bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in the Amplitude of Endocardial Electrograms Following Defibrillator Discharge: Comparison of Two Lead Systems
Authors: JUNG WERNER , MANZ MATTHIAS , MOOSDORF RAINER , TEBBENJOHANNS JüRGEN , PFEIFFER DIETRICH , LüDERITZ BERNDT
Published: July 2006

Changes in the amplitude of endocardial electrograms after an unsuccessful shock attempt have been demonstrated to cause failure of redetection of ventricular fibrillation in patients using an integrated sense‐pace defibrillating lead system. Thus, the objective of this study was to compare the effects of defibrillator shocks on the amplitude of endocardial electrograms in 26 patients using two different nonthoracotomy systems, a previous lead (model 0062) or a redesigned version (model 0072). At implant, bipolar endocardial electrograms were obtained before each shock application, during initial detection and redetection of ventricular fibrillation in case the applied shock was unsuccessful, and during intervals of 5, 10, 20, 30, 60, and 120 seconds after each shock delivery. No significant difference was noted in endocardial amplitudes between the lead models 0062 and 0072 during baseline sinus rhythm (12.2 ± 4.6mV vs 11.4 ± 3.8 mV), and during initial ventricular fibrillation (7.0 ± 2.4 mV vs 7.6 ± 2.3 mV). During redetection of ventricular fibrillation, however, there was a significant difference (P = 0.0006) in endocardial amplitudes (3.4 ± 1.9 mV vs 6.6 ± 2.3 mV) between both leads tested. Comparing lead models 0062 and 0072, marked differences were found in endocardial amplitudes during sinus rhythm 5, 10, and 20 seconds after successful arrhythmia termination: 2.8 ± 1.9 mV vs 8.6 ± 2.9 mV (P < 0.0001), 4.6 ± 2.9 mV vs 9.2 ± 3.2 mV (P = 0.0007), and 6.4 ± 4.0 mV vs 10.5 ± 3.6 mV (P = 0.01). At predischarge testing, failure of redetection of ventricular fibrillation was documented in two patients with the lead model 0062 requiring external defibrillation to restore sinus rhythm. These findings demonstrate a significant less postshock attenuation of the endocardial electrogram amplitudes during persistent ventricular fibrillation after an unsuccessful shock attempt as well as during sinus rhythm immediately following an effective shock delivery using the redesigned lead system model 0072 compared to the electrogram amplitudes obtained in patients using the previous lead model 0062.
Electrode Polarity Does Not Alter the Initial Ventricular Activation Sequence During Pacing with Extracardiac Electrodes
Authors: BIRKUI PIERRE J. , SAVARD PIERRE , HELIE FRANQOIS , CARDINAL RENé
Published: July 2006

Ventricular epicardial mapping was performed in six closed‐chest anesthetized dogs to investigate the cardiac electrical response to external pacing. A right thoracotomy was performed, complete A V block was produced by formaldehyde injected into the AV node and a sock electrode array, comprised of 127 unipolar electrodes, was placed over the ventricles. Isopotential and isochronal epicardial maps were generated by computer from the unipolar electrograms. Unipolar stimulation pulses were applied between pairs of different types of cutaneous (metal, carbon) and esophageal (metal) electrodes, and recordings were performed at maximum lung inflation. Isopotential maps recorded during the stimulation artifacts showed that the epicardial electrical field was little affected by the type of electrode but depended mostly on electrode position. A reproducible and relatively uniform apex‐to‐base potential gradient was regularly produced with anteroposterior and anteroesophageal electrode configurations. This uniform potential gradient induced ventricular activation sequences that showed interindividual differences. Thus, for each dog, the areas of initial activation observed on the isochronal maps during pacing tended to remain the same (i.e., apical, lateral, and anterior) despite changes in the stimulation protocol. Inverting the polarity of the electrodes did not appreciably change the site of origin of activation (81 % remained the same) and activation never originated from the area showing the most negative potential during the stimulation artifact. In conclusion, since electrode polarity does not seem to alter the ventricular activation sequence during cardiac pacing with extracardiac electrodes, the standard nomenclature for cutaneous patches, which defines the negative electrode as the “active” electrode, may have to be revised.
ECG Criteria to Distinguish Between Aberrantly Conducted Supraventricular Tachycardia and Ventricular Tachycardia:Practical Aspects for the Immediate Care Setting
Authors: DREW BARBARA J. , SCHEINMAN MELVIN M.
Published: July 2006

To reevaluate ECG criteria for distinguishing Supraventricular tachycardia (SVT) with aberrant conduction from ventricular tachycardia (VT), 133 wide QRS tachycardias were recorded in patients undergoing invasive electrophysiological (EP) study. Surface ECG leads (standard 12‐lead and MCL leads) were compared to EP recordings to provide a standard for correct diagnosis. Criteria from six studies were pooled to select QRS morphology agreed to be highly specific for SVT or VT (specificity > 90%). Some morphological criteria were modified to simplify analysis for the immediate care setting. Results: Although the 12‐lead ECG was useful in distinguishing aberrancy from VT, 13 tachycardias (10%) were misdiagnosed or could not be diagnosed. The MCL1 lead recorded clearly different QRS morphology than lead V1 in 40% of VT cases and was diagnostically inferior to V1.Most established criteria were highly specific for a diagnosis, but not very sensitive as individual criteria. Neither a QRS width of > 0.14 seconds nor a monophasic R wave pattern in lead V1 were valuable in diagnosing VT. Conclusions: In distinguishing SVT with aberrant conduction from VT: (1) Although the 12‐lead ECG is valuable, about 1 in 10 wide QRS tachycardias defy differentiation; (2) tachycardias > 190 beats/mm often do not exhibit unequivocal criteria with which to make a certain diagnosis; (3) multiple leads are required for accurate assessment of QRS width, presence of AV dissociation or VA block, QRS axis, and morphological criteria; and (4) the MCL1 lead cannot be substituted for V1 in the use of morphological criteria for VT.
Pseudo Fracture of a Defibrillating Lead
Authors: KRATZ JOHN M. , SCHABEL STEPHEN , LEMAN ROBERT M.
Published: July 2006

