bluuebunny/crossref_metadata_2025 huggingface dataset:
The NASPE */BPEG ** Defibrillator Code
Authors: BERNSTEIN ALAN D. , CAMM A. JOHN , FISHER JOHN D. , FLETCHER ROSS D. , MEAD R. HARDWIN , NATHAN ANTHONY W. , PARSONNET VICTOR , RICKARDS ANTHONY F. , SMYTH NICHOLAS P.D. , SUTTON RICHARD , TARJAN PETER P.
Published: July 2006

A new generic code, patterned after and compatible with the NASPE/BPEG Generic Pacemaker Code (NBG Code) was adopted by the NASPE Board of Trustees on January 23. 1993. It was developed by the NASPE Mode Code Committee, including members of the North American Society of Pacing and Electrophysiology (NASPE) and the British Pacing and Electrophysiology Croup (BPEC). It is abbreviated as the NBD (for NASPE/BPEC Defibrillator) Code. It is intended for describing the capabilities and operation of implanted cardioverter defibrillators (ICDs) in conversation, record keeping, and device labeling, and incorporates four positions designating: (1) shock location; (2) antitachycardia pacing location; (3) means of tachycardia detection; and (4) antibradycardia pacing location. An additional Short Form, intended only for use in conversation, was defined as a concise means of distinguishing devices capable of shock alone, shock plus antibradycardia pacing, and shock plus antitachycardia and antibradycardia pacing.
Clinical Experience with the Extrathoracic Introducer Insertion Technique
Authors: BYRD CHARLES L.
Published: July 2006

The extrathoracic approach to transvenous introducer insertion into the subclavian vein was initially described as an alternative approach in “Safe Introducer Technique for Pacemaker Lead Implantation.” Since this technique was so successful as an alternative approach, it was tried as the primary approach in 213 consecutive cases. The subclavian vein was cannulated in all cases. There were no introducer related complications. The extrathoracic approach cannulates the subclavian vein as it passes over the body of the first rib prior to entering the thoracic inlet. The technique includes maneuvering the introducer needle from the clavicle to the first rib by a series of partial withdrawals and reinsertions, visualized by fluoroscopy, The needle is advanced posteriorly along the rib until the vein is punctured. Orientation is maintained by touching the rib with each maneuver. The early results of the extrathoracic approach reinforces the belief that a complication‐free, transvenous introducer approach can he achieved.
Malposition of Transvenous Pacing Lead in the Left Ventricle
Authors: GHANI MANSURA , THAKUR RANJAN K. , BOUGHNER DEREK , MORILLO CARLOS A. , YEE RAYMOND , KLEIN GEORGE J.
Published: July 2006

Malposition of pacemaker leads has been described in several locations but rarely in the left ventricle. The incidence and clinical course of this pacemaker complication are unknown. We describe clinical, electrocardiographic, chest X ray, and echocardiographic findings in four patients in whom the transvenous pacing lead was inadvertendy placed through the interatrial septum and mitral valve into the left ventricle, in these patients, lead misplacement was not recognized at the time of implantation and lead malposition was diagnosed a mean of 2 years later. All four patients had right bundle branch block configuration paced complexes. In retrospect, chest X rays suggested atypical lead position in all, but the initial posterioranterior and lateral chest X rays were misinterpreted and contributed to the delay in diagnosis. When lead misplacement in the left ventricle was considered it was confirmed by two‐dimensional echocardiography. One patient subsequently presented with a stroke and the remainder were diagnosed when they presented with other unrelated problems. Pacing thresholds were normal at the time of implantation and behaved normally during follow‐up. The patient presenting with stroke was anticoagulated and the other three have been managed expectantly without anticoagulafion. Diagnosis of left ventricular lead malposition is not difficult but requires a high index of suspicion. A 12‐lead ECC and posterior‐anterior and lateral chest X rays after implantation can be diagnostic. Patients with pacing lead in the left ventricle may remain asymptomatic with normal lead function during long‐term follow‐up. Anticoagulation should be considered when this problem comes to attention for the first time during follow‐up.
Patient Acceptance of the Implantable Cardioverter Defibrillator in Ventricular Tachyarrhythmias
Authors: LÜDERITZ BERNDT , JUNG WERNER , DEISTER ARNO , MARNEROS ANDREAS , MANZ MATTHIAS
Published: July 2006

Besides surgical problems, recipierifs of implantable cardioverter defibrillators (ICDs) are faced with psychological and social adjustments. Successful ICD therapy is influenced by the patients’ perceived concerns regarding device, discharge, changes in life style, and complications. In order to assess patients’ acceptance of the ICD, the psychological profile of 57 consecutive patients was evaluated using a specifically designed questionnaire and the State Trait Anxiety Inventory (STAI). The results showed that 20 patients staled fear of ICD discharge, 12 patients revealed physical discomfort due to the device, and limited quality‐of‐life occurred in 8 patients. Fifty‐five of 57 patients answered that it was worth having an ICD device implanted, 30 (53%) patients returned to active life, and 56 (98%) would advise another patient to undergo implantation if necessary. Overall, there was only a slight, but insignificant, decrease in the level of anxiety within the total patient population after ICD implantation. However, a comparison of two subgroups indicated that the state of anxiety was significantly higher in patients < 50 years of age as well as in patients having received > 5 shocks versus those > 50 years of age and having experienced < 5 shocks. In general, the acceptance of the ICD as a tool in managing life‐threatening ventricular tachyarrhythmias is high. Besides the increased survival rate, quality‐of‐life and patient acceptance are important criteria for successful ICD therapy.
Initial Experience with a New Single Chamber, Dual Sensor Rate Responsive Pacemaker
Authors: CONNELLY DEREK T. ,   THE TOPAZ™ STUDY GROUP
Published: July 2006

