Left atrial appendage volume is an independent predictor of atrial arrhythmia recurrence following cryoballoon pulmonary vein isolation in persistent atrial fibrillation.

Purpose: Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) ablation in persistent AF (persAF), and cryoballoon PVI emerged as an initial ablation strategy. Symptomatic atrial arrhythmia recurrence following successful PVI in persAF is observed more frequently than in paroxysmal AF. Predictors for arrhythmia recurrence following cryoballoon PVI for persAF are not well described, and the role of left atrial appendage (LAA) anatomy is uncertain. Methods: Patients with symptomatic persAF and pre-procedural cardiac computed tomography angiography (CCTA) images undergoing initial second-generation cryoballoon (CBG2) were enrolled. Left atrial (LA), pulmonary vein (PV) and LAA anatomical data were assessed. Clinical outcome and predictors for atrial arrhythmia recurrence were evaluated by univariate and multivariate regression analysis. Results: From May 2012 to September 2016, 488 consecutive persAF patients underwent CBG2-PVI. CCTA with sufficient quality for measurements was available in 196 (60.4%) patients. Mean age was 65.7 ± 9.5 years. Freedom from arrhythmia was 58.2% after a median follow-up of 19 (13; 29) months. No major complications occurred. Independent predictors for arrhythmia recurrence were LAA volume (HR 1.082; 95% CI, 1.032 to 1.134; p = 0.001) and mitral regurgitation ≥ grade 2 (HR, 2.49; 95% CI 1.207 to 5.126; p = 0.013). LA volumes ≥110.35 ml [sensitivity: 0.81, specificity: 0.40, area under the curve (AUC) = 0.62] and LAA volumes ≥9.75 ml (sensitivity: 0.56, specificity 0.70, AUC = 0.64) were associated with recurrence. LAA-morphology, classified as chicken-wing (21.9%), windsock (52.6%), cactus (10.2%) and cauliflower (15.3%), did not predict outcome (log-rank, p = 0.832). Conclusion: LAA volume and mitral regurgitation were independent predictors for arrhythmia recurrence following cryoballoon ablation in persAF. LA volume was less predictive and correlated with LAA volume. LAA morphology did not predict the clinical outcome. To improve outcomes in persAF ablation, further studies should focus on treatment strategies for persAF patients with large LAA and mitral regurgitation.

Safety and efficacy in ablation of premature ventricular contraction: data from the German ablation registry.

BACKGROUND: Patients with frequent premature ventricular contractions (PVCs) are often highly symptomatic with significantly reduced quality-of-life. We evaluated the outcome and success of PVC ablation in patients in the German Ablation Registry. METHODS: The German Ablation Registry is a nationwide prospective multicenter database of patients who underwent an ablation procedure, initiated by the "Stiftung Institut für Herzinfarktforschung" (IHF), Ludwigshafen, Germany. Data were acquired from March 2007 to May 2011. Patients underwent PVC ablation in the enrolling ablation centers. RESULTS: A total of 408 patients (age 53.5 ± 15 years, 55 % female) undergoing ablation for PVCs were included. 32 % of patients showed a co-existing structural heart disease. Acute ablation success of the procedure was 82 % in the overall patient group. In patients without structural heart disease, acute success was significantly higher compared with patients with structural heart disease (86 vs. 74 %, p = 0.002). All patients were discharged alive after a median of 3 days. No patient suffered an acute myocardial infarction, stroke, or major bleeding. After 12 months' follow-up, 99 % of patients were still alive showing a significant different mortality between patients with structural heart disease compared with those without (2.3 vs. 0 %, p = 0.012). In addition, 76 % of patients showed significantly improved symptoms after 12 months of follow-up. CONCLUSION: Based on the data from this registry, ablation of PVCs is a safe and efficient procedure with an excellent outcome and improved symptoms after 12 months.

[Cardiac computed tomography and ablation of atrial fibrillation]. / Kardiales CT und Ablation von Vorhofflimmern.

