Late Retesting of System Performance in ICD Patients Without Spontaneous Shocks

One hundred five implantable cardioverter defibrillator (ICD) patients (71 ± 9 years of age, 83% men) without spontaneous ICD discharges for ≥ 12 months were tested to assess high voltage (HV) circuit integrity and the system's ability to recognize and terminate ventricular fibrillation (VF). Indications for ICD implantation were sustained ventricular tachycardia (VT) (35%), cardiac arrest (27%), and inducible VT (38%). Eighty-two percent of the patients had coronary artery disease (CAD), and the mean left ventricular ejection fraction (LVEF) was 36%± 13%. Results: One hundred patients had inducible VF and five did not. Testing led to ICD reprogramming in 50 (49%) patients. Two (1.9%) patients required ICD replacement: (1) a 45-year-old patient with a Ventritex 110 ICD implanted for 13 months interfaced with a CPI 0062 lead implanted for 46 months could not be defibrillated internally (impedance nonmeasurable); (2) an 82-year-old patient with a 23-month-old Medtronic 7219 ICD interfaced with 6936 and 6933 leads whose defibrillation threshold (DFT) had doubled since implantation (24 J from 12 J). Lead fractures were found in both cases (proximal coil of the 0062, and subcutaneously in the 6933). Based on DFT determinations, the first shock output was programmed lower in 37 patients and higher in 10 patients. Shock pulse width was changed in one patient and the ventricular refractory period in another. No programming changes were made in 54 (51%) patients. Conclusions: (1) Late testing of HV circuit integrity in ICD patients without an ICD shock in ≥ 12 months identifies previously unsuspected HV lead fractures; (2) chronic DFT testing resulted in HV output reprogramming in one-half of the patients.     

A Prospective Randomized Trial of Defibrillation Thresholds from the Right Ventricular Outflow Tract and the Right Ventricular Apex

Background: Right ventricular outflow tract (RVOT) pacing has been suggested to improve hemodynamics and to help prevent pacing-induced cardiomyopathy. Pacing from the RVOT is feasible and equivalent in terms of sensing and stimulation threshold. However, physicians have been reluctant to use RVOT pacing because of concerns that defibrillation efficacy might be adversely affected. To date, there have been no randomized-controlled trials published comparing the defibrillation threshold in leads implanted in the RVOT and the right ventricular apex (RVA).
Objective: The purpose of this study was to compare defibrillation thresholds (DFT) in the RVOT and RVA. Ventricular sensing and stimulation thresholds were also compared.
Methods: This prospective, randomized, multicenter study included 87 patients (70 males, age 69 ± 11 years). At implantation, the patient's ventricular implantable cardioverter-defibrillator (ICD) lead position was randomized to either the RVOT or RVA. A four-shock Bayesian up-down method was used to determine the DFT. Patients were followed for 3 months postimplant.
Results: DFTs were not significantly different in leads implanted in the RVOT (median 8.8 J [6.28, 12.9] vs. 7.9 J [6.20, 12.6], P = 0.65). Threshold and impedance measurements were stable in both RVOT and RVA groups from implant to follow-up. All ICD leads remained stable chronically at the 3-month follow-up.
Conclusion: DFTs in leads placed in the RVOT and RVA are comparable. RVOT ICD lead placement is safe and exhibits similar lead stability, threshold, and impedance measurements as the traditional RVA location.     

Combined Third-Generation Implantable Cardioverter Defibrillator with Permanent Unipolar Pacemakers: Preliminary Observations

