Epicardial and Nonthoracotomy Defibrillation Lead Systems Combined with a Cardioverter Defibrillator

The intraoperative and long-term results were reviewed in 67 patients who underwent implantation of the Ventritex Cadence defibrillator with either epicardial patch (EPI, 25 patients) or nonthoracotomy CPI Endotak (ENDO, 42 patients) defibrillation lead systems. In the ENDO group, 35 patients (83 %) had a defibrillation threshold (DFT) of ≤ 20 joules and did not require a subcutaneous patch. Intraoperatively, the DFT was 13 ± 9 joules (mean ± SD) for EPI and 15 ± 8 joules for ENDO (P = NS). There was no perioperative death in either group. During a mean follow-up of 12 ± 8 months, there was no sudden death, and four patients died from congestive heart failure (3 EPI, 1 ENDO). During follow-up, 875 spontaneous arrhythmia episodes (AE) occurred in 15 of 25 EPI patients (60%). versus 652 in 28 of 42 ENDO patients (67%; P = NS). Ventricular tachycardia at a rate ≥ 222 beats/min or ventricular fibrillation represented 167 AE for EPI (19%) and 182 AE for ENDO (28%), and was terminated by the first shock in 76% and 75% of attempts, respectively. Ventricular tachycardia at a rate ≥ 222 beats/min represented a total of 1,178 AE and antitachycardia pacing was successful in 660 of 708 AE (93%) with EPI and 414 of 470 AE (88%) with ENDO lead systems (P= NS). Therefore, a nonthoracotomy approach using the Cadence V-100 is safe and effective and has clinical results that are not significantly different from epicardial defibrillation lead systems.     

A Prospective, Randomized Evaluation of a Nonthoracotomy Implantable Cardioverter Defibrillator Lead System

Nonthoracotomy lead systems for ICDs have been developed that obviate the need for a thoracotomy and reduce the morbidity and mortality associated with implantation. However, an adequate DFT cannot be achieved in some patients using transvenous electrodes alone. Thus, a new subcutaneous "array" electrode was designed and tested in a prospective, randomized trial that compared the DFT obtained using monophasic shock waveforms with a single transvenous lead alone that has two defibrillating electrodes, the transvenous lead linked to a subcutaneous/submuscular patch electrode, and the transvenous lead linked to the investigational array electrode. There were 267 patients randomized to one of the three nonthoracotomy ICD lead systems. All had DFTs that met the implantation criterion of ≤ 25 J. The resultant study population was 82% male and 18% female, mean age of 63 ± 11 years. The indication for ICD implantation was monomorphic VT in 70%, VF in 19%, monomorphic VT/VF in 6%, and polymorphic VT in 4% of the patients, respectively. The mean LVEF was 0.33 ± 0.13. The mean DFT obtained with the transvenous lead alone was 17.5 ± 4.9 J as compared to 16.9 ± 5.5 J with the lead linked to a patch electrode (P = NS), and 14.9 ± 5.6 with the lead linked to the array electrode (array versus lead alone, P = 0.0001; array versus lead/patch, P = 0.007). The results of this investigation suggest that the subcutaneous array may be superior to the standard patch as a subcutaneous electrode to lower the DFT and increase the margin of safety for successful nonthoracotomy defibrillation.     

Safety of Pacemaker Implantation in Patients with Transvenous (Nonthoracotomy) Implantable Cardioverter Defibrillators

While several reports bave documented the safety of implantation of transvenous pacemakers in patients with epicardial patch-based impiantable cardioverter defibrillators (ICDs), the implantation of transvenous pacemakers in patients with transvenous (nonthoracotomy) ICDs has not been well-descrihed. We present three patients with transvenous ICDs who subsequently underwent implantation of transvenous pacemakers without complication. Technical considerations and a testing protocol for detection of pacemaker-ICD interactions are discussed.     