Routine follow‐up chest X my of several patients with the Endotak™ transvenous pacing lead suggested fracture of the conductor at the distal end of the proximal defibrillating coil. Electrical evaluation of these patients' leads demonstrated them to be working normally. Multiple x‐ray views of a new undamaged lead demonstrated that in some projections the Endotak lead may appear fractured in spite of normal continuity of the conductors. Physicians dealing with these patients should be aware of this confusing x‐ray finding.
Peritoneal Migration of an Abdominally Implanted Epicardial Pacemaker: A Cause of Intestinal Obstruction
Authors: GOMEZ CARLEN , DICK MACDONALD , HERNANDEZ RAMIRO , GORAN ARNOLD G. , CROWLEY DENNIS , SERWER GERALD A.
Published: July 2006

We report the case of a 10‐year‐old child with an abdominally implanted epicardial pacemaker that eroded through the peritoneum and migrated to an intraperitoneal location, resulting in partial and then complete intestinal obstruction. This potentially life‐threatening complication should be considered when a patient with an abdominally implanted pacemaker presents with abdominal pain.
Efficacy of Different Treatment Strategies for Neurocardiogenic Syncope
Authors: NATALE ANDREA , SRA JASBIR , DHALA ANWER , WASE ABDUL , JAZAYERI MOHAMMAD , DESHPANDE SANJAY , BLANCK ZALMEN , AKHTAR MASOOD
Published: July 2006

Objectives: The purpose of this study was to evaluate the efficacy of different therapeutic approaches for patients with a history of syncope and positive head‐up tilt testing. Background: Head‐up tilt testing has gained broad acceptance as a reliable diagnostic method for the assessment of patients with recurrent unexplained syncope. However, once the diagnosis is established, there is no consensus on the most appropriate treatment. In this respect, efficacy of drug therapy in preventing recurrence of symptoms in such patients is not entirely clear, and controversies exist regarding the need to confirm the effects of pharmacological interventions. Methods: Clinical follow‐up was obtained in 303 patients with a history of syncope and positive head‐up tilt testing. After the diagnostic head‐up tilt, patients were assigned to different therapeutic approaches according to their preference or logistic impediments. Of 303 patients, 44 received empiric therapy, 210 were treated with medications proven effective during repeated head‐up tilt testing, and 49 refused or discontinued medical therapy. The three groups were similar with regard to age, sex, and clinical presentation. The mean follow‐up was 2.8 ±1.8 years. Among the patients treated according to head‐up tilt guided therapy, 130 were on beta blockers, 35 on theophylline, 10 on ephedrine, 31 on disopyramide, and 4 on miscellaneous regimens. Empiric treatment consisted of beta blockers in 37 of 44 patients and other drugs in the remaining patients. Results: During the follow‐up, recurrence of symptoms was experienced in 12 (6%) of the 210 patients receiving the head‐up tilt guided therapy, 16 (36%) of 44 in the empiric therapy group, and 33 (67%) of 49 in the no therapy group. Recurrence of symptoms in patients on empiric or no therapy was significantly more frequent as compared to the head‐up tilt guided therapy group (P<0.01). Conclusions: In patients with unexplained syncope and positive upright tilt testing, therapeutic strategies identified on the basis of response during head‐up tilt have a more positive impact on the recurrence of symptoms during follow‐up.
Echocardiographic Assessment of Epicardial Defibrillator Patch Electrodes
Authors: EICHELBERGER JAMES P. , GAGE LAWRENCE E.
Published: July 2006

We performed a blinded controlled analysis of transthoracic echocardiograms on IK patients before and after epicardial defibrillator patch electrode placement to determine the accuracy of echocardiography in identifying defibrillator patches and to determine possible echocardiographic findings that may correlate with defibrillator function or perioperative complications. The sensitivity of two‐dimensional echocardiography in detecting defibrillator electrodes was 72% by one observer and 39% by a second observer. Corresponding specificities were 67% and 83%, respectively. The discordance rate was 27%. The echocardiographic finding of patch buckling was not observed, and echocardiographic estimates of the distance from patch to epicardium did not correlate with defibrillator threshold at the time of surgery. We conclude that: echocardiography is only moderately sensitive and specific in identifying epicardial defibrillator electrodes; significant interobserver variability does exist; and echocardiography therefore cannot be used reliably to assess for pericardia] changes or possible complications of patch electrode placement.
Modulation of the Arterial Coronary Blood Flow by Asynchronous Activation with Ventricular Pacing
Authors: AMITZUR GIORA , MANOR DAN , PRESSMAN ASHER , ADAM DAN , HAMMERMAN HAIM , SHOFTI RONA , BEYAR RAFAEL , SIDEMAN SAMUEL
Published: July 2006

