Arrhythmia recurrences are rare when the site of radiofrequency ablation of the slow pathway is medial or anterior to the coronary sinus os.

AIMS: The site of successful ablation of the slow atrioventricular (AV) nodal pathway may be located in the posteroseptal or midseptal area. We have previously shown that the site of successful radiofrequency (RF) ablation of the slow pathway, rather than residual slow pathway conduction correlates with AV nodal re-entrant tachycardia (AVNRT) recurrences, with more recurrences noted in inferoposterior (to the coronary sinus os) locations. Accordingly, we have since modified our approach, and in a consecutive series of 105 patients we have performed slow pathway RF ablation exclusively at medial or anterior locations, with the objective of prospectively examining the recurrence rate of AVNRT incurred with this approach. METHODS AND RESULTS: The study included 40 men and 65 women, aged 42 +/- 18 years, having RF ablation for symptomatic AVNRT exclusively in anterior to the coronary sinus os locations. A combined anatomical and electrophysiological approach to slow pathway ablation was employed. This series of patients was compared with the previous series of 55 patients (historical group) with AVNRT undergoing RF ablation at both inferoposterior and anteromedial locations. The mean cycle length of the induced AVNRT was 329 +/- 48 ms. RF ablation was successful in all patients (100%). A mean of 7 +/- 6 lesions were applied. Persistent jump or echo beats were noted in 48 patients (46%). The procedure lasted for 2.1 +/- 1.0 h. Fluoroscopy time was 23 +/- 14 min. Procedures were complicated by heart block in two patients (1.9%). Over 26 +/- 19 months, there has been only one recurrence of AVNRT (1%). The historical group had similar age (37 +/- 18 years), gender (17 men/38 women), AVNRT cycle length (340 +/- 60 ms), number of RF lesions (9 +/- 6), or residual slow pathway conduction (42%), but longer fluoroscopy time (41 +/- 25 min) and procedure duration (4 +/- 1 h), and a significantly higher recurrence rate (seven patients/13%) (P=0.004) at a much shorter follow-up period of 12 +/- 8 months. CONCLUSION: AVNRT recurrences are rare (1%) when slow pathway RF ablation is performed in medial or anterior locations at the tricuspid annulus, rather than in inferoposterior sites, whereby a higher (13%) recurrence rate has been previously noted.

Radiofrequency ablation in pediatric and adult patients: comparative results.

BACKGROUND: Radiofrequency (RF) catheter ablation has been widely and successfully employed to cure adult and pediatric patients of a variety of arrhythmias. Only limited data exist which compare the results in these two groups. The aim of this study was to compare the efficacy and safety of RF catheter ablation in pediatric versus adult patients performed by an adult electrophysiology (EP) team. METHODS: The study group included 327 consecutive pediatric (n=47) and adult (n=280) patients, aged 7-82 years (mean 40+/-19), with symptomatic tachyarrhythmias, who underwent RF ablation during the last 6 years. All but ten patients underwent a full EP study during the same session. Procedures were performed in all but five patients with use of local anesthesia and deep or light sedation. The left heart was approached with use of transaortic (n=36) or transseptal (n=55) or both (n=6) techniques. RF ablation was performed for manifest or concealed accessory pathways in 132 patients, AV nodal slow pathway in 119, atrial tachycardia in 24, atrial flutter in 15, atrial fibrillation in one, ventricular tachycardia in 29, and AV node/His bundle in 7 patients. RESULTS: RF ablation was successful in 271 (96.8%) patients in the adult group and in all patients (100%) in the pediatric group, with a mean of 15+/-18 (median: 8) vs 12+/-10 (median: 8) RF applications respectively (P=NS). Complications occurred in four patients (1.4%) in the adult group and in one patient (2.1%) in the pediatric group (P=NS). Fluoroscopy time averaged 43+/-40 min vs 39+/-27 min and procedures lasted for 3.0+/-1.9 hours vs 2.8+/-1.4 hours respectively (P=NS). During long-term follow-up of 25+/-19 months, there were 12 (4.4%) recurrences among the adult patients, and three (6.4%) recurrences in children, with nine of them successfully treated with repeat RF ablation. Procedural variables were dependent on the type of arrhythmia ablated, rather than on patient's age. Patients with multiple accessory pathways or atrial flutter required the greatest number of RF applications and the longest fluoroscopy exposure and duration of the procedure; the lowest values of these variables concerned ablation of the slow AV nodal pathway or the AV node/His bundle. CONCLUSION: RF ablation in adult and pediatric patients performed by an adult EP team is equally efficacious and safe offering cure of symptomatic cardiac tachyarrhythmias in both patient populations.

