bluuebunny/crossref_metadata_2025 huggingface dataset:
Catheter Ablation for Recurrent Tachyarrhythmias. Clinical Experience with Two Different Techniques of Ablation in 21 Patients
Authors: GOY J.J. , VOGT P. , FROMER M. , KAPPENBERGER L.
Published: July 2006

Between 1984 and 1988, 21 patients underwent catheter ablation for drug refractory arrhythmias. Nine patients presented atrial flutter, atrial fibrillation or atrial tachycardia, nine had supraventricular tachycardia (one AV nodal reentrant tachycardia, one reciprocating tachycardia due to concealed accessory pathway and seven XMPW syndrome). Three had ventricular tachycardia. Fourteen patients were treated with direct current shock ablation (DC) and seven patients with radiofrequency ablation (RF). Eight patients underwent ablation of the His bundle. In six patients permanent AV block could be induced and in two first‐degree AV block. All became asymptomatic (two with additional antiarrhythmic drug therapy). In four patients with WPW syndrome DC ablation of the accessory pathway was attempted. In one patient a permanent block in the accessory pathway and in another an intermittent block were obtained. In the two remaining patients with accessory pathways the ablation failed to interrupt the retrograde conduction in one the retrograde conduction was modified: however, in the other no change could be demonstrated. Two patients underwent ventricular foci ablation, with one partial success (arrhythmia controlled with associated drug therapy) and one failure. Three patients had RF His bundle ablation (two for atrial flutter and one for atrial fibrillation). One complete atrioventricular block, one first degree AV block and one first degree AV block associated with right bundle branch block were induced. Recurrence of tachyarrhythmias was prevented only in the patient with complete atrioventricular block. RF ablation of accessory pathway was performed in three patients. It resulted in anterograde block in the accessory pathway in the first patient; a slight modification of the retrograde refractory period in the second and no change was noted in the last one. The first of these three patients could then be controlled with drug therapy. The other two patients underwent surgical dissection of the pathway. One patient underwent an unsuccessful attempt of ventricular focus ablation with RF energy. Complications were more common with DC than with RF ablation but serious ventricular arrhythmias were also observed during RF ablation. Thus, DC ablation was completely successful in eight of 14 patients (57%), partially successful with the addition of drug therapy in three patients (21%) and failed in 22%. HF ablation was successful in only one patient (14.5%) and partially successful in another one (14.5%). This relatively low success rate is due in part to the design of the device and the electrodes used in this study. With technical improvements of RF ablation it seems reasonable to expect that this method will play a significant role in the management of drug refractory arrhythmias, since RF ablation, when compared to DC ablation, has the major advantage not to require general anesthesia during the procedure.
Predictive Value of Various Types of Ventricular Response to Programmed Ventricular Stimulation: Relation to Holter Monitoring
Authors: WNUK‐WOJNAR ANNA‐MARIA , GIEC LESZEK , DRZEWIECKI JANUSZ , TRUSZ‐GLUZA MARIA , SZULC ANDRZEJ
Published: July 2006

The study was performed to determine the predictive value of programmed stimulation for identification of pts with ventricular arrhythmias: 75 patients were studied by means of 24‐hour ambulatory ECG (24 ECG) and programmed right (in some patients also left) ventricle stimulation at sinus and two or three pacing rates using two (standard) and three extrastimuli or burst stimulation (extensive protocol). Lown classes 0.1–3 and 4a–4h were observed in 24 ECG in 35, 14, and 26 patients, respectively. In programmed stimulation 1–6 repetitive ventricular responses (RVR) were found in 56 pts, nonsustained ventricular tachycardia in 11 and sustained ventricular tachycardia in 21 pts. High incidence of induced VT was found in pts with complex ventricular arrhythmia in 24 ECG, 81% of this group, in all but six pts only standard protocol was used. The 1–6 RVR were observed in almost 40% of pts without any arrhythmia. Conclusion; Only VT induction is a useful index for high risk patients.
Drug Therapy for Survivors of Sudden Cardiac Death
Authors: HOROWITZ LEONARD N.
Published: July 2006

The proliferation of standard as well as novel community based systems for resuscitation of victims of out‐of‐hospital cardiac arrest has provided a large group of sudden cardiac death survivors who present a therapeutic challenge. The nature and severity of the underlying heart disease must be delineated. Particularly, myocardial ischemia and congestive heart failure must be controlled. Prior to considering device therapy of surgical intervention, pharmacologic therapy should be evaluated. Baseline electrophysiological studies determine the applicability of serial pharmacologic testing. In patients with inducible VT/VF, serial electrophysiological testing can identify drug regimens that prevent the arrhythmia in approximately 40% of patients. In an additional 20% of patients, regimens which slow the ventricular tachycardia and significantly reduce the arrhythmia related mortality can be identified. Three to 5‐year follow‐up has shown such an approach can reduce the sudden death mortality in these patients to less than 3% per year. It has been suggested that certain medication, most notably amiodarone, electrophysiological testing has not been useful in assessing efficacy. Several recent studies, however, have shown that electrophysiological testing is indeed useful even in evaluating the efficacy of amiodarone. In patients in whom ventricular tachycardia/ventricular fibrillation cannot be prevented or significantly slowed, medical therapy is generally ineffective and the sudden death mortality is 20% to 40% per year. In such patients, other therapeutic modalities should be considered.
Improved Survival from Cardiac Arrest in the Community
Authors: HEARNE THOMAS R. , CUMMINS RICHARD O.
Published: July 2006

