bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diagnosis of Amiodarone Pulmonary Toxicity with HighResolution Computerized Tomographic Scan
Authors: SINIAKOWICZ ROBERT M. , NARULA DHIRAJ , SUSTER BERNARD , STEINBERG JONATHAN S. 
Published: August 2003

Chest CT and Amiodarone Pulmonary Toxicity.
Introduction: Amiodarone pulmonary toxicity is a serious adverse effect that can be fatal. The diagnosis is difficult due to the nonspecificity of symptoms, clinical findings, and test results. Because of its high iodine content, amiodarone deposition can be detected by sensitive high‐resolution computed tomographic (CT) scan techniques. We hypothesized that pulmonary toxicity can be diagnosed more readily when these scans indicate the presence of increased attenuation of either pleural or pulmonary densities representing high iodine amiodarone deposits. Methods and Results: This case control study included 16 patients taking chronic amiodarone. Eight cases presented with severe respiratory and other symptoms and were matched with 8 controls, 4 with mild or chronic respiratory symptoms. All patients underwent high‐resolution CT of the chest. All cases had positive CT scan results demonstrating bilateral air‐space disease, parenchymal bands, and thickened septal and bronchiolitis obliterans. All minimally or asymptomatic patients had negative scans with no area of high attenuation. All cases had ≤ 1 lesion with high‐attenuation density. The cases were treated successfully by supportive care, discontinuation of amiodarone, and, rarely, corticosteroid therapy. Two cases had delayed diagnosis of amiodarone pulmonary toxicity and were managed successfully only ter CT. Conclusion: High‐resolution CT may be a valuable noninvasive test to aid in the diagnosis of amiodarone pulmonary toxicity in symptomatic patients.
Catheter Cryoablation of the Atrioventricular Node in Patients with Atrial Fibrillation: A Novel Technology for Ablation of Cardiac Arrhythmias
Authors: DUBUC MARC , KHAIRY PAUL , RODRIGUEZ‐SANTIAGO ANGEL , TALAJIC MARIO , TARDIF JEAN‐CLAUDE , THIBAULT BERNARD , ROY DENIS 
Published: August 2003

Percutaneous Catheter Cryoablation in Man.
Introduction: Recent animal studies demonstrated the feasibility and safety of applying percutaneous catheter cryoablation technology for ablation of arrhythmogenic sites. The studies also showed that reversible “ice mapping” can be performed before creating permanent lesions. We investigated the feasibility and safety of applying this new technology in man. Methods and Results: Cryoablation of the AV node (AVN) using a 9‐French quadripolar catheter with a 4‐mm electrode tip was attempted in 12 patients (mean age 67.8 ± 11.4 years) with refractory atrial fibrillation. Whereas technical issues prevented adequate tissue contact in two patients, complete AVN block was obtained in the remaining 10 patients after 4.8 ± 1.9 cryoapplications lasting 5.5 ± 0.2 minutes resulting in temperatures of −58.1°± 5.4°C. In all patients with sinus rhythm at the time of the procedure, cryomapping at warmer temperatures induced reversible AVN block and allowed confirmation of a successful site before definitive ablation. Intracardiac echocardiography was performed in three patients and allowed visualization of the cryocatheter‐endocardial contact and cryolesion formation. No major procedural complications were reported. After 6 months of follow‐up, 8 of 10 initially successful patients remained in complete block; 1 had partial recovery of AVN conduction manifested by atrial fibrillation with a slow ventricular response, and 1 fully recovered AVN conduction. Conclusion: (1) Catheter cryoablation of the AVN can be performed safely in man. (2) Reversible cryomapping is feasible and may offer an advantage over radiofrequency ablation. (3) Cryocatheterendocardial contact and cryolesion growth can be monitored with intracardiac echocardiography.
Ventricular Fibrillation Sensing and Detection by Implantable Defibrillators: Is One Better than the Others? A Prospective, Comparative Study
Authors: PANOTOPOULOS PANOGIOTIS , KRUM DAVID , AXTELL KATHI , DHALA ANWER , SRA JASBIR , AKHTAR MASOOD , DESHPANDE SANJAY 
Published: August 2003

