bluuebunny/crossref_metadata_2025 huggingface dataset:
Cerebral Syncope: Loss of Consciousness Associated with Cerebral Vasoconstriction in the Absence of Systemic Hypotension
Authors: GRUBB BLAIR P. , SAMOIL DANIELA , KOSINSKI DANIEL , WOLFE DOUGLAS , BREWSTER PAMELA , ELLIOTT LAURA , HAHN HARRY
Published: July 2006

Transcranial Doppler (TCD) ultrasonography done during headupright tilt induced neurocardiogenic syncope has demonstrated that cerebral Vasoconstriction occurs concomitant with (or precedes) loss of consciousness. This article demonstrates evidence that cerebral blood flow changes alone (vasoconstriction), in the absence of systemic hypotension, may result in syncope. Five patients (4 men, 1 woman; mean age 41 ± 17 years) with recurrent unexplained syncope were evaluated by use of an upright tilt table test for 45 minutes with or without an infusion of low dose isoproterenol. TCDoppler ultrasonography was used to assess middle cerebral artery systolic velocity (Vs); diastolic velocity (Vd); mean velocity (Vm); and pulsatility index (PI = Vs = Vd/Vmean). Syncope occurred in five patients during the baseline tilt and in one patient during isoproterenol infusion. During tilt induced syncope, at an average mean arterial pressure of 89 ± 16 mmHg, TCD sonography showed a 2%± 10% increase in systolic velocity; a 51%± 27% decrease in diastolic velocity; and a 131 %± 87% increase in pulsatility index. One patient underwent continuous electroencephalographic recording during tilt, which demonstrated diffuse slow wave activity (indicating cerebral hypoxia) at the time of syncope concomitant with the aforementioned TCD changes in the absence of systemic hypotension. These fndings reflect an increase in cerebrovascular resistance secondary to arteriolar vasoconstriction distal to the insonation point of the middle cerebral artery, that occurred concomitant with loss of consciousness and in the absence of systemic hypotension. We conclude that in some individuals abnormal baroreceptor responses triggered during orthostatic stress may result in a derangement of cerebral autoregulation leading to cerebral vasoconstriction with resultant cerebral hypoxia in the absence of systemic hypotension.
Acute Effects of Radiofrequency Ablation upon Atrial Conduction in Proximity to the Lesion Site
Authors: CHORRO FRANCISCO J. , SANCHIS JUAN , SUCH LUIS , GARCÍA‐CIVERA ROBERTO , LLAVADOR ESTEBAN , MAINAR LUIS , CÁNOVES JOAQUÍN , EGEA SANTIAGO , CERDÁ MIGUEL , LÓPEZ‐MERINO VICENTE
Published: July 2006

The electrophysiological effects of RF ablation upon the areas in proximity to the lesioned zones have not yet been well characterized. An experimental model is used to investigate atrial conduction in the boundaries of RF damaged zones. In 11 isolated and perfused rabbit hearts, endocardial atrial electrograms were recorded using an 80‐Iead multiple electrode positioned in the left atrium. Both before and after the RF application (5 W, 8 s, 1‐mm diameter unipolar epicardial electrode) in the mid‐portion of the free left atrial wall, measurements were made of conduction time from the pacing zone (posterior wall of the left atrium) to three points between 7.5 and 7.9 mm distal to the damaged zone. Conduction velocity and the direction of the activation propagation vector were determined in ten groups of four electrodes positioned around the damaged zone, and at the left atrial appendage. The mean diameter (± SEM) of the transmural lesions produced by RF ablation and defined by macroscopic examination was 4.2 ± 0.2 mm. The conduction times to the three points distal to the lesion site were significantly prolonged as a result of RF ablation: 7.6 ± 0.4, 7.4 ± 0.5, and 6.9 ± 1.0 ms (control); and 11.3 ± 1.0 (P ≤ 0.01), 11.1 ± 1.3 (P < 0.01), 10.6 ± 1.4 ms (P < 0.05) (post‐RF). The differences between the conduction velocities determined in the areas surrounding the lesion, before and after RF application, failed to reach statistical significance: 86.2 ± 6.5 cm/s (control) versus 75.5 ± 5.7 cm/s (post‐RF) (NS). After RF, significant variations were only observed in the direction of impulse propagation in the proximal‐inferior quadrant adjacent to the lesion site, the difference being ‐61°± 18° (P < 0.02). In 2 of 4 experiments in which the lesion size was increased by a second RF application (5 W, 16 s), tachycardias with activation sequence around the lesion could be induced, with cycle lengths of 56 and 50 ms, respectively. In the atrial wall, the conduction times to the regions distal to the RF lesion are significantly prolonged. No significant changes are observed in conduction velocity in the areas in proximity to the lesion. Prolonged conduction to the areas distal to the ablation site is due to the lengthened pathway traveled by the impulses in reaching these areas. Tachycardias with activation patterns that suggest reentry around the RF damaged zone may be induced.
Repetitive Ventricular Responses Induced by Radiofrequency Ablation for Idiopathic Ventricular Tachycardia Originating from the Outflow Tract of the Right Ventricle
Authors: CHINUSHI MASAOMI , AIZAWA YOSHIFUSA , OHHIRA KOUJI , FUJITA SATOSHI , SHIBA MASAMI , NIWANO SHINICHI , FURUSHIMA HIROSHI
Published: July 2006

