bluuebunny/crossref_metadata_2025 huggingface dataset:
Can Early Timed Internal Atrial Defibrillation Shocks Reduce the Atrial Defibrillation Threshold?
Authors: FOTUHI PARWIS C. , COOPER RANDOLPH A.S. , SREENAN CATHERINE M. , ROLLINS DENNIS L. , SMITH WILLIAM M. , IDEKER RAYMOND E.
Published: July 2006

The defibrillation threshold is markedly reduced very early following the initiation of ventricular fibrillation. The purpose of this study was to determine if the same finding holds true for atrial defibrillation. Sustained, reproducible AF was induced with programmed atrial pacing using acetyl‐β‐methylcholine chloride (40–640 μL/min) in six adult sheep (heart weight 245–300 g). Seven timing intervals (125 ms, 200 ms, 1 s, 3 s, 10 s, 30 s, and 5 min after AF induction) and two lead configurations: (1) RA as cathode and CS as anode; and (2) RA as cathode and RV apex as anode were tested. Single capacitor biphasic waveforms (3/1 ms) were delivered and atrial defibrillation thresholds (ADFTs) were determined in random order. No significant differences in leading edge voltage and total energy were detected for the RA‐CS configuration for the seven timing intervals. For the RA‐RV configuration, a significant difference was detected comparing the voltage for 125 ms to the 5‐minute timing interval. For all times except 125 ms, the RA‐RV threshold was significantly higher than the RA‐CS level. In contrast to ventricular defibrillation, the ADFT does not change significantly within the first 5 minutes after the initiation of AF for the RA‐CS configuration. However, if the shock is given very early (125 ms after AF induction) with the RA‐RV configuration, the ADFT is lowered almost to the RA‐CS level.
Defibrillation Thresholds are Increased by Right‐Sided Implantation of Totally Transvenous Implantable Cardioverter Defibrillators
Authors: FRIEDMAN PAUL A. , RASMUSSEN MARY JANE , GRICE SUELLEN , TRUSTY JANE , GLIKSON MICHAEL , STANTON MARSHALL S.
Published: July 2006

Whether an ICD is placed via a left‐ or right‐sided approach depends on venous access, the presence of a preexisting pacemaker, and other factors. Since the DFT is affected by lead position, which in turn is determined in part by the side of access, right‐sided venous access could adversely affect DFTs. Furthermore, right‐sided active can placement directs electric current toward the right hemithorax, which could further increase DFTs. This study sought to determine whether DFTs were increased by right‐sided vascular access, and whether active can technology was beneficial or detrimental with right‐sided ICD placement. Stepdown to failure DFTs were found in 290 patients receiving transvenous systems at the time of initial ICD implantation. Of these, 271 (93%) received left‐sided systems and 19 (7%) received right‐sided systems. The mean DFT in systems placed via left‐sided vascular access was 11.3 ± 5.3 J versus 17.0 ± 4.9 J for right‐sided implantation (P < 0.0001); right‐sided DFTs were elevated for both active can and cold can systems. Right‐sided active can devices had a lower DFT than right‐sided cold can systems (15 ± 4.1 J vs 19 ± 4.8 J, P = 0.05). The right‐sided implantation of implantable defibrillators results in significantly higher DFTs than the left‐sided approach. This may be due to the less favorable distribution of the defibrillating field relative to the myocardium with the devices on the right. When right‐sided implantation is clinically mandated, active can devices result in lower thresholds and should be used.
Permanent Pacing in Patients with Univentricular Heart
Authors: WARFIELD DAVID A. , HAYES DAVID L. , HYBERGER LINDA K. , WARNES CAROLE A. , DANIELSON GORDON K.
Published: July 2006

Patients with one of several varieties of malformation designated as “univentricular hearts” may be especially challenging when permanent pacing is required. Our objective was to review our experience in this subset of patients that had undergone permanent pacing and thus determine the optimal approach. A retrospective chart review was done of 32 patients with some variety of “univentricular” malformation who had required permanent pacing at our institution. Although technically challenging, permanent pacing in this group of patients can be successful through several approaches. The various approaches, as well as consideration of the differences that exist between patients undergoing septation and those undergoing a Fontan procedure are discussed. Although long‐term permanent pacing is possible in this group of patients, before pacing begins, a thorough understanding of the anatomy and prior surgical procedures is necessary. Use of a combined atrial transvenous and ventricular epicardial pacing system may work well for some patients. With the development of newer and more reliable coronary sinus leads, dual chamber transvenous pacing with ventricular stimulation via the coronary sinus could become the approach of choice in some patients with “univentricular hearts.”
A Comparison of Ventricular Function During High Right Ventricular Septal and Apical Pacing after His‐Bundle Ablation for Refractory Atrial Fibrillation
Authors: MERA FERNANDO , DeLURGIO DAVID B. , PATTERSON RANDOLPH E. , MERLINO JOHN D. , WADE MARGARET E. , LEÓN ANGEL R.
Published: July 2006