ICD Sensing During VF.
Introduction: We prospectively compared the performance of the sensing and detection systems of three leading defibrillator manufacturers: Medtronic, Guidant, and Ventritex. Methods and Results: Ventricular fibrillation signal was digitally recorded during defibrillator implantation and subsequently played back sequentially to a Medtronic Micro Jewel II 7223Cx, a Guidant MINI II 1762, and a Ventritex Cadet V‐115C. The devices were programmed for single‐zone detection, at nominal settings. Rate cutoff was set at 320 msec (185/min for the MINI). We analyzed 253 episodes from 47 patients. Median undersensing was 0%, 2.1%, and 5.3% for the Jewel, MINI, and Cadet, respectively (P < 0.001 for each paired comparison). Detection time was 4.1 ± 1.6 seconds, 3.4 ± 1.6 seconds, and 4.3 ± 2.2 seconds for the Jewel, MINI, and Cadet, respectively (P < 0.001 between MINI‐Jewel and MINI– Cadet; P < 0.01 between Jewel‐Cadet). Delayed detection (detection time longer than the mean of all observations + 2 SD) occurred in 3 (1.2%), 7 (2.8%), and 18 (7.1%) episodes for the Jewel, MINI, and Cadet, respectively. Performance for all devices was worse when the short‐separation integrated bipolar lead was used and when the episode followed a failed high‐energy shock. Conclusion: Statistically significant differences were seen in sensing and detection performance among the devices and device/lead combinations during ventricular fibrillation. These differences are related to specific features of the respective devices and should be taken into account during clinical practice, as well as in future device development.
Electrocardiographic Prediction of Abnormal Genotype in Congenital Long QT Syndrome: Experience in 101 Related Family Members
Authors: KAUFMAN ELIZABETH S. , PRIORI SILVIA G. , NAPOLITANO CARLO , SCHWARTZ PETER J. , IYENGAR SUDHA , ELSTON ROBERT C. , SCHNELL AUDREY H. , GORODESKI EIRAN Z. , RAMMOHAN GUHAN , BAHHUR NAEL O. , CONNUCK DAVID , VERRILLI LINDA , ROSENBAUM DAVID S. , BROWN ARTHUR M. 
Published: August 2003

Prediction of Congenital Long QT Syndrome.
Introduction: Previous studies showed that diagnosing congenital long QT syndrome (LQTS) is difficult due to variable penetrance and genetic heterogeneity, especially when subjects from multiple families with diverse mutations are combined. We hypothesized that a combination of clinical and ECG techniques could identify gene carriers within a single family with congenital LQTS. Methods and Results: One hundred one genotyped members of a family with LQTS, including 26 carriers of a HERG mutation, underwent history and ECG analysis. Forty‐eight family members also underwent exercise testing with QT and T wave alternans (TWA) analysis and 24‐hour Holter monitoring with QT and heart rate variability analysis. A logistic regression model, which included age, gender, QTc, and QTc by age, provided the best prediction of gene carrier status, although there was substantial overlap (78%) of QTc among subjects with and without the mutation. QTc was not helpful as a discriminator in children ≤ 13 years. TWA (observed infrequently) did not add significantly to the model's ability to predict abnormal genotype. Conclusion: Even in this homogeneous LQTS population, the phenotype was so variable that clinical and detailed ECG analyses did not permit an accurate diagnosis of gene carrier status, especially in children. Sustained microvolt TWA was a specific (100%) but insensitive (18%) marker for LQTS. Its ability to predict risk of arrhythmia in this population remains to be determined. Genetic testing serves an essential role in screening for carriers of LQTS.
Reduction in Atrial Defibrillation Threshold by a Single Linear Ablation Lesion
Authors: WHITE JAMES B. , FOTUHI PARWIS C. , PEDOTO RAMON W. , CHATTIPAKORN NIPON , ROGERS JACK M. , IDEKER RAYMOND E. 
Published: August 2003

Single Lesion Lowers ADFT.
Introduction: This study investigated a hybrid approach to reduce the atrial defibrillation threshold (ADFT) by determining the effect of a single linear radiofrequency ablation (RFA) lesion on both the ADFT and activation patterns during atrial fibrillation (AF). Methods and Results: In 18 open chest sheep (45 to 57 kg), coil defibrillation electrodes were placed in a superior vena cava/right ventricular configuration. AF was induced by burst pacing and maintained with acetyl β‐methylcholine (2 to 42 μL/min). ADFTs were obtained before and after a linear RFA lesion was created in the left atrium (LAL; n = 6), right atrium (RAL; n = 6), or neither atrium as a control (n = 6). In animals receiving an LAL, a 504‐unipolar‐electrode plaque was sutured to the LA. For animals receiving an RAL, two 504‐electrode plaques were placed, one each on the LA and RA. From each plaque, activations were recorded before and after ADFT shocks, and organizational characteristics of activations were analyzed using algorithms that track individual wavefronts. In sham‐treated controls, the ADFT did not change. In contrast, LAL reduced ADFT energy 29%, from 4.5 ± 2.3 J to 3.2 ± 2.0 J (P < 0.05). RAL reduced ADFT energy 25%, from 2.0 ± 0.9 J to 1.5 ± 0.7 J (P < 0.05). AF activation was substantially more organized after RFA than before RFA for both the RAL‐ and LAL‐treated animals. Conclusion: A single RFA lesion in either the RA or LA reduces the ADFT in this sheep model. This decrease is associated with an increase in fibrillatory organization.
Chromanol 293B Inhibits Slowly Activating Delayed Rectifier and Transient Outward Currents in Canine Left Ventricular Myocytes
Authors: SUN ZHUO‐QIAN , THOMAS GEORGE P. , ANTZELEVITCH CHARLES 
Published: August 2003

