J Cardiothorac Surg 27:235–242, 2005. 3. Nelson KE, Bates MG, Turley AJ, et al: Video-assisted thoracoscopic left ventricular pacing in patients with and without previous sternotomy. Ann Thorac Surg 95(3):907–913, 2013.

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Figure E31-5  Presenting electrocardiogram.

Figure E31-6  Coronary sinus venography showing the area of stenosis (arrow), which prevented distal advancement of the lead to an acceptable position.

Figure E31-7  Attempted balloon venoplasty of the area of stenosis in the coronary sinus.



CHAPTER 31  Left Ventricular Lead Placement Outside the Cardiac Veins 835.e5

LV

Figure E31-8  Magnified Thoracoscopic View of Epicardial Lead Implantation. The reflected pericardium is seen at the bottom of the image (black arrow). The epicardial lead tip (7 mm × 9 mm) is seen sutured to the lateral wall of the left ventricle (LV) between two obtuse marginal branches (white arrows) of the left circumflex coronary artery.

Figure E31-9  Posterior-anterior and lateral chest x-rays following epicardial left ventricular lead (arrows) implantation for cardiac resynchronization therapy.

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However, the possibility of being able to optimize LV lead placement is of greater importance, strongly supporting epicardial lead placement. LIMITED LEFT-SIDED ANTERIOR THORACOTOMY This approach should include epidural and/or intercostal analgesia to minimize postoperative pain. The procedure is facilitated if a doublelumen endotracheal tube is used, allowing deflation of the left lung. Because heart location varies considerably, the difficult part of this procedure is to choose the optimal intercostal space to gain direct access to the electrically interesting LV lateral wall area. Selecting the correct intercostal space is facilitated by palpation of the ictus preoperatively. Having found the right intercostal level, the incision can usually be very limited, especially because the LV is often located in direct contact with the thoracic wall in this group of patients. Cardiac access can sometimes be gained even without opening the left pleural space. A small cross-formed incision of the pericardium, over the lateral aspect of the LV, is performed after identification of the phrenic nerve. Optimal lead position can be found by mapping with a separate, passive fixation lead. This lead is systematically moved to different positions measuring the sensed R-R interval. The mapping lead is connected to the ventricular channel, and the RV lead to the atrial channel of a pacing systems analyzer (PSA). The measured R-R time delays are documented on a nine-square map reflecting the lateral aspect of the LV. The lead position providing the longest R-R interval varies considerably from patient to patient, not only reflecting RV lead position (usually not variable due to previous implantation), but also reflecting variable depolarization patterns. Checking response by biventricular pacing and recording a narrow QRS complex is part of the procedure. Subsequently, a permanent bipolar lead is implanted at the location of the longest R-R interval, the mapping results are confirmed, and the pacing parameters measured. The lead position rarely needs to be modified due to high pacing threshold or inadequate impedance. Active or passive permanent leads can be used. Modern bipolar screw-in leads are preferred, because they are easier to use than passive stitch-on leads when a limited thoracotomy approach is used. These active fixation leads have a thin screw, contain steroid, and have shown excellent long-term function, very different from that of old epicardial screw-in leads that often suffered from high pacing thresholds over time.18,19 However, the only epicardial screw-in leads available in the U.S. are those without steroids. The only epicardial leads with steroids currently available in the U.S. are the stich-on leads. Implantation of two leads, placed in the same area but clearly separated, is recommended to avoid another thoracotomy should the connected lead fail over time. The backup lead is capped in the device pocket and can be connected when needed. Finally, many CRT patients have undergone previous coronary artery bypass graft (CABG) surgery and have pericardial adhesions and functional grafts. This is not an obstacle for epicardial lead placement but may require some dissection to free the lateral LV wall. Grafts rarely are in the way of mapping or lead implantation. In summary, compared with transvenous lead placement, the limited thoracotomy approach for epicardial LV lead implantation involves the risks associated with general anesthesia (GA) and surgery, plus postoperative discomfort including that of pleural drainage. This approach offers the great advantage of potentially better LV lead placement and sometime shorter procedure time than CS implantations. THORACOSCOPIC LEAD PLACEMENT Present video-assisted thoracoscopic techniques are well established, involve limited morbidity, and provide the instruments needed for epicardial lead placement. GA, a double-lumen endotracheal tube, and pleural drainage are still needed. A standard three-port access is used. After deflation of the left lung and opening of the pericardium, electrical mapping is performed as previously described to find the point of latest activation. The use of a commercial screw-in lead mounted on a

