bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Atrial Electrical Remodeling on Atrial Defibrillation Thresholds
Authors: EVERETT THOMAS H. , LI HUI , MANGRUM J. MICHAEL , MASTRANGELO CHRISTINA , HAINES DAVID E.
Published: July 2003

EVERETT, T.H. et al.: The Effects of Atrial Electrical Remodeling on Atrial Defibrillation Thresholds. Electrical remodeling of atrial fibrillation may account for the increase in atrial defibrillation thresholds over time. The aim of this study was to examine the time course of electrical remodeling and the benefit of early defibrillation on the defibrillation threshold. Twenty‐six mongrel dogs weighing 27.6 ± 3.3 kg were induced into AF by repeated high output burst atrial pacing. Eight dogs were paced for multiple time periods of 5, 20, 40, and 60 minutes. Five dogs each had burst pacing for 4 hours and 8 hours, and eight dogs were paced at a high rate (640 beats/min) for 48 hours. Biphasic atrial defibrillation shocks with a pulse width of 3/3 ms synchronized to the left apical electrogram were delivered to coil electrode catheters positioned in the lateral left and right atria. Defibrillation voltage was increased from 50 V in 20‐ to 30‐V steps until defibrillation was successful. As the pacing period increased, a decrease in atrial fibrillation cycle lengths and atrial effective refractory period was not observed before 8 hours. Similarly, the defibrillation threshold did not change significantly until the 8‐hour pacing period was reached. The defibrillation thresholds were 69 ± 28 V for 5 minutes, 64 ± 20 V for 20 minutes, 99 ± 85 V for 40 minutes, 78 ± 51 V for 60 minutes, 78 ± 38 V for 4 hours, 124 ± 33 V for 8 hours, and 133 ± 32 V for 48 hours (mean ± SD) (P < 0.05). Atrial electrical remodeling in a rapid atrial pacing canine model is not observed until after 4 hours of burst atrail pacing. The atrial defibrillation threshold increases with increasing duration of burst atrial pacing, and follows a similar time course to other parameters of electrical remodeling.
Holter Monitoring in AL Amyloidosis: Prognostic Implications
Authors: PALLADINI GIOVANNI , MALAMANI GIANDOMENICO , CÒ FRANCESCA , PISTORIO ANGELA , RECUSANI FRANCO , ANESI ERNESTO , GARINI PIETRO , MERLINI GIAMPAOLO
Published: July 2003

PALLADINI, G., et al.: Holter Monitoring in AL Amyloidosis: Prognostic Implications. The heart is involved in more than one third of patients with primary (AL) amyloidosis at diagnosis and it is by far the most common cause of death. Rhythm and conduction abnormalities generally represent the terminal event. The aims of this study were to determine the spectrum of Holter abnormalities found in AL amyloidosis and to assess their prognostic significance, particularly in relation to sudden death. Fifty‐one patients with AL amyloidosis were included, and all of them had a complete history, physical examination, two‐dimensional echocardiography, and 24‐hour Holter monitoring. Fifty‐five percent of these patients had echographic signs of heart involvement and 23% had heart failure. Complex ventricular arrhythmias were found in 57% of patients, couplets in 29%, and nonsustained ventricular tachycardia in 18%. Overall median survival was 23.4 months. Congestive heart failure, echocardiographic abnormalities, and Holter abnormalities adversely affected survival. The multivariate analysis demonstrated that interventricular septum thickness and couplets were independent predictors of survival. The presence of couplets correlated with sudden death. Holter monitoring may contribute to assessing the prognosis of patients with AL amyloidosis.
Washing Machine Associated 50 Hz Detected As Ventricular Fibrillation by An Implanted Cardioverter Defibrillator
Authors: SABATÉ XAVIER , MOURE CRISTINA , NICOLÁS JOAN , SEDÓ MIQUEL , NAVARRO XAVIER
Published: July 2003

SABATÉ, X., et al.: Washing Machine Associated 50 Hz Detected As Ventricular Fibrillation by An Implanted Cardioverter Defibrillator. This case report describes a patient with an automatic ICD who suffered a defibrillation shock without warning symptoms. An electrical interference can be observed in the stored EGM of the episode. The patient explained that the moment he felt the shock he was touching a washing machine. After correct grounding of this machine the patient did not suffer more inappropriate shocks.
Quadruple Pads Approach for External Cardioversion of Atrial Fibrillation
Authors: MARROUCHE NASSIR F. , BARDY GUST H. , FRIELITZ HANS J. , GÜNTHER JENS , BRACHMANN JOHANNES
Published: July 2003

MARROUCHE, N.F., et al.: Quadruple Pads Approach for External Cardioversion of Atrial Fibrillation. This study examined the alternative of transthoracic quadruple pads shock delivery of two simultaneous 360‐J shocks to convert refractory AF in patients failing standard external cardioversion. Forty‐six patients (mean age 58 ± 11 years, 23 men) with chronic AF (duration 14 ± 17 months, range 1–60 months) were included. The left atrial diameter was 47 ± 7 mm. The left ventricular ejection fraction was 59 ± 11%. Antiarrhythmic drugs had failed to convert 44 (96%) of these patients. All patients underwent conventional external transthoracic cardioversion with pads applied in the antero‐apical position using energy settings of 200 and 360 J, consecutively. In all patients who failed conventional cardioversion, quadruple pads were applied. Quadruple pads consisted of four pads, two in the antero‐posterior position and two in a second apex‐posterior position. Standard cardioversion to sinus rhythm was successful in 19 (41%) patients after use of a single 200‐J shock and an additional 8 (17%) after a single 360‐J shock. The total success rate was 58% after conventional cardioversion. The quadruple pads were successful in 14 (74%) of the remaining 19 patients. Four of the five patients who failed the quadruple pads approach subsequently also failed internal cardioversion. Thus, the cardioversion success rate was increased from 48% using the conventional approach to 89% using the quadruple pads approach. Quadruple pads external cardioversion is highly effective in converting chronic AF refractory to standard shock protocols to sinus rhythm. Moreover, the failure of the quadruple pads approach seems to predict poor response to internal cardioversion.
Three‐Dimensional Distribution of Bipolar Atrial Electrogram Voltages in Patients with Congenital Heart Disease
Authors: DE GROOT NATASJA M.S. , KUIJPER AAF F.M. , BLOM NICO A. , BOOTSMA MARIANNE , SCHALIJ MARTIN J.
Published: July 2003