Predictors of Fracture Risk of a Small Caliber Implantable Cardioverter Defibrillator Lead

Introduction: The Sprint Fidelis 6949 implantable cardioverter defibrillator (ICD; Medtronic Inc., Minneapolis, MN, USA) lead has a high rate of fracture. Identification of predictors of subsequent fracture is useful in decision making about lead replacement and for future lead design. We sought to determine if there are clinical, procedural, or radiological features associated with a greater risk of subsequent lead fracture. Methods: Patients with Sprint Fidelis 6949 lead fractures (Fracture group) were identified from our institutional database. Each patient in the Fracture group was matched to two controls, immediately preceeding and succeeding Sprint Fidelis 6949 implant. Clinical and procedural characteristics were compared. Chest radiographs performed 2 weeks after ICD implant were reviewed by an observer blinded to outcomes. The following features were assessed: ICD tip location, lead slack, kinking of the lead body (≥90°), and presence of lead “crimping” within the anchoring sleeve. Results: Twenty‐six patients with Sprint Fidelis 6949 lead fractures were identified and were matched to 52 control patients. On univariate analysis, a higher left ventricular ejection fraction (LVEF), prior ipsilateral device implant, history of prior ICD lead fracture, and noncephalic venous access were associated with risk of lead fracture. On multivariate analysis, a higher LVEF was the only independent predictor of lead fracture (P = 0.006). Radiological features were similar between the two groups. Conclusions: In this study, a higher LVEF was associated with a greater risk of lead fracture in patients with Sprint Fidelis 6949 ICD leads. Radiographic features did not predict subsequent risk of lead fracture in our population. (PACE 2010; 437–443)     

Failure of Defibrillator Paddle as Mimic for Subcutaneous Patch Lead During Nonthoracotomy Implantable Cardioverter Defibrillator Lead Configuration Assessment

It is a common, although virtually unsubstantiated, practice to assess the efficacy of nonthoracotomy lead systems for implantable cardioverter defibrillators using a defibrillator paddle as mimic for the subcutaneous patch lead. We report a case in which an adequate defibrillation threshold was documented with the nonthoracotomy lead system using a defibrillator paddle but not following implantation of the true subcutaneous patch lead. This case suggests that the substitution of a defibrillator paddle for the subcutaneous patch lead during nonthoracotomy lead system evaluation may have significant limitations in assessing lead configuration efficacy.     

Initial Experience with Transvenous Implantable Cardioverter Defibrillator Lead Systems: Operative Morbidity and Mortality

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

Total Pectoral Implantation: A New Technique for Implantation of Transvenous Defibrillator Lead Systems and Implantable Cardioverter Defibrillator

We describe a new approach to tolal pectoral implantation of cardioverter defibrillators with an endocardial defibrillation lead system. Endocardial lead configuration used was an FDA approved right atrial-superior vena cavo defibriliation spring electrode, right ventricular bipolar sensing electrode, and a pectoral patch. Endocardial leads were implanted via a cephalic or an axillary venesection. Pectoral patch was placed in a sabmuscular position. In case of failure to obtain satisfactory thresholds, a small intercostal thoracofomy was performed via fhe same skin incision and patch placed over the epicardium instead of submuscular position and used with Ihe right atrial spring electrode. The device was implanted in the pectoral region, submuscularly, over the patch. Sixteen consecutive patients underwent this approach. With a submascular patch, adequate defibrillation thresholds (< 15 joules [J]) were obtained in 14 (87.5%) patients. In the other two, defibrillation thresholds of ≤ 15) were obtained with a epicardial patch. Pectoral implantation of the device was feasible in all 16 patients and none needed repositioning. Average postimplant hospital stay was 5 days. During follow-up period (average 5 months), none of the patients reported any major local symptoms and no problems have been encountered in device interrogation. Thus, total pectoral implantation of the cardioverter defibrillator including the patch, leads, and the device is feasible. Furthermore, in case of foilure to obtain adequate defibrillotjon thresholds with submuscular patch, an epicardial patch can easily be implanted and allows 100% successful defibrillation at energy levels of ≤ 15 J with right atrial patch configuration.     

