bluuebunny/crossref_metadata_2025 huggingface dataset:
Atrial Arrhythmias in Dual Chamber Pacing and Their Influence on Long‐Term Mortality
Authors: DETOLLENAERE MARC , van WASSENHOVE ETIENNE , JORDAENS LUC
Published: July 2006

A retrospective study of 252 patients who received a DDD pacemaker between October 1982 and December 1990 was performed. During a mean follow‐up of 30 months, reprogramming to the VVI mode was necessary in 39 patients (15.5%). Technical problems causing downgrading occurred 15 times, of which 13 problems became permanent. A total number of 24 patients had sustained atrial arrhythmias, including 14 with atrial fibrillation and 10 with atrial flutter. In this group, conversion to sinus rhythm could be obtained in 38%. After 2 years, reliable DDD pacing was maintained in 86% of the surviving patients. The survival after 1 and 2 years was 94% and 89%, respectively, and was not influenced by arrhythmias or technical problems. We conclude that atrial arrhythmias including flutter are the most important reasons for reprogramming to the VVI mode, although in an important number of patients, predominantly those with flutter, restoration of AV synchrony can be obtained. The high number of patients with atrial flutter could imply some role for DDD devices offering the option of antitachycardia pacing. Reprogramming of the pacing mode did not influence mortality.
Use of a New Fallback Function to Prevent Endless‐Loop Tachycardias: First Clinical Results
Authors: NITZSCHÉ R. , GIRODO S. , LIMOUSIN M. , CAZEAU S. ,   THE INVESTIGATORS OF THE MULTICENTER STUDY
Published: July 2006

The methods used for preventing endless‐loop tachycardias (ELTs) most often consist of initiating a long postventricular atrial refractory period (PVARP) with the sensing of every event likely to induce ELTs, such as sensed premature ventricular contractions (PVCs). A new fallback function may be useful to prevent the initiation of ELTs. A window of atrial rate acceleration detection (WARAD) is initiated with the sensing of every sinus event and equals 75% of the preceding PP interval. If an atrial event is sensed during this period, as are premature atrial contractions (PACs), no atrioventricular (AV) delay is initiated, but an atrial puise output is delivered and a subsequent 31‐msec AV delay is started. Theoretically retrograde P waves are premature compared to sinus rhythm. They are therefore detected as PACs, and do not initiate AV delay, thus prohibiting the induction of ELTs. This function was tested in six patients, using external or implanted Chorus 2 pacemakers. Short PVARP (203 msec) and high atrial sensibility were programmed. Retrograde conduction was induced either by inefficient atrial pacing or a long programmed AV delay. Two different dual chamber settings were tested: dual chamber pacing with the fallback function On or Off. In every situation, the function proved effective in preventing ELTs: the number of tachycardia episodes went from 124 with the function programmed Off to 5 with the function programmed On for comparable durations. More than 75 ELTs effectively prevented by fallback have been recorded.
Mixed Microprocessor‐Random Logic Approach for Innovative Pacing Systems
Authors: GAGGINI G. , GARBEROGLIO B. , SILVESTRI L.
Published: July 2006

Modern pacing systems are becoming more and more sophisticated. Conversion of the information supplied by a sensor into suitable parameters for a rate controlling algorithm and the management of complex timing are common tasks for an integrated circuit (IC) in cardiac pacing. An effective solution consists of using a microprocessor to implement algorithms and pacing modes in a flexible way. The key point of using the same hardware resources for different tasks on a time sharing basis allows the design of a less complex 1C when compared to a random logic structure with the same performances. The major design problems in a full microprocessor solution are its relatively low operating speed due to the low frequency clock necessary for low current drain, and the sequential structure of the machine itself. This can lead to unacceptable timing inaccuracy in all situations requiring the management of complex decision trees. In order to take full benefit from the advantages of a microprocessor structure without these drawbacks, a mixed microprocessor‐random logic approach has been investigated. This architecture uses a microprocessor core to perform all high level nonreal‐time operations (setup of the pacing cycle, data reduction and processing, data integrity checks) while a set of random logic peripherals is used for all critical timing aspects.
In Vitro Evaluation of a Sensor Sensitive to Acceleration Forces Included in a New Rate Modulated Pacemaker
Authors: MAHAUX VERONIQUE , VERBOVEN YVES , WALEFFE ANDRE , GRODENT CHRISTOPHE , GERADIN PAUL , KULBERTUS HENRI
Published: July 2006

The characteristics of the sensor and rate adaptive algorithm included in a new dual chamber rate responsive pacemaker (Relay 294–03, Intermedics, Inc.) were studied by submitting the device to calibrated to‐and‐fro movements of specific frequencies and peak accelerations by means of a mechanical arm connected to a speed adapter. Atrial pacing rate was continuously recorded on a Holter monitor. The influences of the frequency, the magnitude, and the axis of the acceleration forces as well as the reproducibility of the rate response were evaluated. Results: (1) the sensor was sensitive to frequencies ranging from 0.5 to 7 Hz with a peak sensitivity at 3 Hz; (2) the pacing rate was not affected during movements at frequencies > 6 Hz, commonly presented as nonactivity related signals fear, bus transportation, drilling); (3) the pacing rate increased as a function of the acceleration magnitude up to 0.5 G (0.3 G for 3 Hz), then remained constant. This level of acceleration usually corresponds to high degrees of activity; (4) rate response was maximum when acceleration was directed in the anteroposterior direction; (5) reproducibility of the rate response was excellent (R2: 0.999; slope of the regression line: 0.999). Conclusion: Relay 294‐03 is a low frequency signal sensing rate modulated pacemaker using an accelerometer sensitive to motion, mainly in the anteroposterior direction.
A Comparison of External Rate Responsive Pacemakers With Identical Implanted Units
Authors: ZARLING JOHN , BELOTT PETER , BROWN DEBORAH , ALLEN JOHN , SIECKHAUS JOHN
Published: July 2006

