Intravascular Lead Research Articles

Endocardial Pacemakers in Children: Lead Length and Allowance for Growth

Permanent endocardial pacing in small children is feasible but is limited by two problems: sufficient extra lead has to be left within the heart to allow for growth and the excess has to be coiled behind the pacemaker, limiting the benefit from smaller generators. The required intravascular lead length in 120 children and adults was measured on posteroanterior chest X ray and was correlated with standing height. Measurements were made from the mid-point of the left clavicle to the apex of the right ventricle in a curve simulating the usual endocardial lead position. In 60 children, aged 2.0-15.9 years, intravascular lead length (range 15.5-29.0 cm) correlated well with height (0.83-1.70 m), r = 0.91. In 60 adults, mean age 54.9 years, intravascular lead length (25.5-35.6 cm) also correlated well with height (1.45-1.85 m), r = 0.71. In 20 adults the excess extravascular lead length, measured during pacemaker implantation via the subclavian route, was 15.1-33.7 cm and was inversely correlated with height. A child's eventual adult height can be predicted and, using our data, the extra length of lead necessary to allow for growth can be computed. Available endocardial pacing leads are usually 58- to 64-cm long. The excess extravascular lead is a major practical difficulty in children. Shorter leads would avoid the problem of excess lead and facilitate long-term pacing in small children.

Initial experience with transvenous implantable cardioverter defibrillator lead systems: operative morbidity and mortality.

Introduction of non-thoracotomy lead systems (Medtronic, Inc.) for the implantable cardioverter defibrillator (ICD) has expanded the indications for use of this mode of therapy. Patients previously considered "too ill" to undergo a thoracotomy as well as patients who are at a high risk for developing sudden death but without previous cardiac arrest, are now considered candidates. The initial experience with the non-thoracotomy lead system at our institution was analyzed for morbidity and mortality. Thirty-four patients underwent attempted intravascular lead implantation, with 30 having initial successful implantation (88.2%). There were 23 males; average ejection fraction (EF) was 38.6%. Three patients developed pulmonary edema and low output immediately after the procedure. Three patients developed electromechanical dissociation during defibrillation threshold testing. A prolonged testing time for the non-thoracotomy lead system was noted when compared to the thoracotomy system (57.39 vs 32.30 min; P < 0.0000). There were more intraoperative morbidities with the non-thoracotomy leads than with the thoracotomy system. There were no perioperative deaths. The potential consequences of prolonged anesthesia time and extensive defibrillation threshold testing should be considered when choosing the route of ICD implant, the type of anesthesia, and the intraoperative testing protocol for each patient.

Intravascular Lead Extraction Using Locking Stylets, Sheaths, and Other Techniques

Septicemia necessitates extraction of chronic pacemaker leads. Using locking stylets and sheaths to extract leads via the implantation vein (subclavian, cephalic, or jugular) and maneuvering devices, sheaths, and retrieval baskets via the femoral approach, extraction of 228 leads implanted 5 days to 240 months (mean 55 months) was attempted in 136 patients (mean 62 years) at 34 institutions. In addition to septicemia (9%) and infection (39%), total 48%, indications included prophylaxis/replacement (40%), and other (12%). Seventy-seven leads were atrial, 151 ventricular; 147 were unipolar, 81 bipolar; 96 had silicone insulation, 127 polyurethane, 1 poly/silicone, and 2 undetermined. Fixation included tines or fins (160), screw (40), flange (12), and other (16). One hundred and ninety-four leads were completely extracted, 19 partly extracted, and 15 not extracted. Procedural complications were: torn atrium requiring open heart repair (1), hemothorax requiring a chest tube and blood transfusions (1), subacute hemothorax requiring drainage 18 days after discharge (1), thrombosis treated by drugs (1), and myocardial avulsion without sequela (1). Important observations included the significant training required due to the large number of possible clinical variables, and the need to be prepared for life-threatening cardiovascular complications. With training, procedures done at higher volume and lower volume institutions met with similar success. Intravascular lead extraction is a viable technique whose benefits outweigh the risks, given the proper intensive training and open heart surgical backup, and may obviate the need for open heart surgery for lead extraction.

Intravascular Lead Extraction Using Locking Stylets and Sheaths

Chronic lead extraction using intravascular countertraction techniques was studied in patients with over 65 different lead models including passive and active fixation devices. Indications for removal of 115 leads implanted 5 days to 264 months (mean 58 months) in 62 patients (mean 65 years) included septicemia, subcutaneous tissue infection, preerosion, free-floating lead, lead trapped in valve, too many leads, pain, and vein thrombosis. The superior vena cava (SVC) approach was attempted in 101 leads and was successful in 82 attempts (71% of total leads). The inferior vena cava (IVC) approach via the femoral vein was required to extract 14 (12%) leads inaccessible to the SVC approach and the 19 leads that failed the SVC approach (29% of total leads). The SVC procedure includes a sized stylet locked at the tip and telescoping sheaths advanced over the lead to the heart. An IVC procedure includes placement of a 16 F sheath workstation via a femoral vein into the right atrium. A deflection catheter and Dotter snare in an 11 F sheath were advanced through the workstation into the right atrium. The lead was maneuvered into position, snared, and pulled into the workstation. For both the SVC and IVC approaches, the leads were removed by applying traction on the lead and countertraction with the sheaths. In experienced hands, these techniques have proven safe and effective for removing chronic transvenous leads.