bluuebunny/crossref_metadata_2025 huggingface dataset:
Dispersion of Ventricular Repolarization in the Voltage Domain
Authors: BEHRENS STEFFEN , LI CUILAN , KNOLLMANN BJÖRN C. , FRANZ MICHAEL R.
Published: July 2006

Dispersion of ventricular repolarization, assessed as QT dispersion in the ECG or by multiple monophasic action potential (MAP) recordings, is defined as the difference between the earliest and latest repolarization. It is thus measured in the time domain. However, myocardial refractoriness is primarily a function of the membrane potential during phase 3 repolarization. The purpose of this study, therefore, was to measure dispersion of ventricular repolarization in the voltage domain and to study its relation to VF inducibility. To further validate this concept, the effects of chronic amiodarone treatment on the voltage dispersion were assessed. MAPs were recorded simultaneously at 10 epicardial and endocardial sites in isolated rabbit hearts, both under baseline conditions (n = 8) and after chronic amiodarone treatment (n = 8). Repolarization dispersion in the voltage domain was calculated as the difference between the highest and lowest repolarization level of all 10 MAPs at 10‐ms steps, starting from the MAP plateau level to complete repolarization. Plotting these voltage differences along the time axis resulted in a dispersion curve, which rose during early repolarization, reached a peak during phase 3 repolarization, and thereafter declined toward zero. There was a close correlation between VF vulnerability in response to electrical field stimuli and the time during which voltage dispersion was maximal (r = 0.828, P < 0.0001). Amiodarone caused a right‐ward shift of both the dispersion curve (P = 0.007) and VF vulnerability (P = 0.025), but did not change the magnitude nor the shape of the voltage dispersion curve and its relation to VF vulnerability. Repolarization dispersion in the voltage domain describes an alternate approach for evaluating the heterogeneity of ventricular repolarization and may help to characterize arrhythmia susceptibility under experimental conditions.
Adenosine Sensitive Left Ventricular Tachycardia
Authors: DIKER ERDEM , TEZCAN KEMAL , ÖZDEMIR MURAT , GÖKSEL SIBER
Published: July 2006

Presented here is a 39‐year‐old male patient with no structural heart disease but a ventricular tachycardia with right bundle branch block morphology and right axis deviation, which is responsive to adenosine. The ventricular tachycardia was initiated by ventricular pacing, shown to originate from the mid‐anterior free wall region of the left ventricle and terminated by adenosine. Radiofrequency current application at a site where presumed P potentials were recorded eliminated the tachycardia, a finding that suggests that the origin of the tachycardia may be closely related to the anterior fascicle.
CGMP Levels Following ANF Challenge are Markers of Subsequent Successful Reversion of Lone Atrial Fibrillation to Sinus Rhythm
Authors: MESISKLI THEONI , FLEVARI PANAGIOTA G. , LIVANIS EFTHIMIOS G. , BOFILIS ELIAS , THEODORAKIS GEORGE N. , KREMASTINOS DIMITRIOS TH.
Published: July 2006

The aim of the present study was to assess whether cGMP release to ANP stimulation can be a biochemical marker of subsequent successful electrical cardioversion of lone atrial fibrillation to sinus rhythm. For this purpose, we studied 13 patients with chronic, lone atrial fibrillation of less than one year's duration who presented to our laboratory for electrical therapy of their arrhythmia. Prior to electrical cardioversion, peripheral venous cGMP levels were assessed at baseline and following an tntravenous challenge of 50 Ug human ANP. Venous blood samples for cGMP assessment were taken a) at baseline, b) 5 and 10 mins after the end of ANP infusion. ANOVA of repeated measures was used for statistical analysis. Eight of the study patients were successfully cardioverted to sinus rhythm, while the remaining 5 were not. Although no difference was noted between the two groups regarding the mean time of arrhythmia duration as well as left atrial and ventricular dimensions, ANP stimulation provoked significantly greater cGMP release in patients whose arrhythmia reverted to sinus rhythm, when compared with that of patients whose arrhythmia persisted (p<0.001). Therefore, cGMP levels following ANP challenge might discriminate between patients with chronic AF who are going to be successfully cardioverted and those who are not. These findings imply that the underlying atrial disease might be different in extent/nature between patients with lone AF responsive to cardioversion and those with resistant arrhythmia.
Prospective Evaluation Of The Length Of The Lower Common Pathway In The Differential Diagnoss Of Various Forms Of AV Nodal Reentrant Tachycardia
Authors: HEIDBÜCHEL HEIN , ECTOR HUGO , VAN DE WERF FRANS
Published: July 2006

The conduction time over the lower common pathway (LCP) in AVNRT can be assessed by subtracting the H A‐interval during tachycardia (HAt) from that during ventricular pacing at exactly the same cycle length (HAp) (ΔHA = HAp ‐ HAt). tt has been suggested that H‐A measurements may help in the differentiation of Slow/Fast from Slow/Slow AVNRT. This study evaluated prospectively in 61 consecutive patients with AVNRT (43 ± 15 y; 46 women, all with antegrade conduction during AVNRT over the slaw pathway) how often a reliable measurement of the length of the LCP could be made, and in how far the results were concordant with mapping criteria for the differentiation of Slow/Fast from Slow/Slow A VNRT. A new para‐Hisian pacing technique (using only the His bundle catheter) was applied in all patients. Comparison of HAt and HAp was possible in 44 of the 61 patients (72%). In these 44 patients, HAp was longer than HAt in 12 patients, indicating the presence of a LCP. All patients with ΔHA ≥ 15 ms had earliest retrograde atrial activation in the posterior septum (Slow/Slow AVNRT, n = 6) or simultaneously in the anterior and posterior septum (n = 1). On the other hand, 31 of the 32 patients without evidence of a substantial LCP (ΔHA ≤ 0) had typical Slow/Fast AVNRT. Moreover, although it appears logical for Slow/Fast A VNRT to have a shorter HAt than Slow'Slow A VNRT, an HAp of ≥ 70 ms was a better discriminator between the two forms of AVNRT than any HAt value. Therefore, ΔHA ≥ 15 ms (sens. ≥86%; spec. ≥97%) or HAp ≥ 70 ms (sens. = 100%; spec. ≥89%) were highly indicative for the Slow/Slow variant of AVNRT. Using a para‐Hisian pacing technique, H‐A measurements can be performed in 72% of A VNRT patients. They can be used as an important tool in the differentiation of Slow/Fast and Slow/Slow A VNRT.
Optimizing the Geometry of Implantable Leads for Recording the Monophasic Action Potential with Fractally Coated Electrodes
Authors: LANG VOLKER , MERKELY BÉLA , GELLÉR LÁSZLÓ , KISS ORSOLYA , STRÖBEL JÖRG P. , SCHALDACH MAX
Published: July 2006

