bluuebunny/crossref_metadata_2025 huggingface dataset:
Transesophageal Measurement of Left Atrial Refractoriness
Authors: SIMONCELLI UMBERTO , MARCHETTI ALESSANDRA , SORGATO ALBERICO , FAGGIANO POMPILIO , ONEGLIA CARLO , RUSCONI CESARE
Published: July 2006

During electrophysiological evaluation of supraventricular arrhythmias the transesophageal (TEEP) approach may be the first step but is limited in information available. One difficulty is in measuring left atrial refractoriness as left atrial capture is seldom defectable either on ECG or via an esophageal lead. The problem may be eliminated and left atrial refractoriness measured via the esophagus, utilizing two or three extrastimuli to scan diastole to determine whether the atrial refractory period has been entered by the first extrastimulus. Measurement of left atrial and/or atrioventricular node or accessory pathway refractoriness then becomes possible.
Comparison of Epicardial and Endocardial Programmed Stimulation in Patients at Risk for Ventricular Arrhythmias After Cardiac Surgery
Authors: SHEPPARD ROBERT C. , NYDEGGER CHARLES C. , KUTALEK STEVEN P. , HESSEN SCOTT E.
Published: July 2006

Programmed ventricular stimulation was performed on 36 patients after recent cardiac surgery using implanted right ventricular epicardial temporary wires and with catheters positioned percutaneously at two right ventricular endocardial sites. Patients were followed for a mean of 18.5 months (range 3 to 36 months). Epicardial wires were nonfunctional in 10 patients (28%) due to excessively high pacing thresholds. Overall, 22 patients (61%) had inducible sustained ventricular tachycardia; epicardial wires were functional in 15 (68%) of these patients. Six patients without inducible ventricular tachycardia with epicardial stimulation were inducible using endocardial stimulation. Of the 24 patients in whom epicardial and endocardial ventricular stimulation could be performed, concordant results were obtained in only 17 (71%), despite similar epicardial and endocardial ventricular effective and functional refractory periods. A total of 14 arrhythmic events occurred during the follow‐up period. Of the 22 patients with an inducible sustained ventricular tachycardia, 12 (64%) had subsequent arrhythmic events. Only 2 of the 14 noninducible patients had follow‐up arrhythmic events, one of which was caused by medication proarrhythmia. Endocardial ventricular stimulation had a superior sensitivity (83% versus 30%, P < 0.0001) and an improved negative predictive value (86% versus 61%, P < 0.05) compared with epicardial ventricular stimulation. These results indicate that noninducibility using epicardial programmed ventricular stimulation does not reliably portend a low risk for recurrent ventricular tachyarrhythmias. Epicardial programmed stimulation, used alone, may be inadequate for postoperative electrophysiological evaluation of patients at risk for ventricular arrhythmias.
Electrophysiological Evaluation of Moricizine in Patients with Sustained Ventricular Tachyarrhythmias: Low Efficacy and High Incidence of Proarrhythmia
Authors: BHANDARI ANIL K. , LERMAN ROBERT , EHRLICH STEVEN , SAGER PHILIP , LEON CHERYL , WIDERHORN JOSEPH , CANNOM DAVID S.
Published: July 2006

In patients with history of sustained ventricuiar tachyarrhythmias, the efficacy and safety of moricizine have not been systematically evaluated by electrophysiological studies. We performed electrophysiological testing in these patients in the drug‐free state and then after moricizine loading, and evaluated the safety profile of moricizine during in‐hospital loading and follow‐up. The study population comprised of 31 patients with clinically sustained ventricular tachyarrhythmia. The underlying heart disease was coronary in 25 patients, cardiomyopathy in 5 patients, and none in 1 patient. The left ventricular (LV) ejection fraction ranged from 15%‐69% (mean 39 ± 15%). During the baseline drug‐free electrophysiological testing, sustained ventricular tachycardia was inducibie in 27 patients, ventricuiar fibrillation in 1 patient, and reproducible, nonsustained ventricular tachycardia (15–25 sec) in 3 patients. All 31 patients received moricizine to the maximum tolerated dose (851 ± 185 mg) over a period of 2–7 days. Six patients developed ventricular proarrhythmia within the first 4 days. Proarrhythmia required multiple cardioversions in three patients, was not associated with QT prolongation, and spontaneously resolved 6–24 hours after withdrawal of moricizine. Of the remaining 25 patients, 24 underwent electrophysiological testing on moricizine and 4 patients (16%) were rendered noninducible. The VT cycle length in the other 20 patients slowed from 243 ± 30 msec to 299 ± 60 msec (P < 0.09). Four noninducibie patients, two patients with inducible but slowed VTand one patient who had refused further testing were discharged on moricizine. Among these seven patients, recurrent arrhythmic events occurred in two patients, ventricular proarrhythmia in one patient, complete AV block in one patient, and severe disabling headache in one patient. Only two patients have continued to take moricizine without side effects or recurrent arrhythmic events during a follow‐up of 4 months and 9 months, respectively. Moricizine is only rarely effective for long‐term treatment of patients with spontaneous sustained ventricular tachyarrhythmias, It renders ventricular tachyarrhythmias noninducible in a small minority (16%) and is associated with a high incidence (23%) of ventricular proarrhythmias.
Antibody Mediated Complete Congenital Heart Block in the Fetus
Authors: OLAH KARL S.J. , GEE HARRY
Published: July 2006