As implantable Cardioverter defibrillators (ICDs) are strictly contraindicated in the presence of unipolar pacemakers, currently available options in patients having such chronic pacing systems include: abandoning the implanted pacemaker and selecting an ICD with ventricular demand (VVI) pacing; or replacing the chronic (dual chamber) unipolar pacing system with a dedicated bipolar version prior to ICD implantation. In three patients with previously implanted unipolar pacemakers, we challenged the premise that all ICD systems are incompatible by combining with a third-generation transvenous ICD system (Medtronic 7217B PCD® incorporating true bipolar sensing, a self-limiting auto-adjusting sensitivity, and a tolerant VF detection algorithm. The potential for pace-maker-ICD interaction was minimized by separating the tip of the ICDs transvenous right ventricular pace/sense-defihrillation coil lead from that of the chronic pacemaker lead by > 2–3 cm, and by performing “worst case” intraoperative testing. Although ICD double-counting of the dual chamber pacemaker's atrial and ventricular pacing spikes could be provoked at extreme high output settings, it did not occur at clinically appropriate settings. More importantly, continuous high output asynchronous pacing during ventricular fibrillation (VF) did not interfere with ICD detection. During a mean follow-up period of 18 months, one patient has had VF appropriately terminated bv the ICD. In the remaining two patients, proper VF detection and ICD function was reassessed at 3 months and/or at 1 year during noninvasive testing. Conclusion: These preliminary findings demonstrate that this transvenous ICD system's VF sensing and detection features combined with careful implant technique, rigorous “worst case” testing for possible pacemaker-ICD interaction with regular follow-up, may permit implantation of this ICD system in patients with chronic unipolar pacing systems. Further studies are needed to validate the long-term clinical safety of this promising revised approach to a currently contraindicated device combination.     

Innovative techniques for placement of implantable cardioverter-defibrillator leads in patients with limited venous access to the heart

BACKGROUND: Because of venous occlusion, intracardiac shunting, previous surgery, or small size placement of implantable cardioverter-defibrillator (ICD) leads may not be possible using traditional methods. The purpose of this study was to evaluate and describe innovative methods of placing ICD leads. METHODS: The records of all patients undergoing ICD implantation at our institution were reviewed to identify patients with nontraditional lead placement. Indications for ICD, method of lead and coil placement, defibrillation thresholds, complications, and follow-up results were reviewed retrospectively. RESULTS: Eight patients (aged 11 months to 29 years) were identified. Six patients with limited venous access to the heart (four extracardiac Fontan, one bidirectional Glenn, one 8 kg 11-month-old) underwent surgical placement of an ICD coil directly into the pericardial sac. A second bipolar lead was placed on the ventricle for sensing and pacing. Two patients with difficult venous access had a standard transvenous ICD lead inserted directly into the right atrium (transatrial approach) and then positioned into the ventricle. All patients had a defibrillation threshold of <20 J, although one patient required placement of a second coil due to an elevated threshold. There have been no complications and two successful appropriate ICD discharges at follow-up (median 22 months, range 5-42 months). CONCLUSIONS: Many factors may prohibit transvenous ICD lead placement. Nontraditional surgical placement of subcutaneous ICD leads on the pericardium or the use of a transatrial approach can be effective techniques in these patients. These procedures can be performed at low risk to the patient with excellent defibrillation thresholds.     

Preliminary Clinical Results of a Biphasic Waveform and an RV Lead System

Biphasic defibrillation waveforms have provided a reduction in defibrillation thresholds in transvenous ICD systems. Although a variety of biphasic waveforms have been tested, the optimal pulse durations and tilts have yet to be identified. A multicenter clinical study was conducted to evaluate the performance of a new ICD biphasic waveform and new RV active fixation steroid eluting lead system. Fifty-three patients were entered into the study. Mean age was 63 years with a mean ejection fraction of 36.8%. Primary indication for implantation was monomorphic ventricular tachycardia alone (54.7%). Forty-eight patients (90.6%) were implanted with an RV shocking lead and active can alone as the anodal contact. The ICD can was the cathode. In four cases (7.5%), an additional SVC or CS had was used due to a high DFT with the RV lead alone. In an additional case, a chronic SVC lead was used although the RV-Can DFT was acceptable. DFT for all cases at implant was 9.8 ± 3.7 J. Repeat testing at 3 months for a subset of patients showed a reduction in DFT (7.4 ± 3.0 J), P value = 0.03. Sensing and pacing characteristics of the RV lead system remained excellent during the study period (acute 0.047 ± 0.005 ms at 5.4 V and 9.9 ± 6.2 mV R wave; chronic 0.067 ± 0.11 ms at 5.4 V and 9.3 ± 5.4 mV R wave). It is concluded that this lead system provides good acute and chronic sensing and pacing characteristics with good DFT values in combination with this waveform.     