This study compares LV performance during high right ventricular septal (RVS) and apical (RVA) pacing in patients with LV dysfunction who underwent His‐bundle ablation for chronic AF. We inserted a passive fixation pacing electrode into the RVA and an active fixation electrode in the RVS. A dual chamber, rate responsive pulse generator stimulated the RVA through the ventricular port and the RVS via the atrial port. Patients were randomized to initial RVA (VVIR) or RVS (AAIR) pacing for 2 months. The pacing site was reversed during the next 2 months. At the 2 and 4 month follow‐up visit, each patient underwent a transthoracic echocardiographical study and a rest/exercise first pass radionuclide ventriculogram. We studied nine men and three women (mean age of 68 ± 7 years) with congestive heart failure functional Class (NYHA Classification): I (3 patients), II (7 patients), and III (2 patients). The QRS duration was shorter during RVS stimulation (158 ± 10vs 170 ± 11 ms, P < 0.001). Chronic capture threshold and lead impedance did not significantly differ. LV fractional shortening improved during RVS pacing (0.31 ± 0.05 vs 0.26 ± 0.07, P < 0.01). RVS activation increased the resting first pass LV ejection fraction (0.51 ± 0.14 vs 0.43 ± 0.10, P < 0.01). No significant difference was observed during RVS and RVA pacing in the exercise time (5.6 ± 3.2 vs 5.4 ± 3.1, P = 0.6) or the exercise first pass LV ejection fraction (0.58 ± 0.15 vs 0.55 ± 0.16, P = 0.2). The relative changes in QRS duration and LV ejection fraction at both pacing sites showed a significant correlation (P < 0.01). We conclude that RVS pacing produces shorter QRS duration and better chronic LV function than RVA pacing in patients with mild to moderate LV dysfunction and chronic AF after His‐bundle ablation.
Pacing and ICD Therapy in Germany (West and East) Before and After Reunification in 1989
Authors: SPITZER STEFAN G.
Published: July 2006

In 1989 the two German countries, FRG and GDR, were reunited after 50 years of political separation. During this time, these countries underwent independent, and in parts quite different, developments. While the reunification has had less effect on the overall situation in the Western part of the country, the Eastern part has experienced considerable changes, including the health service. In the field of pacing and ICD therapy, this study finds that 8 years after the reunification, the German federal states of both parts of the country have converged in the field of pacing and ICD therapy.
Asymptomatic Form of Brugada Syndrome
Authors: TAKENAKA SHIHO , EMORI TETSUROU , KOYAMA SHIHO , MORITA HIROSHI , FUKUSHIMA KENGO , OHE TOHRU
Published: July 2006

We describe a patient with the asymptomatic form of Brugada syndrome. His electrographical, electropharmacological, and electrophysiological characteristics were similar to those reported in patients with the symptomatic form of Brugada syndrome. We believe that he has the same arrhythmogenic substrate as that of patients with Brugada syndrome. The fact that he had no episode of spontaneous ventricular fibrillation might be explained by his absence of the triggering factors.
Brugada‐Like Electrocardiographic Pattern in a Patient With a Mediastinal Tumor
Authors: TARÍN NIEVES , FARRÉ JERÓNIMO , RUBIO JOSÉ MANUEL , TUÑÓN JOSÉ , CASTRO‐DORTICÓS JORGE
Published: July 2006

We report on a patient with a mediastinal tumor and electrocardiographic findings similar to those described in the Brugada syndrome. This peculiar ECG pattern disappeared after tumor removal, thus suggesting it was probably caused by compression of the right ventricular outflow tract by the mass.
Peripheral Pulmonary Migration of a Retained Pacemaker Lead
Authors: BÕHM ÁDÁM , KOMÁROMY KATALIN , PINTÉR ARNOLD , PRÉDA ISTVÁN
Published: July 2006

We report a case of lead migration into the right middle pulmonary lobe. The migrated electrode reached the pleura and produced severe pleural symptoms. Due to the symptoms, surgical removal of the retained lead was required.
Value of Magnetocardiographic QRST Integral Maps in the Identification of Patients at Risk of Ventricular Arrhythmias
Authors: HREN ROK , STEINHOFF UWE , GESSNER CHRISTOF , ENDT PETER , GOEDDE PETER , AGRAWAL RAHUL , OEFF MICHAEL , LUX ROBERT L. , TRAHMS LUTZ
Published: July 2006

It has been shown that regional ventricular repolarization properties can be reflected in body surface distributions of electrocardiographic QRST deflection areas (integrals). We hypothesize that these properties can be reflected also in the magnetocardiographic QRST areas and that this may be useful for predicting vulnerability to ventricular tachyarrhythmias. Magnetic field maps were obtained during sinus rhythm from 49 leads above the anterior chest in 22 healthy (asymptomatic) control subjects (group A) and in 29 patients with ventricular arrhythmias (group B). In each subject, the QRST deflection area was calculated for each lead and displayed as an integral map. The mean value of maximum was significantly larger in the control group A than in the patient group B (1,626 ± 694 pTms vs 582 ± 547 pTms, P < 0.0001). To quantitatively assess intragroup variability in the control group A and intergroup variability of the control and patient groups, we used the correlation coefficient r and covariance σ. These indices showed significantly less intragroup than intergroup variation (e.g., in terms of σ, 28.0 · 10−6± 12.3 · 10−6 vs 3.4 · 10−6± 12.5 · 10−6, P < 0.0001). Each QRST integral map was also represented as a weighted sum of 24 basis functions (eigenvectors) by means of Karhunen‐Loeve transformation to calculate the contribution of the nondipolar eigenvectors (all eigenvectors beyond the third). This percentage nondipolar content of magnetocardiographic QRST integral maps was significantly higher in the patient group B than in the control group A (13.0%± 9.1% vs 2.6%± 2.0%, P < 0.0001). Discriminations between control subjects and patients with ventricular arrhythmias based on magnitude of the maximum, covariance σ, and nondipolar content were 90.2%, 90.2%, and 86.3% accurate, with a sensitivity of 89.7%, 93.1%, and 75.9%, and a specificity of 90.9%, 86.4%, and 100%. We have shown that magnitude of the maximum and indices of variability and nondipolarity of the magnetocardiographic QRST integral maps may predict arrhythmia vulnerability. This finding is in agreement with earlier studies that used body surface potential mapping and suggests that magnetic field mapping may also be a useful diagnostic tool for risk analysis.
Quality‐of‐Life Six Months After CABG Surgery in Patients Randomized to ICD Versus No ICD Therapy: Findings from the CABG Patch Trial
Authors: NAMEROW PEARILA B. , FIRTH BEVERLY R. , HEYWOOD GEOFFREY M. , WINDLE JOHN R. , PARIDES MICHAEL K. ,   CABG PATCH TRIAL INVESTIGATORS AND COORDINATORS
Published: July 2006