This study aims to test the assumptions that: (1) coronary arterial flow is attenuated in an early activated region by ventricular pacing; (2) asynchronous mechanical activation caused by ventricular pacing under controlled perfusion pressure and intact coronary tone is associated with reduced coronary flow compared to atrial pacing; and (3) abolishment of vascular tone under controlled perfasion pressure diminishes the expected difference in blood flow between atrial and ventricular pacing. Blood flow velocity (BFV) in the left anterior descending (LAD) and the left circumflex arteries (CFX) and a wall thickening index were measured in 14 open‐chest dogs under normal conditions, and constant perfasion pressure. Four pacing sites were used: right atrium (RAJ, mid‐right ventricle (RVyJ, mid‐left ventricle (LVp), and left ventricular apex (Apex. Pacing modes were either sequential ventriculoatrial (VA) (protocol A, n = 7), or sequential atrioventricalar (AV) (protocol B, n = 7), with a shorter AV difference (30 msec) than normal. Residis: BFV was decreased in the LAD during HV and Apex, pacingby 9.7%‐12.9% versas LVp and by 1.6%‐14.6% versus LVp (P < 0.05). No BFV variations were observed in the CFX. Flow velocity conductance (FVC = mean blood flow velocity divided by the mean aortic pressure) was higher by 16%‐28% in the CFX for the three ventricular pacing sites versus the airial pacing, and higher by 14.1%± 6.1% only in LVp versus RAp pacing in the LAD (P < 0.05). Wall thickening index reduced during ventricular pacing in all three ventricular sites by 50%‐64% (P < 0.05) compared to atrial pacing. Under constant perfusion pressure, LAD blood flow decreased with ventricular pacing as compared to right atrial pacing; this was particularly pronounced during the diastolic phase (16.6%−45.5%, P < 0.02). Normalized oscillatory flow amplitude (OFA.J was reduced in RVy, pacing compared to RAp and LVp pacing (16.2 ± 3.5 and 21.7%± 4.1%, respectively, P < 0.03). The variations in blood flow and OFAn disappeared with adenosine‐mediated maximum vasodilatation. Summary; (1) Mean and phasic flows are reduced in the early activated LAD region by ventricular pacing (RVp, Apex. (2) Under controlled perfusion pressure and intact vascular tone, ventricular pacing compromises blood flow compared with atrial pacing. (3) This effect disappears when vascular tone is eliminated by intracoronary injection of adenosine, suggesting that the coronary autoregulation is responsible for some of the effects.
Pacemaker Induced Superior Vena Cava Obstruction: Management by Spiral Vein Graft
Authors: ODELL J.A. , KEETON G.R. , MILLAR R.N. SCOTT , BENINGFIELD S.J.
Published: July 2006

A 35‐year‐old male developed superior vena cava (SVC) obstruction due to multiple retained pacemaker leads. This caused cyanosis and suffusion of the head and neck during arm exercise, with desaturation from 99%‐90% demonstrated by ear oximetry. The SVC was bypassed using a spiral vein graft because of worsening symptoms. Dramatic improvement resulted, with desaturation no longer demonstrable.
Atrial “J” Pacing Lead Retention Wire Fracture: Radiographic Assessment, Incidence of Fracture, and Clinical Management
Authors: LLOYD MARGARET A. , HAYES DAVID L. , HOLMES DAVID R.
Published: July 2006

In November 1994, Telectronics Pacing Systems issued a voluntary recall of their Accufix™330–801 and 329–701 “J”‐shaped atrial pacemaker leads. To assess the integrity of the lead, 156 consecutive patients with the Accufix™330–801 atrial lead implanted underwent fluoroscopic screening. Leads were visualized in at least two orthogonal views. When identified, fractured retention wires were classified into one of four groups, depending on the degree of wire extrusion outside of the lead insulation. Results; Of the 156 patients, 35 patients (22.4%) had a definite retention wire fracture, and an additional 13 patients (8.3%) had indeterminate leads. Neither the age of the patients, the time since lead implant, nor the site of fracture correlated with the incidence of wire fracture. When analyzed to include indeterminate leads that were re‐evaluated and found to be fractured, as well as two leads that were identified as being radiographically normal but found to be fractured after extraction, the incidence of retention wire fracture is 25.6% (40 of 156 leads evaluated). Conclusions: The incidence of retention wire fracture in the Accufix™ 330–801 lead is significantly higher than originally reported. Patients should be notified of the potential dangers associated with this lead. Cardiac digital fluoroscopy is an effective method of screening for wire fracture. Leads with fractured retention wires should be extracted and those with normal fluoroscopic appearance should undergo regular fluoroscopic screening.
New Observations on Decremental Atriofascicular and Nodofascicular Fibers: Implications for Catheter Ablation
Authors: OKISHIGE KAORU , FRIEDMAN PETER L.
Published: July 2006

Introduction: The purpose of this study was to characterize the anatomy and physiology of accessory pathways that exhibit anterograde decremental conduction. Results: Among 100 consecutive patients with an accessory pathway undergoing electrophysiological study, six individuals with decremental anterograde accessory pathway conduction were identified. Anterograde accessory pathway effective refractory periods and conduction curves were assessed by atrial extrastimulus testing. Atrial pace mapping and ventricular activation sequence mapping were used to define accessory pathway origin and insertion. Surgical ablation (N = 1) or radiofrequency catheter ablation (N = 3) was performed based on accessory pathway anatomy as determined during electrophysiological study. Four of 6 patients had gaps in anterograde accessory pathway conduction. Two patients had evidence of functional longitudinal dissociation in the accessory pathway. Five of 6 patients had atriofascicular fibers with an atrial rather than AV nodal site of origin of their decrementally conducting accessory pathway and with distal insertions in the right bundle branch. Among these five patients, a right posterior atrial origin was nearly as common as a right anterior atrial origin. One patient had a true nodofascicular fiber that arose from the AV node, inserting distally into the left bundle branch. Conclusion: Most accessory pathways with anterograde decremental conduction arise from the right anterior or right posterior atrium, not the AV node. A gap in anterograde accessory pathway conduction and functional longitudinal dissociation are common in such accessory pathways. Surgical or catheter ablation of such pathways is effective when directed at the atrial origin of the accessory pathway. True nodofascicular fibers arising from the AV node are rare. These may insert distally in the left ventricle. Catheter ablation of the proximal origin of such fibers is likely to result in complete AV block.
Benefits and Potential Risks of Atrial Antitachycardia Pacing After Repair of Congenital Heart Disease
Authors: RHODES LARRY A. , WALSH EDWARD P. , GAMBLE WALTER J. , TRIEDMAN JOHN K. , SAUL J. PHILIP
Published: July 2006