Both cardiac computed tomography (CT) and interventional electrophysiology (EP) have evolved considerably in recent years. Technical improvements in CT have significantly reduced the radiation dose in cardiac applications. This imaging technology plays an important role in preprocedural planning and guidance of the procedures in many EP centers worldwide. Furthermore, CT is the imaging modality of choice to diagnose relevant complications in ablation of atrial fibrillation, e.g. pulmonary vein stenosis or atrioesophageal fistula. In anatomically driven ablation procedures, such as balloon-based procedures in atrial fibrillation, detailed analysis of the relevant cardiac structures is absolutely crucial not only to reduce radiation exposure and procedure times but also to improve ablation success and to reduce the occurrence of complications. Current software applications enable 3-dimensional reconstruction of cardiac images and the integration into electroanatomical navigation systems. This article reviews the available evidence in this field and highlights recent developments in image guidance for ablation of atrial fibrillation.

Cryoballoon in atrial fibrillation ablation.

Encouraging results of ablation therapy in patients with paroxysmal atrial fibrillation (AF) have prompted changes in professional practice guidelines. The most recent European guidelines have suggested that ablation might be offered as first-line therapy in selected patients. Cryoballoon ablation is a promising technology in interventional AF therapy. Two different sizes of the cryoballoon are currently available: a smaller (23 mm) and a larger (28 mm) balloon relative to the ostial diameter of the pulmonary veins. New tools, the circular mapping catheter and the use of intracardiac echocardiography, provide important periprocedural information. A meta-analysis of previous studies revealed outcome data with an AF-free survival rate of 72.83% at the 1-year follow-up in paroxysmal AF patients undergoing cryoballoon ablation. The most frequent, but reversible complication is phrenic nerve palsy with reported incidences up to 10%. All efforts must be taken to overcome this limitation, since the overall major complication rate tends to be lower in cryoballoon compared to radiofrequency ablation. In persistent AF, reported results in cryoballoon ablation had a limited success rate below 50% after a single procedure. A double balloon approach using both cryoballoon sizes might overcome some of the limitations in persistent AF. Prospective data and randomized studies are required. This article outlines the current status of cryoballoon technology in AF ablation therapy.

Risk factors for recurrence of atrial fibrillation in patients undergoing hybrid therapy for antiarrhythmic drug-induced atrial flutter.

AIMS: Catheter ablation of the inferior vena cava-tricuspid annulus isthmus and continuation of antiarrhythmic drug therapy have been shown to be an effective hybrid therapy for atrial flutter which results from antiarrhythmic drug treatment of atrial fibrillation. The aim of this study was to determine the risk factors for recurrence of atrial fibrillation in patients undergoing hybrid therapy for antiarrhythmic drug-induced atrial flutter. METHODS AND RESULTS: 90 patients with paroxysmal (n=46) or persistent atrial fibrillation (n=44) developed atrial flutter due to the administration of amiodarone (n=48), flecainide (n=22), propafenone (n=14) or sotalol (n=6). Recurrence of atrial fibrillation after ablation was assessed during follow-up on continued antiarrhythmic drug therapy and during long-term follow-up, irrespective of the initial antiarrhythmic medication. During the follow-up on continued antiarrhythmic drug therapy (16+/-13 months), recurrence of atrial fibrillation was documented in 24 of 90 patients (27%). The presence of accompanying pre-ablation episodes of atrial fibrillation on antiarrhythmic treatment (Odds ratio 7.1, 95% confidence interval 2.3 to 25, p=0.001) and decreased left ventricular ejection fraction (Odds ratio 3.7, 95% confidence interval 1.01 to 12.5, p=0.048) were significant and independent predictors of post-ablation atrial fibrillation. Antiarrhythmic medication was discontinued during long-term follow-up due to adverse drug effects (amiodarone, n=12; flecainide, n=1) in 13 patients (14%). During the long-term follow-up, irrespective of the initial antiarrhythmic medication (21+/-15 months), stable sinus rhythm was maintained in 60 of 90 patients (67%). CONCLUSION Hybrid therapy can be considered as the first line therapy for patients with antiarrhythmic drug-induced atrial flutter but patients should be carefully evaluated for accompanying pre-ablation episodes of atrial fibrillation and possible adverse drug effects before initiation of hybrid therapy.