ICDs can affect a patient's perceived quality‐of‐life (QOL). This article describes the QOL in patients who participated in The CABG Patch Trial. This trial evaluated the potential benefit of empiric ICD implantation in patients with an increased risk of arrhythmic cardiac death as determined by reduced ejection fraction (< 0.36) and an abnormal signal‐averaged ECG. Patients were randomized to control (no ICD) or treatment (ICD) limbs. QOL was measured using the SF‐36 and other measures among 490 (68%) of 719 patients available at 6‐month follow‐up. Analysis was performed on 228 control patients (those without ICDs) and 262 patients with ICDs. Results: Six months after having CABG surgery, patients in the ICD group had lower levels of psychological well‐being than those in the control group. In addition, compared to controls, patients whose ICDs had delivered therapy reported feeling less healthy, had reduced physical and emotional role functioning, and had lower levels of psychological well‐being. Conclusion: Strategies aimed at easing patients' adjustment to ICDs should be developed and tested for efficacy in the setting of ICD prophylaxis.
Spectrotemporal Mapping of High‐Resolution ECGs in Experimental Myocardial Infarction:Comparison with Time‐Domain Analysis and Epicardial Electrograms
Authors: HOFMANN MONIKA , GOEDEL‐MEINEN LISELOTTE , LEIPERT HELGA , SCHAD HUBERT , HEIMISCH WERNER , MENDLER NIKOLAUS , SCHÖMIG ALBERT
Published: July 2006

Domain Analysis and Epicardial Electrograms. The study was undertaken to evaluate the relationship of signal‐averaged ECG (SA‐ECG) readings in the frequency domain (STM) and epicardial electrograms (EE) recorded before and after acute myocardial infarction (AMI) in pigs and to compare the changes with findings in timedomain analysis (TDA). In 20 pigs the left anterior descending artery (LAD) was ligated. Prior to ligation, a SA‐ECG was recorded (method of Simson) and bipolar electrodes were used to register EE in the areas supplied by the LAD and the circumflex artery (CIRC). Five minutes after LAD ligation, all measurements were repeated. Time‐domain parameters were QRS duration (QRS D) and the duration of the signal below 30 μV (LAS 30). Beginning at a point of 20 ms before the QRS end, the frequency spectra (0–200 Hz) of 25 segments of 80‐ms duration at the QRS end were analyzed. The volumes below the 25 curves were analyzed separately for 0–50 Hz, 51–100 Hz, 101–150 Hz, and 151–200 Hz. After AMI, five pigs died within 7 minutes. In 15 pigs, QRS D as well as LAS 30 lengthened significantly (P < 0.05; P < 0.001). Spectrotemporal mapping (STM) showed a significant decrease of the frequencies above 50 Hz (51–200 Hz) in the entire group and in the animals with late potentials (P < 0.05). EE of the LAD area were significantly prolonged (P < 0.01); this did not correlate with the changes in STM parameters. In pigs acute myocardial infarction causes a shift towards lower frequencies in the STM which most likely reflects the slowed depolarisation in the ischemic area.
Usefulness of Echocardiography to Predict Inappropriate Atrial Sensing in Single‐Lead VDD Pacing
Authors: DE COCK CAREL C. , VAN CAMPEN LINDA C.M.C. , HUYGENS JEROEN , KAMP OTTO , VISSER CEES A.
Published: July 2006

Reliable atrial sensing is the prerequisite for restoration of atrioventricular synchrony in patients with single‐lead VDD pacing systems. To determine echocardiographic variables associated with inappropriate atrial sensing, 21 consecutive patients with symptomatic second‐ or third‐degree AV block and normal sinus node function were studied. Prior to implantation echocardiographic measurements of end‐systolic and end‐diastolic dimensions and volumes of the right atrium and right ventricle were performed. All patients underwent implantation of a Medtronic Thera VDD(d) pacemaker with a bipolar Medtronic Capsure electrode. A minimal amplitude of the unfiltered atrial electrocardiogram of ≥ 0.5 mV was required for permanent lead position and the atrial sensitivity was programmed below the lowest recorded value. Appropriate atrial sensing (atrial triggered ventricular paced complexes/total number of ventricular paced complexes) was assessed during 24‐hour Holter monitoring and treadmill exercise testing 3 to 6 weeks after implantation. Inappropriate atrial sensing (< 95% correct atrial synchronization during Holter registration and/or < 97.5% during exercise testing) was present in nine patients. Right atrial volumes and the right ventricular end‐diastolic volume was significantly higher, as compared to patients without inappropriate sensing (12 patients). The right atrial and diastolic volumes had the highest correlation with correct atrial sensing r = 0.83, P < 0.0001). Using a postdefined cut‐off value of ≥ 80 mL for the end‐diastolic right atrial volume, sensitivity and specificity for inappropriate sensing was 100% and 92%, respectively. These findings show that preimplant echocardiography can identify patients with inappropriate sensing during VDD pacing, in whom DDD pacing should be considered.
Intravascular Extraction of Problematic or Infected Permanent Pacemaker Leads: 1994–1996
Authors: BYRD CHARLES L. , WILKOFF BRUCE L. , LOVE CHARLES J. , SELLERS T. DUNCAN , TURK KYONG T. , REEVES RUSSELL , YOUNG RAYMOND , CREVEY BARRY , KUTALEK STEVEN P. , FREEDMAN ROGER , FRIEDMAN RICHARD , TRANTHAM JOEY , WATTS MICHAEL , SCHUTZMAN JOHN , OREN JESS , WILSON JOHN , GOLD FRANK , FEARNOT NEAL E. , VAN ZANDT HEIDI J. ,   U.S. EXTRACTION DATABASE, MED INSTITUTE
Published: July 2006