Complete congenital heart block (CCHB) affects 1:20,000–25,000 live births and is usually an atrioventricular block; 30–50% of fetuses with CCHB will have a structural anomaly, though recently attention has focused on the etiological influence of autoimmune disease, such as systemic lupus erythematosus. The diagnosis is established by detailed two‐dimensional ultrasound scanning of the heart to exclude anomaly coupled with M‐mode echocardiography and Doppler blood velocity patterns in the major vessels to detect the uncoupling of atrial and ventricular rhythms. Risk factors for an affected child are discussed. A previously affected child, high titers of anti‐Ro antibodies, the presence of anti‐Ro (SS‐A) and anti‐La (SS‐B), and maternal HLA DR3 confer high risk. Antibody mediated CCHB is irreversible. Plasmapheresis and immunosuppression have been attempted in affected mothers, with limited success, to reduce the likelihood of the fetus being affected, and steroids have been used to reduce the inflammatory reaction in the heart. In many cases the underlying pathology of the immune system adversely affects utero‐placental function requiring careful monitoring of fetal well‐being. CCHB renders fetal heart rate monitoring virtually useless, in the antenatal and intrapartum periods. Alternatives are explored.
Unusual Electrocardiographic Findings Associated with Type A Wolff‐Parkinson‐White Syndrome
Authors: KUGA KEISUKE , YAMAGUCHI IWAO , YOSHIZAWA KAZUO , KURUSU TAKEO , TOGO TOSHIHITO , SUGISHITA YASURO
Published: July 2006

A 50‐year‐old woman with Wolff‐Parkinson‐White (WPW) syndrome presented with unusual electrocardiographic (ECG) findings following the termination of paroxysmal supraventricular tachycardia. The ECG showed three different QRS complexes and irregular R‐R intervals. These QRS complexes consisted of: (1) narrow QRS; (2) wide QRS with delta wave; and (3) wide QRS with left bundle branch block (LBBB). The mechanisms of these findings, revealed by electrophysiological study, were: (1) intermittent anterograde left‐sided accessory pathway conduction; (2) rate‐dependent ipsilateral LBBB; and (3) intermittent retrogradely conducted atrial echoes that occurred due to intraventricular conduction delay resulting from LBBR. Cases of WPW syndrome with these unusual ECG findings, which were clearly interpreted by electrophysiological study, are rare.
Clinical Experience with a New DDD External Pacemaker
Authors: KRATZ JOHN , TYLER JIM
Published: July 2006

A multicenter trial of a new external DDD pacemaker was conducted to evaluate its clinical performance. Additionally, methods of temporary lead implantation were analyzed for best performance. The device was found to function with few complications. In only 16 of the 146 devices used was the DDD mode abandoned. Of these, 3 were changed to the AAI mode and 4 were for atrial fibrillation. Several methods of lead implantation proved satisfactory. However, a simple U stitch through the muscle functioned best for atrial application and either a U stitch or a tined stitch functioned best for ventricular application.
Classification of Death in Patients Under Antiarrhythmic Treatment
Authors: ECTOR HUGO , ROGERS RALPH , RUBENS ANN , De GEEST HILAIRE
Published: July 2006

In the evaluation of antiarrhythmic treatment, total motality and total cardiac mortality are the only endpoints difficult to misclassify. End‐stage cardiac failure competes with “suddenness” in many instances of sudden arrhythmic death. This observational study reports on 23 deaths in a group of 129 patients under antiarrhythmic treatment. In the 21 cases of cardiac death, with respect to the notion “sudden arrhythmic death,” classification was problematic in 6 patients. According to different interpretations, the number of deaths listed as “sudden” could vary between one and six. A concise description of cause and circumstances of death, is presented.
Detection of Ventricular Tachycardia and Fibrillation Using Coronary Sinus Blood Temperature: A Feasibility Study
Authors: HILES MICHAEL C. , BOURLAND JOE D. , WESSALE JERRY L. , GEDDES LESLIE A. , VOORHEES WILLIAM D.
Published: July 2006

This study investigated the potential of coronary sinus blood temperature to detect ventricular arrhythmias. A rapid‐response, thermistor‐tipped catheter placed in the coronary venous system of anesthetized dogs was used to record the blood temperature during periods of induced bradycardia, tachycardia, and ventricular fibrillation. A second catheter was used to measure blood temperature in the aortic arch during these same episodes. A pulsatile component of venous blood temperature, typically 40 m°C in amplitude, was well correlated with the cardiac cycle, while another, slightly larger, pulsatile component was well correlated with respiration. The cardiac component peaked during ventricular systole, and the respiratory component peaked during expiration. As compared with sinus rhythm, the cardiac signal diminished during hradycardia and tachycardia and nearly disappeared during asystole and ventricular fibrillation. The baseline component of venous blood temperature rose during periods of tachycardia and fibrillation, while respiration proved to be an important factor in the baseline temperatures. The presence of small, cyclic, thermal variations in the coronary venous system was verified, and the concept of measuring metabolic activity to assess ventricular function was substantiated. These studies show promise that this concept could be incorporated into medical devices that use these temperature signals for diagnosis of ventricular arrhythmias.
Alternating Wenckebach Periods and Allied Arrhythmias
Authors: CASTELLANOS AGUSTIN , INTERIAN ALBERTO , COX MARILYN M. , MYERBURG ROBERT J.
Published: July 2006