In August 1991, a new single chamber pacemaker became available that utilizes information from two sensors, activity and stimulus‐to‐T wave (QT) interval. We are reporting on the first 90 implants in 21 centers. T wave sensing was adequate at implantation in 88/90 patients, with a safety margin of > 100% in 86/90, Activity sensing was adequate in all patients. The contribution of each sensor fsensor blending) is programmable for each patient. Of 75 patients assessed at 1 month after implant, three have been programmed to “Activity‐Only” mode, and 72 to dual sensor mode. Of these, 18 have been programmed to “QT < Activity,” 48 to “QT = Activity,” and 6 to “QT > Activity.” Forty‐five patients underwent exercise testing in dual sensor mode and a subgroup of 15 also underwent exercise testing in Activity‐Only mode. The dual sensor mode produced a more gradual increase in pacing rate. Sensor Cross Checkingtmsatisfactorily prevented a sustained high pacing rate in tests of false‐positive activity sensing (tapping, vibrating pacemaker, or static pressure). The maximum pacing rate on walking downstairs (94.2 ± 7.2 ppm) was similar to that produced by walking upstairs (91.6 ± 5.9 ppm). We conclude that initial assessment of this dual sensor, single chamber, rate responsive pacemaker confirms that the algorithm for combining data from two sensors functions satisfactorily. Dual sensor rate responsive pacing may offer significant advantages over single sensor devices, and further studies of this novel device are indicated.
Radiofrequency Catheter Ablation of the Slow Reentrant Pathway of Sustained Ventricular Tachycardia
Authors: OMETTO RENATO , BEDOGNI FRANCESCO , La VECCHIA LUIGI , FINOCCHI GIUSEPPE , MOSELE GIAN MARCO , VINCENZI MARIO
Published: July 2006

The article reports the cases of two patients with severe coronary artery disease and associated recurrent sustained ventricular tachycardia successfully treated with radiofrequency catheter ablation. In the first patient, two different types of ventricular tachycardia (one incessant) were eliminated. In all procedures, an area of slow conduction critical for tachycardia maintenance was localized by endocardial mapping techniques. Radiofrequency energy delivered to this area could permanently modify the anatomical substrate of the arrhythmia. After single follow‐ups of 19, 14, and 13 months regarding the arrhythmic entities, the patients are well and free from spontaneous recurrences.
The Use of Transcranial Doppler in the Hemodynamic Assessment of Implanted Pacemakers
Authors: COPPERMAN YITSCHAK , BORNSTEIN NATAN M. , NISSEL TANIA , LANIADO SHLOMO
Published: July 2006

Twenty patients with DDD pacemakers had their intracranial cerebral circulation assessed in different pacing modes, using transcranial Doppler. The studies were performed at the vertebral artery in a sitting position. Although DDD pacing was pre/ered to VVI pacing in 18 of the 20 patients, the figures did not reach statistical significance. There was no stotistical difference in maximal blood flow velocity between DDD pacing at 60 and 80 beats/min. Varying the AV interval from 150–250 msec also demonstrated no clear difference in maximal peak Doppler velocity, in the group as a whole, though there was a greater individual preference for 150 msec. Transcranial Doppler assessment of the hemodynamics of the cerebral circulation is of limited value as an indicator of mode or rate preference in the pacemaker population.
Does Atrial Fibrillation Cause False‐Positive Late Potentials?
Authors: BUCKINGHAM THOMAS A. , RADIN MICHAEL M. , VOLGMAN ANNABELLE S. , JHANGIANI ANIL , ZBILUT JOSEPH
Published: July 2006

We hypothesized that atrial fibrillation may cause false‐positive late potentials due to the recording of baseline atrial activity. We performed signal‐averaged ECGs in 26 patients with atrial fibrillation before and after conversion to normaJ sinus rhythm. Signal‐averaged ECGs were recorded for > 200 cycles with a noise level of ≤ 0.5 μV. The signals were band‐pass filtered at 40–250 Hz. We examined filtered QRS duration (fQRS), duration of low amplitude signal < 40 μV (LAS), and the root mean square (RMS) of the terminal 40 msec of the QRS complex. A late potential was considered present when two of the following three criteria were met: fQRS ± 114 msec, LAS ± 38 msec, and RMS ≤ 20 μV. The mean ± standard deviation of the fQRS in atriai fibrillation and sinus rhythm were 313 ± 28 and 110 ± 25 msec; of the LAS 38 ± 17 and 37 ± 15 msec; of the RMS 27 ± 22 and 28 ± 21 μV; of the noise 0.25 ± 0.08 and 0.22 ± 0.07 μV (P = NS). Ten signal‐averaged ECGs in atrial fibrillation had late potentials. With reversion to sinus rhythm one of these 26 patients gained a late potential; two others lost a late potential (P = NS by McNemar's Chi‐square). There was no significant difference in the signal‐averaged ECG parameters or noise levels. In conclusion, signal‐averaged ECG parameters are not significantly changed by cardioversion of atrial fibrillation to normal sinus rhythm. Moreover, the presence of a late potential in a patient with atrial fibrillation does not appear to be the result of a spurious recording of baseline atrial fibrillatory activity.
Can Amiodarone Pulmonary Toxicity Be Predicted in Patients Undergoing Implantable Cardioverter Defibrillator Implantation?
Authors: HAWTHORNE HARRY R. , WOOD MARK A. , STAMBLER BRUCE S. , DAMIANO RALPH J. , ELLENBOGEN KENNETH A.
Published: July 2006

