bluuebunny/crossref_metadata_2025 huggingface dataset:
Implantation Strategy of the Atrial Dipole Impacts Atrial Sensing Performance of Single Lead VDD Pacemakers
Authors: WIEGAND UWE K.H. , NOWAK BERND , REISP UDO , PEIFFER TORSTEN , BODE FRANK , POTRATZ JÜRGEN ,   THE SAPHIR MULTICENTER FOLLOW‐UP STUDY GROUP
Published: July 2003

WIEGAND, U.K.H., et al.: Implantation Strategy of the Atrial Dipole Impacts Atrial Sensing Perfor‐mance of Single Lead VDD Pacemakers. Intermittent atrial undersensing is observed in a considerable percentage of patients with single lead VDD pacemakers. Analyzing the 2‐year data of the Saphir Multicenter Follow‐Up Study, the authors investigated predictors for the occurrence of undersensing. The study included 194 patients with high degree AV block who received a VDD pacemaker system with an identical sensing amplifier. Placement strategy of the atrial dipole was left to the discretion of the implanting physician. At the final position, atrial potential amplitudes were measured during deep and shallow respiration. Atrial dipole position was determined by intraoperative fluoroscopy subdividing the right atrium in a high, mid, and low portion. Undersensing was defined by evidence of at least one not sensed P wave during Holter monitoring or exercise testing and by the presence of 0.1–0.2 mV amplitudes in the P wave amplitude histogram of the pacemaker. Incidence of undersensing was 25.8%; 9.3% of patients showed frequent (> 5%) or symptomatic undersensing. Patients with undersensing were older (76.6 ± 10.6 vs 64.2 ± 14.8 years), showed a lower minimum of intraoperative atrial potential amplitude (Pmin 0.86 ± 0.64 vs 1.43 ± 0.77 mV), a wider range of potential amplitude (ΔP 1.71 ± 1.44 vs 0.94 ± 0.84 mV), and a higher incidence of dipole placement in the low right atrium (50.0% vs 11.1%, P < 0.001 for all comparisons). In a multivariate regression analysis, patient age > 66 years, Pmin < 0.6 mV, > 1.3 mV and atrial dipol placement in the low right atrium were independently predictive for undersensing. Minimal atrial potential amplitude, range of potential amplitude, and atrial dipole position influence atrial sensing performance in single lead VDD pacing. Thus, implantation guidelines should reflect these rules to improve the outcome of VDD pacemaker recipients.
Analysis of Mode Switching Algorithms in Dual Chamber Pacemakers
Authors: ISRAEL CARSTEN W.
Published: July 2003

ISRAEL, C.W.: Analysis of Mode Switching Algorithms in Dual Chamber Pacemakers. Dual chamber systems are currently implanted in an increasing number of patients with a pacing indication and paroxysmal atrial tachyarrhythmias (ATAs). To avoid tracking of high atrial rates during ATA while providing AV synchronous pacing during sinus rhythm and AV block, automatic mode switching (MS) to a nontracking mode has been developed. Several concepts of MS algorithms have been introduced differing in sensitivity and specificity of ATA detection, delay between ATA onset and MS, pacing mode during MS, rapidity of MS termination upon detection of sinus rhythm, and special algorithms pertinent to MS. This review classifies and analyzes algorithms that are integrated into MS concepts and outlines considerations on optimal MS performance. Based on simulations and clinical studies, fast MS concepts avoiding high paced ventricular rates seem preferable but require special functions to avoid loss of AV synchrony by inappropriate MS. Similarly, fast return to tracking mode after ATA cessation seems preferable but requires algorithms to prevent mode oscillations. Sudden ventricular rate changes have to be avoided by rate smoothing functions, and an appropriate ventricular rate during nontracking mode has to be provided by rate responsive pacing. Programming of the device includes individual optimization of atrial sensitivity, atrial blanking times, and tachycardia detection rates. In addition, a high signal‐to‐noise ratio by careful atrial lead implantation, narrowly spaced bipolar atrial leads and a good sensing amplifier, together with special algorithms for atrial sensing adjustment improve the performance of MS algorithms.
Clinical Predictors of Defibrillation Thresholds with an Active Pectoral Pulse Generator Lead System
Authors: HODGSON DENICE M. , OLSOVSKY MARY R. , SHOROFSKY STEPHEN R. , DALY BARRY , GOLD MICHAEL R.
Published: July 2003

HODGSON, D.M., et al.: Clinical Predictors of Defibrillation Thresholds with an Active Pectoral Pulse Generator Lead System. Active pectoral pulse generators are used routinely for initial ICD placement because they reduce DFTs and simplify the implantation procedure. Despite the common use of these systems, little is known regarding the clinical predictors of defibrillation efficacy with active pulse generator lead configurations. Such predictors would be helpful to identify patients likely to require higher output devices or more complicated implantations. This was a prospective evaluation of DFT using a uniform testing protocol in 102 consecutive patients with an active pectoral can and dual coil transvenous lead. For each patient, the DFT was measured with a step‐down protocol. In addition, 34 parameters were assessed including standard clinical echocardiographic and radiographic measures. Multivariate stepwise regression analysis was performed to identify independent predictors of the DFT. The mean DFT was 9.3 ± 4.6 J and 93% (95/102) of patients had a DFT ≤ 15 J. The QRS duration, interventricular septum thickness, left ventricular mass, and mass index were significant but weak (R < 0.3) univariate predictors of DFT. The left ventricular mass was the only independent predictor by multivariate analysis, but this parameter accounted for < 5% of the variability of DFT measured (adjusted R2= 0.047, P = 0.017). The authors concluded that an acceptable DFT (< 15 J) is observed in > 90% of patients with this dual coil and active pectoral can lead system. Clinical factors are of limited use for predicting DFTs and identifying those patients who will have high thresholds.
Spatial Resolution of Body Surface Potential and Laplacian Pace Mapping
Authors: LI GUANGLIN , LIAN JIE , HE BIN
Published: July 2003