Undersensing of Ventricular Fibrillation in a Noncommitted Nonthoracotomy Cardioverter Defibrillator System

Objective: Evaluation of the impact of undersensing on VF detection time and the relationship of undersensing to the programmed shock energy. Background: Failure to reconfirm an ongoing arrhythmia due to undersensing by a noncommitted ICD might prolong the time to therapy. Methods: We measured initial detection times and redetection times at predischarge and at 2 and 6 months in 29 patients (22 men, mean age 60 years) with a noncommitted nonthoracotomy ICD. Telemetry data and output markers were used to analyze each induction. Results: Undersensing hading to failure to reconfirm was present in 44 (11.1%) of 398 episodes of sustained VF and prolonged significantly the median initial detection time from 2.3 seconds (25th and 75th percentiles: 2 and 2.6 s, respectively) to 5.45 seconds (4.3 and 7.35 s. P < 0.0001). One episode required external defibrillation after reconfirmation failure occurred during charging; the total detection time prior to shock was 46 seconds. In a subset of 87 episodes with failed first shocks, the initial detection time was 2.3 seconds (2.1 and 2.8 s) and the redetection time 3 seconds (2.5 and 4.77 s. P < 0.0001). The presence of undersensing prolonged the redetection from 2.6 seconds (2.35 and 3.1 s) to 5.4 seconds (4.53 and 7.35 s, P < 0.0001). Undersensing was more prevalent during the redetection period (P = 0.004) and in episodes of sustained VF in which the first shock energy was higher than 15 f (19.7% vs 5.8%, P < 0.0001). Conclusions: In this automatic defibriliator system, undersensing occurs in 11% of the sustained VF inductions and prolongs detection time significantly. Redetection is longer than initial detection mostly due to the presence of undersensing, the frequency of which is proportional to the programmed energy. The clinical significance of this finding is unknown.     

Low Incidence of Lead Related Complications Associated with Nonthoracotomy Implantable Cardioverter Defibrillator Systems

Implantable cardioverter defibrillators (ICDs) are increasingly being implanted without the need for thoracotomy. Long-term lead performance and stability were evaluated in 150 consecutive patients in whom 1 of 3 nonthoracotomy ICD lead systems was implanted over a 3-year period from September 1990. Results: Twelve (8%) patients (7 males, 5 females) experienced 13 lead complications during a follow-up period of 12 ± 10 months. Complications were related to intracardiac leads in 7 (4 dislodgments, 2 fractures, 1 right ventricular perforation) and patch leads in 6 (2 folding, 1 fracture, 1 erosion, and 2 hematomas) cases. Freedom from lead related complications at 1 year was 92% (95% confidence interval, 86%–95%). A significant difference in freedom from lead complications between the two most frequently implanted lead systems was observed (P = 0.02). Complication rates were similar in the initial 75 and the more recent 75 implants (P= 0.5). The median time between lead implant and detection of complications was 37 days (range 3–1,147). Complications were diagnosed before hospital discharge in only two cases. In five patients, complications were asymptomatic and in three of these, reoperation was required due to inadequate defibrillation thresholds. Reoperation was necessary in 9 of 12 patients. Conclusions: Nonthoracotomy ICD lead systems are associated with a low complication rate. Complications may or may not cause symptoms, usually occur after hospital discharge, and require reoperation. Complications are not related to a "learning curve." There is a significant difference in performance between different lead systems.     

Implantable Cardioverter Defibrillator Implanted by Nonthoracotomy Approach: Initial Clinical Experience with the Redesigned Transvenous Lead System

Standard implantation procedure for the implantable Cardioverter defibrillator (ICD) has traditionary required a thoracotomy approach. A newly revised nonthoracotomy defibrillator lead system that uses a single transvenous tripolar endocardial lead alone or in combination with a subcutaneous/submuscular patch lead was introduced into clinical trials in September, 1990. Fourteen patients requiring a Cardioverter defibrillafor for recurrent sustained ventricular tachycardia (eight patients) or aborted sudden cardiac death (six patients) were evaluated for implantation of this lead system. Primary successful lead system implantation was obtained in nine patients. The remaining five patients had unacceptably high defibrillation thresholds (DFTs) for implantation. One of the nine initially successful implants demonstrated unacceptable DFTs and cross-talk inhibition from a permanent pacemaker necessitating removal of the nonthoracotomy lead system and replacement with a conventional lead system via thoracotomy. All remaining primary implanted patients experienced successful conversion of induced ventricular fibrillation prior to hospital discharge. Continued follow-up and greater experience to confirm the durability and efficacy of the nonthoracotomy AICD lead system are needed.     

