bluuebunny/crossref_metadata_2025 huggingface dataset:
Electronic Article Surveillance: A Possible Danger for Pacemaker Patients
Authors: DODINOT BERNARD , GODENIR JEAN‐PHILIPPE , COSTA ALVARO BARROS , ZELLER CLAUDE , BROSCHART MARK
Published: July 2006

In order to evaluate if antitheft devices commonly designed as electronic article surveillance (EAS) systems can be dangerous for pacemaker patients, in vitro and in vivo studies were made in close cooperation between a pacemaker center and an EAS designer. Three types of EAS radiation including radiofrequency, magnetic, and pulsed electromagnetic fields were applied to various pacemakers. The in vitro study consisted of exposing to the EAS fields 28 pacemakers connected to unipolar leads. Radiofrequency fields and pulsed electromagnetic fieids evoked minor effects and no prolonged inhibitions. When exposed to magnetic fields, most of the pacemakers switched to “fixed rate” pacing, but inhibitions were observed in 13 pacemakers exposed to 300 Hz, and in 14 pacemakers exposed to a 10‐kHz magnetic field when they were moved at cardiac frequencies within the fields. The in vivo study was made on 32 volunteers treated by 26 different pacemakers: 22 single chamber and ten dual chamber. All patients had been monitored in the pacemaker clinic and pacemakers were working well. Radiofrequency and pulsed electromagnetic fields did not affect the pacemaker function. Magnetic interference evoked prolonged inhibition of seven out of the ten dual chamber pacemakers, causing brief asystole in patients being continually paced. None of the dual chamber pacemakers incorporated “safety stimulation intervals” after ventricular bianking. The EAS artifact was sensed after the ventricular blanking causing a cross‐talk ECG pattern. No reprogramming was induced by the electromagnetic fields. This experience demonstrates that certain EAS may be dangerous for pacemaker patients. Following this cooperative study a pacemaker safe EAS circuit delivering short bursts of magnetic fields has been designed.
Successful Radiofrequency Energy Ablation of Automatic Junctional Tachycardia Preserving Normal Atrioventricular Nodal Conduction
Authors: EHLERT FREDERICK A. , GOLDBKRGER JEFFREY J. , DEAL BARBARA J. , BENSON D. WOODROW , KADISH ALAN H.
Published: July 2006

Automatic junctional tachycardia is frequently refractory to medical management and difficult to treat with nonpharmacoJogical methods. A 12‐year‐old female with symptomatic, refractory automatic junctional tachycardia is reported. Earliest atrial activation during supraventricular tachycardia was in the posterior portion of the intraatrial septum. The patient underwent electrophysiological study and successful radiofrequency current ahiation of the ectopic automatic focus within the atrioventricuiar junction. Normal atrioventricular junctional conduction was maintained, and at 7‐month foJlow‐up the patient has been free of tachycardia.
Radiofrequency Ablation of Left‐Sided Accessory Atrioventricular Pathways in Patients with Unusual Coronary Sinus
Authors: CHIANG CHERN‐EN , CHEN SHIH‐ANN , TSANG WING‐PING , HSIA CHIH‐PING , WANG DER‐CHIN , CHIOU CHEUEN‐WONG , YANG CHIN‐RUEY , WANG SHIH‐PU , CHIANG BENJAMIN N. , CHANG MAU‐SONG
Published: July 2006

Four patients with left‐sided accessory pathways (APs)and unusual coronary sinus (CS)received radiofrequency ablation. Unusual CS included occlusion of CS (patient 1), acute anguJation of proximal CS (patients 2 and 3), and narrowing of CS orifice and proximal segment (patient 4). CS catheterization and AP mapping along the CS could not be performed in the four patients. Radiofrequency ablation by left ventricular retrograde technique for the manifest left posteroseptal AP (patient 1), concealed left posterior AP (patient 2), and transseptai left atrial technique for the manifest left posteroseptal AP (patient 3)and manifest left posterior AP (patient 4)were performed successfully without CS catheter guidance. This study suggests that radiofrequency ablation of left‐sided AP with unusual CS is feasible by some special techniques.
Spatial Differences of the Duration of Ventricular Late Fields in the Signal‐Averaged Magnetocardiogram in Patients with Ventricular Late Potentials
Authors: WEISMÜLLER PETER , RICHTER PETER , ABRAHAM‐FUCHS KLAUS , HÄRER WOLFGANG , SCHNEIDER SIEGFRIED , HÖHER MARTIN , KOGHS MATTHIAS , EDRICH JOCHEN , HOMBACH VINZENZ
Published: July 2006

Magnetocardiography (MCG) allows one to noninvasively localize cardiac electrical activity in three dimensions. It was the purpose of this study to obtain information about the spatial variations of signal‐averoged ventricular Jate magnetic fields recorded by a biomagnetic multichannel system. Biomagnetic signals of 170–600 heart cycles obtained hy the 37‐channel system KRENIKONR (Siemens Medical Engineering Group) were simultaneously averaged in all channels. The absolute values of the filtered signals (digital, bidirectional, four‐pole butterworth, bandpass filter [3‐dB range, 40–250 Hz]) were calculated in each channel. The noise level was determined within the TP segment. The onset of the terminal low amplitude signals (TLAS) was defined when the signals became lower than 1/23 of Rmaxof the QRS complex for the channel with the largest filtered QRS complex after filtering. The TLAS ended when the signal was lower than twice the standard deviation (2 sigma) above the mean noise level. Ventricular late fields were defined as present when the TLAS had a duration of more than 39 msec. In this study, five patients with ventricular late potentials (four with sustained ventricular tachycardia) and three healthy individuals were examined. Ventricular late fields were detected in the patient group in 2–15 MCG channels with a mean length of 49.6 msec (43–60 msec). The spatial distribution of the ventricular late fields was consistently found to exhibit maximum duration in a certain area. In the normal subjects no ventricular late fields were detected. Thus, MCG is able to detect ventricular late fields and their spatial variations. In addition to the information obtained hy signal averaging from the surface ECG, averaging of biomagnetic signals with a multichannel device can reveal spatial inhomogeneity of delayed myocardial excitation.
The Role of an Engineering Oriented Medical Research Group in Developing Improved Methods and Devices for Achieving Ventricular Defibrillation: The University of Missouri Experience
Authors: SCHUDER JOHN C.
Published: July 2006

