Implantation

As with most things in life, preparation is everything; that is, one must “plan the work, then work the plan.” The determination to embark on pacemaker implantation includes the assumption that the implanter has had the appropriate degree of training, has maintained proficiency in this area, and understands the specific indications for a particular procedure as delineated in the ACC/AHA/HRS guidelines for device implantation. The maintenance of a minimum procedural volume is essential, and, indeed, the number of implants performed by an individual is inversely related to the development of complications at the time of implantation. In addition, preparation entails anticipation of all the resources and personnel required to perform the operation, including a sterile operating arena (whether operating room or catheterization laboratory), standard operating room instruments, pacemaker leads and generators, corresponding pacer programmers, pacer system analyzers, anesthesia/sedation, fluoroscopy, and emergency equipment (e.g., pericardiocentesis sets). The presence of an experienced nurse or technician who can make the necessary threshold determinations is also indispensable. The role of the “pacemaker manufacturer’s representative” in this regard remains highly controversial and continues to raise both quality assurance issues and ethical concerns.

Deciding on an operating strategy is crucial. This is especially true in complicated cases—patients with pre-existing pacer or defibrillator systems with pacer dependence; patients with congenital cardiovascular abnormalities such as persistent superior vena cava syndrome with previous demonstration of subclavian vein thrombosis; or patients in whom individualization of therapy dictates something “special” (e.g., contralateral placement in a mastectomy patient, placement of the device as a function of the patient’s left-handedness or right-handedness, or cosmetic concerns necessitating a submammary implant).

The use of antibiotic prophylaxis before implantation has long been debated. Meta-analysis, however, suggests that prophylaxis may, indeed, be very important in minimizing device-related infections. Generally, an antistaphylococcal antibiotic is administered “on-call” to the procedure with continuation of this antibiotic for 24 hours following the implantation. The site of peripheral intravenous placement—this should be ipsilateral to the anticipated site of implant so as to allow for dye injection and radiographic imaging of central venous anatomy in cases where percutaneous subclavian or cephalic vein access is difficult—should also be considered preoperatively. The anticoagulated patient poses a particular challenge both preoperatively and perioperatively. Warfarin (Coumadin) is generally withdrawn to achieve an international normalized ratio (INR) of less than 2; cephalic cutdown and strict hemostasis are encouraged; and warfarin is resumed postoperatively, preferably without the adjunct of intravenous heparin or enoxaparin (with which significant pocket hematomas have occurred). Some have demonstrated, however, that implantation may take place without withholding warfarin and without untoward bleeding problems.

The choice (and number) of leads must also be considered. Passive-fixation leads are typically associated with less elevation in acute threshold level, but active-fixation leads may be selected when potential dislodgment is a significant concern. This might be anticipated, for example, in cases of smooth-walled dilated right ventricles, amputated atrial appendages in patients having undergone earlier open-heart surgery, or right ventricular outflow tract lead positioning. In addition, active-fixation leads may be more easily removed in the unlikely event that extraction is a future consideration. Pacing configuration (unipolar vs. bipolar) is also an important issue to contemplate. On the one hand, unipolar leads are typically smaller in diameter and easier to introduce; in many cases, two unipolar leads may be introduced primarily through a single venotomy or even through a single peel-away introducer. However, unipolar systems have many potential disadvantages, including myopectoral stimulation, myopotential inhibition, and sensing of unipolar spikes by simultaneously implanted defibrillators. On the other hand, bipolar lead systems have had a number of associated advisories related to insulation degradation and subclavian crush syndrome. Compatibility of the selected lead(s) with the designated pulse generator must be ensured.

Epicardial or subxiphoid placement of pacer systems is typically reserved for those individuals who cannot undergo effective pacing via the transvenous route (e.g., a patient who has a mechanical tricuspid valve replacement) or who are simultaneously undergoing thoracotomy for other reasons. Limited surgical approaches using a trans-atrial implantation technique have also been described.

