bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity to Orthostatic Stress and β‐Receptor Activation in Patients with Isoproterenol‐Induced Vasovagal Syncope: A Case Controlled Study
Authors: SHEN WIN‐KUANG , REA ROBERT F. , BEINBORN DOUGLAS , LOHSE CHRISTINE M. , HODGE DAVID O. , LOW PHILLIP A. , HAMMILL STEPHEN C.
Published: July 2006

Cardiomotor and vasomotor responses were assessed during isoproterenol tilt‐induced vasovagal reaction in patients with a history of syncope. In a case controlled study, all patients and controls were subjected to a standard protocol: baseline supine (10 min), baseline tilt (70±, 45 min), isoproterenol supine (0.05 μg/kg per min, 10 min), and isoproterenol tilt (70±, 10 min). The participants were 11 consecutive patients referred for syncope evaluation (5 men, 6 women; mean age, 34.1 ± 10.4 years; range, 18–56 years) and 11 age and sex matched controls (5 men, 6 women; mean age, 35.5 ± 12.2 years; range, 19–63 years). On‐line, beat‐to‐beat measurements of cardiomotor functions (heart rate, stroke volume, and cardiac output) and vasomotor functions (systolic, mean, and diastolic blood pressures and total peripheral resistance [TPR]) were detected noninvasively by volume clamp photoplethysmography and impedance cardiography. Patients and controls had similar cardiomotor and vasomotor responses during passive tilt and during isoproterenol infusion in the supine position. Immediately after tilt during isoproterenol infusion and before the onset of symptoms, decreases in vasomotor functions were significant in study patients when compared with those in controls; whereas responses in cardiomotor functions were similar between the two groups. When compared with baseline supine findings, TPR decreased by 56.5%± 10.9% and 29.5%± 23.3% in the patient population and controls, respectively (P = 0.005). When compared with isoproterenol supine findings, TPR decreased by 27.5%± 22.8% in the study patients and increased by 22.6%± 48.1% in the controls (P = 0.005). The inability to overcome isoproterenol‐induced vasodilatation during orthostatic stress played an important role in the initiation of a vasovagal response. These observations hold the key to early detection of hemodynamic changes and potential therapeutic interventions before patients become symptomatic.
Intravenous Amiodarone Suppression of Electrical Storm Refractory to Chronic Oral Amiodarone
Authors: KAVESH NEAL G. , OLSOVSKY MARY R. , FREUDENBERGER RONALD S. , CONTE JOHN V. , PETERS ROBERT W. , SHOROFSKY STEPHEN R. , GOLD MICHAEL R.
Published: July 2006

We report the case of an electrical storm in a cardiac arrest survivor with an ICD, in whom chronic oral amiodarone failed to suppress ventricular arrhythmias, and in whom intravenous amiodarone resulted in stability for 6 weeks prior to successful cardiac transplantation. Intravenous amiodarone can be successful in suppressing life‐threatening ventricular arrhythmias, even when chronic oral amiodarone is unsuccessful.
Rate Adaptive Dual Chamber Pacing: Inappropriate Rate Response due to Pseudomalfunction of the QT Biosensor
Authors: DIONISIO PEDRO , STROOBANDT ROLAND , VANDENBULCKE FILIEP , SINNAEVE ALFONS
Published: July 2006

Inappropriate tachycardias may be observed in patients with DDDR pacemakers equipped with an activity sensor and a QT sensor due erroneous T wave sensing, provoked by drug treatment that prolongs cardiac repolarization.
Torsades de Pointes Ventricular Tachycardia Induced by Clarithromycin and Disopyramide in the Presence of Hypokalemia
Authors: HAYASHI YUJI , IKEDA UICHI , HASHIMOTO TOHRU , WATANABE TOKUMITSU , MITSUHASHI TAKESHI , SHIMADA KAZUYUKI
Published: July 2006

We report a 76‐year‐Old woman who developed TdP ventricular tachycardia induced by combined use of clarithromycin and disopyramide. She had a history of myocardial infarction 5 years earlier and has taken disopyramide for supraventricular arrhythmias. In addition, she had taken clarithromycin for upper respiratory tract infection. On admission, an ECG showed prolongation of QTc interval to 0.71 seconds and self‐terminating TdP occurred several times. Disopyramide was metabolized by the cytochrome enzyme CYP3A4 and clarithromycin competitively inhibits this enzyme, probably resulting in an increase in plasma concentration of disopyramide. We should consider this possibility when prescribing clarithromycin in combination with antiarrhythmic agent disopyramide.
Significant Complications Can Occur With Ischemic Heart Disease and Tilt Table Testing *
Authors: LEMAN ROBERT B. , CLARKE ELIZABETH , GILLETTE PAUL
Published: July 2006

We present an elderly patient who had syncope, with known coronary artery disease and a conduction abnormality. Because of a possible vasovagal reaction, the patient underwent a tilt table test prior to evaluation of ischemia or her LV function. During the tilt table test on isoproterenol, the patient developed ventricular fibrillation which was corrected immediately by cardioversion. Subsequently, the patient was found to have significant coronary artery disease which was treated with stenting and angioplasty. After treatment, there were no inducible arrhythmias on full dose isoproterenol. This case reports a significant complication that may occur when tilt table testing with isoproterenol and ischemia.
Replacing Abdominally Implanted Defibrillators: Effect of Procedure Setting on Cost
Authors: VORPERIAN VICKEN R. , LAWRENCE SHERI , CHLEBOWSKI KAREN
Published: July 2006