Physical scientists and engineers have played important roles in helping to expand our understanding of the factors that influence the defibrillation process and in developing improved methods and devices for achieving cardiac ventricular defibrillation. The long‐term experience of one engineering oriented group, based in a clinical department of a medical school, is summarized. Emphasized are the features of a series of research defibrillators that facilitated the generation of an extensive experimental database from studies in dogs and calves, the development of the first automatic implantable defibrillator to be successfully used in dogs, and studies that furnished the rationale for the widespread use of the uniphasic truncated exponential waveform and for the increasing interest in a variety of biphasic and multiphasic waveforms. Also considered are studies concerning the scaling of the defibrillatory shock with subject size and the role of compound units, defibrillation threshold, and contour graphs in the presentation and interpretation of data.
Initial Experience with a New Transvenous Defibrillation System
Authors: TRAPPE HANS‐JOACHIM , KLEIN HELMUT , FIEGUTH HANS‐GERD , KIELBLOCK BIRGIT , WENZLAFF PAUL , LICHTLEN PAUL R.
Published: July 2006

The clinical efficacy and safely of a new bidirectional transvenous defibrillation endocardial lead system (ELS) was studied in 39 patients with ventricular tachycardia (VT) or fibrillation (VF). There were 28 patients with coronary disease and 11 patients with nonischemic VT/VF. Fourteen patients received the ELS combined with antitachycardia pacing devices (Ventak PRx 1700, CPI) and 25 patients with the Ventak P or P2 (CPI). Implantation of the ELS was attempted in 47 patients. Intraoperatively, the mean defibrillation threshold (DFT) was > 25 joules in five patients and no reliable ELS position was found in three other patients. These eight patients underwent thoracotomy and epicardial leads implantation. The mean DFT was ≤ 20 jouJes in all 39 patients and the mean DFT was 18 joules. During the mean follow‐up of 8 ± 2 months two patients (5%) died suddenly. Complications occurred in two patients (5%).
Conversion Rates of Induced Versus Spontaneous Ventricular Tachycardia by a Third Generation Cardioverter Defibrillator
Authors: PORTERFIELD JAMES G. , PORTERFIELD LINDA M. , SMITH B.A. , BRAY LOUISE , VOSHAGE LYNNETT , MARTINEZ ANITA ,   VENTAK PRx PHASE I INVESTIGATORS
Published: July 2006

Seventy consecutive patients received the first VENTAK PRx pulse generators (Cardiac Pacemakers, Inc.) implanted in the United States. This multiprogrammable device has therapeutic options that include: (1) antitachycardia pacing; (2) low energy cardioversion; (3) defihrillation shocks; and (4) bradycardia pacing. There were 60 males and 10 females with a mean age of 65.3 ± 9.4 years. The anatomical diagnoses were coronary artery disease in 55 patients, cardiomyopathy in 7 patients, congenital heart disease in 2 patients, and miscellaneous disease in the remaining 6 patients. Thirty‐six percent had a history of sudden cardiac death and 90% had documented monomorphic ventricular tachycardia. The mean ejection fraction was 32.7%± 12.2%. Thirty‐three (49.3%) had an ejection fraction ≤ 30%. Electrophysiological testing was done preimplant, predischarge, and 1 to 2 months postimplant to define a specific electrical therapy and evaluate the efficacy of the device. Two hundred ninety‐three of 367 (80%) episodes of induced ventricular tachycardia were successfully terminated by the VENTAK PRx programmed for antitachycardia pacing. There were 1,794 total therapy episodes for spontaneous ventricular tachycardia; 91% (1,641 episodes) were terminated by antitachycardia pacing and 153 episodes were converted by shocks during a minimal 6‐month follow‐up per patient. We conclude that documentation of a successful antitachycardia pacing modality in the electrophysiology laboratory predicts conversion of spontaneous episodes of ventricular tachycardia. Furthermore, antitachycardia pacing by the VENTAK PRx can terminate the majority of episodes of ventricular tachycardia.
Device Use Patterns and Clinical Outcome of Implantable Cardioverter Defibrillator Patients with Moderate and Severe Impairment of Left Ventricular Function
Authors: MEHTA DAVENDRA , SAKSENA SANJEEV , KROL RYSZARD B. , JOHN THAMPI , SAXENA AMARKANTH , RAJU RAMESH , KAUSHIK RAJ , KARANAM RAVINDRA
Published: July 2006