Atrial reentry tachycardia is common after surgical repair of congenital heart disease. The arrhythmia is often difficult to treat and is occasionally life‐threatening. This study reports experience with atrial antitachycardia (AAIT mode) pacing for the management of atrial reentry tachycardia, with emphasis on the risks and benefits of automatic pacing therapy. Eighteen patients (2–32 years of age) with a variety of congenital heart lesions underwent atrial antitachycardia pacemaker placement for recurrent atrial tachycardia that was amenable to pace termination prior to the implantation procedure. An appropriate antitachycardia program was determined by repeated induction and termination of atrial tachycardia using the noninvasive programmed stimulation mode of the pacemaker. Over 4–30 months of follow‐up, 6 patients had 189 episodes of tachycardia successfully converted with AAI‐T pacing, 4 patients had 8 episodes of tachycardia detected hut not successfully converted, and 8 patients had no episodes of tachycardia with antibradycardia pacing alone. The number of patients receiving pharmacological therapy other than digoxin or beta blockade fell from 12 to 6, Two subjects died suddenly, 1 while wearing a Holter monitor. In both, tachycardia was detected and pace cardioversion attempted. Conclusions: Atrial antitachyardia pacing is a useful tool in the management of patients with congenital heart disease and atrial arrhythmias; however, in selected cases, it may not prevent and may even exacerbate the lethal complications of the tachycardia. Antitachycardia function evaluation is recommended under varying levels of autonomic stress prior to institution of automatic therapy.
Doppler Guided Extrathoracic Introducer Insertion
Authors: FYKE F. EARL
Published: July 2006

Recent reports have raised concern over the use of standard subclavian puncture for placement of permanent pacing leads. This study reports the initial experience of one implanter in 59 consecutive, unselected patients undergoing implantation of a variety of pacing leads in whom a simple Doppler flow detector was used to guide extrathoracic venipuncture of the lateral subclavian/axillary vein. A total of 100 leads were placed for 48 right‐ and 11 left‐sided systems. Lead insertion by this technique was successful in all patients. One small pneumothorax and two uncomplicated arterial punctures occurred. One patient's leads were revised electively because of unacceptable loss of redundancy when standing. There have been no infections or other late complications. A simple Doppler flow detector appears to be useful in identifying the lateral subclavian/axillary vein for extrathoracic pacemaker lead placement.
Use of the Saline Infusion Electrode Catheter for Improved Energy Delivery and Increased Lesion Size in Radiofrequency Catheter Ablation
Authors: MITTLEMAN ROBERT S. , HUANG SHOEI K. STEPHEN , TAN De GUZMAN WILSON , CUÉNOUD HENRI , WAGSHAL ALAN B. , PIRES LUIS A.
Published: July 2006

Although radiofrequency catheter ablation has undergone explosive growth as the treatment for a variety of arrhythmias, a limiting factor with the existing catheter delivery system has been the relatively small size of the lesions, which appears to be in part due to coagulum formation around the catheter tip, producing a rise in impedance and limiting energy delivery. In order to test the hypothesis that infusion of saline during radiofrequency current application can increase the lesion size and decrease the incidence of impedance rise, ten dogs were each given two radiofrequency ablation lesions to the left ventricular endocardium. One of these lesions was delivered with a standard 7 French quadripolar catheter with a 2‐mm tip, and the second was done with a 7 French Iuminal electrode catheter (also with a 2‐mm tip) for the infusion of normal saline during the delivery of radiofrequency energy. Energy was delivered for 60 seconds at either 10 or 20 watts at two distinct sites in the left ventricle for each animal. Four to 7 days following ablation, the animals were sacrificed for pathological examination. The lesions created with the saline infusion catheter were significantly bigger than those produced with a standard catheter (7.3 × 7.0 × 5.1 vs 5.2 × 4.9 × 3.5 mm, respectively, P < 0.001). At the lower energy level (10 W), none of the animals with the saline infusion catheter experienced an impedance rise versus 3 of 5 of the animals in whom the standard catheter was used. At the higher level (20 W), only 1 of 5 dogs had an impedance rise with the saline infusion catheter versus 5 of 5 with the standard catheter. We conclude that the use of a saline infusion catheter for radiofrequency energy delivery during catheter ablation produces a significantly larger lesion than that produced with a standard catheter and is effective in preventing impedance rise.
Postpartum Syncope
Authors: GRUBB BLAIR P. , KOSINSKI DAN , SAMOIL DANIELA , POTHOULAKIS ANTHONY , LORTON MICHAEL , KIP KATRINKA
Published: July 2006

