ORIGINAL ARTICLE
Endovascular extraction techniques Part 3: Results and indications in patients with
an
lCD
F.A. Bracke, A. Meijer, B. van Gelder
Introduction. We report our experience with lead extraction in patients with an implantable cardioverter defibrillator (ICD) and discuss the indications for extraction in these patients. Patients. Eighteen patients with an ICD (mean age 58±12 years) were referred for lead extraction: two patients with infection and 16 with lead dysfunction. Methods. Lead extraction was performed with a laser sheath (Excimer) if traction with a locking device was insufficient. New leads were implanted during the same procedure, if applicable. Results. Shock leads were successfully extracted in 16 patients and additional pace-sense leads in seven patients. In two patients, the shock conductor was considered unaffected and only a pace-sense lead was exchanged or an additional pace-sense lead inserted. After extraction, new shock leads were implanted in 14 patients. Major complications occurred in one patient: a pericardial tamponade after perforation of the superior caval vein necessitating acute surgery. Conclusion. Lead extraction with a laser sheath is effective in ICD patients, but major complications can occur. Our current policy with malfunctioning leads is to extract all leads in which insulation defects cannot be ruled out to avoid interference, but to abandon leads that are without insulation defects and properly insulated. In case of infection, extraction remains the primary treatment ofchoice.
(Neth HeartJ2001;9:117-22.) Key words: implantable cardioverter defibrillator, laser sheath, lead extraction F.A. Bracke. A. Meijer. B. van Gelder. Department of Cardiology, Catharina Hospital, P0 Box 1350, 5602 Z4 Eindhoven. Address for correspondence: F.A. Bracke. E-mail: [email protected]
Netherlands Heart Joumal, Volume 9, Number 3, June 2001
W ith the increase in the numbers of ICDs being implanted, physicians will increasingly be confronted with lead complications with these devices and the suitability oflead extraction. Although most indications for extraction of pacing leads apply to endocardial ICD leads as well, the high voltage shock for defibrillation poses separate considerations. We discuss lead malfunction in ICD patients and the consequences for lead extraction, but first describe our own experience. Patients From October 1998 until November 2000, 18 ICD patients (12 male, mean age 58±12 years) were referred to our centre for lead extraction. The time from implant was 32±21 months (median 28, range 10-99). The indications for referral were infection in two patients and lead malfinction in 16 patients (table 1). In three patients, lead malfimction was associated with twiddler's syndrome. There were previous extraction attempts in four patients: two were unsuccessful attempts at removing an ICD lead and two were successful in removing an atrial pace-sense lead. Methods A venous phlebography was acquired before the procedure to assess patency of the vein and extent of fibrous tissue around the lead. All procedures were performed in the operating room under general anaesthesia with the patient prepared for thoracotomy and during transoesophageal echocardiographic monitoring. First gentle traction with a locking stylet was applied, taking care not to disrupt the lead or the locking stylet. If the lead tip dislocated but could not be pulled out easily, it was approached from the femoral vein with a retriever system and a femoral workstation to prevent entrapment by fibrous adhesions. If traction was not successful, a laser sheath (Spectranetics, Co) with a synthetic outer sheath was inserted over the lead. A 12 or 14 F laser sheath was used for pace-sense leads and a 16 F for shock leads. Laser energy was provided by an Excimer Xenon117
Endovascular extraction techniques
Table 1. Lead characteristics and results of extraction. Patient Lead no. no.
Pacing capabilly
Lead type
Lead function
Lead Presenting location lead defect
CPI 0125
D
V
Medtronic 6940
P/S
A
Time from inplants (months)
generator 1
1
DDDR
2
2
3
WIR
Medtronic 6936
D
V
3
4
DDDR
CPI 4245
P/S
V
4
5 6 7
WIR
CPI 4269 CPI 0125 Telectronics 104068
P/S D D
A V V
5
8 9
Telectronics 104069 CPI 0125
D D
A V
6
10 11
DDDR
Medtronic 6943 CPI 4244
D P/S
V A
7
12
WIR
CPI 0125
D
V
P/S
A
P/S
V
8
13
WIR
Medtronic 6936
D
V
9
14
DDDR
CPI 4244
P/S
A
Medtronic 6943
D
V
15 10
16
WIR
CPI 0125
D
V
11
17
DDDR
Medtronic 6940
P/S
A
12
18 19
WIR
Medtronic 6945 Medtronic 6936
D D
V V
13
20
DDDR
CPI 4269
P/S
A
CPI 0125
D
V
isolation defect detected during revision, previous extraction attempt decreased impedance, increased pacing threshold, decreased sensing isolation damage during generator exchange, previous extraction attempt oversensing
Extraction Leads technique implanted laser traction*
none none oversensing, inappropriate shocks none decreased shock impedance, increased pacing impedance oversensing already removed during previous procedure increased pacing impedance and threshold already abandoned during ICD implantation already abandoned during ICD implantation oversensing, inappropriate shocks oversensing, increased pacing threshold, twiddler incresed pacing threshold, twiddler increased sensing threshold, decreased pacing impedance, twiddler increased pacing threshold and impedance, twiddler
312 312 42
laser
ventricular defibrillation
laser
ventricular pace-sense
reused reused laser
312
atrial pace-sense, ventricular abandoned defibrillation laser ventricular defibrillation laser atrial pace-sense, traction* ventricular defibrillation laser atrial pace-sense, ventricular abandoned defibrillation
312
abandoned
38
laser
ventricular
13
LS
13
LS /FWS
defibrillation atrial pace-sense, ventricular defibrillation
26
laser
ventricular defibrillation
10
laser
atrial pace-sense, ventricular defibrillation
10 36
reused
34
laser
ventricular pace-sense atrial pace-sense, ventricular defibrillation
34
laser
19
laser
ventricular defibrillation
laser/
none
42 29 11 11 41
A/V ICD
21 14
22
WIR
Medtronic 6943
D
V
15
23
WIR
Medtronic 6966
D
V
16 17 18
24 25 26 27 28 29 30 31
DDDR
DDDR
CPI 15 Medtronic 6942 Medtronic 6940 Medtronic 13014-58 CPI 0125 CPI 4245 CPI 4269 Medtronic 6943
D D
P/S D P/S P/S D
V V A SC V V A V
twiddler no capture, increased impedance, _ _ oversensing, increased pacing impedance and threshold
oversensing, increased pacing impedance and threshold oversensing, increased pacing impedance and threshold, shock impedance not available infection
100
infection infection infection infection
1 27 27
none
50 50 47 11
oversensing oversensing twiddler, increased sensing threshold, increased pacing threshold
atrial pace-sense, ventricular defibrillation
surgical traction laser traction
none
27_ laser traction traction traction
atrial pace-sense, ventricular defibrillation ventricular defibrillation
A: atrial; SC: subcutaneous; V: ventricular; D: defibrillation; P/S: pace-sense; WIR: one-chamber pacing capability; DDDR: dual-chamber pacing capability; A/V ICD: dual-chamber defibrillator. * Extracted during previous procedure.