Implantable cardioverter defibrillator (ICD)implantation is rapidly becoming accepted as primary therapy for malignant ventricular arrhythmias. Many patients undergoing ICD implantation are on concomitant antiarrhythmic drugs to decrease shock frequency, slow tachycardia rate, and suppress supraventricular arrhythmias. Amiodarone is a potent antiarrhythmic agent that is also frequently used in the treatment of patients with refractory ventricular arrhythmias. Ten to forty percent of patients undergoing ICD implantation will also be taking amiodarone. It has been reported to cause pulmonary toxicity in about 5% of patients per year. Acute amiodarone toxicity presenting as adult respiratory distress syndrome has been reported much less frequently. Although perioperative morbidity due to amiodarone has been described, the risk, predictability, and consequences of acute pulmonary toxicity from amiodarone in patients undergoing ICD implantation have not been previously described. We reviewed the records of 99 consecutive patients undergoing ICD implantation at our institution from October 1987 to April 1992. Thirty‐nine patients were taking 480 ± 230 mg of amiodarone (median 400 mg, lower 20th percentile 400 mg, upper 80th percentile 800 mg)for 291 ± 554 days prior to ICD implantation. Ten patients taking amiodarone developed acute pulmonary toxicity clinically manifesting as diffuse pulmonary infiltrates on chest radiography and adult respiratory distress syndrome with hypoxia (arterial pO2 < 60 mmHg)without evidence of pneumonia or elevated pulmonary capillary wedge pressure (PCW ±15 mmHg). Of the 60 patients not taking amiodarone none developed adult respiratory distress syndrome. There was no relationship between the clinical variables of age, type of anesthesia, ejection fraction, dose or duration of amiodarone use, number of intraoperative ICD test shocks, operative time, or intraoperative FIO2. Compared to patients on amiodarone who did not develop toxicity, patients with amiodarone pulmonary toxicity had prolonged intensive care unit stays (17.1 ± 16.9 days vs 3.5 ± 1.5 days, P < 0.001), as well as prolonged ventilator dependence (9.1 ± 18.7 days vs 0.9 ± 1.1 days. P = 0.02). Acute amiodarone pulmonary toxicity resulted in a widely variable clinical syndrome that occurred 1–5 days after surgery. In conclusion, pulmonary toxicity was not predicted by clinical orhemodynamic variables, results in markedly prolonged ventilator dependence and intensive care unit stays, and may result in death.
The Importance of Timing Muscle Contraction in Dynamic Cardiomyoplasty
Authors: GEDDES L.A. , JANAS W. , BOURLAND J.D. , COOK J. , HINDS M.
Published: July 2006

This acute dynamic cardiomyoplasty (CMP)study used ten dogs (weight range 21–32 kg)and was designed to determine the importance of the train of stimuli initiation time when applied to the thoracodorsal nerve, which innen‐ates the latissinius dorsi (LD)muscle that is wrapped around the ventricles. Using the P wave of the cardiac electrogram to trigger a special delay circuit, the stimulus train could be initiated from the apex of the R wave to any time throughout and at the end of the isovolumic period, signaled by opening of the aortic valve. The cardiac electrogram (which contained the R wave), left ventricular pressure (LVP), aortic flow velocity (AFV), beat‐by‐beat stroke volume (SV), femoral artery pressure, and the envelope of the stimulus train were recorded as the onset of the stimulus train was varied from the R wave to the end of the isovolumic period with a pumping ratio of one LD contraction for every seven ventricular contractions. In four dogs there was a pronounced increase in the augmentation in LVP, AFV, and SV when the stimulus train was initiated later than 40 msec after the first peak of the R wave. In five dogs the augmentation in LVP, AFV, and SV was not as clearly apparent, although all of these dogs exhibited an optimal train delay. Data were not obtained on one dog due to an anomalous LD muscle blood supply. For all of the dogs, the optimum train delay from the R wave averaged 58 msec (range 40–80 msec). The average augmentation in SV was 26% (range 13%–45%). The same muscle‐wrap tightness was used in all dogs. In one dog, the muscle‐wrap tightness was varied, and by tightening the wrap the SV augmentation increased from 17% to 27%. For all dogs the range of augmentation in SV (13%–45%)perhaps represents variations in muscle‐wrap tightness, which may be a major uncontrolled factor in dynamic CMP.
Effect of Steroid Eluting Versus Conventional Electrodes on Propafenone Induced Rise in Chronic Ventricular Pacing Threshold
Authors: CORNACCHIA DANIELE , FABBRI MAURO , MARESTA ALEARDO , NIGRO PASQUALE , SORRENTINO FRANCESCO , PUGLISI ANDREA , RICCI RENATO , PERALDO CARLO , FAZZARI MASSIMO , PISTIS GIANFRANCO , SESTU PIERO , MEREU DIONIGI , De SETA FRANCESCO
Published: July 2006

The aim of this study was to evaluate chronic ventricular pacing threshold increase after oral propafenone therapy. Eighty‐three patients affected by advanced atrioventricular hJock and sick sinus syndrome were studied at least 3 months after pacemaker implantation, before and after oral propafenone therapy (450–900 mg/day based on body weight). The patients were subdivided into three groups according to the type of unipolar electrode that was implanted: group I (41 patients)Medtronic CapSure 4003, group II(30 patients)Medtronic Target Tip 4011, and group III (12 patients)Osypka Vy screw‐in lead. In all cases a Medtronic unipolar pacemaker was implanted: 30 Minix, 23 Activitrax, 14 Elite, 12 Legend, and 4 Pasys. Propafenone biood level was measured in 75 patients 3–5 hours after propafenone administration. The pacing autothreshoid was measured at 0.8 V, 1.6 V, and 2.5 V by reducing puise width. At the three different outputs before and after propafenone, threshold increments were significantly lower in group I in comparison with group II and group III (propafenone ranging from < 0.001 to < 0.05). No significant difference was found in pacing impedance or in propafenone plasma concentration in the three groups. Strength‐duration curves were drawn for each group at baseline and after propafenone administration. Before propafenone, in group I, the knee was markedly shifted to the left and downward as compared to the classic curve, so that the steep part was predominant; in group II and group III this shift was progressively less evident. After propafenone we found the curve shifted to the right with the flat part progressively more evident in group II and group III as compared to group I. We conclude that steroid eiuting leads cause less threshold increase than conventionol and screw‐in ones after oral propafenone, thus leading to safer chronic pacing. Chronic pacing at 2.5‐V amplitude and 0.6‐msec width was feasible in 97% of group I patients and in 80% of group II patients, but not in group III due to an insufficient safety margin.

