bluuebunny/crossref_metadata_2025 huggingface dataset:
Defibrillation with Low Voltage using a Left Ventricular Catheter and Four Cutaneous Patch Electrodes in Dogs
Authors: GUE PAUL A. , KAVANAGH KATHERINE M. , ALFERNESS CLIF A. , WOLF PATRICK D. , ROLLINS DENNIS , HAGLER JENNY , SMITH WILLIAM M. , IDEKER RAYMOND E.
Published: July 2006

The purpose of this study was to determine a lower limit of defibrillation thresholds (DFTs) that could be used to evaluate nonthoracolomy lead configurations for implabtable defibrillators. A lead configuration that consisted of a left ventricular catheter and four cimcumferential cutaneous patches was tested because it was hypothesized to create a relatively uniform electric field for defibrillation. In eight anesthetized dogs, three 8F defibrillaling catheters with 6 cm platinum clad titanium tips were inserted into the right ventricle (R), right ventricular outflow tract (O), and left ventricle (1). Four cutaneous patch electrodes (4P), each with a surface area of 42 cm2, were placed on the left lateral, right lateral, anterior and posterior thorax. DFTs for ten lead configurations, consisting of different combinations of these electrodes, were evaluated. DFTs were determined by using a modified Purdue technique and applying a single capacitor biphasic shock with both phases 6 ms in duration after 15 sec of electrically induced fibrillation The L−→4P+ configuration produced a lower DFT than R−→4P+ (3.2 ± 1.6 J vs 8.0 ± 4.2 J, P < 0.001) with reduced current (2.6 ± 0.7 A vs 4.1 ± 1.2 A, P < 0.001). Lowering the impedance by a mean of 40%, configurations that used four patches produced lower DFTs than those that used a single left lateral patch. The use of an O catheter produced lower DFTs only when used in conjunction with an R catheter. Of the ten configurations tested, L−→4P+ produced the lowest DFT for two possible reasons; (1) it produced a more uniform distribution of current density throughout the ventricular mass, and (2) the large surface area of the cutaneous electrodes decreased the impedance. While this configuration may not be useful clinically, it approximates a minimum DFT that can be used to judge the efficacy of more practical lead configurations.
Effects of Stress and Beta1 Blockade on the Ventricular Depolarization Gradient of the Rate Modulating Pacemaker
Authors: SINGER IGOR , BRENNAN A. FRANCES , STEINHAUS BRUCE , MALDONADO CLAUDIO , KUPERSMITH JOEL
Published: July 2006

Prism‐CLR is a dosed loop, rate modulating pacemaker that uses ventricular depolarization gradient (Gd) to continuously adjust heart rate. Heart rate response to a formal mental stress protocol, esmolol (500meg/kg bolus, 75–125 mcg/kg/min infusion), and mental stress during esmolol infusion were studied in six patients to investigate if Gd and paced heart rate response are under direct beta‐adrenergic control. Paced heart rates increased in response to mental stress in a physiological manner (P < 0.001). Response to esmolol infusion was paradoxical, with increased paced heart rates during esmolol bolus and infusion (P < 0.05). There was no significant alteration in either systolic or diastolic blood pressure during mental stress or esmolol infusion (P > 0.05). Paradoxical increase in paced heart rates during esmolol administration suggests a primary or secondary effect of esmolol to decrease the ventricular depolarization gradient, This hypothesis was supported in four dog studies in which direct Gd measurements were made during esmolol infusion. Mental stress during esmolol infusion resulted in significantly increased paced heart rates (esmolol effect) with blunted changes in heart rate in response to the mental stress. The results of this study suggest that the physiological rate response during mental stress is attributable to sympathetic autonomic response.
Autologous Skeletal Muscle, an Alternative for Cardiac Assistance
Authors: RUGGIERO RENATO , POCHETTINO ALBERTO , HAMMOND ROBERT L. , AMI HIROSHI NUN , HUIPING LU , SPANTA ALI D. , STEPHENSON LARRY W.
Published: July 2006

Original attempts to use skeletal muscle for cardiac assistance were soon abandoned when the problem of muscle fatigue could not be solved. In the last 2 decades, better understanding of muscle physiology and the development of successful protocols of electrical muscle conditioning have given new impetus to researchers around the world to proceed in the effort to identify useful applications of skeletal muscle to support the heart. More than 100 patients around the world have undergone cardiomyoplasty, mostly for cardiac failure. While subjective improvement in symptoms was noticed in the majority of the patients, only recently favorable hemodynamic changes have been documented. The other alternative that has been pursued in the laboratory is the construction of skeletal muscle ventricles that, after conditioning and vascular delay, have been shown to provide significant cardiac support when used for diastolic counterpulsation or for right heart bypass in animal models.
The Effect of Posture on the Response to Atrioventricular Synchronous Pacing in Patients with Underlying Cardiovascular Disease
Authors: HOESCHEN ROBERT J. , REIMOLD SHARON C. , LEE RICHARD T. , PLAPPERT THEODORE J. , LAMAS GERVASIO A.
Published: July 2006