Recurrent unexpected syncope may have severe consequences and result in serious injury. This is especially the case in the immediate postpartum period when maternal syncope may have a disastrous effect on the infant as well as the mother. We report on 12 women who developed episodic hypotension resulting in syncope in the immediate postpartum period and describe the distinguishing characteristics of their presentation, tilt table results, and responses to therapy. Postpartum syncope represents a unique subgroup of syncopal patients who need to be recognized and treated in order to prevent potentially serious injury to both mother and infant.
Accuracy and Clinical Utility of Transtelephonic Pacemaker Follow‐Up
Authors: GESSMAN LAWRENCE J. , VIELBIG ROGER E. , WASPE LAWRENCE E. , MOSS LEONARD , DAMM DONNA , SUNDEEN FAYE
Published: July 2006

The diagnostic accuracy of transtelephonic pacemaker monitoring (TTM) has been quantified in a retrospective study involving 369 patients in three U.S. cardiac centers. Using existing medical records, TTM findings in a total of 413 reports were judged for equivalence to the findings of subsequent physical examinations in pacemaker clinics. This study found TTM follow‐up testing to have a sensitivity of 94.6%, specificity of 98.5%, positive predictive value of 93.3%, and negative predictive value of 98.8%. The study also documents the clinical utility of TTM in identifying various modes of pacemaker malfunctions and instances of significant arrhythmia.
Pacemaker Function During Radiofrequency Ablation
Authors: PFEIFFER DIETRICH , TEBBENJOHANNS JÜRGEN , SCHUMACHER BURGHARD , JUNG WERNER , LÜDERITZ BERNDT
Published: July 2006

There are increasing numbers of radiofrequency current ablation procedures being reported. Selected patients have antitachycardia or antibradycardia pacemakers. The pacemaker behavior during and after ablation procedures differs widely. We report on the pacemaker reaction of 25 patients with 13 different devices, most with unipolar electrodes. Sensing failures were observed in 8 (32.0%) and pacing failures in 4 (16.0%) patients. Prolonged pauses and induction of tachyarrhythmias were observed. No pacemaker damage was seen although it is reported by other investigators. We recommend deactivation of implanted generators and an external bipolar pacing electrode. Manufacturers should focus their attention on this problem and protect the generators and their functions for 500 kHz radiofrequency current.
Sinus Node Reentrant Tachycardia
Authors: GOMES J. ANTHONY , MEHTA DAVENDRA , LANGAN M. NOELLE
Published: July 2006

This review article discusses the electrophysiological basis of sinus node reentry, clinical features of sinus node reentry, and the management of this uncommon tachycardia with drugs and ablative therapy. It also proposes the use of the term “sinoatrial reentrant tachycardia” for this form of tachycardia.
Spontaneous Twisting of an Implanted Pacemaker Electrode in Three Cases
Authors: GIALAFOS JOHN , SIAMAS GEORGE , KANDILAS JOHN , GATZOULIS KOSTAS , TOUTOUZAS PAVLOS
Published: July 2006

We present three cases of an unusual pacing lead aberration occurring at different times after implantation. In the first patient, the electrode was twisted close to the pacemaker, and dislodgment occurred on the 40th postoperative day. In the second case, there was only proximal twisting of the electrode. In the third case the electrode was twisted in two places: proximal to the pacemaker, and distal, within the right atrium. The complication was managed successfully by reimplanting the same electrode after stiffening the lead near the generator with a portion of the stylet.
Initial Clinical Experience with a New Dual Sensor SSIR Pacemaker Controlled by Body Activity and Minute Ventilation
Authors: ALT ECKHARD , COMBS WILLIAM , FOTUHI PARWIS , BAMBL ERWIN , WAHLSTRAND JOHN , WILLHAUS RICHARD
Published: July 2006

Fourteen patients were implanted with a single chamber dual sensor pacemaker (Legend Plus®) that measures minute ventilation (VE) via variations in impedance between a bipolar lead and the pacemaker case, and activity via a piezoelectric crystal bonded to the pacemaker case. Chronotropic incompetent patients were exercised an a treadmill and a bicycle in dual sensor mode. Activity only indicated pacing rate was measured using a strap‐on pacemaker. Both implanted and strap on pacemakers were adjusted to yield a steady‐state pacing rate of 100 beats/min during hall walk. Pacing rate, VE, and oxygen uptake (VO2) were measured continuously. Linear curve fit analysis slopes for plots of VE versus pacing rate during exercise (1.33‐1.49) compared favorably to values reported in normals. Peak pacing rates achieved for treadmill and bicycle testing for dual sensor mode were higher than activity mode alone. Slopes of heart rate to VE or VO2 were not significantly different (P < 0.05) for dual sensor mode in contrast to activity alone. In conclusion, the Legend Plus dual sensor rate adaptive pacing therapy delivered pacing rates more proportional to VE and VO2 under different types of exercise than rates indicated by a strap‐on pacemaker in activity mode.
Right Bundle Branch Block of Unknown Age in the Setting of Acute Anterior Myocardial Infarction: An Attempt to Define Who Should Be Paced Prophylactically
Authors: ROTH ARIE , BORSUK YOAV , KEREN GAD , SHEPS DAVID , CLICK AHRON , REICHER MEIR , LANIADO SHLOMO
Published: July 2006

