bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Nonfluoroscopic Navigation System to Guide Pulmonary Vein Isolation
Authors: TONDO CLAUDIO , MANTICA MASSIMO , RUSSO GIOVANNI , KARAPATSOUDI ELENI , LUCCHINA ARIANNA , NIGRO FRANCO , WILD MICHAELA , MOLINARO CRISTINA , BAVILA ROBERTO
Published: January 2005

Different techniques have been proposed to treat atrial fibrillation (AF) by catheter ablation. This study compares a new three‐dimensional (3D) nonfluoroscopic navigation system with conventional fluoroscopy to guide pulmonary vein (PV) isolation. A total of 60 consecutive patients with paroxysmal or persistent AF were randomly assigned to 3D‐guided ablation (group 1, n = 30), versus conventional fluoroscopy guidance ablation (group 2, n = 30). Complete PV isolation was achieved in both groups. The mean duration of fluoroscopy exposure (22 ± 8 vs 56 ± 10 minutes), and radiofrequency delivery (5 ± 1 vs 10 ± 3 minutes) were significantly shorter in group 1 than in group 2, P < 0.05 for both comparisons). The mean procedural time in group 1 was longer (225 ± 15 minutes) than in group 2 (156 ± 10 minutes, P < 0.05) due to the learning curve and time spent to generate the 3D maps. Over a mean follow‐up of 7 ± 2 months, 6 patients (20%) in group 2 had AF recurrences compared to 3 patients (10%) in group 1 (ns). The new nonfluoroscopic 3D system allows a high‐resolution reconstruction of the left atrium and PVs. It significantly reduces the mean radiofrequency delivery and fluoroscopy times as opposed to ablation performed under fluoroscopy guidance.
Rhythm Classification by Correlation‐Waveform Morphology Analysis of Atrial and Ventricular Electrogram Signals
Authors: SABA SAMIR , XI QIN , GANZ LEONARD , HEGGS KEVIN , CLONTZ RICK , PARKINSON DOUGLAS , WANG PAUL J. , SYED ZAFFER A.
Published: January 2005

We tested the use of correlation‐waveform analysis (CWA) of atrial and ventricular electrograms (EGMs) to distinguish ventricular tachycardia (VT) from supraventricular tachycardia (SVT). Patients undergoing electrophysiologic testing were enrolled. EGMs recorded during induced tachycardias were compared with EGMs recorded during sinus and paced rhythms, taken as templates, by assigning a CWA percent‐match (CPM) score. Twenty‐two patients were studied: 15 men and 7 women (mean age 48 years); 16 with SVT and 6 with VT. Using a sinus‐rhythm template, the atrial CPM scores for SVT and VT were 66%± 20% and 93%± 5%, respectively (P = 0.0034). With a CPM‐score cutoff of 85%, the sensitivity for correctly identifying VT was 100% and the specificity for rejection of SVT was 80%. The corresponding ventricular‐CPM scores for SVT and VT were 81%± 12% and 72%± 24%, respectively (P = 0.13, cutoff = 65%, sensitivity = 50%, and specificity = 90%). Using a ventricular template with atrial pacing, the ventricular‐CPM scores for SVT and VT were 87%± 9% and 76%± 14%, respectively (P = 0.028, cutoff = 70%, sensitivity = 50%, and specificity = 93%). Atrial CWA matching is superior to ventricular CWA matching in discriminating between SVT and VT. CWA matching in both chambers could potentially achieve better discrimination.
Changes in Autonomic Nervous Activity after Catheter Ablation of Atrial Tachycardia Arising from the Atrioventricular Annulus
Authors: KONGO MARIKO , FUJII EITARO , MATSUOKA KOJI , UCHIDA FUMIYA , OKUBO SETSUYA , KASAI ATSUNOBU , OMICHI CHIKAYA , ISAKA NAOKI , NAKANO TAKESHI
Published: January 2005

Radiofrequency (RF) catheter ablation of supraventricular tachycardias causes local parasympathetic denervation. This study used heart rate variability (HRV) to evaluate the effects of ablation of atrial tachycardia (AT) arising from the atrioventricular annulus (AVAT) on autonomic function. Ten patients with AVAT were referred for ablation (group AT) and compared with 8 patients with paroxysmal atrial fibrillation who underwent PV isolation (group Paf), and 13 patients with idiopathic ventricular tachycardia successfully treated by ablation (group VT). Time and frequency domain analysis of HRV on 24‐hour ambulatory ECG recordings was performed before and after ablation. Root mean square of differences of consecutive N‐N intervals (rMSSD), percentage of difference between consecutive N‐N intervals >50 ms (pNN50), and high frequency (HF) component were measured to examine the effects on parasympathetic nerve activity. In group AT, rMSSD, pNN50, and HF decreased significantly after ablation, while they remained unchanged in group Paf and group VT. These observations suggest that parasympathetic denervation after ablation was limited to group AT, and depended on the site of energy delivery along the tricuspid or mitral valve as opposed to atrial or ventricular muscle.
Evaluation of the Atrial Evoked Response for Capture Detection with High‐Polarization Leads
Authors: SPERZEL JOHANNES , BINNER LUDWIG , BORIANI GIUSEPPE , BIFFI MAURO , SNELL JEFF , SCHEINER JÖRG , PARK EULJOON , BORNZIN GENE
Published: January 2005

