bluuebunny/crossref_metadata_2025 huggingface dataset:
Left Ventricular Lead Insertion Using a Modified Transseptal Catheterization Technique: A Totally Endocardial Approach for Permanent Biventricular Pacing in End‐Stage Heart Failure
Authors: LECLERCQ FLORENCE , HAGER FRANÇOIS‐XAVIER , MACIA JEAN‐CHRISTOPHE , MARIOTTINI CLAUDE‐JEAN , PASQUIÉ JEAN‐LUC , GROLLEAU ROBERT
Published: July 2006

This article describes a new technique of LV lead insertion, using transseptal catheterization performed through the right internal jugular vein, to obtain a totally endocardial biventricular chronic pacing in end‐stage heart failure. Three patients with QRS widening (> 180 ms) linked to complete left bundle branch block (n = 2) or right ventricular pacing (n = 1) were included in this preliminary study. Catheterization was performed under fluoroscopy and transesophageal echocardiography guidance. Transseptal catheterization was achieved by puncture of the right internal jugular vein at the base of the neck and by using a Brockenbrough needle, the tip curve of which was more curved than the standard model. A flexible long sheath was advanced in the left atrium through the interatrial septum and then a unipolar electrode was placed easily in the LV. The proximal tip of the LV lead was tunneled from the neck to the subclavian area and connected to the ventricular channel of a dual (n = 1) or simple (n = 2) chamber pacemaker. Efficient acute sensing (V wave amplitude = 13 ± 3 mV) and pacing (acute pacing threshold = 0.7 ± 0.4 V) were obtained in the three patients. Early loss of capture occurred in two patients requiring lead replacement. Functional status dramatically improved in all three patients. At 6‐month follow‐up, biventricular pacing was maintained in all patients (mean threshold 1.4 V) who were free of clinical embolic event with oral anticoagulation therapy. This modified technique of jugular transseptal catheterization appears promising for the development of left heart pacing.
Driving Safety Among Patients with Neurocardiogenic (Vasovagal) Syncope
Authors: BHATIA ATUL , DHALA ANWER , BLANCK ZALMEN , DESHPANDE SANJAY , AKHTAR MASOOD , SRA JASBIR
Published: July 2006

The purpose of this study was to evaluate the risk of injury due to syncope while driving and the driving habits of patients with neurocardiogenic (vasovagal) syncope. Neurocardiogenic syncope is one of the most common causes of syncope. However, the important issue of driving related injury due to syncope in this population is not well defined. Risk of injury due to syncope while driving and driving behavior was evaluated in 155 consecutive patients (92 women and 63 men; mean age 49 ± 19 years) with history of syncope in whom hypotension and syncope or presyncope could be provoked during head‐up tilt testing. Patients with syncope and positive head‐up tilt table test were treated with pharmacological therapy. All participants were asked to fill out a detailed questionnaire regarding any driving related injuries and their driving behavior before tilt table testing and during follow‐up. Prior to head‐up tilt testing two patients had syncope while driving, and one of these patients had syncope related injury during driving. The mean duration of syncopal episodes was 50 ± 14 months (range 12–72 months). Of the 155 patients, 52 (34%) had no warning prior to syncope, while 103 (6%) had warning symptoms such as dizziness prior to their clinical syncope. Following a diagnosis of neurocardiogenic syncope established by head‐up tilt testing, six patients stopped driving on their own. During a median follow‐up of 22 months recurrent syncope occurred in five (3.2%) patients. No patient had syncope or injury during driving. In conclusion, syncope and injury while driving in patients with neurocardiogenic syncope is rare. The precise mechanism of this is unclear but may be related to posture during driving. Consensus among the medical community will be needed to provide specific guidelines in these patients.
Bipolar Ventricular Far‐Field Signals in the Atrium
Authors: FRÖHLIG GERD , HELWANI ZARAH , KUSCH OLIVER , BERG MONIKA , SCHIEFFER HERMANN
Published: July 2006

In an attempt to evaluate the prevalence and predisposing factors of bipolar ventricular far‐field oversensing, 57 patients were studied who had a Medtronic dual chamber pacemaker implanted (models 7940: n = 6; 7960i: n = 41; 401: n = 3; 8968i: n = 7) and bipolar atrial leads with a dipole spacing from 8.6 to 60 mm attached to various parts of the atrial wall (lateral/anterior: n = 30; appendage: n = 10; atrial septum: n = 10; floating: n = 7). Median bipolar sensing threshold for P waves was 4.0 mV (2.8–4.0 mV, lower and upper quartile) with standard leads and 0.35 (0.25–1.4) mV with single pass (VDD) devices. At the highest sensitivity available, 43 of 50 DDD pacemakers but only two of seven VDD systems detected intrinsic R waves in the atrium (P < 0.01). Ventricular far‐field oversensing occurred at 0.5 mV in 28 (56%) and at 1.0 mV in 16 of 50 DDD units (32%), respectively, and there was one observation in a septal implant at a sensitivity of even 2.8 mV. With ventricular pacing, VDD systems were as susceptible to far‐field signals as DDD pacemakers. Outside the postventricular blanking period (100 ms), evoked R waves were detected by 27 of 57 systems (47%) at maximum atrial sensitivity, by 10 (18%) at 0.5 mV, and by 2 (4%) at a setting of 1.0 up to 1.4 mV, respectively. There was no definite superiority of any lead position, there was a trend in favor of the atrial free wall for better intrinsic R wave rejection, but just the opposite was the case for paced ventricular beats. Bipolar signal discrimination tended to be higher with short tip‐to‐ring spacing (17.8 mm) but the difference to larger dipole lengths (30–60 mm) was not significant in terms of the R to P wave ratio and the overall far‐field susceptibility. In summary, bipolar ventricular far‐field oversensing in the atrium is common with short postventricular blanking times and high atrial sensitivity settings that may be warranted for tachyarrhythmia detection and mode switching. A potentially more discriminant effect of shorter dipole lengths (≤ 10 mm) remains to be tested.
Safety Seat Belt Use in Japanese Patients with a Pacemaker
Authors: SAKAKIBARA YUZURU , MITSUI TOSHIO
Published: July 2006