In 23 consecutive patients, radiofrequency (RF) ablation was used as treatment for idiopathic ventricular tachycardia (VT) originating from the outflow tract of the right ventricle. In this study, we focused on the repetitive ventricular response (> 5 consecutive QRS beats during RF application). The incidence and clinical implications of the repetitive ventricular response were examined through the results of endocardial mapping and RF ablation. VT origin was mapped as the earliest activation site during VT, and it was determined within 0.5 × 0.5 cm (narrow site) in 13 patients and wider than 0.5 × 0.5 cm (wide origin) in the other 10 patients. The repetitive ventricular response was induced during application of RF current in 14 of 23 patients (61%), and it was more frequently observed in VT from a wide origin (100%) than in the VT from a narrow site (31%). The QRS morphology of the repetitive ventricular response was identical to that of clinical VT. As RF application was continued and/or repeated, the RR interval of the repetitive ventricular response was gradually prolonged, the number of consecutive QRS complexes was decreased, and clinical VT was finally eliminated. The overall success rate of RF ablation was 96% (22/23 patients), and no complications were observed. In conclusion, a repetitive ventricular response was frequently observed in idiopathic right VT. The changing pattern of repetitive ventricular response, slowing, and/or disappearing was consistent with successful RF ablation.
Relationship Between the Upper Limit of Vulnerability Determined in Normal Sinus Rhythm and the Defihrillation Threshold in Patients with Implantahle Cardioverter Defihrillators
Authors: HUI RICHARD C. , ROSENTHAL LARRY , RAMZA BRIAN , NSAH EMMANUEL , LAWRENCE JOHN , TOMASELLI CORDON , BERCER RONALD , CALKINS HUCH
Published: July 2006

The upper limit of vulnerability is the strength above which ventricular fibriilation is no Ionger inducible with a shock delivered during the vulnerable phase of the cardiac cycle. It has been demonstrated that the upper limit of vulnerability correlates with the defibrillation threshold in a paced rhythm. The purpose of this study is to evaluate the correlation of the upper limit of vulnerability determined in normal sinus rhythm with the defibrillation threshold using a simplified protocol in patients undergoing placement of an ICD. We studied 28 patients who underwent ICD implantation. CPI generators and Endotak leads were used in all patients. Device‐based testing was used to determine the defibrillation threshold and the upper limit of vulnerability. The upper limit of vulnerability was tested with three shocks delivered at 0, 20, and 40 ms before the peak of the T wave during normal sinus rhythm. The defibrillation threshold was determined by a simple step up‐down protocol. The upper limit of vulnerability (9.0 ± 4.5 f) did not significantly differ from the defibrillation threshold (9.9 ± 4.0 J), P = NS. A close correlation was present, correlation coefficient = 0.75. P < 0.0001. The upper limit of vulnerability was within 5 f of the defibrillation threshold in 27 (96%) of the 28 patients. The upper limit of vulnerability underestimated the defibrillation threshold by 10 f in one patient who had a defibrillation threshold of 15 J. The upper limit of vulnerability determined in normal sinus rhythm correlates significantly with the defibrillation threshoid in patients undergoing ICD implantation. The protocol is simple and easily implemented clinically.
Is the Atrial High Rate Episode Diagnostic Feature Reliahle in Detecting Paroxysmal Episodes of Atrial Tachyarrhythmias?
Authors: SEIDL KARLHEINZ , MEISEL ECKARD , VANAGT EDDY , OTTENHOFF FRANS , HESS MIKE , HAUER BERND , ZAHN RALF , SENGES JOCHEN
Published: July 2006

The atrial high rate episode diagnostic in The Thera® pacemaker reports frequency, duration, and date/time of atrial tachyarrbytbmias according to programmed criteria. The aim of The study was to validate The atrial high rate episode diagnostic feature. Episodes of atrial fibrillation recorded by Holter monitoring were compared to episodes detected by the pacemaker. Eorty five ambulatory (Holter) recordings were used for evaluation. Thirty of 45 ambulatory (Holter) recordings showed sinus rhythm. On 4 of these 30 ambulatory (Holter) recordings, The Thera® detected 12 episodes of atrial tachyarrbythmias as false‐positives (sinus rhythm was detected as atrial tacbyarrbytbmia). The main reason was far‐field R and T wave oversensing. On 15 of 45 ambulatory (Holter) recordings, 125 episodes of atrial tachyarrhytbmias were recorded. Ninety‐three of these events also were detected by the pacemaker, while for 32 events the Thera® reported sinus rhythm. The main reason was that the episodes were of too short duration. Therefore, the Thera® (programmed with detection rate 160 beats/min, detection beats 40, termination beats 10) was unable to detect atrial tachycardias. Software simulation of The diagnostic algorithm under several programming settings using the digitized Holter files demonstrated highly reliable detection of atrial tachyarrhythmias (sensitivity 98%, specificity 100%) when programmed as follows: detection rate 220 beats/min, detection beats 10, termination beats 20. It can be concluded that Thera®'s high rate episode monitor is a reliable tool for detection of a trial tachyarrhythmias, if programmed as recommended.
Circadian Variations in Minute Ventilation Can Be Reproduced by a Pacemaker Sensor
Authors: BONNET JEAN‐LUC , VAI FRANÇOIS , PIOGER GUY , GARRIGUE STEPHANE , CLEMENTY JACQUES , CAZEAU SERCE
Published: July 2006

Special software allowing the memorization of 24‐hour minute ventilation can be loaded into the memoiy of the Chorus RM, a DDDR pacemaker driven by minute ventilation. This feature was tested in the postimplant period in 13 patients. Measurements of minute ventiiation, respiratory rate, and respiratory amplitude were analyzed according to prospectively defined diurnal and nocturnal time periods. Minute ventilation decreased by 39% (P < 0.001) from the diurnal to the nocturnal phase, while respiratory rate and amplitude decreased by 18% and 28%, respectively (P < 0.001 each). Thus, minute ventilation allowed discrimination between sleep and waking hours. This information could be utilized to modulate the backup rate of the pacemaker.
Microwave Catheter Ablation Using a Clinical Prototype System with a Lateral Firing Antenna Design
Authors: LIEM L. BING , MEAD R. HARDWIN , SHENASA MOHAMMAD , CHUN SUNG , HAYASE MOTOYA , KERNOFF ROBERT
Published: July 2006