AutoCapture™ based on the evoked response can be confounded by electrode polarization. In this study, polarization was measured in human subjects who had chronic atrial leads. The aim of the study was to determine whether electrode polarization can be measured using a time integral atrial evoked‐response integral (AERI) of the negative portion of the atrial paced ER evoked‐response signal and to determine whether high‐polarization atrial leads unsuitable for AutoCapture™ can be identified a priori. Atrial intracardiac‐electrogram (IEGM) signals from 39 patients with implanted pacemakers were recorded and analyzed. The signals were recorded during conventional atrial‐threshold searches. A total of 221 atrial‐capture thresholds were recorded, ranging from 0.25 to 2.75 V with a mean of 0.79 V. Each evoked response was evaluated using the AERI in a 36 ms window following the 0.4 ms atrial stimulus. The polarization was estimated as a linear function of stimulus voltage using the evoked‐response signal integral of captured beats identified on the IEGM. The 221 threshold‐search datasets were obtained using leads with eight different electrode materials. Polarization could be measured using AERI as a function of stimulus voltage. Furthermore, this polarization measure can be used to identify high‐polarization leads, which are ill suited for the atrial AutoCapture™ algorithm.
Transvenous Catheter Cryoablation for Treatment of Atrial Fibrillation:
Authors: HOYT ROBERT H. , WOOD MARK , DAOUD EMILE , FELD GREGORY , SEHRA RUCHIR , PELKEY WILLIAM , KAY G. NEAL , CALKINS HUGH ,   U.S. CryoCor Investigators
Published: January 2005

Pulmonary vein (PV) isolation using radiofrequency (RF) ablation can induce PV stenosis. Cryoablation may offer a safer alternative energy source for PV isolation. PV isolation with cryoablation was attempted in 31 patients with paroxysmal atrial fibrillation (AF). Event monitors were used to measure the AF episode burden. Serial spiral CT scans were obtained to monitor PV stenosis pre‐ and postcryoablation. Cryoablation was immediately successful for PV isolation in 29 of 31 patients (94%), with 5.9 ± 1.2 months of follow‐up. Additional RF ablation was performed for AF recurrences in seven patients. The remaining 22 patients with a single cryoablation procedure demonstrated a time‐dependent, long‐term reduction in the frequency of AF episodes. At 6 months of follow‐up, 18 of 22 of cryo‐treated only patients (82%) were free of symptomatic AF episodes, and antiarrhythmic drugs were discontinued in 12 of 22 patients. Serial spiral CT scans demonstrated no change in the cryo‐treated PV ostial diameter. PV cryoablation was effective to control paroxysmal AF in most patients. Early recurrences of AF postcryoablation were common, though tended to resolve within 6 months postablation, consistent with a process of reverse atrial remodeling. Cryoablation of the PVs did not cause PV stenosis or other serious adverse events.
Incidence and Prevention of Cardiac Tamponade Complicating Ablation for Atrial Fibrillation
Authors: HSU LI‐FERN , JAÏS PIERRE , HOCINI MÉLÈZE , SANDERS PRASHANTHAN , SCAVÉE CHRISTOPHE , SACHER FREDERIC , TAKAHASHI YOSHIHIDE , ROTTER MARTIN , PASQUIE JEAN‐LUC , CLÉMENTY JACQUES , HAÏSSAGUERRE MICHEL
Published: January 2005

Cardiac tamponade complicating catheter ablation of atrial fibrillation (AF) occurs in approximately 1% of pulmonary vein isolation (PVI), and up to 6% of linear ablation procedures. We reviewed 348 consecutive AF ablation (including repeat) procedures over 1 year, which all included PVI, with additional linear lesions at the mitral isthmus in 73%, and cavotricuspid isthmus (CTI) in 76%. An irrigated‐tip ablation catheter was used, with power limited to 25–35 W for PVI and 45–60 W for linear lesions. Tamponade occurred in seven men and three women (2.9% of the population) during the creation of linear ablation lesions. Mechanical perforations occurred in two patients, and “popping” during radiofrequency (RF) energy delivery at the mitral isthmus in six, and at the CTI in two patients. Peak RF power was significantly higher in patients with than without tamponade (53 ± 4 W vs 48 ± 7 W; P = 0.02), and was greater than 48 W in all cases of “popping.” In the following year, RF power for linear ablation was limited to ≤42 W. Among 398 procedures, tamponade occurred in four patients (1.0%; P = 0.047 vs first year), three from “popping” and one from mechanical trauma. Procedural success rate remained the same despite reduction of power. Risk of tamponade was highest during linear ablation, mainly associated with high energy delivery and “popping.” Reducing the energy limited, though did not eliminate this complication.
Autonomic Modulation of Sinus and Atrioventricular Nodes in Premature Low‐Birth‐Weight Infants
Authors: HATA TADAYOSHI , MATSUURA HIDEAKI , MIYATA MASAFUMI , YOSHITANI YOSHIMI , NAGAOKA SHUNJI , SANO YOKO , SUZUKI KENJI , YAMAZAKI TOSHIO
Published: January 2005

Respiratory vagal activity is expressed by heart rate variability (HRV) at approximately 1 month of age in premature low‐birth‐weight infants (PLBWI). However, the autonomic inputs into the sinus node (SAN) and atrioventricular node (AVN) in PLBWI are unclear. We evaluated the variability in PP and PR intervals at day zero (day 0) and 1 month (1 month) after birth in 16 PLBWI (gestation 32.3 ± 1.3 weeks, birth weight 1.578 ± 257 g). The polygraph was recorded during sleep on day 0 and at 1 month. PP and PR intervals and the number of respiratory cycles were measured, and frequency analysis was performed by auto‐correlation fast Fourier transforms. Power spectral density (PSD: ms2) was calculated for the low frequency domain (LF: 0.036∼0.146 Hz), high frequency domain (HF: 0.146∼0.390 Hz), total frequency (TF: 0.036∼2.000 Hz), and respiratory sinus arrhythmia (RSA: frequency bandwidth of 0.3 Hz with peak respiratory frequency as median), and the PSD ratio in the PP and PR intervals (LF/HF, RSA/TF) were compared. Compared with day 0, a decrease in the LF/HF ratio and an increase in the RSA/TF ratio in PP intervals were observed at 1 month, consistent with expression of respiratory vagal activity. For PR intervals, on the other hand, the LF/HF ratio increased, indicative of accentuated sympathetic activity. However, the respiratory vagal input was weak, and the RSA/TF ratio remained unchanged. These observations suggest that, in PLBWI at 1 month, AVN conduction was not predominatly influenced by respiratory‐related vagal activity, but was controlled by autonomic regulation, independent of the SAN.
Bifocal Right Ventricular Cardiac Resynchronization Therapies in Patients with Unsuccessful Percutaneous Lateral Left Ventricular Venous Access
Authors: O'DONNELL D. , NADURATA V. , HAMER A. , KERTES P. , MOHAMMED U.
Published: January 2005