Preliminary results with the simultaneous use of implantable cardioverter defibrillators and permanent biventricular pacemakers: implications for device interaction and development

We report our preliminary experience with the combined use of implantable cardioverter defibrillators (ICD) and biventricular pacemakers in six patients with heart failure and malignant ventricular arrhythmia. Two patients underwent ICD implantation for malignant ventricular arrhythmia after previous biventricular pacemaker implantation. One patient underwent biventricular pacemaker insertion for NYHA Class III heart failure after previous ICD implantation. Two patients underwent single device implantation. In the sixth patient, a combined implantation failed due to an inability to obtain a satisfactory left ventricular pacemaker lead position. The potential for device interaction was explored during implantation. In two patients a potentially serious interaction was discovered. Subsequent alterations in device configuration and programming prevented these interactions with long-term use. No complication of combined device use has been demonstrated during a mean follow-up of 2 months (range 1-4 months). Satisfactory ICD and pacemaker function has also been demonstrated. We conclude that combined device implantation may be feasible with currently available pacing technology and that further prospective studies are required in this area.     

A Comparison of VVIR and DDDR Pacing Following Cardiac Transplantation

We compared the clinical course of patients paced in VVIR versus DDDR mode to determine the most appropriate method of pacing following cardiac transplantation. Pacemaker implantation was required in 9 of 90 orthotopic cardiac transplants (10%). Indications included sinus bradycardia or sinus arrest (8 patients) and AV node dysfunction (1 patient). VVIR pacemakers were implanted in four patients and DDDR in five patients. DDDR patients : The mean P wave was 1.7 mV and the mean atrial stimulation threshold was 0.8 V (at 0.5 msec). During follow-up of 20 months, two atrial lead complications developed (29% of leads in 33% of patients). No lead complications were directly related to endomyocardial biopsy. VVIR patients : All four patients developed VA conduction with mean VA time 180 msec (160–240 msec). Two patients developed pacemaker syndrome. Conclusions : VA conduction and pacemaker syndrome may develop in cardiac transplant recipients paced in the VVIR mode. Dual chamber pacing is technically feasible and preferable following cardiac transplantation.     

Diagnosis and management of inadvertently placed pacing and ICD leads in the left ventricle: a multicenter experience and review of the literature

Three patients from different centers with pacemaker or ICD leads endocardially implanted in the left ventricle are described. All leads, two ventricular pacing leads and one ICD lead, were inserted through a patent foramen ovale or an atrial septum defect. The diagnosis was made 9 months, 14 months, and 16 years, respectively, after implantation. All patients had right bundle branch block configuration during ventricular pacing. Chest X ray was suggestive of a left-sided positioned lead except in the ICD patient. Diagnosis was confirmed with echocardiography in all patients. One patient with a ventricular pacing lead presented with a transient ischemic attack at 1-month postimplantation. During surgical repair of the atrial septum defect 14 months later, the lead was extracted and thrombus was attached to the lead despite therapy with aspirin. The other patients were asymptomatic without anticoagulation (9 months and 16 years after implant). No thrombus was present on the ICD lead at the time of the cardiac transplantation in one patient. We reviewed 27 patients with permanent leads described in the literature. Ten patients experienced thromboembolic complications, including three of ten patients on antiplatelet therapy. The lead was removed in six patients, anticoagulation with warfarin was effective for secondary prevention in the four remaining patients. In the asymptomatic patients, the lead was removed in five patients. In the remaining patients, 1 patient was on warfarin, 2 were on antiplatelet therapy, and in 3 patients the medication was unknown. After malposition was diagnosed, three additional patients were treated with warfarin. In conclusion, if timely removal of a malpositioned lead in the left ventricle is not preformed, lifelong anticoagulation with warfarin can be recommended as the first choice therapy and lead extraction reserved in case of failure or during concomitant surgery.     