Alternating Wenckebach periods (AWPs)are episodes of 2:1 block during which Ihe PR, AH, or AV intervals of the conducted beats gradually increase until a greater degree of block ensues. Most episodes occur at the AVnode, but some have aiso been reported in other structures. AWPs are usually attributed to multilevel block due to transverse (horizontal)dissociation. This assumption was initially based on a method in which the solutions to difficult electrocardiographic rhythms were arrived at by analysis and deduction based on the knowledge existing at that particular time. Subsequently, it was reinforced by information extrapolated from intracardiac recordings performed in patients with documented multilevel block in separate anatomical structures (atria, AV node, and His bundle), as well as from microelectrode studies and computer simulations. Although AWPs are frequently observed in clinical tracings, those occurring at the AV node are best categorized during incremental atrial stimulation because then they occupy a specific point in the wide spectrum of tachycardia dependent AV nodal conduction disturbances. In fact, the A:H ratios occurring in the episodes where the degree of block increases can be represented by “universal” mathematical formulas. However, in the clinical setting, drugs affecting the electrophysiology of the node can alter the pacing induced symmetry by producing additional differential effects on the various levels. The latter still requires further elucidation.
Arteriovenous Fistula: A Complication of Cardiac Pacemaker Lead Placement and Its Management with Percutaneous Embolization
Authors: KIM HENRY Y. , HEYWOOD J. THOMAS , JACOBSON ALAN K. , SMITH DOUGLAS C.
Published: July 2006

A right infernal mammary artery to right brachiocephalic vein fistula was discovered following implantation of a permanent cardiac pacemaker. The fistula was closed via percutaneous embolization.
Surgical Removal of Infected Transvenous Pacemaker Leads
Authors: FRAME ROSEMARY , BRODMAN RICHARD F. , EURMAN SEYMOUR , ANDREWS CAROLYN A. , GROSS JAY N.
Published: July 2006

Infection, though uncommon, can be the most lethal of all potential complications following transvenous pacemaker implantation. Eradication of infection associated with pacemakers requires complete removal of all hardware, including inactive leads. Since 1972, 5,089 patients have had 8,508 pacemaker generators implanted at Montefiore Medical Center. There were 91 infections (1.06%); four of our patients required surgical removal. Nine additional patients were referred for surgical removal of infected transvenous pacemaker leads from other institutions. Surgical methods for removal included use of cardiopulmonary bypass or inflow occlusion. Surgery may be safely used in unstable or elderly patients and should not be reserved as a last resort. This article reviews our surgical experience removing infected pacemaker leads at Montefiore Medical Center.
Comparative Atrioventricular Node Properties After Radiofrequency Ablation and Operative Therapy of Atrioventricular Node Reentry
Authors: NATALE ANDREA , WATHEN MARK , WOLFE KEVIN , YEE RAYMOND , GUIRAUDON GERARD M. , KLEIN GEORGE J.
Published: July 2006

The anatomical substrate for atrioventricular (AV) node reentry is unclear. To gain insights into the mechanism of cure of AV node reentry by nonpharmacological techniques, we compared AV node properties in 53 patients undergoing operative therapy (perinodal dissection) and 43 undergoing radiofrequency ablation (28 posterior approach, 15 anterior approach). Anterior radiofrequency ablation was associated with significant AH prolongation (62 ±18 msec vs 136 ± 64 msec, P < 0.0001), loss of “fast” pathway physiology, and no change in the anterograde refractory period of the AV node (273 ± 24 msec vs 268 ± 28 msec, P = NS). Posterior radiofrequency ablation did not change the AH interval (67 ± 17 msec vs 68 ± 17 msec, P = NS), prolonged AV node effective refractory period (275 ± 48 msec vs 320 ± 55 msec, P < 0.0001), and was associated with loss of “slow pathway” physiology. Operative treatment prolonged the AH interval (66 ±18 msec vs 83 ± 37 msec, P < 0.0001) and the AV node effective refractory period (264 ± 52 msec vs 364 ±112 msec, P < 0.0001), and affected dual pathway physiology inconsistently. These data support the view that the “fast” and “slow” pathways are distinct perinodal entities that can be selectively ablated. The operative approach causes more diffuse and variable injury to the AV node region.
Efficacy of Pacemaker Tachycardia Termination Algorithms: Is Electrophysiological Testing Alone Adequate?
Authors: EHRLICH STEPHEN , SHANDLING ADRIAN , CRUMP RANDY , LI CURTIS
Published: July 2006

Selection of an optimal pacemaker tachycardia reversion algorithm is generally performed utilizing programmed electrical stimulation (PES). Multiple tachycardias are induced and various tachycardia termination protocols are tested for reversion success. However, PES may induce nonclinical tachycardia and result in an inaccurate assessment of subsequent reversion effectiveness for spontaneous tachycardia. To investigate this question, we compared tachycardia reversion protocol success for PES‐induced tachycardia versus spontaneously occurring tachycardia in 16 patients with atrially placed Intermedics 262–12 antitachycardia pacemakers. The pacemaker has tachycardia response counters, and the reversion success was calculated from these counters. This was performed by comparing the percent of time 1° versus 2° modality use occurred; crossover to the 2° modality implied failure of the 1° modality to convert the tachycardia. PES was used to induce multiple episodes of tachycardia and spontaneous episodes of tachycardia were recorded over time by pacemaker counters. The pacemaker 1° modality success was then compared for spontaneous and induced arrhythmias. Results: A total of 53 discrete data comparisons of PES versus spontaneous tachycardia counters were performed in the 16 patients. PES reversion success occurred 85%± 22% of the time versus a spontaneous reversion success of 88%± 22%. However, the Spearman rank correlation coefficient test demonstrated nonsignificant overall correlation (P < 0.1), and Pearson correlation on an individual patient basis varied widely (r value from < 0.1 to 1.0). Conclusions: When utilizing the same termination algorithm, the percentage conversion of tachycardias occurring spontaneously and induced by PES is similar but does not correlate well overall. This suggests that PES may not be a good linear predictor of the long‐term success of antitachycardia pacing algorithms.
Comparison in the Same Patient of Aberrant Conduction and Bundle Branch Reentry After Dofetilide, a New Selective Class III Antiarrhythmic Agent
Authors: CRIJNS HARRY J.G.M. , KINGMA J. HERRE , GOSSELINK A.T. MARCEL , LIE KI
Published: July 2006