Biventricular cardiac resynchronization therapy (CRT) with a lateral left ventricular (LV) lead cannot always be achieved. We report a single center experience of CRT utilizing a protocol that specifically required the implantation of a bifocal right ventricular (RV) lead system when lateral LV pacing could not be achieved. Consecutive candidates for CRT were included in the study. If strict criteria for lateral LV pacing were not met, they underwent implantation of a bifocal RV lead system with two 7F, active fixation leads, one placed septally at the apex, and the other in the high septal outflow tract. All patients were followed for 12 months and the two groups were compared. A biventricular (BiV) stimulation system was implanted in 44 patients, and a bifocal RV system in six. The demographic characteristics of the two groups were similar. Both groups experienced a similar improvement in functional capacity, increase in 6 minutes walking distance, and decreased need for hospitalizations. The mean increase in LV ejection fraction was 11% in the bifocal RV group versus 10% in the BiV group. Though the tissue Doppler indices of LV synchrony improved earlier in the BiV group, (19% vs 10%) the improvement was similar in both groups at 6 months (23% vs 20%). The clinical improvements conferred by CRT can be matched by a bifocal RV system in selected patients. This alternate approach should be considered when implantation of a LV lateral lead was unsuccessful.
Long‐Term Variations in Optimal Programming of Cardiac Resynchronization Therapy Devices
Authors: O'DONNELL D. , NADURATA V. , HAMER A. , KERTES P. , MOHAMMED U.
Published: January 2005

The optimal follow‐up and long‐term programming of cardiac resynchronization therapy (CRT) devices are uncertain. The aim of this study was to quantify the temporal variations in programming parameters to optimize the follow‐up of these devices. Before, during, and at specified intervals over 9 months after implant, 40 recipients of CRT devices were studied. At each visit, the patients were tested with a fixed sequence of stimulation parameters during echocardiographic and electrocardiographic (ECG) recordings. The optimal AV delay and inter‐ventricular delays (V‐V) were determined according to echocardiographic criteria. The echocardiographic data were, in turn, compared with the ECG recordings. Among the 40 patients, the optimal stimulation parameters remained unchanged throughout the follow‐up in only three patients. In 18 patients, adjustments were required at each follow‐up sessions. There was a trend toward reduction in the left ventricular (LV) predominance of the optimal V‐V delay and an increase in the AV delay during follow‐up. The mean optimal V‐V delay at implant was 22 ms (−12 to +32 ms) with the LV activated first, versus 12 ms (−16 to +32 ms) at 9 months. The mean AV delay at implant was 115 ms versus 137 ms at 9 months. Individual changes could not be accurately predicted. The optimal stimulation parameters for CRT vary over time. Detailed, regular reevaluations, and reprogramming of optimal parameters may be appropriate.
Potential Cost Savings by Telemedicine‐Assisted Long‐Term Care of Implantable Cardioverter Defibrillator Recipients
Authors: FAUCHIER LAURENT , SADOUL NICOLAS , KOUAKAM CLAUDE , BRIAND FLORENT , CHAUVIN MICHEL , BABUTY DOMINIQUE , CLEMENTY JACQUES
Published: January 2005

Home monitoring (HM) of cardioverter defibrillators (ICD) with its automated wireless remote data access, may decrease the rate of patient visits. This study examined the potential cost savings for the long‐term care of ICD assisted by HM. A French database including 502 patients from 6 university hospitals was used. Costs of conventional follow‐up (FU) of ICD were calculated without, and compared with the expected cost of FU with HM. Calculations included number of visits, including physician's fees, electrocardiograms, and specific ICD surveillance, and transportation costs. The mean distance between home and institutions performing follow‐ups was 69 ± 57 km. For each visit, a mean overall cost of $215 was calculated, including $121 for transportation and $94 for medical services. HM may obviate up to 2 visits per year. Over the 5 years of expected life of the device, the decrease in costs for FU visits was estimated at $2,149. With an additional cost of $1,200 for the HM system, saving began after a mean FU of 33.5 months. The time to onset of cost saving by HM ranged between 17.4 months for patients living >150 km from the medical facility to 52.2 months for those living <50 km away. It is concluded that the HM may considerably reduce the overall costs of ICD FU by saving on transportation cost, particularly when the distance between home and medical facility is >100 km.
Expression of Opioid Receptor Subtypes and Their Ligands in Fibrillating Human Atria
Authors: LENDECKEL UWE , MÜLLER CORNELIA , RÖCKEN CHRISTOPH , LAUBE BRITTA , TÄGER MICHAEL , HUTH CHRISTOF , KLEIN HELMUT U. , GOETTE ANDREAS
Published: January 2005