Of the 400,000–500,000 permanent pacemaker leads implanted worldwide each year, around 10% may eventually fail or become infected, becoming potential candidates for removal. Intravascular techniques for removing problematic or infected leads evolved over a 5‐year period (1989–1993). This article analyzes results from January 1994 through April 1996, a period during which techniques were fairly stable. Extraction of 3,540 leads from 2,338 patients was attempted at 226 centers. Indications were: infection (27%), nonfunctional or incompatible leads (25%), Accufix® or Encor® leads (46%), or other causes (2%). Patients were 64 ± 17 years of age (range 5–96); 59% were men, 41% women. Leads were implanted 47 ± 41 months (maximum 26 years), in the atrium (53%), ventricle (46%), or SVC (1%). Extraction was attempted via the implant vein using locking stylets and dilator sheaths, and/or transfemorally using snares, retrieval baskets, and sheaths. Complete removal was achieved for 93% of leads, partial for 5%, and 2% were not removed. Risk of incomplete or failed extraction increased with implant duration (P < 0.0001), less experienced physicians (P < 0.0001), ventricular leads (P < 0.005), noninfected patients (P < 0.0005), and younger patients (P < 0.0001). Major complications were reported for 1.4% of patients (< 1% at centers with > 300 cases), minor for 1.7%. Risk of complications increased with number of leads removed (P < 0.005) and with less experienced physicians (P < 0.005); risk of major complications was higher for women (P < 0.01). Given physician experience, appropriate precautions, and appropriate patient selection, contemporary lead removal techniques allow success with low complication rates.
Altered Cardiac Histology Following Apical Right Ventricular Pacing in Patients with Congenital Atrioventricular Block
Authors: KARPAWICH PETER P. , RABAH RAJA , HAAS JOEL E.
Published: July 2006

Previous studies have demonstrated that right ventricular apical pacing inherently alters ventricular contraction, regional blood flow, wall stress, and predisposes to diminished function. However, histological consequences of chronic apical pacing potentially contributing to the observed ventricular dysfunction remain conjectural. Previous canine studies have demonstrated histopathological cellular abnormalities with apically initiated ventricular pacing that may result in the observed diminished ventricular function. To determine if comparable adverse changes also occur in the clinical setting, 16 endomyocardial biopsies were obtained from 14 age‐matched patients with congenital complete atrioventricular block (CCAVB) and otherwise normal anatomy, divided into two groups: eight biopsies (median patient age 15.5 years) from patients prior to pacemaker implant and another eight biopsies (median patient age 16 years) from patients following 3–12 years (median 5.5) of chronic ventricular pacing. In one patient, biopsy samples were obtained before and after pacing. Results demonstrated a significant (P < 0.05) increase in histopathological alterations among the patient biopsy samples following pacing, consisting of myofiber size variation, fibrosis, fat deposition, sclerosis, and mitochondrial morphological changes. These findings indicate that chronic apical right heart ventricular pacing may adversely alter myocellular growth, epecially among the young, on the cellular and subcellular level, potentially contributing to the diminished function observed clincially.
Effects of Adenosine on Local Stimulus‐Response Latency and Induction of Atrial Fibrillation by Premature Stimuli
Authors: CORBISIERO RAFFAELE , KABELL GLENN , COOK JAMES R. , FITZGERALD THOMAS F. , KIRCHHOFFER JAMES B.
Published: July 2006

Premature atrial stimuli delivered during the relative refractory or “vulnerable” period exhibit increased local stimulus‐response latency and may occasionally induce atrial arrhythmias. The use of adenosine to treat supraventricular tachycardias may also provoke atrial arrhythmias. In this study we investigated the effects of adenosine on the latency of premature complexes in relation to repolarization and induction of atrial arrhythmias in 14 patients without structural heart disease. A monophasic action potential catheter was used for recording in the right atrium and introducing premature stimuli (S2) at twice diastolic threshold after eight paced (S1) complexes. At short coupling intervals, S2 latency increased relative to S1 latency. S2 was delivered repeatedly at a fixed coupling interval (producing maximal local response latency) and adenosine (6 mg) was given intravenously. Adenosine decreased S2 latency significantly (23 ± 5 to 11 ± 3 ms, P < 0.01), to values similar to S1 latency. However, despite the decrease in S2 latency, the combination of adenosine and S2 more often resulted in transient atrial arrhythmias (11 of 14 patients vs 2 of 14 patients without adenosine, P < 0.05). Adenosine had no effect on S1 latency (9 ± 2 vs 9 ± 2 ms) but decreased monophasic action potential duration from 202 ± 37 to 158 ± 38 ms (P < 0.01). Adenosine was also given to 10 patients S2 introduced at a coupling interval 40–50 ms less than the baseline effective refractory period. This resulted in a decrease in atrial refractoriness and capture of S2 in all cases. Latency for S2 was significantly greater than S1 latency (21 ± 12 vs 9 ± 2 ms, P < 0.01) and transient atrial arrhythmias were induced in 9 of 10 patients. We conclude that for a given S2 coupling interval, adenosine decreases local stimulus–response latency but increases atrial vulnerability to transient atrial arrhythmias. Decreased latency may be related to a shift in the zone of relative refractoriness associated with an adenosine‐mediated decrease in monophasic action potential duration. Induction of atrial arrhythmias in the presence of adenosine occurs independently of increased latency and is therefore not dependent on S2 falling within the relative refractory period at the site of stimulation.
Comparison of Formulae for Heart Rate Correction of QT Interval in Exercise Electrocardiograms
Authors: AYTEMIR KUDRET , MAAROUF NIDAL , GALLAGHER MARK M. , YAP YEE GUAN , WAKTARE JOHAN E.P. , MALIK MAREK
Published: July 2006