Defibrillation Thresholds and Perioperative Mortality Associated with Endocardial and Epicardial Defihrillation Lead Systems

Defibrillation thresholds (DFT) and perioperative mortality were evaluated in 123 patients who had endocardial defibrillation leads implanted in conjunction with the Medtronic model 7216A/7217 (Medtronic, Inc.) cardioverter-defibrillator (ICD). Clinical variables, implant DFTs, and 30-day perioperative mortality were compared with 266 patients who had the ICD implanted with epicardial defibrillation leads. The two groups were comparable in age, gender, and incidence of coronary artery disease. New York Heart Association Class I and II were more frequent in patients with endocardial leads (87.7%) as compared to those with epicardial leads (78.8%; P < 0.001). Mean left ventricular ejection fraction was significantly higher in patients with the endocardial lead system (37% vs 33%; P < 0.05). A significant proportion of patients with epicardial lead systems underwent another cardiac surgical procedure at the time of ICD implantation (13.9%) as compared to none in those who had endocardial leads implanted (P < 0.001). All patients with endocardial leads had implantation of triple lead systems as compared to 53.4% with epicardial leads (P < 0.001). The mean DFT at implant was lower in epicardial lead recipients (8.9 J) as compared to endocardial lead recipients (13.3 J; P < 0.001). Perioperative mortality had a significant trend to lower risk for endocardial lead systems (0.8%) as compared to epicardial systems (4.2%; P = 0.07). We conclude that this endocardial lead system has additional electrode and higher defibrillation energy requirements than the epicardial lead systems used with the Medtronic pacemaker ICD. However, the use of endocardial nonthoracotomy defibrillation leads is associated with a markedly reduced perioperative risk of ICD implantation. This could be due to patient characteristics, a less invasive implant procedure, and absence of concomitant cardiac surgery.     

Initial Experience of Pacing with a Lumenless Lead System in Patients with Congenital Heart Disease

Background: Long-term pacing is frequently necessary in patients with congenital heart disease (CHD). Preservation of ventricular function and avoidance of venous occlusion is important in these patients. Site-selective pacing with a smaller diameter lead is achievable with the model 3830 lead (SelectSecure®, Medtronic Inc., Minneapolis, MN, USA), which was specifically designed to target these complications. We describe our initial experience with the Model 3830 lead in patients with CHD.
Methods: Retrospective analysis of all patients undergoing site-selective implantation of a Model 3830 lead(s) from two congenital heart centers (Bristol, UK, and Dublin, Ireland) from October 2004 until February 2008.
Results: We implanted 139 SelectSecure® leads (atrial n = 70; ventricular n = 69) in 90 patients (57 male) with CHD. Median age at implantation: 13.4 years (1.1–59.2 years), median weight: 43 kg. Sixty-nine patients (76%) were children (<18 years). Indications for lead implantation included atrioventricular block (n = 55), sinus node disease (n = 18), implantable cardiac defibrillator (n = 12), antitachycardia pacing (n = 4), and cardiac resynchronization (n = 1). Twenty-two patients underwent pre-existing lead extraction during the same procedure. All the attempted procedures resulted in successful pacing. One patient had a significantly raised threshold at implantation. There was no procedural mortality. There were two procedural complications. Three patients required lead repositioning for increasing thresholds early postprocedure (<6 weeks). Four leads (2.9%) had displaced on median follow-up of 21.8 months (0.5–42 months).
Conclusions: The Model 3830 lead is safe and effective in patients with CHD. This is a technically challenging patient group yet procedural complication and lead displacement rates are acceptable.     

Retromammary Implantation of an ICD Using a Single Lead System: An Alternative Approach to Pectoral Implantation in Women

Pectoral ICD implantation, although feasible with the release of smaller devices, can be cosmetically disturbing to some patients due to the device protruding under the skin. An ICD was implanted using the retromammary approach in a 25-year-old female patient. Retromammary implantation of an ICD is feasible and offers an alternative approach in women.     

