bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparison of Left Atrial Size by Two‐Dimensional Transthoracic Echocardiography and Magnetic Endocardial Catheter Mapping
Authors: PATEL VICKAS V. , REN JIAN‐FANG , MARCHLINSKI FRANCIS E.
Published: July 2003

PATEL, V.V., et al.: A Comparison of Left Atrial Size by Two‐Dimensional Transthoracic Echocardiography and Magnetic Endocardial Catheter Mapping. This study sought to validate the accuracy of magnetic electroanatomic mapping (MEAM) for determining cardiac chamber size in a clinically relevant situation. The authors chose to compare LA size measured by MEAM to that assessed by two‐dimensional guided M‐mode echocardiography. The study included 37 patients with drug refractory paroxysmal atrial fibrillation who underwent two‐dimensional echocardiography and a detailed MEAM of the LA. The entire LA was mapped with a mean of 132 ± 50 points with attention to identifying the mitral annulus and posterior wall of the LA. The MEAM measurement of LA size was taken as the distance from the anterior wall of the LA to the posterior wall in a plane parallel to the mitral valve annulus at atrial end‐diastole. LA dimension determined by M‐mode echocardiography was assessed in a plane parallel to the mitral valve annulus in the parasternal long‐axis view during atrial end‐diastole. LA size assessed by M‐mode echocardiography was 41.2 ± 5.0 versus 40.9 ± 4.5 mm as assessed by MEAM, with good correlation (r = 0.87, P < 0.001). Only three patients had a difference in LA size that was > 0.3 cm between the two measurement techniques. Thus, it appears that LA anteroposterior dimension as determined by electroanatomic mapping is similar to that determined by two‐dimensional guided M‐mode echocardiography. MEAM appears to be an accurate method by which LA size can be assessed in patients with drug refractory atrial fibrillation undergoing left atrial ablation procedures.
Rate Dependent Far‐Field R Wave Sensing in an Atrial Tachyarrhythmia Therapy Device
Authors: COLLINS ROBERT F. , HAUGH CONNOR , CASAVANT DAVID , SHETH NIRAV , BROWN LOIS , HOOK BRUCE
Published: July 2003

COLLINS, R.F., et al.: Rate Dependent Far‐Field R Wave Sensing in an Atrial Tachyarrhythmia Therapy Device. A case is reported of far‐field R wave (FFRW) oversensing resulting in inappropriate atrial tachycardia (AT) detection by a dual chamber pacemaker incorporating atrial autoadjusting sensitivity (AAS). FFRW oversensing occurred during periods of functional atrial undersensing (FAU) with PR interval prolongation. Limitations of the pacemaker's ability to reject FFRWs and programming considerations for addressing this unique behavior are discussed.
Magnetocardiographic and Magnetic Resonance Imaging for Noninvasive Localization of Ventricular Arrhythmia Origin in a Model of Nonischemic Cardiomyopathy
Authors: ÅGREN PÄR LENNART , GÖRANSON HÅKAN , JONSSON HANS , BERGFELDT LENNART
Published: July 2003

ÅGREN, P.L., et al.: Magnetocardiographic and Magnetic Resonance Imaging for Noninvasive Localization of Ventricular Arrhythmia Origin in a Model of Nonischemic Cardiomyopathy. Ventricular arrhythmia may in myocardial failure arise as a consequence of remodeling related to hypertrophy and dilatation. In surgically repaired tetralogy of Fallot (TOF), which carries a substantial risk for ventricular arrhythmias and sudden death, the situation is even more complex and several potential arrhythmia mechanisms exist. The authors wanted to test a completely noninvasive localization technique, magnetocardiography (MCG) and magnetic resonance imaging (MRI), to define the origin of ventricular ectopic beats (VEBs) in this model of nonischemic cardiomyopathy. The study included 84 patients with surgically repaired TOF, all 11 subjects with VEBs Lown grade ≥ 2 on a 24‐hour Holter were included. From 37‐channel MCG registrations, the underlying current dipole was computed for the VEBs, and for anatomic correlation MRIs were produced. Eight patients had VEBs of altogether 11 morphologies during the MCG recording. The RVOT was the origin of 6 VEBs, while 4 originated from the RV free wall, and 1 VEB could not be localized. Applying this completely noninvasive technique, it was possible to define different origins of RV ectopies in a complex heart model. Thus, VEBs originated from the RVOT, suggesting a relation to surgical scars and from the nonoperated parts of the RV, supporting that ventricular remodeling might be of equal importance for arrhythmogenesis in this model of cardiomyopathy. This technique can assist in answering the important question of whether there is any difference in prognostic information depending on the origin and related mechanism of VEBs in this and other high risk conditions.
Characterization of a Long Linear Thermolesion in Rabbit Atria by High Density Mapping
Authors: PIOT OLIVIER , ALLESSIE MAURITS A.
Published: July 2003

PIOT, O., et al.: Characterization of a Long Linear Thermolesion in Rabbit Atria by High Density Mapping. A major problem in radiofrequency ablation is to evaluate if linear atrial lesions are transmural and continuous. Characteristics of the atrial electrograms recorded from these lesions might be useful to determine the completeness of linear atrial lesions. In seven isolated perfused rabbit atria, a long transmural linear lesion was made with a hot needle (perfused with water of 80°C) (width 2 ± 0.2 mm). The lesion extended from the orifice of the superior caval vein to the AV ring. High density mapping (240 electrodes, 7.5 × 7.5 mm) of the right atrium was performed before and after the lesion. Complete bidirectional conduction block was confirmed by pacing close at either side of the lesion. No change in conduction or electrogram characteristics occurred outside the lesion. From the center of the lesion, low amplitude double potentials were recorded. The conduction delay around the lesion and the width of the double potentials showed a high correlation (R2= 0.99) and were both dependent of the site of pacing. From the boundaries of the lesion towards its center, the amplitude and slope of the unipolar electrograms decreased exponentially by 72 ± 5 and 85 ± 3%. From the decay of these electrotonic potentials a space constant (λof 0.79 ± 0.04 mm) could be calculated for the lesion. Unipolar electrograms recorded from a complete and transmural linear atrial lesion are electrotonic in nature. Their characteristics could be used to evaluate the width and depth of the lesion.
Ventricular Coupling of Electrical and Mechanical Dyssynchronization in Heart Failure Patients
Authors: TOUSSAINT JEAN‐FRANÇOIS , LAVERGNE THOMAS , KERROU KHALDOUN , DE DIEULEVEULT BARBARA , PONCE FELIZARDO , FROISSART MARC , LE HEUZEY JEAN‐YVES , GUIZE LOUIS , PAILLARD MICHEL
Published: July 2003

