Laser-assisted lead extraction: the European experience.

AIMS: The aim of this study is to investigate the safety and effectiveness of Excimer laser-assisted lead extraction in Europe. The final European multi-centre study experience is presented. METHOD AND RESULTS: The Excimer is a cool cutting laser (50 degrees C) with a wavelength of 308 nm. The energy is emitted from the tip of a flexible sheath and is absorbed by proteins and lipids, 64% of the energy is absorbed at a tissue depth of 0.06 mm. The sheath is positioned over the lead, and the fibrosis surrounding the lead is vaporized while advancing the sheath without damaging other leads. From August 1996 to March 2001, 383 leads (170 atrial, 213 ventricular) in 292 patients (mean age 61.6 years, range 13-96) were extracted at 14 European centres. Mean implantation time was 74 months (3-358). Most frequent indications were pocket infection (26%), non-functional leads (21%), patient morbidity (21%), septicaemia or endocarditis (14%), erosion (5%), and lead interference (8%). Median extraction time was 15 min (1-300). Complete extraction was achieved in 90.9% of the leads and partial extraction in 3.4%. Extraction failed in 5.7% of the leads. Major complications = perforations caused 10/22 (3.4/5.7%) of the failures. Most partially extracted patients were considered clinically successful, as only minor lead parts without clinical significance were left. Femoral non-laser technique was used to remove 8/12 of the non-complication failures. The total complication rate, including five minor complications (1.7%), was 5.1%. No in-hospital mortality occurred. CONCLUSION: Pacing and implantable cardioverter-defibrillator leads can safely, effectively, and predictably be extracted. Open-heart extractions can be limited to special cases. The results indicate that the traditional policy of abandoning redundant leads, instead of removing them, may be obsolete in many patients.

Reduction of the pace polarization artefact for capture detection applications by a tri-phasic stimulation pulse.

This study investigated the ability to minimize pace polarization artefacts (PPA) by adjusting the post-stimulus pulse duration of a tri-phasic stimulation pulse. Adjustment of the stimulation pulse was enabled by downloading special study software into an already implanted pacemaker. Tests were performed in a total of 296 atrial leads and 311 ventricular leads. Both chronic and acute leads were included in the study. Statistically significant differences were found in the initial PPA (without any adjustment of the stimulus pulse) between atrial and ventricular leads. In addition, significant differences were observed among various lead models with respect to changes over time in the initial ventricular PPA. Successful PPA reduction was defined as a reduction of the PPA below 0.5 mV for atrial leads and below 1 mV for ventricular leads. Results show a success rate for ventricular and atrial PPA reduction of 97.8% and 98.7%, respectively. Threshold tests showed that after reduction of the PPA loss of ventricular capture can be reliably detected. However, atrial threshold tests showed many false positive evoked response detections. In addition, unexpectedly high evoked response amplitudes were observed in the atrium after reduction of the PPA. Results from additional measurements suggest that these high atrial evoked response amplitudes come from the influence of the input filter of the pacemaker.

Bidirectional defibrillation using implantable defibrillators: a prospective randomized comparison between pectoral and abdominal active generators.

The objective of this study was to compare the effects of active abdominal and pectoral generator positions on DFTs in a bidirectional tripolar ICD system. Twenty-five consecutive patients had ICD systems implanted under general anesthesia. A transvenous single lead bipolar defibrillation system and an active 57-cc test emulator in the abdominal and pectoral positions were used in the same patient. A randomized, alternating step-down protocol was used starting at 15 J with 3-J decrements until failure. The mean implantation time was 114 +/- 23 minutes, the mean arrhythmia duration was 14.5 +/- 1.5 seconds, and the mean recovery time was 5.4 +/- 1.1 minutes. The mean DFTs in the abdominal and pectoral positions were 10.9 +/- 5.1 and 9.7 +/- 5.2 J, respectively (NS), the mean intraindividual DFT difference (abdominal minus pectoral) was -0.89 +/- 4.15 J (range -9.5 to 8 J). The 95% confidence interval showed a -2.60 to +0.82 J mean difference (NS). The DFT was < 15 J in 72% and 88% of the patients and the defibrillation impedance was 41 +/- 3 and 44 +/- 3 omega, abdominal versus pectoral positions. There was no difference in DFT between active abdominal and pectoral generator bidirectional tripolar defibrillation. The pectoral position may be considered the primary option, but in cases of high DFTs the abdominal site should be considered an alternative to adding a subcutaneous patch. In some patients, the anatomy may favor an abdominal position. Possible differences in the long-term functionality on the leads are not yet well known and need to be further evaluated.