propafenone, pacing threshold
Radiofrequency Catheter Ablation of Right Ventricular Outflow Tract Tachycardia Late After Complete Repair of Tetralogy of Fallot Using the Pace Mapping Technique
Authors: BURTON M. ERICK , LEON ANGEL R.
Published: July 2006

While surgical repair of tetralogy of Fallot has improved the long‐term outlook for this patient population, sudden death late after repair remains a problem. Ventricular tachycardia (VT)originating in the right ventricular outflow tract (RVOT)is a well described, clinically important finding following surgicaJ repair of tetralogy and a number of investigators suggest that this VT plays a critical role in the etiology of sudden death. We report two patients with RVOT VT late after repair of tetralogy who underwent successful radiofrequency ablation of their tachycardia.
Intravascular Extraction of Chronic Pacemaker Leads: Efficacy and Follow‐Up
Authors: COLAVITA PAUL G. , ZIMMERN SAMUEL H. , GALLAGHER JOHN J. , FEDOR JOHN M. , AUSTIN W. KENNETH , SMITH HEIDI J.
Published: July 2006

Extraction of chronic pacemaker leads has been recommended for infections, prevention of venous thrombosis, migration, and possible perforation. Success with constant traction techniques has been variable, and the cost and morbidity of open chest surgical procedures are prohibitive. Efficacy of a new system for lead extraction using intravascular techniques was analyzed. The system (Cook Pacemaker) uses a locking stylet, which is secured at the distal electrode by counterclockwise rotation to reinforce the lead and facilitate traction, and dilator sheaths that are used to free the lead from adhesions in the venous system. In a series of 56 patients (ages 19–88)who presented for lead extraction because of erosion (5), infection (14), lead replacement (35), or other (2), 86 leads were extracted. Thirty‐two were atrial leads and 54 ventricular; 23 had active fixation and 63 passive. Average duration of implant was 58 ±42 months (range 1–264). Eighty‐four leads were totally removed and two partially removed. For these two leads, the distal tip was not removed; in both cases the locking stylet was not secured at the distal electrode due to obstruction within the lead. Two patients developed arm edema following the procedure, which resolved with elevation. One patient developed a subclavian thrombosis, which resolved with warfarin anticoagulation. Four patients have expired due to unrelated causes. In conclusion, this intravascular approach for extraction of chronic leads is effective, and the procedure is safe when performed by experienced personnel.
The Dotter Retriever and Pigtail Catheter: Efficacy in Extraction of Chronic Transvenous Pacemaker Leads
Authors: ESPINOSA RAÚL E. , HAYES DAVID L. , VLIETSTRA RONALD E. , OSBORN MICHAEL J. , McGOON MICHAEL D.
Published: July 2006

Several techniques exist for percutaneous extraction of chronic pacemaker leads. To establish the efficacy of the Dotter retriever and pigtail catheter, we reviewed the removal of 59 endocardial pacemaker leads in 42 patients (mean age 71 years). The mean duration of lead implantation was 44 months (range 1–169 months). Thirty‐two leads were withdrawn with simple traction alone, and five leads were abandoned when traction failed. The remaining 22 leads were manipulated with a Dotter retriever or pigtail catheter, or both. Twelve leads were dislodged from the endocardium with simple traction (10)or with traction transmitted through an entwining pigtail catheter (2), but they could not be fully withdraivn. Eleven of these leads (92%)were then successfully extracted with the Dotter retriever. Seven of the remaining 10 leads were successfully disJodged and removed by the Dotter retriever. Overall, 9 of 12 leads (75%)that could not be dislodged from the endocardium with simple traction were removed with a Dotter retriever or pigtail catheter, or both. Three patients in whom no catheter method worked required thoracotomy for removal of infected leads. No complications resulted from use of the Dotter retriever or pigtail catheter. We conclude that the Dotter retriever and pigtail catheter have moderate efficacy for dislodging chronic endocardial leads. Once mobilized, however, the leads can be withdrawn with great success with the Dotter retriever. Newer technology should not result in the abandonment of this proven technique.
Catheter Ablation Induced Reversal of Chronic Left Ventricular Dysfunction in Permanent Junctional Tachycardia
Authors: SAOUDP NADIR , KIRKORIAN GILBERT , ATALLAH GEORGES , DESSEIGNE PIERRE , CHAMPAGNAC DIDIER , TOUBOUL PAUL
Published: July 2006

Three patients with the permanent form of junctional tachycardia are reported. All had a normal cardiac function when the rhythm disorder was discovered. The basis for tachycardia in the three cases was atrioventricular junctional reentry whose retrograde limb was a concealed posteroseptal accessory pathway. Because of the development of heart failure over the years, one patient had His bundle ablation combined with pacemaker insertion, and the others underwent catheter ablation of the accessory pathway. Reversal of left ventricular involvement, as ossessed by chest X ray and echocardiography was noted in every patient. Ejection fraction in one patient, measured by radionuclide angiography, returned to normal 3 months later. Thus catheter ablation of permanent junctional tachycardia can effectively suppress rhythmic cardiomyopathy.
The Right Atrial Free Wall: An Alternative Pacing Site
Authors: JAMIDAR HUMAYUN , GOLI VASU , REYNOLDS DWIGHT W.
Published: July 2006