Autonomic patterns preceding and following accelerated idioventricular rhythm in acute myocardial infarction.

INTRODUCTION: We have investigated the potential relationship between cardiac autonomic activity and accelerated idioventricular rhythm (AIVR) in response to reperfusion in the setting of an acute myocardial infarction (AMI) through spectral analysis of heart rate variability (HRV). METHODS AND RESULTS: We studied 16 patients with AMI who developed spontaneous sustained AIVR after initiation of intravenous thrombolysis. Sympathovagal interactions were evaluated by analysis of the low- (LF) and high-frequency (HF) spectral components of HRV for each 5-min interval over the 30-min periods preceding and following AIVR. The occurrence of AIVR was related to the ST-segment elevation resolution and the angiographic evidence of restored coronary flow to assess timely reperfusion and sustained coronary artery patency. The analysis of spectral components over time revealed combined responses of both autonomic limbs preceding and following AIVR, which were not followed by corresponding changes in heart rate. Ten minutes before AIVR, there was a characteristic continuous increase in LF, in the setting of a concomitant withdrawal of HF, suggestive of a progressive sympathetic predominance. After the end of AIVR, the opposite pattern was found with an increased HF and decreased LF, indicative of parasympathetic rebound overactivity. All patients showed signs of fast reperfusion and complete restoration of coronary flow. CONCLUSION: Our results indicate that reperfusion-induced AIVR is modulated by sympathetic stimulatory effects, whereas a counterregulatory vagal response seems to exert a profound effect upon its suppression. Clinically, the occurrence of early sustained AIVR appears to offer reliable information about both timely reperfusion and sustained and effective coronary artery patency.

Intravenous magnesium sulfate versus diltiazem in paroxysmal atrial fibrillation.

BACKGROUND: Drugs currently available for the acute treatment of paroxysmal atrial fibrillation have significant limitations. We assessed the safety and effectiveness of intravenous magnesium sulfate versus diltiazem therapy in patients with prolonged episodes of paroxysmal atrial fibrillation. METHODS: In a prospective randomized trial, 46 symptomatic patients presenting with paroxysmal atrial fibrillation were given intravenous magnesium sulfate (n=23) or diltiazem (n=23) therapy. Primary outcome measures were effects on ventricular rate control and proportion of patients restored to sinus rhythm at 6 h after initiation of treatment. RESULTS: There were no differences in baseline characteristics between the two groups. Both forms of treatment were well tolerated, with no adverse clinical events. Both drugs had similar efficacy in reducing the ventricular rate at the first hour of treatment (P<0.05) with a tendency toward a further decrease during infusion times of 2 (P<0.01), 3, 4, 5 and 6 h, respectively (P<0.001). However, at the end of the 6-h treatment period, restoration of sinus rhythm was observed in a significantly higher proportion of patients in the magnesium group compared with the diltiazem group [13 of 23 patients, (57%), versus five of 23 patients, (22%), P=0.03]. CONCLUSIONS: Magnesium sulfate favorably affects rate control and seems to promote the conversion of long lasting episodes of paroxysmal atrial fibrillation to sinus rhythm, representing a safe, reliable and cost-effective alternative treatment strategy to diltiazem.

In-vivo testing of digital cellular telephones in patients with implantable cardioverter-defibrillators.