TOUSSAINT, J‐F., et al.: Ventricular Coupling of Electrical and Mechanical Dyssynchronization in Heart Failure Patients. We studied the relationships of electrical and mechanical synchronization in patients with heart failure (CHF) and various degree of ventricular conduction delays. Ninety‐two CHF patients (60 ± 13 years old, LVEF < 45%), NYHA II‐III‐IV, and 35 age‐matched control subjects were studied with angioscintigraphic phase analysis. We measured ejection fractions (LVEF, RVEF) and calculated the total activation time for the left (TtLV) and right ventricle (TtRV), and the synchronization time between right and left ventricle (TRVLV), and between LV apex and base (Tab). Patients were divided into three groups according to QRS duration: group 1 < 120 ms (n = 28), group 2 < 150 ms (n = 23), group 3 ≥ 150 ms (n = 41). In group 1: LVEF = 31.1 ± 10.9%, RVEF = 30.1 ± 12.6%, TtLV = 204 ± 70 ms, TtRV = 183 ± 61 ms, TRVLV = 7 ± 33 ms, Tab = 29 ± 23 ms. In group 2, these were: 27.8 ± 9.1%, 27.8 ± 8.8%, 227 ± 95 ms, 248 ± 137 ms, 35 ± 42 ms*, and 39 ± 53 ms respectively. In group 3: LVEF = 20.5 ± 9.5%†, RVEF = 28.4 ± 16.1%, TtLV = 304 ± 155 ms†, TtRV = 234 ± 106 ms†, TRVLV = 64 ± 42 ms†, and Tab = 67 ± 48 ms*, all P < 0.001 versus controls *P < 0.05 versus G1, †P ≤ 0.01 versus G1. A significant relation links QRS to both inter‐ and intraventricular asynchrony (TRVLV: r = 0.65; TtLL: r = 0.70, Tab: r = 0.60), and to LV function (r = 0.72); while LVEF relates more closely to intraventricular asynchrony: TtLV (r = 0.52), TtLL (r = 0.67), than to interventricular asynchrony: TRVLV (r = 0.48); P < 0.01, P ≤ 0.001. In CHF patients, electromechanical and contractile alterations are coupled; regional activation may be an early parameter allowing the detection of ventricular dyssynchronization.
Variability of Holter Electrocardiographic Findings in Patients Fulfilling the Noninvasive MADIT Criteria
Authors: SENGES JULIA C. , BECKER RUEDIGER , SCHREINER KIRSTEN D. , BAUER ALEXANDER , WERETKA SLAWOMIR , SIEGLER KARL , KUEBLER WOLFGANG , SCHOELS WOLFGANG
Published: July 2003

SENGES, J.C., et al.: Variability of Holter Electrocardiographic Findings in Patients Fulfilling the Noninvasive MADIT Criteria. In the MADIT study, a selected group of postinfarction patients with asymptomatic nonsustained ventricular tachycardia (NSVT) has been shown to benefit from prophylactic ICD treatment. The present study analyzed the variability of NSVT in a patient population fulfilling the noninvasive MADIT criteria. Three consecutive Holter ECGs were performed in weekly intervals in 68 postinfarction patients with an LVEF ≤ 0.35. Patients with NSVT underwent programmed ventricular stimulation (PVS); patients were implanted with an ICD if sustained VT or VF was inducible. If NSVT was found in at least two recordings, the arrhythmia was defined as reproducible. In 28 (41%) of the 68 patients, NSVT was found in at least one recording. Seventeen patients revealed NSVT in the first, the remaining 11 in the second registration; no patient had NSVT only in the third Holter. Of the patients with NSVT, 50% had only one, 39% had two, and 11% had three positive recordings. Thus, reproducible NSVT was found in only 50% of the patients with NSVT. Predictors for reproducibility were LVEF > 0.27, NYHA Class I, absence of digitalis therapy, and > 2 NSVT per 24‐hour period. Reproducible NSVT was not associated with risk factors such as elevated mean heart rate, reduced heart rate variability, late potentials, or inducibility of sustained VT during PVS. During 17 ± 9 months of follow‐up, seven (10%) patients experienced arrhythmic events: two without and five with previously documented NSVT. In the latter patients, first occurrence of NSVT was consistently in the first Holter; only two of them had reproducible NSVT. In postinfarction patients, the risk factor NSVT exhibits marked spontaneous variability, especially in those with a low number of NSVT per 24‐hour period, LVEF < 0.27 or NYHA III, which limits its clinical value as a selection criterion for PVS. Reproducibility of NSVT itself does not seem to be an independent risk factor.
Pacing in the Middle Cardiac Vein in a Patient with Tricuspid Prosthesis
Authors: NGUYEN LUC S. , SWAROOP SATINDER , PREJEAN CURTIS A.
Published: July 2003