Dofetilide may induce aberrant intraventricular conduction due to its Class III effect. This report describes an atrial fibrillation patient in whom intraventricular conduction was studied before and after dofetilide using multiple endocardial recordings. Dofetilide provoked aberrant conduction during atrial fibrillation, and aberrancy could be mimicked with programmed atrial stimulation after restoration of sinus rhythm. However, during right ventricular slimulation, isolated bundle branch reentrant beats were recorded after induction of critical retrograde conduction delays. This occurred in the setting of relatively large differences in refractoriness between the right bundle branch and the right ventricular myocardium. This favored distal retrograde bundle branch block during ventricular extrastimulation, in turn enhancing bundle branch reentry. This potendal proarrhythmic mechanism deserves close attention in the further deveiopmeni of dofetilide and also of other new “pure” Class III agents.
Frequency Versus Time Domain Analysis of the Signal‐Averaged Electrocardiogram: Reproducibility of the Spectral Turbulence Analysis
Authors: KULAKOWSKI PIOTR , MALIK MAREK , ODEMUYIWA OLUSOLA , STAUNTON ANNE , CAMM A. JOHN
Published: July 2006

Reproducibility of the Spectral Turbulence Analysis. Spectral turbulence analysis (STA) of the signal‐averaged electrocardiogram (ECG) is a new frequency domain method that analyzes the total high gain QRS complex and not only its terminal portion. This study examined the qualitative and quantitative short‐term reproducibility of this technique (three recordings made within 25 min) in 68 subjects: 16 healthy volunteers; 22 patients with ventricular tachycardia and no evidence of heart disease; and 30 postinfarction patients with sustained ventricular tachycardia. The reproducibility of diagnosis of the STA was compared with that of the conventional time domain analysis of the signal‐averaged ECG using standard criteria of abnormality. The reproducibility of numeric values of the spectral turbulence and of the time domain indices was performed by computing the ratios between standard deviation of measurements in individual subjects and standard deviations of all measurements. The reproducibility of diagnostic conclusions of the time domain analysis was slightly better than that of the STA but the differences were not significant (88%–91% of consistent time domain results vs 84% of consistent STA results). The numeric reproducibility of three STA parameters was slightly but not significantly inferior to that of the time domain indices whereas the reproducibility of the fourth STA variable, the intersegment correlation standard deviation (ISCSD), was significantly worse than that of the other indices. Of the two different ECG segments analyzed, the reproducibility of the STA variables calculated for the total QRS region was significantly better than that of the terminal low power QRS region. In conclusion, the qualitative and quantitative reproducibility of the STA is slightly but not significantly worse than that of the time domain analysis with the exception of the ISCSD, which is significantly less reproducible than all other parameters.
Pacing System Analyzers: Different Systems—Different Results
Authors: WILSON JOHN H. , SIEGMUND JOACHIM B. , JOHNSON ROBERT , LATTNER STEPHEN E. , FAHNER SUSAN P.
Published: July 2006

When a pacemaker is implanted, several electrophysiological parameters are measured using pacing system analyzers (PSA). Different PSAs may use different filter settings and measuring techniques when compared to the implanted pacemaker. In order to determine if there were significant differences in measurements obtained with different PSAs, we obtained measurements in a group of 99 patients with three different PSAs and a manual method. The results show that with each of the three different PSAs tested, different amplitudes of intracardiac electrograms are obtained and that they are usually higher than those obtained by manual measurement of recorded electrograms. Despite significant differences, however, all methods correlate well with each other. Following common practice of pacemaker programming, the use of a PSA for the implantation of a pacemaker that uses different sensing technique does not lead to clinical complications.
Preliminary Experience with Nonthoracotomy Implantahle Cardioverter Defihrillators in Young Patients
Authors: KRON JACK , SILKA MICHAEL J. , OHM O‐J. , BARDY GUST , BENDITT DAVID ,   for THE MEDTRONIC TRANSVENE INVESTIGATORS
Published: July 2006