The beneficial effects of implanted cardioverter defibrillator (ICD) therapy in patients with malignant ventricular tachyarrhythmias and variable degrees of left ventricular (LV) dysfunction are debated. ICD use and patient survival were examined in 128 patients with malignant ventricular arrhythmias and moderate or severe LV dys function. Group I included 64 patients with moderate LV dysfunction (LV ejection fraction of > 30%) and group H, 64 patients with severe LV dysfunction (LV ejection fracfion of ≤ 30%). Follow‐up period ranged from 1 to 78 months. The two groups were similar in age, incidence of coronary artery disease and presenting arrhythmia. The mean LV ejection fraction in group I was 44%± 8% and group II was 22%± 5% (P < 0.0001). At 4 years of follow‐up, 66% of patients from group I and 62% from group II (P = NS) had ICD activation for presumed ventricular tachyarrhythmia. Survival was calculated using actuarial analysis. Arrhythmic or sudden death mortality at 4 years of follow‐up was 4% in group I and 7% in group II (P = NS). Cardiac mortality was for group I, 7% (P < 0.05), 12% (fP < 0,01), 15% (P < 0.01), and 15% (P < 0.01) for follow‐up years 1, 2, 3, and 4, respectively. For group II, cardiac mortality was 27%, 36%, 41%, and 41% for follow‐up years for 1, 2, 3, and 4, respectively. The majority of cardiac deaths in both groups was observed in the first 2 years of follow‐up. However, in both groups, cardiac mortality was comparable in patients who did (users) and did not (nonusers) experience appropriate ICD shocks. Thus, the incidence of long‐term ICD use is comparable in patients with moderate and severe LV dysfunction. Cardiac mortality is higher in patients with severe LV dysfunction in the first 4 years of follow‐up irrespective of device use. The comparable long‐term clinical outcome of ICD users and non users in patients with moderate or severe LV dysfunction can be related to elimination of arrhythmic mortality. Long‐term patient survival in ICD recipients with severe LV dysfunction remains substantial even at 4 years of follow‐up.
Clinical Outcome Following ICD Removal
Authors: KAWANISHI DAVID T. , SONG SUSAN L. , FURMAN SEYMOUR ,   BILITCH REGISTRY GROUP
Published: July 2006

The Bilitch ICD Registry includes 1,869 patients from 13 medical centers enrolled between March 1982 and April 1992. of these, 95 patients had their units removed and not immediately replaced (77 maIes/18 females mean age 54.9 ± 13.0 years, range 10–76). The mean duration of implanted ICD was 19.5 ± 18.2 months, mean ejection fraction 30.1 ± 11.7%. Coronary artery disease was present in 55 patients, absent in 30, and unknown in 10. The presenting clinical event was sudden death in 35 patients, symptomatic ventricular tachycardia in 34, other causes in 6, and unknown in 20. Reasons for ICD removal were: infection in 33 patients, cardiac transplant in 32, elective in 20, following battery depletion in 7, lead system failure in 2, and inappropriate shock in 1. Of all groups who had their ICD removed, the patients who had removal for cardiac transplantation had the highest incidence of appropriate ICD discharges while the device was implanted (43.8%). Of the 63 nontransplanted patients seven were lost to follow‐up while alive. Of the 56 remaining, 17 died (1 cause unknown, 6 noncardiac, 3 sudden, 1 arrhythmic, 6 nonsudden nonarrhythmic cardiac death), 7 had an ICD reimplanted, and 32 are alive and well without an ICD. Follow‐up for the 32 cardiac transplant patients: 2 were lost to follow‐up while alive, 2 died of nonsudden nonarrhythmic death, and 28 are alive and well. The survival of patients who had their ICD removed and not reimplanted was not different from that of patients who never had their ICD removed up to 2 years. Thereafter, the survival without a device fell below that of those who never had their device removed. Summary: There is a high incidence of ICD discharges in the group undergoing ICD removal for cardiac transplantation. The most common cause of ICD removal was infection. The need for device reimplantation increases at 2 years following device removal. The “elective” device reimplantation does not compromise overall survival.
Defibrillation Thresholds and Perioperative Mortality Associated with Endocardial and Epicardial Defihrillation Lead Systems
Authors: SAKSENA SANJEEV ,   THE PCD INVESTIGATORS,   PARTICIPATING INSTITUTIONS
Published: July 2006

Defibrillation thresholds (DFT) and perioperative mortality were evaluated in 123 patients who had endocardial defibrillation leads implanted in conjunction with the Medtronic model 7216A/7217 (Medtronic, Inc.) cardioverter‐defibrillator (ICD). Clinical variables, implant DFTs, and 30‐day perioperative mortality were compared with 266 patients who had the ICD implanted with epicardial defibrillation leads. The two groups were comparable in age, gender, and incidence of coronary artery disease. New York Heart Association Class I and II were more frequent in patients with endocardial leads (87.7%) as compared to those with epicardial leads (78.8%; P < 0.001). Mean left ventricular ejection fraction was significantly higher in patients with the endocardial lead system (37% vs 33%; P < 0.05). A significant proportion of patients with epicardial lead systems underwent another cardiac surgical procedure at the time of ICD implantation (13.9%) as compared to none in those who had endocardial leads implanted (P < 0.001). All patients with endocardial leads had implantation of triple lead systems as compared to 53.4% with epicardial leads (P < 0.001). The mean DFT at implant was lower in epicardial lead recipients (8.9 J) as compared to endocardial lead recipients (13.3 J; P < 0.001). Perioperative mortality had a significant trend to lower risk for endocardial lead systems (0.8%) as compared to epicardial systems (4.2%; P = 0.07). We conclude that this endocardial lead system has additional electrode and higher defibrillation energy requirements than the epicardial lead systems used with the Medtronic pacemaker ICD. However, the use of endocardial nonthoracotomy defibrillation leads is associated with a markedly reduced perioperative risk of ICD implantation. This could be due to patient characteristics, a less invasive implant procedure, and absence of concomitant cardiac surgery.
Long‐Term Stability of Defibrillation Thresholds with Intrapericardial Defibrillator Patches
Authors: FRAME ROSEMARY , BRODMAN RICHARD , FURMAN SEYMOUR , GROSS JAY , KIM SOO G. , FERRICK KEVIN , ROTH JAMES , HOLLINCER INGRID , FISHER JOHN D.
Published: July 2006