NGUYEN, L.S., et al.: Pacing in the Middle Cardiac Vein in a Patient with Tricuspid Prosthesis. A man with acute endocarditis developed complete heart block several days after the tricuspid and aortic valve replacement. Several weeks after implantation, his epimyocardial pacing leads developed a high threshold and failed to capture the ventricle at the maximal pulse width and output of the pacemaker. An angled‐tip lead was placed in the middle cardiac vein for ventricular pacing. The pacing and sensing thresholds of this lead were within the expected range during follow‐up. Therefore, in patients with prosthetic tricuspid valve, pacing in the middle cardiac vein should be considered before open‐chest placement of the epimyocardial lead.
Reversion and Maintenance of Sinus Rhythm in Patients with Permanent Atrial Fibrillation by Internal Cardioversion Followed by Biatrial Pacing
Authors: FRAGAKIS NIKOLAOS , SHAKESPEARE CARL F. , LLOYD GUY , SIMON RON , BOSTOCK JULIAN , HOLT PHYLLIS , GILL JASWINDER S.
Published: July 2003

FRAGAKIS, N., et al.: Reversion and Maintenance of Sinus Rhythm in Patients with Permanent Atrial Fibrillation by Internal Cardioversion Followed by Biatrial Pacing. Patients in atrial fibrillation (AF) who fail external cardioversion are usually regarded as in permanent AF. Internal cardioversion may revert many such patients into sinus rhythm (SR) but the majority relapse rapidly into AF. We investigated whether internal cardioversion followed by biatrial pacing is an effective to restore and subsequently maintain SR in patients with permanent AF. Patients in permanent AF underwent internal cardioversion that was followed by biatrial temporary pacing for 48 hours. Those who remained in SR received a permanent biatrial pacemaker programmed to a rate responsive mode with a lower rate 90 beats/min. Primary end point of the study included maintenance in SR 3 months after internal cardioversion. Sixteen patients (14 men, 57 ± 11 years) were cardioverted. The median duration of AF was 24 months (quartiles, Q1= 8.5 and Q3= 102) and mean left atrium diameter was 48 ± 04 mm. A permanent biatrial pacemaker was implanted in 11 patients. At a mean follow‐up of 15 months (range 4 to 24), 8 patients remained in SR for more than 3 months. AF was eliminated in 5 patients, while in two a second internal cardioversion on amiodarone was required. Antiarrhythmic therapy was used in half of our population and did not predict the long‐term maintenance of SR. Following internal cardioversion with continuous biatrial pacing, 50% of patients with permanent AF were maintained for prolonged periods in SR. This is a new modality of treatment of permanent AF directed to the maintenance of SR that provides a further therapeutic option in end‐stage AF.
Rapid Pacing Results in Changes in Atrial But Not in Ventricular Refractoriness
Authors: SCHOONDERWOERD BAS A. , VAN GELDER ISABELLE C. , TIELEMAN ROBERT G. , BEL KLAAS J. , CRIJNS HARRY J.G.M.
Published: July 2003

SCHOONDERWOERD, B.A., et al.: Rapid Pacing Results in Changes in Atrial But Not in Ventricular Refractoriness. It is well known that atrial tachycardia causes atrial electrical remodeling, characterized by shortening of atrial effective refractory periods (AERPs) and loss of physiological adaptation of AERP to rate. However, the nature and time course of changes in ventricular effective refractory periods (VERP) caused by rapid rates are to be established. After being instrumented with epicardial electrodes on both atria and both ventricles nine goats were subjected to 1 week of rapid AV pacing with a rate of 240 beats/min and an AV delay of 100 ms. Pacing was only interrupted for measurement of left and right AERPs and VERPs at three basic cycle lengths (BCL) of 400 ms, 300 ms, and 200 ms during sinus rhythm in the conscious animal. Left and right AERPs decreased at all BCLs, reaching minimum values after 3 days (right AERP at BCL of 400 ms, 96 ± 16 ms after 3 days vs 144 ± 16 ms at baseline, P < 0.05). In contrast, both left and right VERPs did not change at any BCL. This study demonstrates a difference between the atria and ventricles with respect to tachycardia induced changes in refractoriness.
Transient Proarrhythmic State Following Atrioventricular Junctional Radiofrequency Ablation
Authors: NOWINSKI KAROLINA , GADLER FREDRIK , JENSEN‐URSTAD MATS , BERGFELDT LENNART
Published: July 2003

NOWINSKI, K., et al.: Transient Proarrhythmic State Following Atrioventricular Junctional Radiofre‐quency Ablation. This study was designed to prospectively assess ventricular de‐ and repolarization by the QRS, QT, and JT intervals, and their dispersion in the 12‐lead ECG during right ventricular pacing at 60, 70, and 80 beats/min during the first month after AV junctional RF ablation. Previous reports have found early polymorphic ventricular arrhythmia after RF AV junctional ablation. Our hypothesis was that there is a proarrhythmic state following this procedure, which depends on the paced rate and time after ablation. The analysis of the immediate changes was based on 17 patients (10 men) with a mean age of 64 years (SD 14) (range 38–82 years). A 12‐lead ECG was recorded during right ventricular pacing at 60, 70, and 80 beats/min within 24 hours (day 1), between 24 and 48 hours (day 2), and 1 week after ablation (day 7). For analysis of changes beyond 1 week, 13 additional patients with a mean age of 73 years (SD 8) (range 62–90 years) were analyzed on days 1, 7, and 30. All intervals were measured with a digitizing table. The mean QRS duration shortened by 2.4% at 60 beats/min (P < 0.01), and the mean QT and JT intervals shortened by 5–7% between days 1 and 7 (P < 0.001). The mean QT was 9% shorter and the mean JT interval was 13% shorter at 80 compared to 60 beats/min on day 1 (P < 0.001). QT dispersion was reduced by 13% when the stimulation rate was increased from 60 to 80 beats/min on day 1 (P < 0.05). There were no significant changes beyond the first week. The study results point to the induction of a proarrhythmic state immediately after AV junctional RF ablation resolving during the first week. Repolarization shortened gradually between 80 and 60 beats/min to an extent that is suggestive of a clinically important antiarrhythmic effect at the higher rate, which was supported also by clinical experience.
Detection of Rapid Changes in Ventricular Refractoriness in Human Studies
Authors: TOIVONEN LAURI , KETTUNEN EIJA , SIMELIUS KIM , PARIKKA HANNU
Published: July 2003