Transvenous pacing is usually the preferred route, with use of the cephalic vein, the subclavian vein, or the axillary vein; it is rare to employ the external or internal jugular veins. Identification of a reasonably sized brachial or antecubital vein by placing a tourniquet around the arm is a good predictor that the patient will have a usable cephalic vein more proximally. After meticulous preparation, draping, and administration of local anesthesia, a circumlinear incision is made; dissection follows down to the delto-pectoral fat pad, beneath which courses the cephalic vein (Figure 32-1). Many implanters choose to access the subclavian vein percutaneously before making such an incision, in the belief that the anatomies of the clavicle and the first rib are better appreciated “from the outside.” Nothing, however, precludes using the subclavian approach from within the incision if the cephalic vein is not encountered. The distinct advantages to looking for the cephalic vein first are as follows: (1) It avoids the potential risk of pneumothorax, subclavian artery puncture associated with attempts at subclavian vein puncture, or both; (2) it may avoid trauma to the lead incurred in the subclavian crush syndrome or associated with the peel-away introducer technique; (3) it provides yet another avenue of access not available to those implanters who are accustomed to only the subclavian puncture technique, and (4) in cases of subsequent revision, it allows the use of an unused subclavian vein. Ligatures are applied proximally and distally to the site of the venotomy (Figure 32-2). It is particularly important to tie off the distal ligature (usually with 3-0 silk) before introducing the lead to prevent significant back-bleeding should a small cephalic vein avulse with manipulation. Vein lifts that are typically supplied with the pacemaker electrodes can be abrasive; the author prefers to use a curved iris forceps. The lead should be visually inspected before introducing it to ensure that no defects are present at the very outset before manipulation.

Figure 32-1 Isolation of cephalic vein.

Figure 32-2 Insertion of lead through venotomy in cephalic vein.

Often a venotomy through the cephalic vein will accommodate both atrial and ventricular leads. Occasionally, only one (or neither) may be introduced primarily, because the vein is either too small or tortuous. In such cases, one may consider introducing a guidewire through the cephalic vein and then using a peel-away introducer technique through the cephalic vein to introduce one or both leads (Ong-Barold technique; see Figures 32-3 and 32-4). Again, great care should be taken while advancing the introducer (use of a Gerard forceps to raise the flap of the venotomy may be helpful here) to avoid avulsing the cephalic vein, and fluoroscopic visualization of the advancing introducer may be helpful to track its course along the guidewire. Percutaneous subclavian vein access has been made possible largely by the peel-away introducer technique, which allows access to be achieved through the Seldinger technique and removal of the sheath subsequently from the retained pacemaker lead. A variety of techniques has been reported. The subclavian window approach entails puncturing near the apex of the angle formed by the first rib and clavicle and aiming medially and in the cephalic direction. The medial aspect of this approach has a better success rate and a lower risk of pneumothorax and vascular injury compared with a more lateral entry because the vein is a larger target and the apex of the lung is more laterally situated. The tighter binding between the first rib and clavicle may, however, result in the subclavian crush phenomenon with insulation failure, particularly in the case of bipolar coaxial polyurethane leads. The “safe introducer technique,” as described by Byrd, relates to a safety zone between the first rib and clavicle, extending laterally from the sternum in an arc. More lateral approaches may avoid soft tissue entrapment (subclavius muscle, costocoracoid ligament, and costoclavicular ligament) and may, therefore, extend lead longevity. Cannulation of the extrathoracic portion of the subclavian vein (the axillary vein) has been increasingly used, with puncture made anteriorly to the first rib, maneuvering posteriorly and medially, but remaining lateral to the juncture of the first rib and clavicle; in the more lateral locations, care must be taken to avoid puncturing the subclavian artery. The use of radiography has been advocated during the introduction of needles, whatever may be the technique chosen, to confirm point of entry and subsequent trajectory (Figure 32-5); in some cases, dye injection with venography may facilitate venipuncture (Figure 32-6), particularly in cases where access has been difficult and the risk of subclavian vein thrombosis exists. This may be particularly effective in guiding venipuncture when using the axillary vein approach. Occasionally, Doppler techniques to facilitate vein localization and venipuncture may be used. In patients who have superior vena cava, innominate vein obstruction, or both, stent dilation has been considered to achieve access without going to the contralateral chest. Once access to the subclavian vein has been achieved, an incision must be made to allow for the development of the pocket if the puncture was percutaneous and not from within the wound. The peel-away-introducer technique then allows for passage of the introducer over the guidewire and subsequent passage of the pacemaker lead through the introducer. If the leads are small (especially if unipolar), both may be guided through a single introducer. More commonly, the guidewire is retained after passage of the first lead to allow for the passage of a second introducer and pacemaker lead, which obviates the need for a second venipuncture (Figure 32-7); alternatively, two guidewires may be passed through a single percutaneous introducer with subsequent sliding of the introducer over each guidewire separately to provide independent access for each of two pacing leads. Occasionally, a recently introduced lead may cause problems (e.g., a need to switch from a passive fixation to active fixation lead) with loss of previously established venous access. In such cases, a blade may be used to slit the insulation of the lead to be sacrificed, a guidewire wedged through this insulation, and the lead advanced with a guidewire as a unit so that the guidewire enters the vascular space. With the guidewire held in place, the lead to be sacrificed may be advanced slightly so as to disengage it from the guidewire; in this manner, the guidewire is retained within the vascular space, the old lead may be removed, and a new lead may be placed through a peel-away introducer placed over the guidewire (Figure 32-8). The technique required for lead manipulation may vary as a function of the lead used and the cardiac chamber to be accessed. For right ventricular apex positioning, one approach is to prolapse the lead across the tricuspid valve (Figure 32-9). The other commonly employed approach is to create a curve on the stylet and guide the lead to the right ventricular outflow tract, subsequently withdrawing the lead until it drops into the right ventricular apex position (Figure 32-10); this approach ensures that passage has been achieved into the right side of the heart and reduces the inadvertent placement of the lead into the coronary sinus. With any lead manipulation, great care must be undertaken to avoid dislodgment of other leads already in place, particularly if these have been recently placed. In addition, placement of the leads may result in the induction of ventricular arrhythmias and trauma to the atrioventricular node or right bundle (of great concern in patients with pre-existing left bundle branch block), dictating the need for backup equipment for external pacing and defibrillation. Placement of the ventricular lead in patients with persistent left superior vena cava may be particularly challenging. The loop-de-loop technique is used in which the lead enters the dilated coronary sinus from the left superior vena cava and is banked off the right atrial wall to re-enter the right ventricular apex. An active fixation lead is recommended for stabilization of position in this case (Figure 32-11). Occasionally patients may require placement of the lead in the right ventricular outflow tract; for example, to minimize electrical interaction with a previously implanted right ventricular apex defibrillator lead, an active fixation bipolar lead should be employed (Figure 32-12). The optimal position for right ventricular pacing to promote cardiac hemodynamics (e.g., apical versus outflow tract) is still being debated, but to date, no definitive answer has been found.