This study investigates the influence of various lead geometry on intracardial signals like the monophasic action potential (MAP) to optimize the geometry of implantable MAP leads. The experimental results were compared with a field theoretical approach to the origin of MAP from the transmembrane potential (TAP). During the experiments several lead geometries (tip surface: 1.3 to 12 mm2; tip‐ring distance: 0.8 mm to 25 cm; ring surface: 1.8mm2 to 40 mm2) were investigated in endo‐ and epicardial positions in 12 dogs (17±9 kg). The electrodes were fixed passively (tines) or actively (screws). MAP was recorded during several interventions and correlated with MAP measured using an Ag‐AgCl MAP catheter. The experimental results showed that small tips provided high MAP amplitudes with less pressure. No difference was observed using active and passive fixations. A tip‐ring distance smaller than 5 mm with a ring surface smaller than the tip (<5 mm2) avoided artifacts in the repolarization course. For the theoretical approach the quasistatic, anisotropic bidomain model was calculated in smalt unity volumes Vi where the TAP φm was constant and represented by the current density J. Two solutions for electrode positions at and outside the heart were achieved. By superposition of each solution φei the summed potential at the electrode position was calculated. The theoretical findings show in good correlation with the experimental results that a larger distance than 10 mm leads to distortions in repolarization course by signals proportional to φout.
Permanent Left Ventricular Pacing With Transvenous Leads Inserted Into The Coronary Veins
Authors: DAUBERT J. CLAUDE , RITTER PHILIPPE , LE BRETON HERVÉ , GRAS DANIEL , LECLERCQ CHRISTOPHE , LAZARUS ARNAUD , MUGICA JACQUES , MABO PHILIPPE , CAZEAU SERGE
Published: July 2006

This paper describes a preliminary experiment ‐ conducted jointly by 2 centers ‐ of permanent left ventricular pacing using leads inserted by the transvenous route and through the coronary sinus into the cardiac veins of the left ventricle free wall. The aim was to obtain permanent biventricular pacing in a totally endocavitary configuration in pattents with severe LV dysfunction and drug‐refractory heart failure. Two types of leads were used: nonspecific unipolar leads at the beginning of the experiment, followed by leads specifically designed to be used in the coronary sinus in a second step. The electrode could be fitted in an adequate location in 35 of the 47 patients (75.4%), with a 1.15±0.7 V acute pactng threshold and 11.8±5.7 mV R wave amplitude. The success rate was significantly higher with the specific electrodes (81.8% vs 53,3%, p < 0.001). The pacing and sensing thresholds upon implantation were not influenced by the type of lead or by the localization of the cardiac vein that was catheterized (great cardiac vein, lateral vein, postero‐lateral or posterior vein, mid cardiac vein). In contrast, the pacing threshold was significantly lower (0.8 ± 0.2 vs L8 ± 0.8 V; p = 0.002) and the R wave amplitude tended to be greater (13.1 ± 4.5 mV vs 9.3 ± 6.5 mV; p = 0.07) when the tip electrode could be inserted distally into the vein, by comparison with a proximal site near the ostium. At the end of follow‐up (10.2 ± 8.7 months), 34 out of the 35 leads were still fully functional, with a chronic pacing threshold of 1.8 ± 0.7 V and a R wave amplitude of 10.7 ± 6 mV. To conclude, permanent LV pacing via the transvenous route is possible in most patients, with excellent safety and long‐term results.
Incidence of Atrial Fibrillation in Patients with Different Mode of Pacing. Long‐term Follow‐up
Authors: FOLINO ANTONIO FRANCO , BUJA GIANFRANCO , CORSO LORENZA DAL , NAVA ANDREA
Published: July 2006

We evaluated the incidence of atrial fibrillation in 189 patients (92males, 97females, mean age 75 ± 12yrs, range 41–100yrs) with pacemaker, during a mean follow‐up of 5.5yrs (range 1–24yrs). The indications for implant were: complete AV block (115pts), second degree Möbilz 2 AV block (51pts). bifascicular block (5pts). sick sinus syndrome (14pts), symptomatic bradycardia (4pts). The mode of stimulation considered were VVI (105pt), VVI rate responsive (21pts), single lead VDD (43pts), DDD (20pts). The occurrence of retrograde VA conduction in patients with VVI or VVI rate responsive pacing was also evaluated. Atrial fibrillation occurred in 40 pts (21%). The highest incidence was evidenced in patients with sick sinus syndrome (9pts, 64%), and in patients with VVI stimulation (28pts, 27%). On the contrary, the lowest incidence was found in single lead VDD stimulation (4pts, 9%). The patients with dual chamber pacing showed a relatively high incidence of the arrhythmia (5pts, 25%). Atrial fibrillation occurred in 9 out of 32 patients with retrograde VA conduction, and in 22 out of 94 patients without retrograde conduction (28% versus 23%, p=NS). In conclusion, it is confirmed that patients with sick sinus syndrome are at high risk for atrial fibrillation. Single lead VDD stimulation seems to be the better mode of pacing in preventing atrial fibrillation, while dual chamber pacing showed minor efficacy. The presence of retrograde VA conduction could not predict the occurrence of the arrhythmia.
Atrial Synchronous Ventricular Pacing with a Single Lead: Reliability of Atrial Sensing During Physical Activities, and Long‐term Stability of Atrial Sensing
Authors: FAERESTRAND SVEIN , OHM OLE‐JØRGEN
Published: July 2006