In order to determine whether the hemodynamic benefit of atrioventricular synchronous pacing is maintained in the upright position, 14 patients with dual chamber pacemakers were paced in VVI mode and DDD mode in both the supine and standing position. The hemodynamic response was assessed by measuring the velocity time integral derived from the pulsed‐wave Doppler signal in the left ventricular outflow tract during VVI pacing and dual chamber pacing at three different AV delays (125, 200, 250 ms). In the supine position, the velocity time integral during VVI pacing was 14.6 ± 3.0 cm and this increased during DDD pacing at all three AV delays (17.7 ± 3.3, 17.9 ± 3,0, 17.5 ± 3.5 cm). In the upright position, the velocity time integral during VVI pacing was 12.9 ± 3.5 cm and this increased with DDD pacing (15.5 ± 3.3, 15. 1 ± 4.0, 15.1 ± 3.9 cm). It was concluded that although stroke volume decreases when assuming the upright position, the beneficial response to dual chamber pacing is maintained and equals that observed in the supine position.
Ventricular Pacing Threshold and Time to Capture Postdefibrillation in Patients Undergoing Implantable Cardioverter‐Defibrillator Implantation
Authors: KHASTGIR TERRANCE , LATTUCA JOHN , AARONS DIANA , MURPHY JOSEPH , O'MARA VICKI , JUANTEGUY JUAN , VELTRI ENRICO P.
Published: July 2006

To assess the effect of defibrillation and amiodarone on ventricular pacing threshold and time to capture in patients undergoing automatic implantable cardioverter‐defibrillator (AICD) implantation, 28 patients were prospectively evaluated. The patients were entered into one of two protocols: la—epicardial ventricular pacing threshold measured at baseline (preventricular fibrillation induction) and 10 and 60 seconds postdefibrillation with 20 J, or Ib—two fibrillation‐defibrillation sequences were performed 3 minutes apart and ventricular pacing thresholds were measured for each sequence at baseline and at 10 and 60 seconds postdefibrillation with 20 J. Ten patients also underwent asynchronous pacing at 1.1 times baseline threshold during ventricular fibrillation with measurement of time to capture postdefibrillation. All patients were randomly assigned to receive either amiodarone or no antiarrhythmic drug therapy. Ventricular fibrillation was induced with AC (applied for 1‐2 seconds), and standard epicardial bipolar and epicardial patch electrodes of the AICD were used for pacing and defibrillation, respectively. Ventricular pacing threshold at baseline, 10 seconds, 60 seconds, and 3 minutes postdefibrillation did not differ significantly. There were no significant differences in patients with or without amiodarone therapy. Furthermore, there was no transient loss of ventricular capture postdefibrillation or significant difference in time to capture with amiodarone (≤ 2 seconds). We conclude that following internal defibrillation with 20 J: (1) ventricular pacing threshold at 10 seconds, 60 seconds, and 3 minutes were not significantly different from baseline with one or two fibrillation‐defibrillation sequences, (2) time to capture was short, and (3) there was no significant difference in no drug versus amiodarone. These findings have direct clinical importance in considering device therapy with both pacing and defibrillating capabilities.
Day Case Permanent Pacing
Authors: HAYWOOD GUY A. , JONES SUE M. , CAMM A. JOHN , WARD DAVID E.
Published: July 2006

We have previously reported our preliminary experience of day‐case permanent pacing in the United Kingdom. The study has now been extended to 50 patients with follow‐up of 22 ± 4 months. During the study period, all patients referred for permanent pacing, either to the senior author, or as in‐hospital transfers, were considered for the study. Forty two percent of patients considered fulfilled inclusion and exclusion criteria, resulting in a total of 50 patients being randomized either to day case or conventional in‐patient management. In the first month postimplantation, one patient in each group developed a complication requiring revision of system. Only one further pacing related complication occurred over the follow‐up period, percutaneous extrusion of a fixation sleeve with spontaneously healing of the wound. This was in a day‐case patient. Mean duration of in‐patient stay was 5.7 hours in day‐case patients, compared with 70.0 hours in those managed conventionally. Postimplantation local physician consultation rates were equal in both groups. Questionnaires were used to determine the relative acceptability to patients of the two management protocols; on a ten point score of acceptability, the mean score for both groups was 8.8. The difference in cost per patient using day‐case management was approximately £430 ($817). We conclude that day‐case permanent pacing in the United Kingdom is feasible, acceptable to patients, and has considerable economic benefits.
What is the Ideal Pulse Frequency for Skeletal Muscle Stimulation After Cardiomyoplasty?
Authors: LUCAS CAROLINE M.H.B. , VAN DER VEEN FREDERIK H. , GRANDJEAN PIERRE A. , PENN OLAF C.K.M. , WELLENS HEIN J.J.
Published: July 2006

Routinely the latissimus dorsi (LD) muscle is stimulated with bursts of pulses at 30 pulses/sec after Cardiomyoplasty to assist the failing heart. At a lower pulse frequency the contractile force decreases and at higher frequencies the energy demand of the pacemaker increases rapidly. We investigated the effect of the stimulus frequency variation on contractile force in untrained LD muscles and in muscles after 12 weeks of continuous cyclic electrical stimulation. In six dogs, two electrodes (Medtronic SP5528) were implanted in the left LD muscle together with an ltrel muscle stimulator. The LD muscle was stimulated with 30 pulses/sec in bursts to deliver initially 30 and after 10 weeks 80 contractions per minute. Both before and after training of the LD muscle maximum force was observed by stimulating with a frequency of 36 to 130 pulses/sec in a burst. However, training induced a shift in the steep part of the force‐frequency relation to lower frequencies. In particular, at 15 pulses/sec 60% of the maximal force was obtained in contrast to 40% before training. A fatigue test of 8 minutes duration was performed specified by 100 bursts/min and a burst duration of 0.25 sec at pulse frequencies of 30, 36, 50, and 85 pulses/sec. The contractile force decreased significantly during the course of the test at all frequencies. However, the force obtained with 30 pulses/sec stimulation was lower during the initial phase and approximately 10% higher at the end of the fatique test as compared to 36, 50, and 85 pulses/ sec stimulation. We conclude that when the LD muscle is demanded to assist afailing heart by contracting 100 times a minute, pulse trains with a frequency of 30 pulses/sec deliver a near maximal contractile force (80%) and are significantly less fatiguing in comparison to pulse (rains at higher frequencies. This indicates that LD muscle stimulation after Cardiomyoplasty should be performed at 30 pulses/sec.
Assessment of Effects of a Radiofrequency Energy Field and Thermistor Location in an Electrode Catheter on the Accuracy of Temperature Measurement
Authors: BLOUIN LEONARD T. , MARCUS FRANK I. , LAMPE LOUIS
Published: July 2006