Figure 32-3 Insertion of guidewire through cephalic vein; first lead already inserted through venotomy.

Figure 32-4 Insertion of peel-away introducer over guidewire through cephalic vein; first lead already inserted through venotomy.

Figure 32-5 Fluoroscopic visualization of introducer needle for obtaining subclavian vein access.

Figure 32-6 Peripheral dye injection for venography to guide needle for subclavian vein access.

Figure 32-7 Peel-away introducer technique with retained wire for subclavian access.

Figure 32-8 Insertion of guidewire under insulation of lead to be sacrificed, to re-establish venous access.

Figure 32-9 Prolapse of ventricular lead across tricuspid valve.

Figure 32-10 Passage of ventricular lead into right ventricular outflow tract, with plan to pull back and allow lead to “drop” into right ventricular apex (subtraction image).

Figure 32-11 Active fixation ventricular pacing lead inserted via persistent left superior vena cava, through coronary sinus, and via loop-de-loop into the right ventricular apex in patient with Starr-Edwards valve prosthesis.

Figure 32-12 Patient with right-sided pacer and left-sided defibrillator, with active-fixation ICD lead positioned in right ventricular outflow tract to minimize interaction with right ventricular apical pacing lead. ICD, implantable cardioverter defibrillator.

Biventricular pacing has been increasingly used as a method to facilitate cardiac resynchronization therapy, most commonly during defibrillator placement and, to a lesser extent, to alleviate symptoms of heart failure in patients who are not candidates for defibrillator implantation. Placement of a second ventricular lead to enable left ventricular pacing has been accomplished via the coronary sinus approach, though epicardial or trans-septal approaches may on occasion be used. Engaging the coronary sinus can be difficult, especially in patients who have undergone previous cardiac surgery; it is most easily achieved via left-sided implantation. Of the many techniques that have been devised, the most common one is cannulation of the coronary sinus, which may be achieved with a deflectable electrophysiology catheter and confirmed by obtaining left atrial recordings. Thereafter, a sheath may be advanced over the electrophysiology catheter, which is then removed. Balloon-occlusive venography with dye injection may then delineate the coronary sinus anatomy and allow for subsequent placement of a coronary sinus lead into a branch allowing for biventricular pacing. This may require tracking of the lead along a guidewire, a so-called over-the-wire approach. Alternative methods to engage the coronary sinus ostium include searching with a glidewire over which a sheath is subsequently advanced and using special preformed catheters such as Amplatz catheters that allow for subsequent passage of a guidewire once the ostium is localized. On occasion, guidewires or glidewires may be necessary to maintain access within the coronary sinus while a separate sheath-guidewire combination is used to pass the coronary sinus lead. Fixation of coronary sinus leads is predominantly passive, though efforts are currently under way to develop alternative methods of fixation.