A VDD pacing system with bipolar single‐pass leads, were implanted in 36 consecutive patients (average age 72 ± 2years) with high degree atrioventricular block and normal sinus node function. At implant the atrial signal amplitude was 2.6 ± 0.2mV measured by a pacing system analyser (PSA), 1.8 ± 0.1mV measured peak‐to‐peak from the telemetered calibrated electrogram, and 1.3 ± 0.1mV measured from the sensing threshold. At one month follow‐up the peak‐to‐peak amplitudes (mV) of the telemetered atrial electrograms were not significantly different measured continuously during resting supine with quiet breathing (1.4 ± 0.1), sitting (1.6 ± 0.2). standing (1.5 ± 0.1), arm swinging (1.4 ± 0.2), hyperventilation (1.3 ± 0.1), Vaisalva manoeuvre (1.4 ± 0.1), and treadmill exercise (1.9 ± 0.6). The telemetered atrial electrogram amplitude and the atrial sensing threshold varied between 1.2 ± 0.09mV and 1.8 ± 0.1mV, and between 0.95 ± 0.07mV and 1.3 ± 0.01mV, respectively at 0.5, 1, 3, 6 and 12 months follow‐up, but the changes were statistically nonsignificant. The Event Summary showed sensing of 98% to 99% of the atrial events at the different follow‐up periods.
Factors Influencing Long Term Persistence of Sinus Rhythm After a First Electrical Cardioversion for Atrial Fibrillation
Authors: DUYTSCHAEVER MATTIAS , HAERYNCK FILOMEEN , TAVERNIER RENE , JORDAENS LUC
Published: July 2006

It is conventionally thought that electrical cardioversion in patients with atrial fibrillation (AF) of longstanding duration or with a large lefi atrial diameter, only seldom results in long term success. Recurrence is common, although antiarrhythmic drugs often effectively decrease the number and duration of recurrent AF episodes. We analysed clinical, functional and pharmacological variables which could possibly infiuence the long term outcome after a first electrical cardioversion for AF in a retrospective study on 85 patients. Univariate and multivariate analysis was used to identify factors predicting maintenance of sinus rhythm at 100 days, and absence of recurrence during the entire follow‐up. In univariate analysis, the only significant predictor for maintenance of sinus rhythm at 100 days was the duration of the preceding AF episode. Multivariate analysis with persistence of sinus rhythm at 100 days as endpoint confirmed this as a prognostic factor (p <0.03), but sotalol treatment also contributed to maintenance of sinus rhythm (p <0.05). When considering ihe entire observation period, class III antiarrhythmic drugs, i.e. sotalol ami amiodarone, were useful in preventing recurrence (p <0.01 and < 0.02). High age (above 75 years) was a predictor of recurrence. In conclusion, class III antiarrhythmic drugs, the duration of atrial fibrillation and high age were the most important determirumts of long term outcome, while echocardiographic parameters and the presence of heart disease played no role.
Feasibility and Safety of a Minimally Invasive Approach to Catheter Ablation for Atrioventricular Nodal Reentrant Tachycardia
Authors: HII JOHN T.Y. , WUTTKE RONALD D. , KALABURNIS MARTHA , VELISARRIS GEORGIA
Published: July 2006

This study assessed the feasibility and safety of a minimally invasive approach to catheter ablation in 72 consecutive patients with A V nodal reentrant tachycardia. A 3‐catheter approach was used in the first 19 patients. In the other 53 patients, a 2‐catheter approach was employed. Ablation was successful in all patients after a mean of 3 ± 3 RF applications. Procedure and fluoroscopy times were 62 ± 20 mins and 8 ± 5 mins respectively. Slow pathway was ablated in 43 patients (60%). Transient A V block occurred in 6 patients; there was no permanent AV block. These results suggest that it is feasible to perform ablation for AV nodal reentrant tachycardia safely and with high efficacy using a minimally invasive approach. This has the potential to lessen patient discomfort and to further shorten procedure and radiation exposure times.
Lesion Size in Relation to Ablation Site During Radiofrequency Ablation
Authors: PETERSEN HELEN HØGH , CHEN XU , PIETERSEN ADRIAN , SVENDSEN JESPER HASTRUP , HAUNSØ STIG
Published: July 2006

This study was designed to investigate the effect of the convective cooling of the tip of the ablation electrode during temperature controlled radiofrequency ablation. In vivo two different application sites in the left ventricle of anaesthetised pigs were ablated and in vitro ablation was performed during two different flow‐velocities in a tissue bath, while electrode contact pressure and position were unchanged. Target temperature was 80 °C. Obtained tip temperature, power consumption and lesion dimensions were measured. In vivo lesion volume, depth and width were found significantly larger for septal applications than apical applications (p<0.01) and more power was used (p<0.001). Obtained tip temperature was significantly lower in the septal applications (p<0.001). In vitro increased convective cooling by induction of flow yielded larger lesion volume, depth and width (p<0.01), and had higher power consumptions (p<0.01). Obtained tip temperature did not differ significantly. For the given chosen target temperature power consumption was positively related to lesion volume (r= 0.66 in vivo and 0.65 in vitro), whereas obtained tip temperature was not (r = ‐ 0.49 in vivo and ‐ 0.61 in vitro). We conclude that during temperature controlled radiofrequency ablation lesion size differs for septal and apical left ventricular applications. Differences in convective cooling might play an important role in this respect. This is supported by our in vitro experiments, where increased convective cooling by induction of a flow around the electrode tip increases lesion dimensions and power consumptions. Furthermore we conclude that for the given target temperature the power consumption is positively correlated with lesion volume (p<0.001), whereas the obtained tip temperature is not.
Does Radiofrequency Catheter Ablation Induce a Deterioration in Sympathetic Innervation? A Positron Emission Tomography Study
Authors: SCHMITT CLAUS , MEYER CHRISTIAN , KOSA ISTVAN , WEYERBROCK SONJA , SCHNEIDER MICHAEL , ZRENNER BERNHARD , PLEWAN ANDREAS , SCHÖMIG ALBERT , SCHWAIGER MARKUS
Published: July 2006