Accurate measurement of temperature at the interface of the delivery electrode and the tissue during transcatheter delivery of radiofrequency energy (RFE) for ablation would provide better control of lesion production. Electromagnetic energy fields can affect the accuracy of temperature measurement with thermistors. An electrode probe was fabricated with a thermistor and an optical sensor in the center of the delivery electrode. Simultaneous temperature measurements during RFE delivery to cardiac tissue in the 37°C bath showed good agreement between the sensors, indicating that the RFE field did not cause errors in thermistor temperature measurements with the electrode probe used. A second electrode probe was designed to determine optimal thermistor location. It was constructed using two thermistors with identical temperature‐resistance curves. One thermistor protruded through a hole in the side of the delivery electrode and was thermally isolated from it. The other thermistor was bonded to the inner surface of the electrode with heat conductive epoxy. The electrode was placed in contact with cardiac tissue in a 37°C bath of flowing saline with the protruding thermistor centered in the area to be heated. Temperatures measured at steady state during RFE delivery with the protruding thermistor were consistently higher than those of the inner wall thermistor, ranging from 1.8°C difference at 46°C to 8.3°C difference at 75°C interface temperature. The thermistor must be in contact with the tissue and thermally isolated from the delivery electrode for accurate determination of electrode/tissue interface temperature.
Determinants of Subsidiary Ventricular Pacemaker Suppression in Man
Authors: SCHMIDINGER HERWIG , PROBST PETER , SCHNEIDER BARBARA , WEBER HEINZ , KALIMAN JOSEF
Published: July 2006

To investigate the relative contribution of the duration and rate of overdrive to subsidiary ventricular pacemaker suppression, in six patients with complete heart block after His‐bundle ablation, ventricular overdrive stimulation studies were performed. The studies, which were spread over a mean follow‐up period of 745 days, were carried out invasively with a temporary lead (one patient) as well as nonin‐vasively with the implanted pacemakers and chest wall inhibition (five patients). The overdrive pacing rate was increased in steps of 10 beats/min, and the pacing duration was 15, 30, 60, 90, and 120 seconds at each level. A recovery period of 2 minutes was allowed after each overdrive stimulation. Incremental ventricular overdrive stimulation at increasing pacing durations consistently caused progressive suppression of ventricular impulse formation. Nonparamelric variance analysis demonstrated a significant (P < 0.0001) influence of both the pacing rate and duration on ventricular recovery time. Nonlinear regression showed an exponential increase in recovery time with incremental pacing rate and a biphasic increase in recovery time with incremental pacing duration. Beyond a pacing duration of 60 seconds ventricular impulse suppression was primarily dependent upon the pacing rate. A nonlinear regression model was applied to predict the number of heals required for return of the escape rhythm toward prepacing control values. The predicted maximum mean number of beats was 15.4 ± 5.9 and independent of the rate and duration of pacing, although, the initial temporary instability of the escape rhythm was directly related to the degree of overdrive.
Effects of Atrial Impulse Timing on AV Concealed Conduction in the Rabbit Heart
Authors: CHORRO FRANCISCO J. , SANCHIS JUAN , LOPEZ‐MERINO VICENTE , SUCH LUIS , AVELLANA JUAN A. , VALENTIN VICENTE
Published: July 2006

The influence of the timing of a nontrunsmitted or transmitted atrial impulse on the atrioventricular (AV) conduction time of the subsequent impulse was studied in nine isolated rabbit hearts. AV conduction curves were determined by applying the atrial extrasfimulus test. The extrasfimulus was delivered preceded or not by an interposed afrial impulse whose coupling interval with respect to the last atria] beat of a basic train was kept constant at 100, 120, 140, 160, 175, 200, 225, 250, and,300 msec. In all experiments, there was a “concealment interval,” i.e., the AV effective refractory period was longer than the atrial functional refractory period, and in seven experiments was comprised between 100 and 160 msec. For any given extrastunulus coupling interval in the presence of an interposed nontransmitted atrial impulse, AV conduction time was significantly greater than in its absence; the increase was greater than the longer the nontransmifted atrial impulse coupling interval, i.e., the shorter the subsequent transmitted impulse coupling interval with respect to the previous interposed nontransmitted impulse. The AV conduction curves relating the extrastimulus AV conduction time to its coupling interval with respect to the last atrial impulse of the basic train fitted to a hyperbolic model both in the absence of the interposed atrial impulse and in its presence (mean square residual 31 ± 23 msec2). and the interposed atrial impulse modified the constants of the functions; the slope of the linear transformations was progressively more negative as the interposed atrial impulse was delayed. Furthermore, the effects of the interposed atrial impulse—transmitted or not—on AV conduction time of the subsequent impulse were qualitatively similar, their magnitude depending on the time elapsed between the two.
The Surgical Aspects of Automatic Implantable Cardioverter‐Defibrillator Implantation
Authors: WATKINS LEVI , TAYLOR ERIC
Published: July 2006