AIMS: To investigate the susceptibility of implantable cardioverter defibrillators to electromagnetic interference generated by digital cellular telephones, functioning in both international transmission technologies: the Global System for Mobile Communication (GSM) and the Digital Cellular System (DCS 1800). METHODS AND RESULTS: In 36 patients with transvenous implantable cardioverter defibrillators from two manufacturers (Medtronic and Guidant/CPI), cellular telephones with different levels of minimal and maximal power output were tested in the transmitting and receiving mode. Evaluation was performed in activated implantable defibrillators during spontaneous cardiac activity and continuous VVI or DDD pacing to assess possible electromagnetic interference. In two patients, appropriateness of ventricular fibrillation detection and therapy was judged during telephone testing. There was no damage, reprogramming, inappropriate shock therapy or pacing inhibition during the tests. In seven pre-pectoral Medtronic implantable defibrillators, transient electromagnetic interference caused 19 erroneous sensing events, when the operating phone was held in close vicinity to the programmer head. These 'pseudo-oversensing' events, which did not result in logging of arrhythmia episodes in the device counter, were interpreted as an adverse interaction between the telephone and the programming device. CONCLUSION: Digital cellular telephones do not represent a risk to Medtronic and Guidant/CPI recipients of the specific implantable defibrillator models herein tested.

Diagnostic superiority of continuous-loop electrocardiographic recording over other testing in a patient with recurrent syncope and underlying coronary artery disease with severe left ventricular dysfunction.

Dysrhythmic causes of syncope may elude diagnosis in postinfarction patients despite elaborate testing, including electrophysiologic study. For a correct diagnosis, capture of cardiac rhythm during patient's typical symptoms is crucial. This report describes a patient with coronary artery disease and decreased left ventricular ejection fraction who experienced recurrent syncopal episodes without obvious precipitating factors. The 12-lead electrocardiogram showed left bundle-branch block indicating a possible conduction abnormality as the underlying cause of syncope. Twenty-four-h Holter monitoring exhibited no sinus rhythm or conduction disturbances but revealed a nonsustained run of ventricular tachycardia. Findings at electrophysiologic testing led to a presumptive diagnosis of tachyarrhythmic cause of syncope; however, the correct diagnosis was only made with use of a loop monitor which documented a 15-s sinus pause during a syncopal episode.

Ancillary tools in pacemaker and defibrillator lead extraction using a novel lead removal system.

A previous report described our preliminary experience with a highly successful pacing lead removal system (VasoExtor). Extending this experience, we found it necessary to use additional tools to enhance the success of percutaneous lead extraction with this system. In the present series, we used the standard locking stylets (S and K), and recently, one newer type of stylet (Magic) over the last 3 years in 34 patients to extract 48 pacemaker leads in 31 patients and 3 defibrillator (ICD) leads in 3 patients. Lead extraction was carried out in 23 men and 11 women (aged 64 +/- 17 years) because of pacemaker infection (n = 21), pacemaker (n = 8) or ICD (n = 3) lead malfunction, or prior to ICD implant (n = 2). Leads were in place for 3.5 +/- 3.7 years. Infections, involving pocket and lead(s), were due to S. epidermidis (n = 13), S. aureus (n = 6), S. aureus plus E. coli (n = 1), for fungi (n = 1). Of the 48 pacing leads, 31 were ventricular, 15 atrial, and 2 were VDD leads. The ICD leads were two double-coil leads (CPI) and one single-coil lead (Telectronics). Using the S (n = 12), K (n = 8), or Magic (n = 3) stylets, all pacing leads in 23 patients and the ICD leads in 2 patients were successfully removed from a subclavian approach using the locking stylets. However, in nine (26.5%) patients ancillary tools were required. In four patients, lead fragments were captured with use of a noose catheter, a pigtail catheter, and a bioptome from a right femoral approach. In two patients, locking could not be effected and a noose catheter from the right femoral vein was used, aided by a pigtail and an Amplatz catheter and a bioptome to remove three leads. In a patient with an ICD lead, a combined subclavian (stylet S) and right femoral approach (noose catheter) was required. In a patient with a dysfunctional ventricular lead 12 years old, a motor drive unit was used to facilitate the exchange of locking stylets, but extraction failed. In another patient, a fragment of a dysfunctional ventricular lead remained intravascularly despite resorting to a femoral approach. Finally, lead removal was completely (32/34, 94%) or partially (1/34, 3%) successful in 33 (97%) of 34 patients for 50 (98%) of 51 leads without complications. In conclusion, to enhance the success of pacing or ICD lead extraction with use of the VascoExtor locking stylets, an array of ancillary tools were required in more than one fourth of patients.