From March 1982 to May 1, 1992, 105 consecutive patients underwent initial implant of cardioverter defibrillators (ICD) at our institution. Twenty‐nine patients (23 male and 6 female, average ejection fraction 32.24%) with ICD systems implanted via thoracotomy and either intra‐ or extrapericardial patches, had one or more revisions including 56 generator changes or staged implant procedures, three patch revisions, one patch lead fracture without revision, and one sensing lead revision. The time between pulse generator revisions averaged 19.5 months. Initial defibrillation threshold mean was 12.8 joules (n = 25); at first revision, 14.46 joules (n = 29), (P = NS); by fifth revision, 15.0 joules (n = 2), (P = NS). One patch was noted to be crinkled at 70 months; one patch had migrated by 39 months, and two patch leads had fractured at the costal margin by 69 and 90 months. One patient with marginal defibrillation thresholds had an additional patch placed at revision to an upgraded ICD unit. Once acceptable defibrillation threshold (DFT) is obtained, the long‐term intrapericardial DFT remains stable unless a specific problem occurs. As a small, nonstatistically significant increase in DFT may occur, caution must be exercised in patients with marginal DFTs.
Decline in Defibrillation Thresholds
Authors: KROLL MARK W. , ANDERSON KENNETH M. , SUPINO C. GERARD , ADAMS THEODORE P.
Published: July 2006

Much research has been done to lower defibrillation thresholds (DFT) through improved waveforms and electrodes. We hypothesized that DFTs are declining steadily, as did pacing thresholds. We performed a meta‐analysis of 105 reports of DFTs from 58 articles and abstracts published from 1973 to 1991. Human, dog, and pig studies were included. Transthoracic and isolated heart studies were excluded. Variables analyzed were: publication year, human study, epicardial electrodes only, multiple pathways (simultaneous or sequential), biphasic wave, subcutaneous patch, coronary sinus electrode, spring‐patch combination, and catheter‐based. DFTs are highly correlated with publication year (P = 0.013) and show an average drop of 0.75 joules/year by a linear univariate analysis. A linear multivariate analysis (r2= 0.51) gave six significant variables for the DFT: epicardial electrodes only, subcutaneous patch, biphasic wave, coronary sinus electrode (each decreased DFTs), and human subject and catheter‐based system (increased DFTs). Conclusions: DFTs have shown a decline over 18 years through electrode and waveform improvements. The practice of making devices with ever increasing energy ratings may eventually merit reexamination. The animal model is a useful predictor for clinical DFTs.
Complications of Implantable Cardioverter Defibrillator Therapy: Follow‐Up of 241 Patients
Authors: GRIMM WOLFRAM , FLORES BELINDA F. , MARCHLINSKI FRANCIS E.
Published: July 2006

In order to determine the incidence of complications of impJantable cardioverter defibrillator (ICD) therapy, 241 patients with a total of 353 ICD implantations were followed for 24 ± 20 months. Complications were defined as any untoward effects experienced by the patient related to the ICD implantation and function or death within 4 weeks of implant or before hospital discharge. During follow‐up, 129 of 241 patients (53%) had a total of 166 complications. An operative procedure was required to correct the complication in 50 of the 241 patients (21%). No patient died intraoperativeiy, but eight patients died within 4 weeks postoperatively or before hospital discharge. ICD infection required removal of the device in 13 patients (5%). Twenty‐six patients (11%) had postoperative respiratory complications. Postoperative bleeding and/or thrombosis occurred in 11 patients (4%). Endocardial lead migration was observed in nine patients (4%) and lead adapter or insulation break occurred in nine patients (4%). Fifty‐four patients (22%) experienced ECC‐documented discharges for non‐VT rhythm. In conclusion, although perioperative mortality in ICD patients is low, the maiority of patients have complications during followup. Recognition of these complications may allow for advances in ICD technology and management strategies to avoid their occurrence.
Implantable Cardioverter Defibrillator Electrogram Recognition with a Multilayer Perceptron
Authors: FARRUGIA STEVEN , YEE HANSEN , NICKOLLS PETER
Published: July 2006

With the continuing development of new pacing and shock modalities, impJantabie cardioverter defibrillators must be able to recognize an increasingly wider range of arrhythmias so that therapy is delivered in an optimal way. Current rate‐based systems can no longer meet this need. It is, therefore, necessary to develop new techniques that consider waveform morphology in addition to heart rate. Any developments, however, must be compatible with the strict power and space constraints imposed by implantable devices. Artificial neurai networks offer a potentially viable way of meeting these objectives. In this article an artificial neural network based approach to the classification of arrhythmias from the ventricular intracardiac electrogram is described. It performs its classification on a set of easily extracted features that characterize waveform morphology and heart rate. Simulations showed that the artificial neural network performed better than a rate‐based scheme similar to those used in some commercial devices.
Ventricular Tachycardia Surgery in 1992: Did the Automatic Defibrillator Change This Approach?
Authors: TRAPPE HANS‐JOACHIM , KLEIN HELMUT , WENZLAFF PAUL , FRANK GUNTER , SICLARI FRANCESCO , GOTTE ANDREAS , LIGHTLEN PAUL R.
Published: July 2006