Chromanol 293B on Ionic Currents.
Introduction: Drugs that selectively inhibit the slowly activating component of the delayed rectifier potassium current (IKs) are being considered as possible antiarrhythmic agents, because they produce more prolongation of action potential duration at fast rates with less transmural dispersion of repolarization compared with blockers of the rapidly activating component (IKr). Although the chromanol derivative chromanol 293B has been shown to be relatively selective in blocking IKs in some species, its selectivity is far from established. Methods and Results: The present study uses whole‐cell, patch‐clamp technique to examine the selectivity of this compound for inhibition of IKs in comparison with other repolarizing ionic currents, such as IKr, inward rectifier potassium current (IK1), transient outward current (Ito), and L‐type calcium current (ICa‐L) in canine left ventricular mid‐myocardial and endocardial cells. Chromanol 293B blocked IKs with an IC50 of 1.8 μM and Ito with an IC50 of 38 μM. Concentrations as high as 30 μM did not affect IK1, IKr, or ICa‐L. Higher concentrations of chromanol 293B (100 μM) caused a slight, but statistically insignificant, inhibition of IKr. Conclusion: Our results indicate that chromanol 293B is a relatively selective blocker of IKs in canine left ventricular myocytes.
Properties and Substrate of Slow Pathway Exposed with a Compact Node Targeted Fast Pathway Ablation in Rabbit Atrioventricular Node
Authors: LIN LI‐JEN , BILLETTE JACQUES , MEDKOUR DJAMILA , REID MARIE CLAUDE , TREMBLAY MAURICE , KHALIFE KARIM 
Published: August 2003

Selective Slow Nodal Pathway Model.
Introduction: The properties and substrates of slow and fast AV nodal pathway remain unclear. This applies particularly to the slow pathway (SP), which is largely concealed by fast pathway (FP) conduction. We designed a new FP ablation approach that exposes the SP over the entire cycle length range and allows for its independent characterization and ablation. Methods and Results: Premature stimulation was performed before and after FP ablation with 5.4 ± 1.9 lesions (300‐μm diameter each; overall lesion size 1.4 ± 0.5 mm) targeting the junction between perinodal and compact node tissues in seven rabbit heart preparations. The resulting SP recovery curve and control curve had the same maximum nodal conduction time (165 ± 22 msec vs 164 ± 24 msec; P = NS) and effective refractory period (101 ± 10 msec vs 100 ± 9 msec; P = NS). The two curves covered the same cycle length range. However, the SP curve was shifted up with respect to control one at intermediate and long cycle lengths and thus showed a longer minimum nodal conduction time (81 ± 15 msec vs 66 ± 10 msec; P < 0.01) and functional refractory period (180 ± 11 msec vs 170 ± 12 msec; P < 0.05). The SP curve was continuous and closely fitted by a single exponential function. Small local lesions (2 ± 1) applied to the posterior nodal extension resulted in third‐degree nodal block in all preparations. Conclusion: The posterior nodal extension can sustain effective atrial‐His conduction at all cycle lengths and account for both the manifest and concealed portion of SP. Slow and FP conduction primarily arise from the posterior extension and compact node, respectively.
Incidence and Clinical Significance of Inducible Atrial Tachycardia in Patients with Atrioventricular Nodal Reentrant Tachycardia
Authors: STICHERLING CHRISTIAN , TADA HIROSHI , GREENSTEIN RADMIRA , CHAN CHI‐WO , CHOUGH STEVEN P. , BAKER ROBERT L. , WASMER KRISTINA , ORAL HAKAN , PELOSI FRANK , KNIGHT BRADLEY P. , STRICKBERGER S. ADAM , MORADY FRED 
Published: August 2003