LI, G., et al.: Spatial Resolution of Body Surface Potential and Laplacian Pace Mapping. The spatial resolution (SR) of the body surface Laplacian map (BSLM) was assessed using a three‐dimensional, realistically shaped, heart‐torso model. The BSLMs were estimated from the body surface potential maps (BSPMs) generated by pacing different sites of the ventricle of a three‐dimensional computer heart model using a novel three‐dimensional spline Laplacian algorithm. Pacing was performed at a total of 88 myocardial units in five regions of the AV ring (anterior, left wall, posterior, right wall, and septum) and three regions adjacent to the AV ring in the middle anterior and posterior of the ventricles. The SR of the BSPMs and BSLMs were investigated by means of the correlation coefficient (CC) of maps. When 5 μV and 10 μV Gaussian white noises were added into the simulated BSPMs, the SR, at 36 ms after the onset of pacing, was about 5.0 ± 1.2 mm and 5.4 ± 1.3 mm for the BSPMs, and 3.3 ± 0.8 mm and 4.0 ± 0.9 mm for the BSLMs, respectively. The results of the present simulation study suggest that the BSLM has higher SR and may provide a more accurate means than the BSPMs for differentiating between the accessory pathways or the sites of other ectopic cardiac beats along the AV ring and in its neighboring regions.
The Effect of Rate Responsive Pacing in Patients with Angina Pectoris on the Extent of Ischemia on 201‐Thallium Exercise Scintigraphy
Authors: VAN CAMPEN LINDA C.M.C. , DE COCK CAREL C. , VISSER FRANS C. , VISSER CEES A.
Published: July 2003

VAN CAMPEN, L.C.M.C., et al.: The Effect of Rate Responsive Pacing in Patients with Angina Pectoris on the Extent of Ischemia on 201‐Thallium Exercise Scintigraphy. In patients with coronary artery disease (CAD), rate responsive pacing is considered to be contraindicated because an increase in heart rate may increase oxygen demand. Although previous studies have shown no subjective increase in ischemia during rate responsive pacing, data from objective assessment have not been documented. The goal of this study was to determine if there was an increase in ischemia on 201‐Thallium (201TI) exercise scintigraphy in this mode of pacing in patients with CAD and angina. Eighteen consecutive patients with chronic atrial fibrillation and symptomatic bradyarrhythmias with a pacemaker for more than 6 months participated in the study. In VVI and VVIR modes a symptom‐limited exercise 201TI scintigram was performed in a single blind randomized crossover fashion. Exercise duration, anginal attacks, use of nitroglycerine (NTG) tablets, blood pressure, and analysis of the scintigrams were assessed during each pacing mode. Fifteen men and three women were included (age 65.9 ± 4.9 years, LVEF 0.44 ± 0.07). Four were in Class III angina pectoris, and 14 in class II. The mean exercise duration increased 28% in the VVIR group without an increase in anginal attacks per week or the use of NTG tablets. On scintigrams, no differences were seen between the two groups. One patient was withdrawn from the study because of an increase in angina pectoris (AP) attacks during VVIR pacing. Rate responsive pacing is safe and effective in patients with CAD without an increase in subjective and objective signs of ischemia.
High Accuracy of Automatic Detection of Atrial Fibrillation Using Wavelet Transform of Heart Rate Intervals
Authors: DUVERNEY DAVID , GASPOZ JEAN‐MICHEL , PICHOT VINCENT , ROCHE FRÉDÉRIC , BRION RICHARD , ANTONIADIS ANESTIS , BARTHÉLÉMY JEAN‐CLAUDE
Published: July 2003

DUVERNEY, D., et al.: High Accuracy of Automatic Detection of Atrial Fibrillation Using Wavelet Transform of Heart Rate Intervals. Permanent and paroxysmal AF is a risk factor for the occurrence and the recurrence of stroke, which can occur as its first manifestation. However, its automatic identification is still unsatisfactory. In this study, a new mathematical approach was evaluated to automate AF identification. A derivation set of 30 24‐hour Holter recordings, 15 with chronic AF (CAF) and 15 with sinus rhythm (SR), allowed the authors to establish specific RR variability characteristics using wavelet and fractal analysis. Then, a validation set of 50 subjects was studied using these criteria, 19 with CAF, 16 with SR, and 15 with paroxysmal AF (PAF); and each QRS was classified as true or false sinus or AF beat. In the SR group, specificity reached 99.9%; in the CAF group, sensitivity reached 99.2%; in the PAF group, sensitivity reached 96.1%, and specificity 92.6%. However, classification on a patient basis provided a sensitivity of 100%. This new approach showed a high sensitivity and a high specificity for automatic AF detection, and could be used in screening for AF in large populations at risk.
The Effects of Reverse Atrial Electrical Remodeling on Atrial Defibrillation Thresholds
Authors: MANGRUM J. MICHAEL , EVERETT THOMAS H. , MITCHELL MARK A. , MCRURY IAN D. , LI HUI , HAINES DAVID E.
Published: July 2003