18
Netherlands Heart Journal, Volume 9, Number 3, June 2001
Endovascular extraction techniques
chloride laser with a wavelength of 308 nm and repetition rate of4O Hz and energy flux of 60 mJ/mm2 (Spectranetics, Co). During extraction, the laser sheath was advanced using the lead as a guide wire. The outer sheath followed to support manipulation of the laser sheath or preceded it if only minor resistance was encountered. If the tip of the lead was not yet free by the time the sheaths reached the myocardium, countertraction was applied with the outer sheath positioned against the myocardium to prevent inversion during traction. If new leads needed to be inserted, both laser sheath and lead were removed whilst the outer sheath was kept in position after the lead dislocated from the myocardium. One or two 150 cm. long 0.035-inch guide wires were introduced before removal of the outer sheath to secure access to the central venous circulation. Subsequently, a peel-away sheath was inserted over the guide wire and new leads inserted in a standard manner. Results In two patients we reused the shock lead: in one an additional pace-sense electrode inserted during a previous revision was exchanged as the shock electrode fimctioned normally, in the second the defect could be localised to the connector of the pace-sense electrode of a single pass lead and insulated (table 1). As the shock electrode functioned normally, an additional ventricular pace-sense lead was inserted. The original lead was reused as shock electrode in both patients. In the other 16 patients, ICD leads were extracted; in one patient two leads were extracted. Thirteen ICD leads were removed with a laser sheath, two with traction, one with a femoral workstation (after the lead had dislocated during traction but could not be pulled through adhesions in the brachiocephalic vein) and one surgically after tamponade caused by laser sheath extraction.
Netherlands Heart Joumal, Volume 9, Number 3, June 2001
Seven pace-sense leads were also extracted including three with a laser sheath. Preoperative phlebography showed asymptomatic occlusion of the left subclavian and brachiocephalic vein in two of the 18 patients. Fourteen new defibrillator leads and ten pace-sense leads were implanted through an exchange procedure or through recatheterisation ofthe subclavian vein (in the patient in whom a femoral workstation was used). In both patients with infection no new leads were implanted during the extraction procedure. The same ICD generator was reimplanted in seven patients while nine received a new device. A rare observation was made in the only patient presenting with abnormally low shock impedance. The lead was extracted and a new single transvenous defibrillator lead implanted. After satisfactory testing of the pacing and sensing parameters it was connected to the original ICD. During test shocks with the device, measurements of the shock impedance again yielded an abnormally low value. After replacing the generator as well, the shock impedance ofthe new lead was within normal limits. Later inspection showed an insulation defect in the proximal part of the removed lead and signs of arcing on the defibrillator. We postulated that a short circuit at the time of a shock had damaged the generator circuitry resulting in a false reading of the
impedance. A pocket haematoma necessitated reoperation in one patient. Laceration of the superior caval vein during a laser procedure resulted in acute pericardial tamponade in another patient. Acute surgery with the use of extracorporal circulation was necessary to repair the defect. The patient recovered with no sequelae. The total average procedure time was 162±72 min. Discussion Until now, extraction of ICD leads has only been reported in a limited number of patients.'-5 Le Franc 119
Endovascular extraction techniques
et al. reported successful endovascular extraction of 13 defibrillation leads using telescoping dilator sheaths in five patients and a femoral approach in six leads.2'6 Vassilikos et al. reported extraction offour shock leads with a locking stylet although in one lead a femoral approach was necessary.4 With a laser sheath, Krishnan et al. described successful extraction of defibrillator leads in ten patients and Kennergren et al. in 15 out of 16 patients.3'5 We extracted all shock leads successfully in 16 patients: in 13 patients with an approach including a laser sheath, and in one patient the lead was further removed during surgery for tamponade complicating laser sheath extraction. There are no comparative studies of conventional extraction techniques vs. laser sheath extraction. In pacemaker patients, the laser performed more predictably during initial extraction attempts than the conventional techniques but the final results did not differ in large registries of both techniques.79 Only Krishnan et al. reported a major complication ofICD lead extraction in a patient during laser sheath extraction.3 They performed lead extraction in the catheterisation room and although the patient was transferred to the operating room for emergency surgery after tamponade, severe neurological damage led to his demise. We encountered one tamponade: as our procedures were carried out in the operating room under general anaesthesia with the patient prepared for thoracotomy, the bleeding could be swiftly controlled and the patient recovered without sequelae. These reports are too limited to judge the real incidence of complications. It has been stated that extensive fibrous tissue growing into the grooves of the defibrillation coils could make extraction of ICD leads more difficult.3 10 Therefore, it is safe to assume that complications will be no less than with pacing leads where major complications occur in between 1.4% and 3.5% of procedures with a mortality of 0% to 0 8% 5,8,9,11
Regarding infection, the same considerations for lead extraction in pacemaker leads apply to ICD patients. Extraction of all hardware has the best chance of curing a device-related infection.'2 In a policy statement, NASPE advocates the removal of all malfunctioning ICD leads when interference poses a threat to the patient, but these conditions are still largely undetermined and not fully evaluated.'3 Mechanical dysftmction of either endocardial shock or pace-sense leads (excluding dislodging, increased thresholds and loose set screws) occurs in between 0 and 3% of ICD patients in papers reporting on more than 150 patients (table 2).14-24 Interestingly, the most commonly mentioned defect in defibrillator leads is malfunction ofthe pacesense conductors. This discrepancy between pace-sense and shock conductor may indicate a true lower complication rate of the shock conductors, or it may reflect the difficulty to detect a defective insulation or 120