Since February 1980, the automatic implantable ccirdioverter‐defibrillator (AICD) has been implanted in over 12,000 patients. This report examines the surgical aspects of AICD implantation. The various surgical techniques, their indications, and our recent clinical experience in over 250 patients are reviewed
Implantable Cardioverter Defibrillator: Possible Hazards of Electromagnetic Interference
Authors: SCHMITT GLAUS , BRACHMANN JOHANNES , WALDECKER BERND , NAVARRETE LILIA , BEYER THORSTEN , PFEIFER ANNEROSE , KUBLER WOLFGANG
Published: July 2006

We report on three patients with an automatic, implantable Cardioverter defibrillator (AICD, CPI) in whom the device had been deactivated due to electromagnetic interference. In all cases, the source of the electromagnetic disturbances could be identified.
Asymptomatic Left Ventricular Malposition of a Transvenous Pacemaker Lead Through a Sinus Venosus Defect: Follow‐up Over 17 Years
Authors: VAN ERCKELENS FRANZ , SIGMUND MARTIN , LAMBERTZ HEINZ , KREIS ANDREAS , REUPCKE CHARLOTTE , HANRATH PETER
Published: July 2006

The case of a woman with an asymptomatic transvenous left ventricular endocardial pacemaker lead is presented. The chest X ray and the electrocardiogram suggested pacemaker catheter malposition. By two‐dimensional echocardiography, the pacemaker lead was shown to cross from the left atrium through the mitral valve and implant in the left ventricular endocardium. The underlying sinus venosus defect and the passage of the electrode through this interatrial communication were directly visualized by transesophageal echocardiography, No thrombotic material attached to the lead was detected corresponding to the patient's uneventful course for surprisingly more than 17 years without evidence of past or present neurological deficiencies or of peripheral embolic phenomena. Thus, no operative correction was performed. Warfarin sodium therapy, however, was initiated.
Syncope Secondary to Paroxysmal High Grade AV Block in a Heavily Trained Man
Authors: HURWITZ JODIE L. , CONLEY MARTIN J. , WHARTON J. MARCUS , PRYSTOWSKY ERIC N.
Published: July 2006

J.B. is a well‐trained male with syncope due to paroxysmal AV nodal heart block who ultimately required a permanent pacemaker despite an initial attempt at cessation of training only. Baseline sinus node function was normal, but AV nodal conduction remained abnormal even after autonomic blockade supporting intrinsic AV nodal dysfunction. This case illustrates that vigorous physical training may unmask previously unrecognized intrinsic dysfunction of AV nodal conduction or, as previously reported for physical training induced sinus node dysfunction, cause AV nodal dysfunction. Simple cessation of training to treat this problem is often recommended but may not be adequate for some patients who remain at risk for recurrent syncope during the deconditioning period.
Diastolic Potentials Recorded by Surface Electrocardiographic Signal Averaging During Sustained Ventricular Tachycardia: Possible Origin From the Reentrant Circuit
Authors: KREMERS MARK S. , HSIA HENRY , WELLS PETER , BLACK WILLIAM , SOLO MARTHA , ALBERT DAVID
Published: July 2006

ECG signal averaging can detect low amplitude diastolic potentials in sinus rhythm. We, therefore, recorded signal‐averaged ECGs during eight episodes of inducible uniform sustained VT with coincident atrial pacing to look for continuous diastolic electrical activity. Simultaneous AV pacing in seven patients served as controls. The number of QRS complexes averaged (187 ± 47 vs 183 ± 63), the noise level (1.26 ± 0,88 vs 1.39 ± 0.47) and cycle length (385 ± 52 vs 404 ± 40) did not differ between VT and paced recordings. In each lead the difference in onset between the unfiltered surface recording and the filtered data (40 Hz bidirectional) was significantly greater in VT than the paced recordings (25 ± 16 vs 11 ± 8 msec, P = 0.0012), These late diastolic (pre‐QRS) potentials were > 15 msec duration in 65% of the leads in VT versus 20% of paced recording (P = 0.021). The maximum value was > 20 msec in six VT (75%) versus one (14%) paced recording (P = 0.019), The earliest filtered onset in any lead preceeded the earliest surface activity by > 12 msec, in 6 VT versus one paced recording (P = 0.019). Early diastolic (post‐QRS) potentials were also longer in VT than pacing (49 ± 40 versus 5 ± 20. P = 0.001) and exceeded 38 msec in seven of the VTs but none of the paced recordings (P ‐ 0.001). While no VT recording showed continuous activity, total electrical activation was longer in VT than pacing (282 ± 49 versus 210 ± 39, P = 0.0079) and constituted 73%± 9% of the VT cycle versus 52%± 8% of the paced cycle (P = 0.0004). We conclude that both early and late diastolic potentials can be demonstrated in inducible sustained uniform VT by signal averaging. These potentials might arise from the reentrant pathway and constitute a marker for ventricular reentry.
The Interaction of Antiarrhythmic Drugs and the Energy for Cardioversion of Chronic Atrial Fibrillation
Authors: GUARNIERI THOMAS , TOMASELLI GORDON , GRIFFITH LAWRENCE S.C. , BRINKER JEFFREY
Published: July 2006

Antiarrhythmic drugs may alter the energy for Cardioversion of ventricular arrhythmias. This study compares the energy necessary for cardioverting chronic atrial fibrillation in 57 patients taking type Ia, Ic, or type III antiarrhythmic drugs. Patients taking Ia (n = 22) or III (n = 14) drugs had a median energy for Cardioversion of 100 joules, while the patients taking Ic (n = 17) drugs had a median energy of 200 joules (P = 0.03). There were no differences in the frequency of unsuccessful Cardioversion, There were no serious adverse events in any of the three groups, although three patients in the Ic group had > 3 second pauses after the shock. The data suggest that the use of Ic antiarrhythmic drugs results in a higher energy for cardioversion of atrial fibrillation. However with higher energies, conversion is as successful as for type Ia and type III.
The Pulmonary Artery Lasso: Epicardial Pacing Lead Causing Right Ventricular Outflow Obstruction
Authors: PERRY JAMES C. , NIHILL MICHAEL R. , LUDOMIRSKY ACHI , OTT DAVID A. , GARSON ARTHUR
Published: July 2006