MANGRUM, J.M., et al.: The Effects of Reverse Atrial Electrical Remodeling on Atrial Defibrillation Thresholds. The implantable atrial defibrillator is a developing therapeutic option for paroxysmal atrial fibrillation, but shock related discomfort continues to be a limiting factor. To further characterize successful defibrillation, the relationship between reverse atrial electrical remodeling and internal atrial defibrillation thresholds in canines with chronic atrial fibrillation was examined. Testing was performed in 21 dogs. Chronic atrial fibrillation was induced in eight dogs by creating moderate mitral regurgitation and rapidly pacing the right atrium for ≥ 6 weeks. The atrial fibrillation cycle length, atrial effective refractory period, refractory period dispersion, and internal atrial defibrillation thresholds were determined after establishment of chronic atrial fibrillation after 4 hours of sinus rhythm postcardioversion and 7 days of sinus rhythm postcardioversion. These measurements were then compared to a normal population of 13 dogs. The atrial defibrillation thresholds were 6.6 J (1.9–10.1 J) initially, 2.9 J (1.5–3.7 J) after 4 hours of sinus rhythm, and 0.9 J (0.4 – 1.3 J) after 7 days of sinus rhythm (P = 0.04). This decrease was associated inversely with the atrial effective refractory period (P < 0.03), and atrial fibrillation cycle length (P < 0.05), and with a decrease in atrial refractory period dispersion after 7 days of sinus rhythm (P = 0.04). These electrophysiological measurements reached normal population levels by 7 days. Atrial defibrillation thresholds decrease as atrial reverse electrical remodeling occurs and this reduction corresponds to increased atrial fibrillation cycle length, increased atrial refractoriness, and decreased refractory period dispersion.
Relation Between the Pacing Induced Sequence of Activation and Left Ventricular Pump Function in Animals
Authors: PRINZEN FRITS W. , PESCHAR MAAIKE
Published: July 2003

PRINZEN, F.W., et al.: Relation Between the Pacing Induced Sequence of Activation and Left Ventricu‐lar Pump Function in Animals. The main goal of this article was to review animal experimental work on the effect of asynchronous activation on ventricular pump function. During normal sinus rhythm and atrial pacing, the Purkinje system contributes significantly to the rapid electrical activation of the ventricles. In contrast, during ventricular pacing the impulse is almost exclusively conducted through the normal myocardium. As a consequence, electrical activation of the ventricles becomes asynchronous and has an abnormal sequence. The abnormal impulse conduction causes considerable disturbances to occur in regional systolic fiber shortening, mechanical work, blood flow, and oxygen consumption; low values occurring in early activated regions and values above normal being present in late activated regions. Many animal studies have now shown that the abnormal electrical activation, induced by ventricular pacing, leads to a depression of systolic and diastolic LV function. Pacing at the right ventricular apex (the conventional pacing site) reduces LV function more than pacing at the high ventricular septum or at LV sites. In canine hearts with experimental LBBB, LV pacing significantly improves LV pump function. Differences in LV pump function between (combinations of) pacing sites are poorly correlated with QRS duration. Therefore, the cause of the depression of LV function during abnormal electrical activation appears to be a combination of the asynchrony and the sequence of activation. These experimental findings justify continuing attention for optimizing the site(s) of ventricular pacing in patients with normal and abnormal ventricular impulse conduction.
Intoxication with Taxus Baccata: Cardiac Arrhythmias Following Yew Leaves Ingestion
Authors: WILLAERT WILLEM , CLAESSENS PHILIP , VANKELECOM BART , VANDERHEYDEN MARC
Published: July 2003

WILLAERT, W., et al.: Intoxication with Taxus Baccata: Cardiac Arrhythmias Following Yew Leaves In‐gestion. The use of yew leaves (Taxus Baccata) as a means of deliberate self‐harm is infrequent. The potent effect of the toxin is primarily cardiac and results in rhythm alterations and ultimately ventricular fibrillation. As there is no known antidote, and classic antiarrhythmic therapy proves to be ineffective, a prompt diagnosis is of great importance as immediate supportive action is the only valuable alternative. This case describes a 43‐year‐old women who attempted suicide by ingesting the leaves of Taxus Baccata. We discuss the effects and the difficulty of treatment associated with yew leaf poisoning.
Importance of Using Standard Rather Than Torso Surface Electrocardiographic Leads for Pacemapping at the Right Ventricular Outflow Tract
Authors: MATSUSHITA TAKEHIKO , CHUN SUNG , CHAN NGAI YIN , GLATTER KATHY , SUNG RUEY J.
Published: July 2003

MATSUSHITA, T., et al.: Importance of Using Standard Rather Than Torso Surface Electrocardiographic Leads for Pacemapping at the Right Ventricular Outflow Tract. Although pacemapping has been used to localize the origin of ventricular tachycardia, the effect of changes in the position of ECG electrodes during ventricular pacing remains unknown. To clarify the relationship between the position of ECG limb electrodes and QRS configuration during pacemapping at the right ventricular outflow tract (RVOT), RVOT pacing was performed on 12 patients at eight pacing sites located in the anterior, septal, lateral, and posterior portions each in the high and low RVOT. Standard and torso ECGs were recorded simultaneously during each pacing protocol, and the QRS axis and amplitude were compared between the two ECGs. Differences between sites in the horizontal plane and in the longitudinal direction were also compared. The QRS axis on the torso ECG was significantly more rightward than that on the standard ECG at all eight pacing sites (72.1 ± 17.4 vs 64.0 ± 21.9 degrees). The magnitude of differences in the QRS axis and amplitude between the anterior and other sites at the same height was significantly greater in the standard ECG in all locations and in 7 of 18 comparable leads, respectively. The magnitude of differences between high and low sites was significantly greater in the standard ECG in three of four locations and in 5 of 12 comparable leads, respectively. In conclusion, the torso ECG is less sensitive to changes in pacing site at the RVOT than the standard ECG. The torso ECG is, therefore, not proper for pacemapping in attempts to ablate ventricular tachycardia arising from the RVOT.
Automatic Mode Switching of Implantable Pacemakers: I. Principles of Instrumentation, Clinical, and Hemodynamic Considerations
Authors: LAU CHU‐PAK , LEUNG SUM‐KIN , TSE HUNG‐FAT , BAROLD S. SERGE
Published: July 2003