DE GROOT, N.M.S., et al.: Three‐Dimensional Distribution of Bipolar Atrial Electrogram Voltages in Pa‐tients with Congenital Heart Disease. Voltage differences might be used to distinguish normal atrial tissue from abnormal atrial tissue. This study was aimed at identifying lowest voltage areas in patients with atrial tachycardia after surgical correction of congenital heart disease and to evaluate if identification of these areas in diseased hearts facilitates selection of critical conduction pathways in reentrant circuits as target sites for catheter ablation. Ten patients (four men, age 39 ± 15 years) with normal sized atria and atrioventricular reciprocating tachycardia (control group) and ten patients (5 men, 32 ± 7 years) with congenital heart disease and postoperative atrial tachycardia (CL 281 ± 79 ms) referred for radiofrequency catheter ablation were studied. Mapping and ablation was guided by a three‐dimensional electroanatomic mapping system (CARTO) in all patients. In the control group, voltage maps were constructed during sinus rhythm and during tachycardia to evaluate the voltage distribution. The amplitude of bipolar signals was 1.90 ± 1.45 mV (0.11–8.12 mV, n = 660) during sinus rhythm and 1.45 ± 1.66 mV (0.12–5.83 mV, n = 440, P < 0.05) during atrioventricular reciprocating tachycardia. In the study group, the amplitude of 1,962 bipolar signals during tachycardia was 1.01 ± 1.19 mV (0.04–9.40 mV), which differed significantly from the control group during tachycardia (P < 0.0001). No significant difference in the tachycardia cycle length was found (P < 0.05) between the control and study groups. As the lowest voltage measured in normal hearts was 0.1 mV, this value was used as the upper limit of the lowest voltage areas in the patients with congenital heart disease. These areas were identified by detailed voltage mapping and represented by a gray color. Activation and propagation maps were then used to select critical conduction pathways as target sites for ablation. These sites were characterized by fragmented signals in all patients. Ablation resulted in termination of the tachycardia in eight (80%) of ten patients. Complications were not observed. Identification of the lowest voltage areas using a cut‐off value of 0.1 mV in congenital heart disease patients with postoperative atrial reentrant tachycardia facilitated the selection of critical conduction pathways as target sites for ablation.
Bidirectional Defibrillation Using Implantable Defibrillators: A Prospective Randomized Comparison Between Pectoral and Abdominal Active Generators
Authors: SANDSTEDT BENGT , KENNERGREN CHARLES , EDVARDSSON NILS
Published: July 2003

SANDSTEDT, B., et al.: Bidirectional Defibrillation Using Implantable Defibrillators: A Prospective Randomized Comparison Between Pectoral and Abdominal Active Generators. The objective of this study was to compare the effects of active abdominal and pectoral generator positions on DFTs in a bidirectional tripolar ICD system. Twenty‐five consecutive patients had ICD systems implanted under general anesthesia. A transvenous single lead bipolar defibrillation system and an active 57‐cc test emulator in the abdominal and pectoral positions were used in the same patient. A randomized, alternating stepdown protocol was used starting at 15 J with 3‐J decrements until failure. The mean implantation time was 114 ± 23 minutes, the mean arrhythmia duration was 14.5 ± 1.5 seconds, and the mean recovery time was 5.4 ± 1.1 minutes. The mean DFTs in the abdominal and pectoral positions were 10.9 ± 5.1 and 9.7 ± 5.2 J, respectively (NS), the mean intraindividual DFT difference (abdominal minus pectoral) was −0.89 ± 4.15 J (range −9.5 to + 5.8 J). The 95% confidence interval showed a −2.60 to + 0.82 J mean difference (NS). The DFT was < 15 J in 72% and 88% of the patients and the defibrillation impedance was 41 ± 3 and 44 ± 3 Ω, abdominal versus pectoral positions. There was no difference in DFT between active abdominal and pectoral generator bidirectional tripolar defibrillation. The pectoral position may be considered the primary option, but in cases of high DFTs the abdominal site should be considered an alternative to adding a subcutaneous patch. In some patients, the anatomy may favor an abdominal position. Possible differences in the long‐term functionality on the leads are not yet well known and need to be further evaluated.
Response of Atrial Fibrillatory Activity to Carotid Sinus Massage in Patients with Atrial Fibrillation
Authors: BOLLMANN ANDREAS , WODARZ KARSTEN , ESPERER HANS‐DIETER , TOEPFFER INES , KLEIN HELMUT U.
Published: July 2003