The study investigated the differences in five different formulae for heart rate correction of the QT interval in serial electrocardiograms recorded in healthy subjects subjected to graded exercise. Twenty‐one healthy subjects (aged 37 ± 10 years, 15 male) were subjected to graded physical exercise on a braked bicycle ergometer until the heart rate reached 120 beats/min. Digital electrocardiograms (ECG) were recorded on baseline and every 30 seconds during the exercise. In each ECG, heart rate and QT interval were measured automatically (QT Guard package, Marquette Medical Systems, Milwaukee, WI, USA). Bazett, Fridericia, Hodges, Framingham, and nomogram formulae were used to obtain QTc interval values for each ECG. For each formula, the slope of the regression line between RR and QTc values was obtained in each subject. The mean values of the slopes were tested by a one‐sample t‐test and the comparison of the baseline and peak exercise QTc values was performed using paired t‐test. Bazett, Hodges, and nomogram formulae led to significant prolongation of QTc intervals with exercise, while the Framingham formula led to significant shortening of QTc intervals with exercise. The differences obtained with the Fridericia formula were not statistically significant. The study shows that the practical meaning of QTc interval measurements depends on the correction formula used. In studies investigating repolarization changes (e.g., due to a new drug), the use of an ad‐hoc selected heart rate correction formula is highly inappropriate because it may bias the results in either direction.
Anomalous “VVI” Pacing of a Dual Chamber Pacemaker When Programmed in DDI(R) Mode
Authors: MASINI MICHELE , DIANDA RENZO , CORTIGIANI LAURO , NANNINI EUGENIO
Published: July 2006

We describe the case of a dual chamber rate responsive pacemaker (Relay, model 294‐03, Intermedics, Angleton, TX, USA) implanted in a 68‐year‐old male for sick sinus syndrome, which was not working properly when programmed in the DDIR mode, thus determining occasionally a sort of “VVI” pacing. However, the pacemaker performed well when programmed in the DDDR mode. We discovered that this was not a malfunction of a single device but rather a general behavior of this family of Intermedics dual chamber pacemakers (also not rate responsive), caused by a software problem.
Association Between Nonreentrant Supraventricular Tachycardia and Atrioventricular Node Reentrant Tachycardia: A Presentation of Dual AV Node Physiology
Authors: MAURY PHILIPPE , ZIMMERMANN MARC , METZGER JACQUES , CREVOISIER JEAN‐LUC , ADAMEC RICHARD
Published: July 2006

Persistent simultaneous conduction of P waves over a fast and a slow nodal pathway defines the nonreentrant type of supraventricular tachycardia, usually not associated with reciprocating movements. We report a unique association between this uncommon tachycardia and a usual AV nodal reentrant tachycardia, made possible by the existence of three different nodal pathways.
Twiddler's Syndrome with Transvenous Defibrillators in the Pectoral Region
Authors: SALIBA BASSAM C. , GHANTOUS ANDRE E. , SCHOENFELD MARK H. , MARIEB MARK A.
Published: July 2006

Advances in technology have enabled the implantation of defibrillators in the pectoral region. Complications encountered with pacemakers may also be observed with defibrillators. We describe two cases of twiddler's syndrome in patients with defibrillators implanted subcutaneously in the left pectoral region.
Inverse Relation of Body‐Surface Activation‐Recovery Interval and Recovery Time to Activation Time in Normal Subjects: Stronger Correlation and More Heterogeneous Distribution in Activation‐Recovery Interval Than in Recovery Time
Authors: IWATA KAZUKI , HIRAI MAKOTO , YOSHIDA YUKIHIKO , IINO SHIGEO , KONDO TAKAHISA , SHIMIZU ATSUYA , TERAZAWA MASAYUKI , AKAHOSHI MAKOTO , INDEN YASUYA , SUGINO MIKIO , TSUDA MAKOTO , TOMITA YASUSHI , SAITO HIDEHIKO
Published: July 2006

The activation‐recovery interval (ARI), measured directly from the myocardium, has shown a good correlation with the action potential duration (APD) in experiments. APD has been reported to be inversely related to the activation time (AT). However, no studies have examined the correlation between the body‐surface ARI and AT in normal subjects. Fifty normal subjects (25 men and 25 women) were studied to elucidate the relationship between the body‐surface ARI and AT. The body‐surface AT was defined as the duration between the QRS onset and the minimum dV/dt of the QRS wave, and ARI as the interval between the minimum dV/dt of the QRS wave and the maximum dV/dt of the T wave in each lead of an 87 unipolar lead system. We also measured the recovery time (RT) defined as the duration between the QRS onset and the maximum dV/dt of the T wave. ARI was inversely correlated with AT (r = ‐0.73). RT was also inversely correlated with AT (r = ‐0.61), however, RT had a less heterogeneous distribution than ARI (148 ms vs 159 ms). There were no differences between male and female subjects in the relation between ARI and RT or in the body‐surface distribution of ARI and RT. These findings suggest that the body‐surface ARI may reflect recovery properties over the cardiac surface and that APD may distribute inhomogsneously over the human cardiac surface with a longer RT over an area with a shorter AT. ARI calculated from body‐surface ECG may be a useful noninvasive and repeatedly measurable estimate of APD.
Importance of the Site of Ventricular Tachycardia Origin on Left Ventricular Hemodynamics in Humans
Authors: KOLETTIS THEOFILOS M. , KYRIAKIDES ZENON S. , POPOV TODOR , MESISKLI THEONI , PAPALAMBROU ANASTASIOS , KREMASTINOS DIMITRIOS TH.
Published: July 2006