conductor of the shock lead. Until recently, the only available test of the shock conductor was shock impedance measured after a spontaneous or test shock. But a typical insulation defect will have high impedance compared with the low impedance of the shock coil. Any aberration may therefore fall within normal serial changes in defibrillation lead impedance and can be missed during routine follow-up.25 An interruption of the high voltage conductor is expected to result in increased impedance. However, normal impedance of the high voltage circuit during a high voltage shock has been reported, only becoming abnormally high when measured at 5 volt with a pacing system analyser or at low energy high voltage test shocks.26'27 A high voltage shock ofsufficient energy is probably able to 'jump' a lead fracture resulting in shock delivery with an apparent normal impedance. This stresses the need for more sensitive and easily applicable methods for measuring high voltage conductor integrity. Mehdirad et al. showed that calculated impedance measurements using delivery of low voltage subthreshold stimuli are highly correlated to impedance measured during shock delivery.28 A similar low voltage test is now incorporated in present ICDs and may allow for a more reliable control of the continuity of the shock conductor than test shocks during lead revision.29 Exceptionally, a generator dysfunction can be responsible for changes in the measured shock lead impedance. One of our patients presented with an abnormally low shock impedance. When a new ICD lead was inserted, the same low impedance was measured again and we obtained normal shock impedance only after replacing the generator. An insulation defect close to the generator had resulted in a short circuit damaging the generator circuitry, thus causing a false reading of the impedance. Gummert et al. described a similar situation but with the insulation defect in the proximal part of the sensing lead.30 In both cases, the generator circuitry could not withstand the high load caused by the short circuit current. Malfunctioning or redundant leads can then either be extracted or abandoned, sometimes in a separate pocket.31'32 There is, however, a possibility of interference with both pace-sense function and defibrillation. Direct mechanical contact between endocardial leads may generate spurious electrical potentials resulting in inappropriate shocks or inhibition of pacing.33'34 To avoid contact, a new shock lead may be placed in the right ventricular outflow tract, but this can significantly increase the energy requirements for defibrillation compared with a right ventricular apical position.35'36 True bipolar leads should be less prone to this complication as the sensing electrodes are closely spaced and contact can be more easily avoided. Contact between two leads by adjacent coils or insulation defects may potentially interfere with the defibrillation threshold. The latter was not affected in an animal model, whether or not the active electrode Netherlands Heart Joumal, Volume 9, Number 3, June 2001
Endovascular extraction techniques
touched a passive electrode of an abandoned lead.37 However, these data are restricted to intact, insulated electrodes and a short circuit may occur during a shock if there is an insulation defect or the connector is not properly capped.27 The risk of venous occlusion with multiple leads was not an indication for extraction in our patients. Although there are incidental reports on superior vena cava occlusion, there are no data indicating an excess risk of venous occlusion in the presence of multiple ICD leads.34'38-40 Further, the risk of venous occlusion from lead extraction itself is uncharted. Preoperative phlebography is important to reveal asymptomatic venous obstruction, which occurred in two out of the 18 patients. In this situation we prefer to extract a single non-functional lead and insert new leads through an exchange procedure. This preserves the opposite pectoral site for future use in the event of complications, and prevents bilateral occlusion. Although right-sided pectoral implantation is an alternative, a higher defibrillation threshold has been reported.41-45 Conclusion Although we and other authors have good results from lead extraction in ICD patients, it has only been performed in a limited number of patients and not without complications. In the event of infection, lead extraction remains the therapy ofchoice in patients in whom the risk ofextraction is considered low. Until more data become available on the safety of lead extraction, it appears to be safe to leave malfunctioning leads in ICD patients in situ on the condition that insulation defects are excluded or properly insulated, and with the connector pin adequately capped.31'32 Under these conditions, a separate pace-sense lead can be inserted if damage to the shock conductor is excluded in case ofpace-sense malfunction only. The original lead can then be reused as a shock electrode.'8'46 In all other instances, given the consequences offailed ICD therapy, it is probably safer to extract any damaged or suspected pace-sense or shock lead. -
7 8 9
10 11 12 13
14
15
16
17
18 19
20 21
22
References 1 2
3 4
5 6
Jordaens L, Belleghem Y van, Herregods L. Removal of endocardial defibrillation leads. Pacing Clin Electrophysiol 1996;19:127-9. Le Franc P, Klug D, Jarwe M, et al. Extraction ofendocardial implantable cardioverter-defibrillator leads. Am J Cardiol 1999;84: 187-91. Krishnan SC, Epstein LM. Initial experience with a laser sheath to extract chronic transvenous implantable cardioverter-defibrillator leads. AmJ Cardiol 1998;82:1293-5. Vassilikos VP, Maounis TN, Chiladakis J, Cokkinos DV, Manolis AS. Percutaneous extraction oftransvenous defibrillator leads using the VascoExtor pacing lead removal system. J Interv Card Electrophysiol 1999;3:247-51. Kennergren C. Excimer laser assisted extraction of permanent pacemaker and ICD leads: present experiences of a European multicentre study. EurJ Cardiothorac Surg 1999;15:856-60. Le Franc P, Klug D, Jarwe M, et al. Extraction and reimplantation of defibrillation leads through a thrombotic subclavian vein.
Netherlands Heart Joumal, Volume 9, Number 3, June 2001
23
24
25
26
27
Pacing Clin Electrophysiol 1999;22:977-8. WikoffBL, Byrd CL, Love CJ, et al. Pacemaker lead extraction with the laser sheath: results of the pacing lead extraction with the excimer sheath (PLEXES) trial. JAm Coll Cardiol 1999;33:1671-6. Smith HJ, Fearnot NE, Byrd CL, WilkoffBL, Love CJ, Sellers TD. Five-years experience with intravascular lead extraction. U.S. Lead Extraction Database. Pacing Clin Electrophysiol 1994;17:2016-20. Byrd CL, WikoffBL, Love CJ, et al. Intravascular extraction of problematic or infected permanent pacemaker leads: 1994-1996. U.S. Extraction Database, MED Institute. Pacing Clin Electrophysiol 1999;22:1348-57. EpsteinAE, Kay GN, Plumb VJ, DaileySM,Anderson PG. Gross and microscopic pathological changes associated with nonthoracotomy implantable defibrillator leads. Circulation 1998;98:1517-24. Reiser C, Byrd CL, WikoffBL, et al. Pacing Lead Extraction With the Excimer Sheath Trial: Final Report [abstract]. Pacing Clin Ekctrophysiol 1998;22:708. Bracke FA, MeijerA, Gelder B van. Pacemaker lead complications: when is extraction appropriate and what can we learn from published data? Heart 2001;85:254-9. Love CJ, WilkoffBL, Byrd CL, et al. Recommendations for extraction of chronically implanted transvenous