BOLLMANN, A., et al.: Response of Atrial Fibrillatory Activity to Carotid Sinus Massage in Patients with Atrial Fibrillation. In some cases carotid sinus massage (CSM) may induce AF, whereas it may terminate AF in others. The purpose of this study was to investigate the influence of CSM on atrial fibrillatory frequency using spectral analysis of the surface ECG. Continuous ECG recordings were made in 19 patients (12 men, 7 women, mean age 61 ± 11 years) with AF. Unilateral CSM was performed in the standard fashion to one randomized bifurcation of the carotid artery at a time. Ventricular rate and fibrillatory frequency were assessed in 30‐second ECG segments at baseline and during CSM. The frequency content of the fibrillatory baseline was quantified using digital signal processing (filtering, subtraction of averaged QRST complexes, and Fourier transformation). CSM resulted in a relative change in fibrillatory frequency of 4.5 ± 3.9% (range 0%–13%). In 8 (42%) patients an increase in fibrillatory frequency was found (6.4 ± 0.5 vs 6.8 ± 0.5 Hz, P = 0.012). In 9 (47%) patients a decrease in fibrillatory frequency occurred (6.5 ± 0.8 vs 6.1 ± 0.8 Hz, P = 0.008) without AF termination. The remaining two patients showed no change in fibrillatory frequency. CSM on the contralateral side after 2 minutes produced fibrillatory frequency changes in the same direction in all patients with a good reproducibility in its magnitude (r = 0.59, P = 0.05). Calcium channel blockers were more frequently used (78% vs 25%, P = 0.044) in patients with a decrease in fibrillatory frequency compared to patients with a frequency increase. There were no significant changes in ventricular rate during CSM. In conclusion, two different responses of atrial fibrillatory frequency to CSM were found. This might explain why CSM may facilitate AF induction in some cases and AF termination in others. Calcium channel blocker treatment may prevent an increase in fibrillatory frequency provoked by CSM suggesting a blunted electrical remodeling process.
Reduction of Pacing Output Coupling Capacitance for Sensing the Evoked Response
Authors: SPERZEL JOHANNES , NEUZNER JÖRG , SCHWARZ TORSTEN , ZHU QINGSHENG , KÖNIG ANDREAS , KAY G. NEAL
Published: July 2003

SPERZEL, J., et al.: Reduction of Pacing Output Coupling Capacitance for Sensing the Evoked Response. Sensing of the intracardiac evoked response (ER) after a pacing stimulus has been used in implantable pacemakers for automatic verification of capture. Reliable detection of ER is hampered by large residual afterpotentials associated with pacing stimuli. This led to the development of various technological solutions, like the use of triphasic pacing pulses and low polarizing electrode systems. This study investigated the effect of reducing the coupling capacitance (CC) in the pacemaker output circuitry on the magnitude of afterpotential, and the ability to automate detection of ventricular evoked response. A CC of 2.2 μF and four different blanking and recharge time settings were clinically tested to evaluate its impact on sensing of the ventricular ER and pacing threshold. Using an automatic step‐down threshold algorithm, 54 consecutive patients, aged 70 ± 10 years with acutely (n = 27) or chronically (n = 27) implanted ventricular pacing leads were enrolled for measurement testing. Routine measurements, using a standard pacing system analyzer (PSA), were (mean ± SD) impedance 569 ± 155 Ω, R wave amplitude baseline to peak 9.8 ± 3.7 mV and threshold 0.9 ± 0.7 V at 0.4‐ms pulse width. This new capture verification scheme, based on a CC of 2.2 μF and recharge/blanking timing setting of 10/12 ms, was successful in 52 patients which is equivalent to a success rate of 96%. In a subgroup of 26 patients implanted with bipolar ventricular leads (10 chronic, 16 acute), data were collected in unipolar (UP) and bipolar (BP) pace/sense configurations. Also, ER signals were recorded with two different band‐pass filters: a wider band (WB) of 6–250 Hz and a conventional narrow band (NB) of 20–100Hz. WB sensing from UP lead configuration yielded statistically significant larger signal to artifact ratios (SAR) than the other settings (P < 0.01). A dedicated unipolar ER sensing configuration using a small output capacitor and a wider band‐pass filter enables adequate automatic capture verification, without any restrictions on pacing lead models or pacing/sensing configurations.
Subthreshold Stimulation at the Focal Origin of Para‐Hisian‐Located Ectopic Atrial Tachycardia
Authors: WEISS CHRISTIAN , VENTURA RODOLPHO , MEINERTZ THOMAS , WILLEMS STEPHAN
Published: July 2003

WEISS, C., et al.: Subthreshold Stimulation at the Focal Origin of Para‐Hisian‐Located Ectopic Atrial Tachycardia. The focal origin of ectopic atrial tachycardia (EAT) is occasionally located in the superoparaseptal region adjacent to the bundle of HIS. Radiofrequency catheter ablation (RFCA) of EAT in this anatomic location implies the potential hazard of adverse impairment of the AV conduction. Therefore, careful precise mapping is mandatory. Subthreshold stimulation as defined as the delivery of noncaptured low energy pulses has been introduced as an additional mapping technique for slow pathway ablation in the setting of AV nodal reentrant tachycardia and other reentrant tachycardia. A patient with a right superoparaseptal EAT focus, in which subthreshold stimulation (STS) could determine the site of successful subsequent RFCA is described. During STS with EAT termination no AV conduction disturbances, junction‐escape rhythms or atrial capture could be recorded. Thus STS may be used as an additional mapping tool to identify successful ablation sites in EAT.
Evaluation of a Single Stage Nitroglycerin Tilt Table Test for Diagnosis of Neurally Mediated Syncope
Authors: ZENG CHUNYU , LIU GUANGYAO , YANG CHENGMING , SUN WEI , WANG YIELI , HE DUOFEN
Published: July 2003

ZENG, C., et al.: Evaluation of a Single Stage Nitroglycerin Tilt Table Test for Diagnosis of Neurally Mediated Syncope. The purpose of this study was to compare clinical outcomes between a single stage headup tilt table test (HUT) with infusion of 3.44 μg/kg per hour of nitroglycerin and a conventional multistage test with infusion of nitroglycerin from 1.72 μg/kg per hour to 5.16 μg/kg per hour in five successive stages. Thirty‐seven patients with recurrent syncope underwent both tests in a prospective, randomized, crossover fashion. During single stage HUT, a positive response occurred in 24 (64.9%) patients with unexplained syncope, an exaggerated response occurred in 3 (8.1%), a negative response in 7 (18.9%), and drug intolerance in 3 (8.1%). During the multistage HUT, these percentages were 62.2%, 16.2%, 13.5%, and 8.1%, respectively. Twenty healthy control subjects were involved in both tests. One of the control subjects had a positive response to single stage HUT, and two (10%) patients to multistage HUT. The duration of the test in single stage HUT was shorter than that in multistage HUT (8.6 ± 10.3 vs 38.6 ± 32.1 minutes, P < 0.01). The results showed that the single stage HUT was a fairly sensitive, specific, and a time‐efficient test for provoking neurally mediated syncope.
Risk of Torsades de Pointes From Oral Erythromycin with Concomitant Carbimazole (Methimazole) Administration
Authors: KOH TAT W.
Published: July 2003