Seven patients with previously implanted accelerometer‐based DDDR pacemakers had an identically programmed external pacemaker taped onto their chest. Both units underwent a simultaneous test to set the sensitivity of the accelerometer. The units were then programmed to record the pacing rates for a 15‐minute period. The patients underwent an exercise course that included walking and stairs. After the exercise, the patients sat for 3 minutes and the pacing rates from the test were telemetered. The pacing rate was compared at 2 minutes, 4 minutes, peak, and 3 minutes postexercise. The mean standard deviation (SED) for the external pacemaker was 97.9 at 3.53 ppm, 102 at 10.6 ppm, 106 at 8.94 ppm, and 71.3 at 2.29 ppm at 2, 4, peak, and decay, respectively. The mean SEDfor the implanted pacemaker was 98.1 at 5.76 ppm, 100 at 10.2 ppm, 104 8.24 ppm, 72.4 at 2.88 ppm at 2, 4, peak, and decay, respectively. Difference between pacemakers in ppm was 0.286, 2.0, 2.71, and 1.14 at 2, 4, peak, and decay, respectively. A 95% confidence interval in ppm was ‐ 5.28 to 5.85, ‐ 10.1 to 14.1, ‐ 7.30 to 12.7, and ‐ 1.89 to 4.17 at 2, 4, peak, and decay, respectively. In all patients there was a high confidence correlation between the implanted and external unit. An external unit can be used to predict the rate response of an accelerometer‐based pacemaker without any adjustments to the pacing parameters.
Italian Multicenter Study on a Single Lead VDD Pacing System Using a Narrow Atrial Dipole Spacing
Authors: ANTONIOLI G.E. , ANSANI L. , BARBIERI D. , GUARDIGLI G. , PERCOCO G.F. , TOSELLI T.
Published: July 2006

Since November 1988, 514 patients with advanced atrioventricular (AV) block and normal sinoatrial function have received the single lead VDD pacing system Twinal 30 Lem/CCS in 30 Italian centers. At implantation, particular attention was paid to the correct positioning of the atrial dipole in the mid‐ to mid‐high right atrium and to the atrial electrogram characteristics. The follow‐up included a chest X ray, to be performed before discharge of the patient from the hospital, telemetric evaluations of the endoatrial potential, provocative tests for interferences by myopotentials, 24‐hour ambulatory EGG recordings, and where possible, exercise stress tests. The mean follow‐up duration was 15.2 months, ranging from 1 to 42 months. A very low percentage of chronic atrial fibrillation, loss of atrial sensing, and system replacement was reported, most of the patients (93.5%) being paced in VDD mode. All investigations indicated an excellent overall system performance, stable AV synchrony, and infrequent myopotential interference, and a low complication rate throughout the follow‐up period.
Initial Clinical Experience with a Single Pass VDDR Pacing System
Authors: LAU CHU‐PAK , TAI YAU‐TING , LI JOHN PO‐SHAN , CHUNG FELSA LAI‐WAH , SUNG STELLA , YAMAMGTO ALLAN
Published: July 2006

Although ventricular rate adaptive pacing (VVIR) improves exercise capacity and cardiac output compared to constant rate ventricular pacing (WI), this pacing mode does not provide benefit of atrioventricular (AV) synchrony. We evaluated the use of a custom‐built VDDR pacing system using a single pass, ventricular lead, which detects end cavity P wave using a pair of diagonally arranged atrial bipolar (DAB) electrodes. In the VDDR mode, AV synchrony is enabled and the P wave rate is used in conjunction with an accelerometer based activity sensor for rate adaptive pacing. A VDDR pacemaker was implanted in three patients with complete AV block (mean age 63 ± 1 year) and the mean implantation time was 29 minutes. Mean P wave amplitude was 2.4 mV (1.2–4.2 mV) at implantation and telemeter P wave amplitude was stable over a follow‐up of 6 months. At a sensitivity of 0.2 mV, stable P wave sensing was observed during breathing maneuvers, arm swinging, my potential induction, and Holter recording. Paired exercise tests performed in the VDDR and VVIR modes showed higher cardiac output at rest, during exercise, and in the recovery period in the VDDR pacing mode. Thus VDDR pacing using a single pass lead is superior to VVIR pacing by enabling P synchronous ventricular pacing without adding to the complexity of implantation.
Balloon Electrode Catheter for Transesophageal Atrial Pacing and Transesophageal EGG Recording
Authors: HEINKE MATTHIAS , VOLKMANN HANS
Published: July 2006

A new balloon electrode catheter (10 French) with five or six balloon electrodes placed on the cardiac side was developed for transesophageal atrial pacing and bipolar ECG recording. The diameter of the hemispheric electrodes is 6 mm and the length of the esophageal balloon is 10 cm. The transesophageal atrial pacing threshold was measured with the balloon electrode catheter by transesophageal programmed atrial stimulation (TPS) (n = 54). At the onset of TPS, the feeling, capture fn = 54), and pain voltage threshold (n = 6) were measured by increasing the amplitude of the pacing voltage during high rate bipolar atrial pacing and bipolar atrial ECG recording. In 38 TPS, the capture threshold was lower than the feeling threshold (n = 28). In 16 TPS, the capture threshold was higher than the feeling threshold. In conclusion, painless atrial pacing and excellent ECG recording can be achieved with a multipolar esophageal balloon electrode catheter with a low pacing voltage amplitude and a high P wave amplitude.
Is Polyurethane Lead Insulation Still Controversial?
Authors: MUGICA J. , DAUBERT J.C. , LAZARUS B. , HENRY L. , DUCONGE R. , LESPINASSE P.
Published: July 2006