The role of ventricular tachycardia (VT) surgery has been changed since the automatic implantable cardioverter defibrillator (ICD) is available. We studied the follow‐up of 131 patients who underwent mapping guided surgery due to recurrent VT refractory to antiarrhythmic drug treatment. There were 65 patients operated upon between 1980–1985 (group I) and 66 patients between 1986–1991 (group II). Ten patients (8%) died perioperatively (< 3 weeks after surgery) [7/65 patients, 11%, in group I and 3/66 patients, 5%, in group II (P = 0.15)]. During a mean follow‐up of 41 ± 24 months, 38 of 121 patients died (31%), significantly more patients in group I (24/58 patients, 41%) than in group II (14/63 patients, 22%) (P < 0.05). In group I, there was a higher incidence of sudden (7/58 patients, 12%) or cardiac death (15/58 patients, 26%) than in group II (sudden death 4/63 patients, 6%, cardiac death 7/63 patients, 11%) (P < 0.05). There was a similar incidence of VT recurrences between group I(9/65 patients, 14%) and group II (9/66 patients, 14%). Our data show that the indication for VT surgery has changed since the ICD is available because of better patient selection.
Dressler's Syndrome Complicating Radiofrequency Ablation of an Accessory Atrioventricular Pathway
Authors: ROVANG KAREN S. , HEE TOM T. , PAGANO TOM V. , MOHIUDDIN SYED
Published: July 2006

Radiofrequency energy is being used frequently in catheter ablation of accessory pathways. This case reports a patient who underwent radiofrequency ablation that was complicated by the development of Dressler's syndrome.
ICD Implantation via Thoracoscopy without the Need for Sternotomy or Thoracotomy
Authors: FRUMIN HOWARD , GOODMAN GARY R. , PLEATMAN MARK
Published: July 2006

After development of the technique in mongrel dogs, implantable cardioverter defibrillator (ICD) patch and sensing lead implanlation was attempted via thoracoscopy, without sternotomy or thoracotomy, in three patients. Two large titanium mesh defibrillator patches and two “screw‐in” epicardial sensing leads were applied without difficulty in each of two patients. In a third patient, satisfactory placement of the defibrillator patches could not be achieved via thoracoscopy, necessitating thoracotomy. Defibrillation threshold (DFT), cardioversion energy requirement (CER), and rate and morphology signals in those patients with successful thoracoscopic implantation were comparable to those achieved by open technique. We conclude that ICD patch and sensing lead implantation via thoracoscopy is feasible.
Changes of the RR Interval and the QRS Morphology in AV Nodal Tachycardia: Further Evidence for Extranodal Involvement
Authors: VERTONGEN PATRICK , DETOLLENAERE MARC , JORDAENS LUC
Published: July 2006

A young patient wilh AV nodal tachycardia was referred for ablation. During electrophysiological testing, a stable succession of up to four different RR intervals with comcomitantly changing QRS morphologies were recorded. This observation might reflect the conduction of the reentry circuit through different extranodal “pathways” in the low right atrium. Radiofrequency current was applied near the ostium of the coronary sinus; this abolished conduction through the slow pathway, as dual AV conduction was no longer present. She remains free of recurrences for a follow‐up period of 8 months.
Comparison Between Patients with and without Reliahle Ventricular Escape Rhythm in the Presence of Long Standing Complete Atrioventricular Block
Authors: ROSENHECK SHIMON , BONDY CHAVA , WEISS AVRAHAM T. , GOTSMAN MERVYN S.
Published: July 2006

The underlying heart rhythm was evaluated in 74 patients with complete atrioventricular block and had a permanent pacemaker implantation. The pacing was inhibited for 10 seconds or until the patient developed symptoms of presyncope or syncope. Fifty‐six patients (74%) had a reliable escape with a mean cycle length of 2010 ± 596 msec and a mean escape interval of 2335 ± 971 msec. In 93% of these piatients the escape interval was < 4 seconds. The patients without reliable escape (24%), developed symptoms only after a mean of 7153 ± 1875 msec. The duration of the conduction disorder was longer in the patients without escape and the intraventricular conduction was slower. More patients without escape were treated with antiarrhythmic agents. Forty‐eight patients were followed for 1 year and underwent at least two different studies and 13% had different results at different tests. In conclusion, patients without reliable escape have a longer history of conduction disorder, a slower intraventricular conduction, and are frequently treated with antiarrhythmic agents. Even patients with reliable escape occasionally may show a greater pacemaker dependence; therefore, they should also be considered as pacemaker dependent.
Extended Protocol for Demonstration of Dual AV Nodal Physiology
Authors: BROOKS RODNEY , GOLDBERGER JEFFREY , KADISH ALAN
Published: July 2006

The incidence of dual atrioventricular (AV) nodal physiology was evaluated in 22 patients (14 males, 8 females, age 52 ± 18 years) undergoing electrophysiology studies for evaluation of ventricular tachycardia/honsustained ventricular tachycardia (n = 11), supraventricular tachycardia (n = 5), and syncope (n = 6). Patients with AV node reentrant tachycardia were excluded. Thirteen patients had riormal left ventricular function and nine patients (seven with coronary artery disease, two with dilated cardiomyopathy) had depressed left ventricular function. Single atrial extrastimuli (A2) were introduced after eight‐beat drives at paced cycle lengths of 550 msec and 400 or 450 msec beginning at coupling intervals of 650 and 500 or 550 msec, respectively. The coupling interval was decreased at 10‐msec intervals until AV node or atrial refractoriness. A second atrial extrastimulus (A3) was then added. A2 was fixed at 50 msec greater than the atrial or AV nodal refractory period. A3 was coupled to A2 at 650 and 500 or 550 msec and decremented as with single extrastimulation. Dual AV nodal physiology was defined by a 50‐msec increase in A2H2 or A3H3 with a 10‐msec decrement in the coupling interval or a discontinuous H1H2 versus A1A2 or H2H3 versus A2A3 curve. Using a single extrastimulus, 1 of 22 patients demonstrated dual AV nodal physiology. Using double extrastimuli, an additional four patients with dual AV nodal physiology were identified. The occurrence of dual AV nodal physiology determined using double extrastimuli is increased compared to using only a single extrastimulus (P = 0.03). In conclusion, dual AV nodal physiology can be demonstrated with greater frequency using an extended rather than a standard protocol.
Intracardiac Emergency Defibrillation for Refractory Ventricular Fibrillation During Implantation of Cardioverter Defibrillators with Nonthoracotomy Lead Systems
Authors: PITSCHNER HEINZ F. , NEUZNER JORG
Published: July 2006