We now know that the elements required to achieve the highest survival rates from out‐of‐hospital cardiac arrest include: witnessed arrest, rapid telephone notification of the emergency medical service, early initiation of cardiopulmonary resuscitation, rapid arrival within minutes of emergency personnel equipped with a defibrillator, and early advanced airway management and intravenous pharmacology. In the United States, and in several other countries innovative approaches have been tried to bring all these elements together in one system. These approaches include community‐wide CPR training programs, telephone‐assisted CPR instruction delivered at the time of a cardiac arrest, early defibrillation performed by family members of high risk patients, early defibrillation performed by minimally trained community responders, and early defibrillation performed by minimally trained ambulance personnel. Controlled, prospective studies have demonstrated the effectiveness and practicality of all of these approaches. New studies are in progress with the prehospital use of early transcutaneous cardiac pacing and these show promise. This article reviews the evidence that supports these multi‐layered and innovative approaches to the treatment of out‐of‐hospital cardiac arrest.
Reduction of Energy Required for Defibrillation by Delivering Shocks in Orthogonal Directions in the Dog
Authors: BARDOU ALAIN L. , DEGONDE JEAN , BIRKUI PIERRE J. , AUGER PIERRE , CHESNAIS JEAN‐MICHEL , DURIEZ MICHELINE
Published: July 2006

Reduction of energy required to defibrillate (ERD) seems to represent a necessary condition for intensive development of implantable defibrillator, so as for minimization of cardiac and pulmonary damages provoked by high energy transthoracic defibrillation electric shocks. The present work describes a defibrillation method using shocks delivered in orthogonal directions and separated by a 100 ms delay. Defibrillation threshold measured with classical unidirectional shocks on 30 dogs has been found to be 286.8 ± 22.2 joules. In the same animals, defibrillation threshold measured by use of orthogonal shocks has been found to be 101.4 ± 14.9 joules. We conclude that this crossed shocks method leads to a substantial reduction of ERD (64%).
Defibrillation Current and Impedance are Determinants of Defibrillation Energy Requirements
Authors: DORIAN PAUL , WANG MICHELE J.
Published: July 2006

The relationship between various electrical descriptors of shocks for cardiac defibriliation is incompletely understood. Defibrillating energy, current, impedance and pulse duration were measured in 18 dogs. They were subject to repeated fibrillation‐defibrillation through epicardial patches, with shocks of preset energy and voltage and variable pulse duration, impedance and peak current. Current and energy requirements for defibrillation were calculated. Energy requirements were positively correlated with pulse duration and interelectrode impedance (r = .70, P < 0.01). Correcting for heart weight, these correlations were no longer present. However, peak current was correlated with energy requirements both before (r = ‐0.62, P < 0.05) and after (r = ‐0.76, P < 0.01) correcting for heart weight, with energy requirement decreasing as peak current/g heart increased. Current requirements were significantly less variable between animals than energy requirements (.027 ± .012 joules/g vs .016 ± .003 Amps/g), suggesting that current per unit heart weight may be a better descriptor than energy/or the ability to defibrillate.
A Model to Evaluate Alternative Methods of Defibrillation Threshold Determination
Authors: CHURCH TIMOTHY , MARTINSON MELISSA , KALLOK MICHAEL , WATSON WARREN
Published: July 2006

The voltage (or, equivalently, energy) at which defibrillation occurs for a specific episode of fibrillation can be represented by specifying or estimating the probability of successful defibrillation for each voltage or energy. This relation of voltage to probability is the probability function. For a series of attempts, the probability function predicts the frequency with which defibrillation will occur at a given voltage. By defining the defibrillation threshold (DFT) as the voltage at which the probability function takes on a specific value, say 50%, a method of defibrillation threshold determination can be evaluated by how accurately and precisely it estimates the “true” defibrillation threshold. By utilizing estimated probability functions from animals and humans, the relative performance of different methods of defibrillation threshold determination can be evaluated. Three methods were evaluated using published animal data and human clinical data: (1) stepping down to the first voltage that fails; (2) stepping up to the first voltage that succeeds; and (3) doing both 1 and 2 and averaging. In all cases, Method 3 has lower total error. Definitions of defibrillation threshold other than the 50% level can also be evaluated in this fashion.
Transvenous and Subcutaneous Electrode System for an Implantable Defibrillator, Improved on Large Pigs
Authors: CANSELL A. , LECHAT PH. , FONTAINE G. , GROSGOGEAT Y. , MEYER‐WAARDEN K.
Published: July 2006

The currently required surgical procedure for implantable defibrillator implantation is a limiting factor and several groups are therefore investigating transvenous approaches. Our electrode system consists of a nondistal right ventricular catheter electrode and two or three subcutaneously (SC) placed electrodes. An optimal location for these SC electrodes is important to obtain the lowest possible defibrillation threshold (DFT) by allowing a more homogeneous current distribution within the thorax. An empirical approach consists of placing randomly the SC electrodes to find out the lowest possible DFT. A mathematical approach is to calculate the SC electrode locations for an optimal electric field distribution by using magnetic resonance images of thorax cross‐sections and a specially designed computer program. Our recent experimental results are based on a series of 15 pigs weighing between 60 and 102 Kg. DFT ranged between 10 and 26 joules. We conclude that an electrode system with a right ventricular electrode and two or three subcutaneous electrodes can be optimized to reach a DFT for pigs with human‐near body weights which is compatible with the energy capabilities of our implantable device.
Mechanism of Death in Patients with the Automatic Implantable Cardioverter Defibrillator
Authors: LUCERI RICHARD M. , HABAL SALEM M. , CASTELLANOS AGUSTIN , THURER RICHARD J. , WATERS RAYMOND S. , BROWNSTEIN SHELDON L.
Published: July 2006