The aim of this study was to evaluate whether the rate of seat belt use is influenced by the interaction between the seat belt shoulder strap and pacemaker generator. The participants (1,942 Japanese patients with pacemakers) were asked to respond to a questionnaire about their seating position in the vehicle, their actual use of seat belts, and the reasons for not wearing seat belts. Front seat occupants (drivers and front seat passengers) were divided into two groups according to the relation between the site of the seat belt shoulder strap and the pacemaker implantation site: group‐1—seat belt ipsilateral to the pacemaker, and group‐2—seat belts contralateral to the pacemaker. Of the 1,942 questionnaires sent by mail, 1,486 (76.5%) were completed and returned. The actual rates of seat belt use were as follows: drivers (n = 428), 67.4% in group 1 versus 81.0% in group 2 (P < 0.01): front seat passengers (n = 403), 63.7% in group 1 versus 70.1% in group 2 (NS); rear seat passengers (n = 655), 26.6%. Among the front seat occupants, pain or an uncomfortable sensation were stated in 59.0% of group 1 versus 30.7% of group 2 (P < 0.01). The interaction between seat belts and pacemaker lowers the rate of seat belt use in patients with pacemakers. Pain or discomfort from seat belt‐pacemaker contact was noted as the reason for not wearing a seat belt. Physicians should inquire about and take into account a patient's seating location in the vehicle and the location of the seat belt shoulder restraint. The pacemaker implantation site should be placed, if possible, contralateral to the seat belt.
Microwave Ablation of Atrial Flutter
Authors: ADRAGÃO PEDRO , PARREIRA LEONOR , MORGADO FRANCISCO , BONHORST DANIEL , SEABRA‐GOMES RICARDO
Published: July 2006

Radiofrequency (RF) ablation of the isthmus between the inferior vena cava and the tricuspid ring has proven to be a safe and successful method of treating atrial flutter (AF). However, RF ablation lesions are small in size requiring a considerable number of energy applications to ablate the AF circuit. The aim of this study was to evaluate the feasibility and efficacy of microwave energy for AF ablation. We report a case of sustained typical AF treated successfully and safely by 1 pulse of microwave (MW) energy. This showed it is possible to treat AF with a small number of pulse applications.
Multicenter Evaluation of Implantable Cardioverter Defibrillator Testing after Implant: The Post Implant Testing Study (PITS)
Authors: BRODSKY CRAIG M. , CHANG FANG , VLAY STEPHEN C. ,   Post Implant Testing Study Investigators
Published: July 2006

To reassess the function of the implantable cardioverter defibrillator (ICD) many electrophysiology centers perform a second test after the initial test at implant. A prospective multicenter study evaluated the necessity and yield of routine postimplant defibrillator testing. The results of 843 postimplant defibrillator tests were collected from 31 centers. The 764 routine tests in which ventricular fibrillation was successfully induced were analyzed. Variables examined included patient age, presenting arrhythmia, underlying heart disease, left ventricular ejection fraction, defibrillator age, make and model of ICD, electrode system, defibrillation threshold, polarity, and waveform. The overall failure rate was 3.1% (24/764). Units tested later than 365 days after implant tended to have a higher failure rate than those tested within the first month or the next eleven months (6.5%, 3.0%, 2.3%, respectively, P = 0.374). The failure rate was higher in patients with left ventricular ejection fraction < 40% than those with higher ejection fractions (3.8% vs 2.0%, P = 0.167). These trends did not reach statistical significance. No other baseline characteristic was associated with higher failure rates. Routine testing of ICDs reveals an overall failure rate of 3.1%. While the rate was low, defibrillator failure places the patient at high risk for sudden cardiac death. As any failure in this population is associated with a high risk of sudden cardiac death, routine defibrillator testing may be justified.
Effects of Proximal Ventricular Septal Pacing on Hemodynamics and Ventricular Activation
Authors: TAKAGI YASUSHI , DUMPIS YANIS , USUI AKIHIKO , MASEKI TAKASHI , WATANABE TAKASHI , YASUURA KENZO
Published: July 2006

Recently the use of alternate site pacing to improve cardiac function in patients with bradyarrhythmias has increased. In the present study, hemodynamics of right ventricular septal pacing were studied in seven dogs. A bipolar screw‐in lead and endocardial lead were placed in the proximal right ventricular septum and right ventricular apex, respectively. The right ventricle was paced from each site. A conductance catheter and Millar catheter were inserted into the left ventricle to determine the left ventricular pressure and the pressure–volume loop. Cardiac output was measured using the thermodilution method. In five of the seven dogs, ventricular activation was documented by isochronal epicardial activation mapping during each pacing mode. Mean arterial pressure and cardiac output during septal pacing were significantly higher than during apical pacing (110 ± 17 mmHg vs 100 ± 18 mmHg; 1.00 ± 0.39 L/min vs 0.89 ± 0.33 L/min). The positive dp/dt during septal pacing was significantly higher than during apical pacing (2137 ± 535 mmHg/s vs 1911 ± 404 mmHg/s). End‐systolic elastance during septal pacing was significantly higher compared to apical pacing (13.1 ± 0.3 mmHg/mL vs 8.9 ± 4.0 mmHg/mL). The ventricular activation time during septal pacing was significantly shorter than during apical pacing. The epicardial maps generated during septal pacing were similar to those from atrial pacing. We conclude that hemodynamics and interventricular conduction are less disturbed by proximal right ventricular septal pacing than apical pacing in dogs with normal hearts.
Transvenous Cardioverter Defibrillator Lead Malfunction Due to Terminal Connector Damage in Pectoral Implants
Authors: MERA FERNANDO , DELURGIO DAVID B. , LANGBERG JONATHAN J. , MOSS ELIZABETH A. , LEÓN ANGEL R.
Published: July 2006

