bluuebunny/crossref_metadata_2025 huggingface dataset:
Acute Atrial Endocardial P Wave Amplitude and Chronic Pacemaker Sensitivity Requirements: Relation to Patient Age and Presence of Sinus Node Disease
Authors: BRANDT JOHAN , ATTEWELL ROBYN , FÅHRAEUS THOMAS , SCHÜLLER HANS
Published: July 2006

Data are reviewed from 88 patients who received double, passive‐fixation unipolar endocardial leads for DDD pacemaker treatment. Identical electrodes were used in the right atrium and the right ventricle. Intra‐atrial P wave amplitudes, intraventricular QRS complex amplitudes, and atrial and ventricular pacing thresholds were determined at implantation. The intra‐atrial P wave amplitudes were not significantly correlated to the intraventricular QRS complex amplitudes. No significant correlation was found between the atrial stimulation thresholds and the ventricular pacing thresholds. The intra‐atrial P wave amplitude showed a significant inverse and logarithmic correlation with patient age (P = 0.007). Furthermore, patients with sinus node disease had significantly lower infra‐atrial P wave amplitudes (P = 0.04) than patients without this abnormality. The acute atrial and ventricular pacing thresholds and the intraventricular QRS complex amplitude were not correlated to patient age or presence of sinus node disease. Patients requiring higher atrial amplifier sensitivity settings during follow‐up were significantly older (P < 0.05) than those in whom lower atrial sensitivities were sufficient. A postoperative attenuation of the atrial electrogram was detectable by sensitivity programming procedures in 29 of the patients (35%). This phenomenon did not significantly relate to patient age or presence of sinus node disease. No case of permanent atrial undersensing occurred. It is suggested that the lower intra‐atrial P wave amplitudes in older patients and patients with sinus node disease reflect degenerative changes in the atrial myocardium. The statistical relations found appear to motivate special attention to atrial sensing in these patient groups.
The Defibrillation Success Rate Versus Energy Relationship: Part II—Estimation with the “Bootstrap”
Authors: GLINER BRADFORD E. , MURAKAWA YUJI , THAKOR NITISH V.
Published: July 2006

Seventy or so defibrillation trials were typically attempted to determine the relationship between defibrillation success rate and energy (DSRE). Clinically, it may be desirable to estimate the DSRE relationship with fewer trials. We used the statistical resampling technique called the “bootstrap” to determine the number of defibrillation trials necessary for an accurate estimation of the DSRE relationship. The bootstrap technique assumes that the observed database is the maximum likelihood sample of the estimated population. The observed database is repeatedly resampled to produce a large bootstrap database and the bootstrap best estimate of a statistic is determined. DSRE data were obtained from ten dogs (20.5 ± 3.5 kg). We bootstrapped our experimental DSRE data by two methods: (1) randomly choosing with replacement a specified number of defibrillation trials per energy; and (2) randomly choosing with replacement a specified number of defibrillation trials per bootstrap replication. For both bootstrap techniques, 100 replications were made. We performed a linear regression analysis on the bootstrap success rates and the observed success rates determined from 71.0 ± 6.8 defibrillation attempts from each of the ten dogs. We concluded that 28 defibrillation trials are necessary to estimate the observed DSRE relationship with a correlation coefficient of 0.95.
Electrophysiological and Anatomical Substrates for Late Potential Recorded by Signal Averaging in Seven‐Day‐Old Myocardial Infarction in Dogs
Authors: YOH SHISEI , OGAWA SATOSHI , SATOH YOSHIHIRO , FURUNO IZUMI , SAEKI KIMIKO , SADANAGA TUNEAKI , NAKAMURA YOSHIRO
Published: July 2006

A filtered QRS (fQRS) was recorded by signal averaging in 7‐day‐oJd myocardial infarction (MI) in dogs to detect late potential (LP). The criteria for the LP included a duration of fQRS (D) ≥ 60 msec and a voltage in the last 15 msec (VI5) ≤ 10 μV. These parameters were determined from the control data from 15 dogs without infarction (D: 45 to 60 msec and V15: 12.0 to 83.6 μV). On the seventh day of infarction, the D had increased from 53.5 ± 4.7 to 62.2 ± 9.6 msec (P < 0.05) and the V15 decreased from 38.6 ± 19.5 to 18.4 ± 16.0 μV (P < 0.01). Of 23 dogs, 14 met the LP criteria (group A) and 9 did not (group B). Sustained ventricular tachycardia (SVT) was induced in 12 group A dogs and in none of the group B dogs. The delayed epicardial activation (DEA) was recorded after the end of QRS at 5.1 ± 4.7 sites in group A dogs and 1.3 ± 1.8 sites in group B dogs (P < 0.05). The maximum value of epicardial activation time was more prolonged in group A than in group B (70.0 ± 28.3 vs 44.4 ± 9.8 msec, P < 0.01). The area of MI was more extensive in dogs with DEA than those without (24.9 ± 5.8% vs 10.3 ± 9.0% of the total left ventricular weight, P < 0.01). In 72 of 90 sites with DEA, the thickness of the surviving epicardial muscle was ≤1 mm. The sensitivity and specificity of the criteria for LP in detecting DEA were 71.4% and 55.6%, and 100% and 81.8% for predicting inducibility of SVT. It was thus concluded that LP, reflected the DEA, was identified from infarct areas of slow conduction within a reentry circuit of SVT.
Ventricular Fibrillation Following Elective Cardioversion in a Patient with Permanent Pacemaker
Authors: VERA ZAKAUDDIN , BOMMER WILLIAM J. , DESAI JAWAHAR M.
Published: July 2006