Initial experience with a newer generation coronary stent.

BACKGROUND: Recently, several newer generation stents have become available promising to improve upon the results of coronary angioplasty (PTCA) with its attendant acute and chronic complications. The aim of this study was to prospectively review the results of a preliminary experience with the newer generation R stent in a series of 56 patients. METHODS: This study included 47 men and 9 women, aged 57 +/- 10 years, who presented with stable angina and/or positive exercise testing (n = 12), unstable angina (n = 42), or acute myocardial infarction (n = 2). A consistent approach by a single operator for implantation of the R stent (Orbus Inc., The Netherlands) included stent oversizing (by 0.5 mm) and high pressure (> 12--16 bar) deployment. Dilated vessels comprised the left anterior descending (n = 37) including the diagonal branch in 2 patients, the right coronary artery (n = 17), the left circumflex (n = 13), or a saphenous vein graft (n = 1). The mean left ventricular ejection fraction was 52 +/- 8% and the initial coronary artery stenosis was 85 +/- 8%. Stents were implanted for dissection and/or suboptimal PTCA result or electively. RESULTS: The procedure was successful in all 56 patients (100%). The residual stenosis was < 0--10%. Direct stenting without balloon predilation was performed in 21 patients. Single stents were used in 36 patients and > or = 2 stents in 20 patients. Abciximab (n = 22), eptifibatide (n = 8) or tirofiban (n = 1) was administered in 31 patients (55%). A stent-related complication was noted in one patient (stent misplacement). All patients were discharged alive without infarct or need for surgery. There were no events of subacute stent thrombosis; all patients received combined therapy with aspirin and clopidogrel, the latter for 1 month. In one patient who had received abciximab, severe thrombocytopenia (0 platelet count) was detected at 3 days after discharge but it was fully reversible with no sequelae. Over 5.2 +/- 2.8 (range, 1--11) months, there was one sudden death and two clinical restenoses; no other late complication occurred. CONCLUSION: Initial experience with 73 R stents in 56 patients and a consistent approach by a single operator of stent oversizing and high-pressure deployment resulted in high procedural success (100%), lack of stent thrombosis (0%), and a low stent-related complication rate (1.8%), while the design and profile of the R stent allowed for direct stenting in 37.5% of patients. One should be vigilant for the sporadic occurrence of severe thrombocytopenia with use of IIb/IIIa inhibitors.

Usefulness of reperfusion ventricular arrhythmias in non-invasive prediction of early reperfusion and sustained coronary artery patency in acute myocardial infarction.

BACKGROUND: Established tenets of occurrence of reperfusion ventricular arrhythmias in acute myocardial infarction (AMI) do not provide insight into the timing of achieving reperfusion or whether coronary artery patency is sustained. We assessed the significance of ventricular arrhythmias in the non-invasive prediction of timely reperfusion and sustained restoration of coronary patency after thrombolysis in patients with AMI. METHODS: 24-hour Holter monitors were placed in 163 patients with an AMI before administration of thrombolytic therapy. Patients were classified into 3 groups of early (within 2 hours) or late reperfusion, or no-reperfusion, according with clinical and continuous ST-segment electrocardiographic criteria. Ventricular fibrillation, ventricular tachycardia (VT) and accelerated idioventricular rhythm (AIVR) were also categorized as having occurred early (within the first 2 hours) or late (after the first 2-hour period). Angiographic confirmation of coronary patency was determined 2 to 6 days after AMI. RESULTS: Early reperfusion was predicted by early sustained AIVR in 86% of patients and early non-sustained AIVR in 62.5% of patients, with sensitivity 38% and 77%, and specificity 96% and 69%, respectively; p<0.0001. Late non-sustained AIVR was commonly seen in early and late reperfused patients (92-97%) as well as in non-reperfused patients (74%). Sustained coronary patency was predicted by early sustained AIVR in 93% of patients, as well as by early non-sustained AIVR in 86% of patients and late non-sustained AIVR in 79% of patients, with sensitivity 22%, 55% and 94%, and specificity 95%, 71% and 18%, respectively; p<0.05. CONCLUSION: Only the occurrence of sustained AIVR, and probably early non-sustained AIVR convey useful information about both early reperfusion and sustained coronary artery patency. The absence of AIVR does not preclude successful thrombolysis.