Lead failure places patients with implantable cardioverter defibrillators (ICD) at risk for sudden cardiac death or results in delivery of inappropriate shocks. This study describes a mechanism of lead malfunction occurring at the junction of the terminal ring with the conductor coil of the rate sensing terminal connector in one specific model of a transvenous ICD lead. We detected the problem in a population of 179 patients with a mean age of 61 ± 10 years and a mean lead implant duration of 16 ± 11 months. All patients underwent pectoral ICD implantation using a submuscular approach. The implanting physician chose to place the ICD on the left side in 155 patients (87%) and on the right side 24 patients (13%). Cephalic vein cutdown provided central venous access in 147 patients (82%), and sub‐clavian vein puncture provided access in 32 patients (18%). Follow‐up examination detected lead failure in six patients (3.5% over 31 months) due to insulation damage with or without conductor coil fracture at the junction of the terminal ring and conductor coil of the IS‐1 rate sense terminal. We detected lead disruption 17 ± 9 months (range 5–31 months) after implantation. Multiple nonsustained arrhythmia episodes exhibiting nonphysiologic intervals associated with noisy rate sensing electrograms during pocket manipulation led to discovery in three patients. The other three patients presented with inappropriate device discharges confirmed by stored high‐energy lead electrograms showing normal rhythm. Pacing lead impedance abnormally dropped in two patients. Impedance remained stable in the other four patients. In conclusion, the generator pocket represents an important site of ICD transvenous lead vulnerability. Lead failure may result from conductor coil and/or insulation disruption at the interface with the rate sensing terminal connector.
Patients Over 100 Years of Age with Implanted Cardiac Pacemakers
Authors: FIANDRA ORESTES , BANIZI PABLO FERNANDEZ , FIANDRA H. ALFREDO , FIANDRA DANIEL , ERRAMUN BERNARDO , ESPASANDIN WALTER
Published: July 2006

Ten patients of the authors' practice who have survived to be 100 years of age or more have had an implanted pacemaker for an average of 11.4 years. As the life expectancy of the country (Uruguay) is 75 years, their survival is considered to be unusual, confirming the statistical conclusion that patient survival with an implanted pacemaker may be expected to be as good or better than those who do not require a pacemaker implant.
Intrapulmonary Artery and Intrabronchial Migration and Extraction of a Fragment of J‐Shaped Atrial Pacing Catheter
Authors: TATOU E. , LEFEZ C. , REYBET‐DEGAT O. , WOLF J.E. , LOUIS P. , FAVRE J.P. , DAVID M.
Published: July 2006

A fragment of a fractured Telectronics Atrial Accufix 330–801 lead asymptomatically perforated the adjacent bronchus and was detected on routine chest X‐ray. The metallic fragment was located by chest CT scan and bronchial fluoroscopy to lie between the right lobar bronchus and the pulmonary artery, confirming bronchial perforation. The foreign body was removed without complication by direct visualisation with rigid bronchoscopy.
Failure of Left‐Sided Implantable Cardioverter Defibrillator Implantation Due to Absence of Left Brachiocephalic Vein
Authors: ANTONELLI DANTE , FREEDBERG NAHUM ADAM , ROSENFELD TIBERIO
Published: July 2006

Implantation of an implantable cardioverter defibrillator by the transvenous approach was impossible from the left side in a patient with an absence of the left brachiocephalic vein; the left subclavian vein was connected by a large left superior intercostal vein to the accessory hemiazygos vein that joined the azygos vein; then the blood flowed into the superior vena cava. Implantation was successfully attempted using the right‐sided venous access.
High Impedance Low Energy Pacing Leads: Long‐Term Results With a Very Small Surface Area Steroid‐Eluting Lead Compared to Three Conventional Electrodes
Authors: MORACCHINI PIER VITTORIO , CORNACCHIA DANIELE , BERNASCONI MARCO , TESORIERI MARIA CRISTINA , FABBRI MAURO , MARZEGALLI MAURIZIO , BARALDI PAOLO , CORTE TIZIANO , GIULIANI MAURO , MAROTTA TIZIANA , DE SETA FRANCESCO
Published: July 2006

We evaluated the handling performance at implant, and the long‐term atrial and ventricular electrical performance of a new generation using a very small surface area (1.2 mm2) steroid‐eluting electrode (Medtronic CapSure Z). We compared the performance of CapSure Z to that of traditional passive fixation leads, with and without steroid elution. The study was conducted during 2 years of follow‐up. We studied 188 patients (105 males and 83 females; mean age 71 ± 7 years). All of the patients were implanted with a dual chamber pacemaker and the same type of lead in both chambers. Forty‐one patients received CapSure Z leads, 25 patients received Target Tip leads (8‐mm2 surface area; no steroid elution), 63 patients received CapSure leads (8‐mm2 surface area; steroid elution), and 59 patients received CapSure SP leads (5.8‐mm2 surface area; steroid elution). The four groups were homogeneous in regards to sex, age, cardiac disease, and reason for implant.At follow‐up, the CapSure Z lead showed sensing values comparable to the other leads, with lower pacing thresholds and higher pacing impedance in both chambers. We evaluated the mean current drained from the pacemaker by the different types of leads when using safe, low energy output settings. We found that by using CapSure Z leads, the mean current was significantly lower than that of the other types of leads (0.42 μA for CapSure Z ventricular lead vs 0.85 for CapSure SP, 1.42 for CapSure, and 1.54 for Target Tip). Thus, the use of the CapSure Z lead, combined with low energy output programming, will increase pacemaker longevity compared to the use of traditional leads and standard output programming.
Temperature Response Following Nontraumatic Low Power Radiofrequency Application
Authors: SCHUMACHER BURGHARD , EICK OLAF , WITTKAMPF FRED , VON PEZOLD CAROLIN , TEBBENJOHANNS JÜRGEN , JUNG WERNER , LÜDERITZ BERNDT
Published: July 2006