Significance of Atrial Tachycardia.
Introduction: The purpose of this prospective study was to determine the prevalence and clinical significance of inducible atrial tachycardia in patients undergoing slow pathway ablation for AV nodal reentrant tachycardia who did not have clinically documented episodes of atrial tachycardia. Methods and Results: Twenty‐seven (15%) of 176 consecutive patients who underwent slow pathway ablation for AV nodal reentrant tachycardia were found to have inducible atrial tachycardia with a mean cycle length of 351 ± 95 msec. The atrial tachycardia was sustained in 7 (26%) of 27 patients and was isoproterenol dependent in 20 patients (74%). The atrial tachycardia was not ablated or treated with medications, and the patients were followed for 9.7 ± 5.8 months. Six (22%) of the 27 patients experienced recurrent palpitations during follow‐up. In one patient each, the palpitations were found to be due to sustained atrial tachycardia, nonsustained atrial tachycardia, recurrence of AV nodal reentrant tachycardia, paroxysmal atrial fibrillation, sinus tachycardia, and frequent atrial premature depolarizations. Thus, only 2 (7%) of 27 patients with inducible atrial tachycardia later developed symptoms attributable to atrial tachycardia. Conclusion: Atrial tachycardia may be induced by atrial pacing in 15% of patients with AV nodal reentrant tachycardia. Because the vast majority of patients do not experience symptomatic atrial tachycardia during follow‐up, treatment for atrial tachycardia should be deferred and limited to the occasional patient who later develops symptomatic atrial tachycardia.
Clinical Usefulness of a Multielectrode Basket Catheter for Idiopathic Ventricular Tachycardia Originating from Right Ventricular Outflow Tract
Authors: AIBA TAKESHI , SHIMIZU WATARU , TAGUCHI ATSUSHI , SUYAMA KAZUHIRO , KURITA TAKASHI , AIHARA NAOHIKO , KAMAKURA SHIRO 
Published: August 2003

Basket Catheter in Idiopathic VT.
Introduction: It often is difficult to determine the optimal ablation site for idiopathic ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT) when the VT or premature ventricular complex (PVC) does not occur frequently. The aim of our study was to evaluate the usefulness of a multielectrode basket catheter for ablation of idiopathic VT originating from the RVOT. Methods and Results: Radiofrequency (RF) catheter ablation was performed using a 4‐mm tip, quadripolar catheter in 50 consecutive patients with 81 VTs originating from the RVOT with (basket group = 25 patients with 45 VTs) or without (control group = 25 patients with 36 VTs) predeployment of a multielectrode basket catheter composed of 64 electrodes. Deployment of the multielectrode basket catheter was possible and safe in all 25 patients in the basket group. Ablation was successful in 25 (100%) of 25 patients in the basket group and in 22 (88%) of 25 patients in the control group. The total number of RF applications and the number of RF applications per PVC morphology did not differ between the two groups. However, both the fluoroscopic and ablation procedure times per PVC morphology were shorter in the basket group than in the control group (36.8 ± 14.1 min vs 52.0 ± 32.5 min, P = 0.04; 60.0 ± 14.6 vs 81.5 ± 51.2 min, P = 0.05). This difference was more pronounced in the 29 patients in whom VT or PVC was not frequently observed. Conclusion: The multielectrode basket catheter is safe and useful for determining the optimal ablation site in patients with idiopathic VT originating from the RVOT, especially in those without frequent VT or PVC.
Worldwide Clinical Experience with a New Dual‐Chamber Implantable Cardioverter Defibrillator System
Authors: SCHOELS WOLFGANG , SWERDLOW CHARLES D. , JUNG WERNER , STEIN KENNETH M. , SEIDL KARLHEINZ , HAFFAJEE CHARLES J. 
Published: August 2003

New Dual‐Chamber ICD.
Introduction: Management of atrial tachyarrhythmias represents a significant challenge in patients with implantable cardioverter defibrillators (ICDs). Drug therapy of these arrhythmias is limited by moderate efficacy, ventricular proarrhythmia, and drug‐device interactions. This study tested the safety and efficacy of a new dual‐chamber ICD to detect and treat atrial as well as ventricular tachyarrhythmias. Methods and Results: A dual‐chamber ICD (Medtronic 7250 Jewel AF) was implanted in 293 of 303 patients at 49 centers in Europe, Canada, and North America. Specific data were collected at implant and during a mean follow‐up period of 7.9 ± 4.7 months. There were no clinically evident failures to detect and treat ventricular arrhythmias. In patients with at least one of the dual‐chamber detection criteria activated, 1,056 of 1,192 episodes of ventricular tachycardia or fibrillation detected were judged to be appropriate (89% positive predictive accuracy). Therapy efficacy was 100% in the ventricular fibrillation zone and 98% in the ventricular tachycardia zone. Positive predictive accuracy for detection of atrial episodes was 95% (1,052/1,107). For episodes classified as atrial tachycardia by the device, the efficacy of atrial antitachycardia pacing and high‐frequency (50‐Hz) burst pacing was 55% and 17%, respectively. High‐frequency burst pacing terminated 16.8% of episodes classified as atrial fibrillation, and atrial defibrillation had an estimated efficacy of 76%. The actuarial estimates of 6‐month complication‐free survival and total survival were 88% and 94%, respectively. Conclusion: This novel dual‐chamber ICD is capable of safely and effectively discriminating atrial from ventricular tachyarrhythmias and of treating atrial tachyarrhythmias without compromising detection and treatment of ventricular tachyarrhythmias.
Radiofrequency Catheter Ablation of Idiopathic Left Ventricular Outflow Tract Tachycardia: Utility of Intracardiac Echocardiography
Authors: LAMBERTI FILIPPO , CALO' LEONARDO , PANDOZI CLAUDIO , CASTRO ANTONIO , LORICCHIO MARIA LUISA , BOGGI AUGUSTO , TOSCANO SALVATORE , RICCI RENATO , DRAGO FABRIZIO , SANTINI MASSIMO 
Published: August 2003