It is widely accepted that patients presenting with acute anterior myocardial infarction and acute onset of right bundle branch block should be prophylactically paced in contrast with those who have a chronic bundle branch block. The admitting physician is faced with the dilemma of how to act if the age of this conduction disturbance is unknown. This problem has further intensified in recent years, with the introduction of thrombolytic treatment, where insertion of a central vascular line is associated with increased morbidity. The objectives of this study were to define clinical or electrocardiographic parameters that may help the admitting physician to decide whether patients presenting with an anterior wall myocardial infarction and a right bundle branch block of unknown age should be prophylactically paced. We examined prospectively the in‐hospital clinical course of 39 consecutive patients presenting with an acute myocardial infarction in whom the age of a right bundle branch block upon admission was unknown (group C, n = 39) and compared it with two similar groups of patients who presented with an acute right bundle branch block (group A, n = 38) and with a known chronic right bundle branch block (group B, n = 22). Thirty‐three patients (33%) died, with cardiogenic shock being the leading cause of death in the entire population. Prophylactic pacing, which was carried out in 66% and 54% of patients in groups A and C, respectively, did not reduce mortality rates. No clinical or electrocardiographic variables on admission were predictive to support prophylactic pacing in group C. In 10 of 46 (22%) patients who were prophylactically paced with a transvenous electrode, the following complications attributed to the procedure were detected: (1) either rapid sustained ventricular tachycardia (during implantation) that was unresponsive to overdrive pacing, or ventricular fibrillation necessitating electrical defibrillation (4 patients); (2) recurrent episodes of rapid nonsustained ventricular tachycardia, which stopped only after the pacemaker was turned off (1 patient); (3) complete AV block (1 patient); (4) fever appearing on the third or fourth day after implantation (3 patients); and (4) a large hematoma in the groin in 1 patient who was treated with thrombolysis shortly before pacemaker electrode insertion. Thus, the complications of transvenous temporary pacing in the era of thrombolysis may outweigh any theoretical advantage. (PACE 1995; 18:1496‐1508)
Pacemaker and Defibrillator Lead Entrapment: Case Studies
Authors: MAGNEY JEAN E. , PARSONS JONATHAN A. , FLYNN DAVID M. , HUNTER DAVID W.
Published: July 2006

Cadavers and cineradiographic analysis have been used to document the effects of the medial subclavicular musculotendinous complex (MSMC) upon lead function. Four cadavers with pacemakers were dissected and photographed to demonstrate the course a lead takes as it passes through the costoclavicular region. One lead had been placed into the cephalic vein. In the other three cadavers, leads placed by currently accepted techniques of subclavian venipuncture were all found to pass through the soft tissues of the subclavicular region before entering the venous system. Cineradiographic results from a patient with a defibrillator, taken before and after replacement of a broken lead, show the effect of clavicular motion on a lead that passes through the MSMC. Furthermore, cineradiography makes it possible to identify the point where the lead entered the vein, and whether or not it escaped being caught up in the soft tissues of the MSMC.
Feasibility of Radiofrequency Powered, Thermal Balloon Ablation of Atrioventricular Bypass Tracts Via the Coronary Sinus: In Vivo Canine Studies
Authors: FRAM DANIEL B. , BERNS ELLISON , ARETZ THOMAS , GILLAM LINDA D. , MIKAN JOSEPH S. , WATERS DAVID , McKAY RAYMOND G.
Published: July 2006

Radiofeequency catheter ablation of left sided accessory pathways is technically demanding and usually requires left heart catheterization. The feasibility of creating lesions from within the coronary sinus of sufficient size to ablate accessory pathways in humans using a thermal balloon catheter was studied in 20 dogs. In group 1 (n == 14), 17 thermal inflations were performed in 12 dogs at either 70°, 80°, or 90°C each for 30 or 60 seconds (in 2 dogs two non‐thermal control inflations were performed). Animals were sacrificed 6.3 ± 1.6 days later. In group 2 (n = 6), seven thermal inflations were performed at 90°C each for 180, 300, or 360 seconds. Group 2 animals received antiplatelet and anticoagulant therapy for 1 week and were sacrificed at 13 ± 10.7 days. In both groups, hemodynamic, angiographic, and electrocardiographic studies were performed at baseline, 1 hour after inflation, and prior to sacrifice. All dogs remained clinically stable throughout the procedure and no complications were attributed to the effect of thermal inflation. Thermal lesions measured 14.4 ± 4.4 mm in length and extended from the coronary sinus intima to a mean depth of 2.9 ± 1.2 mm (range 1.4‐6.5 mm). Group 2 lesions were significantly deeper than group 1 lesions (P = 0.03). Of the 24 thermal lesions created, atrial necrosis was present in 23 and ventricular necrosis in 11. In all lesions there was some degree of either atrial necrosis, ventricular necrosis, or both. A variable degree of coronary sinus thrombus was present in 18 dogs without clinical sequelae. It is concluded that radiofrequency balloon heating via the coronary sinus can create thermal lesions in the atrioventricular sulcus of dogs that may be of sufficient size to ablate accessory left‐sided pathways in humans. (PACE 1995; 18: 1518‐1530)
Transtelephonic Monitoring and Transmission of Stored Arrhythmia Detection and Therapy Data From an Implantable Cardioverter Defibrillator
Authors: FETTER JOSEPH G. , STANTON MARSHALL S. , BENDITT DAVID G. , TRUSTY JANE , COLLINS JOANNE
Published: July 2006