A marker for the efficiency of heating would be helpful in radiofrequency ablation of tachyarrhythmias. We hypothesized that changes of the catheter tip temperature during nontraumatic, very low power radiofrequency exposure would correlate with the temperature achieved during radiofrequency ablation, and therefore, could be used as a marker for heating efficiency. In 71 ablation attempts for drug refractory supraventricular tachycardias, the catheter tip temperature response to a 1‐W‐5‐second test pulse was measured. Subsequently at the same site, radiofrequency current was delivered with a target temperature of 70°C and a power limit of 50 W. The test pulse, with a measured power level of 1.62 ± 0.28 W, resulted in a heating efficiency of 0.78 ± 0.60°C/W. During ablation, the achieved tip temperature was 52.9 ± 7.5°C, requiring a power output of 40.7 ± 10.9 W. The heating efficiency was 0.57 ± 0.74°C/W. The correlation between heating efficiency at low power and during radiofrequency ablation was linear with a correlation coefficient of 0.88. Regression analysis demonstrated that a heating efficiency above 1°C/W predicts a mean ablation temperature above 50°C with more than 95% confidence interval. The temperature response to a very low power radiofrequency application correlates with the temperature rise achieved during radiofrequency ablation. It is suggested that delivery of low power radiofrequency current could be used to determine and monitor efficiency of heating during catheter mapping and ablation procedures.
“Sagging Heart Syndrome”: A Cause of Acute Lead Dislodgment in Two Patients
Authors: ISKOS DEMOSTHENES , LURIE KEITH G. , SHULTZ JEFFREY J. , FABIAN WILLIAM H. , BENDITT DAVID G.
Published: July 2006

Acute passive fixation atrial lead dislodgment occurred due to an unexpected and marked postural descent of the heart after permanent pacemaker implantation in two patients. Sagging of the heart in these two individuals may have been related to a history of morbid obesity followed by weight loss of over 100 pounds. Lead replacement with active fixation leads was required in both cases. The term “sagging heart syndrome” is proposed to describe this clinical entity. In certain adult populations, such as in patients with a history of significant weight loss, the “sagging heart syndrome” may represent a previously unrecognized cause of acute lead dislodgment.
Supraventricular Tachycardia Terminated by External Mechanical Stimulation: A Case of “Pothole Conversion”
Authors: WONG M.P. , ARMSTRONG P.W.
Published: July 2006

Supraventricular tachycardia requires atrial or AV junctional tissue for its initiation and maintenance. Acute management of supraventricular tachycardias include vagal maneuvers, pharmacological treatment, and electrical cardioversion. We describe a case of a supraventricular tachycardias cardioverted by the jolt of the ambulance hitting a pothole. The proposed mechanism of cardioversion is an external mechanical one similar to the precordial thump.
Catheter Ablation in a Patient with a Congenital Giant Right Atrial Diverticulum Presented as Wolff‐Parkinson‐White Syndrome
Authors: GAITA FIORENZO , HAISSAGUERRE MICHEL , SCAGLIONE MARCO , JAIS PIERRE , RICCARDI RICCARDO , LAMBERTI FILIPPO , CALÒ LEONARDO
Published: July 2006

A young woman symptomatic for tachycardia showed right ventricular preexcitation on the surface ECG with a pattern during induced atrial fibrillation suggestive of multiple APs. Noninvasive imaging techniques performed prior to catheter ablation demonstrated the presence of a giant right atrial diverticulum confirmed by hemodynamic procedure. This structure functioned as an enormous accessory AP. We performed catheter ablation of this pathway using a special 4‐mm multipolar catheter inside the diverticulum. This is the first case of such an anomaly being successfully treated with catheter ablation.
Antidromic Reciprocating Tachycardia in Patients with Paraseptal Accessory Pathways: Importance of Critical Delay in the Reentry Circuit
Authors: MAN DAVID C. , SARTER BRIAN H. , COYNE ROBERT F. , CALLANS DAVID J. , SCHWARTZMAN DAVID , GOTTLIEB CHARLES D. , MARCHLINSKI FRANCIS E.
Published: July 2006

Previous studies in patients with antidromic reciprocating tachycardia (ART) have observed a critical anatomic requirement (> 4 cm) between an antegrade bypass tract limb and a retrograde AV nodal limb. We report two patients with ART utilizing a paraseptal accessory pathway. In both cases, a critical degree of slow conduction within the circuit provides unusual electrophysiologic substrate to overcome the expected anatomical constraints.
Torsade de Pointes Ventricular Tachycardia During Low Dose Intermittent Dobutamine Treatment in a Patient with Dilated Cardiomyopathy and Congestive Heart Failure
Authors: LA VECCHIA LUIGI , OMETTO RENATO , FINOCCHI GIUSEPPE , VINCENZI MARIO
Published: July 2006

The authors describe the case of a 56‐year‐old woman with chronic, severe heart failure secondary to dilated cardiomyopathy and absence of significant ventricular arrhythmias who developed QT prolongation and torsade de pointes ventricular tachycardia during one cycle of intermittent low dose (2.5 mcg/kg per min) dobutamine. This report of torsade de pointes ventricular tachycardia during intermittent dobutamine supports the hypothesis that unpredictable fatal arrhythmias may occur even with low doses and in patients with no history of significant rhythm disturbances. The mechanisms of proarrhythmic effects of Dubutamine are discussed.
Reduction of Atrial Fibrillation Inducibility by Radiofrequency Ablation: An Experimental Study
Authors: CHORRO‐GASCÓ FRANCISCO J. , EGEA SANTIAGO , MAINAR LUIS , CÁNOVES JOAQUÍN , LLAVADOR ESTEBAN , SANCHIS JUAN , SUCH LUIS , LÓPEZ‐MERINO VICENTE
Published: July 2006