A controversy arose some 10 years ago over the reliability of polyurethane lead insulation. On the basis of one of the longest standing and largest databanks worldwide, the authors compare the cumulative survival of several thousand polyurethane, standard silastic, and high‐performance silastic electrodes as it pertains to the failure criterion described as insulation degradation. With the possible exception of the Medtronic 6972 (Medtronic, Inc.) electrode, polyurethane electrodes have a 100% reliability at 84 months, which is similar to silastic electrodes.
Threshold and Polarization Properties of Modern Active Fixation Atrial Leads
Authors: KINDERMANN MICHAEL , SCHWERDT HOLGER , FRÖHLIG GERD , SCHIEFFER HERMANN
Published: July 2006

The purpose of the study was to compare the stimulation characteristics of two modern active fixation leads (E1a 583F, vitreous carbon tip [ELA] and Intermedics 82–0008–1601, iridium oxide tip [IROX]) with a standard lead (Osypka KY 67 VC, carbon‐covered elgiloy tip [OSY]). In three groups of ten patients each, minimum charge threshold δQmin and polarization properties were determined via charge telemetry of the pacemaker (Intermedics Cosmos II and Relay) 0, 2, 5, 10, 28, 90, and 180 days after implant (dai). The polarization parameters global capacitance Cg, global resistance Rg, polarization voltage Up, and a time constant t* (t*= Cg? Rg) were obtained by nonlinear regression. Up was always significantly (sig) lower in ELA and IROX (0.04–0.10 V) compared to OSY (0.54–0.76 V). Rg was sig lower in ELA (330–437 Ω) compared to OSY and IROX (414–588 Ω) from 0 to 28 dai. From 2 to 10 dai, Cg was sig higher in ELA and IROX (3.8–4.2 μF) compared to OSY (3.3–3.4 μF). In the three groups, BQmin reached a comparable maximum (1–1.2 μC) at 5 dai. Therefore, vitreous carbon and iridium oxide atrial fixation leads exhibit low chronic polarization effects compared to a standard elgiloy lead, but do not show a sig reduction in charge threshold.
Thin Bipolar Leads: A Solution to Problems with Coaxial Bipolar Designs
Authors: ABLER STEVEN C. , FOSTER ARTHUR J. , SANDERS RICHARD S. , WUU EVANS
Published: July 2006

A new type of bipolar lead has been designed to be thinner and more reliable than the standard coaxial design. The new lead has passed numerous bench tests to ensure its reliability. Improved fatigue performance was shown during comparisons between the new type of coil (bifilar DFT [drawn filled tube]) and previous standard coils (trifilar MP35N). During the initial animal studies no reliability concerns were raised and stable electrode thresholds were measured. If success in the test process of this lead continues, a bipolar lead may soon be marketed with a size and reliability comparable to unipolar leads.
Pacing Lead Survival: Performance of Different Models
Authors: WOSCOBOINIK JAVIER R. , MALONEY JAMES D. , HELGUERA MARCELO E. , MERCHO NAWWAR , ALEXANDER LORI A. , WILKOFF BRUCE , SIMMONS TONY , MORANT VICTOR , CASTLE LON W.
Published: July 2006

Recent reports have shown poor survival of some leads currently in use. Long‐term survival analysis of 2,444 leads (1,059 atrial and 1,385 ventricular) implanted in this institution since January 1980, and having at least 1 month of follow‐up was performed. The survival of 123 different models was compared with the average survival of all the leads implanted in the corresponding chamber. Failure was defined as inactivation of the lead (electrical abandonment, explant, or cap) due to insulator and/or conductor fracture. Results: The mean follow‐up was 33 ± 32 months. The cumulative survival for different atrial lead models was consistent with the average performance in the atrium. No atrial lead showed better or worse survival compared to the others. In the ventricular group, the Medtronic 4012 lead showed statistically significant poorer survival (P = 0.01) compared with the average survival of the ventricular leads. The Cardiac Pacemakers, Inc. (CPI) 4010 lead showed a nonsignificant (P = 0.12) worse performance than the average for ventricular leads. Conclusions: (1) The Medtronic 4012 had a significantly poorer performance than the rest of the leads. A trend in similar direction was found for the CPI 4010, also in the ventricular group; (2) Atrial lead models showed a stable survival; and (3) Frequent follow‐up is required for some leads, especially in pacemaker dependent patients.
The Measurement of the Paced Depolarization Integral Using the Braided Endocardial Lead
Authors: LU RICHARD M.T. , DAWSON ALBERT K.
Published: July 2006

Previous studies have shown that the paced depolarization integral (PDI) data recorded in unipolar configuration could potentially improve the specificity of tachyarrhythmia classification in an implantable cardioverter defibrillator (ICD). However, the defibrillation protection would be compromised if the ICD case were used as an indifferent electrode. Since transvenous defibrillation leads are being investigated to be used with ICDs, this study determined if reliable PDI data could be obtained using the braided endocardial defibrillation lead (BEDL), The results demonstrated that comparable PDI values and PDI changes with epinephrine induced sinus tachycardia were obtained with all three tested sensing configurations: conventional unipolar, tip electrode to right ventricular defibrillation electrode, and tip electrode to superior vena cava defibrillation electrode. Therefore, the BEDL can be used to measure PDI data, which possibly may improve tachyarrhythmia classification in an ICD, without compromising its defibrillation protection.
In Vitro Evaluation of New Design Lead Anchoring Sleeves
Authors: LI HONG , HELLAND JOHN
Published: July 2006