Elective cardioversion was undertaken in a patient with a VVI pacemaker and atrial tachyarrhythmia after converting the pacemaker to a VOO mode of function. The cardioverter output energy was unwittingly synchronized to the pacemaker output pulses that were falling randomly in various portions of the cardiac cycle. This resulted in the cardioverter DC shock being discharged in the ST segment of (he native QRS with consequent ventricular fibrillation.
Management of Spinal Cord Stimulators in Patients with Cardiac Pacemakers
Authors: ANDERSEN CLAUS , OXHØJ HENRIK , ARNSBO PER
Published: July 2006

We report a case of spinal cord stimulation (neurostimularion) as treatment for angina pectoris pain in a patient with a demand pacemaker. The precautions to avoid inhibition of the demand pacemaker by the neurostimulator are discussed.
Long‐Term Comparison of the Electrical Characteristics of Polyurethane and Polyethylene Insulated Ventricular Leads
Authors: BLUHM GÖSTA , LARSEN FLEMMING F. , NORDLANDER ROLF , PEHRSSON S. KENNETH
Published: July 2006

Two types of pacing leads with different insulation material, polyurethane, and polyethylene, were followed for 44 months with respect to their electrophysiological characteristics and complications. In 48 patients, 32 polyurethane leads (Lifeline 493–03) and 16 polyethylene leads (EMT 588 D) were implanted and connected in all cases to the same type of programmable ventricular inhibited (VVI) pulse generator (Programalith, Pacesetter). There was a significant fall during the follow‐up in lead impedance with the polyurethane leads (495 ± 62 to 444 ± 58 ohms, P < 0.01), whereas the corresponding measurements for the polyethylene leads were essentially unchanged (360 ± 58 to 378 ± 71 ohm, ns). The energy of the stimulation threshold tended to increase in the polyurethane group, whereas an opposite tendency was observed in the polyethylene group. Pacing and/or lead failures were not observed in any case. The observed fall in impedance with the polyurethane leads was seemingly of no clinical significance.
The Effect of External Cardiac Pacing on Stroke Volume
Authors: TALIT UZI , LEACH CHARLES N. , WERNER MORGAN S. , SCHULMAN PETER
Published: July 2006

To evaluate the hemodynamic effects of external cardiac pacing, ten subjects with normal left ventricular function were paced at rates approximating their resting heart rates using an external pacemaker while continuous‐wave Doppler measurements from the aortic outflow were recorded. The Doppler flow velocity integral was used as an index of stroke volume and the product of heart rate and flow velocity integral was used as an index of cardiac output. At a pacing rate 13% faster (range ‐5% to 32%) than the rate during sinus rhythm, the mean index of stroke volume was reduced 24% from 17.7 cm to 13,5 cm (P < 0.0002). However, the faster rate during external pacing partially compensated for the reduced stroke volume resulting in an index of cardiac output that was 14% lower compared to the prepaced index (1,297 vs 1,121 cm [P < 0.02]). Thus, in subjects with normal LV function, external pacing results in a small drop in cardiac output that may be partially overcome by increasing the pacing rate.
Atrial Pacing: Who do We Pace and What do We Expect? Experiences with 100 Atrial Pacemakers
Authors: KOLETTIS THEOFILOS M. , MILLER HUGH C. , BOON NICHOLAS A.
Published: July 2006

The records of 100 patients with permanent atrial pacemakers implanted over a 7‐year period were reviewed to assess the role and results of this mode of pacing. Indications for pacing were sick sinus syndrome in 91, carotid sinus hypersensitivity in 3, and use of an antitachycardia device in 6 patients. The mean follow‐up period was 32.9 months. Symptomatic relief was good. Lead dislodgment occurred in 11 patients (usually in the first week). Threshold rises not amenable to reprogramming occurred in three patients and loss of sensing occurred in seven patients but only one required intervention. Overall, 21 patients required reoperation. The type of lead did not influence the need for reoperation that appeared to be related to the experience of the operator. Complete atrioventricular block occurred in three patients, two of whom had carotid sinus hypersensitivity and one had sick sinus syndrome. Chronic atrial fibrillation occurred in five patients, none of whom required revision of the pacemaker system. Atrial pacing is a satisfactory pacing mode in patients with sick sinus syndrome. Provided satisfactory atrioventricular conduction has been shown by incremental atrial pacing to at least 120 beats/min and carotid hypersensitivity is absent, progression to complete atrioventricular block is uncommon. Greater implanting skills are required for good results.
Comparison of Low Rate Dual Chamber Pacing to Activity Responsive Rate Variable Ventricular Pacing
Authors: BATEY ROBERT L. , SWEESY MARK W. , SCALA GERALD , FORNEY RICHARD C.
Published: July 2006

A study was undertaken to evaluate exercise performance in 18 dual chamber pacemaker patients believed to be chronotropically incompetent. All patients were paced in a DDD AV synchronous mode of 80 beats per minute (beats/mm) as well as an externally triggered, activity responsive VVIR mode. Patients underwent two single blind, randomized symptom‐limited treadmill tests (Sheffield protocol). Four of the 18 patients achieved intrinsic rates > 100 beats/min and were deleted from the primary study. If was noted that all four of these patients performed best with intrinsic rate response and AV synchrony. Thirteen of the remaining 14 patients demonstrated improved exercise tolerance in the WIR mode. Average exercise time in the WIR mode (7:25 ± 3:12 min) was significantly greater (P < 0.05) than the DDD mode (6:01 ± 2:27 min). Work performed was significantly greater (P < 0.05) in the VVIR mode (4.77 ± 1.97 METS) than in the DDD mode (3.78 ± 0.77 METS). Maximum heart rates were 83.86 ± 5.11 beats/min in DDD mode versus 116.00 ± 30.56 beats/min in VVIR mode. The results demonstrated that improved exercise tolerance can be achieved with single chamber rate variable pacing compared to DDD pacing in patients with chronotropic incompetence. However, potential symptoms associated with loss of AV synchrony should be ruled out.
Thermally Controlled Laser Irradiation of the Myocardium with Intraoperative Ultrasound Monitoring
Authors: WATANABE GO , MUKAI AYUMU , MISAKI TAKURO , TSUBOTA MAKOTO , IWA TAKASHI
Published: July 2006