Manipulation of the atrial lead primarily entails using a straight stylet initially to pass the lead through the vein into the right atrium and then replacing it with a curved stylet. Great care must be exercised, as with manipulation of any stylet, to avoid getting heme on the stylet lest it occlude the lumen of the lead and thereby prevent the passage of other stylets that might be required. In the case of a preformed (J-shaped) passive-fixation atrial lead, engagement of the atrial appendage is the goal and may be appreciated fluoroscopically by the “dog wag” appearance of the engaged lead as it moves with atrial contraction. For active-fixation leads, it is important to test the screw mechanism before attempting passage. Active-fixation atrial leads are either preformed J-shaped ones or require the implanter to form a J by passage of a J-shaped stylet; in either case, it is useful to watch the screw mechanism extend under a magnified fluoroscopic image and then torque the body of the lead clockwise slightly for further stabilization. Less experienced implanters have the misconception that the use of an active-fixation lead per se ensures active fixation and greater stability. It is critical to test fluoroscopically for stability of the lead fixation with gentle traction, particularly as the J-shaped stylet is being withdrawn from the atrial lead. Ironically, better sensing and pacing thresholds may often be achieved with passive-fixation leads; however, active fixation enables positioning the leads in patients with prior atriotomy or who require positioning of the lead in a less orthodox location within the atrium. As to special positioning of atrial leads, some preliminary work has explored the potential benefit of preventing atrial fibrillation by pacing at the Bachmann’s bundle, by interatrial septum pacing, or by both. Dual-site right atrial pacing and bi-atrial synchronous pacing in some studies have been more effective in the prevention or reduction of atrial fibrillation, compared with single-site right and left atrial pacing. Typically, dual-site right atrial pacing consists of pacing simultaneously from leads positioned in the high right atrium and coronary sinus ostium; the proposed mechanism responsible for antifibrillatory effects is a reduction of activation times in the atrium, especially in areas of conduction delay.

A question that frequently arises is how best to place atrial leads in a patient who is in atrial fibrillation or flutter at the time of implantation. One approach is to acutely cardiovert the patient to sinus mechanism, provided no significant risk of thromboembolic phenomena (as assessed by recency of the arrhythmia, trans-esophageal echocardiography, previous anticoagulation, etc.) exists. Another method is to blindly position the lead and use an active-fixation lead, in particular, to allow for a variety of test positions as assessed by atrial signals and electrocardiographic mapping. Cardioversion could be undertaken thereafter in the latter case, or it may occur spontaneously in the case of the paroxysmal fibrillator.

In some situations, the implanter may opt for a single-lead dual-chamber system, particularly for patients with heart block but with normal sinus node function and without atrial arrhythmias. Current models allow for bipolar atrial sensing with ventricular pacing and sensing (unipolar or bipolar), although leads that also allow for atrial pacing have been studied. The advantage of this approach is that atrioventricular synchrony may be achieved with a single lead. It is important to size a patient with regard to cardiac configuration so as to choose a lead with appropriate spacing between the atrial bi-pole and ventricular electrodes. It is ideal to have the atrial electrodes contacting the atrial wall (as opposed to sitting in the blood pool), also allowing enough slack to accommodate changes in atrial electrode positioning that may arise with respiration or change in body position.

Fluoroscopic confirmation of positioning is important, not only in the anteroposterior views but also in utilizing right and left anterior oblique views to assess patients with anteriorly rotated hearts and either confirm or rule out the placement of a lead within the coronary sinus.

Following placement of the lead(s), use of the pacer system analyzer is crucial in evaluating sensing thresholds, pacing thresholds, and lead impedance and for the possibility of diaphragmatic stimulation at high output—either through atrial leads (phrenic nerve stimulation) or ventricular leads (through a thin-walled right ventricle). For active-fixation leads, whether in the atrium or in the ventricle, demonstration of an initial injury current is particularly useful in confirming fixation.

Perhaps the most important step in pacemaker implantation is lead anchoring. An anchoring sleeve minimizes trauma by being sutured (typically a 0-silk) to the underlying lead insulation, conductor, or both (Figure 32-13). The right balance must be achieved between anchoring the sleeve too securely and anchoring it not securely enough; it is easier to bury the sleeves with a purse-string suture with leads implanted via the cephalic route than via the subclavian route. In addition, repeat fluoroscopy should be undertaken once anchoring has been performed to make sure that lead position, redundancy, or both remain stable at baseline as well as with deep breathing. Enough slack should be provided to accommodate tall individuals, particularly those with large respiratory excursions, to prevent undue tension or retraction of the lead. The leads are then connected to the connector block of the generator; it is critical to ensure that the set screw sites are adequately tightened (including both poles in the case of bipolar leads) by gentle tugging on the lead. Application of sterile adhesive over the set screw site may minimize current drain through this locale.