pacing and defibrillator leads: indications, facilities, training. North American Society of Pacing and Electrophysiology Lead Extraction Conference Faculty. Pacing Clin Electrophysiol 2000;23:544-51. Stambler BS, Wood MA, Damiano RJ, Greenway PS, Smutka ML, Ellenbogen KA. Sensing/pacing lead complications with a newer generation implantable cardioverter-defibrillator: worldwide experience from the Guardian ATP 4210 clinical trial. JAm Coll Cardiol 1994;23:123-32. Schwartzman D, Nallamothu N, Callans DJ, Preminger MW, Gottieb CD, Marchlinski FE. Postoperative lead-related complications in patients with nonthoracotomy defibrillation lead systems. JAm Coll Cardiol 1995;26:776-86. Fahy GJ, Kleman JM, WIkoffBL, Morant VA, Pinski SL. Low incidence of lead related complications associated with nonthoracotomy implantable cardioverter defibrillator systems. Pacing Clin Electrophysiol 1995;18:172-8. Jones GK, Bardy GH, Kudenchuk PJ, et al. Mechanical complications after implantation of multiple-lead nonthoracotomy defibrillator systems: implications for management and future system design. Am HeartJ 1995;130:327-33. Lawton JS, Ellenbogen KA, Wood MA, et al. Sensing lead-related complications in patients with transvenous implantable cardioverter-defibrillators. Am J Cardiol 1996;78:647-51. Gupta A, Zegel HG, Dravid VS, Nierenberg SJ, Freiman DB. Value of radiography in diagnosing complications of cardioverter defibrillators implanted without thoracotomy in 437 patients. Am JRoentgenol 1997;168:105-8. Bardy GH, Yee R, Jung W. Multicenter experience with a pectoral unipolar implantable cardioverter-defibrillator. Active Can Investigators. JAm Coll Cardiol 1996;28:400-10. Gold MR, Peters RW, Johnson JW, Shorofsky SR Complications associated with pectoral implantation of cardioverter defibrillators. World-Wide Jewel Investigators. Pacing Clin Electrophysiol 1997; 20:208-11. Tyers GF, Sanders R, Jacqmein W. Reliability of coated wire defibrillation leads. Pacing Clin Electrophysiol 1999;22:174-8. Gallik DM, Ben Zur UM, Gross JN, Furman S. Lead fracture in cephalic versus subclavian approach with transvenous implantable cardioverter defibrillator systems. Pacing Clin Electrophysiol 1996; 19:1089-94. Drucker EA, Brooks R, Garan H, et al. Malfunction of implantable cardioverter defibrillators placed by a nonthoracotomy approach: frequency of malfunction and value ofchest radiography in determining cause. AmJRoentgenol 1995;165:275-9. Schwartzman D, Hull ML, Callans DJ, Gottlieb CD, Marchlinski FE. Serial defibrillation lead impedance in patients with epicardial and nonthoracotomy lead systems. J Cardiovasc Electrophysiol 1996;7:697-703. Epstein AE, Shepard RB. Failure of one conductor in a nonthoracotomy implantable defibrillator lead causing inappropriate sensing and potentially ineffective shock delivery. Pacing Clin Electrophysiol 1993;16:796-800. Haddad L, Padula LE, Moreau M, Schoenfeld MH. Troubleshooting implantable cardioverter defibrillator system malfunc-
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Endovascular extraction techniques
28
29
30 31
32
33
34
35
36
37
tions: the role of impedance mcasurements. Pacing Clin Electrophysiol 1994;17:1456-61. Mehdirad AA, Stohr EC, Love CJ, Nelson SD, Schaal SF. Implantable defibrillators impedance measurement using pacing pulses versus shock delivery with intact and modified high voltage lead system. Pacing Clin Electrophysiol 1999;22:437-41. Stevens J, Buchwald AB, Krieglstein H, Unterberg C. Early detection of lead fracture by painless high voltage lead impedance measurement in a transvenous ICD lead system. JInterv Card Electrophvsiol 2000;4:269-72. Gummert J, Krauss B, Hutschenreiter W, Hambrecht R, Mohr FW. Sensing lead insulation defect resulting in a damage of the ICD pulse generator case. Pacing Clin Electrophysiol 1998;21:478-9. Mehta D, Nayak HM, Singson M, et al. Late complications in patients with pectoral defibrillator implants with transvenous defibrillator lcad systems: high incidence of insulation breakdown. Pacing Clin Electrophysiol 1998;21:1893-900. Daoud EG, Man KC, Morady F, Strickberger SA. Rise in chronic defibrillation energy requirements necessitating implantable defibrillator lead system revision. Pacing Clin Electrophvsiol 1997;20: 714-9. Pfitzner P, Trappe HJ. Oversensing in a cardioverter defibrillator system caused by interaction between two endocardial defibrillation leads in the right ventricle. Pacing Clin Electrophvsiol 1998; 21:764-8. Nunain SO, Roelke M, Trouton T, et al. Limitations and late complications of third-generation automatic cardioverter-defibrillators. Circulation 1995;91:2204-13. Tang AS, Hendry P, Goldstein W, Green MS, Luce M. Nonthoracotomy implantation of cardioverter defibrillators: preliminary experience with a defibrillation lead placed at the right ventricular outflow tract. Pacing Clin Electrophysiol 1996;19:960-4. Winter J, Heil JE, Schumann C, et al. Effect of implantable cardioverter/defibrillator lead placement in the right ventricle on defibrillation energy requirements. A combined experimental and clinical study. EurJ Cardiothorac Surg 1998;14:419-25. Fotuhi PC, KenKnight BH, Melnick SB, Smith WM, Baumann
122
38
39 40 41 42 43
44
45
46
GF, Ideker RE. Effect of a passive endocardial electrode on defibrillation efficacy of a nonthoracotomy lead system. JAm Coll Cardiol 1997;29:825-30. Minen G, Proclemer A, Facchin D. Asymptomatic supcrior vena caval occlusion: a complication of nonthoracotomy implantation of cardioverter defibrillator. Pacing Clin Electrophysiol 1998;21: 1676-8. Dhondt E, Hutse W, Vanmeerhaeghe X, Jordaens L. Superior vena cava syndrome after implantation of a transvenous cardioverter defibrillator. Eur HeartJ 1995;16:716-8. Pacifico A, Wheelan KR, Nasir N Jr, et al. Long-term follow-up ofcardioverter-defibrillator implanted under conscious sedation in prepectoral subfascial position. Circulation 1997;95:946-50. Jensen SM, Pietersen A, Chen X. Implantation of active can implantable defibrillators in the right pectoral region. Pacing Clin Electrophysiol 1998;21:476-7. Natale A, Sra J, Geiger MJ, Newby K, Akhtar M, Pacifico A. Right side implant of the unipolar single lead defibrillation system. Pacing Clin Electrophysiol 1997;20:1910-2. Schofield IJ, Rankin I, Bennett DH. Right sided pectoral implantation of an 'active can' transvenous implantable cardioverter-defibrillator with single right ventricular lead. Br Heart J 1995;74:204. Epstein AE, Kay GN, Plumb VJ, Voshage-Stahl L, Hull ML. Elevated defibrillation threshold when right-sided venous access is used for nonthoracotomy implantable defibrillator lead implantation. The Endotak Investigators. JCardiovascElcctrophysiol 1995; 6:979-86. Friedman PA, Rasmussen MJ, Grice S, Trusty J, Glikson M, Stanton MS. Defibrillation thresholds are increased by right-sided implantation of totally transvenous implantable cardioverter defibrillators. Pacing Clin Electrophysiol 1999;22:1186-92. Lawton JS, Wood MA, Gilligan DM, Stambler BS, Damiano RJ Jr, Ellenbogen KA. Implantable transvenous cardioverter defibrillator leads: the dark side [editorial]. Pacing Clin Electrophysiol 1996;19:1273-8.