LAU, C.‐P., et al.: Automatic Mode Switching of Implantable Pacemakers: I. Principles of Instrumentation, Clinical, and Hemodynamic Considerations. Automatic mode switching (AMS) is now a programmable function in most contemporary dual chamber pacemakers. Atrial tachyarrhythmias are detected when the sensed atrial rate exceeds a “rate‐cutoff,”“running average,”“sensor‐based physiological” rate, or using “complex” detection algorithms. AMS algorithms differ in their atrial tachyarrhythmia detection method, sensitivity, and specificity and, thus, respond differently to atrial tachyarrhythmia in terms of speed to the AMS onset, rate stability of the response, and speed to resynchronize to sinus rhythm. AMS is hemodynamically beneficial, and most patients with atrial tachyarrhythmias are symptomatically better with an AMS algorithm in their pacemakers. New diagnostic capabilities of pacemaker especially stored electrograms not only allow programming of the AMS function, but enable quantification of atrial fibrillation burden that facilitate clinical management of patients with implantable devices who have concomitant atrial tachyarrhythmia.
Ectopic Atrial Rhythm with Exit Block Following Catheter Ablation for Focal Atrial Tachycardias in a Patient with Prior Surgery for Atrial Septal Defect
Authors: OHKUBO KIMIE , WATANABE ICHIRO , KOJIMA TOSHIAKI , MASAKI RIKO , OSHIKAWA NAOHIRO , SUGIMURA HIDEZOU , OKUMURA YASUO , YAMADA TAKESHI , SAITO SATOSHI , OZAWA YUKIO , KANMATSUSE KATSUO
Published: July 2003

OHKUBO, K., et al.: Ectopic Atrial Rhythm with Exit Block Following Catheter Ablation for Focal Atrial Tachycardias in a Patient with Prior Surgery for Atrial Septal Defect. The patient was a 40‐year‐old woman with a history of surgery for atrial septal defect and catheter ablation for typical atrial flutter. An electrophysiological study was performed because she had palpitation and syncope. She had ectopic atrial rhythm originating from low lateral RA. Two focal atrial tachycardias ([1] superior vena cava‐RA junction and [2] a low posteroseptal RA) were successfully ablated. Following catheter ablation for the second atrial tachycardia, she developed junctional rhythm because ectopic atrial rhythm showed exit block. However, atrial activation of junctional rhythm could conduct into the ectopic atrial rhythm focus and reset the rhythm when atrial activation of junctional rhythm reached the blocked line after atrial refractoriness by preceding ectopic atrial rhythm.
Cardiac Stimulation Caused by Biogalvanic Current During Pacemaker Implantation
Authors: VAN GELDER BERRY M. , BRACKE FRANK A. , MEIJER ALBERT
Published: July 2003

VAN GELDER, B.M., et al.: Cardiac Stimulation Caused by Biogalvanic Current During Pacemaker Implantation. After lead positioning during implantation of a biventricular pacing system intermittent ventricular simulation was observed. There was no pacemaker connected to any of the leads, but ventricular capture could be provoked by an intermittent contact between the lead stylet, which was still partially inserted, and a self‐retaining retractor. The same phenomenon was observed from the atrial lead.
Pacemaker Lead Extraction with the Needle's Eye Snare for Countertraction via a Femoral Approach
Authors: KLUG DIDIER , JARWÉ MOUSTAPHA , MESSAOUDÉNE SEDDIK AIT , KOUAKAM CLAUDE , MARQUIÉ CHRISTELLE , GAY ALAIN , LACROIX DOMINIQUE , KACET SALEM
Published: July 2003

KLUG, D., et al.: Pacemaker Lead Extraction with the Needle's Eye Snare for Countertraction via a Femoral Approach. Femoral approach pacemaker lead extraction is described as a safe and efficacious procedure. When the lead can not be removed from its myocardial insertion, the “Needle's eye snare” has become available, and it allows a femoral approach traction associated with a countertraction . Between May 1998 and May 2000, 222 lead extraction procedures were performed in 99 patients using the femoral approach. This article reports the results of the 70 lead extractions requiring the use of the Needle's eye snare for femoral approach countertraction in 39 patients with a total of 82 leads. The indications were infection, accufix leads and lead dysfunction in 56, 1 and 6 leads, respectively. The age of the leads was 113 ± 56 months. Sixty‐one (87.2%) leads were successfully extracted, the extraction was incomplete in 3 (4.3%) cases and failed in 6 (8.5%) cases. The failures were due to leads totally excluded from the venous flow for four leads, the impossibility of advancing the 16 Fr long sheath through the right and left iliac veins for one lead and one traction induced a nontolerated ventricular arrhythmia. In these cases, an extraction by a simple upper traction had been attempted in another center several months before. The complications included two deaths and one transient ischemia of the right inferior limb. Despite the selection of a series of leads for which an extraction by a simple traction on the proximal end of the lead was impossible or unsuccessful, femoral countertraction seems to be a safe and efficacious procedure. The failure of this technique occurred in patients with damaged leads due to a previous extraction procedure performed in centers with limited experience in lead extraction.
Extraction of Pacemaker and Implantable Cardioverter Defibrillator Leads: Patient and Lead Characteristics in Relation to the Requirement of Extraction Tools
Authors: BRACKE FRANK , MEIJER ALBERT , VAN GELDER BERRY
Published: July 2003

