bluuebunny/crossref_metadata_2025 huggingface dataset:
Rhythmic and Electrophysiological Study After Dynamic Cardiomyoplasty
Authors: RADERMECKER MARC A. , WALEFFE ANDRÉ , GOBIN ERIC , GRANDJEAN PIERRE , FOURNY JACQUES , KULBERTUS HENRI , LIMET RAYMOND
Published: July 2006

To question the possible proarrhythrnic effects of cardiomyoplasty (CMP), six adult goats were submitted to rhythmic and electrophysiohgical (EP) study 15 days before and 8 months after a posteroanterior clockwise CMP procedure using Medtronic± Cardiomyostimulator (CMS) (SP1005) and electrodes (SP5528) and completion of a progressive stimulation protocol. Pre and postoperative screening included a surface ECG, 24‐hour Hotter monitoring, high amplitude and filtered QRS averaging, and invasive EP study performed in the postoperative period with the CMS “ON” and “OFF.” One‐hour Hotter recording with desynchronization of the CMS was obtained. Comparison of pre and postoperative ECG and rhythmic data showed no significant difference. High amplitude QRS averaging did not evidence meeting the usual criteria of late potentials. EP values were stable in both conditions and the aggressive EP program did not show evidence of increased susceptibility to arrhythmias. Asynchronous cardiomyostimulation did not induce arrhythmias. Our data strongly suggest that provided meticulous surgical technique is used, CMP does not significantly interfere with the electrical characteristics of the normal goat heart. The procedure, despite the disturbances it provokes, does not seem to be arrhythmogenic. The function of the CMS was always appropriate, even under stressful EP conditions.
Subclavian Crush Syndrome Complicating Transvenous Cardioverter Defibrillator Systems
Authors: ROELKE MARC , O'NUNAIN SEAN S. , OSSWALD STEFAN , GARAN HASAN , HARTHORNE J. WARREN , RUSKIN JEREMY N.
Published: July 2006

Subclavian crush syndrome, described with pacemaker leads implanted via subclavian puncture, may occur when conductor fractures and insulation breaches develop by compression of a lead between the first rib and clavicle. We reviewed our experience in 164 patients who underwent intended implantation of transvenous defibrillator systems to determine the clinical relevance of subclavian crush syndrome in defibrillator patients. Venous access was obtained via subclavian puncture in 114 patients (70%) and via cephalic cut‐down in 50 patients (30%). Nonthoracotomy lead systems, with or without subcutaneous patch, were successfully implanted in 131 of 164 patients (79.9%). Thoracotomy was required in 32 patients (19.5%) and subxiphoid patch in 1 patient (0.6%). Over a mean of 12.9 months (range 1–62 months), 3 patients (1.8%) required revision of the rate sensing lead/coil or superior vena cava coil after development of lead compression fractures in the region of the clavicle and first rib. In all 3 patients the leads had been implanted via subclavian puncture (2.6% of patients in whom the subclavian technique was utilized). Two patients presented with spurious shocks. One patient was asymptomatic. Conclusions: When venous access is obtained via subclavian puncture, subclavian crush syndrome may develop in patients with transvenous defibrillator systems. Patients may be asymptomatic and lead fractures may go unrecognized. When implanting transvenous defibrillator systems, strong consideration should be given to obtaining venous access primarily via the cephalic cut‐down technique.
Hemodynamics of Idiopathic Paroxysmal Atrial Fibrillation
Authors: ALBONI PAOLO , SCARFŒ SALVATORE , FUCÁ GIUSEPPE , PAPARELLA NELLY , YANNACOPULU PANAYIU
Published: July 2006

The hemodynamics of induced atrial fibrillation (AF) was investigated in 15 patients (ages 58 ± 11 years) with paroxysmal AF presenting without organic heart disease or hypertension. A hemodynamic study was performed both during sinus rhythm and after the induction of AF. The mean heart rate increased from 73 ± 11 to 128 ± 18 beats/min (P < 0.001) after AF. Systolic and mean aortic pressures did not significantly change, and diastolic aortic pressure increased (78 ± 11 vs 89 ± 12 mmHg, P < 0.01). Left ventricular enddiastolic pressure decreased during AF (9 ± 3 vs 6 ± 2.6 mmHg, P < 0.005), whereas mean pulmonary wedge pressure increased (8 ± 2 vs 12 ± 4 mmHg, P < 0.001). Systolic pulmonary arterial pressure did not show significant variations, and there was a slight but statistically significant increase in the diastolic and mean pulmonary arterial pressures (P < 0.01). The right ventricular end‐diastolic pressure decreased during AF (5.6 ± 2 vs 3.8 ± 2 mmHg, P < 0.01 j, whereas mean right atrial pressure showed a trend toward an increase. Stroke volume markedly decreased (P < 0.001) while the cardiac index did not significantly change. Systemic vascular resistance, pulmonary arteriolar resistance, and the arteriovenous O2 difference showed no significant variations after the induction of AF. These results suggest that in subjects without organic heart disease, paroxysmal AF is well tolerated hemodynamicaily, and the rise in the atrial pressures during AF is not related to an increase in the ventricular end‐diastolic pressure.
Multicenter Experience With a Bipolar Tined Polyurethane Ventricular Lead
Authors: HAYES DAVID L. , GRAHAM KEVIN J. , IRWIN MARLEEN , VIDAILLET HUMBERTO , DISLER GAIL , SWEESY MARK , KINCAID DAN , OSBORN MICHAEL J. , SUMAN VERA J. , NEUBAUER SHARON A. , SEEBANDT MARY , KALLINEN LINDA
Published: July 2006