Microwave has been considered a potentially more effective and more versatile form of energy than radiofrequency. Its feasibility has been tested using various prototype systems and catheter designs. This study assessed the safety and efficacy of a clinically‐suitable prototype microwave power supply and catheter system with a lateral‐firing antenna design for atrioventricular (AV) junction ahlation in canines and to correlate with tissue histopathology. The system consisted of a deflectable catheter with a 6‐mm antenna and a thermocouple; and a 2.45‐CHz frequency generator with power, time, and temperature controls. AV junction ablations were performed using 75 W energy for up to 60 seconds. Effective heating was confirmed hy a rise in catheter temperature to 69.3 ± 8.8°C. Complete AV nodal block was accomplished in all canines after an average of 4.1 ± 2.3 applications at 66.8 ± 7.7°C, and persisted after 28 days in all chronic animals. Lesions were consistent with thermal necrosis, were hemispherical to semi linear in shape and have distinct borders. Acute lesions were 3.4 ± 1.5 mm wide, 4.8 ±2.1 long, and 2.0 ± 0.9 deep. Chronic lesions showed typical healing and were smaller in size. Ablations did not cause any transvalvular, vascular or other cardiac structural damage, and no coagulum formation was noted on the antenna or catheter tip. Microwave AV junction ablation using this clinical prototype system specifically designed for it was safe and effective. Lesion's depth was limited to 5 mm with 60‐second heating while its shape corresponded to the antenna's length. Microwave energy may provide greater versatility for producing discrete or linear ablation.
Failure of Third‐Generation Implantable Cardioverter Defibrillators to Abort Shock Therapy for onsustained Ventricular Tachycardia Due to Shortcomings of the VF Confirmation Algorithm
Authors: GRIMM WOLFRAM , MENZ VOLKER , HOFFMANN JÜRGEN , MAISCH BERNHARD
Published: July 2006

Unnecessary shocks by ICDs for rhythms other than sustained VT or VF have been described as the most frequent adverse event in ICD patients. To avoid unnecessary shocks for self‐terminating arrhythmias, the third‐generation Jewel PCD defibrillators 7202, 7219, and 7220 Plus use a specially designed VF confirmation algorithm after charge end. The purpose of this study was to determine the ability of this VF confirmation algorithm to recognize nonsustained VT, and to analyze the reasons for failure of the PCD device to abort shock therapy for nonsustained VT despite use of this VF confirmation algorithm. Analysis of stored electrograms of electrical events triggering high voltage capacitor charging in the programmed VF zone of the device showed 36 spontaneous episodes of nonsustained VT (227 ± 21 beats/mm) during 18 ± 7 months follow‐up in 15 patients who had a Jewel PCD implanted at our hospital. Intracardiac electrogram recordings and simultaneously retrieved marker channels demonstrated that the ICD shock was appropriately aborted according to the VF confirmation algorithm in 24 (67%) of 36 episodes of nonsustained VT. Twelve episodes (33%) of nonsustained VT, however, were followed by a spontaneous ICD shock in 6 (40%) of the 15 study patients. The only reason for all 12 shocks for nonsustained VT was the inability of the device to recognize the absence of VT after charge end due to shortcomings of the VF confirmation algorithm: 11 of the 12 shocks for nonsustained VT were triggered by the occurrence of paced beats during the VF confirmation period and 1 shock for nonsustained VT was triggered by the occurrence of 2 premature beats after charge end. Thus, better VF confirmation algorithms need to be incorporated in future PCD devices to avoid unnecessary shocks for nonsustained VT.
Radiofrequency Ablation of Anteroseptal, Para‐Hisian, and Mid‐Septal Accessory Pathways Using a Simplified Femoral Approach
Authors: MARTÍPUIGFEL JOSEP BRUGADA. , MONT LLUÍS , BOLAO IGNACIO GARCÍA , FIGUEIREDO MARCIO , MATAS MARIONA , NAVARRO‐LÓPEZ FRANCISCO
Published: July 2006

Feasibility of RF ablation using a simplified two‐catheter technique from a femoral approach was studied in 97 consecutive patients with a manifest or concealed accessory pathway located at the anteroseptal, mid‐septal, and para‐Hisian areas. BF was applied at the site with the shortest V‐delta interval or the earliest retrograde atrial activation during orthodromic tachycardia or right ventricular pacing. Ablation was initially successful in 88 of’97 patients (91 %). Success rate was 94% (16/17) for anteroseptal. 94% (39/43] for para‐Hisian, and 89% (33/37) for mid‐septal accessory pathways, without differences between manifest and concealed pathways for any of the locations. Mean number of BF pulses was 8 ± 5 for anteroseptal, 6 ± 6 for mid‐septal, and 12 ± 13 for para‐Hisian accessory pathways. Two patients (2%) required implantation of a permanent pacemaker for complete A V block. At a mean follow‐up of 27 ± 14 months, four patients with previous manifest preexcitation experienced resumption of intermittent preexcitation, but only one required a second successful procedure for recurrence of palpitations. RF ablation can be used effectively and without impairment of normal AV conduction in the majority of patients with anteroseptal, para‐Hisian, and mid‐septal accessory pathways using a simplified two‐catheter technique from a femoral approach.
Atrial Dissociation After Atrial Compartment Operation for Chronic Atrial Fibrillation in Mitral Valve Disease
Authors: LI YI‐HENG , LO HUEY‐MING , LIN FANG‐YUE , LIN JIUNN‐LEE , LIEN WEN‐PIN
Published: July 2006

Atrial dissociation with segmental atrial arrhythmia is an interesting electrophysiological phenomenon. It was rarely reported before to be caused by anatomical exit block after cardiac surgery. We report the case of a 28‐year‐old patient who developed atrial dissociation after a surgical method for correcting atrial fibrillation—atrial compartment operation. The segmental atrial flutter was first found by Doppler echocardiography and proved later by detailed intracardiac mapping.
Incessant Fascicular Tachycardia: A Cause of Arrhythmia Induced Cardiomyopathy
Authors: ANSELME* FREDERIC , BOYLE NOEL , JOSEPHSON MARK
Published: July 2006