A study is made of the antifibrillatory effects of radiofrequency (RF)‐induced atrial lesions using nine Langendorff‐perfused rabbit hearts in which the atrial electrophysiological properties and atrial fibrillation (AF) inducibility were modified by atrial stretching. Using a multiple electrode consisting of 121 unipolar electrodes, determinations were made of the atrial refractory periods, conduction velocity, wavelength of the atrial activation process, and the inducibility of sustained AF episodes (duration over 30 s) by atrial burst pacing in four situations: (a) control; (b) following dilatation of the right atrium; (c) after adding an RF linear lesion at the cava‐tricuspid annulus isthmus; and (d) after adding two RF linear lesions rounding the base of the right atrial appendage and extending from the inferior zone of the sulcus terminalis to the anterior wall of the appendage. Under control conditions, AF was not induced in any of the experiments. The wavelengths were 10.5 ± 1.2 cm for basic cycles of 250 ms and 6.6 ± 0.5 cm for cycles of 100 ms. Following dilatation, a significant decrease was recorded in the atrial refractory periods, conduction velocity, and wavelength, which reached values of 6.1 ± 0.7 cm (250‐ms cycle, P < 0.01), and 3.9 ± 0.3 cm (100‐ms cycle, P < 0.01); AF was induced in five cases (P < 0.05). After producing the lesion at the cava‐tricuspid isthmus, the electrophysiological modifications induced by atrial dilatation persisted (wavelength = 6.2 ± 0.6 cm (250‐ms cycle) and 4.3 ± 0.3 cm (100‐ms cycle); P < 0.01 vs the control) and AF was triggered in eight cases (P < 0.0001). In turn, on adding the two lesions at the right atrial free wall and appendage, AF was induced only in one experiment (P = NS vs control), and the dilatation‐induced decrease in refractoriness and wavelength was attenuated. Nevertheless, differences remained significant with respect to the controls, with the exception of the functional refractory periods determined at cycles of 100 ms. In this phase, the wavelength was 6.6 ± 0.7 cm (250‐ms cycle, P < 0.01 vs control) and 4.9 ± 0.5 cm (100‐ms cycle; P < 0.05). Atrial conduction between the zones separated by the lesions was blocked at any frequency, or selectively at rapid atrial activation frequencies. In conclusion: (a) the production of three linear lesions in the right atrium (cava‐tricuspid isthmus, atrial appendage, and inferior free wall) reduces AF inducibility in the experimental model used; (b) conduction block (either absolute or frequency dependent) through the lesions, reduction in tissue mass caused by lesion creation, and possibly the attenuation of the shortening of atrial refractoriness and wavelength in the zones not separated by the lesions are implicated in the reduction of AF inducibility; and (c) the single lesion in the cava‐tricuspid isthmus does not impede AF inducibility.
Implantable Defibrillators Impedance Measurement Using Pacing Pulses Versus Shock Delivery with Intact and Modified High Voltage Lead System
Authors: MEHDIRAD ALI A. , STOHR ERICH C. , LOVE CHARLES J. , NELSON STEVEN D. , SCHAAL STEPHEN F.
Published: July 2006

At present the only method for measuring the high voltage system lead impedance in patients with an ICD is to deliver a low energy test shock. This is painful, requires sedation, and carries a risk of ventricular fibrillation induction. We sought to assess the shock lead and electrode function by calculating IMP using low voltage pacing pulses, and compared it to the measured impedance of a shock through the same lead. This was performed in both an intact and a modified lead system in order to mimic common clinical scenarios that alter lead system IMP (e.g., lead fracture). In an anesthesized canine model (n = 12) a standard (S) transvenous defibrillation lead (TDL), a modified (M) TDL (two‐thirds of coil covered with heat‐shrunk tubing), an active can (AC), and a M epicardial patch (EP) (two of four coils were disconnected) were used. Three configurations (C) were tested: C1: S/TDL→AC;, C2: M/TDL→AC;, and C3: M/TDL→MEP. A measured IMP was obtained by an ICD using a 5‐J shock as control. IMP was calculated using a 5‐J shock, pacing pulses of 10‐, 5‐, 2‐, and 1‐V amplitude, as well as from a square wave drive train of low amplitude/high frequency signals (1 and 0.2 V, at 10 kHz) in all Cs. Ohm's law (V = IR) was utilized for measuring calculated IMP. As the surface area of the high voltage lead system decreased, the mean measured IMP (control) increased from C 1 to 3 (63 ± 10, 95 ± 4, and 127 ± 20 Ω, respectively). The correlation of calculated IMP from all Cs to measured impedance (control) remained high throughout the IMP range (range of correlation coefficient (r): 0.921–0.981). Calculated IMP using delivery of pacing pulses is highly correlated to IMP measured during shock delivery. This correlation remains high over a clinically significant range of high voltage lead system IMP changes. This study suggests that pacing pulses can be used to predict the IMP changes in the high voltage lead system which may occur clinically, reducing the need to deliver a shock for IMP measurement.
Modulation of the Atrioventricular Node Conduction to Achieve Rate Control in Patients with Atrial Fibrillation: Long‐Term Results
Authors: CARBUCICCHIO CORRADO , TONDO CLAUDIO , FASSINI GAETANO , RIVA STEFANIA , AGOSTONI PIERGIUSEPPE , GALLI CLAUDIA , BELLA PAOLO DELLA
Published: July 2006