Radiofrequency catheter ablation (RFCA) is an effective treatment for the interruption of accessory bypass tracts in WPW syndrome or the modification of the Ay‐nodal conduction system in patients with A V‐nodal tachycardias. However RFCA may also damage cardiac innervation. The purpose of this pilot study was to assess possible changes in sympathetic innervation after RFCA as evaluated by the cathecholamine analog carbons‐11‐ hydoxyephedrine (HED) positron emission tomography (PET) which allows the visualisation of sympathetic nerve terminals. We investigated nine patients with supraventricular tachycardias before and two to six weeks after RFCA. Myocardial perfusion was depicted by n‐I3‐ammonia‐PET. In addition to visual analysis, HED retention was quantified in the myocardial quadrant distal to the location of intervention; these results were compared with values in remote areas. Before RFC A, myocardial perfusion showed homogenous distribution in 8 of 9 patients. One patient showed a perfusion defect in the posterior wall. HED retention matched perfusion distribution in all patients. After RF'CA there was no significant change observed either in ammonia or in HED distribution. Quantitative HED retention data showed no significant change before versus after RFC A. Thus, HED‐PET does not demonstrate any abnormalities of tracer uptake indicating integrity of sympathetic nerve terminals after radiofrequency ablation therapy.
Cardiac Arrest and Sudden Death in Competitive Athletes with Arrhythmogenic Right Ventricular Dysplasia
Authors: FURLANELLO F. , BERTOLDI A. , DALLAGO M. , FURLANELLO C. , FERNANDO F. , INAMA G. , PAPPONE C. , CHIERCHIA S.
Published: July 2006

Arrhythmogenic right ventricular dysplasia (ARVD) is a predisposing factor for sportrelated cardiac arrest (CA), sudden cardiac death (SD). and life‐threatening ventricular tachyarrhythmias (VT). The aim of this study was the assessment of athletes with ARVD, particularly the CA survivors. From 1974 to January 1996, 1642 competitive athletes (aver. 25.5 yr.), 136 of whom were top level athletes (TLA), were studied for important arrhythmic manifestations. All athletes underwent an individualised study protocol including a series of non invasive and invasive diagnostic techniques. One hundred and one athletes (90 males, 11 females, aver. 25.9 yr.) were diagnosed as being affected by ARVD on the basis of the WHO/ISFC criteria. The same percentage (about 6%) of ARVD is present in both the general arrhythmic athletes population and in the subgroup of TLA. Prevalence of ARVD among athletes with CA or SD is high (respectively 23% and 25%), confirming the observation that ARVD is one of the major causes of SD in Italian athletes. All CA were athletic activity related, indicating the potentiality of exercise as a cause of electrical destabilisation in subjects with ARVD. In athletes with documented ARVD intense sport activity has to be proscribed. In athletes at risk of CA or SD an aggressive treatment, ICD implantation and RF catheter ablation must be taken into consideration.
Advanced Atrioventricular Block in a 39‐Year‐Old Man with Acute Rheumatic Fever
Authors: BAROLD S. SERGE , SISCHY DAVID , PUNZI JOHN , KAPLAN EDWARD L. , CHESSIN LAWRENCE
Published: July 2006

This report describes the development of advanced (2:1 and 3:1) AV block in a 39‐year‐old man with acute rheumatic fever. AV block progressed from first‐degree to type I second‐degree and finally to advanced AV block. The latter lasted 5 days. AV block regressed in a stepwise fashion via sustained type I second‐degree AV block and eventually first‐degree AV block. The PR interval returned to normal several weeks after resolution of second‐degree AV block. In view of the resurgence of acute rheumatic fever, the diagnosis of acute rheumatic fever should now be considered in young adults or middle‐aged patients presenting with second‐degree or third‐degree AV block of undetermined etiology.
Uncommon Atrial Flutter: Characteristics, Mechanisms, and Results of Ablative Therapy
Authors: GOMES J. ANTHONY , SANTONI‐RUGIU FRANCESCO , MEHTA DAVENDRA , LANCAN NOELLE M. , MARX STEVEN O. , NAYAK HEMAL
Published: July 2006

Thirty‐seven patients with atrial flutter were studied with catheter mapping and radiofrequency ablation. Uncommon atrial flutter occurred in 20 out of 37 (54%) patients. Atrial endocardial mapping showed two types of uncommon atrial flutter. In 15 patients (group I) it was characterized by a single clockwise circuit whereas in 5 patients (Group II) it was characterized by the presence of more than one circuit and/or localized atrial fibrillation. RFA ablation was acutely successful in 14 out of 15 patients (93%) in Group I and in 2 oat of 5 (40%) patients in Group II. On long‐term follow‐up a significantly larger number of patients in Group I versus Group II (86% vs 20%) remained free of atrial flutter recurrence. We conclude that uncommon atrial flutter is a heterogeneous entity involving one or more reentrant circuits. Uncommon atrial flutter with multiple circuits may not be suitable for RFA.
Microwave Linear Ablation of the Isthmus Between the Inferior Vena Cava and Tricuspid Annulus
Authors: LIEM L. BING , MEAD R. HARDWIN
Published: July 2006