Permanent pacing in small children may require placement of an epicardial pacing system. This report describes a young child who underwent pacemaker implantation with epicardial ventricular lead placement in infancy as an adjunct to antiarrhythmic therapy for congenital functional ectopic tachycardia. At 5 years of age, a harsh systolic murmur was detected for the first time. Evaluation by catheterization and Iransluminal echocardiography showed right ventricular outflow obstruction (pressure gradient 40 mmHg) secondary to extrinsic compression by the epicardial lead. Surgical removal of the lead relieved the obstruction.
Wenckebach Periods in Sinoatrial Block: Experimental and Clinical Evidence
Authors: LE HEUZEY JEAN‐YVES , CARON JACQUES , GUIZE LOUIS , LIBERSA CHRISTIAN , KACET SALEM , BOUTJDIR MOHAMED , LAVERGNE THOMAS , LEKIEFFRE JEAN
Published: July 2006

The reality of sinoatrial Wenckebach periods (WP) has been suggested, but not proven, in the literature. We report experimental and clinical data showing WP in sinoatrial blocks. Experimental sinoatrial blocks were induced by superfusion of bepridil (10 ‐5 M) in 15 preparations of isolated rabbit right atria. Different types of block were observed, including Blumberger I block, i.e., sinoatrial WP. The recordings showed that the typical pattern of Blumberger type IA block and sinoatrial WP may be due to transient acceleration of the sinus rate, without change in the increment. We also observed sinoatrial WP in a 72‐year‐old patient on direct recordings of the sinus node (SN) electrical activity. In this case, transient acceleration of the sinus rate also seemed to be involved in the genesis of sinoatrial WP. Analysis of these clinical and experimental data showed similarities that may explain the mechanism of the WP. Usually type 1A Blumberger block is said to involve a decrease in the sinoatrial increment to explain the atrial sequence (decrease in PP interval followed by a pause shorter than twice the value of the preceding cycle, then a cycle longer than the one preceding the pause). In fact, this pattern can be observed when the acceleration of the higher structure, the SN, induces block within the lower structure, i.e., the atrium.
Amplitude and Direction of Atrial Depolarization Using a Multipolar Floating Catheter: Principles for a Single Lead VDD Pacing
Authors: FLAMMANG DANIEL , RENIRIE LEX , BEGEMANN MALCOLM , VAN KRIEKEN FRITS
Published: July 2006

VDD stimulation using a single catheter for atrial sensing and ventricular sensing and pacing has become a reality. In order to compare the quality of the cavitary atrial electrogram (AEG) and to determine the intracitrial P wave direction and conduction time (CT), we compared, in an acute study, three different types of atrial electrode systems using four different leads, in 53 patients in sinus rhythm. The three electrode systems were: (1) one experimental system with quodripolar orthogonal electrodes using the Goldreyer concept; (2) one experimental system with quadripolar whole ring electrodes; (3) two systems with diagonally oriented half‐ring electrodes, one experimental quadripolar and one bipolar CCS commercial (Polysafe A‐Track lead). For the experimental systems, the four electrodes forming two independent bipolar pairs were situated on the intra atrial floating portion of a single lead and one supplemental electrode was distally positioned in the right ventricular apex. Bipolar AEGs were recorded at the high and at the low levels of the right atrium. For the CCS lead, the single bipolar AEG was recorded at the high level of the right atrium only. The highest AEG amplitude and the highest values for ventricular far‐field rejection were provided by both diagonally oriented half‐ring electrodes at the high atrial level and by the whole ring electrodes at the low atrial level. For both atrial levels, the orthogonal electrode system provided the smallest AEG amplitudes, the highest ventricular electrogram amplitudes, and therefore, the smallest values for ventricular far‐field rejection. With the three quadripolar experimental systems, in sinus rhythm, the direction of the intraatrial depolarization was high‐low in 46 patients (87%) and low‐high in 3 patients (6%), with a mean CT of 28.9 ms and 23.3 ms, respectively; high and low AEGs were recorded simultaneously in 4 patients (7%). During ventricular pacing, retrograde (V‐A) conduction was present in 35 patients. The intraatriai depolarization was low‐high in 25 of them (71%) and high‐low in 7 patients (20%), with a mean CT of 32.6 ms and 23,4 ms, respectively; high and low AEGs were recorded simultaneously in 3 patients (9%), but with different morphology and polarity than in sinus rhythm. In conclusion, the floating multipolar whole ring and half‐ring electrodes are capable of recording high quality AEG and, because of their multipolarity, they are capable of providing information about atrial activation sequences. These features may theoretically be useful for a monolead VDD pacing system with diagnostic features.
Successful Catheter Ablation of Human Ventricular Tachycardia with Radiofrequency Current Guided by an Endocardial Map of the Area of Slow Conduction
Authors: KUCK KARL‐HEINZ , SCHLÜTER MICHAEL , GEIGER MANFRED , SIEBELS JÜRGEN
Published: July 2006