TOIVONEN, L., et al.: Detection of Rapid Changes in Ventricular Refractoriness in Human Studies. Conventional determination of the ventricular effective refractory period (VERP) is unsuitable for detection of rapid fluctuations in the effective refractory period (ERP). A programmed stimulation system was developed that adapts continuous atrioventricular sequential pacing, incremental extrastimulus interval (S1S2) scanning, and automatic detection of extrastimulus capture which is followed by shortening of S1S2 to execute repeated scanning. The accuracy of ERP determination was tested using variable incremental (2 and 4 ms) and decremental (4–16 ms) steps of the S1S2 interval. Based on a mean of 82 determinations in eight patients, the average VERP values stayed at 249.8–251.0 ms except during the highest capture frequency. Standard deviation of ERP values ranged from 1.1 to 2.5 ms on average at the tested incremental and decremental steps. One determination was accomplished within 7.8–15.6 seconds on average. The ability to track changes in ERP was tested by changing the drive cycle length. Time constants for the adaptation rate of VERP and ventricular monophasic action potential duration at a 90% level of repolarization were determined from each test, and were similar, 51 ± 8 seconds (mean ± SEM) for ERP and 51 ± 6 seconds for the action potential duration. Thus, the developed method provides accurate ERP measurements during rapid variation in ventricular refractoriness. It allows studying the recovery of excitability and the action potential duration simultaneously, and would be valuable particularly in pathological conditions and pharmacologic interventions where these electrophysiological variables become dissociated.
Progressive Isthmus Delay During Atrial Flutter Ablation: The Critical Importance of Isthmus Spanning Electrodes for Distinguishing Pseudoblock from Block
Authors: FRIEDMAN PAUL A. , LURIA DAVID , MUNGER THOMAS M. , JAHANGIR ARSHAD , SHEN WIN K. , REA ROBERT F. , GRICE SUELLEN , ASIRVATHAM SAMUEL , PACKER DOUGLAS L. , HAMMILL STEPHEN C.
Published: July 2003

FRIEDMAN, P.A., et al.: Progressive Isthmus Delay During Atrial Flutter Ablation: The Critical Impor‐tance of Isthmus Spanning Electrodes for Distinguishing Pseudoblock from Block. Bidirectional isthmus block is associated with successful atrial flutter ablation, whereas creation of increased isthmus conduction delay without block can be proarrhythmic. Often, halo catheter electrodes fail to provide adequate sub‐Eustachian isthmus recordings. The aim of this study was to determine if progressive isthmus conduction delay results in the false appearance of block during atrial flutter ablation. A 20‐pole deflectable catheter was prospectively positioned across the sub‐Eustachian isthmus (from the coronary sinus os [CSO] to 7:00 on the tricuspid valve annulus [TVA] clock face in the left anterior oblique [LAO] projection) in nine patients undergoing atrial flutter ablation. During sinus rhythm, conduction time was measured from the CSO to the 7:00 position while pacing the CSO. Measurements were repeated after each linear lesion and after conduction block was achieved. Transisthmus conduction time at baseline, just prior to success, and after the presence of complete block was 54 ± 9, 123 ± 39, and 155 ± 30 ms, respectively (P ≤0.01). The marked delay prior to complete block resulted in reversal of the activation sequence in electrodes at TVA 7:00, creating the false appearance of isthmus block; the isthmus electrodes clearly distinguished delay from block. Catheter ablation results in progressive isthmus conduction delay prior to the creation of complete block. Electrodes spanning the isthmus and line of block are critical for distinguishing conduction delay (and pseudoisthmus block) from block.
Feasibility Study of Real‐Time Three‐Dimensional Intracardiac Echocardiography for Guidance of Interventional Electrophysiology
Authors: SMITH STEPHEN W. , LIGHT EDWARD D. , IDRISS SALIM F. , WOLF PATRICK D.
Published: July 2003

SMITH, S.W., et al.: Feasibility Study of Real‐Time Three‐Dimensional Intracardiac Echocardiography for Guidance of Interventional Electrophysiology. The authors tested the feasibility of real‐time three‐dimensional intracardiac echocardiography for guidance of interventional electrophysiological studies. The three‐dimensional scanner uses a matrix array ultrasound transducer of 64 channels operating at 5 MHz in a 12 Fr catheter. The system features real‐time three‐dimensional image rendering and produces up to 60 volumetric scans per second. Using an open‐chest sheep model, real‐time three‐dimensional images of anatomic landmarks were obtained, including the pulmonary veins and coronary sinus, which are of value in electrophysiological procedures. In vivo radio frequency ablation procedures in the right ventricle were also monitored, which yielded lesions of high image contrast.
Signal‐Averaged Electrocardiographic Parameter Progression as a Marker of Increased Electrical Instability in Two Cases with an Overt Form of Arrhythmogenic Right Ventricular Cardiomyopathy
Authors: BAUCE BARBARA , BASSO CRISTINA , NAVA ANDREA
Published: July 2003

BAUCE, B., et al.: Signal‐Averaged Electrocardiographic Parameter Progression as a Marker of In‐creased Electrical Instability in Two Cases with an Overt Form of Arrhythmogenic Right Ventricular Cardiomyopathy. In arrhythmogenic right ventricular cardiomyopathy (ARVC) the fibrofatty substitution of the RV myocardium constitutes the substrate for reentrant circuits, leading to the onset of ventricular arrhythmias. This pathological process also accounts for “delayed ventricular potentials” that could be recorded as late potentials using the signal‐averaged ECG technique (SAECG). This study examined two patients affected by overt forms of ARVC who showed a worsening of the electrical instability associated with a fast progression of SAECG parameters, while all the other clinical findings remained unchanged. This suggests a possible role of SAECG parameter progression as a marker of increased electrical instability.
Inhibition of Biventricular Pacemakers by Oversensing of Far‐Field Atrial Depolarization
Authors: LIPCHENCA IGOR , GARRIGUE STÉPHANE , GLIKSON MICHAEL , BAROLD S. SERGE , CLÉMENTY JACQUES
Published: July 2003