Netherlands Heart Joumal, Volume 9, Number 3, June 2001
Endovascular extraction techniques Part 3: Results and indications in patients with
an
lCD
F.A. Bracke, A. Meijer, B. van Gelder
Introduction. We report our experience with lead extraction in patients with an implantable cardioverter defibrillator (ICD) and discuss the indications for extraction in these patients. Patients. Eighteen patients with an ICD (mean age 58±12 years) were referred for lead extraction: two patients with infection and 16 with lead dysfunction. Methods. Lead extraction was performed with a laser sheath (Excimer) if traction with a locking device was insufficient. New leads were implanted during the same procedure, if applicable. Results. Shock leads were successfully extracted in 16 patients and additional pace-sense leads in seven patients. In two patients, the shock conductor was considered unaffected and only a pace-sense lead was exchanged or an additional pace-sense lead inserted. After extraction, new shock leads were implanted in 14 patients. Major complications occurred in one patient: a pericardial tamponade after perforation of the superior caval vein necessitating acute surgery. Conclusion. Lead extraction with a laser sheath is effective in ICD patients, but major complications can occur. Our current policy with malfunctioning leads is to extract all leads in which insulation defects cannot be ruled out to avoid interference, but to abandon leads that are without insulation defects and properly insulated. In case of infection, extraction remains the primary treatment ofchoice.
(Neth HeartJ2001;9:117-22.) Key words: implantable cardioverter defibrillator, laser sheath, lead extraction F.A. Bracke. A. Meijer. B. van Gelder. Department of Cardiology, Catharina Hospital, P0 Box 1350, 5602 Z4 Eindhoven. Address for correspondence: F.A. Bracke. E-mail: [email protected]
Netherlands Heart Joumal, Volume 9, Number 3, June 2001
W ith the increase in the numbers of ICDs being implanted, physicians will increasingly be confronted with lead complications with these devices and the suitability oflead extraction. Although most indications for extraction of pacing leads apply to endocardial ICD leads as well, the high voltage shock for defibrillation poses separate considerations. We discuss lead malfunction in ICD patients and the consequences for lead extraction, but first describe our own experience. Patients From October 1998 until November 2000, 18 ICD patients (12 male, mean age 58±12 years) were referred to our centre for lead extraction. The time from implant was 32±21 months (median 28, range 10-99). The indications for referral were infection in two patients and lead malfinction in 16 patients (table 1). In three patients, lead malfimction was associated with twiddler's syndrome. There were previous extraction attempts in four patients: two were unsuccessful attempts at removing an ICD lead and two were successful in removing an atrial pace-sense lead. Methods A venous phlebography was acquired before the procedure to assess patency of the vein and extent of fibrous tissue around the lead. All procedures were performed in the operating room under general anaesthesia with the patient prepared for thoracotomy and during transoesophageal echocardiographic monitoring. First gentle traction with a locking stylet was applied, taking care not to disrupt the lead or the locking stylet. If the lead tip dislocated but could not be pulled out easily, it was approached from the femoral vein with a retriever system and a femoral workstation to prevent entrapment by fibrous adhesions. If traction was not successful, a laser sheath (Spectranetics, Co) with a synthetic outer sheath was inserted over the lead. A 12 or 14 F laser sheath was used for pace-sense leads and a 16 F for shock leads. Laser energy was provided by an Excimer Xenon117
Endovascular extraction techniques
Table 1. Lead characteristics and results of extraction. Patient Lead no. no.
Pacing capabilly
Lead type
Lead function
Lead Presenting location lead defect
CPI 0125
D
V
Medtronic 6940
P/S
A
Time from inplants (months)
generator 1
1
DDDR
2
2
3
WIR
Medtronic 6936
D
V
3
4
DDDR
CPI 4245
P/S
V
4
5 6 7
WIR
CPI 4269 CPI 0125 Telectronics 104068
P/S D D
A V V
5
8 9
Telectronics 104069 CPI 0125
D D
A V
6
10 11
DDDR
Medtronic 6943 CPI 4244
D P/S
V A
7
12
WIR
CPI 0125
D
V
P/S
A
P/S
V
8
13
WIR
Medtronic 6936
D
V
9
14
DDDR
CPI 4244
P/S
A
Medtronic 6943
D
V
15 10
16
WIR
CPI 0125
D
V
11
17
DDDR
Medtronic 6940
P/S
A
12
18 19
WIR
Medtronic 6945 Medtronic 6936
D D
V V
13
20
DDDR
CPI 4269
P/S
A
CPI 0125
D
V
isolation defect detected during revision, previous extraction attempt decreased impedance, increased pacing threshold, decreased sensing isolation damage during generator exchange, previous extraction attempt oversensing
Extraction Leads technique implanted laser traction*
none none oversensing, inappropriate shocks none decreased shock impedance, increased pacing impedance oversensing already removed during previous procedure increased pacing impedance and threshold already abandoned during ICD implantation already abandoned during ICD implantation oversensing, inappropriate shocks oversensing, increased pacing threshold, twiddler incresed pacing threshold, twiddler increased sensing threshold, decreased pacing impedance, twiddler increased pacing threshold and impedance, twiddler
312 312 42
laser
ventricular defibrillation
laser
ventricular pace-sense
reused reused laser
312
atrial pace-sense, ventricular abandoned defibrillation laser ventricular defibrillation laser atrial pace-sense, traction* ventricular defibrillation laser atrial pace-sense, ventricular abandoned defibrillation
312
abandoned
38
laser
ventricular
13
LS
13
LS /FWS
defibrillation atrial pace-sense, ventricular defibrillation
26
laser
ventricular defibrillation
10
laser
atrial pace-sense, ventricular defibrillation
10 36
reused
34
laser
ventricular pace-sense atrial pace-sense, ventricular defibrillation
34
laser
19
laser
ventricular defibrillation
laser/
none
42 29 11 11 41
A/V ICD
21 14
22
WIR
Medtronic 6943
D
V
15
23
WIR
Medtronic 6966
D
V
16 17 18
24 25 26 27 28 29 30 31
DDDR
DDDR
CPI 15 Medtronic 6942 Medtronic 6940 Medtronic 13014-58 CPI 0125 CPI 4245 CPI 4269 Medtronic 6943
D D
P/S D P/S P/S D
V V A SC V V A V
twiddler no capture, increased impedance, _ _ oversensing, increased pacing impedance and threshold
oversensing, increased pacing impedance and threshold oversensing, increased pacing impedance and threshold, shock impedance not available infection
100
infection infection infection infection
1 27 27
none
50 50 47 11
oversensing oversensing twiddler, increased sensing threshold, increased pacing threshold
atrial pace-sense, ventricular defibrillation
surgical traction laser traction
none
27_ laser traction traction traction
atrial pace-sense, ventricular defibrillation ventricular defibrillation
A: atrial; SC: subcutaneous; V: ventricular; D: defibrillation; P/S: pace-sense; WIR: one-chamber pacing capability; DDDR: dual-chamber pacing capability; A/V ICD: dual-chamber defibrillator. * Extracted during previous procedure.