The purpose of this study was to evaluate various new lead anchoring sleeve designs. These designs were intended to allow coaxial bipolar leads to be tied down and remain securely in position with minimal damage to the lead body, whether tied down with moderate or high tie forces. Axial grooves were made on the outer and/or inner walls of various anchoring sleeve designs. Anchoring sleeves made of extra tear resistant (ETR) platinum catalyzed and peroxide catalyzed (MDX) silicone rubber of various shore, hardnesses were tested on various Siemens Pacesetter (S‐P) and other manufacturers' lead bodies. Tests to slide the sleeves were conducted with the leads in dry and wet conditions, and with and without the Fast‐Pass(tm) (Siemens Pacesetter, Inc.) coating for Iubriciousness. Tie‐down deformation of coils was measured from x‐ray photos. Mechanical tests and stress calculations were also done to evaluate the mechanical properties of the different lead bodies being tested. The test results showed that compared with existing sleeves, the new design MDX sleeves with axial grooves on the outer wall of the anchoring sleeves provided much lower resultant deformation (62%‐84%) on leads when tied down tightly, and exhibited similar sliding forces. Also, it was determined that the MDX anchoring sleeves provided much improved slip forces of two to three times higher than the ETR sleeves. Tie‐down damage can also be significantly reduced by strengthening lead bodies. With the protection of the new sleeves, the tie‐down damage of S‐P leads was the lowest among all the manufacturers' polyurethane or silicone leads tested. The new designs studied also resulted in a hierarchy of choices for use in pacemaker leads.
Septal His‐Purkinje Ventricular Pacing in Canines: A New Endocardial Electrode Approach
Authors: KARPAWICH PETER P. , GATES JAMES , STOKES KENNETH B.
Published: July 2006

Ventricular activation sequences and cardiac performance are influenced by pacing sites. Stimulation of or close to the specialized a trioventricular (AV) conduction system optimizes paced ventricular function compared to alternative epi‐ or endocardial muscle conduction sites. This study reports a new endocardial electrode implant approach to approximate septal His‐Purkinje ventricular pacing. Five 6‐month‐old beagles were used, A custom, platinum‐iridium, exposed helical screw electrode (Medtronic, Inc.), 4.5‐mm long, with a 17.8‐mm2 surface area, was designed with a polyurethane covered 4 filar MP35N nickle conductor lead. An 8 French sheath (USCI, Inc.) was modified as introducer to permit simultaneous implant intracardiac pressure and electrogram recordings. Following a thoracotomy, the introducer was inserted through the right atrial appendage and advanced to record optimal His‐bundle electrogram while maintaining atrial pressure along the septal tricuspid valve annulus. After electrode implant, ECG demonstrated narrow paced QRS morphology. Mean implant values showed sensed R wave 6,3 mV, slew rate 0.65 V/sec, pacing impedance 319 ohms, and threshold 0.9 V/3.3 mA at 0.5‐msec output. Necropsy showed implant above the tricuspid annulus with electrode extension into and contained within the proximal ventricular septum. This study demonstrates that an endocardial septal approach to His‐Purkinje ventricular pacing to optimize paced ventricular function is feasible with a new electrode design and precise septal implant technique. Alternative introducer designs may permit tranvenous application of this approach.
Interaction Between Permanent Cardiac Pacing and Electrocautery: The Significance of Electrode Position
Authors: CHAUVIN MICHEL , CRENNER FRANCIS , BRECHENMACHER CLAUDE
Published: July 2006

The danger in utilizing electrocautery during a surgical procedure on a pacemaker patient depends, to a great extent, on the position of the electrodes. We have studied this influence in an experimental model consisting of a plexiglass tank filled with a saline solution. Seven pacemakers were successively attached to an immersed and fixed frame and connected to a lead whose tip remains in the same location throughout the experiments. An ERBOTOM T 400 C generator (450 KHz) was used in an unmodulated unipolar mode at a maximum output (400 W). The high frequency current was delivered between a patch located successively at six preset positions in the tank and another electrode applied to 176 surface locations. For each position, we measured the currents in the lead with a separate measurement circuit connected in parallel on the same lead. Results were displayed on a map. Regardless of the patch position, currents were: (1) at a maximum when high frequency was delivered close to the pacemakers and around the tip of the lead; (2) negligible when applied to the path followed by the lead; and (3) a function of the distance between electrodes. These results may help to formulate recommendations to prevent accidents when using electrocautery in pacemaker patients.
The Lithium/Iodine Battery: A Historical Perspective
Authors: GREATBATCH WILSON , HOLMES CURTIS F.
Published: July 2006

The lithium/iodine‐polyvinylpyridine battery, first implanted 20 years ago, has become the power source of choice for the cardiac pacemaker. Over the last 20 years, improvements in cell chemistry, cell design, and modeling of cell performance have been made. Cells today exhibit an energy density over three times as great as cells produced in 1972. Well over 2 million pacemakers have been implanted with this chemistry, and the system has exhibited excellent reliability.
Incidence and Predictors of Loss of Pacing in the Atrium in Patients with Sick Sinus Syndrome
Authors: SGARBOSSA ELENA B. , PINSKI SERGIO L. , CASTLE LON W. , TROHMAN RICHARD G. , MALONEY JAMES D.
Published: July 2006