The purpose of this study is to assess the potential utility and practicality of microwave (MW) ablation in the creation of linear lesion for the treatment of atrial flutter. In the search for a more versatile form of energy for ablation of complex arrhythmias, MW, with its more direct form of heating, has been considered a potential alternative to radiofrequency. MW ablation is expected to offer an advantage in creating deeper or more uniform linear lesions but data on its usefulness remain lacking. Microwave ablation was applied to the inferior vena cava and tricuspid annulus isthmus in eight canines weighing 67.2 ± 4.8 lbs. We applied stationary ablations across the isthmus using 60–75 W power of 2,450–MHz MW energy delivered through a deflectable catheter with a 12‐or 18‐mm antenna, achieving 70.1±± 9.0±C antenna's temperature. Ablations were made between the coronary sinus os and the low lateral right atrium. Bi‐directional block at the isthmus was accomplished in seven canines with an average of 2.7 ± 1.3 ablations while in one canine, only unidirectional block was achieved after five ablations. Gross pathological examination identified 16 transmural ovaloid and linear lesions measuring 9,4 ± 3.4 mm long, 4.9 ± 2.0 mm wide, and 2.1 ± 0.6 mm deep. In one canine the lesion extended to the surface of the tricuspid valve leaflet and in two other to the opposing anterior right ventricular wall. There were no coronary vascular or other structural damage. Histopathological examination showed hemolyzed blood on the surface, subendocardial hemorrhage and necrosis, and degeneration and fragmentation of the atrial myocardium. We concluded that single application ablation could achieve complete isthmus block using MW energy delivered through appropriately sized antenna. Such ablation may be useful for producing linear lesions for the treatment of atrial flutter.
The Influence of Sensor Orientation on Activity‐Based Rate Responsive Pacing
Authors: THERES HEINZ , PHILIPPON FRANCOIS , MELZER CRISTOPH , COMBS WILLIAM , PREST‐BERG KEVIN ,   SENSOR ORIENTATION STUDY GROUP
Published: July 2006

Piezoelectric activity‐based rate responsive pacemakers are commonly implanted with the sensor facing inward. This study was conducted to assess the safe and effective rate response of an activity‐based rate responsive pacemaker implanted with the sensor facing outward. A comparison were made to a previously studied patient group with sensor facing inward. Patient and pacemaker data was collected at pre‐discharge and 2‐month follow‐up. Two‐minute hall walks in conjunction with programmer‐assisted rate response assessment were utilized to standardize initial rate response parameter settings for both patient groups. At 2‐month follow‐up, sensor rate response to a stage 3 limited CAEP protocol was recorded. Adequate sensor rate response was achieved for both patient groups. No difference was noted in reported patient complications for both groups. A statistically significant difference in programmed rate response curve setting and activity threshold for the two groups was noted at 2‐month follow‐up. Adequate sensor rate response was achieved for a patient population implanted with an activity‐based rate responsive pacemaker with sensor facing outward. In this orientation, one higher rate response curve setting and an activity threshold one value more sensitive were required on average when compared to the normal sensor‐orientation group.
Metastatic Tumor Thrombus Attached to a Pacemaker Electrode
Authors: TADA HIROSHI , ASAZUMA KENYA , NAIKI HIRONOBU , NAKAI TSUGUHIKO , NAKAKUKI KAZUYA
Published: July 2006

We present a patient with a large tumor embolus attached to a pacemaker electrode leading to multiple pulmonary emboli. At postmortem examination, this thrombus was composed of clusters of well‐differentiated squamous cell carcinoma intermingled with fibrin. Tumor involvement was not evident in the myocardium, endocardium, or epicardium. The primary tumor was discovered in the lower intrathoracic esophagus. Tumor microamboli from the esophageal primary lesions may have accumulated around the pacemaker electrode due to turbulent flow in this region, producing a large and friable tumor embolus.
Right Ventricular Outflow Tract Tachycardia as a Result of Blunt Chest Trauma
Authors: MERA FERNANDO , WALTER PAUL F. , LANGBERG JONATHAN J.
Published: July 2006

Two patients presented with monomorphic ventricular tachycardia after blunt chest trauma. In both cases, the arrhythmia had a left bundle branch block, inferior axis morphology comparable to that seen with idiopathic ventricular tachycardia originating from the right ventricular outflow tract (RVOT). In one patient, the arrhythmia persisted and required catheter ablation. A history of cardiac trauma should be considered in patients presenting with RVOT tachycardia.
Peak Endocardial Acceleration‐Based Clinical Testing of the “BEST” DDDR Pacemaker
Authors: LANGENFELD HEINER , KREIN AXEL , KIRSTEIN MICHAEL , BINNER LUDWIG ,   EUROPEAN PEA CLINICAL INVESTIGATION GROUP
Published: July 2006

The peak endocardial acceleration (PEA, unit g) shows a near correlation with myocardial contractility during the isometric systolic contraction of the heart (dP/dtmax), with sympathetic activity and, thus, with physiological heart rate modulation. The (Biomechanical Endocardial Sorin Transducer (BEST) sensor is incorporated in the tip of a pacing lead and measures PEA directly near the myocardium. In an international study, the lead was implanted with the dual chamber pacemaker Living‐1 (Sorin) in 105 patients. The behavior of the PEA signal was tested under conditions of physical and mental stress and during daily life activities by 24‐hour recordings of PEA (PEA Holter) at 1 to 2 months and approximately 1 year after implantation. Implantation of the BEST lead was performed without complications in all patients. The sensor functioned properly in the short‐ and long‐term in 98% of patients. Although PEA values differed from patient to patient, the values closely reflected the variations in sympathetic activity due to physical and mental stress in each patient. During exercise and during daily life activities a close correlation between PEA and heart rate was observed among patients with normal sinus rhythm. Peak endocardial acceleration allows a nearly physiological control of the pacing rate.
How Reliable is Atrial Sensing in Single‐Lead VDD Pacing: Comparison of Three Systems
Authors: NOWAK BERND , MIDDELDORF THOMAS , VOIGTLÄNDER THOMAS , ROSOCHA STEFAN , LIEBRICH ANDREAS , ZELLERHOFF CHRISTIAN , PRZIBILLE OLIVER , HIMMRICH EWALD , MEYER JÜRGEN
Published: July 2006