KOH, T.W.: Risk of Torsades de Pointes From Oral Erythromycin with Concomitant Carbimazole (Methimazole) Administration. There are many reports of intravenous erythromycin causing QT prolongation and torsades de pointes, but this complication is seldom ascribed to orally administered erythromycin, which is by far the most commonly prescribed route. This report describes a case of torsades de pointes associated with oral erythromycin as a result of a previously undescribed interaction with carbimazole, an antithyroid drug that is metabolized to the active drug methimazole, and the potential pharmacokinetic and pharmacodynamic mechanisms are highlighted.
AAIR Versus DDDR Pacing in the Bradycardia Tachycardia Syndrome: A Prospective, Randomized, Double‐blind, Crossover Trial
Authors: SCHWAAB BERNHARD , KINDERMANN MICHAEL , SCHÄTZER‐KLOTZ DOROTHEA , BERG MONIKA , FRANOW HENDRIK , FRÖHLIG GERD , SCHIEFFER HERMANN
Published: July 2003

SCHWABB, B., et al.: AAIR Versus DDDR Pacing in the Bradycardia Tachycardia Syndrome: A Prospective, Randomized, Double‐blind, Crossover Trial. In 19 patients paced and medicated for bradycardia tachycardia syndrome (BTS), AAIR and DDDR pacing were compared with regard to quality of life (QoL), atrial tachyarrhythmia (AFib), exercise tolerance, and left ventricular (LV) function. Patients had a PQ interval ≤ 240 ms during sinus rhythm, no second or third degree AV block, no bundle branch block, or bifascicular block. In DDDR mode, AV delay was optimized using the aortic time velocity integral. After 3 months, QoL was assessed by questionnaires, patients were investigated by 24‐hour Holter, cardiopulmonary exercise testing (CPX) was performed, and LV function was determined by echocardiography. QoL was similar in all dimensions, except dizziness, showing a significantly lower prevalence in AAIR mode. The incidence of AFib was 12 episodes in 2 patients with AAIR versus 22 episodes in 7 patients with DDDR pacing (P = 0.072). In AAIR mode, 164 events of second and third degree AV block were detected in 7 patients (37%) with pauses between 1 and 4 seconds. During CPX, exercise duration and work load were higher in AAIR than in DDDR mode (423 ± 127 vs 402 ± 102 s and 103 ± 31 vs 96 ± 27 Watt, P < 0.05). Oxygen consumption (VO2), was similar in both modes. During echocardiography, only deceleration of early diastolic flow velocity and early diastolic closure rate of the anterior mitral valve leaflet were higher in DDD than in AAI pacing (5.16 ± 1.35 vs 3.56 ± 0.95 m/s2 and 69.2 ± 23 vs 54.1 ± 26 mm/s, P < 0.05). As preferred pacing mode, 11 patients chose DDDR, 8 patients chose AAIR. Hence, AAIR and DDDR pacing seem to be equally effective in BTS patients. In view of a considerable rate of high degree AV block during AAIR pacing, DDDR mode should be preferred for safety reasons.
Derangement of Heart Rate Variability During a Catastrophic Earthquake: A Possible Mechanism for Increased Heart Attacks
Authors: LIN LIAN‐YU , WU CHAU‐CHUNG , LIU YEN‐BIN , HO YI‐LUUN , LIAU CHIAO‐SUONG , LEE YUAN‐TEH
Published: July 2003

LIN, L.‐Y., et al.: Derangement of Heart Rate Variability During a Catastrophic Earthquake: A Possible Mechanism for Increased Heart Attacks. At 1:47 AM on September 21, 1999, the middle part of Taiwan was struck by a major earthquake measuring 7.3 on the Richter scale. It has been shown that the mental stress caused by an earthquake could lead to a short‐ or long‐term increase in frequency of cardiac death probably through activation of the sympathetic nervous system. The aim of this study was to investigate the effects of emotional stress on the autonomic system during an actual earthquake. Fifteen patients receiving a 24‐hour Holter ECG study starting from 10 ± 4 hours before the onset of the earthquake were included for the analysis of time‐ and frequency‐domains of heart rate variability (HRV) at several time periods. A 24‐hour Holter study recorded 2–6 months before the earthquake in 30 age‐ and sex‐matched subjects served as the control group. Heart rate and the low frequency (LF) to high frequency (HF) ratio increased significantly after the earthquake and were attributed mainly to the withdrawal of the high frequency component (parasympathetic activity) of HRV. Sympathetic activation was blunted in elderly subjects > 60 years old. The concomitant ST‐T depression observed in the Holter study correlated with a higher increment of LF as compared to HF components. The changes observed in HRV recovered completely 40 minutes following the earthquake. The derangement of HRV results from the withdrawal of the parasympathetic component and the arousal of sympathetic activity by the stressful earthquake. However, this autonomic derangement returned towards normal 40 minutes following the earthquake.
Role of Endothelin in Modulation of Heart Rate Variability in Patients with Decompensated Heart Failure
Authors: ARONSON DORON , MITTLEMAN MURRAY A. , BURGER ANDREW J.
Published: July 2003