LIPCHENCA, I., et al.: Inhibition of Biventricular Pacemakers by Oversensing of Far‐Field Atrial Depo‐larization. This report describes two patients who exhibited far‐field oversensing of the P wave by the ventricular channel of a DDD biventricular pacemaker implanted for the treatment of congestive heart failure. Oversensing probably occurred secondary to slight displacement of the left ventricular lead in the coronary venous system. Long‐term reliable pacing was restored by decreasing the sensitivity of the ventricular channel.
Cerebral Syncope in a Patient with Spinal Cord Injury
Authors: BISHARAT NAIEL , PAZ EHUD , KLIMOV ALEXANDER , FRIEDBERG NAHUM , ELIAS MAZEN
Published: July 2003

BISHARAT, N, et al.: Cerebral Syncope in a Patient with Spinal Cord Injury. An 80‐year‐old patient suffering from traumatic paraplegia due to spinal cord compression was admitted due to recurrent orthostatic syncope. Tilt table testing revealed that the patient lost consciousness without hypotension. Doppler flow measurements of the middle cerebral arteries showed a significant decrease in diastolic velocity during syncope without systemic hypotension. Treatment with β‐blockers was highly effective. The patient suffered from cerebral blood flow disregulation probably due to abnormal baroreceptor responses triggered during orthostatic stress. This is the first reported case of a patient with spinal cord injury suffering from such an unusual cause of syncope.
Phased‐Array Intracardiac Echocardiography for Guiding Transseptal Catheter Placement: Utility and Learning Curve
Authors: JOHNSON SUSAN B. , SEWARD JAMES B. , PACKER DOUGLAS L.
Published: July 2003

JOHNSON, S.B., et al.: Phased‐Array Intracardiac Echocardiography for Guiding Transseptal Catheter Placement: Utility and Learning Curve. The utility of a new intracardiac 64‐element, phased‐array, longitudinal ultrasound imaging system for guiding transseptal catheterization was assessed during 69 crossing attempts in 45 dogs because of the inherent limitations of fluoroscopy and mechanical ultrasound. Multifrequency (7.5–8.5 MHZ) imaging of the membranous fossa ovalis, posterior left atrium, and left atrial appendage was conducted from the right atrium. Contact of the Brockenbrough needle with the interatrial septum as reflected by membranous fossa ovalis “tenting” was uniformly identified. Transseptal crossing and advancement of the dilator and sheath were adequately imaged because of deeper ultrasound tissue penetration. Transseptal catheterization was successfully accomplished in 44 of 45 dogs: on the first attempt in 40 and with additional attempts in 4 and confirmed by direct far‐field imaging of nonagitated saline injection via the sheath. Total transseptal catheterization time was 3.0 ± 1.8 minutes. Unsuccessful first attempts and/or subsequent sheath pullback into the right atrium with catheter manipulation were also readily recognized. Insertion of the transseptal needle beyond the ultrasound imaging plane resulted in perforation of the posterior left atrial wall in three attempts. Accompanying effusions in these animals and three others related to subsequent intracardiac ablation catheter manipulation were readily identified and monitored echocardiographically. In conclusion, phased‐array intracardiac imaging provides a highly reliable means of guiding transseptal access to the left atrium. In addition, inadvertent complications such as perforation and pericardial effusion development can be readily recognized.
Electrophysiological Features of Atrial Tachycardia Arising from the Atrioventricular Annulus
Authors: MATSUOKA KOJI , KASAI ATSUNOBU , FUJII EITARO , OMICHI CHIKAYA , OKUBO SETSUYA , TERAMURA SHINOBU , UCHIDA FUMIYA , NAKANO TAKESHI
Published: July 2003

MATSUOKA, K., et al.: Electrophysiological Features of Atrial Tachycardia Arising from the Atrioven‐tricular Annulus. Atrial tachycardia (AT) arises from various sites in the atrium and the mechanisms are nonuniform. McGuire et al. reported that the cells around the atrioventricular annuli resembled nodal cells in their cellular electrophysiology. The purpose of this study was to delineate the electrophysiological features of AT arising from the atrioventricular (AV) annulus (AVAT). The study included five patients with six AVATs that were abolished by the radiofrequency energy delivery. The location of the AV annuli was defined by using the AV ratio of the local electrograms and the amplitude of the ventricular electrograms, in addition to the anatomic findings under fluoroscopic guidance. The tachycardia cycle lengths were 403 ± 117 ms. An AV ratio of the electrograms at the successful ablation sites was 0.4 ± 0.4 at the tricuspid annulus and 1.5 ± 0.3 at the mitral annulus. Small doses (mean 3.2 ± 1.8 mg) of adenosine triphosphate could terminate all the tachycardia episodes for five of the ATs without the development of AV nodal conduction block. The successful ablation sites were located at the right mid‐septum in 1 AT, right posteroseptum in 2 ATs, right posterolateral region in 1 AT, and left anteroseptum in 2 ATs. These findings suggest that the cells with nodal‐type action potentials around both annuli might play an important role in the genesis of AVAT.
Site of the Arrhythmogenic Focus and Cardiac Vulnerability to Ventricular Fibrillation
Authors: MURAKAWA YUJI , YAMASHITA TAKESHI , AJIKI KOHSUKE , HAYAMI NORIYUKI , FUKUI EI‐ICHI , KASAOKA YUJI , OMATA MASAO , NAGAI RYOZO
Published: July 2003