A multicenter study was undertaken to determine the failure rate of a specific bipolar tined polyurethane ventricular pacing lead, the Medtronic 4004/4004M pacing lead. Seven centers in the United States and Canada implanted 586 Medtronic 4004/4004M pacing leads. The study was designed to determine the probability and clinical manifestations of lead failure. Only failures compatible with an insulation problem were included. The Kaplan‐Meier estimate of the percentage of 4004/4004M lead failures within 4 years after implantation was 14.1% (95% confidence interval: 8.5%–19.3%). Failures were manifested as sensing abnormalities, failure to capture, early battery depletion, and significant decrease in measured impedance compared with previous impedance measurements. The observed rate of failure is unacceptable, and strong consideration should be given to replacing the 4004/4004M pacing lead in pacemaker dependent patients and closely monitoring nondependent patients.
A Verified Report of Spurious Programming: A Case Study
Authors: ERICKSON STEVEN L. , SWEESY MARK W. , FORNEY RICHARD C. , CALABRIA DOMINICK A.
Published: July 2006

A case of unintentional misprogramming is described in which a DDDR pacemaker, programmed to the VVIR mode, reverted to the originally programmed parameters and mode. The misprogramming requires that a particular sequence of steps be followed and has been verified by the manufacturer. This misprogramming may be clinically significant and can be reproduced in an entire family of current pacemakers based on the same software platform.
Polymorphic Ventricular Tachycardia Induced During Tilt Table Testing in a Patient with Syncope and Probable Dysfunction of the Sinus Node
Authors: GATZOULIS KOSTAS A. , MAMARELIS IOANNIS E. , APOSTOLOPOULOS THEODOROS , DILAVERIS POLECHRONIS , And JOHN GIALAFOS. , TOUTOUZAS PAVLOS
Published: July 2006

We present a case of life‐threatening arrhythmia occurring during tilt table testing in a 44‐year‐old man with syncope. Polymorphic ventricular tachycardia occurred while the patient was tilted up under the intravenous infusion of isoproterenol (2 μg/min). No ischemia, QTc prolongation, or electrolyte abnormality preceded this event. The arrhythmia was not induced by programmed ventricular stimulation or exercise testing. Based on electrophysiological and clinical data, the diagnosis of sick sinus syndrome was entertained.
Is There a Risk for Interaction Between Mobile Phones and Single Lead VDD Pacemakers?
Authors: NOWAK BERND , ROSOCHA STEFAN , ZELLERHOFF CHRISTIAN , LIEBRICH ANDREAS , HIMMRICH EWALD , VOIGTLÁNDER THOMAS , MEYER JÜRGEN
Published: July 2006

Mobile phones may cause pacemaker interference. Patients with a single lead VDD pacemaker might be at special risk, since the atrial sensitivity is often programmed to low (high sensitivity) threshold values and the majority of patients are pacemaker dependent due to the underlying high degree AV block. We evaluated 31 patients with three types of single lead VDD pacemakers: 12 Unity, 292–07 (Intermedics, Inc.); 10 Thera VDD, 8948 or 8968i (Medtronic, Inc.); and 9 Saphir 600 (Vitatron, Inc.) for interference from a cellular mobile phone with a power of 2 W (D‐net). For this purpose, atrial and ventricular sensitivity settings were programmed to their most sensitive values (A: 0.1–0.25 mV; V: 1.0 mV) and ventricular sensing was programmed to unipolar. With the ECG continuously monitored, the phone's extendable antenna was brought in direct contact with the patient's skin at the right sternal border, with the tip of the antenna in skin contact just below the clavicle, within 5 cm of the pacemaker connector. Then multiple phases of phone calls were performed, and the effects on the pacemakers recorded. In our group of patients with three different types of single lead VDD pacemakers, no interference could be detected using a 2‐W mobile phone in the digital D‐net. The programmed values remained unchanged after the interference test. Therefore, the risk of interference seems to be low for the VDD pacemakers tested, although our study design does not allow to entirely exclude the possibility of interference from a mobile phone.
The Safety of Digital Mobile Cellular Telephones with Minute Ventilation Rate Adaptive Pacemakers
Authors: SPARKS PAUL B. , MONO HARRY G. , JOYNER KENNETH H. , WOOD MICHAEL P.
Published: July 2006

In vitro tests suggest that rate adaptive pacemakers using changes in transthoracic impedance to vary pacing rate may be affected by digital mobile telephones. Electromagnetic fields generated by digital mobile telephones (Global System for Mobile [GSM]) represent a potential source of electromagnetic interference (EMI) for the Telectronics META rate adaptive pacemakers, which use transthoracic impedance as a sensor to determine changes in minute ventilation. Sixteen implanted Telectronics META pulse generators were exposed to 25‐W simulated GSM transmissions (900‐MHz carrier pulsed at 2, 8, and 217 Hz with a pulse width of 0.6 ms) and the antenna of a 2‐W digital mobile telephone (900‐MHz, 217‐Hz pulse. 0.6‐ms pulse width). The 12 dual and four single chamber devices were programmed to maximum sensitivity and assessed in unipolar and bipolar settings and rate adaptive and nonrate adaptive modes. In all cases of EMI, testing was repeated at lower, more routinely set bipolar sensitivity levels. At maximum sensitivity, 11 of 16 devices displayed no evidence of EMI. Brief ventricular triggering occurred in 2, a brief pause in 1, a combination of both in 1, and a brief episode of pacemaker‐mediated tachycardia in 1. With pulse generators programmed to more routine sensitivities, only one device displayed rare single beat ventricular triggering. No changes in minute ventilation rate adaptive pacing were observed. At maximum unipolar sensitivities, the META series of rate adaptive pacemakers are resistant to clinically important EMI from digital mobile telephones. Set at routine sensitivities, these devices perform reliably in the presence of digital mobile telephones.
The Impact of Pulse Generator Longevity on the Long‐Term Costs of Cardiac Pacing
Authors: GILLIS ANNE M. , MacQUARRIE DAVID S. , WILSON SUZANNE L.
Published: July 2006