special tool supplied with the lead facilitates the permanent lead implantation considerably because the tool can be used through a port of adequate size. Two LV leads are placed if possible. The leads are brought out via one of the port incisions and then tunneled subcutaneously to a standard left sided subclavicular device pocket. One of the other small port incisions is used for the pleural drainage tube. Compared with the minithoracotomy approach, this method offers less morbidity but is more time consuming. Opening of the pericardium to gain overview, freeing the lateral LV wall (especially when adherence is present), performing the essential mapping as previously described, and implanting one or two leads can be challenging before enough experience is gained.20 Robotic lead placement is another version of this approach, offering few advantages, because systematic mapping will not be facilitated. SUBXIPHOID LEAD PLACEMENT One of the most interesting approaches to epicardial lead placement is the subxiphoid. This method avoids an intercostal approach, thereby reducing pain and the subsequent need for epidural analgesia and drainage because the pleura is not entered. General anesthesia can be avoided, and the device can be implanted in the epigastrium, if preferred. Presently, the approach involves a small transverse incision and freeing the subcostal muscles from the lower rib. After dissection of the supradiaphragmatic soft tissue, the pericardium is easily reached and opened. Before the arrival of transvenous implantable cardioverterdefibrillator (ICD) treatment, defibrillation patches and sensing leads were successfully implanted by a subxiphoid or subcostal approach to avoid sternotomy. Subxiphoid leads can either be stitched on the apical part of the LV or implanted freely on the lateral aspect of LV using a steerable tool carrying a screw-in lead. Although mapping is possible, one present drawback is the difficulty to implant an LV lead of any type at the identified point of latest activation without visual control. Visual control is useful not only for checking optimal lead position based on mapping, but also for avoiding damage to coronary arteries during lead implantation. In daily clinical practice the pericardium is often punctured by a subxiphoid approach for fluid aspiration or drainage. This often involves the introduction of a guidewire and sometimes a drainage tube via an introducer. A similar approach could be used for epicardial lead implantation. Such an approach has great potential because it would be associated with very limited morbidity and could be performed with just local analgesia and sedation, while also allowing mapping and optimal lead placement. It would require a workstation through which a steerable, lead carrying tool could be introduced, allowing both mapping and lead placement and possibly also visual control. Steerable tools carrying screw in-leads are available but are presently too big for use through an introducer. Safer and simpler methods for pericardial puncture are generally needed and would also make subxiphoid epicardial lead placement safer and more attractive. OPEN-CHEST APPROACH During open-heart procedures epicardial LV lead implantation is usually uncomplicated. Either screw-in or a stich-on leads can be used, the choice is often related to the space available and the angle of implantation. Leads can be brought out to a standard left sided subclavicular device pocket either between ribs or by routing the leads by the xiphoid region and then subcutaneously to the pocket. The latter approach is preferred because leads can be cut in healthy tissue, avoiding extraction should a pocket infection occur. Implantation of epicardial LV leads should always be considered at the time of open-heart surgery, not only in patients qualified for CRT treatment, but also in potential cases. The complication risk and cost of doing so are low. Two LV leads should be implanted, one capped in the device pocket, should lead failure develop. A limitation with the concomitant approach to LV implantation is that electrical mapping is difficult to achieve when on bypass, and sometimes also after weaning off bypass,



CHAPTER 31  Left Ventricular Lead Placement Outside the Cardiac Veins

because the heart may not tolerate the manipulation needed to gain space necessary for mapping.