An incessant ventricular tachycardia arising from the posterior fascicle is reported in a 29‐yearold woman. This fascicular tachycardia was due to triggered activity and was clinically induced by an underlying paroxysmal atrial fibrillation. The initial echocardiographic evaluation revealed biventricular dysfunction with an ejection fraction of 30%. On propranolol, the patient has remained asymptomatic and the ventricular function has become normal after 3 months free of arrhythmia.
Electrocardiographic and Clinical Predictors of Torsades de Pointes Induced by Almokalant Infusion in Patients with Chronic Atrial Fibrillation or Flutter: A Prospective Study
Authors: HOULTZ BIRGITTA , DARPÖ BÖRJE , EDVARDSSON NILS , BLOMSTRÖM PER , BRACHMANN JOHANNES , CRIJNS HARRY J.G.M. , JENSEN STEEN M. , SVERNHAGE ELISABETH , VALLIN HANS , SWEDBERG KARL
Published: July 2006

The aim of this study was to identify predictors of torsades de pointes (TdP) in patients with atrial fibrillation (AF) or flutter exposed to the Class III antiarrhythmic drug almokalant. TdP can be caused by drugs that prolong myocardial repolarization. One hundred patients received almokalant infusion during AF (infusion 1) and 62 of the patients during sinus rhythm (SR) on the following day (infusion 2). Thirty‐two patients converted to SR. Six patients developed TdP. During AF, T wave alternans was more common prior to infusion (baseline) in patients developing TdP (50% vs 4%, P < 0.01). After 30 minutes of infusion 1, the TdP patients exhibited a longer QT interval (493 ± 114 vs 443 ± 54 ms [mean ± SD], P < 0.01), a larger precordial QT dispersion (50 ± 74 vs 27 ± 26 ms, P < 0.05), and a lower T wave amplitude (0.12 ± 0.22 vs 0.24 ± 0.16 mV. P < 0.01). After 30 minutes of infusion 2, they exhibited a longer QT interval (672 ± 26 vs 489 ± 74 ms, P < 0.001), a larger QT dispersion in precordial (82 ± 7 vs 54 ± 52 ms, P < 0.01) and extremity leads (163 ± 0 vs 40 ± 34 ms, P < 0.001), and T wave alternans was more common (100% vs 0%, P < 0.001). Risk factors for development of TdP were at baseline: female gender, ventricular extrasystoles, and treatment with diuretics; and, after 30 minutes of infusion: sequential bilateral bundle branch block, ventricular extrasystoles in bigeminy, and a biphasic T wave. Patients developing TdP exhibited early during almokalant infusion a pronounced QT prolongation, increased QT dispersion, and marked morphological T wave changes.
Reproducibility of Tilt Table Testing in Patients With Vasovagal Syncope and Its Relation to Variations in Autonomic Nervous System Activity
Authors: KOCHIADAKIS GEORGE E. , KANOUPAKIS EMMANUEL M. , ROMBOLA AMALIA T. , IGOUMENIDIS NIKOS E. , CHLOUVERAKIS GREGORY I. , VARDAS PANOS E.
Published: July 2006

To assess the variability of head‐ up tilt table testing, 35 patients with vasovagal syncope, shown by a positive tilt table test, underwent a second test 1 week later. Also, on the day before each test, spectral and time‐domain indexes of heart rate variability were derived from Holter recordings to examine the stability of autonomous nervous system activity in these patients. Fifteen healthy volunteers served as a control group and also underwent two tilt table tests with prior Holter monitoring. Twenty‐one (60%) of the 35 patients had a second positive test. None of the patients in the control group experienced syncope during either of the tests. The heart rate variability measures in the control group varied slightly from 1 day to the other, in contrast to the syncopal patients, where only low frequency spectral power and the mean of all 5‐minute standard deviations of RR internals showed comparable behavior. The indexes which reflect parasympathetic activity exhibited significant fluctuations in the syncopal patients. These fluctuations were due entirely to the patients who did not reproduce the outcome of the tilt table test, where high parasympa‐thetic tone was associated with the positive test and normal parasympathetic tone with the negative test. In contrast, the patients with two positive tests had high parasympathetic tone during both test periods, with low individual variability. In conclusion, patients with vasovagal syncope show variations in vagal autonomic tone and appear to be more prone to syncope when their parasympathetic tone is elevated.
The Effect of Inducing Ventricular Fibrillation with 50‐Hz Pacing Versus T are Stimulation on the Ability to Defibrillate
Authors: MALKIN ROBERT A. , JOHNSON ERIC E.
Published: July 2006

When testing an ICD, there are at least two techniques for inducing ventricular fibrillation: (1) high frequency (∼ 50 Hz) pacing; and (2) a single T wave stimulus. It is generally assumed that these two methods yield similar results. This study directly tested this assumption. In six dogs, one defibrillation electrode was placed in the right ventricular (RV) apex and the second was placed cutaneously on the left thorax. All defibrillation and T wave stimuli were biphasic between these two electrodes. Pacing was monophasic from the tip of the RV catheter to the cutaneous patch. The voltage which defibrillates 50% of the time (DF50) was measured using a 10‐step Bayesian up‐down method. Observations for two DF50 measurements were randomly interleaved. For one DF50 measurement, fibrillation was induced with 99 pacing stimuli at a 20‐ms pacing interval (50‐Hz pacing). For the second DF50 measurement, fibrillation was induced with a single defibrillation shock of approximately ½ J delivered at a time corresponding to the peak of the T wave in the lead II electrogram (T wave stimuli). The average DF50 when measured after fibrillation induced with 50‐Hz pacing was 379 ± 54.6 V, as compared to 382 ± 50.3 V when fibrillation was induced with T wave stimuli. The difference of 3 V was not statistically significant. If these results are confirmed in humans, it is reasonable to assume that the efficacy of a defibrillation shock is the same whether T wave stimuli or 50‐Hz pacing are used to induce fibrillation.
Role of Transesophageal Echocardiography in the Diagnosis of Infected Retained Pacing Lead
Authors: BARBETSEAS JOHN , LALOS SPYROS , KYRIAKIDIS MICHAEL , AGGELI CONSTADINA , TOUTOUZAS PAVLOS
Published: July 2006