The long‐term costs of cardiac pacing include the device costs, the procedural costs, the follow‐up costs, and the replacement costs. At present, there is significant variability in the efficiencies of the integrated circuits and the total battery capacity among different pulse generators that will influence replacement rates over time. Accordingly, we compared the influence of pulse generator longevity on the long‐term costs of pacing. The longevity of pulse generators was calculated based on the electrical characteristics of the device and the percentage of time the patient is paced. Replacement rates of pulse generators were estimated for our patient population over a 20‐year period, based on patient survival and pulse generator longevity. The costs of pacing over this 20‐year follow‐up period were then calculated. The longevity of DDDR devices presently implanted in the United States ranges from 8–14 years, assuming that patients are paced 50% of the time. Replacement rates in this population over a 20‐year follow‐up period were calculated to range from 0.34–0.66, and the total costs of pacing would range from $11,898–14,900 per patient. The longevity of SSIR devices ranges from 7–20 years, assuming that patients are paced 50% of the time. Replacement rates were calculated over the 20‐year follow‐up period to range from 0.20–0.84, and the total costs of VVIR pacing would range from $8,331–13,286. Based on the proportion of pulse generator models implanted in patients in the United States, the maximum cost differential to the health care system is approximately $424 million/year comparing the devices with the shortest and greatest longevities. Thus, pulse generator longevity may significantly influence the long‐term costs of pacing. Patient survival and pulse generator system longevity should be considered when selecting the appropriate pacing system for the individual patient.
Augmented Two‐Channel Arrhythmia Detection: An Efficient Diagnostic Method for Implantable Devices
Authors: CHIANG CHIH‐MING JAMES , JENKINS JANICE M. , CASWELL STEPHANIE A. , STEVENSON SHELLY A. , DiCARLO LORENZO A.
Published: July 2006

ICDs are highly effective in preventing sudden cardiac death. However, inappropriate device shocks caused by false‐positive diagnoses are estimated to happen in 20% of all patients. The need for implantable electrical devices to detect with precision arrhythmias requiring therapy has spawned a variety of proposals for better means of tachycardia identification. To address this problem, the augmented two‐channel arrhythmia detection (A2CAD) algorithm, a real‐time scheme utilizing timing and morphology from both the atrial and ventricular channels, is introduced. The algorithm uses rate detection as a first stage and augments this with morphological signal analysis in rhythms that confound the rate only diagnoses. The software executes in real‐time (online), and has been tested on 60 passages of two‐channel intracardiac signals. The following arrhythmias constituted the test set: 10 AF and/or atrial flutter; 15 SVT; 16 VT; 10 ventricular flutter or VF; 5 sinus tachycardia; and 4 cases of AF concurrent with VF. Results from 60 patient cases indicate 57 (95%) of 60 success rate for A2CAD, validating its potential for implementation in future implantable devices.
Setting of Relatively Low Energy Outputs May Permit Implantation of a Nonthoracotomy Automatic Cardioverter Defibrillator System When High Energy Outputs Prove Ineffective
Authors: WINTERS STEPHEN L. , CASALE ALFRED S. , INGLESBY THOMAS V. , CURWIN JAY H.
Published: July 2006

At intraoperative testing of defibrillation thresholds during implantation of internal Cardioverter defibrillators, standard step‐down approaches of energy outputs are used. If relatively high energy outputs are not successful at defibrillating the heart, the electrodes are frequently reconfigured. When attempting implantation of a nonthoracotomy lead system, high defibrillation thresholds may warrant opening of the chest cavity to place one or more epicardial electrodes. A case is presented where a nonthoracotomy system was able to be implanted using relatively low energy outputs which were reproducibly successful at terminating ventricular fibrillation when higher energy outputs were unsuccessful. Mechanisms for this phenomenon and alternate recommendations for defibrillation testing are presented.
Implantable Cardioverter Defibrillator Clinic Casualties: Inadvertent Reprogramming During Routine Implantable Cardioverter Defibrillator Follow‐Up
Authors: OZAHOWSKI TOMAS P. , GREENBERG MARK L. , MOCK PATRICIA , HOLZBERGER PETER T. , GERLING BARBARA , ZALINGER CAROL , PERRY CATHRINE
Published: July 2006

On one occasion during a busy ICD follow‐up clinic, the preceding patient's parameters for rate, PDF, and delay were inadvertently programmed into the subsequent patient's generator using the CPIProgrammer Model 2035. This occurred after capacitor reformation, without pressing the “Program” button. The source of this reprogramming error was failure to clear the programmer memory of the previous patient's data, usually achieved by turning the programmer off between patients (or selecting “New Patient” from the menu). At our next ICD follow‐up clinic, we purposely did not turn off the programmer between two sets of patients. On both occasions the above finding was repeated and confirmed. These observations indicate the potential for serious reprogramming errors that can occur simply by not clearing the programmer's memory between clinic patients.
Amiodarone Induced Hyperthyroidism: A Case Series and Brief Review of Literature
Authors: HARJAI KISHORE J. , LICATA ANGELO A.
Published: July 2006