Figure 32-13 Use of anchoring sleeves for fixation of pacer leads to underlying fascia.

Creation of the generator pocket, either with Metzenbaum scissors or forceps or blunt finger dissection, is followed by placement of the generator inside the pocket. It is useful to irrigate the pocket with antibiotic solution. Hemostatic thrombin-containing preparations, absorbable meshes, or both may sometimes be instilled or left within the pocket. Any redundant or excess lead should be placed under the can so that future generator replacements will not be compromised by inadvertent slicing of the lead(s). In some cases, placement of the generator and lead within a Dacron pouch (“Parsonnet pouch”) (Figure 32-14) may allow for more ideal stabilization and anchoring of the system in the prepectoral fat and thereby minimize generator migration and extrusion, or the so-called twiddler’s syndrome. In some patients, a submammary generator placement may be considered for cosmetic reasons; the lead electrodes may be tunneled from the infraclavicular site of entry to the inframammary incision by using a long needle, a guidewire, and an introducer/dilator technique similar to the retained guidewire technique described earlier (Figure 32-15). After insertion of the generator into the pocket, fluoroscopic confirmation of lead stability is important to rule out lead retraction during this process. Potential complications associated with pacemaker implantation are numerous but fortunately uncommon and have been well described elsewhere. A clear inverse relationship exists between operator experience and complication rate; a direct relationship is associated with the use of subclavian puncture. Preparedness for any eventuality, as discussed previously, remains an important goal. Although problems with bleeding are usually readily apparent, as in complications due to arrhythmia induction, the two most worrisome issues likely to be encountered are sudden hypoxemia and hypotension, which may occur independently or together. The former raises the possibility of pneumothorax, oversedation, or air embolism (when the introducer technique is employed), whereas the latter may include a variety of issues such as ongoing bleeding (suspected or otherwise), hypovolemia, medication, left ventricular dysfunction, pneumothorax, or cardiac tamponade. Some of these complications may lead to a vicious downward spiral; it is, therefore, incumbent on the implanter to keep close scrutiny on the vital signs, oximetry, and rhythm and remain in constant communication with the other team members in the operating arena who are monitoring these factors.

Figure 32-14 Use of Parsonnet pouch.

Figure 32-15 Atrial and ventricular leads inserted via a left subclavian approach, tunneled to a left submammary location for generator placement.

Pacemaker Upgrades, Revisions, and Generator Replacements

On occasion, it may be necessary to upgrade an existing pacemaker system. This is most commonly encountered in patients with single-chamber ventricular systems who experience pacemaker syndrome, which may be overt or subclinical; this would warrant a switch to a dual-chamber system. Increasingly, patients with congestive heart failure are requiring an upgrade to a biventricular system. Considerable operator experience is required for this upgrading procedure; initial reports of these procedures were associated with a remarkably high complication rate, but it is hoped that it has been reduced over time. Obtaining previous operative notes is extremely useful to ascertain which vein was previously used. If the original route was subclavian, was it because there was no identifiable cephalic vein, or was it the implanter’s preference? If the latter, an accessible cephalic vein may well be available to accommodate the new atrial lead, which would require the cutdown technique as previously described. If no cephalic vein is available, the subclavian vein must be used. In case of any doubt as to the viability of the vein vis-à-vis the risk of thrombosis, dye injection of the ipsilateral brachial or axillary vein is helpful. Otherwise, percutaneous subclavian vein entry through the skin or from within the wound is undertaken, with great care to avoid needling or cutting the insulation of the previously implanted lead. Radiographic visualization of the searching needle trajectory is particularly useful in this situation.

If subclavian vein thrombosis is present or the infraclavicular space is too tight to accommodate a second lead (even the smallest unipolar available), then access may be attempted via the contralateral chest with tunneling of the new lead under the skin to the original pacer site (Figure 32-16). The alternative would be to abandon the original site altogether and place a new dual-chamber system via the contralateral chest. If the new lead is to be implanted and tunneled back, a smaller incision can be used; once again, anchoring is of vital importance. For tunneling, a Kelly clamp can be advanced bluntly in the subcutaneous tissue from the receiving (original) site to the satellite (contralateral) site. The free terminal end of the new atrial lead may be placed through a Penrose drain with a gentle tie applied around the drain just distal to the lead connector. The free end of the Penrose drain is then grasped and pulled through the tunnel, back to the original implantation site; the tie is released and the drain is then removed. Alternative approaches include the use of a guidewire and the peel-away introducer technique (introduced from the original site to the satellite location), with passage of the terminal end of the new lead back through the sheath to the original site; a chest tube may also serve as the tunneling conduit. Great care must be taken to strive for a tunnel that is deep (as close as possible to the overlying muscle) and to avoid traumatizing the lead during the tunneling process.