Implantable cardioverter defihrillators represent an important treatment option for patients with life‐threatening tachyarrhythinias. However, the requirement for surgical access to the thorax contributes to significant procedural morbidity with ICD implantation. This study was performed to assess an initial experience with a nonthoracotomy approach to ICD lead implantation in young patients. An international survey identified 17 patients, ranging in age from 12–20 years (mean = 16.7 ± 2.4) and weighing from 33–89 kg (mean = 60.6 ± 13.3), who had undergone placement of the Medtronic TransveneR defibrillator lead system. Implant indications were aborted sudden cardiac death in 15 patients and recurrent ventricular tachycardia or familial sudden death in 2 patients. At a median follow‐up of 7.9 months, 9 of 17 patients had received at least one ICD therapy. There have been no deaths. Complications included patch or generator erosion (3 patients), lead dislodgement (1 patient), and ICD system infection requiring explanation (1 patient). The initial experience with nonthoracotomy ICDs in young patients appears promising. This approach may be particularly advantageous for patients who have undergone prior thoracotomy. Prospective clinical trials will be required to establish the applicability of these lead systems to select patient populations.
Conductive Property of the Zone of Slow Conduction of Reentrant Ventricular Tachycardia and Its Relation to Pacing Induced Terminability
Authors: AIZAWA MASAMI , AIZAWA YOSHIFUSA , CHINUSHI MASAOMI , TAKAHASHI KAZUYOSHI , SHIBATA AKIRA
Published: July 2006

In order to assess the functional characteristics of the zone of slow conduction of reentrunt VT, rapid pacing was performed to entrain VT. The orthodromic conduction time was measured as the interval between the stimulus and the orthodromically captured electrogram recorded distal to the zone of slow conduction, hut not precisely at the exit point, and its response to rapid pacing was evaluated. In 32 of 33 consecutive patients, rapid pacing was performed to entrain VT. Of these, rapid pacing was repeated in 28 patients at 3–10 cycle lengths in steps of 10 msec before VT was terminated, or rapid pacing produced an acceleration of the rate. A pacing induced prolongation of the orthodromic conduction time (slowed conduction) was observed in 16 (57.1%) patients and in another 12 (42.9%) patients, the conduction time was constant. The pacing induced termination was observed in 93.8% of VT with slowed conduction and in 50% of VT with constant conduction, and the difference was significant (P < 0.05). There was no difference in the cycle length of VT or the shortest paced cycle length between VT with and without slowed conduction. The zone of slow conduction in human VT showed different conductive properties and VT with slowed conduction was associated with an easier and safer terminability with rapid pacing. The fact might be useful in selecting patients for antitachycardia pacing.
Loss of Late Potentials After Radiofrequency Catheter Ablation of Recurrent Ventricular Tachycardia in a Patient with Right Bundle Branch Block
Authors: TEBBENJOHANNS JÜRGEN , PFEIFFER DIETRICH , SCHUMACHER BURGHARD , JUNG WERNER , MANZ MATTHIAS , LÜDERITZ BERNDT
Published: July 2006

The case of a patient with a history of myocardial infarction and recurrent ventricular tachycardia undergoing attempted radiofrequency catheter ahlation with loss of late potentials is described. Prior to energy delivery fractionated, late activation could be found using the signal‐averaged ECC despite the presence of a right bundle branch block. After successful catheter ablation, the clinical ventricular tachycardia was no longer inducible and the signal‐averaged ECG, recorded the next day, showed marked changes indicating loss of late potentials. Our report emphasizes the possibility of late potential recordings despite the presence of bundle branch block.
Upper Rate Lockout: An Unexpected Feature of Rate Adaptive Atrioventricular Delay
Authors: HESSEN SCOTT E. , SHEPPARD ROBERT C. , KUTALEK STEVEN P.
Published: July 2006

We present a case in which use of rate adaptive AV delay resalted in unexpected pacemaker 2:1 AV block when the patient's atrial rate exceeded the pacemaker maximum tracking rate but was below the predicted multiblock rate. “Lockout” of normal upper rate behavior was accompanied with the requirement of a slower atrial rate for reassociation than loss of atrial tracking, a form of upper rate hysteresis. The mechanism of upper rate lockout is discussed, along with potential ways to avoid the problem. The use of software based pacemakers with an extended range of programmable options allows the most flexibility in optimizing pacemaker performance in an individual patient.
Effect of Low Dose Aspirin on Augmented Piasminogen Activator Inhibitor Type 1 Activity in Patients with Permanent Pacemakers
Authors: ABE HARUHIKO , TAKAHARA KAZUO , NAKASHIMA YASUHIDE , KUROIWA AKIO
Published: July 2006

To clarify the activity states of coagulation and fibrinolysis in patients with a permanent pacemaker, we studied 29 patients more than 4 months after operation. They were divided into a single pacemaker lead group (S, n = 14) and a double lead group (D, n = 15). Prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin III, tissue‐type plasminogen activator (tPA) activity, plasminogen activator inhibitor type‐1 (PAI‐1) activity, and platelet aggregation were measured and compared to those in an age‐matched control group (C, n ‐ 7). The effects of low dose aspirin (81 mg/day) in the patients (n = 21) were also studied 2 weeks after administration. PAI‐1 activity in groups S and D was significantly higher than that in the group C (53.5 ± 36.5, 86.8 ± 59.2 ng/ mL vs 19.4 ± 7.2 ng/mL; P < 0.01 and P < 0.005). Platelet aggregation induced by collagen was slightly higher in groups S and D than group C. Other parameters were not significantly different. In the patients, low dose aspirin significantly suppressed collagen induced platelet aggregation (71.8 ± 20.3% vs 41.7 ± 28.3%; P < 0.005), but not PAI‐1 activity. tPA activity was increased significantly by the low dose aspirin administration (3.94 ± 1.85 ng/mL vs 2.48 ± 1.19 ng/mL; P < 0.005). Thus, PAI‐1 activity in patients with a permanent pacemaker is elevated, and the activity is not suppressed by low dose aspirin unlike the platelet aggregation.
Signal‐Averaged Electrocardiography in Elderly Subjects With and Without Heart Disease
Authors: MERCANDO ANTHONY D. , ARONOW WILBERT S. , EPSTEIN STANLEY , FISHBACH MITCHELL
Published: July 2006