Experimental animal data have indicated that the site of ventricular tachycardia origin and, hence, the degree of asynchronous contraction, may influence the hemodynamic tolerance during sustained ventricular tachycardia. However, data in man are scarce. We studied patients with preserved left ventricular function and absence of significant coronary artery disease. Ventricular tachycardia was simulated with rapid pacing (at 120 and 150 beats/min), performed randomly, from the right ventricular apex or the right ventricular outflow tract. Following pacing from one site, it was repeated from the alternate site. Compared to outflow tract pacing, QRS duration was significantly longer during rapid pacing from the apex. Left ventricular pressure was recorded using a micromanometer‐tipped catheter. During sinus rhythm, peak systolic pressure was 142 ± 14 mmHg: at 120 beats/min, it decreased to 109 ± 12 mmHg during pacing from the apex and to 127 ± 21 mmHg during pacing from the outflow tract (P = 0.008). This difference diminished at 150 beats/min (101 ± 16 mmHg vs 112 ± 16 mmHg, respectively, P = 0.21). During sinus rhythm end‐diastolic pressure was 13 ± 1 mmHg, which did not change significantly during pacing at 120 beats/min. During pacing at 150 beats/min, end‐diastolic pressure increased to 21 ± 3 mmHg during pacing from the apex and to 16 ± 2 mmHg during pacing from the outflow tract (P = 0.005). Changes in first derivative of pressure and in isovolumic relaxation time constant were comparable during pacing from the two sites. Thus, it seems that tachycardias originating from the right ventricular outflow tract result in more favorable left ventricular hemodynamics, compared to those from the right ventricular apex
Acute Hemodynamic Effects of Alternate and Combined Site Pacing in Patients after Cardiac Surgery
Authors: BUCKINGHAM THOMAS A. , CANDINAS RETO , DURU FIRAT , FAGOTTO ESTHER , SCHÖNBECK MARIETTE , AMANN F. WOLFGANG , TURINA MARKO , SCHMID EDITH R.
Published: July 2006

We hypothesized that pacing at sites other them the right ventricular (RV) apex or at two or more ventricular sites would activate the myocardium more rapidly and improve cardiac function in patients undergoing coronary revascularization or aortic valve replacement. Epicardial electrodes were placed on the right atrium (A), RV paraseptal area close to the RV apex (B), RV outflow tract (C), LV apex (D), in patients undergoing bypass surgery. At constant rate and AV delay, we measured CO during A pacing, DV1 pacing at B, C, D, and various combinations of sites in random order in ten patients with EF > 50% and 27patients with EF ≤ 50%. When pacing at two sites, we made one electrode a cathode and one an anode and noted two distinct thresholds by careful observation of the 12‐lead ECG. There were no significant differences in CO, systemic vascular resistance, systolic, or mean arterial pressure. Significant differences were noted in QRS duration, which increased progressively going from AAI to 3‐site, 2‐site, and single site pacing (P < 0.05 each comparison). Thus: (1) QRS duration correlated inversely with the number of ventricular sites paced; (2) despite this, CO did not improve irrespective of baseline EF; (3) multisite pacing produced multiple distinct thresholds which appeared to be related to the number of sites paced, and (4) unique ECG patterns confirmed multisite pacing.
Significant Differences in Charge Times Among Currently Available Implantable Cardioverter Defibrillators
Authors: MANN DAVID E. , KELLY PATRICIA A. , ROBERTSON ALASTAIR D. , OTTO LYNN , REITER MICHAEL J.
Published: July 2006

Capacitor charging accounts for most of the delay between arrhythmia detection and therapy delivery in ICDs. Long capacitor charge times may increase the risk of syncope in patients with poorly tolerated arrhythmias. To determine if there are clinically important differences in charge time among currently available devices, we analyzed charge times at various delivered energy levels in three manufacturers’devices: Medtronic, CPI, and Ventritex, Charge times were measured for shocks delivered for spontaneous or induced arrhythmias occurring from time of implant to 4 months after implant. A total of 343 shocks were assessed in 63 patients with ICDs: 16 Medtronic (Microfewel II, model 7223Cx). 14 CPI (Mini II, model 1762), and 33 Ventritex (Cadet and Contour, models V‐115 and V‐145). The curves of the relationship between charge time and delivered energy for the three types of devices were significantly different, with Medtronic charge times shorter than CPI or Ventritex (P < 0.0001), and CPI charge times shorter than Ventritex (P ‐ 0.002). The difference in mean charge times between the Ventritex and Medtronic devices ranged from 1.7 seconds at a delivered energy of 10 ± 2.5 J to 8,0 seconds at a delivered energy of 30 ± 2.5 J. Thus, clinically important differences in charge time exist among the three types of defibrillators studied. These results should be considered in selecting an ICD for patients with poorly tolerated arrhythmias.
Health‐Related Quality‐of‐Life Assessment of Patients with Life‐Threatening Ventricular Arrhythmias
Authors: HERBST JEFFREY H. , GOODMAN MARK , FELDSTEIN STANLEY , REILLY JOSEPH M.
Published: July 2006

The purpose of this study was to determine whether treatments for life‐threatening ventricular arrhythmias are associated with quality‐of‐life (QOL) and psychological distress. Multidimensional measures of QOL and psychological distress were used to cross‐sectionally compare patients with ICDs to patients treated with antiarrhythmic drugs and patients without serious cardiac conditions. The sample consisted of 157 patients: 35 patients treated with antiarrhythmic medication only, 24 patients treated with ICD only, 25 patients treated with ICD and antiarrhythmic medication, and 73 controls. Patients completed the Medical Outcomes Study SF‐36 health survey, the Brief Symptom Inventory, and background questionnaires. There were no significant differences in self‐reported QOL and psychological distress between patients with or without ICD, and the occurrence of defibrillator shocks was unrelated to QOL and psychological distress. However, patients treated with antiarrhythmic drugs reported greater QOL impairment in physical functioning, vitality, emotional role limitations, and sleep, as well as greater psychological distress than patients not treated with antiarrhythmics. These limitations may be attributed to adverse effects arising from antiarrhythmic pharmacotherapy. Results of the present investigation suggest that QOL and psychological distress are maintained among ICD patients, whereas treatment with antiarrhythmic drugs are associated with a diminished QOL and greater psychological distress. These findings may assist cardiologists to select the optimal treatment for life‐threatening ventricular arrhythmias that minimizes disturbances in health‐related QOL and psychological distress and increases patient compliance.
Electrophysiological Performance of a Bipolar Membrane‐Coated Titanium Nitride Electrode: A Randomized Comparison of Steroid and Nonsteroid Lead Designs
Authors: WIEGAND U.K.H. , ZHDANOV A. , STAMMWITZ E. , CROZIER I. , CLAESSENS R.J.J. , MEIER J. , BOS R.J. , BODE F. , POTRATZ J.
Published: July 2006

