bluuebunny/crossref_metadata_2025 huggingface dataset:
Rate Adaptive Atrial Pacing in the Bradycardia Tachycardia Syndrome
Authors: SCHWAAB BERNHARD , FRÖHLIG GERD , SCHWERDT HOLGER , LINDENBERGER IRENE , SCHIEFFER HERMANN
Published: July 2006

In 42 patients (26 men, 16 women; mean age 69 ± 10 years), who were paced and medicated with antiarrhythmic drugs for the bradycardia tachycardia syndrome, chronotropic response and AV conduction with rapid atrial pacing during exercise were studied. Patients were included if they had no second‐ or third‐degree AV block, no complete bundle branch or bifascicular block, and a PQ interval ≤ 240 ms during sinus rhythm at rest. The interval between the atrial spike and the following Q wave (SQ) was measured in the supine position at rest with an AAI pacing rate of 5 beats/min above the sinus rate (SQ‐R+5), and at the end of exercise with 110 beats/min (SQ‐E110). Bicycle ergometry was performed using the Chronotropic Assessment Exercise Protocol with the pacemakers being programmed to AAI with a fixed rate of 60 beats/min. Chronotropic incompetence was defined as peak exercise heart rate: (1) < 100 beats/min; (2) < 75% of the maximum predicted heart rate; or (3) the heart rate at half the maximum workload < 60 + 2 beats/min per mL O2/kg per minute (calculated O2 consumption). During exercise, one patient developed atrial fibrillation. Chronotropic incompetence was present in 71 % (29/41) of the patients according to definition 2, and in 76% (31/41) according to definition 1 or 3. Ten out of 41 patients (24%) exhibited a second‐degree AV block with atrial pacing at 110 beats/min at the end of exercise. Only 9 out of the remaining 31 patients (29%) showed a physiological adaptation of the SQ‐E110, and 21 patients (68%) exhibited a paradoxical increase of the SQ interval with rapid atrial pacing at the end of exercise as compared to the SQ‐R+5. These observations indicate that the pacing system to be used in most patients paced and medicated for the bradycardia tachycardia syndrome should be dual chamber, and the option of rate adaptation should be considered.
Unipolar Waveforms and Monophasic Action Potentials in the Characterization of Slow Conduction in Human Atrial Flutter
Authors: FENELON GUILHERME , BRUGADA PEDRO
Published: July 2006

Anisotropic propagation may be involved in the development of areas of slow conduction in atrial flutter. We evaluated monophasic action potentials (MAPs) and simultaneous unipolar (0.2–400 Hz) and bipolar electrograms from multiple atrial sites of patients undergoing RF ablation of idiopathic atrial flutter. Nine patients (mean age 46 ± 20 years) with typical atrial flutter (one with both types) were studied. Unipolar electrograms with triphasic complexes of small amplitude and with a slow, negative deviation of the baseline preceding the rS deflection indicated transversal conduction in relation to the orientation of cardiac fibers; smooth rS complexes longitudinal conduction; QS complexes onset of activation; and R complexes end of activation or collision. In all patients with typical atrial flutter, slow conduction occurred in the corridor between the inferior vena cava, the tricuspid annulus, and the coronary sinus. Transversal conduction was observed in this area, whereas the remaining sites showed longitudinal conduction. Anatomically guided RF ablation was successful in five patients. Transversal conduction was recorded in all successful sites. In the patient with atypical atrial flutter, slow conduction was noted in the high lateral right atrium, also exhibiting transversal conduction. Ablation at this area terminated the arrhythmia. All the areas of transversal conduction during flutter displayed longitudinal conduction after restoration of sinus rhythm. MAPs were normal in all patients during atrial flutter and sinus rhythm, even at the areas where transversal conduction was recorded. These findings suggest that anisotropic propagation is involved in the genesis of functionally determined areas of slow conduction during typical atrial flutter.
Fast Fourier Transform Analysis of Ventricular Fibrillation Intervals to Predict Ventricular Refractoriness and Its Spatial Dispersion
Authors: WANG LEXIN , LI CHUAN YONG , YONG AH CHOT , KILPATRICK DAVID
Published: July 2006

A technique of fast Fourier transform analysis has been used to derive mean ventricular fibrillation (VF) intervals, and to confirm that these VF intervals predict ventricular refractory periods. Twenty episodes of VF were induced by a rapid ventricular pacing in 12 sheep. VF activations in a 10‐second period were simultaneously acquired from 64 epicardial sites with an electrode sock. The VF electrograms were analyzed by a fast Fourier transform analysis. The dominant peak frequency of the VF spectrum in each epicardial site was converted into milliseconds and served as a mean VF interval. The dominant peak frequency of VF electrograms ranged from 8.1 to 11.5 Hz, and the corresponding mean VF intervals were 87 to 124 ms. In five sheep, the mean VF intervals and the effective refractory periods were determined by the extrastimulus technique obtained from 29 epicardial sites. There was a very good correlation between the two parameters when the effective refractory periods were determined at a basic cycle length of 300 ms (r = 0.89, P < 0.001) and 400 ms (r = 0.87, P < 0.001), respectively. VF was induced twice in eight sheep. The maximum difference in the mean VF intervals between the two VF episodes in the same sheep was 3 ms (P > 0.05). In conclusion, mean VF intervals determined by the fast Fourier transform analysis have a good reproducibility and a good correlation with ventricular refractory periods measured by the classic extrastimulus technique. The mean VF intervals could serve as an index of ventricular refractoriness.
Effect of a Single Element Subcutaneous Array Electrode Added to a Transvenous Electrode Configuration on the Defibrillation Field and the Defibrillation Threshold
Authors: KÜHLKAMP VOLKER , DÖRNBERGER VOLKER , KHALIGHI* KOUROSH , MEWIS CHRISTIAN , SUCHALLA RALPH , ZIEMER* GERHARD , SEIPEL LUDGER
Published: July 2006

