The severity and extent of adhesions can also be exacerbated by the unique construction of the endovascular leads. Most of the major lead manufacturers have experienced lead complications. The two notable examples are the Riata AICD lead(St. Jude Medical, St. Paul, MN) and the Starfix Coronary Sinus lead(Medtronic, Minneapolis, MN). The mode of failure of the Riata AICD lead (St. Jude Medical, St. Paul, MN) is related to insulation failure, allowing the shocking conductors to delaminate of its insulation and extrude from the lead body. The resultant increase in surface area presents to the endovasculature, stimulating scar over a much larger and longer surface area. The cross-sectional profile of the lead for extraction has changed and requires specific techniques to address this complication. Figure 13.2 is a cross-sectional view of the Riata dual coil lead(St. Jude Medical, St. Paul, MN). Note the position of the conductor cables and silicone insulation prior to delamination in vivo. The Starfix Coronary Sinus lead (Medtronic, Minneapolis, MN) also has a unique scar pattern within the coronary sinus and has specific requirements and challenges for extraction.
Fig. 13.2
13.1 Anatomy
The key to lead extraction requires a thorough review of the individual’s extant venous anatomy; the course of the endovascular leads; and the technique of implantation, which is usually performed via the left or right brachiocephalic vein into the cardiac chambers. The pulse generator is generally implanted in the ipsilateral deltopectoral groove. The major brachiocephalic veins on either side are used for central venous access for device implantation. These veins can be accessed by subclavian or axillary puncture with dilation or by cephalic vein cannulation. The lead from the patient’s left side then traverses the left brachiocephalic vein to the lateral side of the superior caval vein. Figure 13.3 demonstrates the usual arrangement from the left subclavian or left cephalic vein approach. Note the laterality of the implant site, to minimize clavicular deformation of the lead. From here, the lead is guided across the right atrium to the ventricle through the right atrioventricular valve. If there is redundancy in the lead, then wherever the lead is in contact with the endocardium can represent an adhesive point. In most cases, the leads that are implanted from the patient’s left side come into contact with the right side of the superior caval vein, as noted in the drawing. Figure 13.4 is a chest roentgenogram demonstrating the course of the endovascular leads, highlighting the curve of the lead as it comes into contact with the superior caval vein at the lateral side. Figure 13.5 shows the usual arrangement of leads that are placed from the patient’s right side. In general, leads placed from the right brachiocephalic veins make contact with the medial superior caval vein, as noted in the drawing. Figure 13.6 is a chest roentgenogram of a typical right-sided dual chamber pacemaker implanted with a right atrial lead and a right ventricular lead. Note the position of the right ventricular lead as it traverses the innominate caval junction on the medial side of the superior caval vein (SCV).
Fig. 13.3
Fig. 13.4
Fig. 13.5
Fig. 13.6
The SCV anatomy has important differences regarding right-sided versus left-sided devices. The lateral portion of the SCV is in contact with the pleura and has additional pleural investments on its wall. The medial portion of the SCV is intrapericardial. This is important because a right-sided lead will typically contact the medial surface of the SCV, whereas the left-sided lead will contact the lateral surface of the SCV. This difference becomes a central issue for preoperative planning and for treatment of potential injuries to the SCV. For example, injuries to the medial SCV from a right-sided lead are typically intrapericardial and are detected by imaging methods such as transesophageal echocardiography and intravascular ultrasound. Left-sided injuries also can be intrapericardial but frequently are intrapleural in nature and are detected with fluoroscopy of the right thoracic cavity.
13.2 What Is Lead Extraction?
It is important to distinguish between lead removal and lead extraction. Lead removal can be accomplished with only the instruments provided in the implant package, with gentle traction on the lead. This usually occurs within the first year after implantation. On the other hand, lead extraction is characterized by the use of additional technologies to lyse intravascular adhesions to facilitate the extractive procedure. This can be accomplished by gentle traction with a locking stylet, mechanical methods using cutting technology, or laser energy techniques.
13.3 Safety Measures and Operative Preparation
Patients are identified based on complications of leads regarding infection, lead malfunction, and venous occlusion. Regardless of the presenting indications, all patients undergoing lead extraction are prepared in a similar manner. Important preoperative considerations in every patient include the presence of pacemaker dependence, anticoagulation status, antibiotic therapeutic protocols, timely blood transfusion availability, cardiopulmonary bypass standby, general endotracheal anesthesia with supine position, defibrillation pads, transesophageal echocardiography, arterial line monitoring, large-bore infradiaphragmatic intravenous access, fluoroscopy, and technology support personnel. Figure 13.7 is a photograph that shows the operating room organizational structure. Hemodynamic, echocardiographic, and fluoroscopic displays should be colocated with easy visualization to facilitate rapid assessment of potential complications and corresponding decision-making. Once these conditions are met, the operation can be commenced with the certainty that all potential complications can be diagnosed and resolved effectively.
Fig. 13.7
Infradiaphragmatic intravenous access can prove to be life-saving if the SCV is injured, because blood resuscitation through brachiocephalic access will be ineffective owing to extravasation through the injury.