The δ‐ and κ‐receptor subtypes are both abundantly expressed in the human heart and participate in age‐ and stress‐related alterations of cardiac function. Opioid receptor agonists mediate cardioprotection in response to ischemic preconditioning via increased intracellular Ca2+ levels, opening mitochondrial KATP channels, and PKC activation. We studied the expression of opioid receptor subtypes κ and δ, and of their ligand precursors, proopiomelanocortin (POMC) and preproenkephalin A (PENKA), in human atrial tissue of patients in sinus rhythm (SR), or persistent atrial fibrillation (AF). The mitochondrial size was also compared between the two groups. The atrial mRNA expression of opioid peptide precursors and receptors was assessed by competitive and real‐time RT‐PCR in 16 patients in AF and 16 patients in SR. Mitochondria were analyzed in the atrial tissue by electron microscopy in four patients in AF and four patients in SR. Both PENKA (SR: 100 ± 33% vs AF: 33 ± 21%; P < 0.05) and κ‐receptor mRNA amounts (AF: 78 ± 20% vs SR: 100 ± 11%; P < 0.05) were both decreased in AF in comparison to SR. In addition, POMC mRNA levels were decreased in AF (SR: 100 ± 54% vs AF: 37 ± 26%; P < 0.05), whereas the expression of the corresponding δ‐opioid receptor was unchanged (AF: 102 ± 34% vs 100 ± 44%). Mitochondrial size was increased during persistent AF. Persistent AF is associated with the down‐regulation of the opioid receptor/ligand expression. This suggests a loss of protective capacity in the fibrillating atrial tissue, resulting in an ultrastructural remodeling of atrial myocytes.
Biatrial Epicardial Pacing Prevents Atrial Fibrillation and Confers Hemodynamic Benefits After Coronary Artery Bypass Surgery
Authors: NAITO SHIGETO , TADA HIROSHI , KANEKO TATSUO , OSHIMA SHIGERU , TANIGUCHI KOICHI
Published: January 2005

Biatrial pacing (BIP) can be more effective than standard right atrial pacing (RAP) in preventing atrial fibrillation (AF) after coronary artery bypass graft surgery (CABG). However, the mechanisms and hemodynamic benefits of BIP have not been studied in detail. This study examined the efficacy and hemodynamic benefits conferred by overdrive epicardial BIP in preventing post‐CABG AF. After undergoing CABG, 72 patients (mean age = 66 ± 12 years, 48 men) were randomly assigned to triggered BIP (BIP‐AAT; n = 50) versus single RAP (RAP‐AAI; n = 22). The hemodynamic effects of BIP were measured by right heart catheterization and echocardiography. The patients were monitored for 8.8 ± 2.4 days after CABG to detect episodes of AF. The incidence of AF was significantly lower in the BIP‐AAT group (22.0%) than in the RAP‐AAI group (59.1%, P < 0.01). Cardiac output was significantly higher and pulmonary artery wedge pressure (PAWP) significantly lower during BIP‐AAT than during RAP‐AAI. The E‐wave (65.2 ± 37.8 vs 57.8 ± 37.8 cm/s, P < 0.05) was significantly higher during BIP‐AAT, and the interval between atrial pacing spike and the end of A‐wave (241 ± 18.4 vs 286 ± 17.2 ms, P < 0.001) was significantly shorter during BIP‐AAT than during RAP‐AAI. Triggered BIP was well tolerated and significantly reduced the incidence of post‐CABG AF compared to single‐site RAP. The hemodynamic improvements conferred by BIP‐AAT were due to a shortening of the inter‐atrial conduction delay and greater contribution of left atrial contraction. These hemodynamic benefits may play a role in lowering intra‐atrial pressure and in preventing AF.
Coronary Artery Disease Alters Ventricular Repolarization Dynamics in Type 2 Diabetes
Authors: VRTOVEC BOJAN , SINKOVEC MATJAZ , STARC VITO , RADOVANCEVIC BRANISLAV , SCHLEGEL TODD T.
Published: January 2005

Ventricular repolarization dynamics (VRD) is an important predictor of outcome in diabetes.We examined the potential impact of coronary artery disease (CAD) on VRD in type 2 diabetic patients. We recorded 5‐minute high‐resolution resting electrocardiograms in 38 diabetic patients undergoing elective coronary angiography, and in 38 age‐ and gender‐matched apparently healthy subjects (controls). Using leads‐I and ‐II, time‐domain indices of VRD were calculated. Coronary angiography was regarded as positive if ≥ 50% stenosis was found. Angiography was positive in 21 diabetic patients (55%). Patients with CAD had a significantly higher degree of VRD than controls (SDNN(QT): 15.81 ± 7.22 ms versus 8.94 ± 6.04 ms; P < 0.001, rMSSD(QT): 21.02 ± 7.07 ms versus 11.18 ± 7.45 ms; P < 0.001). Ventricular repolarization dynamics in diabetic patients with negative angiograms did not differ from VRD in controls (SDNN(QT): 8.94 ± 6.04 ms versus 7.44 ± 5.72 ms; P = 0.67, rMSSD(QT): 11.18 ± 7.45 ms versus 10.22 ± 5.35 ms; P = 0.82). CAD increases VRD in patients with type 2 diabetes. Therefore, changes in ventricular repolarization in diabetic patients may be due to silent CAD rather than due to diabetes per se.
Simultaneous Mapping in the Left Sinus of Valsalva and Coronary Venous System Predicts Successful Catheter Ablation from the Left Sinus of Valsalva
Authors: ITO SACHIKO , TADA HIROSHI , NAITO SHIGETO , KUROSAKI KENJI , UEDA MAREHIKO , SHINBO GORO , OSHIMA SHIGERU , NOGAMI AKIHIKO , TANIGUCHI KOICHI
Published: January 2005