VDD pacing from the middle cardiac vein via a persistent left superior vena cava.

We report a combination of unusual features demonstrating a permanent pacemaker implantation of a single-pass VDD lead by way of an anomalous persistent left superior vena cava in the middle cardiac vein. The ventricular stimulation resembled a right bundle branch block QRS morphology and was successfully synchronized by spontaneous atrial activity. This case illustrates an alternative approach of effective VDD pacing and sensing in patients with such a venous anomaly when other standard implantation sites fail.

Significance of R-on-T phenomenon in early ventricular tachyarrhythmia susceptibility after acute myocardial infarction in the thrombolytic era.

We investigated the clinical significance and mechanism of the R-on-T phenomenon in the current thrombolytic era as potential precipitant of R-on-T-induced early ventricular tachyarrhythmias in patients with a thrombolysed acute myocardial infarction. We also examined the role of QT dispersion on ventricular vulnerability and its association with R-on-T-initiated ventricular tachyarrhythmias. A total of 93 patients underwent 24-hour Holter monitoring starting at hospital admission before thrombolysis. Patients were classified into 2 groups: those with (n = 76) and those without (n = 17) reperfusion according to electrocardiographic criteria. All R-on-T ventricular premature complexes (VPCs) and R-on-T-initiated arrhythmic events (ventricular tachycardia [VT], ventricular fibrillation) were counted to estimate arrhythmia density and severity in 2 time periods during and after completion of thrombolysis. Measurements of QT and QTc intervals and dispersion parameters were obtained on the 12-lead electrocardiogram before thrombolysis and at 24 hours in patients with and without R-on-T VTs. Overall, R-on-T VPCs were rarely observed (1.8% of total VPCs over 24 hours), occurring more frequently during than after thrombolysis (at a rate of 8 vs 0.6 VPCs/hour, p = NS) and at a higher rate during thrombolysis in nonreperfused than in perfused patients (15 vs 8/hour, p = NS). Three VF episodes were observed in 1 reperfused patient, and all were R-on-T initiated. Episodes of nonsustained R-on-T VTs (3.3% of total VTs over 24 hours) appeared more frequent during than after thrombolysis (at a rate of 0.8 vs 0.05 VPCs/ hour, p = NS), and compared with non-R-on-T VTs they were significantly faster (374 +/- 56 ms vs 411 +/- 69 ms; p < 0.05), with a trend toward longer duration. Our findings indicate that R-on-T VPCs and R-on-T VTs are early rare features in acute myocardial infarction, and do not serve as triggers of severe ventricular tachyarrhythmia. The study of ventricular repolarization did not elicit an identifiable risk factor of R-on-T VT susceptibility.

Effects of early captopril therapy after myocardial infarction on the incidence of late potentials.

BACKGROUND: Late potentials (LP) on signal-averaged electrocardiography (SAECG), recorded 6 to 30 days after an acute myocardial infarction (AMI), identify patients at risk for late arrhythmic events. Angiotensin-converting enzyme (ACE) inhibitors have been shown to reduce ventricular remodeling and cardiovascular mortality after AMI. HYPOTHESIS: The aim of this study was to investigate the effect of early (< 24 h) administration of captopril on the presence of LP on Days 6-30 after AMI. METHODS: The study included 117 patients with a first AMI; 63 patients (53 men and 10 women, aged 59 +/- 12 years), 35 with an anterior and 28 with an inferior AMI (44 thrombolyzed), received early captopril therapy. The control group consisted of 54 age-matched patients (39 men and 15 women, aged 60 +/- 12 years), 19 with an anterior and 35 with an inferior AMI (31 thrombolyzed, p = NS), who did not receive early therapy with an ACE inhibitor. The mean left ventricular ejection fraction was similar in both groups (48 vs. 46%). Time domain analysis of SAECG was performed using a band-pass filter of 40-250 Hz. Late potentials were considered present if any two of three criteria were met: (1) Filtered QRS duration (QRSD) > 114 ms, (2) root-mean-square voltage of the last 40 ms of the QRS complex (RMS) < 20 microV, and (3) duration of low amplitude (< 40 microV) signal of the terminal portion of the QRS (LAS) > 38 ms. RESULTS: In the two groups of patients there were no differences in mean values of SAECG parameters. No patient was receiving any antiarrhythmic drugs. In the captopril group LPs were present in 9 of 63 patients (14%) and in the control group in 17 of 54 patients (31%) (p = 0.046). There was no difference in the number of patients with a patent infarct-related artery in the two groups (76 vs. 59%). CONCLUSION: Captopril treatment early after an AMI reduces the incidence of LPs recorded on Days 6-30 and may thus favorably affect the arrhythmogenic substrate.