Implantable cardioverter defibrillators (ICDs) are being implanted in increasing numbers. At inlraoperative defibrillation threshold tests refractory ventricular fibrillation (VF) requiring emergency open chest resuscitation is a major concern during impiantation of nonthoracotomy ICD lead systems. A new method of high energy endocardial/extrathoracic defibrillotion via the implanted ICD transvenous defibrillation electrode (TDE) was used to terminate refractory VF. During implantation of ICD with TDE in 20 patients refractory VF occurred in two patients. The arrhythmia was terminated with endocardial/extrathoracic defibrillation in both cases, and no complications were observed.
Effects of Verapamil on Electrophysiological Properties in Paroxysmal Atrial Fibrillation
Authors: KUMAGAI KOICHIRO , MATSUO KUNIHIRO , ONO MIYUKI , YAMANOUCHI YOSHIO , MOROE KAZUO , HAMASAKI NAOTAKA , ARAKAWA KIKUO
Published: July 2006

Verapamil is used to control ventricular response during atrial fibrillation (AF). Limited data is available on the effects of verapamil on atrial vuinerability in human AF. The effects of intravenous verapamil (0.15 mg/kg) on electrophysiological properties of the atrium were investigated in 12 patients with documented paroxysmal AF by electrophysiological studies. Sinus cycle length, sinus node recovery time, and the effective refractory period of the right atrium were not significantly affected by verapamil. The intraatrial conduction delay zone was significantly increased (33 ± 20 msec before verapamil versus 50 ± 22 msec after verapamil, P < 0.01, and the maximal intraatrial conduction delay was also significantly prolonged by verapamil, both to the His bundle region (30 ±12 msec before verapamil versus 42 ± 15 msec after verapamil. P < 0.01) and to the coronary sinus (40 ± 15 msec before verapamil versus 53 ± 17 msec after verapamil, P < 0.01). The fragmented atrial activity zone was significantly increased (15 ± 14 msec before verapamil versus 25 ± 22 msec after verapamil, P < 0.02), and the percentile fragmented atrial activity was also significantiy increased by verapami] (149 ± 18 msec before verapamil versus 174 ± 44 msec after verapamil, P < 0.05). The repetitive atriaJ firing zone remained unchanged. Sustained AF spontaneousiy occurred in only one patient after the administration of verapamil. Thus, verapamil may modulate the abnormal atrial electrophysiology in paroxysmal AF, and wouid favor production of atrial reentry.
Radiofrequency Catheter Ablation of Idiopathic Recurrent Ventricular Tachycardia with Right Bundle Branch Block, Left Axis Morphology
Authors: PAGE RICHARD L. , SHENASA HOSSEIN , EVANS JOSEPH J. , SORRENTINO ROBERT A. , WHARTON J. MARCUS , PRYSTOWSKY ERIC N.
Published: July 2006

Idiopathic ventricular tachycardia with right bundle branch block and left axis deviation morphology is a well described clinical syndrome. Previous sludies have mapped the tachycordia focus to the inferior septal region at the base of the posterior papillary muscle of the left ventricle. We describe two typical cases in a 20‐year' old man and 29‐year‐old woman in which the tachycardia focus was localized with endocardial mapping techniques. In both cases the ventricular tachycardia focus was ablated with application of radiofrequency current at the inferior septal region. There were no complications of the procedures. The patients remain asymptomatic over follow‐up of 7 and 4 months, respectively.
Ventricular Defibrillation in Canines with Chronic Infarction, and Effects of Lidocaine and Procainamide
Authors: WARE DAVID L. , ATKINSON JAMES B. , BROOKS MICHAEL J. , ECHT DEBRA S.
Published: July 2006

Prior studies in dogs with normal hearts have demonstrated that lidocaine increases but procainamide does not change the energy required for successful defibrillation. Because many postinfarct patients receiving implantable cardioverter defibrillator devices require adjunctive antiarrhythmic therapy, we have studied the effects of lidocaine and procainamide on the relationship between delivered voltage and defibrillation success in mongrel dogs 21 ± 3 days following ligation of the left anterior descending and first diagonal coronary arteries. Internal defibrillation testing using a patch‐patch electrode configuration was performed before and during the administration of saline controls (n = 10), lidocaine (n = 10) and procainamide (n = 10). The mean infarct size as determined by staining with tetrazolium was 13.4%± 8.3% of right and left ventricles, and did not differ significantly between groups. The 50% effective defibrillation (ED50) voltage increased with infusions of saline (16%± 15%), lidocaine (40%± 22%), and procainamide (13%± 15%) and the ED50 energy increased 41%± 44%, 104%± 62%, ond 35%± 36%, respectively. However, the increase in ED50 voltages and energies were significantly greater in animals receiving lidocaine compared to those receiving either saline control or procainamide (P < 0.01). There were trends toward change of hemodynamic parameters in all animals following baseline defibrllation testing, stroke volume declined 21%± 16%, and mean pulmonary artery and aortic pressure increased by 22%± 25% and 11%± 15%, respectively. In conclusion, unlike our previous studies in dogs with normal hearts, in this model hemodynamic deterioration occurred with repeated fibrillation and defibrillation, and defibrillotion voltage requirements increased in the control series. Taking into consideration the increase in defibrillation voltage requirements over the duration of the experiments, lidocaine increases and procainamide does not change ED50; thus, their effects are similar in normal and infarcted canine hearts.
Interaction Between Accessory Pathways Resulting in Inability to Induce Reciprocating Tachycardia
Authors: FLECK R. PETER , GHEN PENG‐SHENG , BOYGE KER , HENJUM STANLEY , BRENNAN EDMUND , FELD GREGORY K.
Published: July 2006