Fifty patients underwent primary implantation of an automatic implantable cardioverter defibrillator between August 1983 and April 1988 and were entered into a long‐term surveillance program. There were a total of 14 deaths (28%) in the entire group occurring at a mean of 8.7 months postimplantation. Eleven deaths were cardiac and three were noncardiac (two pneumonia, one leukemia). The group of deceased patients were similar to the survivors in all respects except for a statistically lower ejection fraction (23% vs 32%) at the time of implantation. In addition, 13/14 (93%) of the deceased patients experienced at least one appropriate AICD discharge at a mean of 4.5 months post implantation. Recorded ECGs at the time of death revealed that most of the sudden deaths were due to electromechanical dissociation and not to AICD‐treatable arrhythmias. These data suggest therefore that death in AICD patients is usually cardiac, due primarily to low ejection fraction and occurs in patients who have previously received AICD discharges.
Development of a Clinical Database for the Implant and Follow‐up of Cardioverter Systems
Authors: BENEDEK Z. MICHAEL , FURMAN S.
Published: July 2006

The purpose of a clinical database in AICD follow‐up is twofold: to follow the evolution (1) of the patient and (2) of the implanted hardware. The pacemaker implant is performed the same day, whereas the implant of a complete AICD system can span over several days or even weeks. Therefore the first design criteria for the database is to clearly identify a single procedure. AICDs require the use of several leads of different types and functions and each lead has to be followed independently. Therefore the second design criteria is to establish a continuous history for each device implanted. To accomplish this the following method has been devised. The implant patient has a single demographic form and for each new procedure a ‘Purpose of Procedure’ form is filled out, which is identified by the date the form was initiated and by the patient's ID number. There are separate forms for the defibrillator and for three types of leads (transvenous, epicardial sensing and patch leads). For each hardware implanted a specific form is filled out and keyed to the ‘Purpose of Procedure’ form. Consequently the patient is monitored through the sequence of ‘Purpose of Procedure’ forms, the defibrillator and the leads through the hardware forms. Stimulation and sensing threshold measurements are part of the respective hardware forms but the induced tachycardia measurements are separate. At present 56 AICDs have been followed in the database.
Lithium/Silver Vanadium Oxide Batteries for Implantable Defibrillators
Authors: TAKEUCHI ESTHER SANS , QUATTRINI PAUL J. , GREATBATCH WILSON
Published: July 2006

Lithium/silver vanadium oxide (SVO) batteries have been under development in these laboratories since 1980. The system consists of a lithium anode, a liquid organic electrolyte, a cathode composed of conductive additives, a binder, and silver vanadium oxide, a vanadium oxide bronze produced by the thermal decomposition of vanadium oxide and silver nitrate. High rate batteries/or implantable cardiac defibrillators based on this chemistry have been under development since 1984. The first Li/SVO defibrillator battery introduced was the Model 8512 with a theoretical capacity of 5.5 Ah and dimensions of 52 mm × 33 mm × 13.5 mm. Later, the Model 8615 was introduced. This cell has a theoretical capacity of 3.0 Ah and dimensions of 52 mm × 21 mm × 13.5 mm. Two other cells which are proprietary have also been introduced. All of the cells can deliver pulses of up to 2.0 amps from a microampere background. The self‐d is charge of the cells has been shown to be less than 2% per year. In addition, the silver vanadium oxide chemistry provides a discharge curve whose voltage decreases with depth of discharge. This feature can be used as a state‐of‐charge indicator. The cells have been subjected to rigorous environmental and abuse testing and have been found to have characteristics suitable for implantable applications.
Termination of Malignant Ventricular Tachycardias by Use of an Automatical Defibrillator (AICD) in Combination with an Antitachycardial Pacemaker
Authors: GREVE H. , KOCH TH. , GÜLKER H. , HEUER H.
Published: July 2006

We implanted an “Automatic Impiantable Converter‐Defibrillalor” (AICD) and as far as useful an antitachycardial pacemaker (Intertach) in addition in 11 patients suffering from malignant ventricular tachycardias via a median sternotomy. In eight cases a coronary artery disease and in three cases a dilatative myopathy was the intrinsic disease. During surgery in all patients we attempted to trigger ventricular tachycardias and their termination by programmed stimulation. This procedure was successful in nine patients who received an antitachycardial pacemaker system. After the wounds healing, repeated induced ventricular tachycardias in all patients, who received a combination of the systems, could be terminated by the antitachycardial pacemaker prior to an intervention of the implanted defibrillator.
Implantable Defibrillation: Eight Years Clinical Experience
Authors: THOMAS ANDRA C. , MOSER SUZAN A. , SMUTKA MARK L. , WILSON PHYLLIS A.
Published: July 2006