Electrophysiologist-implanted transvenous cardioverter defibrillators using local versus general anesthesia.

With the advent of smaller biphasic transvenous implantable cardioverter defibrillators (ICDs) and the experience gained over the years, it is now feasible for electrophysiologists to implant them safely in the abdominal or pectoral area without surgical assistance. Throughout the years, general anesthesia has been used as the standard technique of anesthesia for these procedures. However, use of local anesthesia combined with deep sedation only for defibrillation threshold (DFT) testing might further facilitate and simplify these procedures. The purpose of this study was to test the feasibility of using local anesthesia and compare it with the standard technique of general anesthesia, during implantation of transvenous ICDs performed by an electrophysiologist in the electrophysiology laboratory. For over 4 years in the electrophysiology laboratory, we have implanted transvenous ICDs in 90 consecutive patients (84 men and 6 women, aged 58 +/- 15 years). Early on, general anesthesia was used (n = 40, group I), but in recent series (n = 50, group II) local anesthesia was combined with deep sedation for DFT testing. Patients had coronary (n = 58) or valvular (n = 4) disease, cardiomyopathy (n = 25) or no organic disease (n = 3), a mean left ventricular ejection fraction of 35%, and presented with ventricular tachycardia (n = 72) or fibrillation (n = 16), or syncope (n = 2). One-lead ICD systems were used in 74 patients, two-lead systems in 10 patients, and an AVICD in 6 patients. ICDs were implanted in abdominal (n = 17, all in group I) or more recently in pectoral (n = 73) pockets. The DFT averaged 9.7 +/- 3.6 J and 10.2 +/- 3.6 J in the two groups, respectively (P = NS) and there were no differences in pace-sense thresholds. The total procedural duration was shorter (2.1 +/- 0.5 hours) in group II (all pectoral implants) compared with 23 pectoral implants of group I (2.9 +/- 0.5 hours) (P < 0.0001). Biphasic devices were used in all patients and active shell devices in 67 patients; no patient needed a subcutaneous patch. There were six complications (7%), four in group I and two in group II: one pulmonary edema and one respiratory insufficiency that delayed extubation for 3 hours in a patient with prior lung resection, both probably related to general anesthesia, one lead insulation break that required reoperation on day 3, two pocket hematomas, and one pneumothorax. There was one postoperative arrhythmic death at 48 hours in group I. No infections occurred. Patients were discharged at a mean time of 3 days. All devices functioned well at predischarge testing. Thus, it is feasible to use local anesthesia for current ICD implants to expedite the procedure and avoid general anesthesia related cost and possible complications.

Two-coil versus single-coil transvenous cardioverter defibrillator systems: comparative data.