Modulation of the AV node reduces the ventricular rate during AF, without affecting AV conduction during sinus rhythm. Acute and long‐term results of AV node modulation in 75 patients with AF and severe related symptoms of heart failure are presented in this study. The procedure involved, in all cases, the selective ablation of the posterior inputs to the AV node; in a subgroup of 15 patients with poor modification of AV conduction properties, a sequential approach involving subsequent anterior input ablation was performed. The procedure caused acutely a prolongation of the Wenckebach cycle length (38 patients in sinus rhythm) from 334 ± 88 to 470 ± 80 ms (P < 0.01), and a reduction of the average ventricular rate (37 patients in AF) from 154 ± 31 to 88 ± 40 beats/min (P < 0.01); permanent complete AV block was induced in 9 of 75 patients (12%). Considering the “sequential” approach, an increase of the Wenckebach cycle length from 362 ± 50 to 530 ± 45 ms (P < 0.01) and a reduction of the average heart rate in patients with AF from 158 ± 16 to 81 ± 20 beats/min (P < 0.01) was obtained in this subgroup of patients, in whom the AH interval prolonged from 93 ± 12 to 175 ± 27 ms, and no complete AV block was observed. At a mean follow‐up of 23 ± 9 months (range 2–48), the mean number of hospital admissions per patient per year decreased from 4.2 to 0.2. Five of 49 patients with paroxysmal AF and 3 of 26 patients with chronic AF had high rate recurrences (1 > 120 beats/min) that caused severe palpitations; these patients were considered as late clinical failures (8/75; 11%). All patients reported a substantial subjective improvement and an increased exercise tolerance, as documented by a semiquantitative questionnaire. There were no episodes of late AV block or sudden cardiac deaths. In conclusion, modulation of the AV node—either by slow pathway ablation, or by a “sequential” posterior and anterior approach in refractory patients—allows a long‐term control of the ventricular rate and prevents the recurrence of severe clinical symptoms in more than 75% of patients with drug refractory AF.
Quality of Life in Patients with Complete Heart Block and Paroxysmal Atrial Tachyarrhythmias: A Comparison of Permanent DDIR versus DDDR Pacing with Mode Switch to DDIR
Authors: PROVENIER FRANK , BOUDREZ HEDWIG , DEHARO JEAN CLAUDE , DJIANE PIERRE , JORDAENS LUC
Published: July 2006

A prospective double‐blind randomized crossover study was done in 15 patients with complete heart block and intermittent ATs. The pacemaker was randomly programmed to dual chamber inhibited rate responsive pacing (DDIR) and to DDDR with mode switch, for 1 month each. An event recorder was given to the patients and after each period, a QOL questionnaire was obtained. Based on telemetric data, all but two patients had AT during follow‐up. The duration and frequency of these episodes were not related to mode settings. AV synchrony was better preserved in DDDR (P < 0.05). Most symptom‐related event recordings during DDIR showed loss of AV synchrony; DDDR with mode switch caused symptoms due to tracking of ST. Overall the QOL score was not different between the modes. Fewer somatic complaints were noted during DDDR pacing than during baseline. DDIR stimulation showed no difference. Twelve patients preferred the period of DDDR pacing; one experienced severe symptoms during DDIR. In conclusion, patients with paroxysmal A, DDDR with mode switch, and DDIR had no influence on the occurrence, nor on the duration of AT episodes. AV synchrony was better preserved in DDDR, which was also associated with fewer somatic complaints compared to the baseline. In DDDR, symptoms were observed when ST was tracked. QOL was comparable, although more patients preferred DDDR.
Pectoral Cardioverter Defibrillators: Comparison of Prepectoral and Submuscular Implantation Techniques
Authors: MANOLIS ANTONIS S. , CHILADAKIS JOHN , VASSILIKOS VASSILIS , MAOUNIS THEMOS , COKKINOS DENNIS V.
Published: July 2006

The purpose of this study was to compare the two techniques of pectoral ICD implantation, prepectoral and submuscular, performed by an electrophysiologist in the catheterization laboratoty with use of general or local anesthesia in 45 consecutive patients. Over a period of 30 months, we implanted pectoral transvenous ICDs in 43 men and 2 women, aged 59 ± 12 years, with use of general (n = 20) or local (n = 25) anesthesia in the catheterization laboratory. Patients had coronary (n = 30) or valvular (n = 4) disease, cardiomyopathy (n = 10) or no organic disease (n = 1), a mean left ventricular ejection fraction of 31%, and presented with ventricular tachycardia (n = 40) or fibrillation (n = 5). One‐lead ICD systems (18 Endotak, 10 Transvene/8 Sprint, 2 EnGuard) were used in 38 patients, 2‐lead (5 Transvene, 1 EnGuard) systems in 6 patients, and 1 atrioventrirular lead ICD system in 1 patient. The prepectoral technique was employed in 29 patients with adequate subcutaneous tissue, while the sub‐muscular technique was used in 16 patients who had a thin layer of subcutaneous tissue. The defibrillation threshold averaged 9–10 J in both groups and there were no differences in pace/sense thresholds. All implants were entirely transvenous with no subcutaneous patch. Biphasic ICD devices were employed in all patients. Active or hot can devices were used in 39 patients. There were no complications, operative deaths, or infections. Patients were discharged at a mean of 3 days. All devices functioned well at predischarge testing. Over 14 ± 8 months, 20 patients received appropriate device therapy (antitachycardia pacing or shocks). No late complications occurred. One patient died at 3 months of pump failure; there were no sudden deaths. In conclusion, for exclusive pectoral implantation of transvenous ICDs, electrophysiologists should master both prepectoral and submuscular techniques. One can thus avoid potential skin erosion or need for abdominal implantation in patients with a thin layer of subcutaneous tissue. Finally, there are no differences in pacing or defibrillation thresholds between the two techniques.
Effect of a Class III Antiarrhythmic Drug on the Configuration of Dose Response Curve for Defibrillation
Authors: MURAKAWA YUJI , YAMASHITA TAKESHI , KANESE YUKIHIRO , OMATA MASAO
Published: July 2006