Cardiac lead extraction with a novel locking stylet.

Extraction of chronically implanted pacing and defibrillator leads is facilitated by using specialized locking stylets placed in the lead to allow application of traction and to stabilize the lead during sheath dissection of fibrotic tissue. We report the initial multicenter series of cases using a novel lead locking device (LLD). In 57 consecutive patients presenting at 6 institutions for lead extraction, 99 leads were treated using the LLD. After removing the pulse generator, leads were severed, the inner coil dilated and an LLD was successfully inserted and locked in the inner lumen of 95/99 (96 %) leads. With traction applied to the LLD, a variety of sheaths were advanced over the lead body to separate it from adhesions. In 97/99 (98 %) leads, all or most of the lead was removed via the implant vein; 2 leads were removed via the femoral vein. No major complications were observed. The LLD deploys safely and reliably, and provides stable support for advancement of dissecting sheaths.

Excimer laser assisted extraction of permanent pacemaker and ICD leads: present experiences of a European multi-centre study.

OBJECTIVE: Excimer Laser technique can be used to extract leads. We present the European multi-centre experience. METHOD: The Spectranetics Excimer Laser is a Xenon-Chloride laser with a wavelength of 308 nm, not visible to the human eye. This cool cutting laser (50 degrees C) has an absorption depth of 0.06 mm. The laser energy is emitted from the tip of flexible 12, 14 or 16 French (Fr) probes and is absorbed by proteins and lipids. The fibrotic sheaths usually surrounding leads can be cut without damaging the endothelial wall or the insulation of other leads. RESULTS: From August 1996 to August 1998, 179 leads (104 atrial, 57 ventricular, one SVC, 17 ICD) in 149 patients (mean age 68.3 years, range 14-94) were extracted in 11 centres. Mean implantation time was 68.3 months (2.8-357.8). Most common indications were patient morbidity, non-function, pocket infection, septicaemia or endocarditis. Median extraction time was 10 min (1-189). Most procedures (78%) were performed in operating rooms. Complete extraction was achieved in 89.5% of the leads, 6% were partially extracted and 4.5% of the extractions failed. In the majority of the partial cases, only minor lead parts without clinical significance were left. Of the failures, 3/8 were completely removed by femoral non-laser approach, 1/8 with a right subclavian approach and 1/8 with thoracotomy. Complications were few but included one ventricular perforation that did not need surgery; two other perforations were related to the reimplantation of leads and required surgery. Mean hospital stay was 3 days and all patients were discharged well and alive. CONCLUSIONS: Excimer Laser assisted lead extraction is a safe and efficacious procedure. Open-chest extractions are still necessary but can be limited to very selected cases. These initial results may widen indications from mandatory to include the extraction of many non-functional leads, previously abandoned.

Extracellular amino acids as markers of myocardial ischemia during cardioplegic heart arrest.