MURAKAWA, Y., et al.: Site of the Arrhythmogenic Focus and Cardiac Vulnerability to Ventricular Fib‐rillation. The aim of this study was to test the hypothesis that a subendocardial arrhythmogenic focus makes the heart more susceptible to VF due to electrical interaction with the Purkinje network. Monofocal ventricular tachycardia (mVT) was created by injecting 5‐μg aconitine into the left ventricular subepicardium (EPI‐mVT, n = 8) or subendocardium (ENDO‐mVT, n = 13) in anesthetized dogs. Despite the similar cycle length of mVT, the incidence of VF was significantly different between EPI‐mVT and ENDO‐mVT (100 [8/8] vs 46% [6/13], P < 0.05). VF was invariably preceded by hemodynamic deterioration. Three‐dimensional cardiac mapping (n = 10, 221 ± 11 recording sites) revealed that VF was triggered solely by focal firing unrelated to the primary arrhythmogenic focus in both mVT models. No interaction between the primary focus and adjacent endocardial tissue was indicated. These results suggest that the proximity of the arrhythmogenic focus to the Purkinje network has little role in cardiac vulnerability to VF, and that progression of mVT to VF is largely caused by sporadic focal firing regardless of the site of the arrhythmogenic focus in the present animal model.
Adenosine Induced Ventricular Fibrillation in Wolff‐Parkinson‐White Syndrome
Authors: GUPTA ANOOP K. , SHAH CHETAN P. , MAHESHWARI ALOK , THAKUR RANJAN K. , HAYES OLIVER W. , LOKHANDWALA YASH Y.
Published: July 2003

GUPTA, A. K., et al.: Adenosine Induced Ventricular Fibrillation in Wolff‐Parkinson‐White Syndrome. VF was observed in four patients (group A) with preexcited AF presenting to the emergency department who had been given 12 mg of adenosine. These patients were resuscitated and underwent electrophysiological study and catheter ablation of the accessory pathway (AP). In a control (group B) of five patients with manifest AP, sustained AF was induced by rapid atrial pacing during electrophysiological study and 12 mg of adenosine was administered. The ECG and electrophysiologic features in the two groups were compared. All patients had a single manifest AP. In group A, three patients had a left free‐wall AP and one patient had a posteroseptal AP, while in the control group all had left free‐wall APs. The antegrade AP effective refractory period (ERP) in groups A and B was 227 ± 29 and 289 ± 37 ms, respectively (P < 0.05). The atrial ERP was 210 ± 17 versus 219 ± 21 ms, respectively, in groups A and B (P > 0.05). The shortest R‐R interval during AF in group A was 246 ± 51 ms and 301 ± 60 ms in group B (P value < 0.05). After adenosine, no patient in group B developed VF. Adenosine may cause VF when administered during preexcited AF. This phenomenon is seen in patients having APs with short refractory periods.
Assessment of Noise in Digital Electrocardiograms
Authors: BATCHVAROV VELISLAV , HNATKOVA KATERINA , MALIK MAREK
Published: July 2003

BATCHVAROV, V., et al.: Assessment of Noise in Digital Electrocardiograms. Technically related noise in 12‐lead ECGs recorded with ambulatory recorders has never been systematically compared with that in ECGs recorded with conventional ECGs. This study compared serial 10‐second ECGs obtained in ten healthy men, age 22–45 years, who were recorded in the supine resting position using a (1) MAC VU recorder, (2) digital ambulatory SEER MC recorder with a Multi‐Link detachable ECG cable, and (3) digital ambulatory SEER MC recorder with a light ambulatory ECG cable. In each ECG, averaged sinus rhythm cycles of the entire recording were realigned with the native signal and subtracted. The resulting “residuum” was quantified by computing its standard deviation and root mean square of successive differences (RMSSD). While the RMSSD residuum values were significantly lower with the MAC VU recorder (6.27 ± 0.98 μV) than with the SEER MC recorder with either ECG cables (7.29 ± 1.31 and 7.17 ± 1.31 μV, P < 0.003 and p < 0.02), the difference was practically negligible and there was no detectable difference in the standard deviation residuum values. The study concludes that valid ECG investigations of serial ECG testing may be conducted using the ambulatory SEER MC recorders providing the biological sources of ECG noise are controlled. The available technology for noise assessment suggests that studies involving advanced analysis of serial ECGs (e.g., of drug related changes), should incorporate objective characterisation of ECG quality.
Mexiletine Related Chronic Defibrillation Threshold Elevation: Case Report and Review of the Literature
Authors: CRYSTAL EUGENE , OVSYSHCHER I. ELI , WAGSHAL ALAN B. , KATZ AMOS , ILIA REUVEN
Published: July 2003

CRYSTAL, E., et al.: Mexiletine Related Chronic Defibrillation Threshold Elevation: Case Report and Review of the Literature. Many antiarrhythmic drugs may produce a rise in defibrillation threshold. Mexiletine is a frequently used antiarrhythmic drug in patients with an implantable cardioverter defibrillator, usually thought of as producing no or minimal effects on the defibrillation threshold. The current case report presents a patient with an endocardial implantable cardioverter defibrillator being treated with mexiletine, which precluded the ability to defibrillate the patient.
Comparison of the Performance of Three Diagnostic Algorithms for Regular Broad Complex Tachycardia in Practical Application
Authors: LAU ERNEST W. , NG G. ANDRÉ
Published: July 2003