Two types of new-generation transvenous implantable cardioverter defibrillator (ICD) systems, incorporating a two-coil (62 patients, group 1) versus single-coil (32 patients, group 2) lead system were compared among 94 consecutive patients. The two groups were comparable in age (58 +/- 13 vs 59 +/- 14 years), presenting arrhythmia (ventricular tachycardia versus ventricular fibrillation 77%/21% vs 84%/13%), cycle length of induced VT (294 +/- 4 vs 289 +/- 44 ms), number of unsuccessful antiarrhythmic drugs (1.7 +/- 0.8 vs 1.7 +/- 0.7), and left ventricular ejection fraction (35 +/- 12% vs 34 +/- 9%). Both systems were successfully implanted strictly transvenously in all patients. Biphasic shocks were used in all patients. Active shell devices were used in 79% and 84% patients of groups I and II, respectively (P = NS). Intraoperative testing revealed comparable defibrillation threshold (DFT) values (10.2 +/- 3.7 J in group 1 versus 9.3 +/- 3.6 J in group 2 system), and pacing threshold (0.7 +/- 0.3 vs 0.7 +/- 0.3 V), but R wave amplitude and lead impedance were lower in group 1 (13 +/- 5 vs 16 +/- 5 mV, P = 0.003; and 579 +/- 115 vs 657 +/- 111 ohms, P = 0.002, respectively). Lead insulation break requiring reoperation occurred in one patient with an Endotak lead, and two patients with Transvene leads had initially high DFT with a single one-lead/active can system, which was converted to a two- or three-endocardial-lead/inactive can configuration. We conclude that both single-coil and two-coil transvenous ICD systems were associated with high rates of successful strictly transvenous ICD implantation and a low incidence of lead-related complications. Significant differences were noted in the sensed R wave and lead impedance, probably reflecting the active fixation characteristics of the Transvene lead. However, in order to obviate the sporadic need for implantation of additional endocardial leads, as was the case in two patients in this series, a double-coil lead may be preferable.

Percutaneous extraction of transvenous defibrillator leads using the VascoExtor pacing lead removal system.

In the implantable cardioverter defibrillator era the necessity for lead removal is not negligible. A specially designed extraction lead system for percutaneous removal of such leads is lacking, in contrast to the existing pacing lead extraction systems. We report the successful percutaneous extraction of four implantable cardioverter defibrillator leads in three patients because of lead malfunction using a novel pacemaker lead extraction system, the VascoExtor (VascoMed) system. Three leads were successfully removed in two patients using traction with special locking stylets from the superior approach. One lead was removed using the system's additional extraction tools through the femoral approach. There were no complications. This preliminary experience shows that the VascoExtor (VascoMed) pacemaker lead extraction system can also be used in implantable cardioverter defibrillator lead extraction safely and effectively. In addition to the locking stylets, adjunct percutaneous extraction tools may be needed in some cases.

Radiofrequency ablation in older children and adolescents by an adult electrophysiology team.

BACKGROUND: Radiofrequency (RF) catheter ablation has been widely and successfully employed to cure adult patients of a variety of arrhythmias. Only a few centers have a pediatric electrophysiology (EP) service available and have presented similar results in children. The aim of this study was to investigate the efficacy and safety of RF ablation in pediatric patients performed by an adult EP team. PATIENTS AND METHODS: The study group included 33 consecutive pediatric patients, aged 7-18 years (mean 14.1 +/- 3.1), with symptomatic supraventricular tachyarrhythmias, who underwent RF ablation during the last 3 years. All but two patients underwent a full EP study during the same session. Procedures were performed in all but five patients with use of local anesthesia and deep or light sedation. The left heart was approached with use of transaortic (n = 3) or transseptal (n = 7) techniques. RF ablation was performed for manifest (n = 11) or concealed (n = 9) (9 left, 4 anteroseptal, 3 midseptal, and 4 posteroseptal) or right atriofascicular (Mahaim) (n = 1) accessory pathways in 19 patients, 12 slow AV nodal pathways and 2 atrial tachycardia foci in the other 14 patients. RESULTS: RF ablation was successful in all patients (100%) with 1-27 RF applications (mean: 10 +/- 7). There was one complication in a patient with 2 accessory pathways; after RF ablation of a posteroseptal accessory pathway, complete heart block occurred during successful ablation of a second midseptal accessory pathway. Fluoroscopy time averaged 35 +/- 23 min and procedure duration 2.8 +/- 1.4 hours. During long-term follow-up of 19 +/- 10 months, there was one AV nodal tachycardia recurrence at 2.5 months, successfully treated with repeat RF ablation. CONCLUSION: RF ablation in pediatric patients performed by an adult EP team is efficacious and safe offering cure of symptomatic cardiac tachyarrhythmias in this patient population.