A major advantage of active fixation permanent pacing leads is their ability to be actively attached in areas where conventional passive fixation leads cannot be. In a review of records of 134 consecutive patients requiring dual chamber pacing, all of whom received active fixation atrial leads, 56 had right atrial appendage (AA) pacing and 78 had right atrial free‐wall (AFW) pacing. Acute electrical parameters including sensed P wave amplitude (AA ‐ 5.6 ± 2.3 mV. AFW = 5.5 ± 2.3 mV), slew rate (AA = 1.21 ± 0.77 V/sec, AFW = 1.20 ± 0.74 V/sec), stimulation thresholds (voltage and current) including rheobase voltage (AA = 0.6 ± 0.2 V, AFW ‐ 0.6 ± 0.2 V), and pacing impedance (AA = 516 ± 89 ohms, AFW = 504 ± 84 ohms) were similar in both groups. There were two dislodgements fatrial appendage group) and no episodes of clinically important perforation or diaphragmatic stimulation. The free wall of the right atrium appears to he an excellent alternative pacing site to the appendage.
Use of a Dual Chamber Pacemaker with a Novel Fallback Algorithm as an Effective Treatment for Sick Sinus Syndrome Associated with Transient Supraventricular Tachyarrhythmia
Authors: MAYUMI HISANORI , UCHIDA TAKAYUKI , SHINOZAKI KEIICHI , MATSUI KANZI
Published: July 2006

A dual chamber pacemaker having a fallback (FB) mode was utilized in nine patients with sick sinus syndrome (SSS) associated with transient supraventricular tachyarrhythmia (atrial fibrillation [Af] in three patients, atrial flutter [AF] in two, and paroxysmal atrial tachyarrhythmia [PAT] in four). Various degrees of abnormality of atrioventricular (AV) conduction were observed at the time of pacemaker implantation in five patients. In this pacemaker, a DDD mode was active during sinus rhythm, but the mode changed, through a given cycle of high rale tracking at an upper rate limit (VRL), to VDI only during intrinsic atrial rate increases that were either normally or abnormally above the URL. The VDI mode automatically returned to DDD when the atrial rate fell below the URL. At follow‐up periods of 7–12 months, this pacemaker appeared to be especially effective in those SSS patients with transient Af or AF. In the SSS patients with PAT, however, the FB mode was not active because the PAT rhythm was conducted to the ventricle without block (1:1 conduction) and thus the given cycles of ventricular tracking at the URL did not occur. From the repetitive FB starting tests that were performed during an Af period in one patient with transient Af, a 2:1 point setting of a given URL plus 30–50 ppm was required to quickly start the FB algorithm. Moreover, an atrial sensitivity setting that was less than half of the P wave amplitude was desirable. These results suggest that, when properly set, the DDD plus FB mode is useful in a SSS patient with transient supraventricular tachyarrhythmia when a significant degree of AV block is present.
Delayed Effects of Radiofrequency Energy on Accessory Atrioventricular Connections
Authors: LANGBERG JONATHAN J. , BORGANELLI S. MARK , KALBFLEISCH STEVEN J. , STRIGKBERGER S. ADAM , GALKINS HUGH , MORADY FRED
Published: July 2006

The purpose of this study was to determine the incidence and characteristics of delayed effects on conduction through accessory atrioventricular (AV) connections after apparently successful attempts at radiofrequency catheter ablation. Among 450 patients who had 471 accessory AV connections, the ablation procedure was unsuccessful in 26 patients (6%), as defined by persistent conduction through the accessory AV connection 60 minutes after the final application of radiofrequency energy. In 6/26 unsuccesfully treated patients (24%), conduction through the accessory AV connection disappeared on a delayed basis. At least once during the ablation procedure, conduction through each of these 6 accessory AV connections was transiently eliminated for 10 seconds to 60 minutes. Five of these accessory AV connections were left‐sided and one was posteroseptal; one was concealed and five were manifest. Conduction through the accessory AV connection disappeared on a delayed basis 6–18 hours after the ablation procedure in 4 patients, and at some time between 1–5 days or 1–60 days in the other 2 patients. In 2 patients, the delayed effect was only transient, while in 4 patients, conduction through the accessory AV connections did not return during 5–23 months of follow‐up. In conclusion, up to 15% of patients who undergo an apparently unsuccessful attempt at radiofrequency ablation of an accessory AV connection may later manifest a permanent loss of conduction through the accessory AV connection.
Body Surface Laplacian Mapping of Cardiac Excitation in Intact Pigs
Authors: HE BIN , KIRBY DEBRA A. , MULLEN THOMAS J. , COHEN RICHARD J.
Published: July 2006

Relating body surface electrocardiographic signals to regional myocardial events has been a major effort in cardiac electrophysiology. Convenlional electrocardiographic means do not provide sufficient spatial resolution to resolve distributed cardiac electrical activity. The purpose of this investigation was to evaluate and study the validity of a new technique—body surface Lapiacian mapping—in a well‐controlled experimental setting, and to test the hypothesis that the body surface Laplacian map (BSLM) can resolve normal and abnormal ventricular depolarization patterns and localize the initial site of ventricular depolarization with high spatial resolution. In this study. BSLMs were constructed from direct measurements of the surface Laplacian of the body surface potentials using an array of 64 concentric bipolar Laplacian electrodes. BSLMs were compared to body surface potential maps (BSPMs) during normal and ectopic ventricular activation in intact anesthetized pigs. The BSLM displayed highly localized images of cardiac electrical activity, indicating its ability to resolve myacardiai events. The BSLM in pigs identified the pacemaking focus overlying the known location of ihe epicardial pacing electrode, and imaged the activation sequence associated with exogenous ventricular pacing. In contrast, in all cases the BSPM revealed a diffuse distribution of activity over the chest. The present results suggest that the BSLM provides sufficient spatial resolution to relate body surface recordings to regional myocardial events and is able to detect ventricular depolarization patterns with greater resolution than the conventional BSPM.
Sudden Death in Idiopathic Dilated Cardiomyopathy: Role of Ventricular Arrhythmias
Authors: LARSEN LANCE , MARKHAM JAY , HAFFAJEE CHARLES L
Published: July 2006