Atrial and dual‐chamber pacemakers may be associated with reduced morbidity in patients with the sick sinus syndrome (SSS). In some patients, however, subsequent development of chronic atrial fibrillation or atrial lead failure make long‐term pacing in the atrium not feasible. We analyzed the incidence and predictors of loss of atrial pacing in 395 consecutive patients with SSS (376 with dual‐chamber pacemakers and 19 with single‐chamber atrial pacemakers). None of them was in established atrial fibrillation at time of implant. Patients were followed‐up for 55 ± 35 months. Actuarial survival of effective atrial pacing was 92.5% at 1 year, 85% at 5 years, and 76.5% at 10 years. Overall, 60 patients lost atrial pacing. The most frequent cause was the development of chronic atrial fibrillation (53 patients). By multivariate analysis (Cox proportional‐hazards model), independent predictors of Joss of pacing in the atrium were preimplant episodes of paroxysmal atrial fibrillation (PAF) lasting more than 1 hour (P < 0.001; hazard ratio (HR) = 4.3); prior history of PAF for more than 5 years (P < 0.001; HR = 2.67; and endocardial P wave < 2 mV (P = 0.014; HR = 1.96). In a subgroup of patients (n = 187) who had echocardiograms, a left atrium > 50 mm was also an independent predictor of loss of atrial pacing (P = 0.028; HR = 2.28). Conclusions: 1) most patients with SSS can maintain long‐term atrial pacing; 2) loss of pacing in the atrium is related to the previous history of PAF, left atrial enlargement, and low amplitude of the endocardial P wave at implant; and 3) patients with these risks variables are less than ideal candidates for atrial pacing modes. In them, the implant of DDDR units might be indicated, to provide wide flexibility in case reprogramming to a ventricular pacing mode is required.
Long‐Term Intrinsic Pacemaker Function in Patients Paced for Sinus Node Deficiency After Cardiac Transplantation
Authors: HEINZ GOTTFRIED , KRATOCHWILL CHRISTOPH , BUXBAUM PETER , KREINER GERHARD , LAUFER GÜNTHER , GÖSSINGER HEINZ , LACZKOVICS AXEL
Published: July 2006

Fifteen cardiac transplant recipients requiring permanent pacing (AAJ, n = 9; VVI, n = 6; rate responsive devices, n = 11) for postoperative sinus node (SN) insufficiency underwent evaluation of long‐term SN function 240 to 1,461 days after transplantation. The intrinsic rhythm at the time of discharge was sinus in 7 patients; functional escape in 6 patients; and pacemaker dependent in 2 patients. At follow‐up, 5 patients had regained regular sinus rhythm, accounting for a total of 11 patients in sinus rhythm while 4 patients were in functional bradycardia. The SN recovery time as determined by the permanent pacemaker was normal (< 1,500 msec) in only 1/8 patients in whom it was determined, although 4 of these 8 patients were temporarily overriding the pacemaker during ambulatory monitoring. Patients with pathological SN recovery times included 3 patients with late return of sinus rhythm and 4 patients who had recovered normal sinus rhythm before their discharge from the hospital. Three patients developed late symptoms despite apparent early normalization and underwent delayed pacemaker implantations on postoperative days 35, 52, and 225, respectively. We conclude that, in patients requiring pacemaker implantation after cardiac transplantation, normalization of SN function cannot be inferred from just return of sinus rhythm, regardless of whether it occurs early or late. These findings may have implications when a pacemaker exchange or explanation is being considered.
Atrioventricular Conduction Disturbances in Patients with Sinoatrial Node Disease and Atrial Pacing
Authors: ŜWIĄTECKA GRAŻYNA , SIELSKI SŁAWOMIR , WILCZEK RAJMUND , JACKOWIAK DOROTA , KUBICA JACEK , RACZAK GRZEGORZ
Published: July 2006

In sinoatrial node disease (SND) atrial pacing may be limited by progression of AV block. The incidence of AV block after All systems implantation range, according to various authors, from 0% to 12%. The aim of this study was to examine the AV conduction disturbances that forced a change in the mode of pacing in patients with AAI pacemakers. The information was collected retrospectively from a cohort of 122 patients. The follow‐up period ranged from 5 to 83 months (mean = 35J. Among these patients there were 37 with sinus bradycardia and 85 with bradycardia‐tachycardia syndrome. Their mean age was 63 years. Before AAI pacemaker insertion, all patients had normal AV conduction on 12‐lead EGG, and all but five had a Wenckebach cycle length shorter than 500 msec. Seven out of these 122 patients (5.7%) developed symptomatic conduction disturbances (second‐degree type I AV block in five, second degree type II AV block in one, and third‐degree AV block in one], necessitating a change from AAI to another mode of pacing. We conclude that progression of AV block after atrial pacemaker implantation in patients with SND is infrequent and mild in the majority of cases. Intraventricular disturbances such as left anterior hemiblock represent contraindication to AAI pacing particularly in patients who may be in need of antiarrhythmic drugs.
Predictive Value of the P Wave at Implantation for Atrial Fibrillation After VVI Pacemaker Implantation
Authors: SNOECK J. , DECOSTER H. , VRINTS C. , MARCHAND X. , KAHN J.C. , VERHERSTRAETEN M. , BERKHOF M. , FRANQUE L.
Published: July 2006

This study assesses the value of P wave measurements on the surface EGG at implantation, in the prediction of atrial fibrillation in VVI paced patients. From a consecutive series of 320 pacemaker implantations 172 WI paced patients for symptomatic atrioventricular block (AVB) (n = 126; mean age 69 ± 14) or sick sinus syndrome (SSS) (n = 56; mean age 68,6 ± 12] and in sinus rhythm at implantation were used in this study. P wave duration in VI is correlated with the incidence of atrial fibrillation during 5 years of follow‐up. VI at implantation was significantly longer (114.6 ± 2.7 msec) in the patients who developed atrial fibrillation than in those who did not (91.9 ± 2.7 msec) (P < 0.001). Although positive predictive accuracy increases progressively for higher VI values for AVB and SSS, the negative predictive and diagnostic accuracy of V1 criteria were Jess in SSS. Application of the Bayes' theorem showed that in SSS the probability to develop atrial fibrillation is 33% for V1 < 110 msec and is for V1 < 90 msec still higher than that reported in DDD paced patients. In the AVB group the probability to develop atrial fibrillation is 8% for V1 < 110 msec and 6% for V1 < 100 msec. It seems, therefore, that atrial stimulation (AAI or DDD) is always indicated in SSS. In AVB with V1 < 100 msec, DDD pacing, if not needed for other indications, apparently does not offer much benefit in the prophylaxis of atrial fibrillation.
Reverse Use Dependence of Antiarrhythmic Class la, Ib, and Ic: Effects of Drugs on the Action Potential Duration?
Authors: LANGENFELD HEINER , KÖHLER CHRISTIANE , WEIRICH JÖRG , KIRSTEIN MICHAEL , KOCHSIEK KURT
Published: July 2006