18
Netherlands Heart Journal, Volume 9, Number 3, June 2001
Endovascular extraction techniques
chloride laser with a wavelength of 308 nm and repetition rate of4O Hz and energy flux of 60 mJ/mm2 (Spectranetics, Co). During extraction, the laser sheath was advanced using the lead as a guide wire. The outer sheath followed to support manipulation of the laser sheath or preceded it if only minor resistance was encountered. If the tip of the lead was not yet free by the time the sheaths reached the myocardium, countertraction was applied with the outer sheath positioned against the myocardium to prevent inversion during traction. If new leads needed to be inserted, both laser sheath and lead were removed whilst the outer sheath was kept in position after the lead dislocated from the myocardium. One or two 150 cm. long 0.035-inch guide wires were introduced before removal of the outer sheath to secure access to the central venous circulation. Subsequently, a peel-away sheath was inserted over the guide wire and new leads inserted in a standard manner. Results In two patients we reused the shock lead: in one an additional pace-sense electrode inserted during a previous revision was exchanged as the shock electrode fimctioned normally, in the second the defect could be localised to the connector of the pace-sense electrode of a single pass lead and insulated (table 1). As the shock electrode functioned normally, an additional ventricular pace-sense lead was inserted. The original lead was reused as shock electrode in both patients. In the other 16 patients, ICD leads were extracted; in one patient two leads were extracted. Thirteen ICD leads were removed with a laser sheath, two with traction, one with a femoral workstation (after the lead had dislocated during traction but could not be pulled through adhesions in the brachiocephalic vein) and one surgically after tamponade caused by laser sheath extraction.
Netherlands Heart Joumal, Volume 9, Number 3, June 2001
Seven pace-sense leads were also extracted including three with a laser sheath. Preoperative phlebography showed asymptomatic occlusion of the left subclavian and brachiocephalic vein in two of the 18 patients. Fourteen new defibrillator leads and ten pace-sense leads were implanted through an exchange procedure or through recatheterisation ofthe subclavian vein (in the patient in whom a femoral workstation was used). In both patients with infection no new leads were implanted during the extraction procedure. The same ICD generator was reimplanted in seven patients while nine received a new device. A rare observation was made in the only patient presenting with abnormally low shock impedance. The lead was extracted and a new single transvenous defibrillator lead implanted. After satisfactory testing of the pacing and sensing parameters it was connected to the original ICD. During test shocks with the device, measurements of the shock impedance again yielded an abnormally low value. After replacing the generator as well, the shock impedance ofthe new lead was within normal limits. Later inspection showed an insulation defect in the proximal part of the removed lead and signs of arcing on the defibrillator. We postulated that a short circuit at the time of a shock had damaged the generator circuitry resulting in a false reading of the
impedance. A pocket haematoma necessitated reoperation in one patient. Laceration of the superior caval vein during a laser procedure resulted in acute pericardial tamponade in another patient. Acute surgery with the use of extracorporal circulation was necessary to repair the defect. The patient recovered with no sequelae. The total average procedure time was 162±72 min. Discussion Until now, extraction of ICD leads has only been reported in a limited number of patients.'-5 Le Franc 119
Endovascular extraction techniques
et al. reported successful endovascular extraction of 13 defibrillation leads using telescoping dilator sheaths in five patients and a femoral approach in six leads.2'6 Vassilikos et al. reported extraction offour shock leads with a locking stylet although in one lead a femoral approach was necessary.4 With a laser sheath, Krishnan et al. described successful extraction of defibrillator leads in ten patients and Kennergren et al. in 15 out of 16 patients.3'5 We extracted all shock leads successfully in 16 patients: in 13 patients with an approach including a laser sheath, and in one patient the lead was further removed during surgery for tamponade complicating laser sheath extraction. There are no comparative studies of conventional extraction techniques vs. laser sheath extraction. In pacemaker patients, the laser performed more predictably during initial extraction attempts than the conventional techniques but the final results did not differ in large registries of both techniques.79 Only Krishnan et al. reported a major complication ofICD lead extraction in a patient during laser sheath extraction.3 They performed lead extraction in the catheterisation room and although the patient was transferred to the operating room for emergency surgery after tamponade, severe neurological damage led to his demise. We encountered one tamponade: as our procedures were carried out in the operating room under general anaesthesia with the patient prepared for thoracotomy, the bleeding could be swiftly controlled and the patient recovered without sequelae. These reports are too limited to judge the real incidence of complications. It has been stated that extensive fibrous tissue growing into the grooves of the defibrillation coils could make extraction of ICD leads more difficult.3 10 Therefore, it is safe to assume that complications will be no less than with pacing leads where major complications occur in between 1.4% and 3.5% of procedures with a mortality of 0% to 0 8% 5,8,9,11
Regarding infection, the same considerations for lead extraction in pacemaker leads apply to ICD patients. Extraction of all hardware has the best chance of curing a device-related infection.'2 In a policy statement, NASPE advocates the removal of all malfunctioning ICD leads when interference poses a threat to the patient, but these conditions are still largely undetermined and not fully evaluated.'3 Mechanical dysftmction of either endocardial shock or pace-sense leads (excluding dislodging, increased thresholds and loose set screws) occurs in between 0 and 3% of ICD patients in papers reporting on more than 150 patients (table 2).14-24 Interestingly, the most commonly mentioned defect in defibrillator leads is malfunction ofthe pacesense conductors. This discrepancy between pace-sense and shock conductor may indicate a true lower complication rate of the shock conductors, or it may reflect the difficulty to detect a defective insulation or 120