To delineate the incidence, clinical features, diagnosis, and treatment options for amiodarone induced hyperthyroidism (AIH), we reviewed the medical records of ten patients with AIH. Eight of these 10 patients were detected on initial review of the records of 200 patients in treatment with amiodarone, and the other 2 following notification by their endocrinologists. AIH occurred in 4.2% of patients beingtreated with amiodarone. At the time of diagnosis of AIH, the mean (SD) values for age, duration of treatment with amiodarone, and dose of amiodarone were 62.9 (8.96) years, 38.3 (20) months, and 366.7 (122) mg/day, respectively. The most common clinical features were weight loss and goiter (each seen in 90% of patients). Serum thyroxine (T4), triiodothyronine, and free thyroxine index (FTI) showed an increase of 84%, 47%, and 110%, while thyroid stimulating hormone (TSH) and resin T4 uptake decreased 96% and 14%, respectively, from previous values. The most consistent laboratory findings, seen in all patients, were subnormal TSH and abnormally high FTI. One patient required no treatment; another underwent prompt total thyroidectomy. The other eight were treated medically; two of them underwent total thyroidectomy later, for medical failure or adverse effects. Amiodarone was continued in four patients. The most commonly used antithyroid medication was propylthiouracil. AIH presents in the early or late phases of treatment with amiodarone with typical clinical features of a hyperthyroid state, fall in TSH, and increase in FTI. Antithyroid medications are reasonably effective in the management of AIH.
Quality‐of‐Life in Patients Receiving Implantable Cardioverter Defibrillators At or Before Age 40
Authors: DUBIN ANNE M. , BATSFORD WILLIAM P. , LEWIS RICHARD J. , ROSENFELD LYNDA E.
Published: July 2006

As the use of ICDs increases, more young patients will be eligible to receive these devices. Such patients may have different concerns than older patients who more commonly receive ICDs. We investigated quality‐of‐life issues in patients followed by the Yale electrophysiology service who were ≤ 40 years old (mean = 28) at the time of ICD implant. Mean time since ICD placement was 3.3 years. Each patient received a modified SF‐36 health questionnaire; 16 (88%) of 18 responded. Nine were women; ten were married. The highest education level attained was high school for 6 (37%), and college or beyond for 10 (63%). Ten patients were employed; eight held the same job before and after ICD placement. Four women conceived after ICD implantation; one experienced ICD discharge during pregnancy. All delivered healthy infants. AH patients felt their health was good to excellent, with 6 (38%) reporting an improvement in health since ICD placement. All felt capable of performing the activities of daily living, while 68% engaged freely in moderate physical activities. All patients felt they were average to very attractive. However, 63 % worried about how their clothes fit with the ICD. Three quarters of the patients felt the ICD interfered with social interactions, while 50% were concerned about sexual encounters. Thus, even though these young patients have body image concerns and may limit their activities to some degree, they are productive, active members of society who have benefitted from ICD placement.
The Influence of Sodium Channel Blockade on the Defibrillation Energy Requirements of Diphasic Versus Monophasic Shocks
Authors: NELSON STEVEN D. , LENHART MICHAEL B. , SAFFARIN AMIR
Published: July 2006

The sodium channel‐blocking actions of some Class I antiarrhythmic agents can increase the defibrillation energy requirements (DER) of monophasic shock waveforms. The influence of sodium channel blockade on biphasic shocks is less certain. The purpose of this study was to compare, in a randomized, placebo controlled study, the influence of lidocaine on the DER of biphasic and monophasic shock waveforms in a canine model of transvenous internal defibrillation. The DER was determined by the iterative increment‐decrement protocol. Monophasic and biphasic shock DERs were tested at baseline and during lidocaine infusion (group A) or saline control (group B). Group A biphasic shock DERs increased significantly from a baseline of 12.1 ± 3.6 J to 19.1 ± 9.3 J when compared to group B (P = 0.005). In group A, the mean DER during lidocaine was significantly higher with monophasic shocks than biphasic shocks (29.6 ± 11.8 f vs 19.1 ± 9.3), respectively: P < 0.003), but the magnitude of change in biphasic versus monophasic shock DERs was not significantly different (F = 1.78; p = 0.193). There was a linear relationship between the baseline DER and the DER during lidocaine (r2= 0.63, P < 0.0001). Sodium channel blockade with lidocaine increases the DER of both monophasic and biphasic shocks. However, the DER of biphasic shocks during lidocaine are significantly lower than monophasic shock DERs, a finding that can be explained by the linear relationship between the baseline DER and the DER during lidocaine. These results may have favorable implications for the use of Class I antiarrhythmics with biphasic shock defibrillators.
Comparative Evaluation of Acute and Long‐Term Clinical Performance of Two Single Lead Atrial Synchronous Ventricular (VDD) Pacemakers: Diagonally Arranged Bipolar Versus Closely Spaced Bipolar Ring Electrodes
Authors: LAU CHU‐PAK , LEUNG SUM‐KIN , LEE IRIS SIU‐FONG
Published: July 2006

Floating P wave sensing can be derived from bipolar atrial electrodes with different electrode configurations, although the relative clinical efficacy of these methods of atrial sensing has not been studied. We evaluated 32 sex and age matched patients with advanced AV block who received A V synchronous pacers using either a single lead with diagonally arranged bipole (Unity VDDR, Model 292, Intermedics Inc.) or closely spaced bipolar complete ring electrodes (Them VDD, Model 8948, Medtronic Inc.). The total surface area of the atrial electrodes were 17.2 and 25 mm2, and the highest programmable atrial sensitivities were 0.1 and 0.25 mV, respectively. Atrial electrogram amplitude and sensing threshold were evaluated at implant and at each follow‐up clinic visit (1, 3, and 6 months), Stability of atrial sensing was assessed during physical maneuvers, treadmill exercise test, and Holier recording. Atrial electrogram amplitude at implantation was higher in the Them VDD (2.08 ± 0.79 vs 1,45 ± 0.59 mV in Unity VDDR; P < 0.05), but the value of atrial sensing threshold was lower during follow‐up than Unity VDDR. P wave undersensing was additionally observed with both pacemakers during physical maneuvers and exercise testing (6%‐19% of patients). Two and four patients had atrial undersensing on Holter in the Unity VDDR and Them VDD, respectively, and the percentage P wave undersensing were 0.88%± 2.41% versus 3.63%± 8.16%, respectively. Reprogramming of the atrial sensitivity in the Unity VDDR and the use of investigational software allowing 0.18 mV atrial sensitivity to be programmed in the Them VDD substantially reduced the percentage of P wave undersensing on Holter to 0.46%± 1.67% and 0.10%± 0.24%, respectively. Beginning at discharge with a programmed atrial sensitivity level at least twice the sensing margin, the mean atrial sensitivity level was reprogrammed from 0.29 to 0.26 mV for Unity VDDR and 0.33 to 0.24 mV for Them VDD at 6 months. There was no incidence of atrial oversensing. Despite differences in atrial amplitudes at implantation between the diagonally arranged bipole and closely spaced full ring single lead systems, the clinical performances of atrial sensing were similar at an appropriately high atrial sensitivities. The absence of atrial oversensing suggests that single pass VDD pacemakers should probably be programmed at the highest available atrial sensitivity to ensure adequate P wave sensing as guided by physical maneuvers and Holter recording to minimize the need of subsequent reprogramming.
The Importance of Different Atrioventricular Delay for Left Ventricular Filling in Sequential Pacing: Clinical Implications
Authors: MODENA MARIA GRAZIA , ROSSI ROSARIO , CARCAGNÌ ADDOLORATA , MOLINARI ROSELLA , MATTIOLI GIORGIO
Published: July 2006