The prolongation of the action potential duration (APD) induced by sotalol has been shown to be diminished with increasing heart rate. This phenomenon is called “reverse use dependence.” We examined the la, Ib, and Ic effects of different Class I drugs on the APD under normal and fast stimulation rates (1.0 and 2.5 Hz) in isolated rabbit atria) and ventricular muscles by means of intracelular microelectrodes. Results (n = 98): With 1.0 Hz lidocaine fib, 4.3 ? 10−5 M) shortened the APD at 90% repolarization (APD90) in the atrium by 9% and in the ventricle lay 8% (NS), whereas quinidine (la, 2.2 ? 10 −5 M) and prajmaline (la, 10 −6 M) prolonged the APD90 in the atrium (quinidine +45%; prajmaline +10%, P < 0.001) and in the ventricle (+ 42%, P < 0.001; +17%, P < 0.05J. Propafenone (Ic, 2.6 ? 10 −6 M) showed this effect only in the atrium (APD90 + 33%; P < 0.01). With the faster stimulation rate of 2.5 Hz we could not find a significant influence of any drug on the APD90 in the ventricle and only quinidine prolonged the APD90 in the atrium by 16% (P < 0.05). Conclusions: The subclassification of Class I antiarrhythmic drugs that is based on APD modifying influences is only valid under normal heart rates (1.0 Hz). During tachycardia these actions are absent and the phenomenon of “reverse use dependence” is found in Class I drugs. Therefore, an additional antiarrhythmic effect due to APD modification by the examined drugs should not be expected at rapid heart rates.
Frequency Dependent Effects of d‐Sotalol and Amiodarone on the Action Potential Duration of the Human Right Ventricle
Authors: HUIKURI HEIKKI V. , YLI‐MÄYRY SINIKKA
Published: July 2006

Frequency dependent effects of d‐Sotalol (2.0 mg/kg IV, n = 6) and amiodarone (400 mg/day for 3 months, n = 9) were studied on the action potential duration (APD) in 14 patients who underwent electrophysiological testing. Monophasic action potentials were recorded from the right ventricle at five different steady‐state paced cycle lengths (700 msec, 600 msec, 500 msec, 400 msec, and 350 msec), and during ventricular extra stimuli with coupling intervals between 300 msec and 1000 msec, before and after d‐sotalol and amiodarone, respectively. D‐sotalol caused a prolongation of the APD at slow steady‐state stimulation rates (11 ± 5% at cycle length of 700 msec), which became attenuated at faster cycle lengths (5 ± 3% at cycle length of 350 msec). Prolongation of APD after amiodarone was independent of pacing rate, e.g., 12 ± 9% at cycle length of 700 msec, and 11 ± 6% at cycle length of 350 msec. Similar frequency dependent prolongation of the APD was observed during abrupt changes of cycle lengths after d‐sotalol, whereas amiodarone caused uniform prolongation of the APD at different extrasfimulus intervals. Thus, d‐sotalol, a nonselective potassium channel blacker, has reverse use‐dependent effects on the human ventricular APD, while amiodarone with greater potassium channel selectivity, has equal ability to prolong the ventricular APD at fast and slow heart rates.
Atrial Fibrillation in Wolff‐Parkinson‐White Syndrome: Reversal of Isoproterenol Effects by Sotalol
Authors: MADRID A.H. , MORO C. , HUERTA E. MARÍN , NOVO L. , MESTRE J.L.
Published: July 2006

Sotalol has Class II and III antiarrhythmic effects. Its efficacy and safety as a treatment of atrial fibrillation in patients with the Wolff‐Parkinson‐White (WPW) syndrome is controversial. We evaluated the effects of isoproterenol and IV sotalol (1.5 mg/kg in 10 minutes) given together versus isoproterenol alone on anterograde conduction through the AV node and accessory pathway. Atrial fibrillation was induced in 22 patients with WPW (13 men, 9 women, 36 ± 16 years old). AV node and accessory pathway conduction were both enhanced by isoproterenol, although the effect was greater on the AV node. The minimum interval between preexcited QRS complexes shortened in all patients. Conversely, sotalol caused a significant prolongation of the shortest preexcited QRS interval as well as of the shortest interval between narrow QRS complexes. In addition, sotalol reversed all the effects of isoproterenol during atrial fibrillation. The percent of preexcited QRS complexes was not significantly modified because variations in ventricular preexcitation results from a balance between the relative effects on refractoriness of the accessory pathway versus of the AV node and in the amount of respective anterograde and‐ retrograde concealed conduction. There were no serious adverse effects.’Reversion to sinus rhythm was documented in 12 patients (60%). These short‐term observations suggest that sotalol may be safe and effective in the treatment of patients with WPW and atrial fibrillation.
Prediction of Antiarrhythmic Efficacy of Class I and III Agents in Patients with Ventricular Tachycardia by Signal‐Averaged ECG Analysis
Authors: KULAKOWSKI PIOTR , BASHIR YAVER , HEALD SPENCER , PAUL VINCE , ANDERSON MARK H. , GIBSON SHEILA , MALIK MAREK , CAMM A. JOHN
Published: July 2006