This study evaluated the reliability of atrial sensing, expressed as AV synchronous stimulation, in three VDD systems with the atrial sensitivity (AS) programmed to a conventional value with a 2:1 safety margin compared to most‐sensitive values. We studied 34 sex‐ and age‐matched patients with 3 VDD systems: 14 with Unity 292–07, 10 with Saphir 600, and 10 with Thera VDD (5 model 8948 and 5 model 8968i). Two 24‐hour Hollers were performed on consecutive days. The AS was programmed in a randomized order to its most‐sensitive value or to a 2:1 safety margin. All other parameters were programmed identically. The patients underwent a myopotential oversensing test and a daily life activity protocol. A beat‐to‐beat analysis of the Holters was performed to determine AV synchrony. For the entire group AV synchrony with conventional AS was 98.63%± 2.57%, compared to 99.80%± 0.43% with most‐sensitive values (p = 0.002). There was no difference between the three systems with conventional AS. With the most‐sensitive AS, AV synchrony was: Unity 99.99%± 0.03%, Saphir 99.42%± 0.60% (P = 0.002), Thera 99.81 %± 0.35% (ns). In the Saphir system with an atrial blanking period of 150 ms, ventricular far‐field sensing could be demonstrated in 5 of 10 patients. This reduced the percentage of AV synchrony due to an unwanted mode‐switch to a nontracking mode. Myopotential oversensing was not detected in any patient. Conclusion: The VDD systems tested under identical conditions showed reliable P wave sensing at the most‐sensitive atrial sensing setting without myopotential oversensing. Ventricular far‐field sensing reduced AV synchrony and must be avoided by appropriate refractory periods.
Long‐term Survival of VDD Pacing
Authors: CHAMBERLAIN‐WEBBER RAFE , BARNES EDWARD , PAPOUCHADO MARK , CRICK JONATHAN PITTS
Published: July 2006

All patients with VDD systems implanted at a tertiary pacing center were identified from a computer database and data collected on pacing indications, follow‐up duration, rate response, reasons for programming changes, and implant P wave amplitudes. Results: 366 implants were identified for which complete data were available for 335 leads implanted in 316 patients. The mean follow‐up period was 24.1 months, and age at implant was 73.5 ± 11.8 years. During follow‐up, 19 patients died (6%) and 62 (19.6%) were followed elsewhere. Indications for pacing were complete heart block, 56.6%; intermittent AV block, 21.8%; postablation complete heart block, 5.4%; 2:1 AV block, 13%; and others, 3.2%. Two groups: no mode change (NMC, n = 280) and mode change (MC, n = 36) were identified. Reasons for reprogramming in the MC group were as follows: atrial sensing, 11; AF/atrial flutter, 18; chronotropic incompetence, 3; and others 4. Significantly more MC patients had rate response programmed ON (44.4% vs 22.1%, P < 0.05). No significant differences between the two groups were found in other variables, including male gender (55.5% vs 54.6%), length of follow‐up (27.1 ± 17.8 vs 23.8 ± 20.6 months), age at last follow‐up (72 ± 12.3 vs 75.9 ± 11.9years), and P wave amplitude (1.7 ± 0.9 vs 1.8 ± 0.9mV). Conclusion: Reprogramming of VDD systems is infrequent. When necessary, it is usually prompted by atrial arrhythmias or failure of atrial sensing. When adequate atrial chronotropy has been verified, VDD is an acceptable alternative to DDD pacing and survives well over the long term.
Multisite Pacing as a Supplemental Treatment of Congestive Heart Failure: Preliminary Results of the Medtronic Inc. InSync Study
Authors: GRAS DANIEL , MABO PHILIPPE , TANG TONY , LUTTIKUIS OUDE , CHATOOR ROGER , PEDERSEN ANDERS‐KIRSTEN , TSCHELIESSNIGG HARL‐HEINZ , DEHARO JEAN‐CLAUDE , PUGLISI ANDRÉAS , SILVESTRE JORGE , KIMBER S. , ROSS H. , RAVAZZI ANTONIO , PAUL VINCE , SKEHAN DOUGLAS
Published: July 2006

This report describes the initial results of the “InSync” study, a European and Canadian multicenter trial that examines the safety and efficacy of a multisite pacemaker (Medtronic InSync) and of left ventricular pacing leads (Medtronic 2187 and 2188) implanted via a cardiac vein as a supplemental treatment of refractory congestive heart failure. Over a 10‐month period, the system was implanted successfully in 68 of the 81 (84%) patients who had been enrolled in the study. The 68 patients were, on average, 66 ± 10 years old, had a mean left ventricular ejection fraction (LVEF) = 21 %± 9%, and 63% were in NYHA functional Class III and 37% were in Class IV. No system implant related complication occurred. During follow‐up, 7 of 10 patients who exited the study had died, 4 suddenly. There was a clinical benefit among surviving patients, which was corroborated by a significant improvement in NYHA functional class and in the Minnesota Living with Heart Failure Quality of Life Questionnaire Score (MLS) and by a longer distance covered during a 6‐minute walk test. This clinical improvement was associated with a significant narrowing of the paced QRS complex during biventricular pacing, a significant decrease in the interventricular mechanical delay, and a trend towards an increase in the duration of ventricular filling. These encouraging preliminary results confirm the feasibility and reliability of this new multisite pacing system in the management of dilated cardiomyopathy and support the continuation of further evaluations of this complementary treatment of refractory congestive heart failure.
Optimization of Ventricular Function by Improving the Activation Sequence During Ventricular Pacing
Authors: PRINZEN FRITS W. , VAN OOSTERHOUT MATTHIJS P.M. , VANAGT WARD Y.R. , STORM CORSTIAAN , RENEMAN ROBERT S.
Published: July 2006