A 44‐year old male with Wolff‐Parkinson‐White syndrome presented with atrial fibrillation. The patient was found at the electrophysioiogical study to have two accessory pathways, one concealed and the other conducting exclusively in the anterograde direction. After radiofrequency catheter ablation of the anterograde conducting pathway, orthodromic reciprocating tachycardia, which previously could not be induced despite an aggressive protocol, was easily induced. Ablation of the concealed pathway resulted in termination of the tachycardia and suppression of inducibility. We propose that interaction between the two accessory pathways resulted in an inability to induce reciprocating tachycardia.
A Comparison of Ventricular Arrhythmias Induced with Programmed Stimulation Versus Alternating Current
Authors: CUA MARK , VELTRI ENRICO P.
Published: July 2006

In patients undergoing implantation and testing of the implantable cardio‐verter defibrillator (ICD), alternating current (AC) may be used to induce ventricular tachyarrhythmias in a prompt, safe, and efficient manner. These arrhythmias have been previously reported to be similar to those induced during programmed electrical stimulation (PES). We compared the ventricular tachyarrhythmias induced by both methods in 14 patients: 8 male, 6 female; mean age 61 years; coronary disease in 10, cardiomyopathy in 4; mean ejection fraction 31%. The presenting arrhythmia was nonsustained ventricuiar tachycardia (VT) in four, sustained monomorphic ventricular tachycardia (SMVT) in five, ventricular fibrillation (VF) in four, and unknown in one patient with syncope. PES (single, double, triple extrastimuli; burst pacing) and AC (1–2 sec application) stimulation via right ventricular endocardial electrode catheter was performed off antiarrhythmic drugs in the nonsedated state. PES induced SMVT in nine, polymorphic VT in two, and VF in three. AC induced VF in all patients. Although AC can reliably induce ventricular tachyarrhythmias during de/ibrillation threshold and ICD testing, there is poor correlation to PES induced tachyarrhythmias.
Sensitivity and Specificity of the Tilt Table Test in Young Patients with Unexplained Syncope
Authors: FOUAD FETNAT M. , SITTHISOOK SURAPUN , VANERIO GABRIEL , MALONEY JAMES , OKABE MASANORI , JAEGER FRED , SCHLUCHTER MARK , MALONEY JAMES D.
Published: July 2006

The usefulness of the head‐up tilt testing (HUT) has heen previously addressed in diagnosing vasovagal neuroregulatory syncope in the teenage population. However, data concerning sensitivity and specificity is deficient due to the lack of control groups. We compared the response to HUT in young patients referred because of syncope or near syncope (n = 44, mean age 16 ± 3 years SD) to healthy young volunteers with a normal physical examination and no previous history of syncope (n = 18, mean age 16 ± 2 years) and io determine the sensitivity and specificity of HUT. The graded tilt protocol was performed at 15°, 30°, and 45° (each for 2 min), and then 60° for 20 minutes. Cuff blood pressure was measured every minute and lead IIECG was continuously monitored. Results; 25 of the 44 patients (57%) developed a vasovagaJ response or became symptomatic after 13.8 ± 5.7 minutes of HUT. Three of the 18 volunteers (17%) had a vasovagal response and became symptomatic after 9 ± 3 minutes of HUT. There was no statistical difference among the four groups (with and without tilt induced vasovagal response) in terms of age and baseline hemodynamic data. The sensitivity of 20 minutes HUT was 57% and its specificity was 83%. The presyncopal hemodynamic response in patients with history of syncope that was characterized by a significant decrease in systolic blood pressure and lack of increase of diastolic blood pressure as compared with baseline and with other groups. Gonclusions: 20 minutes at 60° HUT has a high specificity for the diagnosis of vasovagal syncope. Its limited sensitivity is counterbalanced by the advantage of limiting the incidence of false‐positive results in patients without the vasovagal syndrome.
Catheterization Technique for Laser Photoahlation of Atrioventricular Conduction from the Aortic Root in Dogs
Authors: LITTMANN LASZLO , SVENSON ROBERT H. , CHUANG CHI HUI , KEMPLER PAL , SPLINTER ROBERT , And JAN R. TUNTELDER. , TATSIS GEORGE P.
Published: July 2006

A simple catheterization technique for producing suppression or block of atrioventricular (AV) conduction in dogs by neodymium:YAG (Nd:YAG) laser photocoagulationfrom the aortic root is described. In 14 canines, electrode catheters were percutaneously advanced to the high right atrium, to the His bundle area at the tricuspid valve (right His (RHJ), and the noncoronary cusp of the aortic valve (left His [LH]). A 400μ optical fiber was fed into the lumen of the LH catheter. Continuous wave Nd:YAG lasing at λ= 1,064 nm at 15–20 watts was performed at the site of the largest recorded LH deflection, opposite ta the RH catheter, until complete AV block (CAVB, group I, eight dogs) or persistent A‐H prolongation (AHPr, group 11, four dogs) occurred; in two animaJs, laser photoablation was unsuccessful. CAVB and AHPr were achieved in < 140 seconds of lasing. Mean lasing time was 51 ± 41 seconds, total energy delivered, 776 ± 601 J. There were no complications. Dogs were followed for up to 120 days. In group I, 6/6 dogs followed /or at least I week continued to have CAVB (three AV nodal, five infra‐His). In group II, 1/4 dog progressed to infra‐His CAVB; 3/4 had depressed AV nodal function. AV block was not reversed by isoproterenol. Aortic root angiograms revealed intact valve function in all. Histology showed various degrees of damage and repair of AV functional tissue. There were no valvular perforations. Transcatheter Nd:YAG laser photocoagulation of the AV junction from the aortic root is a fast, simple, and safe method for creating AV conduction block in dogs.
Inappropriate Implantable Cardioverter Defibrillator Shocks Secondary to Sensing Lead Failure: Utility of Stored Electrograms
Authors: ALMEIDA HILARY F. , BUCKINGHAM THOMAS A.
Published: July 2006