A randomized prospective study of single coil versus dual coil defibrillation in patients with ventricular arrhythmias undergoing implantable cardioverter defibrillator therapy

ICD implantation is standard therapy for malignant ventricular arrhythmias. The advantage of dual and single coil defibrillator leads in the successful conversion of arrhythmias is unclear. This study compared the effectiveness of dual versus single coil defibrillation leads. The study was a prospective, multicenter, randomized study comparing a dual with a single coil defibrillation system as part of an ICD using an active pectoral electrode. Seventy-six patients (64 men, 12 women; age 61 +/- 11 years) were implanted with a dual (group 1, n = 38) or single coil lead system (group 2,n = 38). The patients represented a typical ICD cohort: 60% presented with ischemic cardiomyopathy as their primary cardiac disease, the mean left ventricular ejection fraction was 0.406 +/- 0.158. The primary tachyarrhythmia was monomorphic ventricular tachyarrhythmia in 52.6% patients and ventricular fibrillation in 38.4%. There was no significant difference in terms of P and R wave amplitudes, pacing thresholds, and lead impedance at implantation and follow-up in the two groups. There was similarly no difference in terms of defibrillation thresholds (DFT) at implantation. Patients in group 1 had an average DFT of 10.2 +/- 5.2 J compared to 10.3 +/- 4.1 J in Group 2, P = NS. This study demonstrates no significant advantage of a dual coil lead system over a single coil system in terms of lead values and defibrillation thresholds. This may have important bearing on the choice of lead systems when implanting ICDs.     

Effectiveness of excimer laser-assisted pacing and ICD lead extraction in children and young adults

BACKGROUND: High capture thresholds, decreased electrical sensing, and lead fractures continue to be a problem in children undergoing transvenous pacing. The clinician must therefore decide at the time of pacing system revision to either abandon chronically implanted transvenous pacing leads or extract them. METHODS: We report our experience using an excimer laser-assisted (LA) strategy for removing chronically implanted pacing (36) and implantable cardioverter/defibrillator (ICD) (7) leads in children and young adults. The study population consisted of 25 patients, in whom 29 procedures were performed. The patients ranged in age from 8.4 to 39.9 years, median age was 13.9 years, at the time of the extraction procedure. In all procedures, a Spectranectics locking stylet and excimer laser sheath were used to assist in lead extraction. RESULTS: Lead removal was complete for 39 (91%) leads, and partial for four leads. In two patients, the pacing lead tip was retained and in two, the ring electrode from a bipolar pacing lead was left in situ. All ICD leads were removed completely. Two major complications occurred--cardiac perforation and tamponade (1), and thrombosis of the left subclavian/innominate vein (1). LA extraction facilitated the implantation of new pacing or ICD leads in three patients with obstructed venous access. CONCLUSIONS: Removal of pacing and ICD leads using an excimer LA technique was highly successful. Lead removal was complete in 91%. The most common indication for lead removal in our study was lead fracture. Complications were few, but may be significant.     

Coronary Sinus Shocking Lead As Salvage In Patients with Advanced CHF and High Defibrillation Thresholds

Background: We report a series of three patients whose implantable cardioverter‐defibrillators (ICD) implants were unsuccessful due to inability to achieve defibrillation thresholds (DFT) at maximum available energy after failure of standard modification and enhancement procedures. All patients had advanced cardiomyopathy. Methods: Use of the coronary sinus (CS) for left ventricular (LV) shocking electrode placement resulted in acceptable DFTs in each patient. The position of the shocking coil in all three patients was posterior, and in two patients alongside a left ventricular CS pacing lead. The best shocking configuration tested was LV (CS) + CAN (Anode) to RV (cathode) in each patient. The short‐ and long‐term outcomes of these patients is presented and discussed. Conclusion: This approach is suggested as a salvage option for those problematic patients who have unacceptable DFT results at implantation of an endovascular ICD system. (PACE 2010; 967–972)     

Interactions Between Transvenous Nonthoracotomy Cardioverter Defibrillator Systems and Permanent Transvenous Endocardial Pacemakers