Sudden cardiac death (SCD) is associated with idiopathic congestive cardiomyopathy (IDCM) and most commonly is due to ventricular tachyarrhythmias. The recurrence rate of SCD in the absence of specific therapy is thought to be around 20%–30% per year. Asymptomatic and symptomatic ventricular arrhythmias are common in patients with IDCM and the direct causal link of such arrhythmias with SCD in IDCM patients remains to be established. Furthermore, therapy directed at suppressing these ventricular arrhythmias has not been shown to decrease the incidence of SCD. Various approaches such as ambulatory monitoring, eiectrophysiological testing, signal‐averaged electrocardiogram, and hemody‐namics have met with variable success in identifying patients prone to SCD. Additionally, therapeutic approaches to prevent SCD in IDCM patients have produced equivocal results. This article reviews the published studies addressing the causal link of ventricular arrhythmias to sudden death in patients with IDCM and the attempts to decrease the incidence of sudden.
Left Ventricular Malposition of a Transvenous Cardioverter Defibrillator Lead: A Case Report
Authors: SPLITTGERBER FRED H. , ULBRICHT LUDGER J. , REIFSCHNEIDER HANS‐J. , PROBST HERBERT , GÜLKER HARTMUT , MINALE CARMINE
Published: July 2006

A case of left ventricular endocardial malposition of a transvenous implantabie cardioverter defibrillator (ICD) lead through a patent foramen ovale is presented. Diagnostic modalities include lateral chest radiography, echocardiography, and electrocardiographic analysis during lead placement. The operative therapy consists of open lead replacement. Measures to avoid lead misplacement are suggested.
Potential Hazards of Fixed Gain Sensing and Arrhythmia Reconfirmation for Implantable Cardioverter Defibrillators
Authors: SINGER IGOR , ADAMS LESA , AUSTIN ERLE
Published: July 2006

Appropriate sensing of ventricular tachycardia (VT) and ventricular fibrillation (VF)is of paramount importance for safety of patients with implanted cardioverter defibrillators (ICDs). Recently, the GuardianR ATP 4210, a new third generation ICD that uses programmable but fixed sensing during sinus rhythm and doubles its sensitivity settings when VF is detected, to a maximum programmable sensitivity of 1 mV, has been tested in phase I and II clinical trials. A reconfirmation algorithm of this ICD confirms the presence of VT or VF prior to therapy. This case report describes undersensing of VF in a patient with the GuardianR ATP 4210 at the maximum programmed sensitivity of 1 mV. Inappropriate episodes of asystole and prolonged bradycardias were also observed in this patient due to shortcomings in the reconfirmation algorithm design. Reoperation was required, with positioning of a new endocardial sensing lead to correct the undersensing of VF. This, however, did not correct asystolic pauses following antitachycardia pacing or spontaneous tachycardio termination prior to therapy. This case report highlights the hazards of fixed gain sensing for implantable ICDs and a potential limitation of a specific tachyarrhythmia reconfirmation algorithm used in this device.
Influence of Internal Current and Pacing Current on Pacemaker Longevity
Authors: SCHUCHERT ANDREAS , KUCK KARL‐HEINZ
Published: July 2006

The effects of lower pulse amplitude on battery current and pacemaker longevity were studied comparing the new, small‐sized VVI pacemaker, Minix 8341, with the former model, Pasys 8329. Battery current was telemetrically measured at 0.8. 1.6, 2.5, and 5.0 V pulse amplitude and 0.05, 0.25, 0.5, and 1.0 msec pulse duration. Internal current was assumed to be equal to the battery current at 0.8 V and 0.05 msec. Pacing current was calculated subtracting internal current from battery current. The Minix pacemaker had a significantly lower battery current because of a lower internal current (Minix: 4.1 ±0.1 μA; Pasys: 16.1 ± 0.1 μA); pacing current of both units was similar. At 0.5 msec pulse duration, the programming from 5.0‐2.5 V puise amplitude resulted in a greater relative reduction of battery current in the newer pacemaker (51% vs 25%). Projected longevity of each pacemaker was 7.9 years at 5.0 V and 0.5 msec. The programming from 5.0–2.5 V extended the projected longevity by 2.3 years (Pasys) and by 7.1 years (Minix). The longevity was negligibly longer after programming to 1.6 V. Conclusion: Extension of pacemaker longevity can be achieved with the programming to 2.5 V or less if the connected pacemakers need a low internal current for their circuitry.
Acute Pericarditis Resulting From an Endocardial Active Fixation Screw‐In Atrial Lead
Authors: GREENE TREVOR O. , PORTNOW ARTHUR S. , HUANG SHOEI K. STEPHEN
Published: July 2006