ARONSON, D., et al.: Role of Endothelin in Modulation of Heart Rate Variability in Patients with Decompensated Heart Failure. Endothelin–1 (ET–1) can modulate central and peripheral sympathetic outflow. However, if increased ET–1 levels contribute to autonomic perturbations in the setting of congestive heart failure (CHF) is not known. The purpose of this study was to determine if increased ET–1 levels contribute to the depressed HRV in patients with CHF. Sixty‐four patients were admitted to the hospital for treatment of decompensated CHF (mean age 59 ± 12 years, NYHA Classes III [72%] and IV [28%]). Time– and frequency‐domain HRV measures were obtained from 24‐hour Holter recordings. Neurohormonal activation was assessed by measuring plasma renin activity (PRA), aldosterone, norepinephrine, and ET–1 levels. Among the time‐domain HRV indices, ET–1 correlated negatively with the standard deviation of RR intervals (SDNN) (r =– 0.38, P = 0.002) and standard deviation of all 5‐minute mean RR intervals (SDANN5) (r =– 0.48, P < 0.0001), but not with time‐domain indices indicative of parasympathetic modulation. Among the frequency‐domain HRV indices, ET–1 correlated negatively with the total power (r =– 0.32, P = 0.01) and ultralow frequency power (ULF) (r =– 0.43, P = 0.0004), but not with indices of parasympathetic (high frequency) or sympathovagal (low frequency) modulation. Using multiple linear regression, adjusting for clinical parameters, drug therapies, and other neurohormones, the strong negative relationship between ET–1 and SDNN (P = 0.027), SDANN5 (P = 0.002), and ULF power (P = 0.017) persisted. In conclusion, ET–1 may play an important role in the autonomic dysfunction characteristic of CHF. The correlation between ET–1 levels and prognostically important indices of overall HRV suggests that these HRV measures are better markers of neurohormonal activation in CHF, which may partially account for their greater discriminatory power for risk stratification.
Catheter Ablation of Incisional Atrial Tachycardia Using a Novel Mapping System: LocaLisa
Authors: MOLENSCHOT MIRELLA , RAMANNA HEMANTH , HOORNTJE THEO , WITTKAMPF FRED , HAUER RICHARD , DERKSEN RICHARD , SREERAM NARAYANSWAMI
Published: July 2003

MOLENSCHOT, M., et al.: Catheter Ablation of Incisional Atrial Tachycardia Using a Novel Mapping System: LocaLisa. Incisional atrial tachycardia occurs due to reentry around surgical scars. Pharmacological therapy is often ineffective. This study assessed the efficacy of a novel mapping system (LocaLisa) in facilitating catheter ablation of incisional atrial tachycardia circuits. Eight consecutive patients (four men, four women) with incisional atrial tachycardia (median age 23.5 years, range 9–44) following previous repair of congenital heart defects underwent transcatheter mapping and ablation of the arrhythmogenic substrate using a mapping system (LocaLisa) that allows localization of endocardial electrodes in a three‐dimensional space. Critical isthmuses for the tachycardia circuits were identified by demonstrating concealed entrainment using standard pacing and mapping techniques. Scars and natural anatomic barriers were marked on the LocaLisa image. Lines of block were created by radiofrequency current application between scars and natural anatomic barriers, or between two scars, to close isthmuses demonstrated to be critical for the reentrant circuit. All lines of block were verified in both directions. All reentrant circuits around incisions were successfully ablated. Seven additional tachycardia mechanisms were identified in four patients (common atrial flutter [n = 4], atrioventricular nodal [AVN] reentry [n = 2], ectopic atrial tachycardia [n = 1]) and were also ablated in a single session. The mean fluoroscopy time was 28.4 ± 13.8 minutes. All patients are arrhythmia‐free at a median follow‐up of 20 (6–22) months. The LocaLisa mapping system is effective for identification of scars and ablation targets, for confirming lines of block, and facilitating ablation of complex reentrant circuits.
Role of Programmed Ventricular Stimulation and Implantable Cardioverter Defibrillators in Patients with Idiopathic Dilated Cardiomyopathy and Syncope
Authors: BRILAKIS EMMANOUIL S. , SHEN WIN K. , HAMMILL STEPHEN C. , HODGE DAVID O. , REA ROBERT F. , LEXVOLD NANCY Y. , FRIEDMAN PAUL A.
Published: July 2003

BRILAKIS, E.S., et al.: Role of Programmed Ventricular Stimulation and Implantable Cardioverter Defibrillators in Patients with Idiopathic Dilated Cardiomyopathy and Syncope. The aim of this study was to evaluate the role of programmed ventricular stimulation and ICDs in patients with idiopathic dilated cardiomyopathy and syncope. Between 1990 and 1998, 54 (mean age 67 ± 11 years, 76% men) patients presented with idiopathic dilated cardiomyopathy and syncope. An electrophysiological study was done in 37 of the 54 patients: 10 had inducible sustained monomorphic ventricular tachycardia, 12 had conduction system disease or neurocardiogenic syncope, and 15 had a normal study. Overall, 17 patients received an ICD, 15 patients received a pacemaker, and 22 patients received no device. Nine of the 15 patients with a negative electrophysiological study eventually received an ICD: 3 because they were considered high risk and 6 because of recurrent syncope or presyncope. In the 17 patients who received an ICD, incidence of appropriate shocks at 1 and 3 years was 47% and 74%, respectively, in the inducible sustained monomorphic ventricular tachycardia group, and 40% and 40%, respectively, in the group without inducible sustained monomorphic ventricular tachycardia (P = 0.29, log‐rank test). In conclusion, programmed ventricular stimulation is not useful in risk stratification of patients with idiopathic dilated cardiomyopathy and syncope and may delay necessary ICD implantation.
Cardiac Rhythm Disturbances in Patients with Left Atrial Isomerism
Authors: WU MEI‐HWAN , WANG JOU‐KOU , LIN JIUNN‐LEE , LAI LING‐PING , LUE HUNG‐CHI , HSIEH FON‐JOU
Published: July 2003