Implantation of the first automatic defibrillator occurred in February 1980. Incorporation of cardioversion capability in 1982 resulted in the AICD™ automatic implantable cardioverter defibrillator. Between April 1, 1982 and April 15, 1988, 3610 patients in 236 U.S. and 84 international centers received AICD pulse generators. Patient population consisted of 2904 males and 683 females with recurrent ventricular tachycardia and/or fibrillation, mean age 59 yrs. (range 9–96 yrs.). Primary diagnoses reported for the patient group were: coronary artery disease (63.5%), nonischemic cardiomyopathy (12.9%), other (6.4%) and unspecified (17.2%). Mean reported LV ejection fraction was 32.8%. Follow‐up averaged 12.2 mo. (range 0–72 mo.). Of 385 deaths, 94 (24%) were sudden. Cumulative percentage survival (±S.E.) from sudden cardiac death (SCD) was 98.0 ± 0.3%, 96.5 ± 0.5%, 95.2 ± 0.7%, 93.7 ± 1.0%, 93.7 ± 1.0% and 89.7 ± 4.0% at 12, 24, 36, 48, 60 and 72 months, respectively. Operative mortality (30 days) was 2.5%. Reported side effects/complications were similar to those of pacemakers. To date, 33% of the patients received spontaneous device countershocks. AICD pulse generator survival from electrical and mechanical failures was 92.8 ± 0.5%, 88.4 ± 0.7%, 86.7 ± 0.8% and 86.4 ± 0.9% at 12, 18, 24 and 30 mos. Data analysis demonstrates that the AICD has had a significant impact on patient survival from SCD.
Survival of Patients with the Automatic Implantable Cardioverter Defibrillator
Authors: MERCANDO ANTHONY D. , FURMAN SEYMOUR , JOHNSTON DEBRA , FRAME ROSEMARY , BRODMAN RICHARD , KIM SOO G. , FISHER JOHN D.
Published: July 2006

Between May 1982 and May 1988, 37 patients (28 males and 9 females, mean age 57.6, range 16–76 years) of approximately 600 evaluated for sustained ventricular tachycardia and/or fibrillation (VT/VF) were treated with an automatic implantable cardioverter defibrillator (AICD). Twenty‐eight of the patients had coronary artery disease, 7 had nonischemic cardiomyopathy, 1 had amyloid hear disease, and 1 had rheumatic heart disease. The mean ejection fraction was 32.2 ± 12.9% (range, 9–64%). Eleven patients have died at a mean of 16.7 months after implantation. The cumulative survival rate was 81% at 1 year, 77% at 2 years. 68% at 3 years, and 53% at 4, 5, and 6 years. Considering only sudden deaths, the survival was 97% at 1 and 2 years, 90% at 3 years, and 80% at 4, 5, and 6 years. Twenty‐one of the 37 patients received spontaneous shocks. If the first shock marks the time to death in the absence of an AICD, the cumulative survival rate would have been 56% at 1 year, 42% at 2 years, 29% at 3 years, and 14% at 4, 5, and 6 years. The maximum amount of time to a first appropriate shock was 39.7 months. Thirty‐nine devices have been explanted; 28 for battery depletion; 5 for infections; 3 for improper sensing; 2 for electronic failure; and 1 at the time of cardiac transplantation. The average time to failure of the 28 units removed for battery depletion was 19.8 ±6.9 months. We conclude that in this group of patients, short‐term survival is increased by AICD implantation, hut long‐term survival remains poor. Incidence of sudden death is reduced to 3% at 1 and 2 years, 10% at 3 years, and 20% after 4 years. Other patient selection criteria may be useful in selecting those patients whose survival will be improved by the AICD.
Computer‐Assisted Pacemaker Management Systems: Three Years of Clinical Experience
Authors: KÜHL MARTIN , KREUZER JOACHIM , ZEGELMANN MAX
Published: July 2006

The implantation of large numbers of cardiac pacemakers and the increasing sophistication in engineering techniques has resulted in the demand for computer‐assisted pacemaker management systems to remain on top of the available programmable features of the pacers as well as being able to access the follow‐up data of pacemaker patients. A pacemaker patient management systems is introduced (PATIENTLOG™) that has been used in the clinical environment for a number of years. The menu‐guided program is easy to handle and features a patient card for administration data, an implantation card for the technical data of the pacer, and a follow‐up card where a large number of follow‐ups can be stored side by side which are easily graphically displayable. An extensive statistical program, letter functions, automatic back‐up and on‐line communication with external equipment through an RS 232C interphase and a parallel adapter are available. The data base in Frankfurt holds 8,000 patients, 10,000 interventions and more than 30,000 follow‐ups, the existing data base needs 20 M bytes storage space. Up to 96 different pacer types with their specific features can be introduced into the system. Software and hardware design complies with the recommendation of the NASPE Computer Committee.
Antihypertensive Therapy for the Elderly: An Expert System to Assist Therapeutic Decisions
Authors: GONDEK K. , LAMY P.P. , SPEEDIE S.M. , JEFFREY P.L.
Published: July 2006

The prevalence of hypertension among the elderly is high. Recent multicenter studies have shown hypertension, especially isolated systolic hypertension, to be a risk factor and treatment to be elective, if individualized. In addition, the presence of multiple complicating conditions and the need for multiple medications in the elderly increases the required medical knowledge base necessary to appropriately determine antihypertensive therapy. To assist the primary provider, an expert system has been developed that provides advice on therapeutic decisions for elderly patients (greater than 65 years old and less than 85 years old). It takes into account such factors as age, sex, lifestyle, site of care, nutritional status, physiologic and pathophysiologic changes, co‐existing diseases, multiple drug use, and prior antihypertensive drug exposure and response. The system user enters patient characteristics, disease states, risk factors, relevant laboratory values, and prior drug therapy. The system responds with a set of recommendations of appropriate therapy individualized for the specific patient. To further assist the process, relative costs of therapy are also included. The system, consisting of over 200 rules, is currently undergoing validation by a panel of cardiologists. It is implemented in IBM's Expert System Environment (ESE) on the IBM 4341. The authors wish to acknowledge the contribution of the ESE software by the IBM Corporation.
Diagnosis of Paced Electrocardiograms by Inverse Computer Modeling of Pacemaker Actions
Authors: MALIK MAREK , CAMM A. JOHN
Published: July 2006