We examined the occurrence of acute pericarditis after pacemaker implantation in 123 consecutive patients (61 males, 62 females, ages 17–87 years) in whom a newer atrial active fixation bipolar lead was inserted endocardially in the right atrium for dual chamber pacing. The atrial leads were positioned to obtain the best possible pacing and sensing thresholds, after an initial attempt was made for insertion into the right atrial appendage or medially into the right atrial septum. Six patients (4.9%) developed acute symptomatic pericarditis with effusion within 24 hours of implantation. Of these six patients, four had leads screwed into the lateral waH. and the other two had leads placed in the anterolateral wall. The lead implantation parameters between patients with pericarditis and those without did not show any significant difference in the atrial P wave amplitude (2.3 ± 0.4 vs 2.9 ± 0.9 mV), pacing threshold (1.1 ± 0.2 vs 1.1 ± 0.4 V), or resistance (524 ± 112 vs 480 ± 94 ohms). All symptomatic patients were treated with nonsteroidal anti‐inflammatory drugs with symptoms resolving in 1–2 weeks. We condude that: (1) a significant number of patients (4.9%) developed acute symptomatic pericarditis after insertion of this type of atrial fixation lead: (2) because of the lead design, the implantation parameters coud not be taken to predict the occurrence of pericarditis: and (3) caution should be taken for the insertion of this lead into the thin atrial wall.
Catheter Induced Mechanical Stunning of Accessory Pathway Conduction: Useful Guide to Successful Transcatheter Ablation of Accessory Pathways
Authors: TAI YAU‐TING , LEE KATHY LAI‐FUN , LAU CHU‐PAK
Published: July 2006

Established electrophysiological criteria indicating anatomical proximity to an accessory pathway include early ventricular or atrial activation during antegrade or retrograde accessory pathway conduction, recording of accessory pathway potentials, and pace map concordance. This article describes two cases of RF catheter ablation of accessory pathways, during which positioning of the mapping catheter at specific sites on the endocardial aspect of the atrioventricular annulus led to prolongation of accessory pathway refractoriness and/or slowing of conduction. HF energy application at these sites successfully abolished accessory pathway conduction. When observed on an “intentional” basis during catheter mapping, catheter induced stunning of accessory pathway conduction provides evidence of satisfactory electrode‐tissue contact in addition to anatomical proximity, and may give additional predictive value to successful transcatheter accessory pathway ablation.
Long‐Term Performance of Endocardial Pacing Leads
Authors: HELGUERA MARCELO E. , MALONEY JAMES D. , PINSKI SERGIO L. , WOSCOBOINIK JAVIER R. , WILKOEE BRUGE L. , CASTLE LON W.
Published: July 2006

To assess the performance of endocardial pacemaker leads and to identify factors associated with structural lead failure, medical records of 2,611 endocardial pacing leads (in 1, 5W patients) implanted between 1980 and 1991, having at least 1 month of follow‐up, were reviewed. Leads without structural failure had normal function at the last follow‐up date, or were discontinued for reasons other than structural failure (patient death, infection, dislodgment, lead‐pacemaker incompatibility, operative complication, or abandonment by telemetry not related to failure). Leads with suspected structural failures were invasively or noninvasively disconnected because of clinical malfunction (loss of capture or sensing, oversensing, elevated thresholds, or skeletal muscular stimulation). Leads with verified structural failures met the criteria for suspected lead failure and also had a visible defect seen in the operating room or on chest roentgenograms, a change in the impedance interpreted by the physician as lead disruption, or a manufacturer's return product report that confirmed structural failure. Variables analyzed included patients’ age and gender, paced chamber, venous access, insulation materials, fixation mechanism, coaxial design, polarity, and different lead models. The cumulative lead survival at 5 and 10 years were 97.4% and 92.9%, respectively, for suspected failures; and 98.7% and 97.3%, respectively, for verified failures. Leads in older patients (≥ 65 years old), and leads in atrial position had fewer verified failures (P = 0.014 and P = 0.007, respectively). Unipolar leads also tended to perform better according to the verified definition (P = 0.07). The lead Medtronic 4012 had more suspected (P < 0.05) and more verified failures (P < 0.01), the lead CPI 4010 had more verified failures (P < 0.05) than the entire group of ventricular leads. Conclusions: Endocardial pacing leads implanted in atrial position, and implanted in older patients (> 65 years old) seems to have better long‐term survival. Some lead models (Medtronic 4012 and CPI 4010) had poor survival rates, that could not be explained by the analyzed variables. The expected performance of endocardial pacing leads varies according to how failure is defined.
Radiofrequency Catheter Atrioventricular Node Ablation in Patients with Permanent Cardiac Pacing Systems
Authors: CHANG ANTHONY C. , McAREAVEY DOROTHEA , TRIPODI DOROTHY , EANANAPAZIR LAMEH
Published: July 2006

Following successful BF ablation of the atrioventricular node (AVN), temporary pacing is necessary prior to insertion of a permanent pacemaker. The risks and inconvenience of temporary pacing could be avoided if a permanent pacemaker is already in place. This study reports the feasibility of RF ablation of the AVN in 27 patients (age 55 ± 17 years, 15 males) with hypertrophic cardiomyopathy and pacemakers, Indications for AVN ablation were drug refractory atrial fibrillation in 24 patients, and rapid AVN conduction preventing septal pre‐excitation by DDD pacemaker, inserted for relief of left ventricular outflow obstruction, in three cases. Sixteen patients had DDD devices and 11 patients had VVI devices. During RF ablation, each pacemaker was programmed to VVI at 50 beats/min. The ablation catheter was manipulated with fluoroscopic control to avoid close contact with or disturbance of the pacing leads. In 16 patients, RF ablation was performed immediately following pacemaker implantation but in the remaining patients, the AVN was ablated 6–32 months after pacemaker implantation. The power applied was 25–50 watts for a duration of 15–60 seconds. AV block was achieved in all cases but required 34 ± 36 applications for 16.5 ± 17.8 min/case. RF ablation consistently caused reversion to magnet rate in one patient and temporarily inhibited appropriate pacemaker discharge in another. However, no other pacemaker or lead malfunction was detected so that temporary pacing was not required in any case. At 6 ± 3 months follow‐up, all pacemakers were functioning normally without alteration in pacing parameters from baseline. Thus. RF ablation of the AVN can be performed safely in the presence of a recently implanted permanent pacemaker, without temporary pacing.
Bradycardia Dependent QT Prolongation and Ventricular Fibrillation Following Catheter Ablation of the Atrioventricular Junction witb Radiofrequency Energy
Authors: PETERS RENE H.J. , WEVER ERIC F.D. , HAUER RICHARD N.W. , WITTKAMPF FRED H.M. , de MEDINA ETIENNE O. ROBLES
Published: July 2006