Prevalence of abnonnal signal‐averaged electrocardiography in normal populations ap pears to be low, but has not been studied previously in an asymptomatic elderly population. To study the prevalence of abnormal ventricular late potentials in an elderly population, a group of 51 subjects with no evidence of cardiac disease and ranging In age from 62 to 102 years underwent signal‐averaged electrocardiography. Results were compared to a group of 179 patients similar in age but with complex ventricular arrhythmias, and to a group of 25 asymptomatic volunteers under the age of 50. The prevalence of an abnormal signal‐averaged ECG was 14% in the normal elderly subjects, and 31 % in the patients (P = 0.01), and 4 % in the young subjects (P = NS). We conclude that the prevalence of abnormal ventricular late potentials in elderly patients without heart disease is similar to levels reported in other populations of normal controls, but elderly patients with cardiac disease have a significantly higher prevalence of abnormal signal‐averaged ECG studies than the normals.
Demonstration of Entrainment and Presence of Slow Conduction During Ventricular Tachycardia in Arrhythmogenic Right Ventricular Dysplasia
Authors: YAMABE HIROSHIGE , OKUMURA KEN , TSUCHIYA TAKESHI , YASUE HIROFUMI
Published: July 2006

During VT in two cases with arrhythmogenic right ventricular dysplasia, entrainment criteria, constant fusion beats except for the last entrainment beat, progressive fusion, and a localized conduction block associated with interruption of VT, were demon strated with rapid ventricular pacing performed during VT. Furthermore, a long conduction interval was present during entrainment from the pacing site to the earliest activation site during VT. indicating the presence of a slow conduction area. VT in these cases was, thus, due to reentry with an area of slow conduction within the circuit.
Unipolar Electrogram Models for Prediction of Outcome in Radiofrequency Ablation of Accessory Pathways
Authors: SIMMERS TIMOTHY A. , HAUER RICHARD N.W. , WEVER ERIC E.D. , WITTKAMPF FRED H.M. , de MEDINA ETIENNE O. ROBLES
Published: July 2006

Meticulous catheter positioning dose to the accessory pathway is essential for successful radiofrequency ablation. The aim of this study was to identify local unipolar electrogram characteristics predictive of radiofrequency ablation outcome, enabling more accurate accessory pathway localization and catheter positioning. So far mainly bipolar electrogram parameters have been evaluated, stressing the importance of the presence of an accessory pathway potential. However, especially in the absence of this parameter, the unipolar recording mode can be expected to hold severol advantages. Nine local unipolar electrogram characteristics were analyzed in preexcited sinus rhythm directly preceding radiofrequency pulses in 35 consecutive patients with a manifest occessory atrioventricular pathway. A total of 1,230 unipolar electrogram complexes were analyzed and recorded at 138 ablation sites. Ablation was successful in 30/35 patients (86%). Multivariate analysis provided two unipolar models for prediction of ablation outcome: in Model I, sites with a suspected accessory pathway potential, local AV interval ≤ 30 msec and catheter stability had 76% probability of success, but no more than 1% in their absence. In contrast, using the bipolar recording mode, presence of a suspected accessory pathway potential was the only one of these parameters shown to differentiate between successful and unsuccessful sites, with a predicted chance of success of 48%. Model II, not requiring assessment of possible accessory pathway potentials, showed a 63% probability of success for the combination of initial positivity of the local ventricular signal ≤ 0.1 mV, AV interval ≤ 30 msec, and catheter stability, but no more than 7% in their absence. Moreover, gradual decrease of initial ventricular positivity and AV interval while approaching a subsequently successful site allows the use of these parameters as dynamic mapping tools. Local unipolar electrogram parameters may thus facilitate precise accessory pathway localization and catheter positioning while offering important information supplementary to the bipolar mode, and enable accurate prediction of ablation outcome at a given site also in the absence of accessory pathway potential recording.
Histopathological Study Following Catheter Guided Radiofrequency Current Ablation of the Slow Pathway in a Patient with Atrioventricular Nodal Reentrant Tachycardia
Authors: GAMACHE M. CAROLYN , BHARATI SAROJA , LEV MAURICE , LINDSAY BRUCE D.
Published: July 2006

The present study examined histological changes induced by catheter guided radiofrequency current in a patient with AV nodal reentrant tachycardia who underwent cardiac transplantation 1 week after ablation of the slow pathway. During the electrophysiology study AV nodal conduction curves were discontinuous and AV nodal reentry was induced. At the conclusion of the procedure there was no evidence of slow pathway function. Histological sections from the explanted heart demonstrated a sharply demarcated atrial lesion (5 × 5 × 4 mm) extending from the septal portion of the tricuspid annulus to the posterior border of the AV node. The lesion did not encompass the compact AV node. These observations support the hypothesis that the slow pathway is comprised of atrial approaches to the AV node and is distinct from the compact AV node.
Programming a Long Paced Atrioventricular Interval May Be Risky in DDDR Pacing
Authors: PIETERSE MATTIE G.C. , den DULK KAREL , van GELDER BERRY M. , van MECHELEN ROB , WELLENS HEIN J.J.
Published: July 2006