Even with the use of biphasic shocks, up to 5% of patients need an additional subcutaneous lead to obtain a defibrillation safety margin of at least 10 J. The number of patients requiring additional subcutaneous leads may even increase, because recent generation devices have a < 34 J maximum output in order to decrease their size. In 20 consecutive patients, a single element subcutaneous array lead was implanted in addition to a transvenous lead system consisting of a right ventricular (RV) and a vena cava superior lead using a single infraclavicular incision. The RV lead acted as the cathode; the subcutaneous lead and the lead in the subclavian vein acted as the anode. The biphasic defibrillation threshold was determined using a binary search protocol. Patients were randomized as to whether to start them with the transvenous lead configuration or the combination of the transvenous lead and the subcutaneous lead. In addition, a simplified assessment of the defibrillation field was performed by determining the interelectrode area for the transvenous lead only and the transvenous lead in combination with the subcutaneous lead from a biplane chest X ray. The intraoperative defibrillation threshold was reconfirmed after 1 week, after 3 months, and after 12 months. The mean defibrillation threshold with the additional subcutaneous lead was significantly (P = 0.0001) lower (5.7 ± 2.9 J) than for the transvenous lead system (9.5 ± 4.6 J). With the subcutaneous lead, the impedance of the high voltage circuit decreased from 48.9 ± 7.4 Ω to 39.2 ± 5.0 Ω. In the frontal plane, the interelectrode area increased by 11.3%± 5.5% (P < 0.0001) and in the lateral plane by 29.5%± 12.4% (P < 0.0001). The defibrillation threshold did not increase during follow‐up. Complications with the subcutaneous electrode were not observed during a follow‐up of 15.8 ± 2 months. The single finger array lead is useful in order to lower the defibrillation threshold and can be used in order to lower the defibrillation threshold.
Assessment of the Subclavian Vein in Patients with Transvenous Pacemaker Leads
Authors: ZUBER MICHEL , HUBER PETER , FRICKER URS , BUSER PETER , JÄGER KURT
Published: July 2006

Thrombosis of the subclavian vein can occur after the implantation of transvenous pacemaker electrodes. Although this is seldom followed by thromboembolic complications, it can cause problems when replacing the leads. To assess the impact of the pacemaker leads on the subclavian vein, a study using nonin‐vasive duplex sonography was performed on 56 patients at an average of 41 months after the implantation. Forty‐three percent of the patients were found to have a normal function of the subclavian vein, 46% developed pathological changes of the vessel wall, and 11% occluded. These changes rarelv caused symptoms, and, therefore, had little clinical significance. Moreover, the occlusion rate was found independent of the patient's age, the patient's sex, the number of electrodes, the procedure of implantation, and even the time from implantation. As a result, the clinical diagnosis of occlusion is uncertain. Therefore, duplex sonography is recommended as an easy means of excluding a totally thrombosed subclavian vein prior to replacing pacemaker leads.
Slow Potential‐Guided Radiofrequency Catheter Ablation in Atrioventricular Nodal Reentrant Tachycardia: Characteristics of the Potential Associated with Successful Ablation
Authors: YAMABE HIROSHIGE , OKUMURA KEN , TSUCHIYA TAKESHI , TABUCHI TOSHIFUMI , IWASA ATSUSHI , YASUE† HIROFUMI
Published: July 2006

To examine the characteristics of Haïssaguerre's slow potential (SP) specific to effective catheter ablation of the slow pathway in AV nodal reentrant tachycardia, the properties of SP and its recording site ware analyzed in 52 patients who underwent successful SP‐guided ablation. The properties of SP included the ratio of the amplitude of SP to that of atrial potential (A)(SP/A), the SP duration, the interval between His‐bundle potential (HP) and SP (HP‐SP), the interval between A and SP (A‐SP), the interval between SP and ventricular potential (V) (SP‐V), and the ratio of A‐SP to the interval between A and the V (A‐SP/A‐V). The SP recording site was determined by the ratio of the amplitude of A to that of V (A/V) and by the relative position of the ablation catheter on X ray (right anterior oblique projection), expressed as the ratio of the distance between the coronary sinus ostium and SP site to that between the coronary sinus ostium and HP recording site (relative SP position). Twenty‐eight slow pathways were ablated with a single energy application, while the other 24 required applications ≥ 2. In all successful applications, SP/A, SP duration, HP‐SP, A‐SP. SP‐V, A‐SP/A‐V, A/V, and relative SP position were 51 %± 25%, 28 ± 5 ms, ‐11 ± 9 ms, 57 ± 25 ms, 68 ± 13 ms, 46%± 9%, 15%± 13%, and 51%± 13%, respectively. A significant correlation was observed between the relative SP position and A‐SP, and between the relative SP position and A‐SP/A‐V (r = 0.60 and 0.37, respectively), while it was not between the relative SP position and HP‐SP, nor between the relative SP position and SP‐V. When the characteristics of SP were comparatively analyzed between the effective and ineffective applications in 24 patients in whom applications ≥ 2 were required, there was no difference observed in HP‐SP, A‐SP, SP‐V, A‐SP/A‐V, and A/V. However, SP/A, SP duration, and the relative SP position in the effective applications were all greater than those in the ineffective ones (56%± 20% vs 35%± 18%, P < 0.001; 29 ± 4 vs 26 ± 5 ms, P < 0.01; and 52%± 15% vs 33%± 11%, P < 0.001, respectively). These results indicate that SP with an amplitude over a half of A amplitude and recorded at the mid‐septum of the tricuspid annulus can be a marker for successful slow pathway ablation. Although the local atrial electrogram appears late as the SP recording site shifts to the lower position, the timing of SP relative to HP and V remained unchanged, suggesting that SP is independent of the local atrial activation.
Low Energy Intracardiac Cardioversion of Persistent Atrial Fibrillation
Authors: SANTINI MASSIMO , PANDOZI CLAUDIO , TOSCANO SALVATORE , CASTRO ANTONIO , ALTAMURA GIULIANO , JESI ANNA PATRIZIA , GENTILUCCI GIUSEPPE , VILLANI MAURO , SCIANARO MARIA GARMELA
Published: July 2006