A new transtelephonic monitoring device designed for use with implantable Cardioverter defibrillators (ICDs) was evaluated. It is capable of interrogating ICDs and transmitting the following data via telephone: programmed parameters (e.g., ventricular tachycardia [VT] and ventricular fibrillation [VF] detection, therapies), number of VT and VF episodes, identification of successful therapies, the 20 cycle lengths preceding the last episode detected, the 10 cycle lengths after the last delivered therapy, battery voltage, and real‐time transmission of the patient's rhythm. Eighteen patients (mean age 64 ± 17years; 15 males) were implanted with an ICD and epicardial lead system. The patients who did not live near the primary hospital were provided with this transmitter and instructed to transmit monthly and whenever presyncope, syncope, or a shock were experienced. Five hundred ten episodes of spontaneous arrhythmia (495 VT, 15 VF) were detected in 14 of 18 patients in a 24‐month period and the success of each therapy (antitachycardia pacing, cardioversion 0.4‐34 J, defibrillation 34 J) was analyzed. The number of therapies delivered and their success (%) in terminating the arrhythmia were: 380 ramp/86%, 116 burst/84%, 119 cardioversion/57%, and 15 defibrillations/ 100%. Sixty‐three (42%) of the 152 transmissions indicated an arrhythmia. Twenty‐five (16%) of the 152 were transmitted because of symptoms. Sixteen (9.7%) of 165 VT episodes could not be terminated by the full set of programmed VT therapies. Analysis of the pre‐ and post‐episode intervals along with the patient's transmitted rhythm indicated that sinus tachycardia or atrial fibrillation were likely responsible for these episodes. The transmitted data included the real‐time ECG, which provided acute rhythm status plus stored data from the ICDs memory identifying the chronic arrhythmias detected, the therapies delivered, and the number and type of successful and ineffective therapies. This information provided the clinical data to the primary physician in order to determine the effectiveness of the programmed detection and therapy parameters and in some cases recommend to the home physician modifications to the device parameters or medication adjustments for enhanced arrhythmia control. We conclude that telephone transmission of stored ICD data is feasible and useful for patient management. It may obviate the need for patients experiencing symptoms to return to a site capable of device interrogation.
The Subcutaneous Array: A New Lead Adjunct for the Transvenous ICD to Lower Defibrillation Thresholds
Authors: HIGGINS STEVEN L. , ALEXANDER DIANA C. , KUYPERS CLAIRE J. , BREWSTER SCOT A.
Published: July 2006

Despite the benefits of transvenous implantable cardioverter defibrillators (ICDs), concern exists that patients with high defibriliation thresholds (DFTs) have an inadequate safety margin between the DFT and the maximum defibrillator energy. A new transvenous ICD lead adjunct, a subcutaneous lead array (SQ Array), was developed to increase safety margins by lowering DFTs. Composed of three lead elements joined in a common yoke, the SQ Array is tunneled subcutaneously in the left lateral chest. Serving as their own controls, 20 patients were studied intraoperatively comparing transvenous lead‐alone DFTs with lead‐SQ Array DFTs. Seventeen males and three females were randomized to receive the SQ Array through the CPI Ventak PBx/Endotak 70 series protocol. Mean patient age was 63.7 ± 2.5 years and mean ejection fraction 0.34 ± 0.04. DFTs were determined using a precise protocol of step‐down/step‐up testing commencing at 20 joules. Lead‐alone DFTs were tested using the proximal coil as the anode (+). For the lead‐SQ Array, the proximal coil and the array were linked as a common anode. The icad‐SQ Array resulted in a statistically significant reduction in mean monophasic DFT from 23.3 ± 2.3 joules (lead‐alone) to 13.5 ± 1.9 joules (lead‐SQ Array) (P < 0.001). Six patients had lead‐alone DFTs > 25 joules but did not require thoracotomy because of adequate DFT reduction with the SQ Array. We conclude that the SQ Array adjunct to the transvenous ICD lead lowers monophasic DFTs an average of 9.8 joules (40.6%) obviating the need for a thoracotomy in selected patients.
Effects of Nuclear Magnetic Resonance Imaging on Cardiac Pacemakers
Authors: LAUCK GERHARD , VON SMEKAL ALEXANDER , WOLKE STEPHAN , SEELOS KLAUS CHRISTIAN , JUNG WERNER , MANZ MATTHIAS , LUDERITZ BERNDT
Published: July 2006

Patients with cardiac pacemakers are currently restricted from nuclear magnetic resonance imaging (MRI), The aim of the study was to analyze the influence of MBI on new generation pacemakers. Tests were performed using a phantom model with seven dual chamber and two single chamber systems in a 0.5 Tesla MRI scanner. Monitoring by telemetry and oscillography were used during the standard clinical scan sequences as well as a pacemaker inquiry after each sequence. Spin echo, gradient echo, and fast field echo sequences were performed with the following stimulation modes: VVI, VVIR, VOO, DDD, DDDR, and DOO. On entering the static magnetic field, the reed switch was activated followed by asynchronous stimulation. The subsequent scan showed no influence on the stimulation function nor on the pacemaker program. Event counter function remained intact. Pacemakers with automatic mode switching to demand pacing or programmed inactivotion of the reed switch were triggered in the dual chamber mode and were inhibited in the one chamber mode during the scan. Alterations of pacemaker program or rapid pacing were not observed. MRI scan could induce voltage as high as intracardiac signals, but the stimulation threshold of the heart was not reached. Thus, pacemakers should be programmed in the asynchronous mode during scan to avoid inhibition and trigger mechanism.
Suppression of Ventricular Output by Noise in the Atrial Channel in a Dual Chamber Pacemaker
Authors: BEN‐ZUR URI M. , KAHN SHOSHANAH , GROSS JAY N. , PLATT SIMIE B. , GOODFRIEND* MICHAEL A. , FURMAN SEYMOUR
Published: July 2006