Extracellular levels of amino acids in the myocardial interstitium are sensitive indicators of myocyte function. Lowered ATP leads to a rapid extracellular appearance of amino acids with a high intra- to extracellular concentration ratio, such as taurine and glutamate. Nitrogen fluxes are reflected by glutamine, while alanine, glycine, serine and leucine are markers of proteolysis. In addition, degradation of membrane phospholipids is reflected by other primary amines, such as phosphoethanolamine. The time course of these changes was determined before, during and after cardioplegic heart arrest. Two regions of the heart were monitored in 20 patients by means of microdialysis sampling. After only 20 min of heart arrest, extracellular taurine, glutamate and phosphoethanolamine increased transiently up to 25 times the basal level. Ten-20 min later, glutamine increased by 6 times. A doubling of alanine, glycine, serine and leucine levels took place 30 min after release of the aortic cross-clamp. After 2 h, all were at levels similar to those recorded 15-30 h later. Levels of taurine and glutamate in the anterior wall of the heart correlated significantly with those of its lateral wall. The response to surgery and heart arrest was studied in a group of patients with ischemic heart disease as well as in another group of patients, who underwent heart surgery for nonischemic reasons. The response of taurine and glutamine was significantly higher for the patients with ischemic heart disease, in spite of a shorter mean time of heart arrest. No sex differences were recorded. High levels of amino acids coincided frequently with clinical events, which were suggestive of ischemia, but were also recorded in a few patients without diagnosed events. We conclude that monitoring of extracellular amino acids is valuable for evaluation and development of cardioprotective strategies.

The significance of oral health and dental treatment for the postoperative outcome of heart valve surgery.

The objective of this study was to evaluate the significance of preoperative dental treatment for the development of complications in the form of infections during the first postoperative weeks after heart valve surgery. In one group of patients (n = 149), oral health was examined and dental treatment performed 3-6 months prior to heart valve surgery. In a second group (n = 104), oral health was examined postoperatively and these patients did not receive any dental treatment before surgery. Infections were recorded for all patients during the first three weeks after surgery and correlated to the dental status at the time of surgery. Sepsis or endocarditis occurred in 5.4% of the first group and in 1.9% of the second group. Freedom from all infections for the two groups was 55% and 56%, respectively. The results did not reveal any significant differences between the groups regarding patients' oral health at the primary oral examination. The frequencies of postoperative complications such as focal infections, fever and increased CRP were also found to be similar for both groups. The combined scores of complications were 2.1% and 1.8%, respectively. Data from the present study do not support the suggestion that dental intervention will decrease the rate of early complications following heart valve surgery.

Monitoring of extracellular aspartate aminotransferase and troponin T by microdialysis during and after cardioplegic heart arrest.

This study aims at developing per- and postopertive surveillance of the myocardium and focuses on ischemic damage following cardioplegic heart arrest. Levels of troponin T and total aspartate aminotransferase (ASAT) were analyzed in the myocardial interstitium of 10 patients with ischemic heart disease (IHD) who underwent coronary bypass surgery and in 12 patients with nonischemic heart disease (N-IHD) who underwent valvular surgery. Fluid from the myocardial interstitium of the anterior and the lateral wall of the heart was sampled by microdialysis probes that were implanted during surgery and extracted percutaneously 70-100 h later. There were no adverse reactions, and the equipment did not interfere with the surgical procedures. The peak in troponin T serum levels that occurred 4 h after cardiac arrest was preceded by a peak in troponin T levels in the microdialysates from the interstitium that occurred 1 h earlier. The concentration of troponin T in the microdialysate peak was 300 times higher than in the serum peak. The increase in serum ASAT levels during the first 7 h after cardiac arrest corresponded in time with a decrease in interstitial ASAT levels, which had already reached a maximum during cardiac arrest. The microdialysate/serum concentration ratio was considerably smaller for ASAT than for troponin T. Interstitial peak levels of troponin T correlated positively and significantly with peak levels of ASAT. Of the 22 patients, 15 had no postoperative events according to clinical outcome, ECG and serum tests. Fourteen of these had low to normal levels of interstitial ASAT and troponin T. Conversely, atrial fibrillation and/or premature atrial contractions were recorded in 8/22 patients, 7 of whom had elevated interstitial ASAT and/or troponin T concentrations in one or both of the sampled heart regions. The N-IHD patients had higher levels of troponin T in the interstitium 20-70 h following cardioplegia, while the peak levels did not differ between the groups. In conclusion, microdialysis sampling of troponin T and ASAT is safe and allows a highly sensitive analysis of the ischemic trauma exerted by the cardioplegic arrest.

Short- and long-term performance of a tripolar down-sized single lead for implantable cardioverter defibrillator treatment: a randomized prospective European multicenter study. European Endotak DSP Investigator Group.