LEFT VENTRICULAR ENDOCARDIAL PACING DELIVERY ROUTES FOR “CONVENTIONAL” PACING LEADS Transaortic Route There is limited experience with this approach. It is inherently complicated by the concerns that attend passage of a pacing lead across both aortic and mitral valves. This has important consequences particularly for aortic valve function, which is likely to be less forgiving of the mechanical consequences of placing a pacing lead body across the valve cusps than is the mitral valve. In both instances there is concern about the potential for persisting valvular dysfunction due to interference with normal valve function and the potential for damage inflicted on the valve structure as a consequence of mechanical disruption by valve movement against the lead body. Currently, there is no clinical approach employed for transaortic valve pacing, although there is report of animal experience21 and case reports of accidental short-term pacing.22 This procedural approach is therefore not considered further. Transapical Left Ventricular Endocardial Pacing Direct LV wall pacing was first reported many years go. It has been used for the purposes of diagnostic cardiac catheterization23 when pressure and angiographic data were considered to be of such clinical importance as to warrant this approach in the context of a “protected” left ventricle—usually due to the presence of a mechanical aortic valve, when passage of an intracardiac catheter device across that valve would be at best hazardous and likely catastrophic. There is very limited clinical experience with this approach, which appears to offer significant procedural challenges.24 That same route has been used for the purposes of catheter ablation procedures and passage of a pacing lead to the LV endocardial surface. Transventricular Septal Approach LV endocardial pacing has been reported using a direct interventricular septal puncture approach.25 This procedure requires use of a powered technology (commonly radiofrequency energy) to burn through the septum to achieve direct ventricular access. The approach has the advantage of not requiring passage of a lead across the mitral valve (see transatrial-septal approach below), but there may be concern for potential for ventricular damage, either directly or as a consequence of myocardial vasculature disruption. Furthermore, the pacing lead may be exposed to significant challenge due to myocardial contraction impacting on structural integrity. Overall this approach is likely to be much less attractive than LV endocardial pacing lead access achieved via the interatrial septum. Transatrial Septum Approach Accidental atrial transseptal pacing has been reported, and it is also shown that lead extraction from this route can be performed safely.26 As the LV pacing leads are part of an atrial/RV pacing system, the implanted device will reside at a prepectoral implant site. Therefore the final lead route must track from the superior approach (cephalic, axillary, jugular, or direct subclavian venous access), as is commonly required for conventional right heart endocardial pacing. However, because the LV endocardial lead must cross the interatrial septum, the transseptal puncture performed to achieve this can be executed using an approach from the groin27,28 or by direct superior transseptal puncture using modified equipment that allows transseptal puncture from above. Transseptal Puncture: Inferior Approach Atrial transseptal puncture is most commonly performed from an inferior approach for the purposes of ablation and other procedures

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that require access to the left atrium. The reasons are multiple: the technique is most often employed in interventional procedures when there is no clinical plan to leave any indwelling lead system; most procedures are performed with right or sometimes left groin access to the venous system. Technical approaches and technologies are designed for groin venous access; the anatomy of the interatrial septum is such that the inferior approach allows operators to orientate themselves more easily with the catheters approach to the septum from the inferior vena cava (IVC), relative to other cardiac structures, which are at risk of damage—particularly the aortic root. Because of their underlying disease processes, patients receiving CRT often have significant changes in atrial and atrial septum dimensions in addition to “mechanical properties” of the interatrial septum, when compared with those encountered with structurally normal hearts undergoing routine catheter ablation procedures. This should be borne in mind by operators who are likely to feel that the anatomic relationships and technology affordances are different from their usual experience. Having achieved access to the left atrium with a transseptal puncture (using a conventional needle or radiofrequency [RF] needle), a guidewire is passed to left atrium, in turn allowing passage of a delivery catheter system into the left atrium. This can then be used to pass a pacing lead into the left atrium, which in turn is manipulated in customary fashion into the LV and fixed. However, the proximal (device-connecting) end of the fixed pacing lead now has to be passed to the superior venous system and externalized for connection to a prepectoral implanted device location. Authors have described several technical approaches comprising use of a snare or similar technology. One approach is to snare the initial guidewire that has been passed to the left atrium and to externalize it. This results in the guidewire being externalized at a superior access site having initially been passed into left atrium using the groin approach. All approaches offer procedural challenges29,30 and may carry important infection risk related to the groin access site, giving rise to contamination of the superior access and device implant site. Transseptal Puncture: Direct Superior Approach Recognizing the challenges of the inferior approaches, tools have been developed that allow direct transseptal puncture using a superior approach. This approach was first reported using a modified Brockenborough needle.31 However, achieving correct orientation of the transseptal needle relative to the interatrial septum is challenging. As with the inferior approach, dilation of the cardiac chambers as a consequence of the underlying disease process results in considerable variation in the properties of the interatrial septum. Such features make it difficult to establish a stable superior platform for passage of the LV endocardial pacing lead delivery system across the septum, into the left atrium, and then the left ventricle. A purpose-designed system has been trialed and reported by Medtronic (Minneapolis, MN) for LV endocardial pacing abstract form (the Alternative Site Cardiac Resynchronization [ALSYNC] study).32 Figures 31-1 to 31-8 illustrate placement of a LV endocardial pacing lead by a superior atrial transseptal approach. Key to this system is use of a flexible RF transseptal needle, which is modified to adopt a pigtail conformation as it crosses the interatrial septum. This reduces the risk of aortic root puncture via the left atrium—a life-threatening complication of transseptal puncture. A steerable guide catheter is used to orientate the delivery system towards the atrial septum and ideally to tent the septum as seen under either intracardiac echo or transesophageal echo control. The steerable guide catheter is therefore the platform used for transseptal puncture, although that catheter itself always remains on the right heart side of the interatrial septum. Transseptal puncture is performed using a dilator through which the pigtail RF needle passes. Under echo and fluoroscopy control, the passage of the pigtail conformation RF needle is monitored as it passes into the left atrium. The dilator is then passed over the pigtail wire into