The aim of this multicenter study was to investigate the performance of a new cardiac pacemaker lead with a titanium nitride cathode coated with a copolymer membrane. In particular, the electrophvsiological effect of steroid dissolved in this ion‐exchange membrane was evaluated by randomized comparison. Ninety five patients were randomized either to the 1450 T (n = 51) or the 1451 T ventricular lead (n = 45) and received telemeteral VVI(R) pacemakers with identical diagnostic features. Both leads were bipolar, were passively affixed, and had a porous titanium nitride tip with a surface area of 3.5 mm2. The only difference between the two electrodes was 13 μg of dexamethasone added to the 1450 Ts membrane coating. Voltage thresholds (VTH) at pulse durations of 0.25, 0.37, and 0.5 ms, lead impedance, and sensing thresholds were measured at discharge, 2 weeks, 1 month, 3 months, and 6 months after implantation. Mean amplitude and the slew rate from three telemetered intracardiac electrograms, clironaxie‐rheobase product, and minimum energy consumption were calculated. After a 6‐month follow‐up, mean voltage thresholds of 0.65 ± 0.20 V and 0.63 ± 0.34 were achieved for the 1450 T lead and 1451 Tlead, respectively. As a result, a VTH < 1.0 V was obtained in all patients with 1450 T electrodes and in 97.7% of patients with 1451 T leads after 6 months follow‐up. In both electrodes, stable VTH was reached 2 weeks after implantation, and no transient rise in threshold was observed. No differences were observed between the steroid and the nonsteroid group in respect to VTH, chronaxie‐rheobase product, minimum energy consumption, and potential amplitude and slew rate. In conclusion, safe and efficient pacing at low pulse amplitudes were achieved with both leads. The tip design, independently of the steroid additive, prevented any energy‐consuming increases in the voltage threshold.
The Utility of Pacemaker Evoked T Wave Amplitude for the Noninvasive Diagnosis of Cardiac Allograft Rejection
Authors: BAINBRIDGE A.D. , CAVE M. , NEWELL S. , DELANEY M. , PARAMESHWAR J. , LARGE S.R. , WALLWORK J. , GRACE A.A. , CAREY N.R. , SCHOFIELD P.M.
Published: July 2006

Previous work suggested that pacemaker evoked T wave amplitude (ETWA) may be a sensitive noninvasive marker of cardiac allograft rejection. A Topaz QT sensing rate responsive pacemaker (Vitatron Medical) was implanted at transplantation using epicardial ventricular leads in 45 recipients (35 males; median age 51 years, range 20‐63). The median duration of followup was 129 days (range 4‐327). The ETWA at a paced rate of 100 beats/min was measured daily during hospitalization and at each outpatient attendance (900 readings). Endomyocardial biopsies were at routine intervals or when otherwise clinically indicated (257 biopsies with concurrent ETWA data). There were 58 episodes of rejection ≥ grade 3a in 28 patients. The biopsies were classed as either no rejection (grade < 3a) or rejection requiring treatment (grade ≥ 3a). The median normalized ETWA was 100.8% (range 24.6‐239.7) without rejection and 89.9% (17.0 ‐189.7) with rejection (Mann‐Whitney U Test: P = 0.028). The performance of ETWA monitoring as a diagnostic test for the individual recipient was evaluated with exponentially weighted moving average quality control charts. For the diagnosis of all rejection episodes, ETWA monitoring had a sensitivity of 55%, a specificity of 62%, a positive predictive value of 30%, and negative predictive value of 83%, It is concluded that although analysis of pooled data showed a significant reduction in normalized ETWA with biopsy proven rejection, ETWA monitoring requires further refinement to improve sensitivity before it can be considered a clinically useful technique for the noninvasive diagnosis of cardiac allograft rejection in individual recipients.
Possible Involvement of Hypothyroidism as a Cause of Lithium‐Induced Sinus Node Dysfunction
Authors: NUMATA TETSUYA , ABE HARUHIKO , TERAO TAKESHI , NAKASHIMA YASUHIDE
Published: July 2006

Although several reports have stated that even therapeutic levels of lithium can induce sinus node dysfunction, the mechanism has not been fully elucidated. We present here two patients with sinus node dysfunction after long‐term lithium therapy. Following lithium discontinuation, sinus node function recovered completely. After resuming lithium, however, irreversible sinus node dysfunction recurred and a permanent pacemaker was implanted in one patient. The serum concentration of lithium was within therapeutic levels. Nevertheless, hypothyroidism was associated with the sinus node dysfunction in both patients. Thus, thyroid function may play an important role in sinus node dysfunction induced by lithium. (PACE 1999; 22[Pt. I]‐.954‐957) lithium, sinus node dysfunction, hypothyroidism, sick sinus syndrome
Removal of Infected Pacemaker Leads with Deep Hypothermic Circulatory Arrest and Open Surgical Exploration of the Superior Vena Cava and Innominate Veins
Authors: FELDBAUM* DAVID M. , BRODMAN RICHARD F. , FRAME ROSEMARY , CAMACHO MARGARITA T. , GROSS JAY , FERRICK KEVIN
Published: July 2006