The explanation and interpretation of ECGs recorded from paced patients may be very difficult because of pacemaker specification, programmed parameters, and idiosyncrasy and also because of hidden interactions between the device and its environment. Moreover, the recent development of very sophisticated pacemakers makes the heart‐pacemaker interaction (HPJ) difficult to understand even when the recorded ECG is accompanied by an event marker. A computer system providing an automatic analysis of the HPJ based on ECG data has been developed and implemented on an IBM PC AT computer. The system evaluates all possible combinations of HPI events and establishes whether they correspond to the pacemaker. The system inputs interactively the description of the pacemaker mode and programming, and the description of the analyzed ECG in the form of timing of “definite” and “possible” sensing events and generator pulses. The computer performs the analysis and establishes whether the device operates correctly within its permitted error. The system has been tested by evaluating different examples of paced ECGs. The presented examples confirm the ability of the system and show the potential for its future clinical use. Future development of the system and the provision of computer support for the understanding of the HPI of complex DDDR pacemakers are discussed.
Evaluating Antiarrhythmic Strategies: A Knowledge‐Based System for Exploring Clinical Data
Authors: PORENTA G. , BINDER T. , PFAHRINGER B. , ANVARI A. , WEBER H.
Published: July 2006

Medical therapy for cardiac arrhythmias is still to a large extent based on empirical methods. Assessing and evaluating different therapeutical strategies constitutes the starting point for inducing decision methods to select the appropriate regimen for an individual patient. We designed a computer‐based system that establishes a set of heuristic rules linking attributes in a data base of patients with rhythm disturbances. A feasibility analysis conducted on a small set of 23 patients indicated that constraints on the number of attributes and their clinical relevancy together with a representation scheme for temporal changes have to be incorporated to provide for a useful and efficient algorithm.
Fundamental Considerations in Pacing of the Diaphragm for Chronic Ventilatory Insufficiency: A Multi‐Center Study
Authors: GLENN WILLIAM W. L. , BROUILLETTE ROBERT T. , DENTZ BEZALEL , FODSTAD HARALD , HUNT CARL E. , KEENS THOMAS G. , MARSH H. MICHAEL , PANDE SANGAM , PIEPGRAS DAVID G. , VANDERLINDEN R. GRAHAM
Published: July 2006

Records were reviewed of 477 patients who had diaphragm pacemakers implanted for treatment of chronic hypoventilation. Three groups were established for comparison. (1) Center group: 165 patients operated on in six medical centers participating in a cooperative study; (2) Noncenter group, sufficient data available: 203 patients operated on by surgeons with experience limited to a few cases; (3) Nonstudy group, minimal data available: 109 patients operated on as in group 2; vital statistics only were contributed. The protocol for data gathering was comprised of 154 major variables. Basic data on age, sex, diagnosis and etiology were analyzed for homogenicity of data among the groups. A comprehensive analysis of the pacing methods, complication and results fom the Center group yielded information on the early experience with diaphragm pacing important to its future application.
Long‐Term Neurostimulation of Skeletal Muscle: Its Potential for a Tether‐Free Biologic Cardiac Assist Device
Authors: ANDERSON WILLIAM A. , BRIDGES CHARLES R. , CHIN ALVIN J. , ANDERSEN JAMES S. , ACKER MICHAEL A. , HAMMOND ROBERT L. , DIMEO FREDERICK , CAHALAN PATRICK T. , GALE DENNIS R. , BROWN WENDY E. , STEPHENSON LARRY W.
Published: July 2006

Skeletal muscle has a tremendous capacity to adapt. This adaptive phenomenon is seen perhaps to the greatest extent when skeletal muscle is subjected to chronic low frequency stimulation via the motor nerve. There is a decrease in glycolytic enzymes and an increase in oxidotive enzymes, as well as a change in the contractile proteins and an increase in the mitochondrial volume fraction of the muscle fiber. These adaptive changes result in a muscle that is considerably more fatigue‐resistant. Specifically herein, we report on a pneumatic aortic counterpulsator device powered by skeletal muscle. These muscle pumps functioned continuously and pumped blood effectively in tether‐free animals for several weeks.
Diaphragm Pacing in Infants and Children
Authors: HUNT CARL E. , BROUILLETTE ROBERT T. , WEESE‐MAYER DEBRA E. , MORROW ANNA , ILBAWI MICHEL N.
Published: July 2006

Since 1976 we have implanted bilateral diaphragm pacers in 34 infants and children: 26 with central hypoventilation syndrome (CHS), three with myelomeningocele, and five with quadriplegia. Compared to adults, several modifications have been necessary to achieve effective ventilation in infants and younger children. In all instances, a tracheostomy has been necessary due to impaired neuromuscular control of upper airway patency during pacing. Bilateral pacing has been necessary to achieve adequate ventilation; in the CHS children with normal awake ventilation, bilateral pacing during sleep eliminates the need for positive pressure ventilation. For the remaining children, adequate awake ventilation is achieved with bilateral pacing, thus permitting substantially greater mobility and limiting use of the ventilator to sleep time. Our longest survivor has now been paced for 10.7 years, and in no instance has phrenic nerve damage occurred secondary to electrical stimulation‐ Our current pacing regime is characterized by moderate respiratory rates (21 breaths/min), long interpulse intervals (95 ms), and short inspiratory times (0.6 sec), resulting in 50%‐75% fewer stimuli/min compared to our previous regime. For all infants and children requiring 24‐hour ventilatory assistance, our recent successes in maintaining ventilation using significantly fewer stimuli suggest that long‐term continuous pacing is a realistic future goal.
Cardiac Pacing and Valvular Surgery
Authors: GAILLARD D. , LESPINASSE P. , VANETTI A.
Published: July 2006