The aims of the study were to verify the efficacy and safety of low energy internal Cardioversion (LEIC) in patients with persistent at rial fibrillation (AF) and to identify the factors affecting the at rial defihrillation threshold (ADT). Forty‐nine patients with persistent (lasting ≥ 10 days) AF underwent LEIC. In each patient, two 6 Fr custom‐made catheters with large active surface areas were positioned in the coronary sinus (cathode) and the lateral right wall (anode), respectively, for shock delivery, and a tetrapolar lead was placed in the fight ventricular apex for R wave synchronization. Truncated, biphasic (3 ms+3 ms). exponential shocks were used, beginning at 50 V and increasing in steps of 50 V until sinus rhythm had been restored. Mild sedation (diazepam 5 mg IV) was administered to 12 patients. Sinus rhythm was restored in all the subjects with mean voltage and energy levels of 352.0 ± 80.3 V and 8.2 ± 3.4 J, respectively. The ADT in patients pretreated with amiodarone (6.4 ± 1.8 J) was lower than that of patients who had not received any antiarrhythmic drugs (9.2 ± 3.7) (P = 0.04). No ventricular arrhythmias were induced by any of the atrial shocks, and no other complications were observed. During a mean follow‐up of 162.9 ± 58.7 days, AF recurred in 21 (43%) patients; 71% of these occurred in the first week after Cardioversion. LEIC is effective in restoring sinus rhythm in patients with persistent AF. The technique seems to be safe and does not require general anesthesia or, in most cases, sedation. Patients pretreated with amiodarone have lower ADTs.
Early Results of AV Sequential Pacing on Left Ventricular Outflow Obstruction after Senning Procedure
Authors: AVASARALA KISHOR , CASE CHRISTOPHER , WIENECKE MATTHEW , ZEIGLER VICKI , LAI LINDA , GILLETTE PAUL
Published: July 2006

Dual chamber pacing was shown to decrease left ventricular outflow tract (LVOT) obstruction in patients with hypertrophic cardiomyopathy 30 years ago. We report early results of AV sequential pacing from the LV apex in a patient with transposition of the great arteries who is post‐Senning procedure. LVOT obstruction resulted from septal deviation and systolic anterior motion of the mitral valve. Pacing was indicated for sinus node dysfunction. AV sequential pacing with a short optimal A V interval of 60 ms demonstrated a 45% reduction in the degree of LVOT obstruction. This article suggests that LVOT obstruction after the Senning procedure can be palliated by asynchronous septal contraction induced by A V sequential pacing, even if the activation is from LV apex, and avoid or postpone surgery in selected situations.
Radiofrequency Catheter Ablation of Atrioventricular Junctional (“AV Nodal”) Reentrant Tachycardia in Patients with Implantable Cardioverter Defibrillators
Authors: KILBORN MICHAEL J. , McGUIRE MARK A.
Published: July 2006

Catheter ablation of tachycardias has been undertaken successfully in patients with ICDs without damage to the ICD or lead. Ablation of the slow AV nodal pathway, however, is technically challenging because the lead of the ICD lies close to the ablation site. We report successful ablation of AV Junctional reentrant tachycardia (AVJRT) in three patients with ICDs, In all cases, the ablation site was within a few millimeters of the ICD lead. The ablation was successful in all cases and did not cause damage to the ICD or lead. The patients have remained free of recurrence of AVJRT during a mean follow‐up of 12 months.
A Complication of Pacemaker Lead Extraction: Paradoxical Embolism of a Lead Fragment in a Leg Artery
Authors: DIEUZAIDE P. , SAVON N. , CHALVIDAN T. , LeTALLEC L. , DeHARO J.C. , DJIANE P.
Published: July 2006

Extraction of three chronically implanted pacemaker leads was performed via the implant vein in a 71‐year‐old man. One of the leads broke in the subclavian scar tissue. The lead fragment migrated into the left peroneotibial trunk artery. Transesophageal echocardiography showed patent foramen ovale associated with right‐to‐left atrial shunt. This complication of lead extraction is discussed along with the role of echocardiography prior to lead removal.
Abnormal Vasovagal Reaction, Autonomic Function, and Heart Rate Variability in Patients with Paroxysmal Atrial Fibrillation
Authors: LOK NGAI‐SANG , LAU CHU‐PAK
Published: July 2006