A 68‐year‐old woman had a tronsvenous pacemaker implanted 6 years ago. One year after the procedure the pulse generator was removed due to generator site infection. Efforts to remove the lead resulted in fracture of the tip, which was abandoned in the right cardiac cavities. After this the patient suffered intermittent episodes of fever and chills, which responded to antibiotic therapy. At her recent admission, transesophageal echocardiography revealed a large mass attached to the free end of the fractured lead suggestive of the existence of a vegetation on the pacing lead. The diagnosis was confirmed at surgery.
Unusual Approach of a Pacemaker Electrode in a Patient with a Silent Superior Vena Cava Syndrome
Authors: de COCK CAREL C. , STOOKER WIM , VISSER CEES A.
Published: July 2006

A man with a history of bilateral pectoral pocket infection and subsequent pacemaker implantation with a screw‐in epicardial lead was referred because of increasing lead impedance. Venography revealed bilateral total occlusion of the subclavian and innominate veins with extensive collateral formation in this asymptomatic patient. Both internal jugular veins were also totally occluded. Because repeated pacemaker implantation using epicardial leads resulted in increasing lead impedance of the ventricular lead within 1 year after implant, an alternative approach was found using the superior caval vein with minimal invasive thoracotomy for single lead VDD pacing.
Transiliac Vein Approach to a Permanent Pacemaker Implantation After Aortic Valve Reoperation
Authors: GOTO YOSHIKAZU , ABE TADAAKI , SEKINE SATOSHI , IIJIMA KEITAROU , KONDOH KATSUYUKI , MATSUKAWA MAKOTO
Published: July 2006

This article describes the case of a 71 ‐year‐old woman in whom a permanent pacemaker implantation was performed through an iliac vein because of superior vena cava obstruction after aortic valve reoperation. During a 6‐month follow‐up, the patient did well and the pacemaker performance was satisfactory.
Interrelations Between QRS Morphology, Duration, and HV Interval Changes Following Right Bundle Branch Radiofrequency Catheter Ablation
Authors: MEHDIRAD ALI AKBAR , CURTISS EDWARD , TCHOU PATRICK
Published: July 2006

Interrelations between QRS morphology, duration, and HV interval changes in a model of “complete” bundle branch block following right bundle branch radiofrequency ablation have not been subjected to systematic study. This article describes these interrelations in patients who underwent right bundle ablation. Over a period of 42 months, 16 patients underwent radiofrequency ablation of the right bundle for treatment of bundle branch reentrant tachycardia. AH 16 patients had prolonged HV interval at baseline (minimum = 60 ms; mean = 68 ± 8 ms). After ablation, one patient developed complete heart block; the remaining 15 patients developed complete right bundle branch block (RBBB) and further prolongation of the HV interval (increment = 24 ± 16 ms). In 14 of these 15 patients, QRS duration was 138 ± 26 ms before ablation and increased to 168 ± 13 ms after ablation. In the remaining patient, the QRS duration was 160 ms before ablation and shortened to 144 ms following ablation despite further HV prolongation. Larger increases of HV interval after ablation were associated with smaller or negative changes in QRS duration (r = ‐0.77). There was a direct relationship between QRS duration at baseline and the increment in HV interval after ablation (r = 0.70), and an inverse relationship between QRS duration before and after ablation (r = ‐0.84). Radiofrequency ablation of right bundle may he associated with an increase in HV interval and QRS duration. However, HV interval prolongation is not necessarily associated with QRS duration widening. A large change in HV interval is more likely to be associated with an already prolonged QRS duration before ablation and a lesser increase or even decrease in QRS duration after ablation. A shorter QRS duration before ablation is associated with a smaller HV interval increase following ablation but a greater increment in QRS duration. These findings are consistent with the concept that narrowness of QRS duration is due to synchronized activation of ventricular endocardium; whereas, QRS duration widening seen with His Purkinje damage is due to reduced synchronization of endocardial activation.
VDD Pacing in Persistent Left Superior Vena Cava
Authors: OKREGLICKI A.M. , MILLAR R.N. SCOTT
Published: July 2006

Although persistent left superior vena cava (PLSVC) is the most common major venous anomaly of the heart, associated absence of the right superior vena cava with normal visceral situs is exceedingly rare. Such a patient presented with complete heart block requiring permanent pacing. This was achieved successfully using a single lead VDD system via the PLSVC with atrial sensing in the coronary sinus.
Long‐Term Thrombosis after Transvenous Permanent Pacemaker Implantation
Authors: GOTO YOSHIKAZU , ABE TADAAKI , SEKINE SATOSHI , SAKURADA TOHRU
Published: July 2006