Abnormal electrical activation occurring during ventricular pacing reduces left ventricular (LV) pump function. Two strategies were compared to optimize LV function using ventricular pacing, minimal asynchrony and optimal sequence of electrical activation. ECG and hemodynamics aortic flowpmbe, thermodilution cardiac output, LV pressure and its maximal rates of rise (LVdP/dtpos) and fall (LVdP/dtneg) were measured in anesthetized open‐chest dogs (n = 7) with healthy hearts. The QRS duration (a measure of asynchrony of activation) was 47 ± 5 ms during sinus rhythm and increased to 110 ± 12 ms during DDD pacing at the right ventricular (RV) apex with a short AV interval. During pacing at the LV apex and LV base, the QRS duration was 8%± 7% and 15%± 7% (P < 0.05) longer than during RV apex pacing, respectively. Stroke volumes, LVdP/dtpos and LVdP/dtneg, however, were higher during LV apex(15%± 16%, 10%± 12% [P<0.05], and 15%± 10%, respectively) and LV base pacing (11%± 12% [P<0.05], 3%± 12%, and 3%± 11%, respectively) than during RV apex pacing. Systolic LV pressure was not influenced significantly by the site of pacing. Biventricular pacing (RV apex together with one or two LV sites) decreased the QRS duration by approximately 20% as compared with RV apex pacing, however, it did not improve stroke volumes, LVdP/dtpos and LVdP/dtneg beyond those during pacing at the LV apex alone. In conclusion, the sequence of electrical activation is a stronger determinant of ventricular function than the synchrony of activation. For optimal LV function the selection of an optimal single pacing site, like the LV apex, is more important than pacing from multiple sites.
Bipolar Active Fixation Atrial Leads: Comparison of Two New Lead Models
Authors: KINDERMANN MICHAEL , SCHWAAB BERNHARD , FRÖHLIG GERD , LAWALL PETER , SCHIEFFER HERMANN
Published: July 2006

The purpose of the study was to examine the pacing and sensing characteristics of two bipolar active fixation atrial leads with a coaxial and a coradial conductor design, respectively. One group of ten patients received the ELA model S44F (4 mm 2 vitreous carbon tip, coaxial multifilar coils, silicons). Nine other patients received the Intermedics ThinLine EZ 438–10 (8 mm2 iridium oxide‐coated titanium tip, parallel‐wound bifilar coil, polyurethane). Both lead models had electrically insulated corkscrews. Intraoperatively, pacing threshold (PT) at 0.50 ms, unfiltered atrial potential (AP), slew rate (SR) and pacing impedance (Z) at 2.5 V, 0.50 ms were measured using a Medtronic 5311 PSA. On the day of implant, and 2, 5, 10, 28, 90, 180, and 360 days after implant, minimum charge threshold (δQmin), atrial sensing threshold (Asen) and Z were measured via telemetry of the pacemaker (Intermedics 294–03 and 294–09). Z was significantly lower (P < 0.01) in the ThinLine EZ group at implant (419 Ω vs 576 Ω, mean values, 436–10 vs S44F) and at each follow‐up (317–126 Ω vs 492–613 Ω). Five of nine patients with the 438–10 lead had Z values < 300 Ω during follow‐up (minimum 234 Ω). There was no significant difference between the two leads with respect to PT (0.42 V vs 0.41 V), AP (3.75 mV vs 4.25 mV), SR (0.56 vs 1.06), ±Qmin (0.19–1.23 μC vs 0.18–1.35 μC) and Asen (3.4–4.5 mV vs 2.7–4.7 mV), respectively. Two patients developed pericardial effusions after implantation of a ThinLine EZ lead. One of them, who had a transient drop of blood pressure during implant, subsequently developed acute exsudative pericarditis. Therefore, both leads had acceptable sensing and pacing thresholds, but the 438–10 lead developed unusually low long‐term lead impedance values. The high incidence of perforations in our small group of 438–10 patients has not been observed, thus far, in other studies.
Clinical Experience with Passive‐Fixation Coradial Bipolar Endocardial Pacing Leads
Authors: BELOTT PETER H. , RIZO‐PATRÓN CARLOS , BROWNSTEIN SHELDON L. , ANTIMISIARIS MICHAEL , TYERS G. FRANK O. , RAMOS JOSÉ L. ,   TbinLine™ Clinical Investigators
Published: July 2006

Bipolar, transvenous, passive‐fixation leads (ThinLine(tm) Sulzer Intermedics Inc., Angleton, TX, USA) incorporating coradial individually coated conductor coils, and a redundant external 55D polyurethane insulation sheath were developed. The diameter of the new leads (< 5 FT) is in the range of available unipolar leads and is considerably smaller than conventional bipolar pacing leads. From January 9, 1994 to November 12, 1996, 1,536 model 432–04 (523 atrial) and 430–10 (1,013 ventricular) leads were implanted in 1,068 patients at 50 US and 5 Canadian centers to evaluate their safety and efficacy. The study included a general phase, with follow‐ups at 1, 3, 6, 12, 18, and 24 months; and a randomized intensive phase with collection of more data and additional 2‐ and 6‐week follow‐ups. Capture and sensing thresholds, lead impedance, and handling characteristics were evaluated. Clinical events were monitored and performance was compared to that of two commercially available conventional (coaxial) leads: Sulzer Intermedics models 432–03 (atrial) and 430–07 (ventricular). During a total of 17,530 device months, there were two lead failures, no lead related deaths, 32 explants, 37 complications, and no unexpected adverse device effects. Capture thresholds were lower than those for coaxial controls with identical electrodes, sensing was comparable, lead impedances were within clinically acceptable ranges, and investigators found overall handling characteristics good to excellent. ThinLine coradial bipolar leads are safe and effective for cardiac pacing and sensing.
Blind Extrathoracic Subclavian Venipuncture for Pacemaker Implant: A 3‐Year Experience in 250 Patients
Authors: GARDINI ARMANDO , BENEDINI GIUSEPPE
Published: July 2006