We assessed the influence and clinical consequences of different AV delay on ventricular filling in 30 patients (mean age 60 ± 5 years) who had ODD pacemakers for AV block. All 30 patients presented a normal ejection fraction, but in 18 cases (Group I), an echo‐Doppler examination revealed ventricular hypertrophy (mean end‐diastolic wall thickness of 1.4 ± 0.16 cm. LV mass index 155 ± 17g/m2), and an abnormal relaxation pattern (isovoiumetric relaxation time = 124.72 ± 11.82; early to late peak velocity = 0.6 ± 0.03; deceleration time ‐ 296.83 ± 34.02 ms). Group II included the remaining 12 patients who had a normal filling pattern. In all 30 patients, the pattern was reassessed following modification of the AV delay (200, 150, 100. and 75 ms). Patients at baseline (AV delay of 200 ms) also underwent an exercise test with determination of respiratory gas exchange. In Group I, 13 (72.5%) patients were classified as Weber class B (VO2 Max 16.8 ± 1.7mL/min per kg); and 5 (27.5%) were Class A (VO2 Max 22.5 ± 1.4 mL/min per kg). In Group II, all 12 patients were classified as Weber Class A. In Group II, changes in AV delay caused no consistent variations in filling pattern, and therefore AV delay was not modified. In Group I patients, since reduction to 100 ms resulted in normalization of the filling pattern, the AV delay was programmed to 100 ms. A graded exercise test repeated after 6 months follow‐up showed an improved Weber class in 13 patients (from B to A) and greater VO2 Max in the remaining five already in Class A. We concluded that, in sequential paced patients with normal ejection fraction but abnormal relaxation pattern, modification in AV delay can induce normalization of filling and improvement in cardiac functional capacity.
Radiation Doses During Pediatric Radiofrequency Catheter Ablation Procedures
Authors: GEISE RICHARD A. , PETERS NANCY E. , DUNNIGAN ANN , MILSTEIN SIMÓN
Published: July 2006

Because RF catheter ablation procedures may be lengthy and are commonly performed in young patients, concern has arisen about radiation dose in this group of patients. This article investigates radiation doses in pediatric patients undergoing RF catheter ablation. Standard fluoroscopic equipment used for diagnostic electrophysiological catheterization studies is technologically capable of dose rates as high as 90 milligray (mGy) per minute to skin and adjacent lung and 260 mGy/min to vertebral bone. Dose rates of this magnitude when used for extended periods of time have been known to cause erythema, pneumonitis, and retardation of bone growth. We measured skin dose rates of nine pediatric patients undergoing RF catheter ablation for tachycardia and calculated doses to the skin using standard dosimetric methods. Fluoroscopic techniques and equipment were studied using a patient simulating phantom. Overlap of fluoroscopic fields was checked using radiotherapy portal verification film, and regions in which doses overlapped from multiple angle exposures were verified using a treatment planning computer. Patient skin dose rates ranged from 6.2–49 mGy/min for patients ranging in age from 2–20 years. Maximum skin doses ranged from 0.09–2.35 Gy. Our data demonstrate the need to directly measure dose rates for individual fluoroscopic equipment and procedural techniques in order to determine whether limitations need to be set for procedural times.
If Dr. Bazett Had Had a Computer…
Authors: MALIK MAREK
Published: July 2006

The original data of 109 pairs of RR and QT intervals published by Dr. Bazett in 1920 were subjected to a computerized optimization of the QT/RR relationship. Four generic formulae expressing QT interval as α+βRRμ, α+βeμRR, α+βe(1/μRR), and α+βelnμ(10 × RR) were used, and for each formula, optimum combinations parameters α, β, and μ were established that lead to minimum differences between the actual QT interval intervals and values predicted by the model. The results show that independent of the generic formula used, parameters of the model can be selected that provide a close fit of the measured values. Compared to the optimum models obtained in this way, the optimum fit of the Bazett model, QT =βRRl/2, overestimates the QT intervals for slow heart rates. In addition to demonstrating the procedure of obtaining an optimum QT/RR model for a given data set, the study suggests that critical understanding of the principal limitations of every QT/RR model is more important than its mathematical form.
Effect of Pentaphasic Pulse Sequence as an Impedance Sensor on Standard Electrocardiographic Recordings
Authors: MORTAZAVI SAID , PARK EULJOON , FLORIO JOSEPH , POORE JOHN , BORNZIN GENE , LEVINE PAUL A. , SHOLDER JASON
Published: July 2006