To assess the efficacy of prophylactic administration of anticoagulant and antiaggregant drugs to prevent venous thrombosis after long‐term transvenous permanent pacemaker implantation, venograms were performed in 100 consecutive patients at the elective replacement of the pacemaker. Mean follow‐up period after initial transvenous permanent pacemaker implantation was 6.0 years. The venograms demonstrated normal in 77 patients. The remaining 23 venograms showed venous stenosis in 11 patients and total obstruction in 12 patients. Twenty‐one of these 23 patients had venous collateral circulation. No difference was found in the incidence of venous abnormalities according to the route of entry, the lead insulation, the total number of the implanted leads, and anticoagulant and antiaggregant drugs. All these patients have remained asymptomatic. In conclusion, the incidence of venous thrombosis after long‐term transvenous pacing is 23% and the causes of venous thrombosis may be endothelial trauma and underlying venous stenosis. As this article describes a retrospective limited study, we cannot find the efficacy of prophylactic administration of anticoagulant and antiaggregant drugs to prevent venous thrombosis formation after transvenous permanent pacemaker implantation. Further prospective study will be needed to assess the efficacy of prophylactic administration of anticoagulant and antiaggregant drugs.
Psychosocial Outcome after ICD Implantation: A Current Perspective
Authors: HELLER STANLEY S. , ORMONT MARIAN A. , LIDAGOSTER LIDIA , SCIACCA ROBERT R. , STEINBERG JONATHAN S.
Published: July 2006

Depression and reduced sexual functioning have been identified as problems following ICD placement. We examined these issues, and multiple other quality‐of‐life measures, and their relationship to ICD and ICD discharge. Patients were 64 ± 11 years old, 72% male, and had undergone ICD 20 ± 14 months previously. Fifty‐eight patients responded to a confidential biopsychosocial questionnaire. Positive attitudes toward the procedure increased from 52% before to 76% after implantation. Satisfaction correlated most strongly with less anger (P = 0.002, r = 0.45), less worry about ICD size (P = 0.007, r = 0.38), less sadness (P = 0.01, r = 0.37), and perceived better health (P = 0.01, r = 0.35). Of these ICD patients, 20%–58% reported measures of depression, and sexual frequency was reduced in 45%. Despite successful ICD placement, health concern increased in 62 % of the respondents. Thirty‐nine percent attended support groups; 96% found them very helpful. Mean number of ICD discharges described by responders was 5 ± 11. Fifty percent of our sample reported ≥ 1 shock; equal numbers had 1, 2–5, 6–10, and more than 10 shocks. Sixty‐two percent of men had at least one discharge compared to 13% of women. After controlling for cardiac clinical variables, experiencing ≥ 1 ICD shock was strongly associated with anxiety about family (odds ratio = 7.3), reduced new activities (odds ratio = 6.9), increased sadness (odds ratio = 6.2), and health worry (odds ratio = 5.8). Experiencing ≥ 5 ICD shocks was strongly associated with increased health concern (odds ratio = 13.6), increased sadness (odds ratio = 12.5), increased fatigue (odds ratio = 6.1), current sadness (odds ratio = 5.8), and increased nervousness (odds ratio = 5.3). ICD implantation powerfully affects quality‐of‐life. Postimplantation health concern is paradoxically increased despite improvement in actual health. Negative emotions are associated with defibrillator discharge.
Effects of Respiration Phase on Ventricular Defibrillation Threshold in a Hot Can Electrode System
Authors: YAMANOUCHI YOSHIO , MOWREY KENT A. , KROLL MARK W. , BREWER JAMES E. , DONOHOO ANN M. , NIEBAUER MARK J. , WILKOFF BRUCE L. , TCHOU PATRICK J.
Published: July 2006

The impedance of defibrillation pathways is an important determinant of ventricular defibrillation efficacy. The hypothesis in this study was that the respiration phase (end‐inspiration versus end‐expiration) mayalter impedance and/or defibrillation efficacy in a “hot can” electrode system. Defibrillation threshold (DFT) parameters were evaluated at end‐expiration and at end‐inspiration phases in random order by a biphasic waveform in ten anesthetized pigs (body weight: 19.1 ±2.4 kg; heart weight: 97 ± 10g). Pigs were intubated with a cuffed endotracheal tube and ventilated through a Drager SAVrespirator with tidal volume of 400–500 mL. A transvenous defibrillation lead (6 cm long, 6.5 Fr) was inserted into the right ventricular apex. A titanium can electrode (92‐cm2 surface area) was placed in the left pectoral area. The right ventricular lead was the anode for the first phase and the cathode for the second phase. The DFT was determined by a “down‐up down‐up” protocol. Statistical analysis was performed with a Wilcoxon matched pair test. The median impedance at DFT for expiration and inspiration phases were 37.8 ±3.1 Ω and 39.3 ± 3.6 Ω, respectively (P = 0.02). The stored energy at DFT for expiration and inspiration phases were 5.7 ± 1.9 J and 6.0 ± 1.0 J, respectively (P = 0.594). Shocks delivered at end‐inspiration exhibited a statistically significant increase in electrode impedance in a “hot can” electrode system. The finding that DFT energy was not significantly different at both respiration phases indicates that respiration phase does not significantly affect defibrillation energy requirements.
Inappropriate Sensing of Atrial Stimuli in Patients with Third‐Generation Defibrillators and DDD Pacemakers
Authors: LAMPERT RACHEL , McPHERSON CRAIG A. , LEWIS RICHARD J. , BATSFORD WILLIAM P. , ROSENFELD LYNDA E.
Published: July 2006

Although the problem of ICD sensing of paced ventricular stimuli has been resolved by incorporation of VVI pacing into current ICDs, many patients require separate DDD pacemakers. We report a problematic PM‐ICD interaction: the inability to prevent sensing of paced atrial stimuli (atrial sensing) leading to double‐counting in DDD‐PM‐requiring patients with transvenous (TV) ICDs with aggressive autogain sensing (CPI Ventak® PRxII or III). Four of eight patients receiving both transvenous DDD PMs and ICDs (CPI Endotak® lead, at the RV apex), had atrial sensing, leading to double counting, despite intraoperative testing of multiple atrial locations with an active fixation lead. Five patients had a PRxlI/III ICD, four with atrial sensing (80%), and three a PRx without atrial sensing. Patients with atrial sensing were not distinguished by any clinical or device related variable. In patients with atrial sensing (all with heart block), the PM was programmed to VDD mode. No patient has received inappropriate therapy or failed to sense VP in follow‐up. In many patients with TV ICDs who require DDD pacing, no atrial position can be found without ICD sensing of atrial stimuli. While in patients with heart block this problem can be circumvented by programming to the VDD mode, in patients with sinus incompetence it may only be resolved by the combination ICD‐DDD PM, currently in development.
A Fractally Coated, 1.3 mm2 High Impedance Pacing Electrode
Authors: FRÖHLIG GERD , BOLZ ARMIN , STRÖBEL JÖRG , RUTZ MARTIN , LAWALL PETER , SCHWERDT HOLGER , SCHALDACH MAX , SCHIEFFER HERMANN
Published: July 2006