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Figure 31-1  Transesophageal echocardiogram showing tenting of interatrial septum by steerable guide catheter (white arrow). Figure 31-4  Passage of lead-delivery catheter through guide catheter and over RF pigtail needle across interatrial septum (white arrow) and into left ventricular cavity on fluoroscopy (40-degree left anterior oblique) (see text for description).

Figure 31-2  Guide catheter (white arrow) on fluoroscopy (40-degree left anterior oblique) apposed to interatrial septum on right side.

Figure 31-5  Passage of 4-French pacing lead through lead-delivery catheter through guide catheter across interatrial septum (white arrow) (pigtail RF needle removed) and into left ventricular cavity on fluoroscopy (40-degree left anterior oblique) (see text for description).

Figure 31-3  Passage of RF pigtail needle across interatrial septum (white arrow) on fluoroscopy (40-degree left anterior oblique) (see text for description).

the left atrium, but ensuring that the pigtail RF needle always acts as a guidewire in order to avoid any inadvertent left atrial wall puncture. The “dual” role of the RF “needle” is to act both as the transseptal puncture needle and as a guidewire that allows orientation of the delivery system into the left ventricle. Thus the pigtail RF needle is passed to left ventricle. Thereafter the pacing lead delivery catheter is passed to the left ventricle using both the dilator or/and the RF needle as a “monorail” system. In exceptional circumstances, the orientation and mechanism for the delivery system are such that the RF needle does not provide a sufficiently strong monorail. In that event the RF pigtail needle can be changed to a conventional extra-strength guidewire the operator chooses, providing a more robust monorail platform for the delivery catheter to enter the left ventricle. Once the delivery catheter has entered the left ventricle, then the monorail system can be withdrawn, leaving the delivery catheter



CHAPTER 31  Left Ventricular Lead Placement Outside the Cardiac Veins

Figure 31-6  Fixation of 4-French pacing lead onto left ventricular cavity endocardial surface (white arrow) on fluoroscopy (40-degree left anterior oblique) (see text for description).

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Figure 31-8  Postprocedure radiograph.

This is achieved by the use of “slitting tools” as employed in conventional CRT delivery. The order of catheter removal (there are three sheaths to remove) will be determined by operator preference. Best practice may be to first remove the standard “split-able” sheath used for venous access, followed by removal of the left ventricular placement lead catheter, and finally, the platform steerable catheter that is seated on the RA aspect of the interatrial septum. Best practice is to reconfirm appropriate LV pacing lead parameters at this stage. Thereafter, the procedure is completed by attaching the LV pacing lead to the chosen CRT pulse-generating implant device and implanting the device into a prepectoral space fashioned for the purpose in the standard fashion. Anticoagulation and Stroke Risk

Figure 31-7  Final position of 4-French pacing lead onto left ventricular cavity endocardial surface (white arrow) on fluoroscopy (40-degree left anterior oblique) and after removal of delivery system (see text for description).

lumen free for ingress of the “Select Secure” (Medtronic lead 6093, Minneapolis, MN) pacing lead. At the operator’s discretion the delivery catheter can be easily orientated to any placement site over the landscape of the LV endocardial surface to access an optimal LV endocardial pacing site according the criteria adopted by the operator for the achievement of optimal cardiac resynchronization therapy. Fixation of the Select-Secure lead is achieved by torsion of the entire lead body (it is a lumen-free, nonstyle driven lead with a fixed external fixation screw). Six clockwise turns of the lead shaft are required to achieve stable fixation. At this juncture standard pacing lead assessments are performed. Having selected the optimal LV endocardial pacing site and having confirmed satisfactory pacing parameters, the delivery system is now removed.