Idiopathic LVOT Tachycardia.
Introduction: The site of origin of idiopathic ventricular tachycardia (VT) arising from the left ventricular outflow tract (LVOT) may be closely related to the aortic valve leaflets, and radiofrequency (RF) delivery potentially can damage them. Intracardiac echocardiography (ICE) can identify accurately the ablation electrode and anatomic landmarks, and contact with the endocardium can be easily assessed. The aim of this study was to define the utility and the accuracy of ICE in guiding RF ablation of idiopathic VT of the LVOT. Methods and Results: Five consecutive patients (all men; mean age 20.4 years, range 16 to 25) symptomatic for idiopathic VT underwent RF ablation. A 9‐French, in‐sheath catheter with a 9‐MHz ultrasound transducer was inserted through the femoral vein and positioned in the His‐bundle region or right ventricular outflow tract to provide a clear view of the aortic root. Local earliest ventricular activation during tachycardia and pace mapping were used to identify the ablation site. Idiopathic VT was ablated successfully in all patients using a median of two RF pulses, delivered during tachycardia. High‐resolution images of the aortic valve and ablation electrode were achievable in all cases. Direct vision of ablation electrode‐endocardial contact in the outflow tract was assessed easily in all patients. Conclusion: Idiopathic VT of the LVOT can be treated successfully with RF ablation. ICE can accurately guide catheter ablation and identify anatomic landmarks, endocardial contact, and ablation electrode movement.
Female Gender is a Risk Factor for Drug‐Induced Long QT and Cardiac Arrhythmias in an In Vivo Rabbit Model
Authors: LU HUA RONG , REMEYSEN PAUL , SOMERS KATRIEN , SAELS AN , DE CLERCK FRED 
Published: August 2003

Gender Differences in Drug‐Induced LQT and TdP.
Introduction: Clinical observations and in vitro experimental data indicate that females have a longer QT interval than males, which is associated with a higher risk of drug‐induced cardiac arrhythmias. Little is known about this gender difference in anesthetized animals, which may affect the outcome of in vivo drug tests. Methods and Results: We evaluated potential gender differences in ventricular repolarization (QT, QTc, JT, and JTc interval) and its dispersion, as well as in its response to dofetilide, an IKr blocker, in anesthetized rabbits challenged with the α1‐adrenoceptor agonist methoxamine. A 12‐lead ECG was recorded during the experiments. At baseline, there were no significant gender differences in ventricular repolarization values in male and female rabbits under anesthesia. Dofetilide (0.04 mg/kg/min IV for 60 min; n = 10 per gender) produced marked prolongation of the ventricular repolarization time and its dispersion, associated with a high incidence of polymorphic ventricular tachycardia (PVT; 100% in females vs 80% in males) and ventricular fibrillation (VF; 80% in females vs 50% in males; P > 0.05). QT and JT interval at 2 minutes as well as QT and JT dispersion at 10 and 30 minutes during dofetilide infusion were significantly higher in female than in male rabbits. After 30 minutes of dofetilide infusion, 10 of 10 female rabbits had severe cardiac arrhythmias (complete AV block, PVT, or VF), so ECG parameters were impossible to assess (vs 3/10 males with severe cardiac arrhythmias; P < 0.05). During dofetilide infusion, female rabbits developed complete AV block, PVT, or VF at doses about 50% lower than those given to males. Conclusion: The present study indicates that female rabbits are more susceptible to drug‐induced long QT and cardiac arrhythmias than are male rabbits; therefore, female rabbits are more appropriate for testing drug‐induced cardiac arrhythmias.