Over a 17‐year period (1970–1987) 75 patients, 3 % of overall valvular surgery (VS) patients have been permanently paced at the time of VS (group 1), nine have been paced long after (group 2), 12 were already paced at the time of valve replacement (group 3), and 81 had a permanent pacing lead inserted during VS without further need for permanent pacing (group 4). Based on pre‐, per‐ and post‐operative clinical and electrocardiographic data we studed these four groups (GR). Aortic disease and especially calcified aortic stenosis (CAS) are the main valvular pathologies in all GR. The survival rate in GR 1 is lower than the survival rate of our overall VS PT5 due to older average ages and more severe cardiac conditions. In five patients GR 2 a myocardial pacing lead placed during VS was used long after for permanent stimulation. Patients in GR 3 were older than in other CR at the time of VS. The mortality was high in the patients operated on between 1973 and 1978 (average survivd 3.5 years after pacing/2 years after VS) thus demonstrating the benefit of myocardial protection. For GR 4 the ratio of permanent lead implantation during VS was high in the late seventies (10%), it is now around 0.5%. In cases where the evolution of peroperative conduction disturbances is doubtful, it seems to us simpler to place a myocardial lead avoiding subsesuent endocardial pacing if necessary, later, especially in patients with tricuspid disease.
Entrapment of Tined Leads
Authors: RES JAN C.J. , DE COCK CAREL C. , VAN ROSSUM ALBERT C. , SCHREUDER JOSIEN
Published: July 2006

RES, J.C.J., et al.: Entrapment of Tined Leads A rare complication is described, in three patients. The tined tip of a ventricular pacemaker electrode was entrapped in the chordae of the tricuspid valve and could not be removed by subtle manipulations in two patients. In one patient, the electrode was removed with partial rupture of the tricuspid valve. The two electrodes remained in the entrapped position and new electrodes were inserted in all three cases. No clinical sequelae were found during follow‐up of at least 24 months.
Diagnosis of Coronary Sinus Diverticulum in Wolff‐Parkinson‐White Syndrome Using Coronary Angiography
Authors: STAMATO NICHOLAS , GOODWIN MARK , FOY BRYAN
Published: July 2006

STAMATO, N. et al.: Diagnosis of Coronary Sinus Diverticulum in Wolff‐Parkinson‐White Syndrome Using Coronary Angiography The entity of Wolff‐Parkinson‐White Syndrome and coronary sinus diverticula when the bypass tract is posteroseptal in location has been described recently. The presence of this diverticulum may complicate arrhythmia surgery and could potentially add to the risk of catheter ablation. We describe a case of Wolff‐Parkinson‐White Syndrome in which the diagnosis of a coronary sinus diverticulum was made preoperatively using late‐phase coronary angiography and suggest angiography be considered in patients with posteroseptal bypass tracts prior to surgery or catheter ablation.
Lower Chronic Stimulation Threshold in the Carbon‐Tip than in the Platinum‐Tip Endocardial Electrode: A Randomized Study
Authors: THUESEN LEIF , JENSEN PETER JOERN , VEJBY‐CHRISTENSEN HANS , MORTENSEN PETER THOMAS , THOMSEN POUL ERIK BLOCH
Published: July 2006

THUESEN, L., et al.: Lower Chronic Stimulation Threshold in the Carbon‐Tip Than in the Platinum‐Tip Endocardial Electrode: A Randomized Study Seventy‐nine patients admitted for VVI pacemaker treatment were randomly given a Siemens‐Elema 412 S endocardial electrode (tip material vitreous carbon, tip area 12 mm2) (41 patients) or a Siemens‐Elema 415 S endocardial electrode (tip material platinum, tip area 12 mm2) (38 patients). The groups did not differ in age, sex. magnitude of intracardiac signal or indication for pacemaker treatment. Pacing threshold was measured by the vario technique at 3 and 15 months after the implantation. In the group of carbon‐tip electrodes and in the group of platinum‐tip electrodes stimulation thresholds at implantation were 0.49 ± 0.10 V and 0.54 ± 0.14 V(ns), at months 31.40 ± 0.45 V and 1.57 ± 0.53 V(ns), and at months 15 1.12 ± 0.33 V and 1.37 ± 0.38 V(P = 0.003), respectively. After 1 year, 88% of the patients in the carbon‐tip group and 66% (P ‐ 0.04) in the platinum‐tip group fulfilled our criteria for reducing pacemaker output from 5.0 V to 2.5 V. In comparable platinum‐tip and carbon‐tip pacing electrodes, the chronic stimulation threshold was lower in the carbon‐tip than in the platinum‐tip electrode.
Discrimination of Retrograde from Anterograde Atrial Activation Using Intracardiac Electrogram Waveform Analysis
Authors: THRONE ROBERT D. , JENKINS JANICE M. , WINSTON STUART A. , FINELLI CYNTHIA J. , DICARLO LORENZO A.
Published: July 2006