The aim of this study was to evaluate the cardiovascular autonomic function and vasovagal reaction in patients with paroxysmal atrial fibrillation without significant structural heart disease. Twenty‐eight patients with paroxysmal atrial fibrillation (9 patients were categorized to have autonomic‐mediated atrial fibrillation while atrial fibrillation in other patients was nonautonomic mediated) and 19 normal control subjects were recruited. Cardiovascular autonomic function tests included measuring heart rate response to standing, deep breathing, Valsalva maneuver, baroreflex sensitivity, 24‐hour heart rate variability, and also head‐up tilt test. Compared with normal subjects, no significant autonomic dysfunction was found in patients with autonomic‐mediated and nonautonomicmediated atrial fibrillation. All subjects had negative baseline tilt test. With isoproterenol provocation, six patients developed atrial fibrillation. Four of 9 patients and 3 of 19 patients with autonomic mediated and nonautonomic mediated atrial fibrillation had a positive tilt test respectively, while none occurred in the controls. A significant percentage (32%) of patients with paroxysmal atrial fibrillation had episodes of atrial fibrillation provoked by changes in autonomic tone, although there was no underlying abnormal cardiac autonomic function nor sympathetic‐parasympathetic imbalance. A heightened susceptibility to vasovagal cardiovascular response may have important implications on the occurrence and symptomatology of patients with paroxysmal atrial fibrillation.
Venous Access Thrombosis Detected by Transcutaneous Vascular Ultrasound in Patients with Single‐Polyurethane‐Lead Permanent Pacemaker
Authors: LIN LI‐JEN , LIN JIUNN‐LEE , TSAI WEI‐CHUAN , TENG JENG‐KAI , TSAI LIANG‐MIING , CHEN JYH‐HONG
Published: July 2006

In order to assess the incidence of significant venous thrombosis after transvenous permanent pacemaker implantation, transcutaneous ultrasound studies were performed in 109 consecutive patients with single‐polyurethane‐lead pacemakers. Ultrasonic evaluation was found to be a good noninvasive method in assessing the veins. Six patients (5.5%) were found to have significant venous obstruction in the subclavian vein. However, none of them were symptomatic. No difference in the incidence of venous obstruction was found, based on the age, duration of implantation, operative technique, potentially thrombogenic factors including atrial fibrillation, diabetes mellitus, hypertension, heart failure and end‐stage renal disease.
High Energy Radiofrequency Catheter Ablation for Common Atrial Flutter Targeting the Isthmus between the Inferior Vena Cava and Tricuspid Valve Annulus Using a Super Long Tip Electrode
Authors: IESAKA YOSHITO , TAKAHASHI ATSUSHI , GOYA MASAHIKO , YAMANE TEIICHI , TOKUNAGA TAKESHI , AMEMIYA HIROSHI , FUJIWARA HIDEOMI , NITTA JUNICHI , NOGAMI AKIHIKO , AONUMA KAZUTAKA , HIROE MICHIAKI , MARUMO FUMIAKI , HIRAOKA MASAYASU
Published: July 2006

There have been controversies concerning the optimal target sites and approaches in radiofre‐quency catheter ablation of common atrial flutter. We attempted high energy radiofrequencv catheter ab‐lation targeting the isthmus between the inferior vena cava and tricuspid valve annulus (IVC‐TV isthmus) with a super long (8 mm) tip electrode, and compared the efficacy of this anatomical approach with the electrophysiological approach targeting the posteroseptal right atrium posterior to the coronary sinus us‐ing a standard 4‐mm tip electrode. Atrial flutter was successfully ablated in 12 of 12 patients (100%) with‐out recurrence with the anatomical approach, while, in 7 of 9 patients (64%) with 2 recurrences with the electrophysiological approach. In comparison of ablation data between the anatomical and electrophysi‐ological approaches, there were significant differences in the mean number of application pulses (anatomical vs electrophysiological: 2.3 ± 0.8 vs 9.9 ± 6.4, P < 0.01), applied wattage (39 ± 12Wvs24 ± 6W.P < 0.01), applied energy per application (1.986 ± 426 / vs 659 ± 323 J. P < O.O1), fluoroscopic time (26 ± 11 min vs 74 ± 30 minutes, P < 0.01), and procedure time (59 ± 8 min vs 181 ± 53 min. P < 0.01). In conclusion, the anatomical approach is superior to the electrophysiological one with respect to proce‐dure and radiation time, and linear ablation at the IVC‐TV isthmus with an 8‐wm tip electrode and high energy application is highly effective and safe.
ICD Restudy: Results and Potential Benefit from Routine Predischarge and 2‐Month Evaluation
Authors: HIGGINS STEVEN L. , RICH DAVID H. , HAYGOOD JAMES R. , BARONE JULIE , GREER SHERIE L. , MEYER DAVID B.
Published: July 2006

Evaluation of ICD function can now be performed noninvasively with intravenous sedation. To determine the value of follow‐up electrophysiological studies for ICD implants, we performed a retrospective review of predischarge and 2‐month ICD restudies, identifying critical problems uncovered. Of the 123 patients implanted, 122 had a predischarge study, 105 had both predischarge and elective 2‐month follow‐up studies, and 1 patient expired prior to restudy. Patients who underwent 2‐month studies for nonelective indications (e.g., frequent shocks) were excluded from analysis. Programming changes were made in 62% of the predischarge studies (n = 122) and 70% of the elective 2‐month studies (n = 105). The average number of programming changes per study was 1.3 for predischarge testing and 1.1 for 2‐month testing. The most common changes at predischarge testing were adjustment of the tach‐yarrhythmia rate cutoff (35%) and at 2‐month study, reprogramming of bradycardia pacing parameters (41%). Of the patients who underwent both predischarge and 2‐month testing, 91% had programming changes in at least one of their restudies. Of 227 restudies performed, 18 studies in 14 patients yielded 24 critical findings which included: DFT increases to ≥ 25 J (n = 13); sensing abnormalities of induced ventricular arrhythmia (n = 6); dislodged lead (n = 2); and serious pacemaker interactions (n = 3). Six of these critical cases (5% of total patients) required reoperation. The data suggests that routine ICD restudy is a valuable tool for management of the ICD patient. Additionally, ICD restudy is likely to increase the diagnostic yield of clinically silent critical system problems that could result in device failure.
Benign Prognosis of Early Sinus Node Dysfunction After Orthotopic Cardiac Transplantation
Authors: HEINZ GOTTFRIED , KRATOCHWILL CHRISTOPH , KOLLER‐STRAMETZ JEANETTE , KREINER GERHARD , GRIMM MICHAEL , GRABENWOGER MARTIN , LAUFER GUNTHER , GOSSINGER HEINZ
Published: July 2006