There remains the risk of device-related thromboembolism during and in the long term after the implant procedure.33-36 Heparinization is commenced at the time that left atrial access is gained by passage of the pigtail needle, which forms the platform/dilator catheter assembly into the left atrium. An activated clotting time (ACT) greater than 300 is the target anticoagulation level for the duration of the procedure and a heparin pump infusion can be used to maintain that level with repeated ACT checks (at 15 to 20 minute intervals). The risk of pacing lead thromboembolism persists after the initial implant event and may particularly relate to the interface between the pacing electrodes and the polyurethane lead body. Thus anticoagulation aiming for an international normalized ratio (INR) of between 2.5 and 3.5 was used in the ALSYNC study and according to other reports of medium-term follow-up37,38 is highly efficacious in preventing thromboembolic events. It must be noted that the patient population that receives CRT is a high-risk stroke group outside of any issue that pertains to intracardiac devices. Thus there is a high burden of atrial fibrillation in this patient population and spontaneous stroke occurrence in the context of heart failure. The patient population that was recruited to the ALSYNC population has no direct comparisons for stroke risk because of their notable a priori stroke risk and morbidity. Life-long anticoagulation is mandatory in these patients to reduce stroke risk. There is minimal experience of the use of novel anticoagulation issues, but given the poor performance of these agents in the prevention of thromboembolic stroke in mechanical valve recipients, for the time being, warfarin must be considered the only suitable anticoagulation drug. The use of heparin and warfarin for thromboembolic prevention obviously requires that the operator pays strict attention to achieving excellent hemostasis within the operative field.

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SECTION 4  Implantation Techniques

Postoperative Management For most implants, standard procedures are followed for the pre­ vention of implant-related infection and for optimization of implant pacing parameters and ventricular arrhythmia management parameters. LEFT VENTRICULAR ENDOCARDIAL PACING USING DIRECTLY FIXED INDEPENDENT ELECTRODES This technology has not been made commercially available and is still undergoing evaluation with clinical studies.39 It comprises novel pacing electrodes of very small size and equipped with miniaturized voltage/current generating circuitry capable of generating a pace-evoked response at the endocardial-electrode interface. The energy that enables pulse generation is received via an ultrasound pulse delivered from a power generator implanted subcutaneously in the thoracic surface and in close proximity to the heart. For appropriate LV pace generation timing and for achievement of CRT, the patient also receives a conventional endocardial RV pacing system. Initial evaluations show promise, although technical hurdles remain with respect to the delivery of the electrodes to LV and battery longevity of the power generating system.

SUMMARY LEFT VENTRICULAR EPICARDIAL PACING—SURGICAL APPROACH Direct/surgical epicardial placement of LV leads as part of CRT treatment offers the opportunity of placing leads freely on the lateral wall, avoiding the anatomic restrictions of CS lead placement. The

possibility of unrestricted lead position offers the opportunity to find the lead position providing optimal response. This position is often the point of latest activation. One method to identify this small area is to map for the longest sensed R-R interval. Presently available epicardial implantation approaches involve limited morbidity and are therefore attractive alternatives to CS mediated pacing. These epicardial implantation approaches have advantages and disadvantages; which one to choose depends not only on patient factors such as body mass, but also on available implantation competence. The potential of finding the lead position delivering the most effective resynchronization by stimulation at the point of latest activation should be the guiding principle when choosing LV lead implantation approach for a specific patient. This may increasingly be a direct epicardial approach. Left Ventricular Endocardial Pacing Direct LV endocardial pacing can be achieved using a range of approaches for delivery of either conventional or novel pacing electrode technologies. LV pacing using the superior atrial transseptal route has the largest supporting evidence base and is known to be a safe approach given the outcome of a major trial with long-term follow-up. This does not exclude the possibility that alternative approaches or novel technologies may have clinical value. Whether LV endocardial pacing has clinical superiority compared with conventional LV epicardial pacing via the CS needs to be tested in appropriately designed studies. Systemic-ventricular pacing may also be a useful treatment in some niche populations.40 However, it represents an alternative approach to surgical epicardial pacing in patients in whom conventional CS-delivered CRT cannot be achieved, may offer an alternative and improved therapeutic strategy to nonresponders to conventional CRT, and with technology improvements could become the optimal pacing approach for CRT.