[Surgical and interventional use of radiofrequency current: is there interference with implantable cardioverter/defibrillators?]. / Operativer und interventioneller Einsatz von Radiofrequenzstrom: gibt es Interferenzen mit implantierbaren Cardioverter/Defibrillatoren?

BACKGROUND: During surgical and interventional procedures, interactions between implantable cardioverter defibrillators (ICD) and electrical cautery, respectively, application of radiofrequency (RF) energy may occur. Induction of inadequate shock therapies or device malfunction may result and represent a potential perioperative hazard for the patient. METHODS: Hence, we analyzed the intraoperative interactions in 23 consecutive ICD patients with regard to different surgical and interventional procedures. Sixteen surgical operations (general surgery n = 7, urologic n = 5, abdominal n = 2, gynecological n = 1, thoracic n = 1) and 7 interventional therapies (RF catheter ablation n = 5, endoscopic papillotomy n = 2) were performed. The ICD devices were all located in the left pectoral position and consisted of 15 single and 8 dual chamber defibrillators. During the procedure tachyarrhythmia detection (VF 295 +/- 21 ms, VT 370 +/- 55 ms) of the devices was maintained active (monitoring mode); only ICD therapies were inactivated. The indifferent electrode of the electrical cauter/RF generator was placed in standard positions (right mid femoral position n = 18, thoracic spine area n = 5). After the procedure, the ICD memory was checked for detections, respectively, for changes of the programming. RESULT: There was no misdetection or reprogramming of the ICD caused by electrical cautery or RF energy. CONCLUSIONS: Despite the lack of undesired interactions ICDs should be inactivated preoperatively to assure maximum patient safety. However, should inactivation be ineffective or not manageable, electromagnetic interference is highly unlikely.

Early reinitiation of atrial fibrillation following external electrical cardioversion in amiodarone-treated patients.

UNLABELLED: Early reinitiation of atrial fibrillation (ERAF) following external or internal electrical cardioversion is one of the factors determining unsuccessful electrical cardioversion. Prevention of ERAF has not been studied systematically in patients on amiodarone therapy. METHODS AND RESULTS: 22 patients had ERAF within 1 min after external electrical cardioversion of atrial fibrillation. 11 patients were on amiodarone therapy and 11 patients had no antiarrhythmic medication. The effect of atropine, post-shock atrial pacing and intravenous ajmaline on ERAF was consecutively tested in these patients. Administration of atropine before repeated defibrillation or post-shock atrial pacing prevented ERAF in 9 of the 11 patients (82%) on amiodarone therapy but in only 3 of 11 patients (27%) without amiodarone (p<0.05). In the remaining patients, intravenous ajmaline was effective in the suppression of ERAF in 5 patients without amiodarone and in 1 patient with amiodarone. The PP interval preceding the atrial premature beat reinitiating atrial fibrillation was nonsignificantly longer in amiodarone-treated patients (1127+/-419 ms) in comparison to patients without amiodarone (896+/-271ms). 27% of patients without amiodarone at the time of electrical cardioversion and 55% of patients with amiodarone remained in sinus rhythm during the follow-up of 29+/-14 and 30+/-14 months, respectively. CONCLUSIONS: ERAF in patients on amiodarone can be treated by atropine or atrial pacing to prevent bradycardia-dependent ERAF. ERAF in amiodarone-treated patients does not apparently predict late recurrence of atrial fibrillation on continued amiodarone therapy.

Electroanatomical mapping for visualization of atrial activation in patients with incisional atrial tachycardias.