conductor of the shock lead. Until recently, the only available test of the shock conductor was shock impedance measured after a spontaneous or test shock. But a typical insulation defect will have high impedance compared with the low impedance of the shock coil. Any aberration may therefore fall within normal serial changes in defibrillation lead impedance and can be missed during routine follow-up.25 An interruption of the high voltage conductor is expected to result in increased impedance. However, normal impedance of the high voltage circuit during a high voltage shock has been reported, only becoming abnormally high when measured at 5 volt with a pacing system analyser or at low energy high voltage test shocks.26'27 A high voltage shock ofsufficient energy is probably able to 'jump' a lead fracture resulting in shock delivery with an apparent normal impedance. This stresses the need for more sensitive and easily applicable methods for measuring high voltage conductor integrity. Mehdirad et al. showed that calculated impedance measurements using delivery of low voltage subthreshold stimuli are highly correlated to impedance measured during shock delivery.28 A similar low voltage test is now incorporated in present ICDs and may allow for a more reliable control of the continuity of the shock conductor than test shocks during lead revision.29 Exceptionally, a generator dysfunction can be responsible for changes in the measured shock lead impedance. One of our patients presented with an abnormally low shock impedance. When a new ICD lead was inserted, the same low impedance was measured again and we obtained normal shock impedance only after replacing the generator. An insulation defect close to the generator had resulted in a short circuit damaging the generator circuitry, thus causing a false reading of the impedance. Gummert et al. described a similar situation but with the insulation defect in the proximal part of the sensing lead.30 In both cases, the generator circuitry could not withstand the high load caused by the short circuit current. Malfunctioning or redundant leads can then either be extracted or abandoned, sometimes in a separate pocket.31'32 There is, however, a possibility of interference with both pace-sense function and defibrillation. Direct mechanical contact between endocardial leads may generate spurious electrical potentials resulting in inappropriate shocks or inhibition of pacing.33'34 To avoid contact, a new shock lead may be placed in the right ventricular outflow tract, but this can significantly increase the energy requirements for defibrillation compared with a right ventricular apical position.35'36 True bipolar leads should be less prone to this complication as the sensing electrodes are closely spaced and contact can be more easily avoided. Contact between two leads by adjacent coils or insulation defects may potentially interfere with the defibrillation threshold. The latter was not affected in an animal model, whether or not the active electrode Netherlands Heart Joumal, Volume 9, Number 3, June 2001
Endovascular extraction techniques
touched a passive electrode of an abandoned lead.37 However, these data are restricted to intact, insulated electrodes and a short circuit may occur during a shock if there is an insulation defect or the connector is not properly capped.27 The risk of venous occlusion with multiple leads was not an indication for extraction in our patients. Although there are incidental reports on superior vena cava occlusion, there are no data indicating an excess risk of venous occlusion in the presence of multiple ICD leads.34'38-40 Further, the risk of venous occlusion from lead extraction itself is uncharted. Preoperative phlebography is important to reveal asymptomatic venous obstruction, which occurred in two out of the 18 patients. In this situation we prefer to extract a single non-functional lead and insert new leads through an exchange procedure. This preserves the opposite pectoral site for future use in the event of complications, and prevents bilateral occlusion. Although right-sided pectoral implantation is an alternative, a higher defibrillation threshold has been reported.41-45 Conclusion Although we and other authors have good results from lead extraction in ICD patients, it has only been performed in a limited number of patients and not without complications. In the event of infection, lead extraction remains the therapy ofchoice in patients in whom the risk ofextraction is considered low. Until more data become available on the safety of lead extraction, it appears to be safe to leave malfunctioning leads in ICD patients in situ on the condition that insulation defects are excluded or properly insulated, and with the connector pin adequately capped.31'32 Under these conditions, a separate pace-sense lead can be inserted if damage to the shock conductor is excluded in case ofpace-sense malfunction only. The original lead can then be reused as a shock electrode.'8'46 In all other instances, given the consequences offailed ICD therapy, it is probably safer to extract any damaged or suspected pace-sense or shock lead. -
7 8 9
10 11 12 13
14
15
16
17
18 19
20 21
22
References 1 2
3 4
5 6
Jordaens L, Belleghem Y van, Herregods L. Removal of endocardial defibrillation leads. Pacing Clin Electrophysiol 1996;19:127-9. Le Franc P, Klug D, Jarwe M, et al. Extraction ofendocardial implantable cardioverter-defibrillator leads. Am J Cardiol 1999;84: 187-91. Krishnan SC, Epstein LM. Initial experience with a laser sheath to extract chronic transvenous implantable cardioverter-defibrillator leads. AmJ Cardiol 1998;82:1293-5. Vassilikos VP, Maounis TN, Chiladakis J, Cokkinos DV, Manolis AS. Percutaneous extraction oftransvenous defibrillator leads using the VascoExtor pacing lead removal system. J Interv Card Electrophysiol 1999;3:247-51. Kennergren C. Excimer laser assisted extraction of permanent pacemaker and ICD leads: present experiences of a European multicentre study. EurJ Cardiothorac Surg 1999;15:856-60. Le Franc P, Klug D, Jarwe M, et al. Extraction and reimplantation of defibrillation leads through a thrombotic subclavian vein.
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Pacing Clin Electrophysiol 1999;22:977-8. WikoffBL, Byrd CL, Love CJ, et al. Pacemaker lead extraction with the laser sheath: results of the pacing lead extraction with the excimer sheath (PLEXES) trial. JAm Coll Cardiol 1999;33:1671-6. Smith HJ, Fearnot NE, Byrd CL, WilkoffBL, Love CJ, Sellers TD. Five-years experience with intravascular lead extraction. U.S. Lead Extraction Database. Pacing Clin Electrophysiol 1994;17:2016-20. Byrd CL, WikoffBL, Love CJ, et al. Intravascular extraction of problematic or infected permanent pacemaker leads: 1994-1996. U.S. Extraction Database, MED Institute. Pacing Clin Electrophysiol 1999;22:1348-57. EpsteinAE, Kay GN, Plumb VJ, DaileySM,Anderson PG. Gross and microscopic pathological changes associated with nonthoracotomy implantable defibrillator leads. Circulation 1998;98:1517-24. Reiser C, Byrd CL, WikoffBL, et al. Pacing Lead Extraction With the Excimer Sheath Trial: Final Report [abstract]. Pacing Clin Ekctrophysiol 1998;22:708. Bracke FA, MeijerA, Gelder B van. Pacemaker lead complications: when is extraction appropriate and what can we learn from published data? Heart 2001;85:254-9. Love CJ, WilkoffBL, Byrd CL, et al. Recommendations for extraction of chronically implanted transvenous pacing and defibrillator leads: indications, facilities, training. North American Society of