Minimizing the geometric surface area of pacing electrodes increases impedance and reduces the current drain during stimulation, provided that voltage (pulse‐width) thresholds remain unchanged. This may be feasible by coating the electrode surface to increase the capacity of the electrode tissue interface and to diminish polarization. Ten unipolar, tined leads with a surface area of 1.3 mm2 and a “fractal” coating of Iridium (Biotronik SD‐V137) were implanted in the ventricle, and electrogram amplitude (unfiltered), slew‐rate, pacing threshold (0.5 ms), and impedance (2.5 V; 0.5 ms) were measured by the 5311 PSA (Medtronic). On days 0, 2, 5, 10, 28, 90, 180, 360 postimplant, sensing threshold (up to 7.0 mV, measuring range 1–14 mV on day 360 only) and the strength duration curve (0.5–4.0 V; 0.03–1.5 ms; steps: 0.5 V; 0.01 ms, respectively) were determined, the minimum charge delivered per pulse (charge threshold), and the impedance were taken from pacemaker telemetry (Intermedics 294–03). Data were compared with those of an earlier series of 20 unipolar, tined TIR‐leads (Biotronik) with a surface area of 10 mm2 and a “fractal” coating of titanium nitride. With the model SD‐V137 versus TIR, intraoperative electrogram amplitudes were 15.1 ± 6.1 versus 14.4 ± 3.9 mV(NS), slew rates 3.45 ± 1.57 versus 1.94 ± 1.06 V/s (P < 0. 05), pacing thresholds 0.16 ± 0.05 versus 0.52 ± 0.15 V (P < 0.01) and impedance measurements 1,136 ±175 versus 441 ± 73 Ω (P < 0.0001), respectively. During follow‐up, sensing thresholds were the same with both leads. Differences in pulse width thresholds lost its significance on day 28 but resumed on day 360 (SD‐V137: 0.08 ± 0.04 ms; TIR: 0.16 ± 0.06 ms at 2.5 V; P < 0.01). With an electrode surface of 1.3 mm2, charge per pulse and impedance consistently differed from control, beingO.15 ± 0.15 versus 0. 66 ± 0. 20 μC (P < 0.001) and 1,344 ± 376 versus 538 ± 79 Ω, respectively, one year after implantation (P < 0.0001). In summary, “fractally” coated small surface electrodes do not compromise sensing; by more than doubling impedance against controls they offer pacing thresholds (mainly in terms of charge) that are significantly lower than with the reference electrode.
Postshock Recovery Interval of Relatively Refractory Myocardium as a Possible Explanation for Disparate Defibrillation Efficacy Between Monophasic and Biphasic Waveforms
Authors: MURAKAWA YUJI , YAMASHITA TAKESHI , SEZAKI KAZUNORI , KANESE YUKIHIRO , OMATA MASAO
Published: July 2006

We investigated the electrophysiological background for the waveform related variability of defibrillation efficacy. In 22 open‐chest dogs, a localized potential gradient was created using an 8‐V or 16‐V field stimulus across a pair of plate electrodes separated by 5 mm. The postshock recovery interval of the nonde‐polarized myocardium adjacent to the excited area was estimated by the residual refractory period after an appropriately timed field stimulus. The postshock recovery interval and the defibriliation threshold were compared among six different waveforms but with the same total duration of 12 ms (n = 11) or 16 ms (n = 11). Six defibriliation thresholds in individual hearts showed a significant inverse correlation with postshock recovery intervals in most dogs (8/11 tested with a total pulse duration of 12 ms (8 V stimulus: r = ‐0.80 ± 0.20 [n = 11]). In contrast, waveforms with a total duration of 16 ms failed to reveal this distinct relationship. We conclude that the waveform related variability of defibrillation efficacy is associated with the refractoriness of relatively refractory myocardium when the total pulse duration is within a certain range. However, the mechanisms responsible for waveform performance may vary as the total pulse duration changes.
Electroanatomical Mapping of the Heart: Basic Concepts and Implications for the Treatment of Cardiac Arrhythmias
Authors: GEPSTEIN LIOR , EVANS STEVEN J.
Published: July 2006

The CARTO electroanatomical mapping system represents a paradigm shift in the ability to map the three‐dimensional anatomy of the heart and determine the cardiac electrical activity at any given mapped point. The system associates anatomical structure and electrophysiological data and displays the combined information in an easily readable, visual fashion. The system consists of a roving mapping catheter with small magnetic sensors in the tip, a fixed sensor that acts as a reference point, a low magnetic field generating pad, and a data acquisition and display system. When the roving catheter is moved in three‐dimensional space, its location in relation to the fixed sensor is monitored by the system, with a resolution of < 1 mm. By gating the acquisition of points in space to the cardiac electrical activity, points that represent both location and electrical activity at that location can be acquired and displayed on a computer screen. After acquiring a number of points, a three‐dimensional representation is constructed, and may be displayed from any viewing projection. Clinical applications of the system include defining the mechanisms of arrhythmias, designing ablation strategies, guiding ablations, and improving the safety of mapping and ablation procedures by allowing localization of critical cardiac structures such as the atrioventricular node and His bundle. The system holds the potential to both further our understanding of arrhythmias and increase the safety, efficacy, and efficiency of catheter ablation.
Use of a Three‐Dimensional, Nonfluoroscopic Mapping System for Catheter Ablation of Typical Atrial Flutter
Authors: NAKAGAWA HIROSHI , JACKMAN WARREN M.
Published: July 2006