We used intraoperative ultrasonography (IOUS) to study the feasibility and safety of Nd:YAG laser irradiation of the myocardium in 26 canine left ventricular segments. During the laser irradiation process, the myocardial temperature was monitored and surface cooling was used. Afterward, intraoperative ultrasonographic scans, which enabled the evaluation of the irradiated lesions, were compared with cross sections made through the tissues. The total dose of laser energy ranged from 200 to 3,600 joules, and the estimated volume of irradiated lesions ranged from 76.8 to 2590 mm3. There were significant correlations between the laser discharge output (in joules [J]) and the irradiated lesion volume (P < 0.001), and between the laser energy density fin J/mm2) and the depth of the lesions (P < 0.01). Macroscopic examination of the cross sections of irradiated myocardium revealed that the lesions were well‐demarcated, but not charred or perforated. Thus, we could obtain a satisfactorily large zone of laser photocoagulation without inducing tissue damage, if surface cooling was used and the myocardial temperature was monitored. IOUS was successful in visualizing and locating the irradiated lesions that were seen as hypoechoic, clearly outlined nodules. We submit that this study has established the technical feasibility and dose‐response relationship of thermally controlled laser irradiation, and has demonstrated the usefulness of IOUS for the precise localization and monitoring of such laser treatment.
Unusual Cause of Dysuria: Migration of a Pacemaker Generator into the Urinary Bladder
Authors: BAUMGARTNER G. , NESSER H.J. , JURKOVIC K.
Published: July 2006

Following pacemaker implantation, a 71‐year‐old female developed infection of the generator pocket. Five years after relocation posterior to the rectus muscle she suffered from cystitis. Cystoscopy revealed the pacemaker generator to be lying within the urinary bladder. Healing was achieved by removing the pacemaker and reutilizing it, after sterilization, in a new pectoral pocket.
Complications after Single versus Dual Chamber Pacemaker Implantation
Authors: MUELLER XAVIER , SADEGHI HOSSEIN , KAPPENBERGER LUKAS
Published: July 2006

To compare the complication rate in patients having a dual chamber versus a single chamber pacing system, 337 consecutive procedures performed during a 3‐year period were analyzed prospectively. Two hundred fifty‐eight patients (77%) received a VVI pacemaker and 75 (23%) a DDD unit. Thirteen VVI (5%) and 4 DDD (5.3%) needed reintervention. Lead displacement with reoperation was required for three ventricular leads (1%) and one atrial lead (1.3%). Infection occurred in two WI units (0.77%) and one DDD (1.33%) unit. Muscular stimulation was noticed among three DDD (4%) and nine VVI systems (3.5%). Urgent reprogramming was needed for 23 VVI (9%) and six DDD units (8%). There was no increase in complications with dual chamber pacing compared to single chamber systems.
Automatic Implantable Cardioverter Defibrillator Implantation after Previous Open Heart Surgery: Subcostal Incision and Small Left Anterior Thoracotomy
Authors: SICLARI FRANCESCO , KLEIN HELMUTH
Published: July 2006

In order to avoid the risk of major bleeding with redo sternotomy, an alternative surgical approach for the implantation of an automatic implantable Cardioverter defibrillation (AICD) is presented. A subcostal incision in combination with a small left anterior thoracotomy was used in three patients. The procedure was easy to perform, considerably shorter than a redo sternotomy and well tolerated by the patient. We recommend this approach for A/CD implantation in cases with previous heart operation.
A Study of the Use of Flecainide Acetate in the Long‐Term Management of Cardiac Arrhythmias
Authors: WISEMAN MARTIN N. , ELSTOB JUNE E. , CAMM A. JOHN , NATHAN ANTHONY W.
Published: July 2006

One hundred and sixty‐nine patients with a wide range of cardiac arrhythmias and who had been treated with chronic oral flecainide acetate were reviewed retrospectively. The most common arrhythmia was atrial fibrillation (32%), and 20% of the patient population had the Wolff‐Parkinson‐White syndrome. Five hundred and three treatment episodes were assessed, 254 with flecainide alone or in combination, mean duration 7.3 ± 9.4 months, and 249 without flecainide, mean duration 9.5 ± 12.3 months. The most common dose for flecainide was 200 mg/day (57% of episodes), and it was used alone in 82% of flecainide treatment episodes. Arrhythmia frequency was reduced or abolished in 73% of flecainide treatment episodes, with little difference between arrhythmia groups. Unwanted effects were seen in 14% of flecainide treatment episodes, and half of these cases were managed by dose adjustment. It is concluded that flecainide acetate is effective in a wide range of cardiac arrhythmias, and that long‐term management problems are few.
Revised Implantation Procedure for Programmable Automatic Implantable Cardioverter Defibrillator: Don't Discard the Magnet
Authors: VENDITTI FERDINAND J. , MARTIN DAVID , TSUJI HISAKO , SHAHIAN DAVID M. , BOWEN SUSAN
Published: July 2006