Two advances in cardiac pacing have resulted in an internal conflict in some pacemakers. One is the development of a standard lead physiological sensor and the other is protection from electromagnetic interference (EMI). One popular type of standard lead sensor uses sub‐threshold pulses to measure intracardiac and intrathoracic impedance changes, i.e., minute ventilation. Recent clinical observations and extensive in vitro testing have verified that digital cellular phones can be troublesome. Large feedthrough capacitors (FCs), effective in blocking the EMI, will preclude sensing of the standard impedance‐based signals. A variety of pulse configurations were studied that might be effective for a sensor‐based impedance signal while allowing the pacemaker to continue to use large Fcs protecting them from environmental EMI. In comparison to both monophasic and biphasic pulse sequences, a pentaphasic pulse sequence was effective as an impedance sensor, still allows large FCs to function as an effective filter for environmental EMI, and would not produce artifacts on surface ECG.
Is Local Myocardial Contractility Related to Endocardial Acceleration Signals Detected by a Transvenous Pacing Lead?
Authors: BONGIORNI M.G. , SOLDATI E. , ARENA G. , QUIRINO G. , VERNAZZA F. , BERNASCONI A. , GARBEROGLIO B.
Published: July 2006

The availability of sensors monitoring cardiac function parameters may offer many interesting new applications in cardiac pacing. A microaccelerometer sensor (BEST, Biomechanical Endocardial Sorin Transducer) located at the tip of a pacing lead (PL) has been developed by Sorin Biomedica. The signal detected by the accelerometer, peak Endocardial acceleration (PEA), was shown to reflect cardiac contractility and to be related to the dP/dt signal. Whether the PEA detected by the BEST sensor in different cardiac locations is the expression of local acceleration forces or reflects the whole heart contractility has not yet been demonstrated in humans. Endocardial acceleration and PEA were evaluated in five patients (4 males, 1 female, mean age 68 years) who underwent cardiac catheterization. Sinus rhythm was present in four patients and chronic atrial fibrillation was present in one. The BEST PL was introduced through the left subclavian vein and PEA signals were recorded: (1) at the apex of the right ventricle (RV), (2) within the coronary sinus (CS), (3) at the right atrial appendage (RAA), and (4) floating in the right atrium. The PEA signals were recorded simultaneously with surface ECG, intracardiac electrograins, and RV pressure. At each recording site, PEA signals with significant amplitude were always recorded during the preelection period, during the isovolumic contraction phase, independently of the recording site and cardiac rhythm. The PEA amplitude was higher in the RV (mean value 1.32 g) and it decreased in the RAA and CS (0.75 and 0.45 g, respectively). The same behavior of PEA was observed during sinus rhythm or atrial fibrillation. The amplitude and the timing of the PEA signals detected by the BEST accelerometer were independent of the recording site and atrial rhythm; they appeared to be strictly related to the global ventricular contractility. These results suggest that the BEST could be used either as an effective sensor in closed loop pacing systems, or primarily as a diagnostic hemodynamic sensor.
A Prospective Multicenter Study Demonstrating Clinical Benefit with a New Accelerometer‐Based DDDR Pacemaker
Authors: LAZARUS ARNAUD , MITCHELL KEVIN ,   for the DROMOS DR INVESTIGATORS GROUP
Published: July 2006

From November 1994 to October 1995, 63 patients (average age 66 years; 41 men) from 15 centers implanted with the Biotronik Dromos DR and Ergos TC 03 pulse generators were prospectively screened with an exercise test in the DDD mode for the presence of chronotropic incompetence (CI). Both pulse generators incorporate an identical accelerometer‐based motion sensor. CI was defined as a maximum heart rate < 60% of age predicted maximum heart rate or 100 beats/min. Twenty‐five patients (40%) met the criteria for CI. Two weeks later, CI patients were required to complete paired metabolic exercise testing in the DDD and DDDR modes on consecutive days with a 24‐hour rest period. The order of testing was randomized and performed double blinded to minimize potential biases. Three patients who did not reach the anaerobic threshold (AT) and one patient who was unable to perform the metabolic testing were excluded from the analysis. Compared to the DDD mode, there were statistically significant improvements in the DDDR mode for all five endpoints: heart rate (84 ± 3.6 vs 113 ± 3.5 beats/min; P < 0.0001); total exercise time (8.23 ± 0.71 vs 9.15 ± 0.65 min; P = 0.0005); maximum VO2 (17.76 ± 1.36 vs 20.43 ± 1.75 mL/kg per min; P = 0.0001); V02 at AT (13.1 ± 0.87 vs 14.59 ± 0.79 mL/kg per min; P < 0.01); and exercise time to AT (5.65 ± 0.61 vs 6.33 ± 0.53 min; P = 0.02). In conclusion, the results of paired metabolic exercise tests with the Dromos DR and Ergos TC 03 pulse generators demonstrate a clear clinical benefit using the accelerometer‐based sensor in the CI patient
Improved Accelerometer‐Based Rate Adaptive Pacing by Means of Second‐Generation Signal Processing
Authors: SCHMIDT MATTHIAS , AMMER RICHARD , EVANS FRED , PASQUANTONIO JAY , SOTTS LARRY , GRIMES JOHN , SCHÖMIG ALBERT , ALT ECKHARD
Published: July 2006