AIMS: Incisional atrial tachycardias in patients following surgery for congenital heart disease are based on complex structural abnormalities in these hearts. The aim of this study was to evaluate the use of the electroanatomical mapping system, CARTO, in consecutive patients with different forms of incisional atrial tachycardia. METHODS AND RESULTS: The electroanatomical mapping system combines electrophysiological and spatial information and allows visualization of atrial activation in a three-dimensional anatomical reconstruction of the atria. Electroanatomical mapping of right atrial activation was performed in 10 patients after surgery for congenital heart disease, surgery for Wolff-Parkinson-White syndrome, or heart transplantation presenting with 13 incisional atrial tachycardias. The three-dimensional mapping allowed a rapid distinction between focal (n=3) and reentrant mechanisms (n=10) and visualization of the activation wavefronts along anatomical and surgically created barriers. Electroanatomical activation maps (mean right atrial activation time 213+/-107 ms) were constructed with 89+/-60 catheter positions during an average mapping time of 48+/-33 min. Reentrant tachycardias propagating through the tricuspid annulus-vena cava inferior isthmus (n=6) or along periatriotomy loops (n=4) were identified in eight patients. Ectopic atrial foci near surgical scars could be localized in three patients. Catheter ablation by creation of a lesion in a critical isthmus of conduction or by targeting the arrhythmogenic focus eliminated 11 of 13 incisional atrial tachycardias. CONCLUSION: Visualization of atrial activation in a three-dimensional reconstruction of the right atrium using the electroanatomical mapping system CARTO facilitates understanding of the mechanism and defines the reentrant circuits of incisional atrial tachycardias. This new method may improve the success rate of electrophysiologically guided and anatomically guided catheter ablation of incisional atrial tachycardias.

Catheter ablation of atrial flutter due to amiodarone therapy for paroxysmal atrial fibrillation.

AIMS: Antiarrhythmic drug treatment for atrial fibrillation can cause atrial flutter-like arrhythmias. The aim of this study was to clarify the effect of catheter ablation of the tricuspid annulus-vena cava inferior isthmus on amiodarone-induced atrial flutter and to determine the incidence of atrial fibrillation after catheter ablation of amiodarone-induced atrial flutter in comparison to regular typical flutter. METHODS AND RESULTS: Among 92 consecutive patients with typical atrial flutter who underwent isthmus ablation 28 patients had atrial flutter without a history of previous atrial fibrillation (group I), 10 patients had atrial flutter following the initiation of amiodarone therapy for paroxysmal atrial fibrillation (group II) and 54 patients had atrial flutter and atrial fibrillation (group III). Atrial cycle length during atrial flutter in amiodarone-treated patients (group II) (277+/-24 ms) was significantly longer as compared to the cycle length of atrial flutter in group I (247+/-33 ms) and group III patients (235+/-28 ms). The rate of successful transient entrainment and overdrive stimulation to sinus rhythm was not different between patients with (60%) or without amiodarone therapy (group I: 71%, group III: 53%). Successful isthmus ablation with bidirectional conduction block eliminating right atrial flutter was achieved in 90% of amiodarone-treated patients and 93% of patients without amiodarone therapy. In the amiodarone-treated patient group atrial conduction times during pacing in sinus rhythm were significantly prolonged by 20-30% before and after ablation in all regions of the reentrant circuit. During a mean follow-up of 8+/-3 months post-ablation, atrial fibrillation recurred in two of 10 patients on continued amiodarone therapy after successful isthmus ablation. Thus, successful catheter ablation of atrial flutter due to amiodarone therapy was associated with a markedly lower recurrence rate of paroxysmal atrial fibrillation (20%) as compared to patients with atrial flutter plus preexisting paroxysmal atrial fibrillation (76%) and was similar to the outcome of patients with successful atrial flutter ablation without preexisting atrial fibrillation (25%). CONCLUSION: These data suggest that isthmus ablation with bidirectional block and continuation of amiodarone therapy is an effective therapy for the treatment of atrial flutter due to amiodarone therapy for paroxysmal atrial fibrillation.

Amiodarone: maximising survival benefit with empiric or guided therapy.