The newest implantable defibrillator (Ventak 1550 AICD) introduces radiofrequency telemetric communication that obviates the need for activation and deactivafion of the device by a magnet during implantation. We present three of our first ten cases of implantation in which difficulties in intraoperative sensing would have been undetected without use of the magnet for audible evaluation of sensing. Based on this experience, we recommend a revised implantation protocol in which audible confirmation of sensing for 30 to 60 seconds by means of a sterile magnet is performed twice (with a pacemaker, if present in DOO or VOO mode): at the time of system test before induction of arrhythmia with testing cables connected to permit recording of rate, morphology, and ECG interpretation channel signals; and after final connection of the leads to the AICD. This simple additional maneuver is a powerful troubleshooting tool during implantation that permits prompt identification of sensing problems.
Oversensing from Electrode ‘Chatter’ in a Bipolar Pacing Lead: A Case Report
Authors: CHEW PAUL H. , BRINKER JEFFREY A.
Published: July 2006

An 81‐year‐old man was treated for high degree AV block and syncope with an AV universal (DDD) pacemaker. Bipolar active fixation atrial and ventricular leads were used. Intermittent Oversensing from the ventricular lead was detected on Holter monitoring following implantation. This resulted in inappropriate inhibition of ventricular pacing. Ventricular electrogram showed spurious signals between 5 mV and 15 mV in magnitude coincident with ventricular lead inhibition. Treatment consisted of reprogramming the device to the VVT mode. Six weeks after implantation normal pacemaker function in the DDD mode was demonstrated on Holter monitoring and inappropriate pacer inhibition could not be demonstrated. We postulate that electrode ‘chatter’ between the cathodal ring electrode and the helix of the ventricular lead resulted in artifactual potentials sufficient to inhibit pacing. We hypothesize that fibrosis and fixation of the ventricular lead tip over a period of weeks eliminated these electromechanical artifacts and resulted in the oversensing problem being self‐limited. Physicians should be aware of electrode‘chatter’as a cause of pacemaker oversensing.
Demonstration of Accessory Pathway Interaction by Computerized Mapping in Preexcitation Syndrome
Authors: CHEN PENG‐SHENG , DEMBITSKY WALTER P. , FLECK R. PETER , CALISI CONSTANCE M. , FELD GREGORY K.
Published: July 2006

While interaction between the normal conduction system and an accessory pathway (AP) has been reported, interaction between two APs has not been well documented. With the assistance of computerized mapping techniques, we recently operated on a patient with two APs. One of these two APs had slow anterograde conduction velocity and was concealed during sin us rhythm and atrial pacing. Intraoperative computerized mapping studies revealed that the interaction between the APs was responsible for the anterograde conduction block of the slow AP during sinus rhythm and atrial pacing. This is the first direct demonstration of inhibition of conduction of one AP by the other AP in a patient with preexcitation syndrome.
Electrophysiological and Anatomical Findings in Heart Transplantation: Experimental Study
Authors: CASTEJON RAFAEL , CABO JAVIER , GAMALLO CARLOS , DIEZ‐PARDO JUAN ANTONIO , CORDOVILLA GREGORIO
Published: July 2006

The diagnosis of acute rejection by electrophysiological methods is based on the fact that signs of rejection such as inflammatory infiltrate, interstitial edema, and mostly myocyte necrosis lead to obligated alterations in electrophysiological properties of the myocardium. In a total of 276 heterotopic abdominal transplants in rats, a noninvasive monitoring of heart allograft rejection by conventional ECG and electrophysiological techniques was performed. The correlation of these findings with pathological studies, including histologic determination of the degree of acute rejection, analysis of weight and cardiac perimeter, and volumetric cell density were also evaluated in 96 of them, 66 were allogeneic and 30 syngeneic. Sensitivity and specificity of the R wave and slew rate was also determined with respect to the Billingham classification. Results of the correlation analysis showed that electrophysiological variations in R wave and slew rate correlated more intensely with changes in volumetric cell density. The greatest sensitivity and specificity was observed in R wave changes in relation to the Billingham classification.
A New Algorithm to Solve Endless Loop Tachycardia in DDD Pacing: A Multi‐Center Study of 91 Patients
Authors: LIMOUSIN M. , BONNET J.L. ,   INVESTIGATORS OF THE MULTICENTER STUDY**
Published: July 2006

ELTs (endless loop tachycardias) are a common occurrence associated with DDD pacing. In order to detect and treat ELTs, an innovative automatic pacemaker algorithm was devised and evaluated. The basic principle of the algorithm rests on the relative stability of the ventriculoatrial conduction time (VACT) during ELTs. ELTs are suspected when the VACT remains stable and adheres to certain programmable limits referred to as VACT stability (16 or 32 msec); it is confirmed when the VACT remains stable after a programmable shortening of the AV delay (AVD) value, referred to as AVD shortening (47 or 63 msec). Ninety‐one patients, 54 males and 37 females, were implanted with such an algorithm‐specific device between January 10 and September 9, 1989. The reasons for implantation were as follows: 55 patients were implanted for AV block, 31 for sinus node dysfunction, and 2 for carotid sinus syndrome. Pacing parameters were programmed to favor ELT initiation (long AVD, short postventricular atrial refractory period [PVARP] and high atrial sensitivity) followed by basic programming of the algorithm (VACT stability set at 16 msec and AVD shortening set at 47 msec. Once this was done, a 24‐hour Holter recording was obtained. Eighty‐eight patients were thus analyzed, three being excluded from the final report due to the poor quality of the Holter tracings. In 43.2% of the sampling (38 patients), multiple episodes of ELT were identified, exhibiting a mean rate of 120 beats/min. In 26 of 38 cases (68.4%), the rate of ELT was found to be slower than the upper rate limit (URL). A total of 1,816 episodes were encountered, representing a mean value of 47.8 ± 78.4 episodes per patient per day (2 to 330 episodes). In 31 patients (81.5%), the algorithm proved to work correctly. For eight patients, some episodes were not terminated by the basic programming. For two of these eight patients, reprogramming the algorithm's parameters (VACT stability to 31 msec and AVD shortening to 63 msec) resulted in a successful diagnosis and termination of ELT.
Promotion of Ventricular Tachycardia Induction by Procainamide in Dogs with Inducible Ventricular Fibrillation Late After Myocardial Infarction
Authors: HUNT GERALDINE B. , ROSS DAVID L.
Published: July 2006