LAU, E.W., et al.: Comparison of the Performance of Three Diagnostic Algorithms for Regular Broad Complex Tachycardia in Practical Application. The authors previously proposed a Bayesian approach to the electrocardiographic diagnosis of regular broad complex tachycardia (BCT), which can be due to VT or supraventricular tachycardia with aberrant conduction (SVTAC). They also published an account comparing the theoretical merits in the design of two of the most commonly used diagnostic algorithms for the same purpose, those of Brugada et al. and Griffith et al. In this study, a direct head‐to‐head comparison was performed on the practical performances of the three algorithms in this study. A set of 111 ECGs showing regular BCT (77 VT, 34 SVTAC) whose diagnoses were confirmed by electrophysiological study was shown to five internists in general medicine at a district general hospital. The observers were asked to comment on whether the ECG criteria in the three algorithms tested were fulfilled or not, and a computer program then derived the corresponding diagnoses. The sensitivity and specificity for VT achieved by the Brugada algorithm were 92% and 44%, 92% and 44% by the Griffith algorithm, and 97% and 56% by the Bayesian algorithm. The Bayesian algorithm achieved a higher sensitivity and specificity than the other two algorithms, but the differences are not statistically significant (P = 0.6583 and P = 0.5334, respectively). The Brugada, Griffith, and Bayesian algorithms show comparable performances in terms of overall sensitivity and specificity when tested in practice. Of the three algorithms, the Griffith algorithm excels in simplicity and is the easiest to implement in practice. The Bayesian algorithm achieved slightly higher values for sensitivity and specificity than the Brugada and Griffith algorithms but may be more suitable for automated computer‐aided diagnosis of ECG due to its complexity.
Can Radiofrequency Current Isthmus Ablation Damage the Right Coronary Artery? Histopathological Findings Following the Use of a Long (8 mm) Tip Electrode
Authors: WEISS CHRISTIAN , BECKER JAN , HOFFMANN MATTHIAS , WILLEMS STEPHAN
Published: July 2003

WEISS, C., et al.: Can Radiofrequency Current Isthmus Ablation Damage the Right Coronary Artery? Histopathological Findings Following the Use of a Long (8 mm) Tip Electrode. This report describes the histopathological findings following successful RF isthmus ablation for common atrial flutter in a 68‐years‐old man using a long 8‐mm tip ablation catheter. No acute complication was observed. The patient died 3 weeks after ablation due to severe heart failure and consecutive pneumonia. Lesion width (1.0 and 2.4 cm) and depth (0.4 and 0.8 cm) was measured. The right coronary artery showed an intramural hemorrhage adjacent to the side of the lesion. However, despite this finding no apparent injury of other layers of the coronary artery was detectable.
Documentation of Acute Rise in Ventricular Capture Thresholds Associated with Flecainide Acetate
Authors: FORNIELES‐PÉREZ HELIO , MONTOYA‐GARCÍA MATILDE , LEVINE PAUL A. , SANZ OSCAR
Published: July 2003

FORNIELES‐PÉREZ, H., et al.: Documentation of Acute Rise in Ventricular Capture Thresholds Associated with Flecainide Acetate. Treatment of paroxysmal atrial fibrillation with flecainide acetate resulted in a 4‐fold increase in ventricular capture thresholds. The detailed time course of the threshold increase and decrease was documented using the AutoCapture algorithm and graphic summary.
Can Current Minute Ventilation Rate Adaptive Pacemakers Provide Appropriate Chronotropic Response in Pediatric Patients?
Authors: CABRERA MARCO E. , PORTZLINE GERRY , AACH SUSAN , CONDIE CATHY , DOROSTKAR PARVIN , MIANULLI MARCUS
Published: July 2003

CABRERA, M.E., et al.: Can Current Minute Ventilation Rate Adaptive Pacemakers Provide Appropriate Chronotropic Response in Pediatric Patients? Since children have different activity patterns and exercise responses, uncertainty exists as to whether minute ventilation (MV) sensors designed for adults provide adequate chronotropic response in pediatrics. In particular, high respiratory rates (RR > 48 breaths/min), which are characteristic of the ventilatory response to exercise in children, cannot be sensed by MV rate responsive pacemakers. The purpose of this study was to evaluate the MV sensor rate response of the Medtronic Kappa 400 using exercise data from healthy children in a computer simulation of its rate response algorithm. Thirty‐eight healthy children, ages 6–14, underwent a treadmill maximal exercise test. Subjects were divided based on body surface area (BSA) and MV rate response parameters were selected. Respiratory rates and tidal volumes were entered into the Kappa 400 rate response algorithm to calculate sensor‐driven rates. Intrinsic heart rate (HR), oxygen uptake, and sensor‐driven rates were normalized to HR reserve (HRR), metabolic reserve (MR), and sensor‐driven reserve to compare across groups. Linear regression analysis among sensor‐driven rate reserve, HRR, and MR was performed as described by Wilkoff. The mean slopes (± SD) of the relationships between the sensor‐driven rate reserve and HRR were 1.06 ± 0.34, 1.07 ± 0.28, and 1.01 ± 0.19 for children with BSA < 1.10 m2, 1.10 < BSA < 1.40 m2, and BSA > 1.40 m2, respectively. High correlations were found between sensor‐drive rates and HR responses and between sensor‐drive rates and MV throughout exercise. No significant differences were noted between sensor‐drive rates and HR using the Wilkoff model. From this study the authors conclude that: (1) MV is a good physiological parameter to control heart rate and (2) simulated sensor‐driven rates closely match intrinsic HRs during exercise in healthy children, which supports the appropriateness of clinical validation in pediatric pacemaker patients.
The Morphology of the Specialized Atrioventricular Junctional Area: The Evolution of Understanding
Authors: ANDERSON ROBERT H. , YEN HO SIEW
Published: July 2003