A case is presented of a 68‐year‐old male patient with a history of myocardial infarction and recurrent ventricular tachycardia who was successfully treated with a single 20‐second transcatheter application of radiofrequency current. Prior to current application a complete endocardial map had been obtained of an area of slow conduction that extended caudo‐cranially for approximately 2 cm along the lower left ventricular septum. Stimulation techniques yielded evidence that this area was critically related to tachycardia initiation and maintenance. Its central part was subsequently chosen as the site for current delivery.
Therapeutic Irradiation over a Permanent Cardiac Pacemaker
Authors: TESKEY R.J. , WHELAN I. , AKYUREKLI Y. , EAPEN L. , GREEN M.S.
Published: July 2006

Therapeutic irradiation of fields containing cardiac pacemakers presents a unique problem to pacemaker physicians and radiation oncologists alike. The present case involved a proposed radiation field containing both subclavian pockets. As an alternative solution, the Cordis model 334A implantable pulse generator was irradiated using a backup temporary pacemaker that was kept outside of any significant radiation exposure. A total of 60 Gy was delivered in 30 fractions, with backup temporary pacing and continuous ECG monitoring used for the first 5 fractions. Frequent re‐evaluation of pacing and sensing function revealed no changes as a result of irradiation; following radiotherapy, transtelephonic monitoring showed normal pacemaker function for a 4 month follow‐up. This represents a useful alternative, particularly for nonmultiprogrammable pacemakers that are made of more radiation‐resistant technology.
Resolution of High Initial Epicardial Patch Defibrillation Thresholds Following Chronic Implantation
Authors: GRUBB BLAIR P. , MANCINI MARY , TEMESY‐ARMOS PETER , HAHN HARRY , ELLIOTT LAURA
Published: July 2006

To determine what effect chronic implantation of automatic implantable car‐dioverter defibrillator epicardial patch electrodes had on initial high defibrillation thresholds at implant, six patients were studied. There were five men, one woman, mean age 61 years. Three had coronary artery disease and three had dilated cardiomyopathies. Mean ejection fraction was 20%. Two patients underwent concomitant coronary artery revascularization and one underwent mitral valve replacement. No patient was on antiarrhythmic drugs. At the time of initial implant, adequate defibrillating thresholds could not be obtained in any patch configuration despite the use of up to 40 joules. Further testing was precluded in each patient due to the development of profound hypotension ( 70 mmHg systolic) that was poorly responsive to pressors. The patch electrodes were then implanted in an arbitrary anterior‐posterior position and the leads were tunneled to an abdominal pocket. After 10–15 days (mean 11), the lead ends were exposed and defibrillation testing was performed again. In all six patients, adequate defibrillation thresholds were obtained (mean 18 joules). We conclude that if adequate defibrillation thresholds cannot be obtained at implant and if further testing cannot be performed without jeopardizing the life of the patient, the patch electrodes should be implanted and retesting performed at 10–15 days.
Pacemaker Infection with Mycobacterium Avium Complex
Authors: AMIN MAHESH , GROSS JAY , ANDREWS CAROLYN , FURMAN SEYMOUR
Published: July 2006

A 21 ‐year‐old, HIV negative, malnourished, homeless woman with congenital heart block had a pacemaker implanted at 7 years of age and multiple procedures thereafter. The most recent of these procedures was replacement of a pulse generator in the right pectoral region. Four months later she had fever, pain, and swelling over the implant site resulting from infection with mixed flora and Mycobacterium avium complex. The pacemaker system was removed fay thoracotomy via a median sternotomy and a new DDD pacemaker simultaneously implanted. She was treated with systemic antibiotics—isoniazid, rifampin, ethambutol—for 2 weeks. Six months later she was healthy, pacing well, and apparently free of infection, off all medications.
Validation of a Method for Choice of Pacing Mode in Carotid Sinus Syndrome With or Without Sinus Bradycardia
Authors: BRIGNOLE MICHELE , MENOZZI CARLO , LOLLI GINO , ODDONE DANIELE , GIANFRANCHI LORELLA , BERTULLA ANTONIO
Published: July 2006

A new method for selection of the pacing mode in 60 consecutive patients with severe cardie‐inhibitory or mixed carotid sinus syndrome was prospectively validated. ODD pacing was preferred for 26 patients with: (1) the cardioinhibitory form and who had symptomatic pacemaker effect; (2) mixed type I form, (cardioinhibitory and vasodepressor) with symptomatic pacemaker effect, ventriculoatrial conduction or orthostatic hypotension; (3) mixed type II; or (4) severe bradycardia. VVI pacing was seiected in the remaining 34 patients without these symptoms. During a 32 ± 10 month follow‐up period syncope and severe dizziness persisted in five patients in the VVI group (15%) and in three patients in the ODD group (12%). Symptomatic relief occurred in 87% (52/60) of patients. Minor symptoms persisted in 47% of the VVI group and 42% of the DDD group. No patient developed cardiac insufficiency or intolerance to pacing. During a 2‐month duration a single‐blind, randomized, cross‐over study compared VVI and DDD pacing, 69% of the patients programmed from DDD to VVI suffered more frequent, severe, and intolerable symptoms. (1) Thirty four of 60 patients (57% of the entire group) in whom VVI pacing was satisfactory were identified prior to pacemaker implant. In the remainder, VVI pacing was contraindicated as it produced frequent side effects. (2) The preimplant predictive value that VVI pacing would be successful was 85% for those eventually receiving VVI pacemakers and the preimplant predictive value that VVI pacing would fail was 69% for those who underwent DDD implant.
Bandwidth‐Induced Errors in Parameters Used for Automated Activation Time Determination During Computerized Intraoperative Cardiac Mapping: Theoretical Limits
Authors: PIEPER CARL F. , LAWRIE GERALD , ROBERTS ROBERT , PACIFICO ANTONIO
Published: July 2006