The influence of procainamide on inducible ventricular tachyarrhythmias was evaluated in 35 dogs with experimental myocardial infarction, and 9 normal dogs. Programmed stimulation was performed from the right ventricular apex via a percutaneously positioned electrode catheter, using up to five extrastimuli before and after intravenous administration of procainamide (15 mg/kg). Procainamide Jevels in postinfarct dogs were 8.5 ± 0.7 μg/mL (range 5.3–33.6 μg/mL). Procainamide exerted its greatest effect in postinfarct dogs with reproducible baseline ventricular fibrillation. Six of nine dogs (P < 0.05) with ventricular fibrillation had sustained monomorphic ventricular tachycardia (cycle length: 147 ± 4 msec) induced after procainamide administration. This ventricular tachycardia required significantly more extrastimuli than baseline ventricular fibrillation (3 ± 0.3 extrastimuli before vs 4 ± 0.3 extrastimuli after procainamide). Procainamide never converted ventricular fibrillation to ventricular tachycardia in normal dogs. Procainamide had minimal effect on inducible ventricular tachycardia after myocardial infarction. Ventricular tachycardia induction was abolished in only 2 of 17 dogs despite significant prolongation of electrophysiological parameters. Ventricular tachycardia cycle length, and the number of extrastimuli required were unchanged by procainamide in this subgroup. Conclusion: Ventricular tachycardia is insensitive to the antiarrhythmic properties of procainamide in this model. In contrast, procainamide is able to convert postinfarction ventricular fibrillation to ventricular tachycardia, presumably by promoting sustained, organized reentry. This previously undescribed action is an unusual form of proarrhyfhmic effect, and suggests that this drug should be used cautiously in patients after myocardial infarction.
Lack of Influence of Atrioventricular Delay on Stroke Volume at Rest in Patients with Complete Atrioventricular Block and Dual Chamber Pacing
Authors: OCCHETTA ERALDO , PICCININO CRISTINA , FRANCALACCI GABRIELLA , MAGNANI ANDREA , BOLOGNESE LEONARDO , DEVECCHI PAOLO , ROGNONI GIORGIO , ROSSI PAOLO
Published: July 2006

Dual chamber pacing (DDD) maintains atrioventricular (AV) sequence; AV delay program mobility modifies the relationship between atrial and ventricular contraction. To evaluate the hemodynamic effects of such a modification, ten patients with a DDD unit for complete AV block were studied by time‐motion (M‐mode) and Doppler echocardiography during inhibited ventricular pacing (VVI), atrial‐triggered ventricular pacing (VDDJ and atrioventricular sequential pacing (DVI) at different AV delay (90, 140, 390, 240 msec). A significant improvement in stroke volume (SV) (15%–20%, P < 0.05) was seen during DDD versus VVI pacing; no changes, however, were observed in the same patient with different AV delay or during DVI versus VDD pacing. These data suggest that programming of AV delay does not affect systolic performance at rest; longer diastolic filling times recorded during DDD pacing with “short” AV delay (90–340 msec) do not seem to be a hemodynamically relevant epiphenomenon of PM programming.
Experience and Implantation Techniques with a New Single‐Pass Lead VDD Pacing System
Authors: LONGO EDWARD , CATRINI VINCENT
Published: July 2006

Thirty‐six patients were implanted with a single‐lead atrial‐synchronous ventricular pacing (VDD) system at our center in the first and second phases of a clinical trial between October 1987 and December 1989. The clinical system comprised a pulse generator in conjunction with a pacing lead incorporating two diagonal atrial bipolar (DAB) electrodes designed to lie in the mid‐to upper‐right atrium and a distal tip electrode for ventricular pacing and sensing. Twenty five of the patients had complete heart block, ten had second‐degree block, and one had AV nodal block. A modified Bruce protocol limiting treadmill speed to 1.7 miles per hour was used to establish sinus node competency as evidenced by sustained sinus rate increase in a more‐or‐less linear fashion. The mean acute P wave amplitude measured at implant was 1.66 mV ± 1.04 SD; the mean P wave amplitude (minimum and maximum, both sitting and supine) for all patients at all follow‐up (N = 420) was 1.54 mV ± 0.9 SD. The follow‐up interval for all patients ranged from a minimum of 13 days and a maximum of 762 days, with a mean 0/261 ± 206 days as of December 1,1989. Four dislodgments of the ventricular electrode occurred with the more pliable of two passive fixation mechanisms used on the lead; atrial sensing remained intact at all times with both fixation systems. Changes in atrial sensing threshold were quite frequent during the early follow‐up visits due to electrode movement in the right atrium; however, adequate ventricular tracking of the atrial rate was achieved in all cases once the threshold values were established initially, even though several patients required atrial sensing of 0.2 mV at some of the follow‐up visits. Two patients presented with pacemaker‐mediated tachycardia associated with retrograde conduction, which was resolved with reprogramming; they are presently maintaining atrial synchrony in the VDD mode. Successful single‐lead VDD pacing with consistent P wave sensing has been achieved with this atrial rate responsive system.
Transesophageal Echocardiography for Insertion of a Physiological Pacemaker in Early Pregnancy
Authors: JORDAENS LUC J. , VANDENBOGAERDE JOHAN F. , VAN DE BRUAENE PETER , DE BUYZERE MARC
Published: July 2006