The effects of procainamide and dofetilide (pure Class III antiarrhythmic agent) on the signal‐averaged ECG (SAECG) were examined in relation to the results of programmed ventricular stimulation studies in 25 patients with inducible sustained monomorphic ventricular tachycardia. Procainamide prolonged significantly the total QRS and low amplitude signal durations (140 ± 31 msec vs 166 ± 48 msec, P < 0.0001; 50 ± 25 msec vs 65 ± 38 msec, P < 0.002, respectively) whereas the root mean square voltage of the last 40 msec of the QRS complex was significantly reduced (22 ± 21 (iV vs 13 ± 12 p‐V, P < 0,006). Procainamide was effective (prevention of the inducibility of sustained ventricular tachycardia or prolongation of the cycle length of ventricular tachycardia by > 100 msec) in 15 of 27 drug trials. Of the procainamide induced SAECG changes, the fractional prolongation of the total QRS duration was the best parameter that identified effectively treated patients (24%± 16% in responders vs 10%± 11% in nonresponders, P < 0.014). Afractional prolongation of the total QRS duration by > 15% identified effectively treated patients with a sensitivity of 87%, specificity of 81%, and an overall predictive accuracy of 84%. Dofetilide did not change the SAECG, and no SAECG parameter predicted the results of programmed ventricular stimulation. The effects of both drugs on the spectral analysis (area ratios) and on the spectral temporal mapping (the values of normality factor) of the SAECG were not consistent. In conclusion, antiarrhythmic efficacy of procainamide can be predicted by the degree of drug induced prolongation of the signal‐averaged QRS complex. Dofetilide does not significantly affect the SAECG, and its efficacy cannot be predicted by the SAECG analysis.
Acute and Chronic Electrophysiological Effects of Pentisomide on the Sinus and AV Nodal Function, Noninvasive Evaluation by a Pacemaker with Temporary Pacing Inhibition
Authors: ADORNATO ENRICO , PENNISI VIRGILIO , CATANZARITI DOMENICO , PANGALLO ANTONIO
Published: July 2006

The acute and chronic electrophysiological effects on sinus function and AV nodal conduction of pentisomide (Pen), a new antiarrhythmic agent, were studied in ten patients with sick sinus syndrome (SSS) (group I) and in ten patients with normal sinus function (group II) using a permanent pacemaker with temporary pacing inhibition (Symbios 7005 Medtronic, Inc.). We measured noninvasively the corrected sinus node recovery time (CSNRT), the sino‐atrial conduction time (SACT), according to Narula's method and the Wenckebach point before and after Pen administration, acutely and orally for 10 days. In group I intravenous injection (4 mg/kg) and oral administration (450 mg bid) of Pen significantly prolonged the CSNRT (+ 217% and + 149%, respectively) and the SACT (+ 63% and + 49%, respectively). In group II only the intravenous injection of Pen provoked a significant modification of CSNRT (+ 12%) and SACT (+ 14%). No modification in AV nodal conduction was noted in any patient. These results suggest that Pen must be used with caution in patients with sinus nodal dysfunction.
Mexiletine and Propafenone: A Comparative Study of Monotherapy, Low, and Full Dose Combination Therapy
Authors: TAKANAKA CHIEI , NONOKAWA MAKOTO , MACHII TAKESHI , LEE SHOKOKU , KATO HIDEKI , HARUNA MASATO , YABE SEITARO
Published: July 2006

The electrophysiological effects of combination therapy of mexiletine and propafenone were assessed using standard 12‐Iead electrocardiogram (standard ECG), signal‐averaged EGG (SAECG), and ambulatory ECG in 31 patients with ventricular arrhythmias. All patients underwent mexiletine monotherapy (M‐mono), propafenone monotherapy (P‐mono), low dose combination therapy (low M 4‐ P), and full dose combination therapy (full M + P). Full M + P increased the PQ interval and QRS duration to the same extent as P‐mono did. Low M + P increased PQ interval and QRS duration to a lesser extent than P‐mono and full M + P did. P‐mono and full M + P significantly decreased root mean square (RMS) and increased f‐QRS in SAECG, while M‐mono and low M + P showed only a weak trend. SAECGs with late potentials increased in number with treatments; 9 in predrug control, 11 on M‐mono, 15 on P‐mono, 10 on low M + P, and 14 on full M + P. The percent suppression of frequent premature ventricular contractions (PVCs) (> 1,000/day) with M‐mono, P‐mono, low M + P, and full M + P were 46.4 ± 9.0,56.6 ± 10.4,64.4 ± 9.2, and 71.4 ± 7.1, respectively, and those of frequent couplets (> 10/day) were 58.3 ± 17.7, 62.6 ± 23.6, 87.5 ± 6.2, and 92.1 ± 4.0, respectively. Thus, full dose combination of mexiletine and propafenone exhibited the maximum antiarrhythmic efficacy without enhancement of effects on standard ECG and SAECG. Low dose combination therapy showed better antiarrhythmic efficacy in association with lesser effects on standard ECG and SAECG compared with propafenone monotherapy.
Separation of Ventricular Tachycardia From Sinus Rhythm Using a Practical, Real‐Time Template Matching Computer System
Authors: GREENHUT SAUL E. , DEERING THOMAS F. , STEINHAUS BRUCE M. , INGRAM JO L. , CAMP STEVEN R. , DiCARLO LORENZO A.
Published: July 2006