Limited information is available regardIng potential adverse Interactions between transvenous nonthoracotomy cardioverter defibrillators and pacemakers. We describe our experience with 37 patients who have undergone successful Implantation of both a transvenous defibrillator and pacemaker. The patients’mean age was 64 ± 12,9 years. Thirty-three were male and four were female. The mean LVEF wos 30.8%±11.8%, The indications for pacemaker implantation included sick sinus syndrome in 13 patients, complete heart block in 15 patients, sinus brady-cardia secondary to medications In 8 patients, and neurocardlogenlc syncope In 1 patient. The Indications for Insertion of a defibrillator Included medically refractory VT in 27 patients and sudden cardiac death in 10 patients. Twenty-three patients received an Endotak lead and 14 patients received o Transvene lead. Eighteen patients had a pacemaker prior to an ICD, 14 patients had an ICD prior to a pacemaker, and 4 patients had both devices placed simultaneously. Interaction was evaluated at Implant of the second device and 1–3 days after both devices were placed. Detection of VF/VT was analyzed during asynchronous pacing (DOO/VOO) with maximum pacing output. In addition, in six patients, DFT was determined before and after pacemaker implantation. In 14 patients (38%), device interactions that could not always be optimally corrected were observed. In five patients, the pacemaker was reset to the “noise reversion” mode after high energy ICD discharge, Oversensing of atrial pacemaker stimuli resulted in inappropriate ICD firings in four patients. This wos observed only with a specific device ond could not be prevented by atriol leod repositioning in two of them, but required reprogramming of the pacemaker to the VVImode. An increase in DFT was observed in five patients who had a pacemaker implanted after on ICD. Compared with previously published studies, a greater frequency of tronsvenous ICD and pacemaker Interactions were observed. Considering that almost 50% of the patients already have o pacemaker ot the time of ICD Implant, the ovalloblllty of deflbrlllotors with dual chamber pocing capability will not eliminate the potential for this problem.     

The Combined Transvenous Implantation of Cardioverter Defibrillators and Permanent Pacemakers

We developed criteria for implantation and programming of permanent endocardial pacemakers in patients with a nonthoracotomy ICD system. These criteria were prospectively used in 10 patients who recieved an ICD prior to (n = 5) or following (n = 5) implantation of a dual chamber (n = 6) or ventricular (n = 4) pacemaker with a unipolar (n = 4) or bipolar (n = 6) lead configuration. All patients were tested for interactions or malfunctions. Undersensing of ventricular fibrillation by the atrial sense amplifier and inadequate atrial pacing occurred in one patient with a unipolar dual chamber system programmed to AAIR but didn't impair ICD sensing. Transient or permanent loss of capture or sensing of the pacemaker was not observed after ICD shocks with the output programmed to double pulse width and voltage of stimulation threshold and the sensitivity to 50% of the detected R wave. One episode of transient reprogramming occurred without clinical consequences. One unipolar ventricular pacemaker lead had to be exchanged against a bipolar lead because of oversensing of the pacing artifact by the ICD. There was no failure of an ICD to detect ventricular arrhythmias due to inadequate pacemaker activity. During a follow-up period of 21 ± 11 months, a total of 78 ventricular arrhythmias were effectively treated in six patients. Thus, a combined use of transvenous ICD and pacemaker is possible despite the close vicinity of pacing and defibrillations leads. Optimized programming different to the common settings is required. As interactions occurred only in unipolar pacemaker leads bipolar systems should be used in these patients.     

Implantable cardioverter defibrillator in a child using a single subcutaneous array lead and an abdominal active can

This report describes the case of an 8-year-old boy with hypertrophic cardiomyopathy (HCM) who underwent ICD implantation for recurrent syncope. To avoid vascular complications and to minimize the surgical approach in this small child, a nonthoracotomy ICD system was chosen using a single subcutaneous array lead with only one finger, an abdominally placed active can, and epicardial dual chamber pacing and sensing electrodes. During an 8-month follow-up, DFT was confirmed and there were no ventricular tachycardia or complications. It appears to be a safe device for the prevention of sudden cardiac death in infants and small children.     