Review of available data suggests that serial drug testing in patients with a history of sustained ventricular tachyarrhythmias using various antiarrhythmic drugs including amiodarone is able to identify subgroups with favorable and unfavorable outcome (patient groups with suppression vs. no suppression of inducibility of VT/VF). These results more likely reflect patient selection rather than drug effects, thus limiting the role of electrophysiologically guided antiarrhythmic therapy to actively modify outcome. All major and actual antiarrhythmic drug trials including an amiodarone arm, have chosen to deliver this drug empirically in both patients with asymptomatic as well as severely symptomatic life-threatening sustained ventricular tachyarrhythmias instead of a guided approach. The empiric approach is therefore adequate until new valid data comparing the empiric with the guidedor the invasive with the non invasiveapproach tell us otherwise.

[Long-term efficacy of antitachycardia pacing for treatment of ventricular tachycardia in patients with implantable cardioverter/defibrillator]. / Effizienz der antitachykarden Stimulation bei Patienten mit implantierbarem Cardioverter/Defibrillator und monomorphen ventrikulären Tachykardien im Langzeitverlauf - Gibt es Prädiktoren für eine erfolgreiche Uberstimulation?

UNLABELLED: Antitachycardia pacing techniques (ATP) have proved useful for termination of ventricular tachycardia (VT). However, little is known about the efficacy and safety off ATP during long-term follow-up in a larger study population. We analyzed the data of 80 ICD patients (pts) with spontaneous monormorphic VT, mean age 59 +/- 12 years, the mean follow-up was 26 +/- 17 months. 50 pts (62.5%) had coronary artery disease, 18 (22.5%) dilative cardiomyopathy (DCM), the remaining 12 pts (15%) had no or other cardiac diseases. 2926 episodes of ventricular tachycardia (cycle length 349 +/- 51 ms, 240-520 ms) occurred in 64/80 pts (80%), overall efficacy of ATP was 89.9%, acceleration occurred in 4.1% of VTs. Success of ATP did not correlate with positive ATP testing on induced arrhythmias, LVEF, NYHA class or aneurysm. Neither underlying heart disease nor antiarrhythmic medication had an impact on the ATP success rate. ATP efficacy was linked significantly to short VT cycle length (VTCL, 240-300 ms, p < 0.01) and long coupling intervals (91-97%), p < 0. 01). Acceleration occurred in 32% of pts and in 4.1% of VT episodes; it was also dependent on short VT cycle length (< 300 ms vs > 300 ms, p < 0.04) and short coupling intervals (< 81% vs >/= 81%, p

Slow pathway ablation in a patient with common AV nodal reentrant tachycardia and complete situs inversus.

A 72-year-old woman with complete situs inversus underwent successful slow pathway ablation of typical AV nodal reentrant tachycardia. Catheter ablation of AV nodal reentrant tachycardia in dextrocardia required a lengthy procedure but was safe and without complications.

Functional changes of ventricular late potentials by provocation with increase of heart rate. Evaluation during atrial pacing.

BACKGROUND: Standard methods fail to reveal late potentials in 20 to 30% of patients with ventricular arrhythmias after myocardial infarction. However, these patients may develop transient delayed ventricular activation during increases in heart rate. METHODS AND RESULTS: Atrial pacing was performed, at the rates of 100 min-1 and 120 min-1, in 50 patients after myocardial infarction. Twenty-six patients had a history of documented, sustained ventricular tachycardia, 12 had a history of ventricular fibrillation and 12 no history of ventricular arrhythmias. The low-noise surface electrocardiogram was analysed before and during atrial pacing in the time and frequency domains. Fifteen of 26 patients with ventricular tachycardia, four of 12 with ventricular fibrillation and three of 12 without ventricular arrhythmias experienced late potentials during sinus rhythm. Atrial pacing led to a shift of 26 +/- 15 ms of preexistent late potentials into the ST segment, this being greater in patients with anterior infarctions and to an increase in magnitude in patients with inferior infarctions. In patients without late potentials during sinus rhythm, atrial pacing provoked late potentials in eight of 11 patients with ventricular tachycardia, in four of eight patients with ventricular fibrillation and in one of nine patients without ventricular arrhythmias. Low amplitude signals (LAS) were increased in patients after inferior and filtered QRS in patients after anterior infarction. In 10 patients without cardiac disease no late potentials were detectable in the time and frequency domain either at rest or during increased heart rate. CONCLUSIONS: Increase in heart rate may unmask late potentials in patients prone to malignant ventricular arrhythmias. Therefore, functional late potential analysis with non-invasive clinical stress tests, i.e. exercise tests, should be performed only with an adequate rate response. This might identify patients at risk of malignant ventricular arrhythmias otherwise not identified with conventional late potential analysis.