A dual chamber pacemaker was implanted during the first trimester of pregnancy in a patient with second‐degree heart block and syncope. Transesophageal echocardiography was used to confirm satisfactory position in the right atrial appendage.
Three‐Dimensional Electrocardiography of Cardiac Pacing
Authors: TRIGANO JACQUES ALEXANDRE
Published: July 2006

Electrocardiographic evaluation of modern pacing systems requires sustained documentation during iterative programming procedures, exercise testing or Holter monitoring. Documentation of a prolonged period of time in standard electrocardiography is based on horizontal compression. The value and limitations of a vertical compression with no change in horizontal chronology and waveform morphology are evaluated. The signal taken from a selected surface lead is introduced into an oscilloscope triggered by an electrocardiographic event along the horizontal axis. A continuous vertical monitoring provides a vertical superimposition of the consecutive cycles. The brightness is proportional to the amplitude of the signal and introduces a third dimension. The three‐dimensional technique results in an original image allowing report miniaturization at standard 25 or 50 mm/sec paper speed. Appropriate lead selection and use of the brightness as a marker event allow reliable atrial activity identification. In rate responsive pacing evaluation, the procedure is specifically convenient to full disclosure of the chronotropic response. The main limitation is a high sensitivity to noise during recording. Further developments are to be expected based on computer‐assisted electrocardiography.
Nonpharmacological Therapy of Supraventricular Arrhythmias: Surgery and Catheter Ablation Techniques
Authors: SINGER IGOR , KUPERSMITH JOEL
Published: July 2006

Treatment of supraventricular tachyarrhythmias has undergone substantial change and development over the past decade. Pharmacological approaches to management of Supraventricular arrhythmias have been supplanted by nonpharmacoiogicai techniques. These nonpharmacoiogicai techniques are the subject of the present review. The first part of this review will concentrate on the nonpharmacoiogicai techniques available for the treatment of Supraventricular tachycardia, excluding Wolff‐Parkinson‐White syndrome, whereas Part 2 will concentrate on the surgical and the ablative procedures for management of tachycardias associated with Wolff‐Parkinson‐White syndrome. Pacing techniques for termination of supraventricular tachycardias are beyond the scope of this article and will not be included in the discussion.
Self‐Entwinement of an Active Fixation Pacemaker Electrode
Authors: STOUGHTON THOMAS L. , MARTYAK THOMAS E. , GOMEZ ALPHONSE C. , PEARL WILLIAM
Published: July 2006

We report a case in which an active fixation atrial lead tip became entwined on the proximal lead body during implantation. It was not possible to disengage the tip or to remove the resultant Jead loop atraumatically through the insertion site. Removal of the lead was accomplished using a Dotter intravascular snare inserted via a femoral vein, with subsequent successful implantation of a new lead. This unusual technique‐related complication emphasizes the need for meticulous fluoroscopic visualization during lead manipulation.
Entrapment of a Tined Pacemaker Electrode in the Tricuspid Valve. A Case Report
Authors: FRANDSEN FRITS , OXHØJ HENRIK , NIELSEN BJARNE
Published: July 2006

A tined pacemaker electrode was entrapped in the tricuspid valve apparatus. Nonresponding, sustained ventricular tachycardia, and cardiac arrest necessitated forcible removal of the electrode causing partial avulsion of the tricuspid valve. Hemodynamically insignificant tricuspid regurgitation developed subsequently.
Surgical Electrocautery and the Runaway Pacemaker Syndrome
Authors: HELLER LOUIS I.
Published: July 2006

A case of a unipolar surgical electrocautery‐induced runaway pacemaker is described. The single chamber ventricular pacemaker began firing at 140 beats/min with intermittent capture and the abnormal rhythm persisted after cessation of the electrocautery. Emergent explanation of the pulse generator was required.
QT Sensing Rate Responsive Pacing During Subacute Bacterial Endocarditis: A Case Report
Authors: KAYE GERRY C. , BAIG WAZIR , MACKINTOSH ALAN F.
Published: July 2006

A 63‐year‐old woman treated with a QT sensing rate responsive pacemaker following aortic valve replacement developed late subacute bacterial endocarditis. During febrile periods, associated with systemic upset, pacing was physiological as evidenced by an increased heart rate during pyrexia and a decrease when afebrile.
Body Surface Mapping and Nontraditional ECG Leads in Patients with Wolff‐Parkinson‐White Syndrome
Authors: BOCKERIA L.A. , REVISHVILY A. SH. , POLJAKOVA I.P.
Published: July 2006

A method of ECG mapping from 90 points on the chest surface is described in 41 male and 17 female patients, aged 6 to 59 years. All also underwent invasive electrophysiological investigation and intraoperative epicardial mapping. Fifty‐two patients had one, three patients two, and one patient had three anomalous accessory pathways. Two patients had nodoventricular tracts (Mahaim fibers). We distinguished seven zones along the atrioventricular groove (AVG) to compare the data derived from epicardial, endocardial, and body surface mapping. A microcomputer was used for the anaJysis of all ECGs to construct and analyze the isopotential maps. The criterion for localization of the anomalous accessory pathways was determined after analysis of the data from all 58 patients. The localization criterion was the appearance of a minimal deflection (−0.09 ± 0.03 mV) on the surface isopotential maps within the first 0.28 msec of the QHS complex. This criterion for localization of anomalous accessory pathways from the chest surface was proposed on the basis of comparison of data from selective coronary angiography, the ventriculogram, and the chest X ray i.e., radiographic‐topographic‐anatomical data. In 20 patients, 10–20 nontraditional ECG leads were recorded from the chest to reflect the atrioventricular groove. The number of nontraditional ECG leads depended on patient age, weight, and height. Localization of the accessory pathway in one of the seven zones was established by the earliest delta wave and its maximum deviation. It was possible to localize the anomalous accessory pathway and to suspect multiple pathways in 95% of cases using nontraditional ECG leads and the listed criteria. Comparison of results of body surface mapping with X ray‐topographic‐anatomical data made determination of the anomalous accessory pathway possible with a high degree of success. We propose a new system of 10–20 nontraditional ECG leads recording data from the AVG projection onto the chest surface for topical localization of the Kent bundle in one of the seven zones into which the AVG was divided.
Combination of Flecainide and Mexiletine for the Treatment of Ventricular Tachyarrhythmias
Authors: JORDAENS LUC J. , TAVERNIER RENE , VANMEERHAEGHE XAVIER , ROBBENS ERWIN , CLEMENT DENIS L.
Published: July 2006

