Heidi J. Smith

Five-Years Experience with Intravascular Lead Extraction

From December 1988 to April 1994, the extraction of 2,195 intravascular pacing leads from 1.299 patients was attempted at 193 centers. Indications were: infection (54%, including 10% septicemia), pacemaker reoperation with removal of nonfunctional or incompatible leads (40%), and other causes (6%). Extraction was attempted via the implant vein using locking stylets and dilator sheaths, via the femoral vein using snares, retrieval baskets, and sheaths, or via both approaches. Leads had been implanted for 0.2 months to 24 years (mean 56 months). At the conclusion of the intravascular procedure, 86.8% of the leads were completely removed, 7.5% were partially removed, and 5.7% were not removed. For physicians performing their first case, 12% of leads were not removed; for physicians who had performed more than 10 cases, only 2% of leads were not removed. Of the 189 leads where extraction attempts had previously failed, 75.1% were completely removed, 14.8% were partially removed, and 10.1% were not removed. Scar tissue increased in severity with implant duration, was a complicating factor, and was the main cause of failure to remove leads. Use of the femoral approach increased with implant duration (5% of leads implanted 12 months or less, 11% of leads 13 months to 3 years, 20% of leads 4–7 years, and 31 % of leads 8–24 years), primarily because of increasingly abundant scarring and prior lead damage. Fatal and near fatal complications occurred in 2.5%. including 8 (0.6%) deaths (3 hemopericardium/tamponade, 1 hemothorax, 3 pulmonary embolus, 1 stroke). With experienced operators, appropriate precautions, and appropriate patient selection, modern techniques allow the successful extraction of up to nearly 98% of intravascular leads with a relatively low incidence of complications.

The Exercise-Responsive Cardiac Pacemaker

The heart has two properties: rhythmicity and contractility. Rhythmic contractions are initiated by the hearts pacemaker, the sinoatrial node, which lies in the right atrium. If the sino-atrial node fails, or if its electrical excitations are not propagated to the ventricles (the main pumping chambers), they wil still contract rhythmically but at a rate that is sometimes too slow to provide enough cardiac output to sustain consciousness. It is for this reason that rhythmic electrical stimuli are delivered to the ventricles in order to increase cardiac output to a level adequate to permit the subject to perform routine daily tasks. The technique of applying rhythmic electrical stimuli to the ventricles is called cardiac pacemaking; it can be achieved in several interesting ways, as this paper will describe.

Intravascular Lead Extraction Using Locking Stylets and Sheaths

BYRD, C.L., ET AL.: 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.

Intravascular lead extraction using locking stylets, sheaths, and other techniques.

FEARNOT, N.E., ET AL.: 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 (39Y0), 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 (1601, screw (401, 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. Conclusion: 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 Extraction of Chronic Pacemaker Leads: Efficacy and Follow-Up

Extraction of chronic pacemaker leads has been recommended for infections, prevention of venous thrombosis, migration, and possible perforation. Success with constant traction techniques has been variable, and the cost and morbidity of open chest surgical procedures are prohibitive. Efficacy of a new system for lead extraction using intravascular techniques was analyzed. The system (Cook Pacemaker) uses a locking stylet, which is secured at the distal electrode by counterclockwise rotation to reinforce the lead and facilitate traction, and dilator sheaths that are used to free the lead from adhesions in the venous system. In a series of 56 patients (ages 19–88)who presented for lead extraction because of erosion (5), infection (14), lead replacement (35), or other (2), 86 leads were extracted. Thirty‐two were atrial leads and 54 ventricular; 23 had active fixation and 63 passive. Average duration of implant was 58 ±42 months (range 1–264). Eighty‐four leads were totally removed and two partially removed. For these two leads, the distal tip was not removed; in both cases the locking stylet was not secured at the distal electrode due to obstruction within the lead. Two patients developed arm edema following the procedure, which resolved with elevation. One patient developed a subclavian thrombosis, which resolved with warfarin anticoagulation. Four patients have expired due to unrelated causes. In conclusion, this intravascular approach for extraction of chronic leads is effective, and the procedure is safe when performed by experienced personnel.

Evaluation of the Temperature Response to Exercise Testing in Patients with Single Chamher, Rate Adaptive Pacemakers: A Multicenter Study

FEARNOT, N.E., et al.: Evaluation of the Temperature Response to Exercise Testing in Patients with Single Chamber, Rate Adaptive Pacemakers: A Multicenter Study Temperature responsive pacemakers were implanted in 45 patients (ages 44 to 90); 31 patients were evaluated by randomized, paired treadmill exercise tests 1 month postimplant. Of 28 males and 17 females, 19 had coronary artery disease; 8 had congestive heart failure. Pacing indications included sinus node disease (26), atrial fibrillation (15), AV block (10), and brady/tachy syndrome (10); some had multiple indications. Blood temperature (every 10 seconds, resolution = 0.004°C) and pacing rate (every minute) were telemetered from the pacemaker. Average heart rate, exercise duration (5.7 min VVI; 6.7 min VVIR), WIR response time (22 sec), initial temperature drop (0.23°C) and maximum rate of drop (0.65°C/min), temperature rise (0.31°C VVI; 0.38°C VVIR) and rate of rise (0.27°C/min) were studied in a subset of patients. In pacer‐dependent patients, average paired increases in exercise duration and heart rate were 56% and 34%, respectively. Including all (31) patients, some with intermittent sinus rhythm, increases were 28% and 9%, respectively. Because exercise duration increased, temperature rise was higher with rate adaptation. Rate adaptation was obtainable in all patients and patients averaged 99 ± 48 increases above basic pacing rate per day at nominal temperature sensitivity. Conclusion: Beneficial rate adaptation is achievable using blood temperature to modify rate in a sensor based system.