Two parameters commonly used when determining the time of local activation during computerized Intraoperative cardinc mapping are the time of the peak in bipolar electrograms (BP) and the time of the largest negative slope (LNS) in monopoiar electrograms (MP). The dependence of these parameters upon bandwidth was studied. A database of fast MP and BP was compiled from intraoperative recordings collected from epicardial sock arrays in man. Based on 95%, 99% and 99.9% of total signal power, the faandwidths of each response were determined. After removing specified frequencies using the Fourier transform, errors in determining these parameters were computed and characterized with respect to mean square error (MSE), percent power bandwidth and frequency content. The Fourier transform was used for abruptly filter out undesired upper frequencies. Filtering BP at 200 Hz produced a 1‐ms shift in the peak in 17.0% of the electrograms, 0.4% of the peaks shifted by 2 ms and none shifted by more than 2 ms. Comparable shifts in the LNS occurred when filtering MP at 400 Hz. Retention of 95% of the power in a BP rarely (0.9%) changed the time of its peak by more than 1 ms. For MP, retention of 99.9% of the power was required for similar performance (3.6%). Thus, although BP have greater signal power in the higher frequencies than MP, a greater bandwidth is required when recording monopolarly in order to preserve the small amount of power necessary to define the time of the LNS with accuracy comparable to determination of the peak in BP.
Transvenous Placement of a Pacemaker Lead Through an Introducer Despite Long‐standing Subclavian‐Vein Occlusion
Authors: PARSONNET VICTOR , BONAVITA GREGORY J.
Published: July 2006

Under ordinary circumstances complete chronic subclavian vein occlusion precludes using that vein for the pacemaker lead. There are circumstances, however, in which a patent vein beyond the obstruction can be reached with an introducer needle, thus permitting transvenous access similar to any other introducer‐assisted implantation. A case exemplifying this point is described. Patency of the right subclavian vein beyond an occlusion was demonstrated by angiography, and a new dual‐chamber pacemaker lead was inserted through that site by use of the introducer method.
Long‐Term Community Hospital Experience with the Internal Defibrillator
Authors: PORTERFIELD JAMES G. , PORTERFIELD LINDA M. , BRAY LOUISE
Published: July 2006

Seventy‐seven patients with drug refractory ventricular tachycardia (57) and ventricular fibrillation (20) received the implantable defibrillator. There were 55 men and 22 women with a mean age of 63 ± 10 years. The anatomical diagnoses were coronary artery disease in 61 patients, cardiomyopathy in 15 patients, and aortic stenosis in one patient. The mean ejection fraction was 32 ± 12%. Concurrent surgery at defibrillator implantation was coronary bypass in eight patients and aortic valve replacement in one patient. There were no intraoperative mortalities. The mean ventricular fibrillation termination threshold was 13 ± 6 joules. During a follow‐up period of 16 ± 10 months (range 2‐40 months) four patients died: electrical mechanical dissociation (two patients), respiratory failure, and sepsis. Thirty‐eight patients (51%) continued receiving antiarrhythmic drug therapy, with quinidine sulfate and procainamide being the most frequently utilized agents. Fifty‐four patients (72%) have received a mean of 9 ± 10 shocks (range 1‐44). Implantable defibrillators are often needed in patients seen in large community hospitals. This technology can be administered successfully in this setting with complications and results comparable to those reported from university hospitals. Implantable defibrillators are effective in preventing arrhythmic death and can be used with low risk to the patients.
Occurrence of ICD Shocks and Patient Survival
Authors: ZILO PHILIP , GROSS JAY N. , BENEDEK MICHAEL , FISHER JOHN D. , FURMAN SEYMOUR
Published: July 2006

Fifty‐six consecutive patients who underwent initial implantation of an implantabie cardioverter defibrillator (AICD) between May 1982 and January 1990 were analyzed. During a mean follow‐up 0/31.5 ± 25 months, 32 (60%) patients experienced a spontaneous shock from their device. Their clnical characteristics and survival were compared to those of 21 patients without shocks. No statistically significant difference was found in the distribution between the two groups in age, sex, cardiac diagnosis, New York Heart Association Class, presenting arrhythmia, or mean follow‐up (F/U). The group with shocks had a higher incidence of previous MI (P = 0.021) a lower mean ejection fraction (P = 0.023) and had been tried on a greater number of medical regimens (P = 0.003). The 1‐, 3‐, and 5‐year cumulative survivals were 84%, 69%, and 37% in the group with shocks and 93%, 93%, and 93% for the group without shocks. Our data suggests that the occurrence of a shock is a negative prognostic indicator and that the excellent prognosis of patients without shocks contributes in large part to the favorable outcome of AICD patients.
Device Interaction—Antitachycardia Pacemakers and Defibrillators for Sustained Ventricular Tachycardia
Authors: AHERN THOMAS S. , NYDEGGER CHARLES , MCCORMICK DANIEL J. , MARINCHAK ROGER , KOWEY PETER , HOROWITZ LEONARD N. , WORLEY SETH , KUTALEK STEVEN P.
Published: July 2006

We evaluated the combined use of permanent automatic antitachycardia pacemakers and implanted defibrillators in fen patients with recurrent monomorphic sustained ventricular tachycardia (VT). Pacemaker programming was VVI‐T automatic burst in eight patients, VVI‐T magnet mode in one patient, and VVI in one patient. Device interactions occurred in four patients, requiring changes in pacemaker programming. These included defibrillator multiple counting during pacing, in‐appropriate pacemaker bursts initiating VT, inappropriate reset of the pacemaker antitachycardia mode by defibrillation, defibrillator discharge after pacemaker VT termination, and defibrillator VT reinitiation. Two patients required pacemaker programming out of the antitachycardia mode, and two required a change in antitachycardia pacing parameters. Seven patients remain in automatic VVI‐T and three in VVI modes. Mean follow‐up is 13 months and all patients are alive. Thus, although pacemaker/ defibrillafor combinations function well for patients with more than one VT rate, device interactions occur frequently and may require pacemaker reprogramming or elimination of the overdrive mode. Combined use of these devices should be cautiously considered when single device therapy is unsatisfactory. Devices that combine both pacing and defibrillation features may reduce adverse interaction.
The Impact of Antitachycardia Pacing with Defibrillation
Authors: LÜDERITZ BERNDT
Published: July 2006