Accelerometer‐based rate adaptive pacing has gained widespread clinical use. Limitations exist for the distinction between walking upstairs and downstairs. It was the aim of this study to evaluate a new signal processing algorithm for more physiological rate adaptation. A custom‐made pacemaker incorporating an accelerometer was randomly fixed to the left or right chest of 16 pacemaker patients (7 females, age: 64 ± 11 years), 18 elderly study participants (6 females, age: 62 ± 11 years), and 15 students (7 females age: 23 ± 2 years). Study participants walked on level ground, upstairs and downstairs at five different step rates (72, 84, 96, 108, and 120 steps/min) controlled by an acoustic quartz metronome. The accelerometer signals, recorded on a portable data recorder, were analyzed with respect to frequency content, peak average of the mean acceleration, and morphology characteristics of the acceleration signal above and belowzero baseline. By calculating the quotient of the signal's duration above and below zero baseline, a reliable discrimination between walking upstairs and downstairs was possible. A correction of the Leaky integrator signal by the new quotient yielded a more adequate rate adaptation to walking up and downstairs to represent at the patient's daily life activities. A more physiological rate adaptation can be achieved when using not only the accelerometer signal's amplitude, but applying additionally the morphology criterium of the acceleration signal's content in the positive and negative direction.
Evaluation of a New Pacing Algorithm to Prevent Rapid Tracking of Atrial Tachyarrhythmias
Authors: KAMALVAND KAYVAN , KOTSAKIS ATHANASIOS , TAN KIM , BUCKNALL CLIFF , SULKE NEIL
Published: July 2006

The new SMARTracking (SMT) algorithm was evaluated in seven patients with the Intermedics Relay DDDE pacemakers and a history of atrial tachyarrhythmias. The SMT algorithm uses the sensor calculated rate to define a physiological band whose upper limit is defined by the SMT rate. Pacemakers were programmed to DDDR with SMT (DDDRSM), DDDR with Conditional Ventricular Tracking Limit (DDDRC), DDDR with standard upper rate behavior, and VVIR, for a period of one month each. Patients underwent a CAEP exercise test and 24‐hour ECG Holter monitoring in each mode. They also had ambulatory ECG monitoring during daily activities including rest, slow and fast walk, stairs ascent and descent. Three patients were in atrial fibrillation during the daily activities protocol. Their ventricular rates were paced and highly irregular, in both DDDRSM and DDDRC modes. The heart rate was lower in DDDRSM than DDDRC at rest and low levels of exercise but not during more strenuous activity. Two patients in DDDRSM and 3 in DDDRC requested early change of their mode due to unacceptable symptoms. Two patients exhibited Wenckebach behavior at atrial rates below the upper rate limit in both DDDRSM and DDDRC modes. In conclusion, CVTL or SMARTracking are not adequate protection against atrial tachyarrythmias in patients with DDDR pacemakers.
Reliability of a New Algorithm for Automatic Mode Switching from DDDR to DDIR Pacing Mode in Sinus Node Disease Patients with Chronotropic Incompetence and Recurrent Paroxysmal Atrial Fibrillation
Authors: RICCI R. , PUGLISI A. , AZZOLINI P. , SPAMPINATO A. , PIGNALBERI C. , BELLOCCI F. , ADINOLFI E. , DINI P. , CAVAGLIÀ S. , De SETA F.
Published: July 2006

To evaluate the safety and efficacy of a new algorithm for automatic mode switching (AMS) from DDD‐DDDR to DDIR, 26 patients, 16 females and 10 males, mean age 73 ± 6 years of age, affected by sinus node disease, chronotropic incompetence, and recurrent paroxysmal atrial fibrillation (PAF) received the Medtronic Them DR pacemaker. The device continuously calculates, in ms, the running average of the intrinsic atrial rate (MAR) and compares the current atrial interval (CAI) with the stored MAR. When the CAI is greater than the MAR it increases by 8 ms, and when the CAI is less than the MAR, it decreases by 23 ms. When MAR ± 330 ms (182 beats/mm), tachycardia is detected and AMS is activated. All patients had clinical evaluation, 12‐lead ECG, Holter monitoring, and exercise testing after implantation and every 3 months for 1 year. The results were compared with the data stored in the pacemaker memory: AMS episodes number; the histogram of the last 14 episodes; and atrial electrogram recording. Twenty‐two Holier recordings in 13 patients showed PAF and in all of them AMS occurred simultaneously. AMS lasted between 10 seconds and 20 hours, and MAR ranged from 195–400 beats/mm. No episode of PAF and no AMS were recorded in 39 Holter recordings in 22 patients. Appropriate AMS was confirmed in five patients by stored atrial electrogram and in nine by 12‐lead ECG and pacemaker event markers. Mean atrial sensing was 2.13 ± 1.04 mV during PAF and 3,18 ± 1.46 mV during sinus rhythm. No PAF episode and no AMS were recorded during exercise testing. In conclusion, this new algorithm was very reliable, sensitive, and specific.
Single Lead DDD System: A Comparative Evaluation of Unipolar, Bipolar, and Overlapping Biphasic Stimulation and the Effects of Right Atrial Floating Electrode Location on Atrial Pacing and Sensing Thresholds
Authors: TSE HUNG‐FAT , LAU CHU‐PAK , LEUNG SUM‐KIN , LEUNG ZOE , MEHTA NAWZER
Published: July 2006