Idiopathic ventricular tachycardia originating from the left epicardium (Epi‐VT) can be ablated from the left sinus of Valsalva (LSV) in selected patients. We hypothesized that the analysis of electrograms at the LSV and transitional zone from the great cardiac vein to the anterior interventricular vein (GCV‐AIV) could predict the efficacy of radiofrequency catheter ablation (RFCA) from the LSV. Simultaneous mapping in the LSV and coronary venous system was performed in 25 patients (12 VTs and 13 premature ventricular contractions). The earliest ventricular activation (VA) during the arrhythmias was found at the LSV or GCV‐AIV in all patients. RF applications from the LSV were successful in 17 patients success group (S‐Gr) and failed in 8 failure group (F‐Gr). The earliness of the VA recorded in the LSV (VA[LSV]) and in GCV‐AIV (VA[GCV‐AIV]) was compared between the two groups. (1) The VA[LSV] preceded the QRS onset by 28 ± 11 ms in S‐Gr and 14 ± 10 ms in F‐Gr (P < 0.01). (2) In S‐Gr, the VA[GCV‐AIV] was earlier than the VA[LSV] in 5 five patients (35%). However, in F‐Gr, the VA[GCV‐AIV] was earlier than the VA[LSV] in all patients. (3) In patients in whom the earliest VA was found at the LSV or GCV‐AIV, a VA [GCV‐AIV] preceding the VA[LSV] by less than 10 ms identified successful RFCA from the LSV with a sensitivity of 88 %, specificity of 100%, and high predictive value. With a detailed analysis of the electrograms recorded from the GCV‐AIV and LSV, it was possible to identify the successful catheter ablation of Epi‐VT from the LSV.
Characteristics of Bifocal Pacing:
Authors: RES JAN C.J. , BOKERN MARCEL J.J.A. , VOS DICK H.S.
Published: January 2005

Bifocal RIGHT ventricular stimulation (BRIGHT) is an ongoing, randomized, single‐blind, crossover study of atrial synchronized bi‐right ventricular (RV) pacing in patients in New York Heart Association heart failure functional class III, a left ventricular ejection fraction <35%, left bundle branch block and QRS complexes ≥120 ms. This analysis compared the electrical and handling characteristics, and the complications of pacing at the RV apex (Ap) with passive, versus RV outflow tract (OT) with active fixation leads. A mean of 1.6 ± 0.9 and 2.2 ± 2.0 attempts were needed to position the Ap and OT leads, respectively (ns). R‐wave amplitudes at Ap versus OT were 23 ± 13 mV versus 14 ± 8 mV (n = 36, P < 0.001). R‐wave amplitudes at the Ap remained stable between implant and M7. R‐wave amplitudes at the OT could not be measured after implantation. In two patients, atrioventricular block occurred during active fixation at the OT. Conduction recovered spontaneously within 4 months. Ventricular fibrillation was induced in one patient during manipulation of an Ap lead in the RV. Marked differences were found between leads positioned in the OT versus Ap, partly related to the difference in lead design. Mean R‐wave amplitude was higher at the Ap that at the OT. Ease and success rate of lead implant was similar in both positions.
Microvolt T‐Wave Alternans During Exercise and Pacing in Patients with Acute Myocardial Infarction
Authors: RAATIKAINEN M.J. PEKKA , JOKINEN VESA , VIRTANEN VESA , HARTIKAINEN JUHA , HEDMAN ANTTI , HUIKURI HEIKKI V. ,   CARISMA INVESTIGATORS
Published: January 2005

Cardiac Arrhythmias and Risk Stratification after Myocardial infarction (CARISMA) is a prospective multicenter trial designed to document the incidence of cardiac arrhythmias after acute myocardial infarction (AMI), and to assess the predictive accuracy of various arrhythmic risk markers. In this substudy of the CARISMA trial, microvolt T‐wave alternans (TWA) was assessed with specific equipment 6 weeks after AMI during bicycle exercise, atrial (A) pacing, and simultaneous ventricular and atrial (V + A) pacing in 80 patients with left ventricular ejection fraction (LVEF) <40%. The agreement between the acute test results was determined by overall proportion of concordance and the kappa statistic. Sustained TWA was observed in 24, 45, and 50% of the patients during the exercise test, A pacing, and V + A pacing, respectively. The number of indeterminate TWA was significantly lower during V + A pacing (n = 7) than exercise test (n = 34). The TWA concordance rate was 71% between exercise and V + A pacing (κ= 0.53, P = 0.001), 79% between exercise and A pacing (κ= 0.54, P < 0.001), and 95% between the two pacing modes (κ= 0.89, P < 0.001). Patients with positive TWA in all tests had lower LVEF (28 ± 7% vs 35 ± 9%, P < 0.01) and wider QT dispersion (99 ± 44 ms vs 67 ± 38 ms, P < 0.01) than those with inconsistent test result. The low number of indeterminate tests and high concordance between the test results indicate that V + A pacing may provide a valuable means to assess TWA in patients who cannot complete the exercise test.
Dual effect of melatonin as proinflammatory and antioxidant in collagen‐induced arthritis in rats
Authors: Jiménez‐Caliani Antonio J. , Jiménez‐Jorge Silvia , Molinero Patrocinio , Guerrero Juan M. , Fernández‐Santos Jose M. , Martín‐Lacave Inés , Osuna Carmen
Published: January 2005

Abstract:  The aim of this study was to determine the effects of melatonin on proinflammatory status of rats with collagen‐induced arthritis (CIA). CIA was induced in male Wistar rats with an emulsion of type II collagen in Freund's Incomplete Adjuvant (C‐II/FIA). For 14 days, control and pinealectomized rats received a subcutaneous injection of 100 μL melatonin (30 μg) or vehicle (saline on 1% ethanol). Levels of cytokines interleukin (IL)‐1β and IL‐6 were determined in the serum, peripheral blood mononuclear cells, and joints. Levels of anti‐type II collagen antibody, nitrite/nitrate, and lipid peroxidation (LPO) were determined in the serum, joints, and brain. Treatment with melatonin significantly increased the levels of IL‐1β, IL‐6, nitrite/nitrate and LPO in joints. However, melatonin significantly reduced the levels of nitrite/nitrate and LPO in serum and brain. Moreover, CIA in pinealectomized rats presented significantly reduced levels of IL‐1β and IL‐6, titers of anti‐type II collagen antibodies, levels of nitrite/nitrate, and LPO in joints but elevated levels in serum and brain. Melatonin has been described as a proinflammatory and antioxidant agent. In a process of inflammation as CIA, melatonin acts with a markedly proinflammatory effect at local and peripheral levels maintaining its antioxidant effect only at peripheral level.
Inhibition of 5‐aminolevulinic acid‐induced DNA damage by melatonin, N1‐acetyl‐N2‐formyl‐5‐methoxykynuramine, quercetin or resveratrol
Authors: Onuki Janice , Almeida Eduardo A. , Medeiros Marisa H. G. , Mascio Paolo Di
Published: January 2005