Recent studies have shown that typical atrial flutter (AFL) results from right atrial reentry around the tricuspid annulus (TA), constrained between the TA and crista terminalis (CT) on the free‐wall and the TA and eustachian ridge (ER) on the septum. Creation of a complete line of conduction block across the subeustachian isthmus, between the TA and ER, elminates AFL. The accuracy of fluoroscopy in localizing the anatomical boundaries and previous radiofrequency application sites is limited. This article describes an approach for utilizing a new three‐dimensional nonfluoroscopic electroanatomical mapping system (CARTO) to examine the global right atrial activation pattern in patients during AFL, localize the anatomical boundaries, and create a complete line of conduction block by ablation across the subeustachian isthmus. During AFL, the locations of CT and ER are identified by double atrial potentials recorded along the intercaval region and between the inferior vena cava and coronary sinus ostium, respectively. Radiofrequency ablation across the subeustachian isthmus is performed during coronary sinus pacing. Beginning at TA, the ablation electrode is moved toward ER in 2–3 mm increments. Each movement is marked on the right atrial map to visualize the ablation line. In the event of residual conduction across the ablation line, defects in the ablation line are located by mapping along the previous ablation sites guided by CARTO system to locate the transition from the double atrial potentials (indicating block) to a single atrial potential (indicating conduction). Radiofrequency ablation to the site showing the single atrial potential along the ablation line produces complete conduction block across the subeustachian isthmus. In conclusion, the new electroanatomical mapping system allows precise 3‐D localization of the anatomical boundaries of the AFL reentrant circuit, and facilitates ablation by accurately locating defects in the ablation line.(PACE 1998; 21:1279–1286)
Entrapment of an Ablation Catheter in the Cardiac Venous System: A Case Report
Authors: SOPHER S. MARK , GRACE ANDREW A. , HEALD SPENCER C. , ROWLAND EDWARD
Published: July 2006

Cannulation of the coronary sinus is a common procedure with infrequent complications. We report an unusual case of a steerable “dumb‐bell” catheter passed through the ostium of the coronary sinus prior to an intended radiofrequency ablation procedure becoming stuck and requiring general anesthesia for extraction. We caution against the use of such catheters with a “waist” for the cannulation of the coronary sinus.
Alternative Locations for Internal Defibrillator Electrodes
Authors: VLAY STEPHEN C. , BILEINGER THOMAS V. , LEVY MICHAEL , CHITKARA VINAY
Published: July 2006

Successful defibrillation is described in two patients in whom the defibrillating electrode was positioned in the coronary sinus and right ventricular outflow tract as alternative sites. Internal cardiac defibrillation has been successful with single or multiple endocardial electrodes, epicardial patch electrodes, and subcutaneous surface electrodes (patch, array) in varying combinations and recently with an active can electrode. While the traditional location of the endocardial electrode has been the right ventricular apex, we describe two patients in whom defibrillation was successful in alternate locations, the coronary sinus and the right ventricular outflow tract.
Left Ventricular Malposition of a Transvenous Cardioverter Defibrillator Lead: A 3‐Year Follow‐Up
Authors: KUSNIEC JAIRO , MAZUR ALEXANDER , HIRSCH RAFAEL , STRASBERG BORIS
Published: July 2006

A case of left ventricular malposition of a transvenous implantable cardioverter defibrillator lead through an atrial septal defect is presented. The patient has been continually anticoagulated with warfarin. A 3‐year follow‐up has thus far been uneventful.
Successful Slow Pathway Ablation in a Patient with Atrioventricular Nodal Reentrant Tachycardia Having a Proximal Common Pathway
Authors: CHINUSHI MASAOMI , AIZAWA YOSHIFUSA , OGAWA YUSUKE , FUJITA SATOSHI , KUSANO YORIKO , MIYAJIMA SEIICHI , SHIBATA AKIRA
Published: July 2006

Radiofrequency catheter ablation was attempted in a patient with atrioventricular nodal reentrant tachycardia (AVNRT). AVNRT was easily inducible but an intermittent loss of the atrial activation was observed during AVNRT suggesting the presence of a proximal common pathway. During sinus rhythm, a relatively delayed activation that was compatible with a slow potential, was recorded anterior to the ostium of coronary sinus, and radiofrequency catheter ablation application (20 watts) to the site induced junction tachycardia. After an additional radiofrequency catheter ablation application to close the site, AVNRT became noninducible without deterioration of atrioventricular conduction through a fast pathway. This is the first case in which radiofrequency catheter ablation application to the slow potential recording site has been successful, even in AVNRT having a proximal common pathway.
Aborted Implantable Cardioverter‐Defibrillator Shock During Facial Electrosurgery
Authors: CASAVANT DAVID , HAFFAJEE CHARLES , STEVENS STEPHANIE , PACETTI PATRICIA
Published: July 2006

A patient with a fourth‐generation transvenous implantable cardioverter‐defibrillator system nearly received an inappropriate defibrillation discharge while undergoing electrofulguration of keratotic facial skin lesions. The incident was confirmed by analyses of the implantable cardioverter‐defibrillator's time/date stamped event log and stored electrogram record. Therapy was withheld by the noncommitted implantable cardioverter‐defibrillator as the pulsed electrocautery was not continued beyond the charging period.
Coronary Artery Dissection Complicating Radiofrequency Catheter Ablation via the Retrograde Approach
Authors: JANEIRA LOUIS F.
Published: July 2006

A case of acute coronary dissection complicating a left‐sided catheter ablation procedure via the retrograde approach.