BRACKE, F., et al.: Extraction of Pacemaker and Implantable Cardioverter Defibrillator Leads: Patient and Lead Characteristics in Relation to the Requirement of Extraction Tools. Effective tools for extraction of pacemaker and ICD leads have been developed in the past decennium. This study investigated the necessity of using these tools in addition to direct traction in relation to patient and lead characteristics. The study encompasses first attempts at extraction of consecutive pacemaker and ICD leads from the subpectoral area. A stepwise extraction protocol was used with traction first (directly or with a locking stylet) followed by laser sheath extraction if not successful. The indication, patient age, time from implant, fixation mechanism, location, and insertion site of the leads were studied in relation to the outcome of traction. A total of 145 leads in 83 patients were extracted. Leads were implanted for 71 ± 61 months. Indication for extraction was infection in 96 leads and malfunction in 49 leads. There were 90 ventricular leads including 16 ICD leads. Forty‐nine (34%) leads were extracted with traction; in 96 (66%) leads a laser sheath was necessary. All leads implanted for < 6 months could be removed with traction alone. In a multivariate logistic regression model, time from implant was the main factor determining success of traction (P < 0.001), but in case of infection the success rate increased (P = 0.004). In conclusion, time from implant is the decisive factor to judge the potential efficacy of lead extraction with direct traction. If leads are implanted for 6 months, the availability of additional extraction tools is necessary when lead extraction is considered. In addition to time from implant, infected leads have a better chance to be removed with traction although it is a much weaker predictor.
Experience with a Dual Chamber Implantable Defibrillator
Authors: KÜHLKAMP VOLKER , WILKOFF BRUCE L. , BROWN AMY B. , VOLOSIN KENT J. , HÜGL B. J. , STAFFORD WAYNE , CAMERON DOUGLAS A.
Published: July 2003

KÜHLKAMP, V., et al.: Experience with a Dual Chamber Implantable Defibrillator. An implantable defibrillator with dual chamber pacing may have advantages for pacing, sensing, and detection of bradyand tachyarrhythmias. This study evaluates the safety and performance of a dual chamber implantable cardioverter defibrillator that incorporates an algorithm to discriminate supraventricular from ventricular arrhythmias. The 300 patients in this study had the device implanted for the following indications: ventricular tachycardia (47%), sudden cardiac death survivorship (51%), and prophylactic implants (2%). Patients received dual chamber pacing for accepted bradyarrhythmic (51.7%) or investigational indications. During a mean follow‐up period of 1.7 months a total of 1,092 arrhythmia episodes in 96 patients were fully documented in the device memory: 66 patients experienced a total of 796 ventricular tachyarrhythmia episodes and 42 experienced a total of 296 supraventricular episodes. The device appropriately detected 100% of sustained ventricular tachyarrhythmias while reducing the inappropriate detection of supraventricular tachyarrhythmias by 72% compared to single chamber rate only detection. The positive predictive value was 90.5% for ventricular tachyarrhythmia detection in episodes that exceeded the tachycardia detection rate. Adverse events observed in at least 2% of the patients were incisional pain (22%), inappropriate ventricular detection (7%), atrial lead dislodgement (4%), atrial oversensing/undersensing (3%), hematoma (3%), incessant ventricular tachyarrhythmia (2%), and pneumothorax (2%). There were 13 deaths, none of which were attributed to device failure. The Gem DR is safe and effective for the detection and treatment of ventricular tachyarrhythmias. The dual chamber detection algorithm appropriately recognized supraventricular tachycardia with rapid ventricular rates 72% of the time while maintaining 100% detection of sustained ventricular tachyarrhythmias.
Determination of Standard Electrode Potential E° for Chronic Platinum and Gold Electrodes in Rat Muscle: Implications for Biosensors and the “Anode” of Bipolar Pacing
Authors: CHOU HOWARD A. , FRENKEL DANIEL , OVADIA MARC
Published: July 2003

CHOU, H.A., et al.: Determination of Standard Electrode Potential E° for Chronic Platinum and Gold Electrodes in Rat Muscle: Implications for Biosensors and the “Anode” of Bipolar Pacing. Pacemaker electrode surface modification by organosilane and organic self‐assembled monolayer strategies creates a possible new variable in pacemaker electrode behavior. Because all of these chemical surface coatings are unstable at extremes of potential, the potential to which the electrode relaxes (between pacing pulses) becomes extremely important. The authors measured this potential for platinum (Pt) and gold (Au) relevant for their use as anode (or cathode) in a bipolar pacing system and from this potential the standard electrode potential, E° was determined. Thirty‐Four determinations were made by a null current three‐electrode potentiostatic technique of 2.45 mm2 platinum or gold electrodes implanted chronically in blood perfused muscle in a spontaneously breathing rat. Linear voltage sweeps were performed while monitoring current with voltage at null current determined repeatedly at varying scan rates and limits. Electrode potential varied between‐–388 ± 19 mV (vs Ag/Ag‐) for platinum and‐388 ± 55 mV for gold electrodes. Hysteresis was observed in all sweeps (P < 0.008, Fisher's exact) and measured 61 ± 17 mV (anodic) and 25 ± 3 mV (cathodic) with steep dependence on polarity (P < 0.001, t‐test). The findings were independent of the materials' electronic work function. E° versus normal hydrogen electrode (NHE) were thus ‐166 mV (platinum) and‐166 mV (gold). Because the most common bipolar system uses platinum as anode, these results are directly applicable to current pacing technology. Provided low thresholds are achievable with novel surface modified electrodes, the small range of variation of E°, and the particular mean value observed, are both compatible with function, provided care is used during electrode testing to avoid surface disruption. These results are significant also for biosensors that use similar surface modification methodologies.
Electrocardiographic Appearance of Old Myocardial Infarction in Paced Patients
Authors: KOCHIADAKIS GEORGE E. , KALEBOUBAS MICHAIL D. , IGOUMENIDIS NIKOS E. , SKALIDIS EMMANUEL I. , SIMANTIRAKIS EMMANUEL N. , CHRYSOSTOMAKIS STAVROS I. , VARDAS PANOS E.
Published: July 2003