Although temporary femoral transvenous pacing can be used for short intervals in patients who are pacemaker-dependent, an exteriorized transjugular standard endocardial pacing lead with an external power source is superior, as it enhances patient mobility during the time of inpatient infection resolution.
13.4 Principles of Lead Extraction
13.4.1 Pocket Management
In the presence of proven infection of the implant pocketor lead endocarditis, the only rational treatment is removal of all hardware and proper management of the infected pocket. In those patients with pacemaker dependence, temporary peripheral leads away from the infected pocket will be necessary to maintain cardiac rhythm.
The pocket is opened along the last previous incision and the wound is cultured. The leads are then identified and isolated with sharp or electrocautery dissection at low levels (electro-cautery set at 20 W) to ensure that no damage occurs to the insulation material surrounding the leads. The sleeve around the lead is controlled at the venous entry site. Sometimes multiple leads and their respective sleeves have been surgically connected by suture techniques. These associated surrounding adhesions must be sharply divided. There are many dissecting methods to isolate the leads. One method is to use a Kelly clamp to spread the surrounding tissue in all four quadrants, with general back traction on the lead in question. Figure 13.8 demonstrates the hemostat spread technique. Once the leads are separated and the sleeves controlled, the dissection can be continued with comprehensive capsulectomy and scar removal (at least 3 mm per side). If there is necrotic skin from erosion of the pocket, aggressive resection of all devascularized tissue and foreign bodies are warranted.
Fig. 13.8
Figure 13.9 demonstrates several key points. First, in the center is the larger area of the wound that is devoid of tissue, representing necrosis and erosion of the pocket. Adjacent to this is the tail of the lead from the previous incision site. Control of the lead is achieved close to the clavicle by means of a counter-incision at the clavicular level; this becomes important to achieve coaxiality of the laser later in the extractive process.
Fig. 13.9
Conscientious hemostasis will prevent further wound complications and should be the norm. At the end of the procedure, after the leads are successfully explanted, pulsed antibiotic irrigation is employed to agitate the wound, remove unwanted necrotic tissue, and provide topical bactericidal potential to the healing process. The wound is then primarily closed over a suction tube apparatus, which is left in place for 2 weeks to enhance tissue coaptation and healing. Eighty-five percent of such closed pockets will have no residual infection and will require no further local therapy, but 6 months should elapse prior to placing any other devices in this area.
13.4.2 Lead Preparation
As noted earlier, lead extraction is highly dependent on the dwell time and endovascular adhesions. Nevertheless, with the proper use of gentle traction with a locking stylet and mechanical methods using cutting or laser technology, over 95% of endovascular leads can be removed from the implant site.
The cornerstone of lead extraction is lead preparation, in which control of the lead tip with a locking stylet is accomplished. In the United States, lead preparation technologies include the LLD stylet (Spectranetics, Inc., Colorado Springs, CO) or the Liberator stylet (Cook Medical, Inc., Bloomington, IN). Both catheters operate on the similar principal of placing a stylet through the length of the lead, then expanding its footprint throughout the lead, thus locking the stylet into place. Figure 13.10 demonstrates the locking stylet types. The principal difference is the place where the locking of the stylet takes place. The LLD stylet (Spectranetics, Inc., Colorado Springs, CO) locks the entire length of the lead, whereas the Liberator (Cook Medical, Inc., Bloomington, IN) locks the lead at the end. Functionally, there is little difference in performance between them.
Fig. 13.10
Lead preparation for the locking stylet is facilitated by amputating the proximal portion of the lead in question while preserving a maximum amount as it exits the insertion site. This allows safe lead manipulation, as shown in Fig. 13.11. The outer lead insulation is stripped of its outer core using a rolling motion against a #15 blade, as noted in Fig. 13.12. The inner core of the lead is then cannulated with the sounding stylet provided, as shown in Fig. 13.13. The sounding stylet is advanced into the entire length of the lead, removed, and measured against the locking stylet. The locking stylet is then inserted into the lead and advanced to the tip, keeping in mind that the stylet may advance further than the sounding stylet measurement. If the lock is bent to a severe angle, it should be removed and replaced, as a bent stylet will not lock past the point of the bend. Once the stylet is in the desired position, it is then locked by advancing the cylinder piece all the way toward the distal lead. This maneuver will expand the footprint, and the lead is now locked in place. Under fluoroscopy guidance, back pressure (tug) is applied to the lead to determine if it will come loose. If it does not loosen, preparation should be made for the use of additional sources of energy. The locking stylet is now ready for binding to the lead body so that constant tension on the lead is maintained throughout its length. This can be accomplished by one of two methods. The first is the One-Tie system (Cook Medical, Bloomington, IN) in which the wire tie is applied to the locked stylet and the lead body. The second technique is the suture tie and loop method, which uses suture loops and ties to bind the lockingstylet to the lead body.
Only gold members can continue reading. Log In or Register to continue