THRONE, R.D., et al.: Discrimination of Retrograde from Anterograde Atrial Activation Using Intracardiac Electrogram Waveform Analysis The prevention of pacemaker‐mediated tachycardias requires a safe, reliable method for distinguishing retrograde from anterograde atrial activation by dual chamber pacemakers. In this study, a technique was developed to detect the morphological change that occurs in the waveform of the intra‐atrial electrogram during retrograde atrial activation. The method employed for waveform analysis is based upon statistical correlation. In 19 patients undergoing electrophysiological studies, atrial electrograms were recorded from bipolar endocardial electrodes during sinus rhythm and 1:1 retrograde atrial depolarization while undergoing right ventricular pacing. Data were digitally sampled at 750, 1,000, and 1,500 Hz. Templates of anterograde atrial depolarization were constructed by signal averaging waveforms from an initial sinus rhythm passage. These were used for analysis of anterograde depolarizations from a subsequent passage of sinus rhythm and a passage of known retrograde atrial depolarization. In all 19 cases, a patient‐specific threshold could be derived to separate anterograde from retrograde atrial depolarizations using 1,000 Hz and 1,500 Hz sampling rates. However, at a sampling rate of 750 Hz, separation of anterograde from retrograde atrial activation was possible in only 16/19 patients (84%). We conclude that correlation waveform analysis of a suitably sampled atrial electrogram is a reliable method of discriminating retrograde atrial depolarization from anterograde atrial depolarization in intracardiac electrograms.
The Basis for Activity Controlled Rate Variable Cardiac Pacemakers: An Analysis of Mechanical Forces on the Human Body Induced by Exercise and Environment
Authors: ALT ECKHARD , MATULA MARKUS , THERES HEINZ , HEINZ MICHAEL , BAKER ROSS
Published: July 2006

ALT E., et al.: The Basis for Activity Controlled Rate Variable Cardiac Pacemakers: An Analysis of Mechanical Forces on the Human Body Induced by Exercise and Environment We conducted tests on six healthy volunteers and six pacemaker patients. With the aid of three straight line frequency acceleration pickups attached to the body, the mechanical signals were recorded on the three axes during different activities. Along with standardized exercise on bicycle and treadmill ergometers, we tested the influence of household activities and interference influences. The results were analyzed in terms of the amplitude and frequency content of the signals. For walking activities, we found a signal amplitude increasing in a largely linear fashion with the walking speed, the signal amplitudes being approximately twice as high on the vertical axis as on the other two axes. Exercise on the bicycle ergometer produced mechanical signals of clearly lower amplitude than comparable walking activities. The Fast‐Fourier analysis showed amplitude peaks in the low frequency range of 1 to 4 Hz for all forms of physiological exercise, while interference influences showed amplitude peaks mainly in the range above 8 Hz. The use of a straight line‐frequency acceleration pickup and a corresponding low pass filter might be a way of reducing the effect of unphysiological interference influences on an activity controlled pacemaker system. A sensor measuring on the horizontal axis appears to be the most favorable compromise for the various types of exercise. However, due to the considerable difference in signal amplitude for different types of exercise of the same intensity, an activity controlled pacemaker system cannot entirely meet metabolic conditions and requirements.
Localization of Accessory Pathways in the Wolff‐Parkinson‐White Syndrome
Authors: SZABO TIBOR S. , KLEIN GEORGE J. , GUIRAUDON GERARD M. , YEE RAYMOND , SHARMA ARJUN D.
Published: July 2006

SZABO, T.S., et al.: Localization of Accessory Pathways in the Wolff‐Parkinson‐White Syndrome Operative and ablative therapy in the Wolff‐Parkinson‐White syndrome requires accurate localization of accessory atrioventricular pathways. A reasonable first approximation to pathway location can be obtained by noninvasive techniques, the 12‐lead electrocardiogram being the most readily available of these. Accurate characterization of the number and anatomic localization of accessory pathways still requires invasive electrophysiological assessment. The most useful technique for accessory pathway localization remains endocardial atrial mapping of the tricuspid and mitral (via the coronary sinus) ring during atrioventricular reciprocating tachycardia and ventricular pacing. Other techniques provide important confirmatory evidence and may be the only guides to accessory pathway location in selected individuals.
Upper Limit Ventricular Stimulation in Respiratory Rate Responsive Pacing due to Electrocautery
Authors: VAN HEMEL NORBERT M. , HAMERLIJNCK RUBEN P.H.M. , PRONK KEES J. , VAN DER VEEN ED P.
Published: July 2006

VAN HEMEL, N.M., et al.: Upper Limit Ventricular Stimulation in Respiratory Rate Responsive Pacing due to Electrocautery Transient programmed upper limit stimulation (150 bpm) was observed during repetitively utilized electrocautery in the beginning of an open‐heart surgical procedure in a patient with a minute ventilation rate responsive ventricuiar pacemaker. This tachycardia caused severe hemodynamic deterioration, and was also initiated by internal heart massage and manual ventilation. Considering the recommendations of the manufacturer, this series of serious events could have been prevented, when reprogramming to the inhibited mode had been executed in anticipation of the operation.
Use of the Elective Replacement Indicator in Predicting Time of Automatic Implantable Cardioverter‐Defibrillator Battery Depletion
Authors: AARONS DIANA , MOWER MORTON , VELTRI ENRICO
Published: July 2006