A new, thinner (10 Fr) and more flexible, single-pass transvenous endocardial ICD lead, Endotak DSP, was compared with a conventional lead, Endotak C, as a control in a prospective randomized multicenter study in combination with a nonactive can ICD. A total of 123 patients were enrolled, 55 of whom received a down-sized DSP lead. Lead-alone configuration was successfully implanted in 95% of the DSP patients vs 88% in the control group. The mean defibrillation threshold (DFT) was determined by means of a step-down protocol, and was identical in the two groups, 10.5 +/- 4.8 J in the DSP group versus 10.5 +/- 4.8 J in the control group. At implantation, the DSP mean pacing threshold was lower, 0.51 +/- 0.18 V versus 0.62 +/- 0.35 V (p < 0.05) in the control group, and the mean pacing impedance higher, 594 +/- 110 omega vs 523 +/- 135 omega (p < 0.05). During the follow-up period, the statistically significant difference in thresholds disappeared, while the difference in impedance remained. Tachyarrhythmia treatment by shock or antitachycardia pacing (ATP) was delivered in 53% and 41%, respectively, of the patients with a 100% success rate. In the DSP group, all 28 episodes of polymorphic ventricular tachycardia or ventricular fibrillation were converted by the first shock as compared to 57 of 69 episodes (83%) in the control group (p < 0.05). Monomorphic ventricular tachycardias were terminated by ATP alone in 96% versus 94%. Lead related problems were minor and observed in 5% and 7%, respectively. In summary, both leads were safe and efficacious in the detection and treatment of ventricular tachyarrhythmias. There were no differences between the DSP and control groups regarding short- or long-term lead related complications.

Automatic adjustment of pacemaker stimulation output correlated with continuously monitored capture thresholds: a multicenter study. European Microny Study Group.

Pacing threshold is affected by many factors. A pacing system able to confirm capture at each beat and automatically adjust its output close to the actual pacing threshold is highly desirable. This study evaluates the safety and efficacy of the Autocapture function of the Pacesetter Microny SR+. One hundred thirteen patients were recruited from 16 centers in 7 European countries and followed up for 1 year. All pacemakers were implanted with Pacesetter's low polarization, bipolar leads. The key feature of Autocapture is the immediate delivery of a 4.5 V safety backup pulse 62.5 ms after any ineffective ongoing low output pulse. Holter recordings confirmed total reliability of this feature without any exit block. The measured evoked response (ER) signal was stable over time. Acute and chronic pacing thresholds measured by VARIO and Autocapture tests correlated (r > 0.79) over the period of the study. The incidence of backup pulses was 1.1% during pacing. With Autocapture programmed ON, the overall total current consumption was 4.1 microA for VVI and 5.0 microA for VVIR pacing. This study proved that the Autocapture safely and reliably regulates the pacemaker's output according to the prevailing threshold thus providing maximum patient safety and prolonging service life.

First European experience using excimer laser for the extraction of permanent pacemaker leads.

UNLABELLED: An Excimer Laser system for the extraction of permanent pacemaker leads has been developed by Spectranetics Inc. and Dr. Charles L. Byrd. The laser energy is emitted at the tip of a flexible, fiberoptic 12F sheath that permits the removal of leads with a max. outer diameter of 7.1F. The CVX-300 Excimer Laser source is a xenon chloride laser with an output of 308 nm not visible to the human eye. This cool cutting laser has an absorption depth of 0.06 mm, the energy being absorbed by proteins and lipids. In clinical practice this means that the fibrotic sheaths usually surrounding the leads can be cut without damaging the endothelial wall or the insulation of leads, due to these characteristics the sheath can, however, not pass over tines. For the freeing of lead tips, locking stylets and outer sheaths are combined to perform counter traction. RESULTS: From 8/96 to 5/97 50 leads (38 atrial, 12 ventricular) from 45 patients (22 females, 23 males, mean age 65.1 years, range 32-94) were extracted using the Excimer Laser at our institution. Mean lead implantation time was 47.7 months (range 10.5-351.7). Indication for extraction was suspected J-wire fracture in 16 leads, prophylactic in 8 leads, infection in 12 leads, exit block in 4 leads and other reasons in 10 leads. Mean extraction time, excluding reimplantation, was 10 minutes (range 1-50). The objective of the procedure (normally complete lead removal) was accomplished in all cases but three. All intended lead replacements were successful. No complications occurred. All patients left the hospital in good condition, one patient died, within 30 days due to progressive heart failure. CONCLUSIONS: Lead extraction with Excimer Laser seems to be a safe and efficacious procedure. However, due to the inherent risks appropriate training and experience are essential. If the initial promising results can be maintained, indications for the removal of permanent pacing leads may widen considerably.