In a pacemaker dependent, 60‐year‐old man with complete heart block, programming high (5.0 V and 1.0 ms) atrial output and 5.0 volt and 0.5 ms ventricular output while in the DDD mode of a pulse generator, resulted in loss of ventricular channel output with resulting asystole, while the simultaneous, pulse generator produced ECG interpretation channel falsely indicated continuing ventricular channel output. Ventricular pacing was promptly restored by programming to the emergency VVI mode. At later operation the atrial lead was determined to be defective, with a low impedance, while the ventricular lead was intact (lead impedance telemetry was not available). The manufacturer has acknowledged a pulse generator design anomaly that may occur in the setting of a low atrial impedance and issued a Health Safety Alert.
Erroneous Discharge of an Implantable Cardioverter Defibrillator Caused by an Electric Razor
Authors: SEIFERT THOMAS , BLOCK MICHAEL , BORGGREFE MARTIN , BREITHARDT GÜNTER
Published: July 2006

We report an unusual case of the erroneous discharge of a third‐generation multiprogrammable implantable Cardioverter defibrillator in a 64‐year‐old patient with a history of recurrent ventricular tachycardias caused by electromagnetic interference while shaving with an electric razor. Electromagnetic interference was related to a defect in the electrode's insulation and could not be provoked in an intact electrode.
Electromagnetic Interference of Analog Cellular Telephones with Pacemakers
Authors: BARBARO VINCENZO , BARTOLINI PIETRO , DONATO ANDREA , MILITELLO CARMELO
Published: July 2006

The aim of this study was to verify whether there is a public health risk from the interference of analog cellular telephones with pacemakers. We used a human trunk simulator to reproduce an actual implant, and two cellular telephones working with the TACS (Total Access Communication System) standard. Results showed that the electromagnetic field radiated from the analog cellular telephones interfered with a large number of the pacemakers tested (10/25). When the telephone antenna was in close proximity to the pacemaker head, pacemaker desensitizing and sensitizing and pulse inhibition was detected at the moment of an incoming call and throughout ringing. In the worst case of pulse inhibition, the pacemaker skipped three nonconsecutive beats and then resumed its normal pacing, while the desensitizing and sensitizing phenomena persisted as long as the interfering signal was on. Pulse inhibition was also observed when the connection did not succeed. Maximum sensing threshold variation was about 186% (increase) and 62% (decrease) for desensitizing and sensitizing phenomena, respectively. It was also demonstrated that the signal emitted by analog cellular telephones during the crossing of contiguous cells could induce pacemaker pulse inhibition, but under our experimental conditions this event did not seem to pose a risk for the pacemaker patient.
State of the Science:Pacemaker and Defibrillator Interference from Wireless Communication Devices
Authors: HAYES DAVID L. , CARRILLO ROGER G. , FINDLAY GRETCHEN K. , EMBREY MARTHA
Published: July 2006

The use of wireless communication devices has increased rapidly, with current industry estimates of 50,000,000 subscribers of cellular telephone services, a number that is expected to double by the year 2000. Because wireless communication devices emit RF signals, they have the potential to interfere with implantable devices. The mechanisms of interference and the magnitude of interference must be considered in terms of the type of wireless communication device being used and the characteristics of the individual implantable device that is exposed to the RF emission of the cellular phone. This article reviews the potential effects of wireless communication devices on implantable devices and makes initial recommendations for patients with implantable devices.
Electromagnetic Interference of Pacemakers by Mobile Phones
Authors: IRNICH WERNER , BATZ LOTHAR , MÜLLER REINHOLD , TOBISCH ROLF
Published: July 2006

The topic of interference of pacemakers by mobile phones has evoked a surprisingly strong interest, not only in pacemaker patients, but also in the public opinion. The latter is the more surprising, as in the past, the problem of interference has scarcely found the attention that it deserves in the interest of the patient. It was the intention of our investigation to test as many pacemaker models as possible to determine whether incompatibility with mobile phones of different modes may exist, using an in vitro measuring setup. We had access to 231 different models of 20 manufacturers. During the measurements, a pulse generator together with a suitable lead was situated in a 0.9 g/L saline solution, and the antenna of a mobile phone was positioned as close as possible. If the pulse generator was disturbed, the antenna was elevated until interference ceased. The gap in which interference occurred was defined as “maximum interference distance.” All three nets existing in Germany, the C‐net (450 MHz, analogue), the D‐net (900 MHz, digital pulsed), and the E‐net. (1,800 MHz, digital pulsed) were tested in succession. Out of 231 pulse generator models, 103 pieces corresponding to 44.6% were influenced either by C‐ or D‐net, if both results were totaled. However, this view is misleading as no patient will use C‐ and D‐net phones simultaneously. Separated into Cor D‐net interference, the result is 30.7% for C or 34.2% for D, respectively, of all models tested. The susceptible models represent 18.6% or 27% of today's living patients, respectively. All models were resistant to the E‐net. With respect to D‐net phones, all pacemakers of six manufacturers proved to be unaffected. Eleven other manufacturers possessed affected and unaffected models as well. A C‐net phone only prolonged up to five pacemaker periods within 10 seconds during dialing without substantial impairment to the patient. Bipolar pacemakers are as susceptible as unipolar ones. The following advice for patients and physicians can be derived from our investigations: though 27% of all patients may have problems with D‐net phones (not C‐ or E‐net), the application should generally not be questioned. On the contrary, patients with susceptible devices should be advised that a distance of 20 cm is sufficient to guarantee integrity of the pacemaker with respect to hand held phones. Portables, on the other hand, should have a distance of about 0.5 m. Pacemaker patients really suffering from mobile phones are very rare unless the phone is just positioned in the pocket over the pulse generator. The contralateral pocket or the belt position guarantees, in 99% of all patients, undisturbed operation of the pacemaker. A risk analysis reveals that the portion of patients really suffering from mobile phones is about 1 out of 100,000. Nevertheless, it would be desirable in the future if implanting physicians would use only pacemakers with immunity against mobile phones as guaranteed by the manufacturers