The Ventritex Cadence is a fourth generation implanta‐ble cardioverter defibrillator that provides for retrieval of stored eiectrograms related to therapy. In two patients, this feature enabled us to troubleshoot sensing lead problems, in one instance be/ore it became clinically apparent. This may be an important consideration in selecting an appropriate device.
Long‐Term Performance of Epimyocardial Pacing Leads in Adults: Comparison with Endocardial Leads
Authors: HELGUERA MARCELO E. , MALONEY JAMES D. , WOSCOBOINIK JAVIER R. , TROHMAN RICHARD G. , MCCARTHY PATRICK M. , MORANT VICTOR A. , WILKOFF BRUCE L. , CASTLE LON W. , PINSKI SERGIO L.
Published: July 2006

The long‐term performance of epimyocardiaJ pacing leads in children is well established, but few studies have analyzed the performance in adults. This issue has clinical relevance in view of the increased use of epimyocardial leads with implantable cardioverter defibrillator and antitachycardia pacing systems. We analyzed 93 epimyocardial pacing “systems” (121 leads: 65 unipolar, 28 bipolar) in adult patients (age 57 ± 16 years), implanted since January 1980. Two different models were studied: Medtronic 4951 “Stab–on” (n = 35) and Medtronic 6917/6917A “Screw‐in” (n = 58). A control group was created by randomly matching each epimyocardial system with two endocardial leads, according to age and year of implant. Epimyocardial and endocardial leads were followed‐up for 44 ± 35 and 43 ± 35 months, respectively (P = NS). Freedom from failure for epimyocardial leads was 0.91 (95% Confidence Interval [95% CI] = 0.82 to 0.96) at 5 years, and 0.91 f95% CI = 0.69 to 0.98) at 10 years. No difference was found between the two analyzed models. Freedom from failure for endocardial leads was 0.97 (95% CI = 0.93 to 0.99) and 0.90 (95% CI = 0.61 to 0.97) at 5 and 10 years, respectively. Epimyocardial Jeads had a significantly poorer short‐term survival than endocardiaJ leads, secondarily to earlier “technique related” failures (P = 0.03; relative riskc 3.0; Wilcoxon test). However, overall long‐term performance was similar to endocardial leads. Epimyocardial pacing leads, meticulously implanted and tested, have a long‐term performance similar to endocardial pacing leads.
Anatomical and Morphological Evaluation of Pacemaker Lead Compression
Authors: JACOBS DONALD M. , FINK ANDREW S. , MILLER ROBERT P. , ANDERSON W. ROBERT , MCVENES RICK D. , LESSAR JOSEPH F. , COBIAN KENNETH E. , STAFFANSON DALE B. , UPTON JAMES E. , BUBRICK MELVIN P.
Published: July 2006

In recent years, pacemaker lead failure due to compressive damage has been reported with increasing frequency. To document the mechanism of this failure, we evaluated explanted mechanically damaged leads with electrical testing, optical microscopy, and in some cases, scanning electron microscopy (SEM) In addition, we performed an autopsy study to measure the compressive loads on catheters placed percutaneously through the costoclavicular angle, as well as by cephalic cutdown. Of the 49 explanted compression damaged leads with enough clinical data for analysis, all had been placed by percutaneous subclavian puncture. Our autopsy data confirmed the significant increase in pressures generated in the costoclavicular angle for medial percutaneous subclavian catheterization (126 ± 26 mmHg) compared to a more lateral percutaneous subclavian puncture (63 ± 15 mmHg) or a cephalic cutdown (38 ± 13 mmHg) (P < 0.01). In vivo coil compression testing documented loads up to 100 pounds per linear inch of coil and a compressive morphology by SEM identical to that seen in the clinical explants. Pacemaker leads appear to be susceptible to compression damage when placed by subclavian venipuncture. When possible, leads should be placed such that they avoid the tight costoclavicular angle.
Usefulness of Fluoxetine Hydrochloride for Prevention of Resistant Upright Tilt Induced Syncope
Authors: GRUBB BLAIR P. , WOLFE DOUGLAS A. , SAMOIL DANIELA , TEMESY‐ARMOS PETER , HAHN HARRY , ELLIOTT LAURA
Published: July 2006

Recurrent vasovagally mediated episodes of hypotension and bradycardia are a common cause of recurrent syncope that can be identified by head‐upright tilt table testing. Although the use of beta blockers, transdermal scopolamine, disopyramide, and fludrocortisone may be helpful in preventing further episodes, some patients are intolerant of or respond poorly to each of these agents. Following anecdotal observations, we investigated the utility of fluoxetine (a serotonin re‐uptake antagonist) in preventing head‐upright tilt induced hypotension/bradycardia in patients unresponsive to or intolerant of standard therapy. Sixteen patients (7 men and 9 women, mean age 42 ± 21 years) with recurrent syncope and positive head‐upright tilt studies (refractory to normal therapy) were placed on fluoxetine and restudied 5–6 weeks afterward. Three patients were intolerant of the medication. Of the 13 patients who underwent repeat tilt studies, seven patients (53% of the patients retested or 44% of the total group) were rendered tilt table negative, and, over a mean follow‐up period of 19 ± 9 months, have remained asymptomatic. We conclude that fluoxetine may be an effective therapy in patients with recurrent vasovagally mediated syncope refractory to other forms of therapy.