In patients with intermittent AV block and dual chamber pacemakers, a long paced AV interval of 200 msec or more can be selected to prolong pulse generator life (by avoiding the ventricular pace output) and to enable a more physiological and hemodynamically superior activation sequence. This case report describes the potential risks of programming a long paced AV interval in a patient with a DDDR pacemaker. T wave pacing, as described here, can occur if the conducted QRS complex is not sensed because it occurs during the ventricular blanking period (delivery of the atrial stimulus). This can be initiated by the mechanisms that induce apparent and actual P wave undersensing of the conducted QRS complex. In this case report apparent P wave undersensing and subsequent T wave pacing with ventricular capture (in a patient with intermittent AV block) occurred frequently during an exercise test done in the DDDR mode with a paced AV interval of 200 msec, according to the clinical evaluation protocol.
Programmed Ventricular Stimulation Using Tandem Versus Simple Sequential Protocols
Authors: FISHER JOHN D. , KIM SOO G. , FERRICK KEVIN J. , ROTH JAMES A.
Published: July 2006

The objective was to determine whether two commonly used ventricular stimulation protocols, one more complex than the other, produced concordant results. If such were the case, the simpler protocol would streamline activities in clinical electrophysiology laboratories. Background: Two programmed ventricular stimulation protocols were compared. (1) With the tandem method, the first extrastimulus (S2) is moved stepwise to the effective refractory period and then moved out 50 msec; the second extrastimulus (S3) is then decremented until it fails to capture; S2 and S3 are then decremented in a semialternating (tandem) fashion so that both continue to capture. When S2 reaches the refractory period + 10 msec and S3 fails to capture, S3 is then moved out 50 msec, and S4 is decremented as described for S3. (2) With the simple sequential method, the first extrastimulus (S2) is decremented stepwise to the refractory period, and then moved out 10 msec to assure capture; S3 is then similarly decremented to the refractory period and then moved out 10 msec; and S4 is then similarly decremented. Methods: This was a prospective, randomized, crossover, consecutive series study. Both protocols were tested in each patient on the same day in randomized order. Results: There were 84 matched studies. Fifty‐six patients provided data from baseline electrophysiological studies, and 28 of these provided additional data during drug trials. There was a 93% concordance between the two methods, including tbe primary outcomes of inducibility of clinical arrhythmias, inducibility of nonclinical arrhythmias, and noninducibility (P < 0.001). Discordances were few and evenly distributed between the two protocols (P = NS). Results were similar for baseline studies and drug trials. The simple sequential method required less time to perform (P ≤ 0.01). Conclusions: Tandem and simple sequential protocols provide concordant results. No advantage could be demonstrated for the more complex tandem method.
Significance of Supraventricular Tachyarrhythmias in Patients with Implanted Pacing Cardioverter Defibrillators
Authors: SCHMITT CLAUS , MONTERO MARIA , MELICHERCIK JURAJ
Published: July 2006

Eighty‐six patients were treated with an implantable cardioverter defibrillator (ICD) because of sustained ventricalar tachycardia (VT) or ventricular fibrillation (VF). In 27 patients an epicardial system was used, in 59 patients a transvenous system with a subcutaneous patch electrode was implanted. During a mean follow‐up time of 17 ± 9 months, inappropriate activations of the ICD due to supraventricular tachycardia were documented by Holter monitoring in 14 patients (16%). In 8 patients paroxysmal atrial fibrillation (AF), in 2 patients chronic AF, in 1 patient atrial flutter, and in 3 patients sinus tachycardia triggered antitachycardia pacing functions (12 patients) or internal defibrillation (2 patients). In 3 patients (5%) VT was induced by inappropriate antitachycardia pacing. In an additional 18 patients (21%) inappropriate activation of antitachycardia functions due to atrial tachyarrhythmias were suspected based on telemetry readouts or the patient's history. Inappropriate activation of ICD therapy triggered by intermittent supraventricular tachyarrhythmias is common. Further improvements of detection algorithms for supraventricular tachycardia are required in future device generations.
Signal‐Averaged ECG Parameters in Cardiac Normals Using Frank Lead System and Fourier Transform Filter and Gender Specific Differences: A Multicenter Study
Authors: TIMMERMANS CARL , ECTOR HUGO , HAISTY KENNETH W. , HAMMILL STEPHEN C. , KIENZLE MICHAEL G. , OZAWA YUKIO , REDDY B.R. SHANKARA , UNDERWOOD DONALD A.
Published: July 2006

There is only limited data on normal reference values for signal‐averaged electrocardiograms (SAECGs) using Frank leads and fast Fourier transform filter (FFT). Furthermore, the influence of gender on reference values and their relation to body characteristics was only the subject of a few studies on small series of normals. One hundred eigbty‐five cardiac normals (85 women and 100 men) were examined in this multi‐center study. The obtained SAECG values (mean ± standard deviation) are as follows: filtered QRS duration (FQRSD) = 108.6 ± 7.5 msec; low amplitude signal duration < 40 μV (LASD) = 30.4 ± 8.4 msec; and root mean square voltage in the terminal 40 msec (RMSV) = 43.5 ± 20.6 μV. Between men and women, significant differences were found in FQRSD (111.7 ± 6.5 vs 105.0 ± 7.0 msec, P < 0.001) and in RMSV (38.6 ± 17.4 vs 49.4 ± 22.7 μM, P < 0.001). No difference was observed for LASD. After normalizing the three SAECG parameters for body characteristics, FQRSD normalized for height was the only variable where gender differences were eliminated. For FQRSD and LASD the 90th percentile and for RMSV the 10th percentile are proposed as cut‐off values. Only for the 90th percentile of FQRSD a clear difference between men and women was observed. The following gender specific normal values for SAECG, at 40‐Hz high pass filtering, using Frank leads and an FFT filter are proposed: for males, FQRSD < 122 msec; for females, FQRSD < 115 msec; for both genders, LASD < 41 msec and RMSV > 20 μV.
Electrophysiological Testing of Sinus Node Function: Diagnostic and Prognostic Application‐Including Updated Information From Sinus Node Electrograms
Authors: REIFFEL JAMES A. , KUEHNERT MATTHEW J.
Published: July 2006