Previous reports raised concern about the prognosis of patients with sinus node (SN) dysfunction after cardiac transplantation and led to a low threshold for permanent pacemaker (PM) placement at most institutions. The present study addresses the survival in patients with normal and impaired post operative SN function and the effect of permanent pacing with respect to overall and cardiac mortality. There were 120 patients with normal (corrected SN recovery time < 520 ms, group I) and 47 patients with impaired SN function (corrected SN recovery time < 520 ms and/or sinus arrest ± escape rhythms). Pacing support was deemed unnecessary in 23 of 47 patients with SN dysfunction (group II; asymptomatic SN bradycardia and corrected SN recovery time 3,812 ± 5,800 ms) while a total of 24 patients had PM placement a mean of 29 ± 44 days after transplantation (symptomatic bradycardia or absence of sinus rhythm at discharge, group III). Patients were followed for a mean of 46.7 months. Thirty‐five deaths occurred during the study period. Sixteen deaths were cardiac but none were causally related to the SN dysfunction (graft failure due to rejection or atheropathy n =14; myocardial infarction n = 2). Four of these cardiac deaths were sudden and all occurred in the presence of widespread structural abnormalities (rejection/vasculopathy/myocardial infarction). SN dysfunction was not related to overall (P = 0.25) or cardiac mortality (P = 0.33). Regarding either endpoint, patients who had permanent PM placement did no belter than their unpaced counterparts in group II (P = 0.53 and P = 0.33, overall and cardine mortality, respectively). Likewise, survival did not differ between groups 1 and III for either endpoint (P = 0.77, P = 0.65, respectively). These data suggest that patients with mild SN abnormality, who are in sinus rhythm at the time of discharge, can be followed by observation without specific therapy.
Safety of Transvenous Low Energy Cardioversion of Atrial Fibrillation in Patients with a History of Ventricular Tachycardia: Effects of Rate and Repolarization Time on Proarrhythmic Risk
Authors: SIMONS GRANT R. , NEWBY KEITH H. , KEARNEY MARGARET M. , BRANDON MARY J. , NATALE ANDREA
Published: July 2006

The objective of this study was to assess the safety and efficacy of transvenous low energy cardioversion of atrial fibrillation in patients with ventricular tachycardia and atrial fibrillation and to study the mechanisms ofproarrhythmia. Previous studies have demonstrated that Cardioversion of atrial fibrillation using low energy, R wave synchronized, direct current shocks applied between catheters in the coronary sinus and right atrium is feasible. However, few data are available regarding the risk of ventricular proarrhythmia posed by internal atrial defibrillation shocks among patients with ventricular arrhythmias or structural heart disease. Atrial defibrillation was performed on 32 patients with monomorphic ventricular tachycardia and left ventricular dysfunction. Shocks were administered during atrial fibrillation (baseline shocks), isoproterenol infusion, ventricular pacing, ventricular tachycardia, and atrial pacing. Baseline shocks were also administered to 29 patients with a history of atrial fibrillation but no ventricular arrhythmias. A total of 932 baseline shocks were administered. No ventricular proarrhythmia was observed after well‐synchronized baseline shocks, although rare inductions of ventricular fibrillation occurred after inappropriate T wave sensing. Shocks administered during wide‐complex rhythms (ventricularpacing or ventricular tachycardia) frequently induced ventricular arrhythmias, but shocks administered during atrial pacing at identical ventricular rates did not cause proarrhythmia. The risk of ventricular proarrhythmia after well‐synchronized atrial defibrillation shocks administered during narrow‐complex rhythms is low, even in patients with a history of ventricular tachycardia. The mechanism of proarrhythmia during wide‐complex rhythms appears not to be related to ventricular rate per se, but rather to the temporal relationship between shock delivery and the repolarization time of the previous QRS complex.
Evaluation of an Ultrasonically Guided Venepuncture Technique for the Placement of Permanent Pacing Electrodes
Authors: NASH ANTONY , BUREELL CHRISTOPHER J. , RING NICHOLAS J. , MARSHALL ANDREW J.
Published: July 2006

We have evaluated a method of puncturing the subclavian vein in its extrathoracic portion using on ultrasound guidance system. Seventy consecutive patients requiring permanent pacemakers were included in the study. The method was successful in 56 (80%) cases (23 dual chamber systems) and unsuitable or unsuccessful in 14 (20%) cases (2 dual chamber systems). The time taken to achieve a successful cannulation of the vein was similar to that taken with conventional subclavian Venepuncture (average time taken for each Venepuncture WAS 31 seconds, range 5–130 seconds). There was a significant “learning curve” in that nearly all of the unsuccessful cases were in the first half of the series. There were no major complications. Computerized Tomography (CT) confirms that the point of entry into the subclavian vein using this technique lies outside the thoracic cavity, thereby minimizing the risk of pneumothorax. This approach to the subclavian vein is an easy technique to learn, with few immediate complications and there maybe less chance of lead fracture due to subclavian crush in the longer term.
Optimal Cardiac Pacing in Patients with Coronary Artery Disease
Authors: BAROLD S. SERGE , BAROLD HELEN S.
Published: July 2006