WU, M.‐H., et al.: Cardiac Rhythm Disturbances in Patients with Left Atrial Isomerism. This long‐term study sought to determine the clinical implication of defective sinus node and AV conduction tissue in patients with left atrial isomerism (LAI). From 1984 to 1998, a total of 22 patients were identified as LAI. Patient age at the last follow‐up ranged from 2 to 276 months (90 ± 70 months). Associated cardiac anomalies were interruption of the inferior vena cava (n = 18, 82%), common atrium (n = 9, 41%), AV canal (n = 14, 64%), double‐outlet right ventricle (n = 8, 36%), and pulmonary stenosis (n = 15, 68%). Palliative interventions were performed in 16 patients (Fontan‐type operation in 4 patients, shunt followed by Fontan‐type operation in 2, repair of septal defect in 4, and extracardiac intervention in 6). During the follow‐up, over half of the patients (n = 14, 64%) developed bradyarrhythmia (onset age: from 1 to 264 months; median 78 months): junctional rhythm (n = 11), sinus bradycardia (n= 8) (5 patients also had junctional rhythm), and AV block (n = 2, both also had junctional rhythm). The probability free from bradyarrhythmia was 80% and 46% at the age of 2 and 6 years, respectively. None of the bradyarrhythmias were directly related to open‐heart surgery. Besides, junctional ectopic tachycardia occurred after Fontan‐type operation in three of six patients. In two patients, a Mahaim‐like pathway was identified during the electrophysiological study. The patients with LAI had a high probability of developing bradyarrhythmias due to abnormal sinus node function. Varied AV conduction abnormalities may include compromised AV conduction, junctional ectopic tachycardia after Fontan‐type operation, and an association of Mahaim‐like pathway.
Combipolar Sensing in Dual Chamber Pacing: Is There Still a Need for Bipolar Leads in the Atrium?
Authors: LINDE CECILIA , MARKEWITZ ANDREAS , STRANDBERG HANS , LARSSON BERIT , BINNER LUDWIG , SCHÜLLER HANS
Published: July 2003

LINDE, C., et al.: Combipolar Sensing in Dual Chamber Pacing: Is There Still a Need for Bipolar Leads in the Atrium? Bipolar leads have been shown to provide superior sensing conditions compared to unipolar leads as bipolar sensing is less susceptible to interference. However, the mechanical long‐term integrity and longevity of bipolar leads is inferior to that of unipolar leads. A prospective randomized, multicenter study was performed to investigate a new atrial detection configuration called combipolar sensing. This new sensing concept is designed for the use of conventional unipolar leads in the atrium and the ventricle. While the atrial stimulation is unipolar, atrial sensing is accomplished in a bipolar way using the ventricular lead tip as the indifferent electrode. A modified dual chamber pacemaker provided with this sensing concept was implanted in 26 patients. At predischarge and at the 1‐ and 3‐month follow‐ups no significant differences in atrial sensing thresholds and P wave amplitudes were found between the unipolar and the combipolar sensing configuration at rest or during provocation. Myopotential inhibition could be demonstrated in 22 patients during unipolar sensing at sensitivity settings as “low” as 2 mV. In contrast, during combipolar sensing it could only be demonstrated in one patient once and only at the highest atrial sensitivity of 0.5 mV. Combipolar atrial sensing is feasible under normal conditions and during provocation. Myopotential interference is negligible. Thus, combipolar sensing offers comparable atrial sensing to bipolar without the disadvantages of a bipolar lead.
Experience with a Cosmetic Approach to Device Implantation
Authors: GIUDICI MICHAEL C.
Published: July 2003

GIUDICI, M.C.: Experience with a Cosmetic Approach to Device Implantation. As more young patients are having device implantations, we need to be more concerned with appearance and function. Over a 20‐ month period pacemakers and defibrillators were implanted in 14 women (mean age 49 years) using a two‐incision technique that leaves no visible scars on the chest.
Late Displacement of a Ventricular Pacing Lead After Respiratory Therapy
Authors: ESPLIGUERO RAMON ARROYO , DOMÍNGUEZ JUAN FRANCISCO OTEO , MEJUTO EVARISTO CASTEDO , MIRANDA ISABEL ANTORRENA , ASO JAVIER ORTIGOSA , CAÑAS ALFONSO CAÑAS , ANDRADE MANUEL ARTAZA
Published: July 2003

ARROYO ESPLIGUERO, R., et al. Late Displacement of a Ventricular Pacing Lead After Respiratory Therapy. This article presents a case of displacement of the ventricular electrode of a DDD pacemaker occurring 3 years after implantation following a session of respiratory therapy. The incident provoked the loss of the ventricular pacing and left pectoral stimulation. The different techniques for achieving airway patency that can be used in respiratory therapy of patients with permanent pacemakers are discussed.
Cross‐Stimulation During Lead Impedance Monitoring
Authors: BEAUFORT‐KROL GERTIE C.M. , BINK‐BOELKENS MARGREET TH.E. , NAGELKERKE DIK , VAN GELDER BERRY M.
Published: July 2003

BEAUFORT‐KROL, G.C.M., et al.: Cross‐Stimulation During Lead Impedance Monitoring. At the age of 4 years, a total cavopulmonary connection was performed in a boy with a complex congenital heart defect. On addition, a DDDR pacemaker was implanted for sick sinus syndrome. Atrial and ventricular leads were epicardially placed at the left atrium and left ventricle. At the age of 10 years, a new epicardial ventricular lead was placed because of malfunction of the existing lead. At the same operation the pulse generator was replaced by a Medtronic Kappa DR 731. After replacement, the boy experienced episodes of phrenic nerve stimulation associated with feelings of discomfort. Holter recordings revealed ventricular stimulation from the atrial stimulus for 2 consecutive beats. This phenomenon repeated exactly every 3 hours and was caused by the automatic lead impedance measurement that used a 5‐V, 1‐ms stimulus output.
Implantable Cardioverter Defibrillator T Wave Oversensing Caused by Hyperglycemia
Authors: KRISHEN AJAY , SHEPARD RICHARD K. , LEFFLER JEANINE A. , WOOD MARK A. , ELLENBOGEN KENNETH A.
Published: July 2003