REFERENCES 1. McAlister FA, Ezekowitz J, Hooton N, et al: Cardiac resynchronization therapy for patients with left ventricular systolic dysfunction: a systematic review. JAMA 297(22):2502–2514, 2007. 2. Polasek R, Skalsky I, Wichterle D, et al: High-density epicardial activation mapping to optimize the site for video-thoracoscopic left ventricular lead implant. J Cardiovasc Electrophysiol 25(8): 882–888, 2014. 3. Derval N, Bordachar P, Lim HS, et al: Impact of pacing site on QRS duration and its relationship to hemodynamic response in cardiac resynchronization therapy for congestive heart failure. J Cardiovasc Electrophysiol 25(9):1012–1020, 2014. 4. Fatemi M, Le Gal G, Blanc JJ, et al: The use of epicardial electrogram as a simple guide to select the optimal site of left ventricular pacing in cardiac resynchronization therapy. Cardiol Res Pract 2011:956062, 2011. 5. Tedrow UB, Stevenson WG, Wood MA, et al: Activation sequence modification during cardiac resynchronization by manipulation of left ventricular epicardial pacing stimulus strength. Pacing Clin Electrophysiol 30(1):65–69, 2007. 6. Blendea D, Singh JP: Lead positioning strategies to enhance response to cardiac resynchronization therapy. Heart Fail Rev 16(3):291–303, 2011. 7. Rickard J, Johnston DR, Price J, et al: Reverse ventricular remodeling and long-term survival in patients undergoing cardiac resynchronization with surgically versus percutaneously placed left ventricular pacing leads. Heart Rhythm 12(3):517–523, 2015. 8. Jais P, Douard H, Shah DC, et al: Endocardial biventricular pacing. Pacing Clin Electrophysiol 21(11 Pt 1):2128–2131, 1998. 9. Jais P, Takahashi A, Garrigue S, et al: Mid-term follow-up of endocardial biventricular pacing. Pacing Clin Electrophysiol 23(11 Pt 2):1744–1747, 2000. 10. Morgan JM, Scott PA, Turner NG, et al: Targeted left ventricular endocardial pacing using a steerable introducing guide catheter and active fixation pacing lead. Europace 11(4):502–506, 2009. 11. Faris OP, Evans FJ, Dick AJ, et al: Endocardial versus epicardial electrical synchrony during LV free-wall pacing. Am J Physiol Heart Circ Physiol 285(5):H1864–H1870, 2003. 12. Garrigue S, Jaïs P, Espil G, et al: Comparison of chronic biventricular pacing between epicardial and endocardial left ventricular stimulation using Doppler tissue imaging in patients with heart failure. Am J Cardiol 88(8):858–862, 2001. 13. Bracke FA, van Gelder BM, Dekker LR, et al: Left ventricular endocardial pacing in cardiac resynchronisation therapy: moving from bench to bedside. Neth Heart J 20(3):118–124, 2012. 14. Derval N, Steendijk P, Gula LJ, et al: Optimizing hemodynamics in heart failure patients by systematic screening of left ventricular pacing sites: the lateral left ventricular wall and the coronary