ANDERSON, R.H., et al.: The Morphology of the Specialized Atrioventricular Junctional Area: The Evolution of Understanding. Although knowledge of its existence has barely exceeded one century, the anatomic pathway for conduction of the cardiac impulse from atria to ventricles has been the source of much controversy, controversy that continues to the present day. This article describes how attention to the original descriptions, along with adherence for sensible definitions for the histological distinction of conduction tissues, could have defused many of these disagreements. One of the problems with the initial descriptions was that they were written in German. Even this is no longer a problem, since the major text devoted to the topic has recently been translated into English, and is now available for all to study. This key work was the monograph produced by Sunao Tawara, a Japanese pathologist who studied in the first decade of the 20th century in the laboratory of Ludwig Aschoff. Tawara showed that the atrial impulse was conducted to the ventricular myocardium by a solitary pathway of specialized myocardium. He likened this pathway to a tree, with its roots in the base of the atrial septum, and its branches straddling the crest of the muscular ventricular septum. Significantly, he showed that the pathway became insulated as it crossed from atrial to ventricular musculatures, and suggested that the point at which the muscle became engulfed in fibrous tissue should be taken as the boundary between the “knoten,” or atrioventricular node, and the penetrating bundle described earlier by Wilhelm His. The authors' findings are entirely compatible with the account given by Tawara. Like Tawara, they recognize atrial transitional cells, a compact node, the penetrating bundle, and the ventricular conduction pathways as the segments of the conduction axis which can be considered to represent the specialized atrioventricular junction.
Robotically Enhanced Placement of Left Ventricular Epicardial Electrodes During Implantation of a Biventricular Implantable Cardioverter Defibrillator System
Authors: KLEINE PETER , GRÖNEFELD GERIAN , DOGAN SELAMI , HOHNLOSER STEFAN H. , MORITZ ANTON , WIMMER‐GREINECKER GERHARD
Published: July 2003

KLEINE, P., et al.: Robotically Enhanced Placement of Left Ventricular Epicardial Electrodes During Implantation of a Biventricular Implantable Cardioverter Defibrillator System. Biventricular pacing has gained increasing acceptance in advanced heart failure patients. One major limitation of this therapy is positioning the left ventricular stimulation lead via the coronary sinus. This report demonstrates the feasibility of totally endoscopic direct placement of an epicardial stimulation lead on the left ventricle using the daVinci surgical system.
Loss of Left Ventricular Epicardial Lead Capture Due to Pneumothorax
Authors: BLOMMAERT DOMINIQUE , DEPREZ FRÉDÉRIC , EUCHER PHILIPPE , MANCINI ISABELLE , MUCUMBITSI JOSEPH , COLLET BENOÎT , DE ROY LUC
Published: July 2003

BLOMMAERT, D., et al.: Loss of Left Ventricular Epicardial Lead Capture Due to Pneumothorax. Pneumothorax is a rare complication of pacemaker lead insertion by subclavian way. We report a case of temporary ineffective biventricular pacing due to pneumothorax. This complication has to be ruled out before electing to reposition or to replace the lead.
European Clinical Experience with a Dual Chamber Single Pass Sensing and Pacing Defibrillation Lead
Authors: GRADAUS RAINER , GONSKA BERND D. , STELLBRINK CHRISTOPH , CRON THOMAS , TEBBENJOHANNS JÜRGEN , BLOMSTRÖM‐LUNDQVIST CARINA , HIMMRICH EWALD , SALERNO JORGE A. , OSSWALD STEFAN , GOMMER ERIK D. , VAN VEEN BENNO K. , BÖCKER DIRK
Published: July 2003

GRADAUS, R., et al.: European Clinical Experience with a Dual Chamber Single Pass Sensing and Pacing Defibrillation Lead. Dual chamber ICDs are increasingly implanted nowadays, mainly to improve discrimination between supraventricular and ventricular arrhythmias but also to maintain AV synchrony in patients with bradycardia. The aim of this study was to investigate a new single pass right ventricular defibrillation lead capable of true bipolar sensing and pacing in the right atrium and integrated bipolar sensing and pacing in the right ventricle. The performance of the lead was evaluated in 57 patients (age 61 ± 12 years; New York Heart Association 1.9 ± 0.6, left ventricular ejection fraction 0.38 ± 0.15) at implant, at prehospital discharge, and during a 1‐year follow‐up. Sensing and pacing behavior of the lead was evaluated in six different body positions. In four patients, no stable position of the atrial electrode could intraoperatively be found. The intraoperative atrial sensing was 2.3 ± 1.6 mV and the atrial pacing threshold 0.8 ± 0.5 V at 0.5 ms. At follow‐up, the atrial sensing ranged from 1.5 mV to 2.2 mV and the atrial pacing threshold product from 0.8 to 1.7 V/ms. In 11 patients, an intermittent atrial sensing problem and in 24 patients an atrial pacing dysfunction were observed in at least one body position. In 565 episodes, a sensitivity of 100% and a specificity of 96.5% were found for ventricular arrhythmias. In conclusion, this single pass defibrillation lead performed well as a VDD lead and for dual chamber arrhythmia discrimination. However, loss of atrial capture in 45% of patients preclude its use in patients depending on atrial pacing.
Internal Defibrillation: Pain Perception of Low Energy Shocks
Authors: STEINHAUS DAVID M. , CARDINAL DEBBIE S. , MONGEON LUC , MUSLEY SHAILESH KUMAR , FOLEY LAURA , CORRIGAN SUSIE
Published: July 2003

STEINHAUS, D.M., et al.: Internal Defibrillation: Pain Perception of Low Energy Shocks. Recently, device‐based low energy cardoversion shocks have been used as therapy for AF. However, discomfort from internal low energy electrical shocks is poorly understood. The aim of this study was to evaluate pain perception with low energy internal discharges. Eighteen patients with ICD devices for malignant ventricular arrhythmias were recruited to receive shocks of 0.4 and 2 J in the nonsedated state. Discharges were delivered in a blinded, random order and questionnaires were used to determine discomfort levels and tolerability. Patients perceived discharges at these energies as relatively uncomfortable, averaging a score of 7.3 on a discomfort scale of 0–10, and could not distinguish 0.4‐J shocks from 2‐J shocks. Second shocks were perceived as more uncomfortable than initial discharges, regardless of the order in which the shocks were delivered. Despite the perceived discomfort, 83% of patients stated that they would tolerate discharges of this magnitude once per month, and 44% would tolerate weekly discharges. Patients perceive low energy discharges as painful and cannot distinguish between shocks of 0.4 and 2 J. The results suggest that ICD systems developed to treat atrial tachyarrhythmias should minimize the number of shocks delivered to terminate an atrial tachyarrhythmia episode. The majority of the patients tolerated low energy shocks provided the discharges are infrequent (once per month).