[Analysis of functional changes in ventricular late potentials for risk assessment of ventricular tachycardias after myocardial infarct]. / Analyse funktioneller Veränderungen ventrikulärer Spätpotentiale zur Risikoabschätzung von Kammertachykardien nach Herzinfarkt.

BACKGROUND: Electrophysiological abnormalities during ischaemia and increased heart rate may influence the detection of ventricular late potentials in the surface electrocardiogram. Whether the analysis of functional changes adds information to the risk stratification of patients prone to ventricular tachycardia is unclear. METHODS: We therefore retrospectively investigated 100 selected patients (25 with documented, sustained ventricular tachycardia (< 230/min) ( = VT group), 25 resuscitated from ventricular fibrillation (VF group) and 50 without ventricular arrhythmias (phi VT/VF group)) in the chronic phase after myocardial infarction. Late potential analysis was performed at rest, during atrial pacing at a rate of 100/min and 120/min (n = 60), during and after occlusion of the coronary artery for coronary angioplasty (PTCA) (n = 70), and immediately after maximum exercise using selective signal averaging. RESULTS: At rest in 72% of patients in the VT group, in 32% of the VF group, and in 6% of the phi VT/VF group late potentials could be found. During atrial pacing in 80% of patients in the VT group, in 72% of the VF group, and in 10% of the patients in the phi VT/VF group and during ischaemia because of occluded coronary artery in 86% of patients in and the VT group, 70% of the VF group, and in 20% of the patients of the phi VT/VF group late potentials were present. Immediately after maximum exercise which let both ischaemia and increased heart rate, late potentials were detectable in 92% of patients in the VT group, 80% of the VF group, and in 14% of patients in the phi VT/VF group. Similar results could be achieved by using the Holter-ECG after exact correction of recorder tape speed variations. 62% of patients with only by ischaemia, increased heart rate or exercise provokable late potentials and all patients with preexistent not by PTCA extinguished late potentials developed recurrent ventricular tachycardias during the one year follow-up period. Patients without late potentials (n = 50) and patients with preexistent by PTCA extinguished late potentials (n = 11) had no recurrent ventricular tachycardias. Cycle length of recurrent and clinical tachycardia in patients with preexistent not by PTCA extinguished late potentials (n = 18) were significantly longer than in patients with only provokable late potentials (n = 21). CONCLUSIONS: Analysis of functional changes of ventricular late potentials with exercise or in Holter ECG recordings promises considerable improvement of postinfarction risk stratification especially in patients prone to ventricular fibrillation.

Fast pathway ablation in patients with common atrioventricular nodal reentrant tachycardia and prolonged PR interval during sinus rhythm.