Pacemaker patients with coronary artery disease and angina pectoris fare better with devices providing AV synchrony and rate increase on exercise provided the programmed upper rate is not excessive. Optimal programming requires knowledge of the factors influencing pacemaker rate response, MVO2 and cardiac sympathetic activity. Inappropriately high rates during rate adaptive pacing can be controlled by new multisensor systems with sensor cross‐checking to avoid false positive responses with inappropriate increases in the pacing rate. Permanent pacing in patients with intractable angina who are unsuitable for interventional procedures permits more aggressive pharmacological therapy.
Pneumothorax: An Unusual Cause of ICD Defibrillation Failure
Authors: LURIA DAVID , STANTON MARSHAL S. , ELDAR MICHAEL , GLIKSON MICHAEL
Published: July 2006

We describe two patients with defibrillation failure of implantable cardioverter defibrillators (ICDs) resulting from large left pneumothoraxes following subclavian vein puncture during the implantation. Following pneumothorax drainage, low defibrillation thresholds (DFTs) were attained without further manipulations. The absence of other signs and symptoms of pneumothorax and the presence of satisfactory pacing function during the procedure, resulted in a significant delay in diagnosis. Pneumothorax should be included in the differential diagnosis when unexpected high DFTs are found during ICD implantation or predischarge testing. This complication is avoidable by a different surgical approach, cephalic vein cutdown.
Sensing Lead Insulation Defect Resulting in a Damage of the ICD Pulse Generator Case
Authors: GUMMERT JAN , KRAUSS BEATE , HUTSCHENREITER WINERIED , HAMBRECHT RAINER , MOHR ERIEDRICH W.
Published: July 2006

Eight months after ICD implantation with an electrically active case the patient presented with ICD system sensing failure. Upon re‐operation, we found an insulation defect of the proximal sensing lead and the generator case showed arc marks suggesting a short circuit between the sensing lead and case. the generator was replaced, the original sensing lead insulated, and a new sensing lead inserted. Bench testing of the explanted generator showed a damaged internal circuitry. Proximal lead insulation defects combined with electrically active cases may result in damage of the case. The potential damage of internal circuitry warrants generator replacement.
A Cause of Sudden Death: Rupture of Thoracic Aortic Aneurysm
Authors: SAKAKIBARA YUZURU , ENOMOTO YOSHIHARU , MIHARA WAHEI , GOMI SEIGO , MITSUI TOSHIO
Published: July 2006

Sudden death occurred during antihypertcnsive therapy of a Stanford type A dissecting aortic aneurysw. Hemodynamic and electrocardiograpbic events were recorded including deterioration of ventricular fibrillation 4 minutes after rupture.
Scoring Method for Assessing Rate Adaptive Pacemakers: Application to Two Different Activity Sensors
Authors: GARRIGUE STÉPHANE , CHAIX CHRISTOPHE , GENCEL LAURENT , JAÏS PIERRE , DARTIGUES JEAN‐FRANCOIS , HAÏSSAGUERRE MICHEL , CLÆMENTY JACQUES
Published: July 2006

To optimize programming of rate adaptive pacemakers (RAPs), we explored a new mathematical method to assess the performance of RAPs during daily‐life tests, using customized Windows‐based software. By stepwise discriminant analysis and linear regression, this method allows calculation of the acceleration and deceleration capacity of pacemakers and their general behavior during effort and recovery phases. Twenty‐three patients (10 females and 13 males; 68 ± 8 years) with chronic atrial fibrillation and a slow ventricular response were evaluated. They randomly received an accelerom‐eter‐controlled VVIR Dash Intermedics pacemaker (10 patients) or a vibration piezoelectric‐controlled WIR Sensolog III Siemens pacemaker (13 patients). All patients underwent the same test protocol: 6 minutes walking, 1.5 minutes climbing stairs, 1.5 minutes descending stairs, and 0.5 minutes sit‐ups. By definition, the pacemaker responsiveness slope was programmed so that the heart rate response of paced patients during the walking test corresponded best to that of healthy controls. The slope was left unchanged for the other tests. We considered four scores: an acceleration score (EA score), an effort rate score (ER score), a deceleration score (RD score), and a recovery rate score (RR score). Scores ranged from 10 (hypochronotropic behavior of the pacemaker) to +10 (hyperchronotropic behavior), based on daily‐life tests of 15 healthy controls (7 females and 8 males, 65 ± 9 years). A score of 0 represented exact concordance with healthy controls. During stair descent, the Sensolog III produced excessive acceleration (EA score =+2.9 ± 1.1) compared to: (1) stair climbing (EA score =−4.0 ± 1.9; P = 0.01, with the same pacemaker); and (2) the Dash (+1.8 ± 1.9; P = 0.04) and healthy controls (P = 0.02). The sit‐up tests revealed a hypochronotropic response of both pacemakers compared to healthy controls, with a larger difference for the Sensolog III (EA score =−2.0 ± 5.8; P = 0.04; RD score =−6.8 ± 3.8; P = 0.02). We conclude that activity‐driven pacemakers can accommodate brief activities, except for isovolumetric exercise such as sit‐ups. During daily activities, accelerometer‐driven pacemakers seem to provide a heart rate response closer to that of healthy controls. Our new mathematical analysis is a simple and reproducible method for evaluating and quantifying the efficacy of any sensor‐driven pacemaker.
Effects of Procainamide on the Excitable Gap Composition in Common Human Atrial Flutter
Authors: JALIL ELISE , FRANC PIERRE Le , LEBEAU RÉAL , MOLIN FRANCK , COSTI PAOLO , KÚS TERESA
Published: July 2006