Antiarrhythmic agents with a Class III action are known to increase defibrillation efficacy. We investigated whether a Class III drug simply shifts the dose‐response curve for defibrillation or more extensively alters the curve. Forty‐five dogs were divided into four groups according to the shock waveform and the presence or absence of treatment with a novel Class III drug, MS‐551 (2 mg/kg bolus + 0.02 mg/kg per min). In addition to the conventional transcardiac DFT, dose‐response curves were obtained by fitting the results of 40 fibrillation‐defibrillation sequences at five shock strengths to a logistic model. MS‐551 significantly decreased DFT regardless of the shock waveform (control vs MS‐551 = 306 ± 79 V vs 229 ± 72 V [monophasic shock, P < 0.05], or 227 ± 42 V vs 176 ± 26 V [biphasic shock, P < 0.005]). The dose‐response curves in dogs treated with MS‐551 had a gentler slope than those without treatment, and the ratio of the voltages corresponding to 50% and 90% defibrillation success (V90/V50) was significantly greater in the MS‐551 group (monophasic: 1.21 ± 0.06 vs 1.62 ± 0.42 [P < 0.005], biphasic: 1.20 ± 0.05 vs 1.37 ± 0.18 [P < 0.01]). The V90/DFT ratio was also significantly larger in the MS‐551 group (monophasic: 1.22 ± 0.12 vs 1.66 ± 0.37 (P < 0.001); biphasic: 1.19 ± 0.11 vs 1.44 ± 0.79 [P < 0.005]). Thus, this Class III drug decreased the shock strength corresponding to relatively higher success rate (˜90%) less markedly than that for moderate success rate (˜50%). These results suggest that a Class III drug does not simply shift the dose response curve in proportion to the change in DFT, but more extensively alters its configuration.
Sustained Inhibition of a DDD Pacemaker at Rates Below the Programmed Lower Rate During Automatic PVARP Extension
Authors: BAROLD S. SERGE
Published: July 2006

A patient with a Pacesetter Paragon III DDD pacemaker exhibited sustained pacemaker inhibition at rates below the programmed lower rate during sinus rhythm with marked first degree AV block. In this device, a pacemaker defined ventricular extrasystole initiates automatic extension of the postventricular atrial refractory period to 480 ms and the atrial escape interval to 830 ms regardless of the programmed lower rate. Sustained pacemaker inhibition at rates below the programmed lower rate occurred because the P wave fell continually in the extended postventricular atrial refractory period, and the conducted QRS complex initiated a pacemaker ventricular extrasystole response with atrial escape interval extension. This process continued as long as the P wave stayed within the extended postventricular atrial refractory period, no ventricular extrasystole disrupted the sequence, and the R‐R interval of spontaneous beats was shorter than the extended atrial escape interval. Such a pacemaker response should not be misinterpreted as device malfunction.
Pacemaker‐Induced Superior Vena Cava Obstruction: Bypass Using the Intact Azygous Vein
Authors: CHIA HENDRICK M.Y. , ANDERSON DAVID , JACKSON GRAHAM
Published: July 2006

Superior vena cava thrombosis due to pacemaker leads is an uncommon but well‐recognized complication. Its pathogenesis remains unclear and it is usually a benign condition. Superior vena cava occlusion can be successfully treated by thrombolysis and anticoagulation if the occlusion is recent, balloon venoplasty and stenting, and surgery. We describe a case of superior vena cava obstruction successfully bypassed using the intact native azygous vein, a technique that has not been described before, with excellent long‐term results.
Successful Thrombolysis of Right Atrial and Ventricle Thrombi Encircling a Temporary Pacemaker Lead in a Patient with Heparin‐Induced Thrombocytopenia Type II
Authors: JANSSENS U. , BREITHARDT O.A. , GREINACHER A.
Published: July 2006

Only few reports exist addressing the problem of temporary pacemaker leads associated with thromboembolic disease. We report the case of a 67‐year‐old patient who required a temporary transfemoral pacemaker due to AV block grade III. The patient developed extensive right atrial and ventricle thrombus formation attached to the pacing wire, as well as venous thrombosis at the insertion site due to heparin‐induced thrombocytopenia type II (HIT type II). After short‐term thrombolysis with 1 mg rt‐PA/kg b.w. complete resolution of all clots could be shown by B‐mode sonography and transthoracic, as well as transesophageal echocardiography.
Pacemaker Syndrome Induced by the Mode Switching Algorithm of a DDDR Pacemaker
Authors: JAÏS PIERRE , BAROLD S. SERGE , SHAH DIPEN C. , TAKAHASHI ATSUSHI , HOCINI MÉLÈZgrave;E , HAÏSSAGUERRE MICHEL , CLÉMENTY JACQUES
Published: July 2006

A patient with marked first‐degree AV block and a DDDR pacemaker presented with a history of paroxysmal narrow QRS tachycardia, subsequently identified as sinus tachycardia (with a very long PR interval), causing a clinical problem similar to pacemaker syndrome because of loss of AV synchrony. The latter resulted from an excessively long postventricular atrial refractory period (PVARP) that prevented sensing of sinus P waves. The unfavorable hemodynamics caused reflex sinus tachycardia. The long PVARP was mandated by the mode switching algorithm of this particular device and was automatically set according to the selected tachycardia detection rate. The patient became asymptomatic when the mode switching function was turned off and the PVARP shortened.
Does Acute Volume Overloading in the Setting of Left Ventricular Dysfunction and Pulmonary Hypertension Affect the Defibrillation Threshold?
Authors: VIGH ALEXANDER G. , LOWDER JERRY , DEANTONIO HARRY J.
Published: July 2006