Template matching morphology analysis of the infra‐ventricular electrogram (IVEG) has been proposed for inclusion in implantable cardioverter defibrillators (ICDs) to reduce the number of false ventricular tachyarrhythmia detections caused by rate overlap between ventricular tachycardia (VT) and sinus tachycardia and for supraventricular tachycardia. Template matching techniques have been developed that reduce the computational complexity while preserving the perceived important aspects of electrogram amplitude and baseline independence found in such computationally unsolved methods as correlation waveform analysis (CWA). These methods have been shown to work as well as CWA for separation of VT, however, they have not been proven in real‐time on a system that incorporates many of the constraints of present day ICDs. The present study was undertaken with two purposes: (1) to determine if real‐time IVEG template matching analysis on an ICD sensing emulator was accurate in separating VT from sinus rhythm (SR) electrograms; and (2) to compare amplitude normalized area of difference (NAD) with signature analysis (SIG), a new, computationally less expensive technique that normalizes for amplitude variation within the expected physiological level of variability. In this study, JVEGs, obtained from 16 patients who underwent electrophysiological study (EPS) for evaluation of sustained ventricular arrhythmia, were digitized to 250 Hz with 6‐bit quantization after filtering (16‐44 Hz) and differentiation. After an SR template was selected and periodically updated, it was compared to subsequent IVEGs using NAD and SIG. In general, SIG calculates the fraction of samples occurring outside template window boundaries. Eleven‐beat running medians from beat‐by‐beat NAD and SIG results were determined. The maximum median during VT was subtracted from the minimum median during SR with the result equal to the separation margin. With the minimum separation threshold set to 0 (i.e., no overlap), 0.1, and 0.2, NAD separated 16/16, 14/16, and 9/16 VTs, while SIG separated 15/16, 14/16, and 13/16 VTs, respectively. While NAD separated more VT episodes on the strict basis of no overlap, SIG separated more than NAD as the safety margin was further increased. Conclusions: (1) template matching morphology techniques can potentially be implemented in ICDs; (2) using a patient specific threshold, NAD and SIG appear capable of separating VTfrom SR in most patients; and (3) SIG and NAD appear to be similar in accuracy. Thus, SIG may be preferable since it significantly reduces the computational load.
Ventricular Tachycardia Detection Using Bipolar Electrogram Analysis is Site Specific
Authors: DiCarlo LORENZO A. , JENKINS JANICE M. , CHIANG CHIH‐MING J. , WINSTON STUART A. , SILKA MICHAEL J. , MATNEY KATHY
Published: July 2006

While algorithms for bipolar intraventricular electrogram analysis have potential use in complementing rate criteria for ventricular tachycardia (VT) detection by implantable antitachycardia devices, the sensitivity of such algorithms to the intracavitary site of electrogram detection has not been determined. In this study, unfiltered (1‐500 Hz) electrograms were recorded from a bipolar electrode catheter initially positioned at the right ventricular (RV) apex (site 1) of 12 patients during sinus rhythm (SRI) and during induced monomorphic VT (VTI). Sinus rhythm (SR2) and the identical VT (VT2) were recorded a second time after repositioning the same electrode catheter within the RV apex (site 2) 7‐44 mm (mean ± SD = 15 ± W) from its original site. The data were digitized at 1,000 Hz. Templates from SRI and SR2, respectively, were compared subsequently with individual intraventricular electrograms from 15‐25 sec passages of SRI and VTI and SR2 and VT2, respectively, using correlation waveform analysis. At site 1, the mean patient correlation coefficient ranged from 0.982‐0.998 during SRI and 0.062‐0.975 during VTI. At site 2, the mean patient correlation coefficient ranged from 0.995‐0.998 during SR2 and 0.113‐0.983 during VT2. Using a correlation threshold of 0.9, VT was differentiated from SR in 11/12 patients (91%) overall: 8/12 patients (67%) at site 1, 9/12 patients (75%) at site 2, and 6/12 patients (50%) at both sites. Thus, while discrimination of VT from SR is feasible with morphological analysis of bipolar right ventricular intracavitary electrograms, the accuracy of bipolar intraventricular electrogram analysis may depend upon intracavitary electrode location in selected patients.
Role of Early Afterdepolarization in Familial Long QTU Syndrome and Torsade de Pointes
Authors: ZHOU JIN‐TAI , ZHENG LIANG‐RONG , LIU WEI‐YU
Published: July 2006

Torsade de pointes (TdP) syncopal episodes were almost invariably precipitated by emotional stress or menstruation in a 17‐year‐old girl. V wave accentuation occurred during sinus rhythm without pauses in periods of heightened sympathetic tone. To examine the role of early afterdepolarization (EAD), monophasic action potentials were recorded during ventricular extrasystoles and TdP occurring spontaneously and induced by ventricular pacing. The effects of lidocaine, verapamil, propranolol, and epinephrine were assessed. Our data show that: (1) EAD plays a significant role in the genesis of familial long QTU syndrome and TdP; (2) rapid ventricular pacing causes postpause‐dependent EADs, U waves, and TdP; and (3) EAD is enhanced by epinephrine infusion in the absence of pause, whereas EAD‐triggered firing is inhibited by verapamil and propranolol but not by lidocaine.
Survival After A First Episode of Ventricular Tachycardia or Fibrillation
Authors: PINSKI SERGIO L. , MALONEY JAMES D. , SGARBOSSA ELENA B. , JUBRAN FUAD , TROHMAN RICHARD G.
Published: July 2006

Recent outcome analyses in ventricular tachycardia (VT) and ventricular fibrillation (VF) have included patients undergoing electrophysiological study (EPS) at tertiary care centers. The selection process involved could introduce bias in the reported populations. We analyzed the outcome of 42 consecutive patients (aged 63 ± 11 years) admitted to a coronary care unit within 48 hours of a first episode of VT/VF not associated with reversible causes. All patients recovered neurologically and were candidates for EPS. Nine patients (21%) died during the initial hospitalization (none had EPS), and another nine died during a follow‐up of 17 ± 12 months. Actuarial survival at 1 and 2 years was 64% and 62%, respectively. By Cox's model, congestive heart failure functional Class III‐IV (P = 0.008; hazard ratio = 3.7) was the only independent prognostic factor. Among patients discharged, subsequent survival did not depend on the performance of EPS or on the antiarrhythmic therapeutic modalities used. Mortality after a first episode of VT/VF is high. Severe congestive heart failure is the most powerful prognostic factor. Studies including successfully referred patients undergoing EPS may not reflect the true natural history of patients with VT/VF.