KOCHIADAKIS, G.E., et al.: Electrocardiographic Appearance of Old Myocardial Infarction in Paced Patients. This study evaluated the possibility of diagnosing chronic myocardial infarction in the presence of the pacing electrocardiogram. Forty‐five patients with known myocardial infarction (anterior 23, inferior 22) and 26 healthy controls were studied. After coronary angiography, pacing was applied from the right ventricular apex, and the sensitivity, specificity, and average diagnostic accuracy of five criteria on the paced electrocardiogram were assessed: (1) Notching 0.04 second in duration in the ascending limb of the S wave of leads V3, V4, or V5 (Cabrera's sign); (2) Notching of the upstroke of the R wave in leads I, aVL, or V6 (Chapman's sign); (3) Q waves > 0.03 second in duration in leads I, aVL, or V6; (4) Notching of the first 0.04 second of the QRS complex in leads II, III, and aVF; (5) Q wave > 0.03 second in duration in leads II, III, and aVF. The most sensitive criteria, for anterior and inferior myocardial infarctions were Cabrera's and Chapman's (91.1 and 86.6%, respectively). All criteria had low specificity (range 42.3–69.2%). The combination of Cabrera's and Chapman's sign decreased the sensitivity to 77.7%, but increased specificity to 82.2%. The sensitivity and specificity of all the criteria were independent of the myocardial infarction site. In paced patients, the application of electrocardiographic criteria, and especially the combination of Cabrera and Chapman, provides useful clinical information in recognizing prior myocardial infarction but not in assigning the specific infarct site.
Surgically Repaired Delayed Mitral Regurgitation After Radiofrequency Catheter Ablation for Wolff‐Parkinson‐White Syndrome
Authors: OHTSUKA TOSHIYA , MURAKAWA YUJI , HAYAMI NORIYUKI , KOTSUKA YUTAKA , TAKAMOTO SHINICHI
Published: July 2003

OHTSUKA, T., et al.: Surgically Repaired Delayed Mitral Regurgitation After Radiofrequency Catheter Ablation for Wolff‐Parkinson‐White Syndrome. This report describes a male patient with WPW syndrome who underwent surgical repair of sudden, severe mitral valve regurgitation through the posterior leaflet 20 months after successful RF catheter ablation for Kent bundle at the age of 14, and discusses the problem of valvular damage caused by this technique.
Addition of a Left Ventricular Lead to Conventional Pacing Systems in Patients with Congestive Heart Failure: Feasibility, Safety, and Early Results in 60 Consecutive Patients
Authors: BAKER CINDY M. , CHRISTOPHER THOMAS J. , SMITH PAIGE F. , LANGBERG JONATHAN J. , DELURGIO DAVID B. , LEON ANGEL R.
Published: July 2003

BAKER, C.M., et al.: Addition of a Left Ventricular Lead to Conventional Pacing Systems in Patients with Congestive Heart Failure: Feasibility, Safety, and Early Results in 60 Consecutive Patients. Left bundle branch block worsens congestive heart failure (CHF) in patients with LV dysfunction. Asynchronous LV activation produced by RV apical pacing leads to paradoxical septal motion and inefficient ventricular contraction. Recent studies show improvement in LV function and patient symptoms with biventricular pacing in patients with CHF. The aim of this study was to determine the feasibility, safety, acute efficacy, and early effect on symptoms of the upgrade of a chronically implanted RV pacing system to a biventricular system. Sixty patients with NYHA Class III and IV underwent the upgrade procedure using commercially available leads and adapters. The procedure succeeded in 54 (90%) of 60 patients. Acute LV stimulation thresholds obtained from leads placed along the lateral LV wall via the coronary sinus compare favorably to those reported in current biventricular pacing trials. The complication rate was low (5/60, 8.3%): lead dislodgement (n = 1), pocket hematoma (n = 1), and wound infections (n = 3). During 18 months of follow‐up (16.7%) of 60 patients died. Two patients that died failed the initial upgrade attempt. At 3‐month follow‐up, quality of life scores improved 31 ± 28 points (n = 29), P < 0.0001). NYHA Class improved from 3.4 ± 0.5 to 2.4 ± 0.7 (P = < 0.0001) and ejection fraction increased from 0.23 ± 0.8 to 0.29 ± 0.11 (P = 0.0003). Modification of RV pacing to a biventricular system using commercially available leads and adapters can be performed effectively and safely. The early results of this study suggest patients may benefit from this procedure with improved functional status and quality of life.
Soft Thrombus Formation in Radiofrequency Catheter Ablation
Authors: DEMOLIN JULIE M. , EICK OLAF J. , MÜNCH KUNO , KOULLICK EDOUARD , NAKAGAWA HIROSHI , WITTKAMPF FRED H.M.
Published: July 2003