We report our 3‐year experience using a modification of the percutaneous technique for extrathoracic subclavian Venipuncture proposed by Magney and colleagues for permanent pacing lead placement. Before surgery bony landmarks were marked on the skin according to Maguey's description to identify the needle entry point and the target point corresponding to the ideal location of the extrathoracic portion of the subclavian vein. Then the venipuncture was accomplished by inserting the needle through a standard infraclavicular pacemaker pocket. Two hundred fifty patients undergoing primary pacemaker implant (231 patients) or reimplant or change of mode of pacing (19 patients) were included in the study. The technique was successful in 245 (98%) cases. Inadvertent puncture of the subclavian artery occurred in 5 (2%) patients but in no case did it jeopardize the success of the implant procedure. No major complications were observed. Seven (2.9%) patients experienced early complications unrelated to the venous approach: 2 subclavian vein thrombosis, 5 lead dislodgment in 4 patients, and 1 pocket hematoma. During a mean follow‐up of 15.2 months (range 4–40) no lead or patient related complications occurred. In the present study the blind approach to the extrathoracic portion of the subclavian vein proved to be safe and effective for pacing lead insertion. Further observations are required to establish whether this method extends the lead survival.
Spontaneous Versus Extraction Related Injuries Associated With Accufix J‐wire Atrial Pacemaker Lead: Tracking Changes in Patient Management
Authors: KAWANISHI DAVID T. , BRINKER JEFFREY A. , REEVES RUSSELL , KAY G. NEAL , GROSS JAY , PIOGER GUY , PETITOT JEAN‐CLAUDE , ESLER ANNE , GRUNKEMEIER GARY
Published: July 2006

To make recommendations for management of potentially fatal failure of the Accufix series of atrial J‐wire permanent pacemaker leads, we closely monitored the number of injuries and fatalities resulting either from spontaneous fracture of the J‐wire or from attempts to extract the lead. In a population of 30,357 patients, 2,298 patients are enrolled in a prospective follow‐up Multicenter Study, the remainder are patients with known clinical status from voluntary reporting, and 2,992 patients died following implant. In the remaining 27,365 patients, 6 deaths have been attributed to J‐wire related injury (J‐inj) while 13 were complications (E‐inj) associated with 4,076 lead extraction procedures (3,974 intravascular (intra)/ 102 primary thoracotomy (PT). The date of occurrences were from 1994 to November 1997. Conclusions: (1) Since lead extractions were not conducted in a controlled study, it is not known whether the deaths associated with lead extraction is in excess of what would have occurred if these leads had not been removed in this specific subset.
Kaplan‐Meier Analysis of Freedom from Extraction or Death in Patients with an Accufix J Retention Wire Atrial Permanent Pacemaker Lead: A Potential Management Tool
Authors: KAWANISHI DAVID T. , BRINKER JEFFREY A. , REEVES RUSSELL , KAY G. NEAL , GROSS JAY , PIOGER GUY , PETITOT JEAN‐CLAUDE , ESLER ANNE , GRUNKEMEIER GARY
Published: July 2006

Morbidity (36 cases) and mortality (6 cases) have been reported in patients with Accufix J retention wire atrial leads. This has resulted in ongoing patient fluoroscopic monitoring as well as lead extractions. The estimated implanted worldwide population is 40,860. Estimating the size of the remaining population at risk is an important tool for assessing patient management guidelines. Results: The Kaplan‐Meier method can be used to calculate the cumulative probability of remaining free of extraction and death for patients based on implant duration. The individual Kaplan‐Meier curves for lead extraction and patient survival can also be computed. Based on the Multicenter Study (MCS) population of 2,298 patients, the probability that a patient is alive with the lead still implanted at 5 years implant duration is 52.5%. The event‐free survival rate at 5 years implant duration is 81.3%. The corresponding probability of remaining free from injury due to the J‐wire is 99.9% at 5 years implant duration. Assuming similar rates of death and extraction, these results can be extrapolated to the world wide population. Conclusions: The management of Accufix patients must consider patient longevity, the probability of J‐wire morbidity/mortality, and the probability of extraction complication morbidity/mortality. The probability of remaining at risk as a function of time from implant can be calculated from the events known in the MCS patient population. These event‐free survival estimates can be used to identify subsets of the population at greater or lesser risk based on various clinical parameters.
Cumulative Hazard Analysis of J‐Wire Fracture in the Accufix Series of Atrial Permanent Pacemaker Leads
Authors: KAWANISHI DAVID T. , BRINKER JEFFREY A. , REEVES RUSSELL , KAY G. NEAL , GROSS JAY , PIOGER GUY , PETITOT JEAN‐CLAUDE , ESLER ANNE , GRUNKEMEIER GARY
Published: July 2006

To permit a more complete analysis of J‐wire fracture in the Accufix series of atrial permanent pacemaker leads, the time to occurrence of all known fractures and injuries has been redefined relative to the duration of risk exposure, that is, according to the interval of time between implant and occurrence of the event. This redefinition permits application of a cumulative hazards model to the data, which previously has not been explored. Predictors of J‐wire fracture can be tested using this method. This also permits parametric curve‐fitting for determination of linearity or constancy of risk of events over time. Results: Among 2,063 Multicenter Study (MCS) leads analyzed, 381 fractures of the J‐wire were identified. Stratified analysis based on cumulative hazard curves identified a more open shape of the J‐wire as predictive of fracture, which supports the results previously reported based on logistic regression analysis. Fitting a Weibull curve to the cumulative hazard of J‐wire fracture gives a shape parameter equal to 0.85. This value indicates that the instantaneous hazard of J‐wire fracture decreased over time from implant. Conclusions: (1) The cumulative hazard function can be used to examine predictors of J‐wire fracture and preliminary findings support the previously identified predictor of J shape; (2) Based on these analyses, the rate of J‐wire fracture appears to decrease slightly as time from implant increases.