Abstract:  Porphyrias are defined as either inborn or acquired diseases related to enzymatic deficiencies in the heme biosynthetic pathway. Lead poisoning, hereditary tyrosinemia, and acute intermittent porphyria (AIP) are characterized by the absence of photosensitivity and the accumulation of 5‐aminolevulinic acid (ALA) together with its increased urinary excretion. The main clinical manifestations of AIP are intermittent attacks of abdominal pain, neuromuscular weaknesses and neuropsychiatry alterations, and also an association with primary liver cancer, in which may be involved the oxidative potential of ALA which is able to cause DNA damage. The use of antioxidants in the treatment of ALA‐induced oxidative stress is not well established. In the current work, we show the antioxidant efficacy of several compounds including melatonin, quercetin, resveratrol and N1‐acetyl‐N2‐formyl‐5‐methoxykynuramine (AFMK), a melatonin oxidation product, in terms of their ability to limit DNA damage induced by ALA/Fe2+ in an in vitro system. Damage was measured by plasmid DNA strand breaks and detection of 8‐oxo, 7‐8‐dihydro,2′‐deoxyguanosine (8‐oxodGuo) by high‐performance liquid chromatography coupled with electrochemical detection. All compounds tested showed a dose‐dependent protective action against free radical damage. These results could be the first step toward studies of the possible use of these antioxidants in oxidative stress promoted by ALA or other pro‐oxidants.
Posthatching developmental changes in noradrenaline content in the chicken pineal gland
Authors: Zawilska Jolanta B. , Berezińska Małgorzata , Stasikowska Olga , Lorenc Anna , Skene Debra J. , Nowak Jerzy Z.
Published: January 2005

Abstract:  Noradrenaline (NA) levels in pineal gland of chickens at various posthatching stages (P2, P4, P8, P15, P30 and P57) were determined by high‐performance liquid chromatography with electrochemical detection. Pineal NA content markedly increased between P2 and P30. P30 and P57 chickens, kept from the day of hatching under a 12:12 hr light‐dark (LD) illumination cycle, exhibited rhythmic changes in pineal NA, with levels in the dark period being markedly higher than in the light period. In younger birds pineal NA concentrations did not show pronounced daily variations. In 4‐wk‐old chickens (P28–30) kept under constant darkness (DD), the rhythmic pattern of pineal NA persisted for 1 day (with higher values during the subjective dark phase than during the subjective light phase), but this disappeared 24 hr after the introduction of DD. In contrast, NA content in pineal glands isolated from birds maintained for 2 days under continuous light was similar to that found during the light phase of the LD cycle, and did not exhibit significant rhythmicity. In P30 chickens, pretreated with α‐methyl‐p‐tyrosine (AMPT, an inhibitor of tyrosine hydroxylase, the key regulatory enzyme in the biosynthesis of catecholamines), pineal NA content declined slowly and monophasically during the light phase. During the dark phase the AMPT‐induced decay of NA was biphasic – namely an initial rapid decline over the first 15 min which was followed by a slow‐rate decline – an observation indicating that NA turnover was higher in the dark. Acute exposure of the dark‐adapted P30 and P57 chickens to light significantly decreased pineal NA content, but did not affect pineal NA concentrations in younger birds. Our results suggest that the NA rhythm in the chicken pineal gland and its sensitivity to light regulation progressively develop during the first month of life.
Melatonin counteracts oxidative stress in rats fed an ochratoxin A contaminated diet
Authors: Abdel‐Wahhab Mosaad A. , Abdel‐Galil Mona M. , El‐Lithey Mohey
Published: January 2005

Abstract:  The mycotoxin ochratoxin A (OTA) is a widespread contaminant in human and animal food products. It induces a wide range of toxic effects including lipid peroxidation through the generation of free radicals. The aim of this work was to evaluate the antioxidant effects of melatonin against OTA‐induced oxidative stress in liver and kidney in rats. Treated animals were fed OTA‐contaminated diet (3 mg/kg) for 15 days before, during and after melatonin administration (20 mg/kg bw). The results indicate that OTA caused severe effects typical to those reported in the literature for ochratoxicosis. Melatonin alone was effective in the improving food intake, body weight gain, serum total protein, albumin, the activities of alkaline phosphatase, G‐glutamyl transferase and creatinine kinase and liver and kidney glutathione peroxidase, superoxide dismutase and malondialdehyde. Rats fed OTA‐contaminated diet before, during or after melatonin administration showed a significant improvement in all tested parameters toward the normal values of the controls. This improvement was most pronounced in the group pretreated with melatonin. It is concluded that melatonin exhibits a preventive effect against OTA‐induced oxidative stress through its role in the scavenging of free radicals and/or the prevention of lipid peroxidation.
Efficacy of Trimedoxime in Mice Poisoned with Dichlorvos, Heptenophos or Monocrotophos
Authors: Antonijević Biljana , Bokonjić Dubravko , Stojiljković Miloš P. , Kilibarda Vesna , Milovanovi Zoran A. , Nedeljkovi Mirjana , Maksimovi Matej
Published: January 2005