Trends in Pacemakers Which Physiologically Increase Rate: DDD and Rate Responsive

Exercise (rate) responsive pacemakers benefit patients by providing increased cardiac output when needed and permitting lower rate during rest. This paper briefly reviews trends in reported studies on rate responsive pacemakers. For patients with reliable atrial rhythms, atrial‐triggered pacemakers (DDD) provide physiological ventricular rates unless complications arise. At low rates, A‐V synchrony benefits patients with refractory cardiac decompensation; however, in patients with healthy myocardiums, achieving higher pacing rates is more significant than maintaining synchrony. If atrial rhythms are unreliable, an alternative sensor for determining pacing rate is indicated. Pacemakers that respond to changes in right ventricular blood temperature, respiratory rate, QT interval, body vibration (motion), and pH have been implanted in humans. Clinical evaluations have shown that increased pacing rate leads to increased exercise tolerance and cardiac output when needed, independent of the sensor type (DDD, QT, respiratory rate, etc.). The effectiveness of any sensor type to increase pacing rate appropriately requires reliable sensors that respond specifically to the need for increased pacing rate. Sensors for stroke volume, venous oxygen saturation, right atrial or ventricular pressure and catecholamines are also under preclinical investigation. The availability of a reliable, long‐term sensor is a key limitation to several techniques including pH. stroke volume, oxygen saturation, pressure, and catecholamines. Sensor technology and clinical effectiveness are the keys to rate responsive pacing.

Right ventricular blood temperature profiles for rate responsive pacing.

To establish the efficacy of a temperature‐based pacemaker control algorithm, right ventricular temperature and heart rate were measured for 12–70 hours in eight patients (51 ± 17 years) and in one normal volunteer (28 years) during a variety of activities including exercise, rest, sleeping, eating, drinking, and bathing. A diurnal variation in heart rate and temperature was observed. Drinking caused transient temperature changes (less than one minute); during eating, increases of 0.07–0.36°C over 3–12 minutes were observed. An increase of 0.24°C over 8.5 minutes was observed in one patient during bathing. An abrupt drop in temperature was typically observed at the onset of exercise, followed by a steady temperature rise. During treadmill exercise, after a drop (0.13–0.48°C, Bruce n ‐ 4; 0A6–0.34°C, Naughton, n = 3) during the first 1–2 minutes, temperature rose steadily through the end of peak exercise (0.45–1.01°C, Bruce; 0.28–0.47°C, Naughton). A temperature dip was also observed when a patient was told exercise would start but the treadmill failed to turn on. The dip is probably secondary to changes in blood flow from the peripheral circulation to the central system at the onset of exercise. Repeated exercise separated by short rests caused progressive blunting of the initial dip. Right ventricular temperature changes in a predictable manner with daily activity, allowing a temperature algorithm to detect rest and exercise.

Electrosurgical safety of guide wires during endoscopic sphincterotomy

UNLABELLED A study was performed to determine whether alternate site electrosurgical burns could be caused by an inadequately insulated guide wire left in place during endoscopic papillotomy to maintain cannulation of the common bile duct. The safety of four covered guide wires and one standard guide wire was evaluated for electrosurgical safety. All four covered guide wires were coated with polyurethane or polytetrafluoroethylene (Teflon), providing insulation. Leakage currents under normal, limiting case, and fault (damaged insulation) conditions were compared to safety limits. All covered guide wires met safety limits under normal conditions, one of four covered guide wires met safety limits under limiting case conditions, and none met safety limits under fault conditions. The uncovered guide wire did not meet the safety limit under any conditions. CONCLUSION Without a well-insulated guide wire with intact coating, our measurements indicate that leaving a guide wire in place during papillotomy may result in an electrosurgical burn.

Concepts of rate responsive pacing

Various concepts for measuring (by means of biosensors incorporated into pacemakers) biologic parameters to determine the appropriate pacing rate are reviewed. They are pH, stimulus-to-T-wave interval, blood temperature, intercardiac blood pressure change, venous oxygen saturation, intercardiac impedance (stroke volume, ejection rate, preejection interval), thoracic impedance (respiratory rate, minute volume), R-wave area, and body vibration. Those which have been incorporated in an implantable pacemaker and studied in a significant number of patients include intracardiac blood temperature, respiratory rate, respiratory minute volume, stimulus-to-T-wave interval, and body vibration. Studies of intracardiac impedance, QRS complex area, venous oxygen saturation, and right ventricular pressure are in early stages. Because no single parameter has yet proved to be an ideal indicator of metabolic need, dual-chamber pacemakers, which use atrial rate and body vibration to control pacing rate, and multisensor pacemakers are under development.<<ETX>>