KRISHEN, A., et al.: Implantable Cardioverter Defibrillator T Wave Oversensing Caused by Hyperglycemia. This case report highlights a previously unreported cause of T wave oversensing in a patient with an ICD and recent onset diabetes. Consistent T wave oversensing was observed at elevated serum glucose levels and this finding was reproduced with a glucose challenge. No T wave oversensing was seen during treatment of hyperglycemia. Alterations in serum chemistry may account for intermittent T wave oversensing in patients with ICDs.
Impact of Electrocardiogram Recording Format on QT Interval Measurement and QT Dispersion Assessment
Authors: FABER THOMAS S. , KAUTZNER JOSEF , ZEHENDER MANFRED , CAMM A. JOHN , MALIK MAREK
Published: July 2003

FABER, T.S., et al.: Impact of Electrocardiogram Recording Format on QT Interval Measurement and QT Dispersion Assessment. The aim of this study was to determine the effect of recording conditions on the operator dependent measures of QT dispersion in patients with known and/or suspected repolarization abnormalities. Among several methods for risk stratification, QT dispersion has been suggested as a simple estimate of repolarization abnormalities. In a cohort of high and low risk patients, different components of the repolarization process were assessed in the 12‐lead ECG using three different paper speeds and amplifier gains. To assess measurement error and reproducibility, a straight line was repeatedly measured. The operator error was 0.675 ± 0.02 mm and the repeatability of the measurement error was 31 ± 6%. The QT interval was most frequently measurable in V2–V5. Depending on the lead selected for analysis, the incidence of visible U waves was greatest in the precordial leads with high amplifier gain and low paper speed, strongly affecting QT interval measurement. The timing of the onset of the QRS complex (QRS onset dispersion) or offset of the T wave was strongly dependent on the paper speed. Paper speed, but not amplifier gain, had a significant shortening effect on the measurement of the maximum QT interval. As QT interval measurement in each ECG lead incorporates QRS onset and T wave offset (depending on the number of visible U waves), the dispersion of each of these parameters significantly affected QT dispersion. Thus, QT dispersion appears to reflect merely the presence of more complex repolarization patterns in patients at risk of arrhythmias.
Assessment of Pacemaker Chronotropic Response: Implementation of the Wilkoff Mathematical Model
Authors: FREEDMAN ROGER A. , HOPPER DONALD L. , MAH JENG , HUMMEL JOHN , WILKOFF BRUCE L.
Published: July 2003

FREEDMAN, R.A., et al.: Assessment of Pacemaker Chronotropic Response: Implementation of the Wilkoff Mathematical Model. There are few practical guidelines for proper adjustment of rate responsive pacemaker sensor parameters. This study describes the application of the chronotropic assessment exercise protocol (CAEP) and the Wilkoff model of chronotropic response to assess the adjustment of pacemaker sensor parameters. In 31 patients implanted 1 month previously with a dual sensor pacemaker, pacemaker sensor parameters were adjusted to yield a peak sensor rate of 100 beats/min on a simple 6‐ minute walk (low intensity treadmill exercise [LITE] protocol); the maximum sensor rate was set to the age predicted maximum heart rate (220‐age). The rate response behavior of the pacemaker was then assessed using the slope of metabolic‐chronotropic relation (MCR) during CAEP exercise. After adjustments based on the LITE protocol, CAEP exercise yielded MCR slopes of 0.92 ± 0.25 for the entire study group, which compares well with the predicted normal slope of 1. However, 7 of the 31 patients had sensor MCR slopes during CAEP exercise that were 2 SD or more below expected. To test the sensitivity of this approach to suboptimal pacemaker programming or suboptimal exercise, simulations were performed with the maximum sensor rate programmed below age‐predicted maximum heart rate or with exercise truncated before maximum exertion; with these conditions, MCR slopes were sharply lower for the entire group. The authors conclude that a simple treadmill walk (LITE) allowed for optimum programming of sensor parameters in most patients, but in a minority the chronotropic behavior was underresponsive. Failure to appropriately adjust pacemaker maximum sensor rate or failure to achieve peak exercise sharply limits the accuracy of this methodology.
Noncontact Mapping‐Guided Ablation of Atrial Flutter and Enhanced‐Density Mapping of the Inferior Vena Caval‐Tricuspid Annulus Isthmus
Authors: SCHNEIDER MICHAEL A.E. , NDREPEPA GJIN , ZRENNER BERNHARD , KARCH MARTIN R. , SCHMIEDER SEBASTIAN , DEISENHOFER ISABEL , SCHREIECK JÜRGEN , SCHÖMIG ALBERT , SCHMITT CLAUS
Published: July 2003