Thresholds and Complications with Right Ventricular Septal Pacing Compared to Apical Pacing

Background: Right ventricular septal pacing has been proposed as an alternative to apical pacing. However, data concerning thresholds and requirement for lead repositioning with this technique are scant.
Methods: We reviewed data at implantation and follow-up of 362 consecutive recipients of the same model of active fixation lead (Medtronic 5076-58, Minneapolis, MN, USA) to avoid differences due to lead characteristics. Patients were divided into two groups according to whether the lead was positioned on the interventricular septum (n = 157) or at the right ventricular apex (n = 205). Thresholds, lead impedance, and requirement for lead repositioning were compared between groups at implantation and follow-up.
Results: There were no differences between the septal and apical groups in sensing and pacing thresholds or lead impedance, either at implantation or during a 24-month follow-up. In the septal group, the lead had to be repositioned in four patients (2.5%) due to lead dislodgement in two patients, acute threshold rise in one patient, and pericardial effusion in another patient (the lead had unintentionally been positioned on the anterior free wall in these last two patients). In the apical group, the lead had to be repositioned in eight patients (3.9%, P = 0.56) due to lead dislodgement in three patients and acute threshold rise in five patients.
Conclusions: Acute and chronic thresholds associated with septal pacing are similar to those observed with apical pacing, and risk of lead dislodgement is low. However, multiple radioscopic views must be used to avoid inadvertent positioning of the lead on the anterior free wall .     

ICD Implantation via Thoracoscopy without the Need for Sternotomy or Thoracotomy

After development of the technique in mongrel dogs, implantable cardioverter defibrillator (ICD) patch and sensing lead implanlation was attempted via thoracoscopy, without sternotomy or thoracotomy, in three patients. Two large titanium mesh defibrillator patches and two "screw-in" epicardial sensing leads were applied without difficulty in each of two patients. In a third patient, satisfactory placement of the defibrillator patches could not be achieved via thoracoscopy, necessitating thoracotomy. Defibrillation threshold (DFT), cardioversion energy requirement (CER), and rate and morphology signals in those patients with successful thoracoscopic implantation were comparable to those achieved by open technique. We conclude that ICD patch and sensing lead implantation via thoracoscopy is feasible.     

Subpectoral Implantation of ICD Generators: Long-Term Follow-Up

A nonthoracotomy surgical approach using an endocardial electrode and combined implantation of a subcutaneous patch and the implantable cardioverter defibrillator (ICD) generator in a Subpectoral pocket has been described. We report the long-term follow-up results in patients undergoing implantation using this approach. The patient population consisted of 28 patients (22 men and 6 women) with a mean age of 59 ± 12 years. The underlying heart disease consisted of coronary artery disease in 20 patients and dilated cardiomyopathy in 8 patients. Sustained ventricular tachycardia was the mode of presentation in 16 patients and sudden cardiac death in 12 patients. The mean left ventricular ejection fraction was 31%± 6%. The lead system consisted of an 8 French bipolar passive fixation rate sensing lead positioned at the right ventricular apex, an 11 French spring coil electrode positioned at the superior vena cava-right atrial junction (surface area 700 mm²), and submuscular placement of a large patch (surface area 28 cm²) on the anterolateral chest wall near the cardiac apex via a submammary incision. A defibrillation threshold of ≤ 15 joules (J) was required for implantation. This criterion was not satisfied in five patients; thus, a limited thoracotomy was performed via the submammary incision, and the large patch was placed epicardially. The mean R wave amplitude was 12 ± 3 mV, the mean pacing threshold was 1.0 ± 0.5 V at 0.5 msec, and the mean defibrillation threshold was 12.6 ± 3 J. ICD generators implanted were the Ventak-P in 17, PCD-7217 in 5, and the Cadence V-l00 in 6 patients. These patients have been followed for a mean of 14.6 ± 6 months. There was no perioperative mortality, and none of the patients developed an infection during follow-up. Generator migration or significant discomfort requiring ICD repositioning was not observed, although one patient developed an erosion requiring surgical repair.Conclusions: Subpectoral implantation of the ICD generator is feasible and was well tolerated by all patients with an acceptable complication rate (3.5%). As the size of future generation ICDs is reduced, subpectoral implantation may become the preferred approach.