Single lead DDD pacing using unipolar or bipolar stimulation is limited by high atrial threshold. Overlapping biphasic (OLBI) waveform stimulation via atrial floating ring electrodes may preferentially enhance atrial pacing and avoid diaphragmatic pacing. Single lead DDD pacing with OLBI atrial pacing was studied in 12 patients (6 men and 6 women; mean age 74 ± 7 years) with complete heart block. At implantation, atrial bipolar rings (area 27 mm2, separation 10 mm) were positioned at radiological defined high, mid, and low right atrial (RA) levels, and P wave amplitude and atrial and diaphragmatic pacing thresholds were determined in each position using unipolar, bipolar, and OLBI stimulation in random order. Although statistically insignificant, both the maximum and minimum sensed P wave amplitudes tended to be lower in the low RA position. Independent of the stimulation modes, minimum atrial pacing threshold occurred in the mid‐RA. At mid‐RA. the atrial pacing threshold was significantly lower with OLBI pacing compared with either unipolar or bipolar mode (3.9 ± 2.2 V vs 6.7 ± 3.5 V and 6.9 ± 3.5 V, P < 0.05). Although the diaphragmatic thresholds were similar, OLBI pacing modes in the mid‐RA and final location significantly improved the Safety margin for avoidance of diaphragmatic pacing compared with unipolar mode. There was no correlation between atrial pacing and sensing threshold. At predischarge testing, all but one patient who developed atrial fibrillation had satisfactory atrial capture and a stable atrial pacing threshold (day 0: 2.6 ± 1.1 V vs day 2: 3.2 ± 1.3V, P = NS). However, diaphragmatic pacing occurred in four of 11 (36%) patients, especially in the upright position (sitting and standing). Our preliminary clinical results suggest that OLBI pacing via atrial floating ring electrodes can reduce the atrial pacing threshold. To optimize atrial pacing and sensing, the bipolar electrodes should be located at the mid‐RA level first, although the high RA is an alternative. Despite significant improvements in the safety margin for diaphragmatic pacing with OLBI pacing, diaphragmatic stimulation remains a clinical problem.
Optimized Standby Rate Reduces the Ventricular Rate Variability in Pacemaker Patients with Atrial Fibrillation
Authors: GREENHUT SAUL E. , FRASER JENNIFER , STEINHAUS BRUCE , FELD GREGORY , HUGHES WILLIAM
Published: July 2006

Patients with chronic atria! fibrillation (AF) and symptomatic bradycardia often receive ventricular‐based pacemakers. However, many of these patients continue to have symptoms of palpitations, which may be due to ventricular rate variability. It has previously been shown that contin uous ventricular pacing during AF has a stabilizing effect on the ventricular rate. Hence, a study was initiated to determine whether a patient‐specific optimal ventricular standby rate that reduces the ventricular rate variability, without over‐pacing, could be predicted. A ventricular rate stabilization (VRS) pacing algorithm that increases the pacing rate until instability is reduced below a threshold was developed. The VRS algorithm was utilized to determine a patient‐specific standby rate in 15 patients with chronic AF, intact AV nodal conduction, and implanted pacemakers. The computer algorithm controlled a pacemaker programmer to automatically change the pacemaker's ventricular pacing rate via telemetry. Patients were studied for 15 minutes with VRS and for 15 minutes with 50 ppm fixed rate pacing (control). The results were as follows: (1) VRS versus control = P < 0.05; (2) mean ventricular pacing rate (ppm): 77 ± 13 versus 50 ± 0; (3) mean ventricular rate (beats/mm); 82 ± 13 versus 79 ± 12; (4) ventricular rate coefficient of variation (%): 11 ± 1 versus 22 ± 5; (5) percent pacing: 75 ± 8 versus 6 ± 8; (6) percent of RR intervals less than minimum pacing interval eliminated: 58 ± 12; (8) regression analysis: mean VRS pacing rate (beats/min) = 0.96 X mean control ventricular rate + 2.3, r2= 0.85. We concluded that: (1) a moderate increase in the ventricular pacing rate was required to substantially stabilize the ventricular rate; (2) the resulting mean ventricular rate increased marginally: (3) a majority of RR cycles less than each patient's minimum pacing interval were eliminated; and (4) there was a linear relationship between the mean ventricular rate during control and the optimal ventricular pacing rate. Thus, a ventricular pacing rate close to the mean ventricular rate during control consistently reduced the ventricular variability. Although pacing at an increased ventricular standby rate reduces variability at rest, the optimal solution would likely be an adaptive rate algorithm that changes the ventricular standby rate as the mean intrinsic rate varies.
Holter Recordings with Continuous Marker Annotations: A New Tool in Pacemaker Diagnostics
Authors: NOWAK BERND , MIDDELDORF THOMAS , HOUSWORTH CRAIG M. , BRÜLS ANNETTE , LIEBRICH ANDREAS , ROSOCHA STEFAN , VOIGTLÄNDER THOMAS , HIMMRICH EWALD , MEYER JÜRGEN
Published: July 2006

Pacemakers provide marker annotations to facilitate the interpretation of pacemaker electrocardiograms (ECGs) and can be used in cases of suspected pacemaker malfunction or to understand pacemaker behavior. Due to the need for a programmer, only short‐term evaluations are possible. We evaluated a prototype Telemetry Data Logger (TDL) designed to continuously transfer markers from the pacemaker to a conventional Holter recorder. A miniaturized telemetry receiving coil was attached to patient's skin above the pacemaker, which was programmed to transmit markers continuously. The TDL, which receives and converts markers into eight positive and eight negative deflections, ranging from ‐2.5 to +2.5 mV in amplitude, was connected to one channel of a conventional Holter recorder (Tracker 2). We performed 20 Holters in 13 patients who had implanted VDDB or DDDR devices from the same manufacturer and evaluated three versions of software. Marker transmission was possible in all patients, producing Holter ECGs with complete marker annotations. Artifacts occurred < 4 % of the time. A 50‐ms rectangular pulse was optimal for marker interpretation. The device, which was easy to use and well accepted by the patients, assisted in the diagnosis of inappropriate pacemaker programming, even when the surface ECG seemed to show regular pacemaker function. In the presence of low quality surface ECGs, marker annotations allowed the assessment of pacemaker function. The capability to annotate the onset of special algorithms, like tachycardia termination algorithms or mode switching, facilitates interpretation of pacemaker behavior, enabling a reliable assessment of the appropriateness of such algorithms. Conclusion: The TDL effectively enables pacemaker markers to be inscribed onto a conventional Holter recording, facilitating the interpretation of pacemaker ECGs and the diagnosis of inappropriate pacemaker programming even when not discernible from the surface ECG alone.