Figure 32-16 Right-sided pacer generator and ventricular lead, with the atrial lead placed via the left side and tunneled over to the contralateral generator site.

Less commonly, the contralateral site may be used for the new lead, as well as for the creation of a new pacemaker pocket with placement of the new generator. Under these circumstances, the original lead is then tunneled under the skin, by using the same procedure described above, to the new (satellite) location. Depending on the available remaining length of the original lead, a lead extender may be required to traverse the distance to the new site.

Not infrequently, existing lead(s) may deteriorate because of insulation breach or conductor fracture. Placement of a new lead is then required, either through the original site or via the contralateral chest. The same techniques apply, as discussed above, with an upgrade from a single-chamber system to a dual-chamber system. The implanter may decide to abandon the original site altogether and place a new system via the contralateral chest, leaving the original system intact, removing only the old generator (with capping and anchoring of the old lead[s]) or removing of all of the previous hardware (generator and leads). Provided no evidence of infection or erosion is present, old leads may be retained, that is, without mandating extraction.

Generator replacement has been an increasingly important procedure, whether to meet elective replacement indicators or because of device advisories; this undoubtedly reflects the enhanced longevity of patients with pacemakers. It is a commonly undertaken procedure but its importance is often minimized; in fact, it requires a lot of advance thinking. This is particularly the case for the patient with pacer dependence. It is important to establish whether any escape rhythm is present by slowly lowering the programmed rate. If no spontaneous rhythm emerges, consideration must be given to how to maintain perfusion when the old generator is disconnected from the chronic leads. Temporary transvenous pacing or noninvasive external (Zoll) pacing are alternative solutions to quickly changing from the old generator to the new generator (provided that the implanter has nimble hands!). For unipolar systems, as soon as the generator is lifted out of the pocket, capture will be lost; to facilitate conversion to a new generator, a “money clip” may be externally attached to the generator with its associated alligator clip connected to the skin retractor at the pocket site. The new generator must be compatible, either primarily or through adapters, with the existing leads; knowledge of the previous system is therefore critical—with regard to lead manufacturer, nature of the terminal pin, and polarity. Visual inspection of the leads and determination of thresholds and impedances—at baseline as well as with gentle traction on the leads—are all important maneuvers that must be undertaken to make sure that lead replacement is not required (in addition to generator replacement). Rarely, repair of a conductor fracture may be undertaken using splicing techniques; occasionally, a terminal pin modification may be made with splicing techniques if an otherwise-needed adapter is unavailable. Not uncommonly, an anchoring sleeve may be applied with sterile silicone adhesive to repair an insulation breach in the lead. One note of caution that applies to generator changeovers is as follows: An alarmingly higher incidence of infections is noted compared with primary implants because insufficient attention is paid to meticulous aseptic technique during these more ambulatory procedures.

Management of Pocket Hematoma, Erosion, Infection, and Pacer Extraction

In the perioperative time frame, it is not uncommon to encounter pacer pocket hematomas, particularly (1) if the procedure has been associated with venous back-bleeding at the lead insertion site, (2) if arterial bleeding has been encountered, or (3) if a tear has been made outside the fascial plane during creation of the pocket; the use of anticoagulation or aspirin and, increasingly, clopidogrel, will also predispose the patient to problems in this regard. Arterial bleeding will result in the rapid formation of a sizable and enlarging hematoma and requires immediate exploration. In the case of less dramatic hematomas, cautious observation is warranted to watch for undue tension on the overlying pocket wall and subsequent tissue necrosis. Needle aspiration of the pocket may result in some decompression but should generally be avoided because it will not remove clots and may, in fact, introduce infection.

Rarely, the decision may be that the generator will be removed and not replaced. For example, certain patients elect to have the device removed because of ongoing implant-related discomfort that does not dissipate with time (so-called pacemakerodynia). It is always wise to review the original indications for pacer implantation while considering the removal of a device without replacement to avoid second-guessing the past decision.