Chronic recurrent ventricular tachycardia (VT) can be reproducibly terminated by programmed endocardiaJ right ventricular stimulation. However, antitachycardia pacing can be associated with possible acceleration of VT, while frequent episodes of VT and patient discomfort can limit treatment by an implantable cardioverter defibrillator (ICD). The combined use of antitachycardia pacing and the AICD (automatic implantable cardioverier defibrillator) was evaluated in 6 out of 51 patients (age 57 ± 11 years) in whom the AICD had been implanted because of recurrent VT. In each instance VT could be terminated by temporary overdrive pacing. The interactive mode of VT termination by a pacemaker (Tachylog) as well as by the AICD was assessed after implantation. In the automatic mode, the Tachylog functioned as a bipolar, ventricular inhibited (VVI) device with antitachycardia burst stimulation capability, allowing two to five stimuli at intervals of 260–300 ms and one or two interventions. During follow‐up of 47 ± 24 months, the Tachylog terminated VT reliably 50–505 times per patient. When burst stimulation accelerated VT, termination was achieved by AICD discharge. Thus, drug resistant VT can be terminated by antitachycardia pacing to avoid patient discomfort. In the event of tachycardia acceleration, VT was terminated by the AICD. A universal pacemaker‐defibrillafor should combine antibradycardia and antitachycardia pacing with back‐up cardioversion defibrillation.
Implantable Cardioverter Defibrillator: Data Storage and Retrieval with Patientlog
Authors: JORDAENS LUC , OLSSON ÖSTEN , VAN DE BRUAENE FRANK , FIERS TOM
Published: July 2006

A pacemaker management system (Patientlog), implemented on a IBM personal computer (AT), was adapted for the control and the administrative management of patients with an implantable cardioverter defibrillator (ICD). Several parameters used for pacemakers were also suitable for ICDs, while some fields were defined within the available frame of the database, to cope with the specific technical information of ICDs. “Intervention‐cards” display diagnostic (threshold) as well as complex surgical information (approach, lead systems, etc.). “Follow‐up‐cards” present charge time and the number of shocks in such a way that decision making is very easy. Fourteen patients were followed with a total of 21 interventions, six different types of devices, and more than 150 follow‐ups. A correct control of ICD functions is easy. The system is adapted for programmable ICDs. Updated reports containing necessary information are generated immediately after each procedure or follow‐up.
Biosensor Applications to Antitachycardia Devices
Authors: COHEN TODD J. , LIEM L. BING
Published: July 2006

Current arrhythmia detection algorithms are unable to adequately distinguish stable from unstable tachycardias; therefore application of a biosensor to antitachycardia devices has been proposed to improve their performance, Right heart pressures and impedance have been investigated for incorporation into these systems. Integration of other parameters (oxygen saturation, preejection period, pH, cardiac output, flow, and temperature) into these devices might also prove useful. The status of these biosensor arrhythmia detection algorithms and their application to antitachycardia devices are described below.
A Time‐Domain Analysis of Intracardiac Electrograms for Arrhythmia Detection
Authors: DICARLO LORENZO A. , THRONE ROBERT D. , JENKINS JANICE M.
Published: July 2006

The analysis of intracardiac electrogram morphology has been proposed as a complementary method for accurate discrimination between sinus rhythm (SR), supraventricular dysrhythmias, and ventricular dysrhythmias by automatic antitachycardia and cardioverter defibrillator devices. In this study, the performance of a traditional time‐domain method for surface electrocardiogram interpretation—Correlation Waveform Analysis (CWA) and a newly developed technique—Bin Area Method (BAM) were used to analyze unfiltered intraatrial and intraventricular electrograms obtained from 47 patients during routine cardiac electrophysiology studies. Nineteen patients had 31 distinct, sustained, monomorphic ventricular tachycardias (VTs) induced; 13 patients had paroxysmal bundle branch block of supraventricular origin (BBB) induced; 19 patients had retrograde atrial activation during ventricular overdrive pacing. Three patients were common to two or more groups. Using a best fit electrogram alignment, both CWA and BAM distinguished VT from SR in 28/31 cases (90%), BBB from SR in 15/15 patients (100%), and anterograde from retrograde atrial activation in 19/19 patients (100%J. We conclude that the use of time‐domain techniques that are independent of amplitude and baseline fluctuations appear to be reliable for discrimination of retrograde atrial activation, paroxysmal BBB, and VT from SR using intracardiac electrograms. Reduction of computational time and power constraints, without sacrificing reliable dysrhythmia discrimination, is possible. These features may make real‐time morphology analysis of intracardiac electrograms feasible for automatic antitachycardia and cardioverter‐defibrillator devices.
Long‐Term Testing of Defibrillator Batteries
Authors: HOLMES CURTIS F. , VISBISKY MARK
Published: July 2006

This article describes the life testing of lithium/silver vanadium oxide de/ibrillator batteries. Batteries were tested at 37°C under conditions which simulate ciinical conditions. A total of 788 cells are currently under test. No failures have been observed, and cells are performing normally.