A combination of oral flecainide and mexiletine was given to 11 patients in whom monotherapy with one of these drugs was ineffective for the suppression of inducible ventricular tachycardia or fibrillation. In eight of 11 studies, combination therapy prevented inducibility of a sustained ventricular tachycardia or resulted in induction of only nonsustained tachycardia (P = 0.0003, when compared to monotherapy). In one patient, a slow ventricular tachycardia was induced. During exercise testing ventricular tachycardia occurred in two of these nine patients, and ventricular fibrillation in another patient. Seven patients received combination on the long term, for a mean of 18 months. One patient had recurrences of ventricular tachycardia which was well tolerated. Another patient had a recurrent episode of ventricular fibrillation, but was successfully resuscitated. Severe congestive heart failure occurred in two patients. ACE inhibitors were given to them and to another four patients. No other important unwanted effects occurred. The combination of mexiletine and flecainide is very effective in suppressing inducible sustained ventricular tachycardia. The efficacy of this combination to prevent recurrences of ventricular tachyarrhythmias is acceptable. Exercise testing is of importance to unmask proarrhythmic effects before discharge from hospital.
Ten‐Years Follow‐Up of 20 Patients with Idiopathic Ventricular Tachycardia
Authors: GOY JEAN‐JACQUES , TAUXE FRANÇOISE , FROMER MARTIN , SCHLÄPFER JÜRG , VOGT PIERRE , KAPPENBERGER LUKAS
Published: July 2006

The follow‐up and characteristics of 20 patients with ventricular tachycardia (VT) and no detectable heart disease is reported. These were 16 men and four women with a mean age of 44 years. Symptoms were present in 18 patients (eight had syncope and ten palpitations or dizziness), VT was sustained in 11 patients and a left bundle branch block morphology with inferior axis was found in 17 patients. In three patients, VT had a right bundle branch block morphology and left‐axis deviation. The VT was inducible in 13 patients during the electrophysiological testing (EP) and was sustained in five patients. Medical treatment was introduced in 19 patients. During a mean follow‐up of 10 years from the onset of the symptoms and 6 years from the EP testing, one patient died suddenly. He had stopped taking amiodarone 5 months before. In seven patients symptoms recurred and were due to discontinuation of therapy in two cases and inefftcacy of previous effective treatment in five patients. After modification of the treatment (three cases), implantation of a pacemaker (one case) and catheter ablation (one case), all patients became asymptomatic. Eleven patients became asymptomatic with the first administered antiarrhythmic therapy. One patient continues to be asymptomatic in spite of discontinuation of his medical therapy. We conclude that patients with VT and no detectable heart disease have a good long‐term prognosis and that appropriate therapy can be found in almost all patients.
Intraventricular Migration of an ICD Patch
Authors: SICLARI FRANCESCO , KLEIN HELMUT , TRÖSTER J.
Published: July 2006

A 42‐year‐old man presented with fever and weight loss 12 months after ICD replacement. After unsuccessful search for an infected focus and a specific antibiotic treatment ICD pocket was explored and Staphylococcus epidermidis was cultured. Following generator explanation fever recurred and at a second operation one ICD patch was found to have perforated in the right ventricular cavity. Explanation of the patches was performed on cardiopulmo‐nary bypass, the patient survived the operation and infection was eradicated.
The Plasma Catecholamine Responses to Ventricular Pacing: Implications for Rate Responsive Pacing
Authors: HULL ROBERT W. , SNOW FRANK , HERRE JOHN , ELLENBOGEN KENNETH A.
Published: July 2006

Many patients with WI and WIR pacemakers will alternate between periods of sinus rhythm and ventricular pacing. These rhythm shifts may be poorly tolerated by some patients. Changes in plasma Catecholamine levels during these rhythm shifts may contribute to these patients’symptoms. We measured blood pressure, ejection fraction and plasma norepinephrine, epinephrine, and dopamine serially in nine patients with normal left ventricular ejection fractions and WI pacemakers during sinus rhythm and at paced rates of 10 beats per minute (bpm) above sinus rates (10 + NSR), 100 bpm, and 130 bpm. The mean norepinephrine level at baseline was 143 ± 16 pg/mL and increased to 166 ± 36 pg/mL at 10 + NSR, 204 ± 47 pg/mL at 100 bpm, and 182 ± 34 pg/mL at 130 bpm. These increases corresponded to mean percent changes from baseline of 17% (P = 0.02), 33% (P = 0.002), and 24% (P = 0.07), respectively. The magnitude of the norepinephrine response was not correlated with the pacing rate. The mean plasma epinephrine level at baseline was 57 ± 6 pg/mL and peaked at 51 ± 12 pg/mL at 10 + NSR, 89 ± 31 pg/mL at 100 bpm and 101 ± 28 pg/mL at 130 bpm. These increases corresponded to mean percent changes from baseline of‐ 10% (P = NS), 30% (P = 0.07), and 89% (P = 0.02), respectively. No trends in the dopamine response to pacing were noted. During ventricular pacing there were no significant changes in mean blood pressure and only slight changes in ejection fraction. The individual percent changes in plasma norepinephrine and epinephrine at 100 bpm were inversely correlated to the changes in systolic blood pressure (R =−0.68, P = 0.06, and R =−0.81, P = 0.03, respectively). These results suggest that plasma norepinephrine and epinephrine increase acutely in response to ventricular pacing at rates commonly seen during rate responsive ventricular pacing.
Entrainment Onset in Atrioventricular Reciprocating Tachycardia: Value in Bypass Tract Localization and Relationship to the Preexcitation Index
Authors: McBRIDE WADE , WELLS PETER J. , BLACK WILLIAM H. , KREMERS MARK S.
Published: July 2006