Pacing and Electrophysiology Lead Extraction Conference Faculty. Pacing Clin Electrophysiol 2000;23:544-51. Stambler BS, Wood MA, Damiano RJ, Greenway PS, Smutka ML, Ellenbogen KA. Sensing/pacing lead complications with a newer generation implantable cardioverter-defibrillator: worldwide experience from the Guardian ATP 4210 clinical trial. JAm Coll Cardiol 1994;23:123-32. Schwartzman D, Nallamothu N, Callans DJ, Preminger MW, Gottieb CD, Marchlinski FE. Postoperative lead-related complications in patients with nonthoracotomy defibrillation lead systems. JAm Coll Cardiol 1995;26:776-86. Fahy GJ, Kleman JM, WIkoffBL, Morant VA, Pinski SL. Low incidence of lead related complications associated with nonthoracotomy implantable cardioverter defibrillator systems. Pacing Clin Electrophysiol 1995;18:172-8. Jones GK, Bardy GH, Kudenchuk PJ, et al. Mechanical complications after implantation of multiple-lead nonthoracotomy defibrillator systems: implications for management and future system design. Am HeartJ 1995;130:327-33. Lawton JS, Ellenbogen KA, Wood MA, et al. Sensing lead-related complications in patients with transvenous implantable cardioverter-defibrillators. Am J Cardiol 1996;78:647-51. Gupta A, Zegel HG, Dravid VS, Nierenberg SJ, Freiman DB. Value of radiography in diagnosing complications of cardioverter defibrillators implanted without thoracotomy in 437 patients. Am JRoentgenol 1997;168:105-8. Bardy GH, Yee R, Jung W. Multicenter experience with a pectoral unipolar implantable cardioverter-defibrillator. Active Can Investigators. JAm Coll Cardiol 1996;28:400-10. Gold MR, Peters RW, Johnson JW, Shorofsky SR Complications associated with pectoral implantation of cardioverter defibrillators. World-Wide Jewel Investigators. Pacing Clin Electrophysiol 1997; 20:208-11. Tyers GF, Sanders R, Jacqmein W. Reliability of coated wire defibrillation leads. Pacing Clin Electrophysiol 1999;22:174-8. Gallik DM, Ben Zur UM, Gross JN, Furman S. Lead fracture in cephalic versus subclavian approach with transvenous implantable cardioverter defibrillator systems. Pacing Clin Electrophysiol 1996; 19:1089-94. Drucker EA, Brooks R, Garan H, et al. Malfunction of implantable cardioverter defibrillators placed by a nonthoracotomy approach: frequency of malfunction and value ofchest radiography in determining cause. AmJRoentgenol 1995;165:275-9. Schwartzman D, Hull ML, Callans DJ, Gottlieb CD, Marchlinski FE. Serial defibrillation lead impedance in patients with epicardial and nonthoracotomy lead systems. J Cardiovasc Electrophysiol 1996;7:697-703. Epstein AE, Shepard RB. Failure of one conductor in a nonthoracotomy implantable defibrillator lead causing inappropriate sensing and potentially ineffective shock delivery. Pacing Clin Electrophysiol 1993;16:796-800. Haddad L, Padula LE, Moreau M, Schoenfeld MH. Troubleshooting implantable cardioverter defibrillator system malfunc-
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Endovascular extraction techniques
28
29
30 31
32
33
34
35
36
37
tions: the role of impedance mcasurements. Pacing Clin Electrophysiol 1994;17:1456-61. Mehdirad AA, Stohr EC, Love CJ, Nelson SD, Schaal SF. Implantable defibrillators impedance measurement using pacing pulses versus shock delivery with intact and modified high voltage lead system. Pacing Clin Electrophysiol 1999;22:437-41. Stevens J, Buchwald AB, Krieglstein H, Unterberg C. Early detection of lead fracture by painless high voltage lead impedance measurement in a transvenous ICD lead system. JInterv Card Electrophvsiol 2000;4:269-72. Gummert J, Krauss B, Hutschenreiter W, Hambrecht R, Mohr FW. Sensing lead insulation defect resulting in a damage of the ICD pulse generator case. Pacing Clin Electrophysiol 1998;21:478-9. Mehta D, Nayak HM, Singson M, et al. Late complications in patients with pectoral defibrillator implants with transvenous defibrillator lcad systems: high incidence of insulation breakdown. Pacing Clin Electrophysiol 1998;21:1893-900. Daoud EG, Man KC, Morady F, Strickberger SA. Rise in chronic defibrillation energy requirements necessitating implantable defibrillator lead system revision. Pacing Clin Electrophvsiol 1997;20: 714-9. Pfitzner P, Trappe HJ. Oversensing in a cardioverter defibrillator system caused by interaction between two endocardial defibrillation leads in the right ventricle. Pacing Clin Electrophvsiol 1998; 21:764-8. Nunain SO, Roelke M, Trouton T, et al. Limitations and late complications of third-generation automatic cardioverter-defibrillators. Circulation 1995;91:2204-13. Tang AS, Hendry P, Goldstein W, Green MS, Luce M. Nonthoracotomy implantation of cardioverter defibrillators: preliminary experience with a defibrillation lead placed at the right ventricular outflow tract. Pacing Clin Electrophysiol 1996;19:960-4. Winter J, Heil JE, Schumann C, et al. Effect of implantable cardioverter/defibrillator lead placement in the right ventricle on defibrillation energy requirements. A combined experimental and clinical study. EurJ Cardiothorac Surg 1998;14:419-25. Fotuhi PC, KenKnight BH, Melnick SB, Smith WM, Baumann
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45
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GF, Ideker RE. Effect of a passive endocardial electrode on defibrillation efficacy of a nonthoracotomy lead system. JAm Coll Cardiol 1997;29:825-30. Minen G, Proclemer A, Facchin D. Asymptomatic supcrior vena caval occlusion: a complication of nonthoracotomy implantation of cardioverter defibrillator. Pacing Clin Electrophysiol 1998;21: 1676-8. Dhondt E, Hutse W, Vanmeerhaeghe X, Jordaens L. Superior vena cava syndrome after implantation of a transvenous cardioverter defibrillator. Eur HeartJ 1995;16:716-8. Pacifico A, Wheelan KR, Nasir N Jr, et al. Long-term follow-up ofcardioverter-defibrillator implanted under conscious sedation in prepectoral subfascial position. Circulation 1997;95:946-50. Jensen SM, Pietersen A, Chen X. Implantation of active can implantable defibrillators in the right pectoral region. Pacing Clin Electrophysiol 1998;21:476-7. Natale A, Sra J, Geiger MJ, Newby K, Akhtar M, Pacifico A. Right side implant of the unipolar single lead defibrillation system. Pacing Clin Electrophysiol 1997;20:1910-2. Schofield IJ, Rankin I, Bennett DH. Right sided pectoral implantation of an 'active can' transvenous implantable cardioverter-defibrillator with single right ventricular lead. Br Heart J 1995;74:204. Epstein AE, Kay GN, Plumb VJ, Voshage-Stahl L, Hull ML. Elevated defibrillation threshold when right-sided venous access is used for nonthoracotomy implantable defibrillator lead implantation. The Endotak Investigators. JCardiovascElcctrophysiol 1995; 6:979-86. Friedman PA, Rasmussen MJ, Grice S, Trusty J, Glikson M, Stanton MS. Defibrillation thresholds are increased by right-sided implantation of totally transvenous implantable cardioverter defibrillators. Pacing Clin Electrophysiol 1999;22:1186-92. Lawton JS, Wood MA, Gilligan DM, Stambler BS, Damiano RJ Jr, Ellenbogen KA. Implantable transvenous cardioverter defibrillator leads: the dark side [editorial]. Pacing Clin Electrophysiol 1996;19:1273-8.
Netherlands Heart Joumal, Volume 9, Number 3, June 2001