Recurrent ventricular fibrillation was observed in a 67‐year‐old woman following catheter ablation of the AV junction using radiofrequency energy. This serious complication has been reported following direct current energy ablation of the AV junction, but not after using radiofrequency energy. This life‐threatening arrhythmia seemed pause and bradycardia dependent. It was followed by QTc prolongation of the QRS escape rhythm 1 day after the procedure. Ventricular arrhythmias were suppressed by rapid ventricular pacing.
Computer Model of the Atrioventricular Node Predicts Reentrant Arrhythmias
Authors: LEFFLER CHRISTOPHER T. , SAUL J. PHILIP
Published: July 2006

Introduction: Following atrial premature beats, the AV node may exhibit sustained reentrant tachyarrhyth‐mias, isolated echo beats, or discontinuities in the recovery curve (the plot of conduction time versus atrial cycle length). A computer model was used to examine the hypothesis that spatial variation of AV nodal passive electrical resistance may account for these phenomena. Methods and Results: A computer model of a rectangular lattice of elecirotonically linked elements whose ionic kinetics simulated nodal ionic flux was developed. the model showed that there exists a resistance value that minimizes the effective refractory period, because high resistance prevents depolarization of distal elements, while low resistance allows leakage of depolarizing current by electrotonic transmission, preventing activation of proximal elements. High resistances stabilized reentry by slowing conduction. Simulations incorporating equal resistance values between elements predicted increased AV nodal conduction times with increasing prematurity of atrial impulses. A model with a gradual change in resistance between fibers produced discontinuities and tachycardia, but not both simultaneously. Uniform anisotropy produced preferential transverse block, leading to echo beats and “fast‐slow” tachycardia, but not recovery curve discontinuities. Nonuniform anisotropy could produce reentry, but tachycardia often occurred without discontinuities. Dividing the lattice into two electrotonically linked parallel pathways with different resistance values (“dual pathway model”) predicted recovery curve discontinuities, echo beats, and tachycardia. At critical atrial cycle lengths, only the (high resistance) slow pathway conducted antegradely, while the fast pathway conducted retrogradely, to generate the typical “slow‐fast” tachycardia. Responses of the dual pathway model to ablation were consistent with clinical data, including the previous observation of a decrease in fast pathway effective refractory period after slow pathway ablation. Conclusion: Differences in passive electrical resistance of electrotonically linked dual pathways within the AV node may account for functional longitudinal dissociation, reentrant arrhythmias, and responses to catheter ablation therapy.
Comparative Thrombogenicity of Pacemaker Leads
Authors: PALATIANOS GEORGE M. , DEWANJEE MRINAL K. , PANOUTSOPOULOS GEORGE , KAPADVANJWALA MANSOOR , NOVAK STANA , SFAKIANAKIS GEORGE N.
Published: July 2006

To evaluate the throm bogenicity of transvenous silicone and polyurethane pacemaker leads, 9 of 12 anesthetized Yorkshire pigs (27–32 kg) were implanted with silicone (n = 5) or polyurethane (n = 4) pacemaker leads via a femoral vein. The remaining three pigs served as controls. All 12 pigs were injected with autologous indium‐111 labeled platelets (300–420 μCi) 24 hours before anesthesia induction. The pigs were monitored for 3 hours under a gamma camera. Radioactivity in blood and lead segments was measured with a gamma counter. Platelet deposits were denser on silicone leads (441.58 ± 915.0 to 2.19 ± 2.07) than on polyurethane leads (1.21 ± 1.33 to 0.27 ± 0.14) (P > 0.05). Denser platelet deposits were detected at the tip of all leads. Density of platelet deposits declined from tip to distal segments in silicone leads. The percentage of injected platelet radioactivity in the lungs of pigs with either silastic leads (12.9 ± 2.3%) or polyurethane leads (10.1 ± 2.2%) was higher than in the controls (4.6 ± 0.5%) (P < 0.05). This difference indicates thrombus formation and embolization in the lungs early after lead implantation. Thrombogenicity of polyurethane leads may be lower than that of silicone leads.
Effect of Beta‐Adrenergic Stimulation on the QT Interval of Children with Syncope
Authors: BALAJI SESHADRI , OSLIZLOK PAUL C. , McKAY CHRISTINE A. , ALLEN MARY C. , CASE CHRISTOPHER L. , HEWETT KENNETH W. , GILLETTE PAUL C.
Published: July 2006

The effect of intravenous bolus doses (0.25. 0.5. 1.0 fig) of isopwterenol on the QT and BR intervals was reviewed in a group of 34 children undergoing autonomic testing for svncope. Twenty‐one patients had a positive orthostatic test and 13 were negative. The two groups (positive and negative) were compared Baseline QT and RR intervals were similar. The RR interval was shortened by isoproterenol in both groups Isoproterenol shortened the QT interval in the negative group (as seen in normal persons), but produced QT prolongation in the positive group, although neither reached statistical significance when compared to baseline within the respective group. Comparing the values for RR and QT at each dose of isoproterenol (including baseline) between the two groups showed a significant difference in the QT interval after the 1.0‐fxg dose of isoproterenol. Thus children with orthostatic positive neurocardiogenic syncope showed a different QT response to fi‐adrenergic stimulation. This lends support to the theory of altered /3‐adrenergic sensitivity being present in children with neurocardiogenic syncope.