Pectoral cardioverter defibrillators: comparison of prepectoral and submuscular implantation techniques.

The purpose of this study was to compare the two techniques of pectoral ICD implantation, prepectoral and submuscular, performed by an electrophysiologist in the catheterization laboratory with use of general or local anesthesia in 45 consecutive patients. Over a period of 30 months, we implanted pectoral transvenous ICDs in 43 men and 2 women, aged 59 +/- 12 years, with use of general (n = 20) or local (n = 25) anesthesia in the catheterization laboratory. Patients had coronary (n = 30) or valvular (n = 4) disease, cardiomyopathy (n = 10) or no organic disease (n = 1), a mean left ventricular ejection fraction of 31%, and presented with ventricular tachycardia (n = 40) or fibrillation (n = 5). One-lead ICD systems (18 Endotak, 10 Transvene/8 Sprint, 2 EnGuard) were used in 38 patients, 2-lead (5 Transvene, 1 EnGuard) systems in 6 patients, and 1 atrioventricular lead ICD system in 1 patient. The prepectoral technique was employed in 29 patients with adequate subcutaneous tissue, while the submuscular technique was used in 16 patients who had a thin layer of subcutaneous tissue. The defibrillation threshold averaged 9-10 J in both groups and there were no differences in pace/sense thresholds. All implants were entirely transvenous with no subcutaneous patch. Biphasic ICD devices were employed in all patients. Active or hot can devices were used in 39 patients. There were no complications, operative deaths, or infections. Patients were discharged at a mean of 3 days. All devices functioned well at predis-charge testing. Over 14 +/- 8 months, 20 patients received appropriate device therapy (antitachycardia pacing or shocks). No late complications occurred. One patient died at 3 months of pump failure; there were no sudden deaths. In conclusion, for exclusive pectoral implantation of transvenous ICDs, electrophysiologists should master both prepectoral and submuscular techniques. One can thus avoid potential skin erosion or need for abdominal implantation in patients with a thin layer of subcutaneous tissue. Finally, there are no differences in pacing or defibrillation thresholds between the two techniques.

Unusual features of right and left idiopathic ventricular tachycardia abolished by radiofrequency catheter ablation.

Two unusual cases are presented with idiopathic right and left ventricular tachycardia (IVT) with intriguing clinical and electrophysiological characteristics. The first patient with a sustained IVT of right ventricular outflow tract origin, and an electrophysiological mechanism suggesting reentry, had been resuscitated from cardiac arrest. The second patient had an IVT with a left bundle branch block morphology, which originated from the basal-septal region of the left ventricle (left ventricular outflow tract tachycardia). Both patients were cured with radiofrequency catheter ablation, guided by endocardial activation sequence and pace mapping.

Idiopathic long QT syndrome with late onset of bradycardia-dependent and short-coupled variant of torsade de pointes.

We report an idiopathic variant of the long QT syndrome in a 72 year old woman with a history of recurrent syncope over 3 years who presented with repeated episodes of cardiac arrest due to bradycardia-dependent torsade de pointes (TdP), which continued long after possible triggers were eliminated. During these episodes a short coupling interval of the first tacycardia beat was also observed. The patient's stormy course was only controlled with pacing. She received a permanent dual-chamber pacemaker and prophylactically a beta-blocker was added. Over the subsequent 14 months she has remained completely asymptomatic.

Successful percutaneous extraction of pacemaker leads with a novel (VascoExtor) pacing lead removal system.

A new pacing lead extraction system (VascoExtor, VascoMed, Germany) with a universally applicable locking stylet was used over a period of 12 months to extract 25 permanent pacemaker leads (mean implantation time 3.9 +/- 3.8 years) in 16 patients who had pacemaker infection (n = 13), lead dysfunction (n = 2), or before an automatic defibrillator implant (n = 1). With use of this system, we were able to successfully and safely remove 24 of 25 chronic pacing leads (96%) in 15 of 16 patients (93%) with sole use of the locking stylet in 81%, and with use of an array of ancillary tools in the remaining 19% of patients.