Abstract: The aim of the study was to examine antidotal potency of trimedoxime in mice poisoned with three direct dimethoxy‐substituted organophosphorus inhibitors. In order to assess the protective efficacy of trimedoxime against dichlorvos, heptenophos or monocrotophos, median effective doses and efficacy half‐times were calculated. Trimedoxime (24 mg/kg intravenously) was injected 5 min. before 1.3 LD50 intravenously of poisons. Activities of brain, diaphragmal and erythrocyte acetylcholinesterase, as well as of plasma carboxylesterases were determined at different time intervals (10, 40 and 60 min.) after administration of the antidotes. Protective effect of trimedoxime decreased according to the following order: monocrotophos > heptenophos > dichlorvos. Administration of the oxime produced a significant reactivation of central and peripheral acetylcholinesterase inhibited with dichlorvos and heptenophos, with the exception of erythrocyte acetylcholinesterase inhibited by heptenophos. Surprisingly, trimedoxime did not induce reactivation of monocrotophos‐inhibited acetylcholinesterase in any of the tissues tested. These organophosphorus compounds produced a significant inhibition of plasma carboxylesterase activity, while administration of trimedoxime led to regeneration of the enzyme activity. The same dose of trimedoxime assured survival of experimental animals poisoned by all three organophosphorus compounds, although the biochemical findings were quite different.
Electrical and optical properties of GaCrN films grown by molecular beam epitaxy
Authors: Polyakov A. Y. , Smirnov N. B. , Govorkov A. V. , Thaler G. T. , Frazier R. M. , Abernathy C. R. , Pearton S. J.
Published: January 2005

High concentrations of Cr (3–5at.%) were incorporated into GaN during molecular beam epitaxy. There was no evidence of significant formation of deep midgap states due to substitutional Cr acceptors. The results of optical absorption measurements and microcathodoluminescence measurements point to formation of a proper solid solution with the band gap lower than undoped GaN. GaCrN shows n-type conductivity. Increasing the Cr concentration increases the electrical resistivity, leads to a stronger optical absorption in the above-band-gap region, enhances the intensity of the yellow band near 2.3eV, and promotes the formation of electron traps with the activation energy of 0.2eV.
Thermal oxidation of Si1−x−yGexCy epitaxial layers characterized by Raman and infrared spectroscopies
Authors: Cuadras A. , Garrido B. , Morante J. R. , Hunt C. E. , Robinson McD
Published: January 2005

Thermal dry oxidation of Si1−x−yGexCy epilayers, over a wide range of compositions (0<x<0.6 and 0<y<0.05), is studied to assess the feasibility of its integration into silicon processes. It is found that differing oxidation conditions, with different x and y values, result in measurably different final amounts of Ge segregation and stress in the resultant oxides. Raman and infrared spectroscopies have been used to characterize the influence of oxidation conditions on the oxide and on the epilayer properties. It is found that a linear relationship exists between Raman shifts and C concentration in the epilayer. It is also found that the Raman band related to Si–Si bonds splits into two peaks. This double-peak structure is attributed to the development of a region closest to the oxide/epilayer interfaces which is enriched with Ge due to its rejection from the oxidation front. It is concluded that oxidation temperatures lower than 900°C will more readily avoid this segregation, whereas oxidations at higher temperatures, for shorter times, are better suited to minimize the effects of strain generated during the processing.
Deposition of diamond-like carbon film on phase-change optical disk by PECVD
Authors: Ueng H. Y. , Guo C. T.
Published: January 2005

With development of optical recording media oriented toward high-density optical systems, the protection of data storage becomes very critical. In this article, we report on the diamond-like carbon (DLC) films deposited by plasma-enhanced chemical vapor deposition on the polycarbonate (PC) substrate of phase-change optical recording disks. The mixed SiH4 in CH4∕H2 gases were used to reduce the internal compressive stress of the deposited films. The structural characteristics of the DLC films were analyzed as a function of film thickness by Raman spectroscopy. The variations of the G peak positions and the intensity ratio, ID∕IG, were investigated as a function of the DLC film thicknesses. The DLC film thickness is a very important characteristic related to the surface microroughness and transmittance. Several tests, including a tape pull test, a thermal shock test, and an alcohol rub test, were used to evaluate the adhesion of the DLC coatings on the PC substrates. The rms roughness and morphology of DLC films were inspected by an atomic force microscope. The dependence of optical transmittance, reflectivity, and the overwriting characteristics of jitter on the thickness of DLC films were investigated. Finally, our results indicate that DLC films can provide an effective capability for protecting stored data and exhibit a smooth enough surface and high transparency quality for the recording and overwriting characteristics of phase-change optical disks.
Fabrication technique for microelectromechanical systems vertical comb-drive actuators on a monolithic silicon substrate
Authors: Zhang Q. X. , Liu A. Q. , Li J. , Yu A. B.
Published: January 2005

This article presents a technique to fabricate a microelectromechanical systems vertical comb-drive actuator on a monolithic silicon substrate. This technique employs only two photomasks. The first photomask defines all the critical patterns, including a set of movable upper hollow comb fingers, a set of fixed lower comb fingers, and a suspension spring to avoid the alignment problem and maintain a small finger gap. The second photomask selectively covers the upper fingers to obtain the released upper hollow fingers. The vertical comb-drive actuator is fabricated by deep reactive ion etching process on a monolithic silicon wafer using these uniquely designed photomasks to avoid the residual stress and stiction problems. Different lateral gaps between the adjacent lower solid and upper hollow fingers are obtained with various finger widths. The height of the comb fingers is 10.0 μm. The vertical offset between the two sets of comb fingers can be adjusted by controlling the process conditions. Both symmetric and asymmetric staggered comb-drives are achieved through process modifications. The mechanism of notching effect is discussed and addressed by multiple spacer oxide deposition. Silicon residue effect, which occurs during the lowering down etching process, is investigated from the fabrication aspect and resolved by combining isotropic and anisotropic etching processes. This kind of vertical comb-drive actuator can be widely applied in optical switches, scanning micromirrors, and sensors.
Sidewall profile control of thick benzocyclobutene reactively ion etched in CF4∕O2 plasmas
Authors: Buchwald Walter R. , Vaccaro Kenneth
Published: January 2005