AIMS: This study aimed to clarify the safety and efficacy of selective fast pathway ablation in patients with atrioventricular nodal reentrant tachycardia and a prolonged PR interval during sinus rhythm. Such patients have been reported to have an increased incidence of complete atrioventricular block. METHODS AND RESULTS: In this study, the earliest retrograde atrial activation during atrioventricular nodal reentrant tachycardia and right ventricular stimulation was localized. Fast pathway ablation was then performed in five patients with the common form of atrioventricular nodal reentrant tachycardia and a prolonged PR interval. Three of the five patients had almost incessant atrioventricular nodal reentrant tachycardia. Radiofrequency catheter ablation induced a complete ventriculo-atrial block during right ventricular stimulation in four patients and a marked prolongation of ventriculo-atrial conduction during right ventricular stimulation in one. Non-inducibility of common atrioventricular nodal reentrant tachycardia with and without isoproterenol was achieved in all five patients. The PR interval increased from 254 +/- 53 ms to 276 +/- 48 ms and the atrio-His interval from 172 +/- 46 ms to 192 +/- 45 ms. Second- or third-degree atrioventricular block did not occur during the ablation procedure. During the followup of 19 +/- 20 months none of the patients developed symptoms suggestive of atrioventricular nodal reentrant tachycardia or evidence of second- or third-degree atrioventricular block. CONCLUSION: These data suggest that atrioventricular node (retrograde) fast pathway ablation can apparently be safely performed in patients with common atrioventricular nodal reentrant tachycardia and a prolonged PR interval during sinus rhythm.

Failures of epicardial and transvenous leads for implantable cardioverter defibrillators.

Lead failures constitute a major risk for patients with an implantable cardioverter defibrillator (ICD). However, data about the incidence and patterns of ICD-lead failures in a larger population are lacking. We analyzed the short-term and midterm performance of 27 epicardial and 103 nonthoracotomy ICD-lead systems during a follow-up period of 36 +/- 21 months and 22 +/- 10 months, respectively (p < 0.05). The failure rate was 5 (19%) of 27 in the epicardial and 6 (6%) of 103 in the nonthoracotomy group (p < 0.05). The most common symptom was erroneous detection of ventricular fibrillation from artifact sensing in five patients. Two patients had to be resuscitated because of failure to defibrillate. Loss of pacing and loss of sensing were seen in two patients. Only two asymptomatic lead fractures could be diagnosed on routine radiograph. In conclusion, there was a considerable rate of lead failures, especially in epicardial systems. Long-term studies addressing the longevity of ICD leads, mechanisms of their failures, and improved diagnostic facilities are important to further increase the safety of this therapeutic approach.

The left subclavian vein as an alternative site for implantation of the second defibrillation lead.

The optimal placement for the second defibrillation lead in a two-lead system has never been addressed. We retrospectively reviewed the data of 33 patients with an average age of 59.2 years (range 41-78 years), predominantly male (n = 29), who underwent implantation of a cardioverter defibrillator (ICD) for treatment of ventricular tachycardia (n = 19) or ventricular fibrillation (n = 14). In all patients an attempt was made to implant an endovenous ICD device (leads only, no subcutaneous patch). In group I (n = 18) the defibrillation anode, a separate unipolar lead, was placed in the common position, the superior vena cava. In group II (n = 15) the lead was placed in the left subclavian vein. At least two consecutive shocks reverting ventricular fibrillation at energies < or = 24 J were required for implantation of the ICD device. All shocks were monophasic. The success rate of endovenous defibrillation was significantly higher in group II than in group I (67% vs 28%, P < 0.05). Thus, it could be demonstrated that the position of the defibrillation anode can influence the defibrillation efficacy in transvenous ICD systems. Prospective randomized trials are needed to investigate the optimal position for the second defibrillation electrode, which may gain increasing importance as soon as dual chamber ICDs become available.

Defibrillator implantation in a patient with a persistent left superior vena cava.

The implantation of a transvenous cardioverter defibrillator (PCD 7217B) was performed in a patient with a persistent left superior vena cava. The defibrillation electrodes were positioned in the right ventricle and the superior vena cava via the right subclavian vein. A subcutaneous patch had to be implanted at the left lateral chest wall to achieve sufficient defibrillation thresholds. Three weeks later the system had to be removed because of a generator pocket infection. During the second implantation we placed one electrode in the persistent left superior vena cava perpendicular to the electrode in the right ventricle. Using this configuration transvenous defibrillation was possible without an additional subcutaneous patch.