SCHNEIDER, M.A.E., et al.: Noncontact Mapping‐Guided Ablation of Atrial Flutter and Enhanced‐Density Mapping of the Inferior Vena Caval‐Tricuspid Annulus Isthmus. Three‐dimensional visualization of cardiac activation has become important in providing further insights into pathophysiological mechanisms of arrhythmias and to increase the efficacy of catheter ablation. The noncontact mapping enables a single beat analysis in a reconstructed geometry of the cardiac chamber. The aim of the study was to describe three‐dimensional activation patterns and inferior vena caval‐tricuspid annulus (IVC‐TA) isthmus conduction characteristics in patients with atrial flutter and the noncontact guidance of the radiofrequency ablation of this arrhythmia. In 34 patients with atrial flutter, the noncontact probe was deployed in the RA. The global three‐dimensional activation and the isthmus conduction (enhanced density mapping) were delineated during ongoing atrial flutter and paced rhythms. Ablation was performed nonfluoroscopically based on reconstructed anatomy and conduction patterns. Noncontact mapping was compared and validated with conventional multielectrode technique. IVC‐TA isthmus ablation was completed successfully in 33 (97%) of 34 patients. In one patient a lower loop reentry around the inferior vena cava was depicted as a mechanism of atrial flutter. In another patient with positive flutter waves in inferior leads, an activation pattern typical of counterclockwise flutter was demonstrated in propagation maps. During a follow‐up of 15.9 ± 5.9 months, two atrial flutter recurrences occurred (5.8%). A gap of the resumed conduction through the IVC‐TA isthmus was delineated as a mechanism of recurrence and ablated with one and three radiofrequency applications. Noncontact mapping allows construction of the global activation patterns in typical and atypical atrial flutter. It enables the nonfluoroscopic guidance of atrial flutter ablation and a comprehensive evaluation of the ablation results.
Empirical Pulmonary Vein Isolation in Patients with Chronic Atrial Fibrillation Using a Three‐Dimensional Nonfluoroscopic Mapping System: Long‐Term Follow‐Up
Authors: KANAGARATNAM LOGAN , TOMASSONI GERY , SCHWEIKERT ROBERT , PAVIA STEPHEN , BASH DIANNA , BEHEIRY SALWA , LESH MICHAEL , NIEBAUER MARK , SALIBA WALID , CHUNG MINA , TCHOU PATRICK , NATALE ANDREA
Published: July 2003

KANAGARATNAM, L., et al.: Empirical Pulmonary Vein Isolation in Patients with Chronic Atrial Fibrillation Using a Three‐Dimensional Nonfluoroscopic Mapping System: Long‐Term Follow‐Up. The purpose of this study was to assess the feasibility and long‐term results of empirical isolation of both superior pulmonary veins in patients with chronic AF. Although localizing and ablating the focal triggers of AF has been proven an effective approach, this strategy is time consuming, often requires multiple procedures, and carries the risk of pulmonary vein stenosis. Whether ostial electrical isolation of the superior pulmonary veins, without initial detailed mapping, is a more efficient approach is not known. The study included 71 consecutive patients who had chronic AF. Using a nonfluoroscopic electroanatomic mapping system, the left and right superior pulmonary veins were ablated circumferentially at the venoatrial junction, with the aim of achieving electrical isolation of the veins. Following ablation, if frequent atrial ectopies were present, mapping and ablation were considered. The patients were periodically followed with 48‐hour Holter and loop recorder monitoring. After the ablation of the right and left superior pulmonary veins 59 (83%) of 71 patients maintained sinus rhythm without premature atrial beats. The remaining 12 patients underwent further mapping and ablation including 5 patients who required isolation of the left inferior pulmonary veins. True electrical isolation could be achieved only in 45 (31%) of the 147 targeted veins. At the latest follow‐up (mean 29 ± 8 months), 80% of the patients with upper vein isolation remained in sinus rhythm off medications, 62% of the patients maintained sinus rhythm on previously ineffective medications, and 17% continued to be in AF. Fourteen (20%) patients developed intermittent episodes of left atrial flutter, and mapping in these patients revealed large electrically silent areas in the left atrium. Empirical isolation of pulmonary veins appeared to be an effective approach to help maintain sinus rhythm in patients with chronic AF. True electrical isolation of the pulmonary veins was associated with a higher likelihood of long‐term success. Left atrial flutter was seen in a significant number of patients at long‐term follow‐up.
The Effect of Variation in the Interval Between Right and Left Ventricular Activation on Paced QRS Duration
Authors: O'COCHLAIN BRENDAN , DELURGIO DAVID , LEON ANGEL , LANGBERG JONATHAN
Published: July 2003

O'COCHLAIN, B., et al.: The Effect of Variation in the Interval Between Right and Left Ventricular Activation on Paced QRS Duration. Pacing of the RV and LV is a promising technique for treating patients with dilated cardiomyopathy and bundle branch block. The salutary effects of biventricular pacing may be due to resynchronization of LV activation. Currently, available biventricular pacemakers and implanted defibrillators produce simultaneous ventricular output pulses. The purpose of the current study was to assess the effects of variation in the timing of RV and LV activation, using the paced QRS duration as a marker of resynchronization. Twenty‐six patients undergoing transvenous biventricular pacemaker implantation were studied. After stable lead positions were achieved, activation of the LV and RV was varied over a range of ± 50 ms and the QRS duration measured on a 12‐lead ECG. Only 6 (23%) of the 26 patients had maximal shortening of the paced QRS with simultaneous activation of the LV and RV. The shortest paced QRS duration was most often produced by an LV to RV interval of – 30 ms (LV activation preceding RV activation). Optimization of LV to RV interval resulted in an additional 13% shortening of the paced QRS compared to simultaneous activation (P < 0.0001). Patients with leads located on the lateral or anterolateral walls of the LV were more likely to benefit from preexcitation of the LV than did patients with leads in the posterior position. Results of this study suggest that the ability to program the LV to RV interval may be useful to optimize the benefit of biventricular pacing.
Histopathological Correlation of Ablation Lesions Guided by Noncontact Mapping in a Patient with Peripartum Cardiomyopathy and Ventricular Tachycardia
Authors: PALMA EUGEN C. , SAXENBERG VICTORIA , VIJAYARAMAN PUGAZHENDHI , FERRICK KEVIN J. , GROSS JAY N. , KIM SOO G. , FISHER JOHN D.
Published: July 2003

PALMA, E.C., et al.: Histopathological Correlation of Ablation Lesions Guided by Noncontact Mapping in a Patient with Peripartum Cardiomyopathy and Ventricular Tachycardia. A patient with peripartum cardiomyopathy developed a nearly incessant nonsustained VT. Guided by a noncontact mapping system, the tachycardia was mapped to the mid‐septum of the right ventricle and ablated. Despite transient success, the tachycardia recurred and the patient subsequently died of multiorgan failure. Histopathological correlation of the ablation site revealed a nontransmural lesion that may have contributed to the failure of the ablation.