Sinus node function, including automaticity, conduction, and refractoriness, can be studied in the human electrophysiology laboratory. This review details the current methods used for such studies and discusses their clinical value. Of special emphasis in this article is the role of sinus node electrography in the clinical laboratory. Included also is an update of the data relating the duration of sinus node depolarization as measure on sinus node electrograms to other parameters that assess sinus node function as well as data supporting the direct relationship between the duration of the sinus node depolarization and the severity of sinus node dysfunction.
Coincident Idiopathic Left Ventricular Tachycardia and Atrioventricular Nodal Reentrant Tachycardia: Control by Radiofrequency Catheter Ablation of the Slow Atrioventricular Nodal Pathway
Authors: WAGSHAL ALAN B. , MITTLEMAN ROBERT S. , And CLAUDIO D. SCHUGER. , HUANG SHOEI K. STEPHEN
Published: July 2006

A healthy 37‐year‐old male presented with a history of frequent palpitations and sustained wide QRS complex tachycardia with a right bundle branch block and left axis morphology. Serial electrophysiological studies revealed two inducible tachycardias, which were shown to represent atrioventricular nodal reentrant tachycardia and idiopathic left ventricular tachycardia. Transformation from one tachycardia to the other occurred spontaneously as well as following atrial or ventricular pacing. Radiofrequency catheter ablation of the slow atrioventricular nodal pathway resulted in cure of atrioventricular nodal reentrant tachycardia and the prevention of spontaneous recurrence of ventricular tachycardia, suggesting a role of atrioventricular nodal reentrant tachycardia in triggering the clinical episodes of ventricular tachycardia. The patient has remained asymptomatic without antiarrhythmic therapy for 8 months.
Baroreflex Sensitivity: Methods, Mechanisms, and Prognostic Value
Authors: VANOLI EMILIO , ADAMSON PHILIP B.
Published: July 2006

A large bulk of data collected over the last 25 years links reflex autonomic activation during acute myocardial ischemia with risk of developing lethal arrhythmias. Specifically, evidence obtained in an experiniental preparation in chronically infarcted dogs supported the concept that sympathetic hyperactivity enhances likelihood for ventricular tachyarrhythmias, vagal activation exerts protective effects. Based on this knowledge, it was first proposed by our group that analysis of aufonomic control of heart rate could provide information relevant to risk stratification in post‐myocardial infarction individuals. Among several possibilities, baroreflex sensitivity ivas evaluated by correlating blood pressure rise induced by bolus injections of phenylephrine with the consequent beat to beat R‐R interval lengthening. Experimental studies involving direct recordings from single neural vagal fibers directed to the heart documented that baroreflex sensitivity closely reproduces cardiac vagal activity. In a large group of conscious dogs it was shown that a depressed baroreflex sensitivity was highly predictive of the risk for ventricular fibrillation during acute myocardial ischemia. The clinical prognostic value of baroreflex sensitivity has already been confirmed in pilot studies conducted by different groups of investigators. Overall, the phenylephrine test has been performed in several hundred patients with no reports of side effects. An ongoing multicenter study, the ATRAMI (Autonomic Tone and Reflexes After Myocardial Infarction) is aimed to definitively assess the predictive value of baroreflex sensitivity and heart rate variability in patients with a prior myocardial infarction, While the enrollment is still ongoing, this study has already provided an important methodological information about the possibility of using non invasive technique to record blood pressure by means of FINAPRES, to evaluate baroreflex sensitivity. Comparison among 142 tests performed with simultaneous recording from an intraarterial line and from FINAPRES indicated a strong correlation (r = 0.9) between the two methods. ATRAMI is expected to close the enrollment in the near future. To date, baroreflex sensitivity appears to be a safe and non‐invasive test likely to provide meaningful information on autonomic balance and consequently on risk profile of patients with a prior myocardial infarction.
Empiric Therapy with β‐Blockers
Authors: HJALMARSON ÅKE
Published: July 2006

The only class of drugs with significant effects on ventricular fibrillation and sudden death in humans is that of β‐blockers. The exact mechanisms for these prophyiactic effects are not knotvn but may be related to both ontiischemic or anliarrhythmic infiuences. It seems reasonable to suggest that one should use a β‐blocker with proven effect on total mortality and sudden cardiac death after myocardial infarction as prophylaxis. Therefore, propranolol, timolol. or metoprolol. should be instituted in order to improve prognosis when there are no conlraindications. In addition to possible effects on survival one would aiso expect to reduce the risk for new ischemic events with angina or reinfarction. In contrast, class I antiarrhythmic agents are useful for symptomatic ventricular arrhythmias but there is no proof for any effect on ventricular fibrillation and sudden cardiac death.