AARONS, D., et al.: Use of the Elective Replacement Indicator in Predicting Time of Automatic Implantable Cardioverter‐Defibrillator Battery Depletion The elective replacement indicator (ERI) of an automatic impiantable cardioverter‐defibrillator (AICD) is intended to be utilized as strict criteria for the appropriate timing of pulse generator replacement. The manufacturer's newest recommendations suggest replacement within 3 months post‐KRI attainment and this applies to both AID‐B units and the latest Ventak models currently being implanted with expectations for increased battery longevity. Twelve patients with the AID‐B model were prospectively evaluated in regard to (a) time from attainment of ERI to generator exchange and (b] total battery life with respect to the presence or absence of spontaneous discharges. In the overall group, the ERI was reached at 18.9 ± 3.9 months (mean + standard deviation). The time from ERI attainment to generator exchange due to battery depletion was 8.1 ±5.1 months, and total battery life was 27.3 ± 3.1 months. In the group with sponlaneous discharges, the duration of time (months) post‐ERI to generator exchange was 5.7 ± 2.6 but was 11.4 ± 6.1 in the others (P = 0.052); battery life was 25.7 ± 2.4 and 29.4 ± 2.7, respectively (P = 0.03). We conclude that the current ERI recommendation seems overly conservative in planning generator exchange for patients without the occurrence of spontaneous discharges and appropriate for patients with such discharges.
Undersensing of P Waves in the Presence of an Adequate P Wave Due to Automatic Postventricular Atrial Refractory Period Extension
Authors: WILSON JOHN H. , LATTNER STEPHEN
Published: July 2006

WILSON, J.H., et al.: Undersensing of P Waves in the Presence of an Adequate P Wave Due to Automatic Postventricular Atrial Refractory Period Extension Two cases in which a DDD pacemaker failed to track P waves due to repetitive activation of the automatic postventricular atrial refractory period (PVARP) extension are reported. In one case, the cycle was initiated by a premature ventricular contraction (PVC); in the other, by touching the unipolar pacemaker with a needle while suturing. We demonstrated that chest wall stimulation can be used to induce cycles of repetitive automatic PVARP extension and failure to track P waves. We demonstrated in vitro that touching a unipolar pacemaker with a needle can generate a signal suffiicient to mimic a QRS complex, and initiate a cycle of repetitive P wave undersensing.
Influence of Pacing Mode and Rate on Peripheral Levels of Atrial Natriuretic Peptide (ANP)
Authors: NOLL B. , KRAPPE J. , GÖKE B. , MAISCH B.
Published: July 2006

NOLL, B., et al.: Influence of Pacing Mode and Rate on Peripheral Levels of Atrial Natriuretic Peptide (ANP The effect of acute modifications of pacing mode and rate on plasma ANP levels was evaluated. ANP was determined in ten resting patients with ODD pacemokers due to binodal disease or intermittent second‐ and third‐degree AV block. At 82/minute pacing rate the ANP plasma levels (normal range 2 to 30 fmol/mL) corresponded to those under AAI (4.05 ± 2.10 fmol/mL) and DDD (4.18 ± 2.02 fmol/mL) pacing, but increased significantly (P < 0.05) during VVI pacing (6.96 ± 3.70 fmol/mL). Acceleration of DDD stimulation frequency from 82 to 113/minutes led to significant increases of ANP levels by the factor of three in all chosen AV delays. The lowest ANP plasma levels were measured of 175 msec AV delay under 82/minute pacing rate in DDD mode. Under 113/minutes the differences of ANP concentration after variations of AV delays were less pronounced. The influences of altered atrial pressure and tension on ANP release are discussed to account for changes in ANP plasma levels following different modes and rates of pacemaker stimulation.
Modulated Parasystole Complicating Permanent Ventricular Pacing: The Different Influence of Spontaneous and Paced Impulses Upon the Parasystolic Rhythm
Authors: ORETO GIUSEPPE , DONATO ANTONINO , PATANÉ SANTINA , SATULLO GAETANO , LUZZA FRANGESGO , BRAMANTI ORESTE
Published: July 2006

ORETO, G., et al.: Modulated Parasystole Complicating Permanent Ventricular Pacing: The Different Influence of Spontaneous and Paced Impulses Upon the Parasystolic Rhythm A case of modulated ventricular parasystole observed in a patient with a VVIM pacemaker is reported. Analysis reveals that the electrotonic influence (modulation) effected upon the parasysiolic focus hy the sinus impulses is different from that exerted by the paced impulses. Furthermore, fusion beats reflect an intermediate modulating effect according to the prevalence of the sinus or the paced wavefront.
Summation and Inhibition by Ultrarapid Train Pulses in Dogs: Effects of Frequency and Duration of Trains, Lidocaine, and Beta Blockade
Authors: INOUE HIROSHI , SAIHARA SHINICHIRO , TODA IKU , SUGIMOTO TSUNEAKI
Published: July 2006

INOUE, H., et al.: Summation and Inhibition by Ultrarapid Train Pulses in Dogs: Effects of Frequency and Duration of Trains, Lidocaine, and Beta Blockade To test whether summation and inhibition of excitation hy uitrarapid train pulses were modified by frequency and duration of trains, using lidocaine and beta blockade, the strength‐interval relationship was determined with a single extrastimulus and train pulses (100 and 200 Hz) in 28 anesthetized, open‐chest dogs. The effective refractory period (ERP) determined at 5 mA was shorter for trains than for single stimulus (summation). Summation determined at 15 mA increased progressively as the duiation of trains was increased to 50 msec after which it reached a plateau. ERP determined at 2 mA was longer with train pulses than with single stimulus (inhibition). Inhibition for 200 Hz trains increased linearly with train duration up to 200 msec, while for 100 Hz trains it became constant when the duration was 80 msec. Lidocaine fplasma concentration; 2.6 ± 1.0 μg/mL) did not affect inhibition and summation in 11 dogs. Propranolol (1 mg/kg, iv) increased summation at 15 mA (n = 7,30 ± 10 vs 46 ± 11 msec with 100 Hz trains, P < 0.01), but did not afect inhibition (37 ± 26 vs 29 ± 17 msec, NS). In conclusion, (1) effect of frequency of train pulses was more on inhibition than on summation; (2) lidocaine did not affect inhibition and summation; and (3) propranolol increased summation but not inhibition.