The feasibility of controlling the sidewall angle of thick benzocyclobutene (BCB) etched in a CF4∕O2 plasma using thick photoresist as an etch mask has been investigated. Sidewall angle, BCB etch rate, and BCB to photoresist selectivity as functions of chamber pressure and CF4 to O2 ratios are reported. Through the use of postdeveloped reflown photoresist, an optimum sidewall angle of less than 60° was achieved at 33mT chamber pressure and a 19% CF4∕O2 ratio. The method presented here achieves deep, residue-free etching of thick BCB with a sidewall profile suitable for e-beam evaporated and lifted metal for use in vertical interconnects.
Use of 370nm UV light for selective-area fibroblast cell growth
Authors: Kang B. S. , Ren F. , Jeong B. S. , Kwon Y. W. , Baik K. H. , Norton D. P. , Pearton S. J.
Published: January 2005

We have studied the effect of 370nm UV light on fibroblast cell growth. At this wavelength, the UV light produced a strong inhibition of the cell growth. By employing a thin TiO2 film on the glass template for cell growth, most of the UV light was reflected from the substrate and allowed the cells to grow. The TiO2 thin film can be patterned with standard photolithography followed by etching. Employing this technique, a 4μm resolution of patterned cell growth was achieved. Based on the simulation results using TiO2∕SiO2 mirror stacks, 99.5% of UV light can be reflected from the TiO2∕SiO2 coated area, and even higher resolution and a lower intensity of UV light for selective-area cell growth can be achieved.
Process integration compatibility of low-k and ultra-low-k dielectrics
Authors: Moore Darren , Carter Richard , Cui Hao , Burke Peter , McGrath Peter , Gu S. Q. , Gidley David , Peng Huagen
Published: January 2005

Damage of plasma-enhanced chemical vapor deposited SiOCH films on exposure to typical plasma etch, plasma ash and wet clean processes are investigated. Dielectrics of k=3.0, 2.5, and 2.2 show little film damage with standard fluorine chemistry plasma etch, but experience severe film degradation on exposure to a typical oxygen plasma ash, used to remove photoresist. Effects of film damage on exposure to oxidative plasma ash include film densification, Si-OH formation, water adsorption, and dielectric constant increases. Theses effects are found to be more severe for the higher porosity, lower-k films, and are unrecoverable with thermal anneal.
Determination of spatial resolution in atomic-force-microscopy-based electrical characterization techniques using quantum well structures
Authors: Douhéret O. , Bonsels S. , Anand S.
Published: January 2005

In this work, a procedure to determine the spatial resolution in scanning capacitance (SCM) and scanning spreading resistance microscopy (SSRM) is proposed and demonstrated. It is based on profiling of confined carriers (in cross section) in quantum well (QW) structures consisting of QWs with different well widths and interwell spacing. Spatial resolution of sub-5 nm was observed for SSRM with commercially available diamond-coated silicon probes and sub-30 nm for SCM with IrPt5-coated probes. The influence of experimental parameters such as tip–sample bias and tip averaging on lateral resolution is discussed and appropriate measurement conditions for performing high-resolution measurements are highlighted. Finally, it is proposed that such structures can be used not only to select probes appropriate for high resolution measurements, but also in the development of new probes.
Predicting surface figure in diamond turned calcium fluoride using in-process force measurement
Authors: Marsh Eric R. , John Binu P. , Couey Jeremiah A. , Wang Jue , Grejda Robert D. , Vallance R. Ryan
Published: January 2005

Single crystal calcium fluoride (CaF2) shows significant variation in material properties as a function of crystallographic orientation. The surfaces generated by material removal processes such as diamond turning are influenced by this anisotropy and consequently show periodic undulations aligned with the crystal structure. This article explores the relationship between surface figure and cutting forces measured during the diamond turning of single crystal calcium fluoride. The cutting forces, when mapped to the physical geometry of CaF2 plano (flat) optics, show good correlation with surface figure measured by interferometry. A model is presented to predict the surface figure error from the experimentally measured normal component of the cutting force. The model also shows how the surface figure obtained under various machining parameters may be extrapolated from force measurements made during a single diamond turning operation.
Scanning spreading resistance microscopy of two-dimensional diffusion of boron implanted in free-standing silicon nanostructures
Authors: Kluth S. M. , Álvarez D. , Trellenkamp St. , Moers J. , Mantl S. , Kretz J. , Vandervorst W.
Published: January 2005

B implants of 1keV, 1×1015at.cm−2 into 125-nm-wide, free-standing Si nanostructures have been characterized using scanning spreading resistance microscopy following a 0s, 1050°C anneal in N2. A curved diffusion front has been observed. B in the center of the ridge diffuses further than at the sides. A similar effect has been observed in SUPREM-IV simulations. It is attributed to a reduction in transient enhanced diffusion close to the vertical surfaces due to recombination of ion-implantation-induced excess Si self-interstitials.
Anodic bonding using the low expansion glass ceramic Zerodur®
Authors: van Elp J. , Giesen P. T. M. , van der Velde J. J.
Published: January 2005

Using anodic bonding, a strong bond has been created between the ultralow expansion glass ceramic Zerodur® from Schott and an Al coated piece of ultralow expansion glass (ULE® from Corning). The bond strength has been tested using a tensile testing machine. The bond strength is comparable to the fracture strength of the ULE® material. Using anodic bonding it will be possible to make complicated electrostatic clamps for the next generation lithography machines based on an all ultralow expansion design.