The composition of the excitable gap (EG) in common atrial flutter (AFI) was determined before and during infusion of procainamide (PA) in 9 patients (6 men and 3 women; age 70 ± 7 years). The EG was determined by introducing a premature stimulus after every 20th AFI complex detected using a quadripolar electrode catheter placed just above the tricuspid valve. Diastole was scanned in 2‐ to 4‐ms decrements to the atrial effective refractory period (ERP). The relationship between the coupling interval and the return cycle length (CL) determined a reset‐response curve (RRC), which described the EG. PA (15 mg/kg) was administered during AFl over 30 minutes and RRC was repeated at maximum AFI CL. PA prolonged AF1 CL from 227 ± 29 to 296 ± 62 ms (P < 0.01) but did not terminate AFI. ERP during AFl prolonged from 169 ± 24 to 219 ± 41 ms (P < 0.01). Control EG was 57 ± 16 ms or 25%± 6% of AFl CL and on PA EG was 77 ± 30 ms (P = 0.01), which was still 26%± 7% of the CL. Without drug, RRC was mixed in eight cases demonstrating an EG composed of fully excitable tissue (10 ± 4 ms or 19%± 10% of the EG) and partially refractory tissue (48 ± 18 ms), PA did not change the duration of the fully excitable region (13 ± 10 ms or 19%± 15% of EG). Peak PA plasma concentration was 47 ± 20 μmol/L. PA prolonged AFI CL, ERP, and EG duration but did not change the proportion of AFI CL occupied by the EG. The persistence of fully excitable tissue at the head of the wavefront in the presence of PA may largely explain its inefficacy in the acute termination of common AFl.
Hemodynamic Benefits of Right Ventricular Outflow Tract Pacing: Comparison with Right Ventricular Apex Pacing
Authors: de COCK CAREL C. , MEYER ALBERT , KAMP OTTO , VISSER GEES A.
Published: July 2006

To assess optimal hemodynamics in relation to stimulation site during right ventricular pacing, 17 consecutive patients who underwent cardiac catheterization were studied. In all patients, right ventricular apex and right ventricular outflow tract stimulation was performed at 85, 100, and 120 beats/min. Cardiac index at both pacing sites was compared using the left ventricular outflow tract continuous wave Doppler technique. Comparison of the two stimulation sites demonstrated that right ventricular outflow tract pacing resulted in a higher cardiac index at 85 beats/min (2.42 ± 1.2 vs 2.04 ±1.0 L/min per m2, P < 0.002) at 100 beats/min (2.78 ± 1.4 vs 2.35 ± 1.1 L/min perm2, P < 0.001) and 120 beats/min (3.00 ± 1.5 vs 2.61 ± 0.9 L/min perm2, P < 0.001). From a total of 51 paired observations, 45 showed an increase in cardiac index during outflow tract pacing as compared to apex pacing. Right ventricular outflow tract pacing at 120 beats/min resulted in a lower cardiac index than right ventricular apex pacing in patients with significant coronary artery disease and/or impaired left ventricular function (ejection fraction ≤ 50%), whereas right ventricular outflow tract pacing produced higher cardiac indices in the absence of these abnormalities. Right ventricular outflow tract pacing resulted in higher cardiac indices as compared to apex pacing in all other subgroups at all other pacing sites tested. It is concluded that stimulation of the right ventricular outflow tract offers a significant hemodynamic benefit during single chamber pacing as compared to conventional apex pacing, particularly in the absence of significant coronary artery disease and/or left ventricular dysfunction.
JT Dispersion in Wolff‐Parkinson‐White Syndrome: Effect of Eccentric Ventricular Depolarization on the Dispersion of Repolarization
Authors: BALAJI SESHADRI , SOKOLOSKI MARY C. , CASE CHRISTOPHER L. , GILLETTE PAUL C.
Published: July 2006

There is much interest in QT dispersion for noninvasive risk stratification of patients at risk of arrhythmias. However, little is known about the genesis of abnormal QT dispersion. In particular, whether eccentric ventricular depolarization, as seen in preexcitation, can lead to abnormal dispersion of repolarization is unknown. We studied 24 children aged 1–19 years (mean ± SD, 11 ± 5 years) with manifest preexcitation due to Wolff‐Parkinson‐White syndrome who had successful catheter ablation. Standard ECGs done preablation, early postablation (< 1 week), mid postablation (> 1 week, < 2 months), and late postablation (> 2 months) were reviewed. The QRS duration prior to ablation ranged from 90–160 ms (mean ± SD, 123 ±21 ms). On the preablation ECG, the JT and JTc dispersions showed no relationship to the QRS duration (r = 0.04 and 0.07, respectively). There was no change in JT dispersion when the preablation (42 ±15 ms) ECG was compared to early (43 ±15 ms), mid (44 ±13 ms), and late postablation (48 ± 19 ms) ECGs. There was no significant change in JTc dispersion as well. Thus, JT dispersion is unrelated to QRS duration and unaffected by catheter ablation in patients with Wolff‐Parkinson‐White syndrome. Eccentric ventricular depolarization does not lead to abnormal dispersion of repolarization.
Rhythm Management in Atrial Fibrillation—With a Primary Emphasis on Pharmacological Therapy: Part 1
Authors: BLITZER MARK , COSTEAS CONSTANTINOS , KASSOTIS JOHN , REIFFEL JAMES A.
Published: July 2006

Atrial fibrillation (AF) is the most common, sustained, symptomatic tachyarrhythmia that clinicians are called upon to manage. Management strategies include ventricular rate control coupled with anticoagulation, versus restoration and maintenance of sinus rhythm. Rate control may be achieved pharmacologically, with agents that impair AV nodal conduction directly and/or by increasing parasympathetic/sympathetic balance, or by modifying or ablating the AV nodal region anatomically. Rhythm control may be achieved by electrical or pharmacological conversion followed by maintenance of sinus rhythm by pharmacological (or occasionally ablative) therapies. This article will present current approaches to rate and rhythm control issues in AF. Part 1, the current manuscript, details approaches to rate control and includes a drug selection algorithmic conclusion. It also introduces the subject of the pursuit of sinus rhythm. Parts 2 and 3, to be published in subsequent editions of PACE, will deal with therapeutic measures to restore and maintain sinus rhythm.
Stepwise Strategy on the Cost of Risk Stratification After Acute Myocardial Infarction: A Retrospective Simulation Study
Authors: OLIVEIRA MÁRIO , STAUNTON ANNE , CAMM A. JOHN , MALIK MAREK
Published: July 2006