In situ detection of myocardial infarction in pig by measurements of aspartate aminotransferase (ASAT) activity in the interstitial fluid.

Microdialysis probes permeable to large molecules (m.w. cut-off > 200 kD) were introduced into the myocardium of anaesthetized pigs in order to evaluate their potential for early detection of myocardial ischaemia and enzyme markers for infarction. The left anterior descending coronary artery was occluded for 30 min and the myocardium was reperfused for 3 h. The concentrations of aspartate aminotransferase (ASAT), lactate, glucose and selected free amino acids were measured. The levels in the interstitium of ischaemic and non-ischaemic myocardium were compared with those in plasma from the coronary sinus as well as from a peripheral vein. Twelve probes were inserted in six pigs and withdrawn after 8-72 hours of sampling. No complications occurred. Simultaneous 100% increase of ASAT and lactate was found in myocardial dialysates after 30 min of ischaemia. ASAT activity remained at that level until the end of reperfusion. The plasma peak ASAT level was not attained until after 3 h. Glutamate was the only amino acid which increased significantly in the myocardial interstitium during ischaemia, peaking after 30 min of reperfusion. Dialysates from the unaffected myocardium showed no effects on lactate, ASAT or glutamate. The use of myocardial microdialysis for pre- and postoperative recordings in man is discussed.

Impact of implant techniques on complications with current implantable cardioverter-defibrillator systems.

Implantable cardioverter-defibrillator (ICD) treatment has been in use since 1980 to prevent sudden cardiac death. The high efficacy of the original epicardial systems to terminate tachyarrhythmias was impaired by a substantial perioperative mortality and morbidity. The more "modern" transvenous ICD systems have shown a similar high efficacy in terminating ventricular tachyarrhythmias, but with a lower mortality and morbidity. As a background for discussing the impact on complications with present transvenous implantation techniques, the literature was reviewed. A large pacemaker series was used for comparison. Lead complications clearly related to design, material, or manufacture were not reviewed. The present review, covering 107 references over 40 years, gives support for the notion that in transvenously implanted ICD patients the incidence of acute and late complications related to implantation technique is now acceptable. The rate of hematomas, symptomatic thromboembolic complications, perforations, and to a certain degree infections could be improved, however. The major risk factors for implantation-related complications are discussed, and suggestions for future improvement are given.

Atrial myxomas: results of 25 years' experience and review of the literature.

Twenty patients with atrial myxoma from a 25-year period were reviewed. Sixteen patients had a tumor in the left atrium, three in the right, and one had a biatrial myxoma. The main clinical presentations were dyspnea and tachyarrhythmias seen in 11 patients. Nineteen patients had a correct preoperative diagnosis. Echocardiography confirmed the diagnosis in eight patients, angiocardiography in four, and both these techniques in seven. The diagnosis was established at the operative table in one case in which the preoperative diagnosis was mitral stenosis. All tumors were successfully removed with cardiopulmonary bypass. There were no operative deaths. Excision of the tumor resulted in marked symptomatic improvement. No recurrences have been observed. A differential approach to preoperative investigation, surgical treatment, and follow-up is suggested according to the clinical behavior of the tumor. Excision of the tumor appears to be curative, with no recurrences at long-term follow-up in cases of "sporadic" myxoma. The risk of recurrences is much higher when a "complex" or a "familial" myxoma is faced. For these types, our recommendations are presented.