sinus are rarely the best sites. J Am Coll Cardiol 55(6):566–575, 2010. 15. Spragg DD, Dong J, Fetics BJ, et al: Optimal left ventricular endocardial pacing sites for cardiac resynchronization therapy in patients with ischemic cardiomyopathy. J Am Coll Cardiol 56(10):774–781, 2010. 16. Bordachar P, Grenz N, Jais P, et al: Left ventricular endocardial or triventricular pacing to optimize cardiac resynchronization therapy in a chronic canine model of ischemic heart failure. Am J Physiol Heart Circ Physiol 303(2):H207–H215, 2012. 17. Gold MR, Rashba EJ: Left ventricular endocardial pacing: don’t try this at home. Pacing Clin Electrophysiol 22(11):1567–1569, 1999. 18. Buiten MS, van der Heijden AC, Klautz RJ, et al: Epicardial leads in adult cardiac resynchronization therapy recipients: a study on lead performance, durability, and safety. Heart Rhythm 12(3):533– 539, 2014. 19. Burger H, Kempfert J, van Linden A, et al: Endurance and performance of two different concepts for left ventricular stimulation with bipolar epicardial leads in long-term follow-up. Thorac Cardiovasc Surg 60(1):70–77, 2012. 20. Nelson KE, Bates MG, Turley AJ, et al: Video-assisted thoracoscopic left ventricular pacing in patients with and without previous sternotomy. Ann Thorac Surg 95(3):907–913, 2013. 21. Reinig M, White M, Levine M, et al: Left ventricular endocardial pacing: a transarterial approach. Pacing Clin Electrophysiol 30(12):1464–1468, 2007. 22. Liebold A, Aebert H, Muscholl M, Birnbaum DE: Cerebral embolism due to left ventricular pacemaker lead: removal with cardiopulmonary bypass. Pacing Clin Electrophysiol 17(12 Pt 1): 2353–2355, 1994. 23. Morgan JM, Gray HH, Gelder C, Miller GA: Left heart catheterization by direct ventricular puncture: withstanding the test of time. Cathet Cardiovasc Diagn 16(2):87–90, 1989. 24. Kassai I, Mihalcz A, Foldesi C, et al: A novel approach for endocardial resynchronization therapy: initial experience with transapical implantation of the left ventricular lead. Heart Surg Forum 12(3):E137–E140, 2009. 25. Betts TR, Gamble JH, Khiani R, et al: Development of a technique for left ventricular endocardial pacing via puncture of the interventricular septum. Circ Arrhythm Electrophysiol 7(1):17–22, 2014. 26. de Cock CC, van Campen CM, Kamp O, Visser CA: Successful percutaneous extraction of an inadvertently placed left ventricular pacing lead. Europace 5(2):195–197, 2003. 27. van Gelder BM, Houthuizen P, Bracke FA: Transseptal left ventricular endocardial pacing: preliminary experience from a femoral approach with subclavian pull-through. Europace 13(10):1454–1458, 2011.

28. Nuta B, Lines I, MacIntyre I, Haywood GA: Biventricular ICD implant using endocardial LV lead placement from the left subclavian vein approach and transseptal puncture via the transfemoral route. Europace 9(11):1038–1040, 2007. 29. Lau EW: Yoked catheter positioning in transseptal endocardial left ventricular lead placement. Pacing Clin Electrophysiol 34(7):884– 893, 2011. 30. Elencwajg B, López Cabanillas NL, Cardinali EL, et al: The Jurdham procedure: endocardial left ventricular lead insertion via a femoral transseptal sheath for cardiac resynchronization therapy pectoral device implantation. Heart Rhythm 9(11):1798– 1804, 2012. 31. Ji S, Cesario DA, Swerdlow CD, Shivkumar K: Left ventricular endocardial lead placement using a modified transseptal approach. J Cardiovasc Electrophysiol 15(2):234–236, 2004. 32. ALSYNC: LV endocardial pacing could help in CRT nonresponse. Medscape 2014. 33. McManus DD, Mattei ML, Rose K, et al: Inadvertent lead placement in the left ventricle: a case report and brief review. Indian Pacing Electrophysiol J 9(4):224–228, 2009. 34. Sahin T, Kilic T, Celikyurt U, et al: Asymptomatic malposition of pacemaker lead associated with thrombus. Clin Res Cardiol 98(1):71–73, 2009. 35. Scott PA, Barry J, Turner NG, Morgan JM: Inadvertent left ventricular pacing through the pericardium. Pacing Clin Electrophysiol 32(10):e9–e10, 2009. 36. Reising S, Safford R, Castello R, et al: A stroke of bad luck: left ventricular pacemaker malposition. J Am Soc Echocardiogr 20(11):1316.e1–1316.e3, 2007. 37. Rademakers LM, van Gelder BM, Scheffer MG, Bracke FA: Midterm follow up of thromboembolic complications in left ventricular endocardial cardiac resynchronization therapy. Heart Rhythm 11(4):609–613, 2014. 38. Pasquie JL, Massin F, Macia JC, et al: Long-term follow-up of biventricular pacing using a totally endocardial approach in patients with end-stage cardiac failure. Pacing Clin Electrophysiol 30(Suppl 1):S31–S33, 2007. 39. Lee KL, Tse HF, Echt DS, Lau CP: Temporary leadless pacing in heart failure patients with ultrasound-mediated stimulation energy and effects on the acoustic window. Heart Rhythm 6(6):742–748, 2009. 40. Scott PA, Veldtman GR, Yue AM, Morgan JM: Permanent transvenous left ventricular endocardial pacing in a patient with univentricular atrioventricular connection. Congenit Heart Dis 6(5):475–478, 2011.