The decision to remove one or more extant leads is the more difficult one than the decision to actually perform the corresponding procedure. Unequivocally, device-associated infection is best treated by removal of all associated hardware. The decision to do less—that is, clean the site and the pacemaker and plan for reimplantation at the same site or a distant site—has been reported but is not recommended. Once the skin barrier has been broken, colonization occurs and infection is likely; if the erosion or infection occurred because of previous indolent infection at the time of implantation or by secondary seeding, then clearly infection was present at the outset.

Extraction of leads may be undertaken transvenously or through a more extensive open-heart surgical approach (i.e., sternotomy or thoracotomy). An intermediate procedure called the trans-atrial approach has been described by Byrd; it is reserved for patients whose leads are not accessible or removable through the inferior vena cava or the superior vena cava. During this procedure the right atrium is exposed when the third or fourth right costal cartilage is removed, the pericardium is opened, and a purse-string suture is placed in the right atrium; a biopsy instrument is then inserted through the purse-string, and the lead is pulled out of the atrium.

Some clinicians have made a clear the distinction between extraction and simple lead removal: In the former, the leads are more difficult to take out of the patient. A policy conference of the Heart Rhythm Society has proposed that “extraction” apply to the removal of any transvenous lead that has been implanted more than 1 year ago or that requires the use of tools beyond standard stylets or simple traction. Indeed, the procedure can be quite challenging and potentially dangerous, even in experienced hands. In one large database, the risk of incomplete or failed extraction increased with implantation duration, less experienced physicians, ventricular leads, noninfected patients, and younger patients. Major complications were reported in 1.4% of patients (<1% at centers with more than 300 cases), and complication risk was associated with increased number of leads removed, female gender, and less experienced physicians. The risk includes death, nonfatal hemopericardium or tamponade, hemothorax, arteriovenous fistula, need for transfusion, pulmonary embolism, and stroke. Unequivocally, a learning curve associated with extraction techniques does exist. The procedure is rarely emergent. As is the case with pacer implantation, the physician embarking on extraction must be prepared in advance to address any emergent complication, with particular emphasis on defibrillation, pericardiocentesis, cardiac surgical backup, or all of these. Large-bore intravenous access and arterial line monitoring are essential. Temporary pacing leads should be inserted in all patients who are pacer dependent.

Three transvenous approaches have been described for lead removal: (1) mechanical, (2) laser, and (3) electrosurgical. Mechanical approaches entail traction on the lead; removal by simple pulling was more easily achieved decades ago with leads that were made of silicone rubber and were nontined or short-tined. During application of the lead, direct traction by pulling on the lead (preferably with a standard lead stylet inserted within) is undertaken, with just enough force to feel the tugging of the heart without inducing chest pain, mechanical embarrassment with hypotension or tamponade, or ventricular arrhythmias. Such force may be applied for minutes, although in the past, various weights or elastic bands were used to allow constant traction for a period of days. Excessive force may result in stretching or tearing of the lead or may induce damage either in the vein or at the tissue-electrode interface.

Improved fixation techniques used to minimize lead dislodgment have ironically led to increased difficulty with lead extraction when required. As a result, countertraction and counterpressure techniques and devices have been developed to facilitate extraction. The use of locking stylets has made it far easier to apply direct traction. The superior lead extraction approach entails opening the pocket and using lead clippers to remove the terminal connector from the pacer lead to be extracted. The insulators and outer conductor coil (in the case of coaxial leads) are trimmed back to expose the inner conductor coil, and the opening of this coil is then broadened with a coil expander. Sizing of the inner conductor coil is then undertaken, typically with a set of variably sized gauge pins, to select the largest locking stylet that will fully enter the inner conductor coil. The locking stylet is then introduced and advanced to the lead tip. In some stylets, counterclockwise rotation may be required (Cook Vascular, Leechburg, PA), whereas in others (Wilkoff stylet, Cook Vascular), removal of a latch pin and pushing of the locking cannula forward are required to activate the locking mechanism. In yet another model (Spectranetics, Colorado Springs, CO), a lead-locking device stylet has a fine, wire mesh stretched over its entire length; the mesh is released once the stylet is advanced and by bunching up holds the lead along its entire length (Figure 32-17). Tugging on the stylet to ensure the adequacy of locking is followed by ligating the end of the lead insulation with 2.0 suture and tying the suture ends to the locking stylet loop handle. This handle is flattened and placed through a preselected sheath set (telescoping inner and outer sheaths).

Figure 32-17 Special mesh locking stylet that expands along the entire length of the lead to be extracted.