The timing of entrainment onset has been shown to correlate with the conduction time to critical elements of a tachycardia circuit in a pacemaker model of reentrant ventricular tachycardia (VT). The utility of this method in evaluating clinical reentrant tachycardias was there/ore evaluated in 24 patients with symptomatic Wolff‐Parkinson‐White syndrome and single bypass tracts (left free wall in 17, posteroseptal in 5, anteroseptal in 1, and right free wall in 1). Right ventricular apex (RVA) pacing during orthodromic atrioventricular reentrant tachycardia (oAVRT) at 10–70 msec less than tachycardia cycle length demonstrated concealed entrainment of the tachycardia in all patients studied. An entrainment index (EI), defined as the minimal prematurity of the ventricular stimulus that first resulted in atrial reset, was calculated from multiple entrainments in each patient. The El was 121 ± 25, 83 ± 19, and 55 msec for left free wall, septal, and right free‐wall bypass tracts, respectively (P = 0.004 for difference between left free wall and septal). A corrected EI, derived by subtracting the amount of atrial reset from the EI, gave values of 108 ± 22 and 71 ± 17 msec for left free wall and septal bypass tracts (P = 0.001). These values were compared to the preexcitation index (PI) by linear regression analysis in these patients. The PI correlated closely with both the EI and the corrected EI (r = 0.90 and 0.93, respectively), but the PI could only be derived in 12/17 (71%) left free‐wall tachycardias versus the El in 17/17 (100%) (P < 0.05). Thus, the timing of entrainment onset can be used to calculate a relative conduction time to the tachycardia circuit in oAVRT, thus localizing the bypass tract. This may prove useful in localizing critical components of the reentrant circuit in other clinical tachycardias.
Quantitative Analysis of Wenckebach Behavior in DDD Pacemakers
Authors: HIGANO STUART T. , HAYES DAVID L.
Published: July 2006

Wencke‐bach‐type behavior in P‐synchronous pacing modes allows a gradual transition into 2:1 block. As this behavior is dependent on precise timing intervals, it can be quantitated with mathematical equations. In this report, equations for quantitating the Wenckebach escape rate and the (N + 1)/N block points have been derived. These equations were then used to produce plots of Wenckebach escape rates for given AV intervals, atrial refractory periods, and atrial rates. These equations were validated utilizing a DDD pulse generator interfaced with a patient simulation device. The predicted values for the Wenckebach escape rate and ratio (n = 33) correlated highly with the observed values fr = 0.99, P < 0.0002, and r = 0.97, P < 0.0001, respectively) thereby validating the derived equations. This quantitative analysis has allowed a close look at the pacing behavior between the maximum tracking rate and the 2:3 block point. These equations may be clinically useful for assessing whether a nonfriggering P wave resulted from Wenckebach type block or atrial undersensing and for the more complicated interval analysis in DDDR pacing with rate responsive AV delays and postvenfricular atrial refractory periods.
Electrophysiological Significance of QRS Alternans in Narrow QRS Tachycardia
Authors: PULIGNANO GIOVANNI , PATRUNO NICOLINO , URBANI PAOLA , GRECO CESARE , CRITELLI GIUSEPPE
Published: July 2006

To investigate the electrophysiological significance of QRS alternans during narrow QRS tachycardia, transesophageal atrial pacing and recording was performed in 24 patients with a history of paroxysmal supraventricular tachycardia. Standard electrocardiograms showed ventricular preexcitation in 15 patients and normal QRS pattern in nine patients. The ventriculoatrial interval during tachycardia, as defined by means of transesophageal electrogram, allowed tentative diagnosis of the tachycardia mechanism. A 12‐lead ECG was recorded either during spontaneous or induced tachycardia, as well as during transesophageal atrial pacing at increasing rates. Electrical alternans occurred spontaneously in eight patients (33%, group A): five with accessory pathway reentry (mean VA: 136 ± 43 msec), and three with AV nodal reentry (mean VA: 48.3 ± 12 msec). Tachycardia rate ranged between 170 and 230 beats/mm (mean 200.7 ± 16). In two patients, alternation of the QRS occurred only in the presence of a heart rate exceeding 180 and 190 beats/min, respectively. The amplitude of QRS remained stable during tachycardia in 16 patients (67%, group B): 14 had accessory pathway reentry (mean VA: 137.5 ± 32 msec), and two had AV nodal reentry (mean VA: 45 ± 7 msec). In this group, the tachycardia rate ranged from 150 to 210 beats/min (mean 175 ± 12). Incremental transesophageal atrial pacing up to rates equal to that of tachycardia was performed in five patients from group A and in five patients from group B. Electrical alternans could not be induced in both groups with pacing at progressively increasing rates. In contrast, the phenomenon could be elicited in two patients from group A when an abrupt pacing at the same rate that had showed the spontaneous occurrence of QRS alternans was instituted. This article suggests that alternation of QRS is relatively common during narrow QRS tachycardia. The phenomenon is a rate‐dependent event, unrelated to the substrate of the tachycardia.