DEMOLIN, J.M., et al.: Soft Thrombus Formation in Radiofrequency Catheter Ablation. During RF catheter ablation, local temperature elevation can result in coagulum formation on the ablation electrode, resulting in impedance rise. A recent study has also demonstrated the formation of a so‐called soft thrombus during experimental ablations. This deposit poorly adhered to the catheter tip and did not cause an impedance rise. The mechanism of soft thrombus formation and the role of the natural coagulation system are unknown. The formation of a soft thrombus was investigated experimentally by temperature‐controlled RF delivery in heparinized blood at different heparin concentrations and in serum. After 60 seconds of RF delivery in blood with an electrode target temperature of 80°C, a semisolidified mass had formed around the ablation electrode at all heparin concentrations. A smaller but structurally similar deposit had formed after RF delivery in serum. Scanning electron microscopy analysis revealed that these deposits consist of denaturized and aggregated proteins, and not of a classical thrombus. The formation of the so‐called soft thrombus results from heat induced protein denaturation and aggregation and occurs independent of heparin concentration and also in serum. The formation of such deposits may occur at temperatures well below 100°C, which may have important consequences for further development of ablation technologies.
Shock Coordinated with High Power of Morphology Electrogram Improves Defibrillation Success in Patients with Implantable Cardioverter Defibrillators
Authors: BERKOWITSCH ALEXANDER , CARLSSON JOERG , ERDOGAN ALI , GUETTLER NORBERT , NEUZNER JOERG , PITSCHNER HEINZ F.
Published: July 2003

BERKOWITSCH, A., et al.: Shock Coordinated with High Power of Morphology Electrogram Improves Defibrillation Success in Patients with Implantable Cardioverter Defibrillators. Animal studies have suggested that the success of defibrillation may depend on the properties of VF waveform obtained from the morphology electrogram (ME) at the time of the shock. The reliable identification of depolarization events in the fibrillatory signal can be achieved using adaptive estimation of the instantaneous signal power (P). The aim of this study was to investigate if a high P of the ME (PME) was related to ventricular DFT and if the upslope in ME can be associated with the depolarization event. A total of 575 VF (mean duration 10 s) episodes recorded and stored during ICD implantation in 77 patients with ventricular arrhythmias were used for analysis. The DFT was defined using a double step‐down test. The values of PME immediately before pulse delivery (Pshock) and shock outcomes were registered. The differences between Pshock of successful and failed defibrillation were tested with the Mann‐Whitney U test. The relationship between individual medians of Pshock (Pmed) and DFT was analyzed using the Kruskall‐Wallis H‐test. The coincidence between identified depolarization and upslope in ME was tested using the chi‐square test. A P value of 0.05 was set for an error probability. The Pshock in case of failed defibrillation was significantly lower than Pshock in successful cases by the pulses of any strength (P < 0.001). The test revealed a significant inverse correlation between Pmed and DFT with P < 0.001. The depolarization corresponded to the upslope of ME in 85% of cases. This study demonstrated that a high value of instantaneous power of ME indicates the optimal time for shock delivery. The implementation of this algorithm in ICDs may improve the defibrillation efficacy.
Incidence and Risk Factors of Upper Extremity Deep Vein Lesions After Permanent Transvenous Pacemaker Implant: A 6‐Month Follow‐Up Prospective Study
Authors: DO CARMO DA COSTA SERGIO SIDNEY , NETO AUGUSTO SCALABRINI , COSTA ROBERTO , CALDAS JOSÉ GUILHERME , FILHO MARTINO MARTINELLI
Published: July 2003

DO CARMO DA COSTA, S.S., et al.: Incidence and Risk Factors of Upper Extremity Deep Vein Lesions After Permanent Transvenous Pacemaker Implant: A 6‐Month Follow‐Up Prospective Study. The incidence of venous lesions after permanent pacemaker insertion is around 45%. However, this incidence has been based on retrospective studies in a small series; moreover, factors predicting the development of these venous injuries have not been clearly defined. The aim of this study was to identify the risk factors for higher incidence of upper extremity deep vein thrombosis after transvenous permanent pacemaker insertion. The study included 229 patients and the criteria were age above 12 years and first permanent transvenous pacemaker implant. Exclusion criteria were pulmonary embolism, lower or upper extremity deep venous thrombosis, previous use of central venous catheters, coagulation disturbances, and malignancy. Age, race, sex, underlying cardiac disease, functional class to heart failure, LVEF, venous access, number, material and caliber of the leads, and previous use of a transvenous temporary pacemaker were considered. Six months after the pacemaker was implanted, 202 patients were submitted to digital subtraction venography ipsilateral to pacemaker implant. The venographies were normal in 73 (36%) patients and abnormal in 129 (64%) patients. Patients with previous use of transvenous temporary leads (P = 0,0001, OR = 4,260, confidence limits = 2,133–8,465) and LVEF ≤ 40% (P = 0,0378, OR = 3,437, confidence limits = 1,064–12,326), had higher incidence of venous lesions. Previous use of a temporary pacemaker and LVEF ≤ 0.40 were considered independent risk factors to a higher incidence of venous stenosis or thrombosis 6 months after permanent pacemaker insertion.
Heart Rate Variability and Autonomic Nervous System Changes in Children with Vasovagal Syncope
Authors: ALEHAN DURSUN , AYABAKAN CANAN , ÖZER SEMA
Published: July 2003