Despite the use of transvenous methods for extraction of infected leads, failed attempts may result in retained lead fragments. Retained lead fragments may be a focus of continued infection leading to sepsis. We present two patients in which conversion from cardiopulmonary bypass to hypothermic circulatory arrest allowed direct visualization, using venotomies in the superior vena cava and innominate vein to achieve complete removal of retained pacemaker lead fragments. Use of venotomies in the extracardiac venous system is a technical addition to prior descriptions of lead extraction using deep hypothermia and circulatory arrest.
Complete Atrioventricular Block after Arsenic Trioxide Treatment in an Acute Promyelocytic Leukemic Patient
Authors: HUANG CHIEN‐HUA , CHEN WEN‐JONE , WU CHAU‐CHUNG , CHEN YAO‐CHANG , LEE YUAN‐TEH
Published: July 2006

A V block after arsenic trioxide (As2O3) treatment for refractory acute promyelocytic leukemia is very rare. In this patient, the block was at A‐H level and manifested with complete AV block and Wenckebach second‐degree type 3:2 block. The junctional recovery time during complete AV block did not significantly prolong after administration of more arsenic trioxide. The effect of heart block of arsenic trioxide seemed reversible after the discontinuation of arsenic trioxide and was not correlated to the leukemic status as observed in this patient.
Partial Rupture of the Tricuspid Valve after Extraction of Permanent Pacemaker Leads: Detection by Transesophageal Echocardiography
Authors: ASSAYAG PATRICK , THUAIRE CHRISTOPHE , BENAMER HAKIM , SEBBAH JOEL , LEPORT CATHERINE , BROCHET ERIC
Published: July 2006

Traumatic lesions of the tricuspid valve complicating pacemaker lead extractions appear to be rare. We report two cases of partial rupture of the tricuspid valve, following apparently uneventful extraction of permanent ventricular leads, resulting in severe regurgitation and. in one case, chronic heart failure. TEE was useful to identify the traumatic mechanism of tricuspid regurgitation (TR) and the extent of valvular lesions in these patients. Such etiology should be suspected, and TEE performed, in patients developing TR or heart failure late after lead extraction.
Lead Failure Due to the Subclavian Crush Syndrome in a Patient Implanted with Both Standard and Thin Bipolar Spiral Wound Leads
Authors: WEINER STANISLAV , PATEL JAGRUTI , JADONATH RAM L. , GOLDNER BRUCE G. , GROSS JAY N.
Published: July 2006

Subclavian crush syndrome is a well‐described cause of pacemaker lend failure resulting from an entrapment of a lead or leads between the clavicle and the first rib. A new thinner lead (Thin Linetm) was designed to minimize this complication. Our patient de veloped atrial and ventricular lead subclavian crush syndrome with both conventional and thin leads.
Extraction and Reimplantation of Defibrillation Leads Through a Thrombotic Subclavian Vein
Authors: LE FRANC PIERRE , KLUG DIDIER , JARWE MUSTAPHA , DELFAUT PHILIPPE , LACROIX DOMINIQUE , KOUAKAM CLAUDE , KACET SALEM
Published: July 2006

Venous thrombosis is one of the most frequently encountered obstacles when reintervening on endocardial leads. We report on two patients with a ventricular defibrillator requiring lead replacement in whom a subclavian vein thrombosis was documented prior to the intervention. We recanalized the vein and replaced the lead through the same path to preserve the venous access.
Migration of leafhoppers (Homoptera: Auchenorrhyncha) into a new polder
Authors: Schulz Carl A. , Meijer Jan
Published: July 2006

Auchenorrhyncha of a new polder were sampled by different kinds of traps in four stations in new habitats, one station on the salt marsh and one just outside the polder. In the latter stations 20 species of Auchenorrhyncha were caught in numbers that declined during the four year study. The proportion of macropters of the common Streptanus sordidus was highest in the largest catches. In the polder proper 392 specimens of 13 species were caught, all had moved at least 1500 m, but some could be traced to origins at greater distances. The number of immigrants also declined during the study. The distribution of the leafhoppers over the trapping stations suggests that leafhoppers, although sometimes transported over great distances, as a rule quickly fall out once they are airborne. Probably only one species had founded a resident population in the new polder at the end of the study.
The Lake Øvre Heimdalsvatn ‐ a subalpine freshwater ecosystem: Introduction
Authors: Vik Rolf
Published: July 2006

The interdisciplinary study of the lake ecosystem was carried out under the auspices of the International Biological Programme. The reasons for the choice of the lake and the personnel and institutions involved in the project are described. A brief description is given of the lake itself, its catchment area and its location, together with a short historical review of the development of the area and the degree of human influence.
The geology of the Øvre Heimdalen valley
Authors: Skjeseth Steinar , Kloster Asbjørn Elias
Published: July 2006

Øvre Heimdalsvatn is clearly influenced by the geological conditions, and the lake basin and catchment area are determined by the bedrock and the mountain structures. The distribution and characteristics of the loose deposits are decisive for the lake's water budget. The groundwater in the catchment area and the Quaternary deposits near the lake influence the amount and quality of the lake waters.
The vegetation of the Øvre Heimdalen valley
Authors: Østhagen Haavard , Egelie Kjell
Published: July 2006

The catchment area of Øvre Heimdalsvatn reaches from the upper half of the subalpine birch forest zone to the lowermost part of the high‐alpine subzone within the alpine zone. The units dominating the area include mountain birch forest, tall herb meadow, mire vegetation, bilberry heath, snowbed communities, chionophobous heath vegetation, and areas without a continuous vegetation layer. It is shown that the potential natural vegetation corresponds closely to the actual vegetation distribution.
The vertebrates of the Øvre Heimdalen valley
Authors: Lien Leif
Published: July 2006

The small mammals of the Øvre Heimdalen valley were assessed by snap‐trapping. Birds were surveyed in the shore zone of the lake. Numbers of domestic animals were collected from existing sources. These data are used in a discussion of the influence of the terrestrial fauna on the lake ecosystem. Aquatic production of food for terrestrial vertebrates, and the fertilizing effect of the terrestrial fauna are the main influences on the lake.