Follow-up X Rays Play a Key Role in Detecting Implantable Cardioverter Defibrillator Lead Fracture:

MORISHIMA, I., et al .: Follow-up X Rays Play a Key Role in Detecting Implantable Cardioverter Defibrillator Lead Fracture: A Case of Incessant Inappropriate Shocks Due to Lead Fracture. A patient with an implantable cardioverter defibrillator (ICD) received incessant inappropriate shocks due to a lead fracture 3 years after implantation. Routine lead measurements at 3-month intervals had shown no abnormal findings even at the most recent measurement performed 2 months prior to the event. In contrast, serial observation of chest X rays clearly disclosed progressive lead narrowing starting 11 months prior to the event. This case indicates the importance of the routine chest X rays in long-term follow-up of ICDs and sets a precedent for interpreting lead narrowing in such X rays. (PACE 2003; 26[pt. I]:911–913)     

Modified Magnet Test for a Reversed Automatic Implantable Cardioverter Defibrillator

We present the case of a 55-year-old man with atrial septal defect and cardiomyopathy who underwent implantation of an automatic cardioverter defibrillator (AICD) for ventricular tachycardia resulting in collapse. This case demonstrates multiple unusual complications related to AICD, including rotation of the pulse generator unit about its long axis requiring a "left-handed" magnet test to determine the appropriate counts.     

Nonthoracotomy Implantation of Cardioverter Defibrillators: Preliminary Experience with a Defibrillation Lead Placed at the Right Ventricular Outflow Tract

Although morbidity and mortality associated with defibrillator implantation using a nonthoracotomy approach have decreased as compared with a thoracotomy approach, dfifihrillation thresholds have been higher and fewer patients satisfied implan t criteria. It may be possible to improve on the success of nonthoracotomy defibrillator implantation by the placement of a right ventricular (HV) outflow defibrillation lead. Implnntable car-dioverter defibrillator implantation data of 30 consecutive patients with clinical VT or VF were reviewed. Three defibrillation leads were routinely used. When either pacing threshold at the RV apex ivas inadequate (n - 2) or 18-J shocks were not successful in terminating VF in 3 of 4 trials (n = 8). the RV apex lead was positioned to the HV outflow tract attaching to the septum. Defibrillation testing was first performed with the RV apex lead in combination with CS, SVC. and/or subcutaneous leads. Twenty patients satisfied implant criteria with a defibrillation threshold of 13.5 ± 3.6 J. In 7 of the 10 patients, whose RV lead was repositioned to the RV outflow tract, this lead in combination with SVC, CS, or subcutaneous leads produced successful defibrillation at < 18 J or in 3 of 4 trials. This approach improved the overall success of nonthoracotomy implantation of defibrillators from 69% to 90%, After a follow-up of 27 ± 6 months, there was no dislodgment of the HV outflow tract defibrillation leads. Conclusions: This article reports the preliminary observation that placement of defibrillation leads to the RV outflow tract in humans was possible and without dislodgment. RV outflow tract offers an alternative for placement of defibrillation leads, which may improve on the success of nonthoracotomy defibrillator implantation.     

AutoCapture with Dual-Coil Leads of Implantable Cardioverter Defibrillator

AutoCapture™ (AC) can confirm ventricular capture with true bipolar single coil leads of implantable cardioverter defibrillators (ICD). The compatibility of AC with a new, true bipolar, dual-coil ICD lead needed to be evaluated. This multicenter study enrolled 46 patients (69 ± 10 years, 37 men) undergoing ICD implantation. All patients received a true bipolar, dual-coil lead. Evoked response (ER) sensitivity and AC threshold tests were performed using a pulse generator with the AC algorithm. Mean capture threshold was 0.85 ± 0.67 V, pacing impedance 612 ± 225 Ω, R wave amplitude 13.85 ± 6.17 mV, and defibrillation threshold 14.4 ± 5.1 J. AC was recommended in 45 patients (97.8%) with ER and polarization values of 14.86 ± 7.32 mV and 0.87 ± 0.69 mV, respectively. The AC algorithm was highly compatible with true bipolar, dual-coil ICD leads. An AC algorithm specifically designed for an ICD may improve the generator longevity. Further examination of AC compatibility with other leads is warranted.     