ALEHAN, D., et al.: Heart Rate Variability and Autonomic Nervous System Changes in Children with Vasovagal Syncope. The aim of this study was to evaluate the HRV at rest and during tilt test (HUTT) in children with a history of vasovagal syncope and to link the HRV indices with the clinical results of the test. HRV indices were assessed in the supine position and during the initial 5 minutes of the 60‐degree HUTT in 49 patients (33 females, 16 males, mean age of 13 ± 2.8 years) who were evaluated for recurrent syncope. The positive to negative results of the test were 21 to 28. The normalized power of high frequency component (npHF) decreased, normalized power of low frequency component (npLF) and the LF:HF ratio increased during HUTT of tilt‐positive patients (P < 0.05 for each parameter). Parallel changes, but to a lesser degree, were observed for similar HRV parameters of tilt‐negative patients. In addition, the HF and all the time‐domain indices decreased significantly (P ≤ 0.05) during HUTT in the latter group. When the tilt‐positive and‐negative patients were compared, the npHF was lower (P = 0.002), npLF and LF:HF ratio were higher (P = 0.01 and P = 0.001, respectively) during the test in tilt‐positive patients, reflecting increased sympathetic tone in this group. A cut‐off point for LF:HF was assigned as 2.7 for differentiating tilt‐negative and tilt‐positive results. The specificity, sensitivity, and positive and negative predictive values of this cut‐off point were calculated as 93%, 52%, 85%, and 41%, respectively. Patients with vasovagal syncope show variations in vagal autonomic tone and appear to be more prone to syncope when their sympathetic tone is elevated at the beginning of the test. LF:HF > 2.7 is a specific marker (specificity 93%) and can correctly predict a positive tilt test in 85% of patients.
Relation of Magnetocardiographic Arrhythmia Risk Parameters to Delayed Ventricular Conduction in Postinfarction Ventricular Tachycardia
Authors: KORHONEN PETRI , PESOLA KATJA , JÄRVINEN ANTERO , MÄKIJÄRVI MARKKU , KATILA TOIVO , TOIVONEN LAURI
Published: July 2003

KORHONEN, P., et al.: Relation of Magnetocardiographic Arrhythmia Risk Parameters to Delayed Ventricular Conduction in Postinfarction Ventricular Tachycardia. Time‐domain late field and intra‐QRS fragmentation parameters in magnetocardiography (MCG) identify patients prone to VT after myocardial infarction. This study investigated if they are related to slow ventricular conduction and affected by arrhythmia surgery. Twenty‐two patients with old myocardial infarction undergoing map‐guided subendocardial resection to treat sustained VT were included. Bipolar electrograms were recorded during operation using an epicardial jacket and endocardial balloon electrode array. The time from the QRS onset to the end of local ventricular excitation in each electrogram was measured during sinus rhythm. Multichannel MCG was recorded before and after operation and filtered QRS duration (QRSd), root mean square amplitude of the magnetic field strength during the last 40 ms of the QRS complex (RMS40), duration of the low amplitude signal < 300 fT (LAS300), fragmentation index M (M), and fragmentation score S (S) were determined. All patients had one or two VT foci localized and resected. MCG parameters correlated with time to the latest end of ventricular excitation; r = 0.45 for QRSd (P = 0.035), r = 0.64 for M (P = 0.001), and r = 0.73 for S (P < 0.001). The correlations were even better in patients with anterior infarction (e.g., r = 0.87 for QRSd, P < 0.001; r = 0.91 for M, P < 0.001). The operation reduced the abnormalities in MCG parameters and 20 of the 21 patients tested postoperatively became noninducible. MCG parameters indicating postinfarction arrhythmia propensity are related to delayed ventricular conduction. Abolition of the arrhythmia substrate reverses the abnormality of these parameters.
Impact of the Distribution and Structure of Myocardium in the Pulmonary Veins for Radiofrequency Ablation of Atrial Fibrillation
Authors: WEISS CHRISTIAN , GOCHT ANDREAS , WILLEMS STEPHAN , HOFFMANN MATTHIAS , RISIUS TIM , MEINERTZ THOMAS
Published: July 2003

WEISS, C., et al.: Impact of the Distribution and Structure of Myocardium in the Pulmonary Veins for Radiofrequency Ablation of Atrial Fibrillation. Focal AF is frequently triggered by ectopic beats mostly originating from the pulmonary veins (PVs). So far, the morphological substrate for this entity is not well defined. Therefore, the distribution of myocardial cells within the PV were examined as potential target sites for RF application. The PVs (118) of 30 human autopsied hearts (age of death 63 ± 13 years, 17 men) were dissected in their complete circumference starting 1 cm from the ostium. Tissue sections of the PV were stained with hematoxylin‐eosin and with Masson's trichrome. To characterize the developmental state of the myocardial tissue in the PV, immunohistochemistry was performed with antibodies reacting with antigens which are stage specifically expressed during cardiac development (HNK1/Leu7, α‐SMA, calponin and desmin). Furthermore, proliferative activity was assessed using antibodies against the Ki‐67 antigen (MIB‐1). In two hearts a left‐sided common PV ostium was found. The other hearts showed four separated PV ostia. The ostium diameter of the right inferior PV (1.2 ± 0.3 cm) was significantly smaller (P < 0.05) than remaining PV ostia (right superior 1.5 ± 0.2, left superior, 1.5 ± 0.3 and left inferior 1.4 ± 0.3 cm) of the 118 specimen. There was no significant difference in the presence of myocardium in the PV 1‐cm distant from the ostium comparing the right superior (78%), the right inferior (81%), the left superior (81%), and the left inferior (81%) PV. In 54% of cases the myocardial bundles covered the complete PV circumference. In up to 38% of the small extensions of the myocardial bundles myocardial cells, characterized by distinct cross‐striations and spindle shape were found. However, since these cells could not be labeled for other markers than desmin, their immature state seems unlikely. The anatomic distribution of myocardium in the PV suggests that RF applied to the entire circumference may be frequently required for its electrical isolation. Whether spindle‐shaped myocytes have different electrophysiological behavior has to be further investigated.