Stratification of postinfarction patients at high risk of mortality and/or other adverse events can be improved by combining several prognostic markers. As the clinical impact of risk stratification has only recently emerged in prospective trials, there are a lack of data regarding the cost‐effectiveness of multimarker strategies. This study performed a comprehensive search of a postinfarction database and simulated different risk stratification strategies involving left ventricular ejection fraction, signal‐averaged electrocardiography, Holler monitoring, and heart rate variability, The parameters were assessed before discharge in 417 survivors of acute myocardial infarction followed‐up for 1 year. Cardiac mortality was used as the clinical endpoint. A statistical computer model of a stepwise strategy using every feasible sequence of the four tests was used and, based on prices derived from European and American centers, the cost estimates of all possible combinations were compared. During the 1 year after myocardial infarction there were 24 cardiac deaths (5.8%). In all the population, 6% had all four tests positive (cardiac mortality 20%); 25% had at least three tests positive (cardiac mortality 12.5%); 58% had at least two tests positive (cardiac mortality 8.3%); and 92% presented with at least one test positive (cardiac mortality 6.3%). The cost of performing all the tests ranged between $398 and ≥1,887 for each patient. However, by selecting patients according to a stepwise strategy, the costs ranged from $96 (≥ 1 test positive) to $510 (for the least expensive sequences of four tests positive). For each of the centers considered, the costs resulting from the risk stratification protocol were determined by the number of variables combined and sequences of tests adopted. Thus, a stepwise strategy using the combination of all four parameters, starting with analysis of Holter variables and finishing with signal‐averaged electrocardiography, appears to be the most appropriate and the least expensive approach for selecting patients at high risk of cardiac death.
Accidental Entry of an Implantable Cardioverter Defibrillator Lead into the Left Hepatic Vein Detected by Transesophageal Echocardiography
Authors: ORIHASHI KAZUMASA , MATSUURA YUICHIRO , SUEDA TAIJIRO , SHIKATA HIROO , MITSUI NORIMASA , SUESHIRO MASAFUMI
Published: July 2006

We report a case of accidental entry of an implantable Cardioverter defibrillator lead into the hepatic vein, which was not noted on fluoroscopy but was apparent when transesophageal echocardiography (TEE) was used incidentally. The lead was depicted in the hepatic vein as strongly echogenic, accompanied by an acoustic shadow. Additional bending of the stylet was helpful for successful advancement of the lead. TEE provides additional information in such cases, although indications for its use should be explored because of its possible complications.
Lipoinjection as a Treatment of Pacemaker Pocket Neuralgia
Authors: GUBNER RICHARD E. , SANDS MURRAY P. , GROSS JAMES R.
Published: July 2006

Chronic severe pacemaker pocket neuralgia secondary to inadequate subcutaneous tissue between the pacemaker and overlying skin typically is treated by surgical pocket revision or relocation of the system. A case of this complication successfully treated by lipoinjection is reported. Additional experience is needed to confirm the usefulness of the technique as a means of providing symptomatic relief without the risks associated with more invasive procedures.
Reposition of an Implantable Cardioverter Defibrillator Generator from an Abdominal Pocket to a Subpectoral Location Using the Existing Electrode
Authors: JENSEN STEEN M.
Published: July 2006

The size of today's implantable cardioverter defibrillator generators makes a Subpectoral position feasible even when an existing generator is located abdominally. Elective replacement with reposition of the generator from an abdominal to a subpectoral pocket without implantation of another electrode is described.
Comparison of the Effects of AV Nodal Ablation Versus AV Nodal Modification in Patients with Congestive Heart Failure and Uncontrolled Atrial Fibrillation
Authors: TWIDALE NICHOLAS , MCDONALD TOM , NAVE KELLY , SEAL AUDREY
Published: July 2006

Radiofrequency (RF) catheter ablation of the atrioventricular node (AVN) and implantation of a ventricular pacemaker can improve cardiac performance in patients with congestive heart failure (CHF) and uncontrolled atrial fibrillation (AF). Alternatively. RF catheter modification of the A VN has been proposed to slow ventricular response during AF without requirement for permanent pacing. Among 44 consecutive patients (mean age 69.7 ± 10.2 years) with drug resistant chronic AF, 22 (group I) had AVN ablation with permanent ventricular pacemaker implantation, while 22 patients had attempted AVN modification. Complete AV block was obtained in all group I patients while only seven (32 %) A VN modification patients (group II) had permanent slowing of ventricular rate. Among patients in group I, mean left ventricular ejection fraction (EF) increased from 32.2%± 8.8% before ablation to 41.9%± 14.6% 4‐weeks postablation (P < 0.01); exercise tolerance time (ETT) increased from 2.9 ± 2.2 minutes to 4.5 ± 2.9 minutes (P < 0.01); and quality‐of‐life score decreased from 66.1 ± 22.6 to 36.9 ± 17.1 (P < 0.01). By comparison, there was only a small increase in ETT in the seven successful group II patients (2.4 ± 1.8 minutes to 3.0 ± 1.9 minutes; P < 0.05) and there was no significant change in EF or quality‐of‐life. While AVN ablation can occasionally have transient adverse effects, it is more effective than AVN modification for improving cardiac performance in selected patients with CHF and AF.