Standard sheaths are made of a plastic, such as Teflon (E.I. DuPont, Wilmington, DE) or stainless steel. The latter are used typically during initial entry into the central venous circulation and are used to cut through dense fibrosis near the subclavian site; then they are exchanged with the more flexible plastic sheaths that are used to negotiate through the various curves encountered along the venous path. Continuous and moderate tension is applied on the locking stylet as first the metal set and then the plastic sheaths are advanced to disrupt the fibrotic deposits (the outer sheath has a sharp cutting edge that is advanced over its inner sheath). Fluoroscopic guidance is deemed essential, on the basis of the recognition that misdirected dilators may result in serious vascular injury, particularly at curvatures in the vein where the more flexible plastic sheaths are required (Figure 32-18). If too much tension is applied to the lead–locking stylet combination, the same risks associated with conventional external traction may arise: tearing the lead, avulsing the vein or heart wall, or disengaging the locking stylet from the lead. The larger sheath is advanced over the inner sheath, while the smaller sheath is always kept on the leading edge in a telescoping forward movement. A snow plow effect may arise with scar tissue that is peeled away from the venous wall and pushed in front of the sheaths, thereby preventing further advancement of the dilators. When the sheath set approaches the lead tip near the tissue–electrode interface, the outer sheath is removed and reversed so that its blunt end faces the myocardium and countertraction is then applied against the myocardial surface to release the lead tip. In some cases, after a chronic (noninfected) lead is removed, the retained sheath may be used to place a guidewire and then a peel-away dilating sheath is used to guide the placement of the new pacemaker lead; occasionally, balloon venoplasty may be required as an adjunct.

Figure 32-18 Use of telescoping (inner and outer) extraction sheaths over the lead to be removed.

Powered sheaths have been developed to reduce the need for traction and counterpressure. The laser sheath is used to deliver excimer laser energy fiberoptically to the distal end of the sheath to dissolve the encapsulating fibrotic tissue in circumferential fashion (Figure 32-19). The laser has a very short depth of penetration, affecting only tissue that is in direct contact with the end of the sheath. This releases the lead from its tissue attachments, thus facilitating advancement of the sheath over the lead. An electrosurgical dissection sheath using radiofrequency energy with a more directed sheath tip is currently under active investigation.

Figure 32-19 Cross-section of excimer laser sheath.

Snares may be employed to apply indirect traction in extracting lead(s) by using a femoral approach. The snare device is used to encircle the free tip of the pacing lead or a loop of the lead, with traction then applied from below (Figures 32-20 and 32-21). The approach may be challenging because it is often difficult to ensnare a lead, but it may be less injurious because the coring out of surrounding fibrotic tissue is not required in this approach; nonetheless, the operator must be aware of the associated risks, femoral vein injury and thromboembolism, as well as the same potential complications associated with traction of the lead from above. The technique is indicated (1) if the lead to be extracted is not accessible from the venous entry site, (2) if the lead has been cut or fractured, or (3) if there has been retraction of the lead into the central venous circulation, intracardiac space, or both. The author’s group found the technique to be particularly well suited to removing atrial leads under the Accufix advisory associated with fracture of the inner retention J-shaped wire, particularly if this wire is protruding. If the lead is still anchored in the pectoral region, it must first be freed. Thereafter, a sheath with a hemostatic valve is placed via the femoral vein to the inferior vena cava level just below the atrium, and through this the grasping tool is deployed. Tools available for this include a deflecting tip guidewire and Dotter helical basket retriever, pigtail catheter, or Amplatz catheter; special countertraction sheaths are also available.

Figure 32-20 Fluoroscopy of the right ventricular apical lead being extracted from a femoral approach/snare technique in a patient with a dual-chamber pacing system and separate defibrillator lead in the right ventricular outflow tract.

Figure 32-21 Right ventricular pacing lead after removal via the snare technique (same patient as Figure 34-20).

It is clear that lead extraction is a procedure that is not undertaken lightly, may be hazardous, and requires specialized training and careful deliberation and preparation. Indeed, in some series (e.g., Accufix leads), the risk of extraction over time has exceeded that associated with retention of the lead. In some cases (e.g., infected pacer systems), extraction is essentially unavoidable, but precedents for abandonment without extraction of noninfected leads do exist.

Conclusion

Implantation and revision techniques have remained relatively constant over time. What remains paramount is an appreciation of the goals of implantation; thoughtful preparedness with regard to materials and approaches that will be required; anticipation of potential problems that will need to be addressed; and, perhaps most important, an experienced implanter who can respond appropriately when difficulties are encountered. Above all, complacency should be avoided because unfamiliar and unexpected circumstances do tend to arise.

Acknowledgment

The author thanks Mike Dabbraccio, David Kalinchak, and Ronald Quain for their excellent technical and photographic assistance.