Setting of Relatively Low Energy Outputs May Permit Implantation of a Nonthoracotomy Automatic Cardioverter Defibrillator System When High Energy Outputs Prove Ineffective

At intraoperative testing of defibrillation thresholds during implantation of internal Cardioverter defibrillators, standard step-down approaches of energy outputs are used. If relatively high energy outputs are not successful at defibrillating the heart, the electrodes are frequently reconfigured. When attempting implantation of a nonthoracotomy lead system, high defibrillation thresholds may warrant opening of the chest cavity to place one or more epicardial electrodes. A case is presented where a nonthoracotomy system was able to be implanted using relatively low energy outputs which were reproducibly successful at terminating ventricular fibrillation when higher energy outputs were unsuccessful. Mechanisms for this phenomenon and alternate recommendations for defibrillation testing are presented.     

Lead Fracture in Cephalic Versus Subclavian Approach with Transvenous Implantable Cardioverter Defibrillator Systems

Lead fracture, occurring in approximately 1%–4% of patients, is an infrequent, but potentially catastrophic complication of permanent pacing systems. Its incidence in transvenous defibrillator systems has not been established. We analyzed data from 757 patients undergoing implantation of transvenous Cardioverter defibrillator systems using the Medtronic Transvene Lead® system between October 20, 1989 and June 25, 1992 to determine if site of venous approach influenced incidence of lead fracture. All patients received a 3-lead system in 1 of 3 configurations: (1) right ventricle/superior vena cava/subcutaneous patch; (2) right ventricle/coronary sinus/subcutaneous patch; or (3) right ventricle/superior vena cava/coronary sinus. Of 767 right ventricular leads placed, 523 were placed via the subclavian vein, 221 via cephalic vein, and 18 via the internal jugular (5 leads were implanted using another vein). The total number of leads is greater than the total number of patients, as five patients received a second defibrillator system if the initial system was explanted and reimplanted for any reason. Seven patients (0.9%) had right ventricular lead fracture, presenting with inappropriate defibrillator shocks (1), loss of pacing ability (3), both loss of pacing ability and inappropriate shocks (1), or increased pacing threshold (2). All patients required reoperation. AH had leads placed by the subclavian venous approach, with chest X ray confirming fracture at the clavicle-first rib junction in 6 of 7 cases. Using Fisher's Exact test, the difference in lead fracture between subclavian and cephalic vein implant approached statistical significance (P = 0.08). The trend toward increased lead fracture incidence with leads placed via subclavian vein suggests that cephalic vein approach may be preferable to avoid this complication.     

Preliminary Experience with Nonthoracotomy Implantahle Cardioverter Defihrillators in Young Patients

Implantable cardioverter defihrillators represent an important treatment option for patients with life-threatening tachyarrhythinias. However, the requirement for surgical access to the thorax contributes to significant procedural morbidity with ICD implantation. This study was performed to assess an initial experience with a nonthoracotomy approach to ICD lead implantation in young patients. An international survey identified 17 patients, ranging in age from 12–20 years (mean = 16.7 ± 2.4) and weighing from 33–89 kg (mean = 60.6 ± 13.3), who had undergone placement of the Medtronic Transvene^R defibrillator lead system. Implant indications were aborted sudden cardiac death in 15 patients and recurrent ventricular tachycardia or familial sudden death in 2 patients. At a median follow-up of 7.9 months, 9 of 17 patients had received at least one ICD therapy. There have been no deaths. Complications included patch or generator erosion (3 patients), lead dislodgement (1 patient), and ICD system infection requiring explanation (1 patient). The initial experience with nonthoracotomy ICDs in young patients appears promising. This approach may be particularly advantageous for patients who have undergone prior thoracotomy. Prospective clinical trials will be required to establish the applicability of these lead systems to select patient populations.