The impact of acute volume overload hemodynamics on the DFT with concurrent moderate left ventricular systolic dysfunction is unknown. Ten mongrel dogs (17.2 kg), using a crossover study design, each had baseline (study 1) hemodynamic, echocardiographic, and DFT measurements. These measurements were repeated after left ventricular dysfunction was induced using a norepinephrine (5 μg/kg per min) infusion (study 2). Hemodynamic and DFT parameters were obtained simulating acute heart failure by volume overload with an 0.9% normal saline infusion to an associated mean pulmonary capillary wedge pressure of > 19 mmHg (study 3). Numerous significant echocardiographic and hemodynamic parameters were noted when the animals from studies 1 and 2, 2 and 3, and 1 and 3 were compared. A significant difference in the DFT was observed only when study animals 1 and 3 were compared (P < 0.02). None of the dogs were hypoxemic at the time of the acute heart failure DFT. The mechanism of this finding remains unknown. This data would suggest that acute volume overload with associated left ventricular dysfunction does adversely affect the DFT in a canine model.
Oxygen Uptake to Work Rate Relation Throughout Peak Exercise in Normal Subjects: Relevance for Rate Adaptive Pacemaker Programming
Authors: LEWALTER THORSTEN , RICKLI HANS , MACCARTER DEAN , SCHWARTZE PETER , SCHIMPF RAINER , SCHUMACHER BURGHARD , JUNG WERNER , CANDINAS RETO , LÜDERITZ BERNDT
Published: July 2006

The oxygen uptake to work rate (VO2/WR) relationship observed throughout peak exercise testing is already being applied for rate adaptive pacemaker programming. However, the detailed curve design of VO2/WR with respect to the anaerobic threshold (AT) has not yet been investigated. It was the purpose of this study to determine the VO2/WR slope below and above the AT in a healthy control group. Seventy‐eight healthy control subjects (45.9 ± 17.4 years; 34 women: 49.9 ± 18.6 years 44 men: 43.6 ± 16.6 years) were exercised on a treadmill with “breath‐by‐breath” gas exchange monitoring using the symptom limited “ramping incremental treadmill exercise” (RITE) protocol. The slope of the VO2/WR relationship from rest to peak exercise (r‐p), rest to AT (slope A), and AT to peak exercise (slope B) in mL oxygen uptake per watt of external treadmill work was determined by linear regression analysis.

The oxygen uptake to work rate relationship throughout peak exercise in the entire study group generated a significant slope change at the AT (31%, P < 0.0001) with a decreasing slope during higher work load intensities. Female subjects demonstrated a greater percentage of slope change at AT (43%), as compared to men (22%, P < 0.01). When using the oxygen uptake to work rate relationship for the programming of the pacemaker's rate response to exercise, the significant slope change at the AT should be considered to more appropriately pace during higher work intensities supported by anaerobic metabolism. Female pacemaker patients should be programmed to generate a steeper VO2/WR slope below AT with a greater slope change at AT, as compared to men. Abnormally high oxygen uptake to work rate ratios above the AT may be possibly used as an indicator of overpacing.
Radiofrequency Catheter Ablation of Drug Refractory Symptomatic Ventricular Ectopy: Short‐ and Long‐Term Results
Authors: LAURIBE PHILIPPE , SHAH DIPEN , JAÏS PIERRE , TAKAHASHI ATSUSHI , HAÏSSAGUERRE MICHEL , CLÉMENTY JACQUES
Published: July 2006

We performed radiofrequency catheter ablation (RFCA) in 12 consecutive patients (17–77 years) with daily, symptomatic, monomorphic ventricular ectopy (VE) (12,096 ± 3.326 on 24‐hour Holter) resistant to antiarrhythmic drugs. Nine patients had no apparent structural heart disease, 1 patient had a mild dilated cardiomyopathy, 1 patient had a treated mitral stenosis, and 1 patient had arrhythmogenic ventricular dysplasia. VE morphology was LBBB with inferior axis in 9 patients, RBBB with inferior axis in 2 patients, RBBB with superior axis in 1 patient. None of the patients had spontaneous or inducible sustained ventricular tachycardia. The VE focus was targeted with RF energy at the earliest endocardial activation site and based on a matching 12‐lead ECG pace map. The VE focus was localized in the right outflow tract in 9 patients and on the left ventricle in 3 patients. RFCA was delivered with a standard 4‐mm tip electrode. The ablation was initially successful in 11 patients and unsuccessful in 1 patient. All successfully ablated patients were asymptomatic and discharged without antiarrhythmic drugs. During follow‐up (25 ± 8; 17–38 months), two patients had a recurrence of symptoms, which were controlled by a previously ineffective drug. At the end of follow‐up, 1,329 ± 3198 VE were observed on Holter monitoring (P < 0.001 compared with initial values). No short‐ and long‐term complications were observed. RFCA is a safe and effective method for treating drug‐resistant symptomatic monomorphic VE in carefully selected patients. A persistent benefit without complications was obtained over a 2‐year follow‐up.
An Interesting Case of Infant Sudden Death: Severe Hypertrophic Cardiomyopathy in Pompe's Disease
Authors: METZL JORDAN D. , ELIAS ELLEN R. , BERUL CHARLES I.
Published: July 2006

Glycogen storage disease type II (Pompe's disease) is a rare inherited metabolic disorder, which often leads to infantile death from severe cardiomyopathy. This case of sudden death illustrates the features of the cardiac findings in the disorder, resulting from massive lysosomal accumulation of glycogen in the heart and other tissues. Pompe's disease should be considered in cases of unexplained infantile cardiomyopathy.
Pulmonary Embolization of a Pacing Electrode Fragment Complicating Lead Extraction
Authors: WALTERS M.I. , KAYE G.C.
Published: July 2006

We present a case that demonstrates an unusual complication of electrode extraction, namely asymptomatic embolization of a pacing electrode fragment into the pulmonary vascular bed
Arteriovenous Fistula After Injury of the Left Internal Mammary Artery During Extraction of Pacemaker Leads with a Laser Sheath
Authors: BRACKE FRANK A. , van GELDER BERRY , MEIJER ALBERT
Published: July 2006

The left internal mammary artery was severed and an arteriovenous fistula created during extraction of pacemaker leads with a laser sheath.