Although most ICDs are currently placed using a pectoral approach, there exists a large population of patients with abdominally implanted ICDs who will require device replacement due to a depleted battery. The purpose of this study was to compare the cost, convalescence, and complication rate of replacing abdominally implanted ICDs in the OR versus the EP laboratory. Between August 1993 and September 1994, we prospectively enlisted nine consecutive patients who presented for their second ICD generator replacement and who had a prior generator replacement in the OR 3–4 years earlier. The mean age of the patients was 63 ± 17 years and their mean ejection fraction was 37%± 15%. ICD replacement was performed in the EP laboratory and consisted of explanting the old device, electronic interrogation the lead system, and confirmation of defibrillation thresholds prior to implanting a new device. Local anesthesia was provided by lidocaine infiltration and sedation was achieved with intravenous (IV) midazolam and fentanyl.

Following the procedure, the patients were returned to an outpatient monitored setting for 4 hours and were then discharged. Comparisons of the health care charges for the same procedure performed in the two different settings revealed a significant reduction in physician fees (from $3,621 ±$556 to $2,179 $577, P < 0.05), in hospital charges (from $5,811 ±$1,102 to $2,306 ± 696, P < 0.05), and in total charges (from $9,431 ±$1,375 to $4,541 ±$1,010, P < 0.05), exclusive of ICD cost, when the procedure was formed on an outpatient basis in the EP laboratory. Inpatient days averaged 3.0 ± 0.3 when the procedure was performed in the OR. On long‐term follow‐up there were no complications following abdominal ICD generator replacement in the OR (mean follow‐up, 39 ± 2 months) or in the EP laboratory (mean follow‐up, 42 ± 4 months). Thus, ICD replacements in the EP laboratory cost less than in the OR due to significantly lower physician fees, hospital charges, and a shorter postprocedural convalescence.
Paired Ventricular Pacing: An Alternative Therapy for Postoperative Junctional Ectopic Tachycardia in Congenital Heart Disease
Authors: KOHLI VIKAS , YOUNG MING‐LON , PERRYMAN RICHARD A. , WOLFF GRACE S.
Published: July 2006

junctional ectopic tachycardia (JET) is one of the most life‐threatening postoperative arrhythmias in children with congenital heart disease, and medical management is difficult. Paired ventricular pacing (PVP) may provide a safe alternative mode of management. We evaluated the safety and efficacy of PVP for the management of postoperative JET in patients with congenital heart disease. A retrospective collection of data was done from 1981–1995. PVP was successfully tried in five postoperative patients (age range: 37 days to 22 years, median: 10 months). Onset of JET was 3–60 hours (mean ± SD, 19 ± 23 hours) postoperatively. The maximal JET rate was 261 ± 39 beats/min. PVP was used as the first line of management in three patients and was successful in all patients. It resulted in an instantaneous increase in blood pressure from 66 ± 9 to 94 ± 15 mmHg (42% increase) and was required for 12 ± 14 hours (range 2–36 hours). No complications were noted. Therefore, in our experience, this is a safe alternative modality for the control of postoperative JET.
Complications Related to Permanent Pacemaker Therapy
Authors: KIVINIEMI MIKKO S. , PIRNES MARKKU A. , ERÄNEN H. JAAKKO K. , KETTUNEN RAIMO V.J. , HARTIKAINEN JUHA E.K.
Published: July 2006

This study evaluates complications related to permanent endocardial pacing in the era of modern pacemaker therapy. There is only limited information available about the complications related to modern cardiac pacing. Most of the existing data are based on the 1970s and are no longer valid for current practice. The recent reports on pacemaker complications are focused on some specific complication or are restricted to early complications. Thus, there are no reports available providing a comprehensive view of complications related to modern cardiac pacing. Four hundred forty‐six patients, who received permanent endocardial pacemakers between January 1990 and December 1995 at Kuopio University Hospital, were reviewed retrospectively using patient records. Attention was paid to the occurrence of any complication during the implantation or follow‐up. An early complication was detected in 6.7%, and 4.9% of patients were treated invasively due to the early complication. Late complication developed in 7.2% and reoperation was required in 6.3% of the patients. Complications related to the implantation procedure occurred in 3.1%. Inadequate capture or sensing was observed in 7.4% of the patients. Pacemaker infection was detected in 1.8% and erosion in 0.9% of the patients. An AV block developed in 3.6% (1.6%/year) patients who received an AAI(R)‐pacemaker due to sick sinus syndrome. There was no mortality attributable to pacemaker therapy. A great majority (68%) of the complications occurred within the first 3 months after the implantation. Complications associated to modern permanent endocardial pacemaker therapy are not in‐frequent.Elevan percent of patients needed an invasive procedure due to an early or late complication.
Atrial Ectopy Originating from the Posteroinferior Atrium During Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia
Authors: TSUCHIYA TAKESHI , OKUMURA KEN , TABUCHI TOSHIFUMI , IWASA ATSUSHI , OHGUSHI MASAMICHI , YASUE HIROFUMI , HONDA TOSHIHIRO , HONDA TAKASHI , HAYASAKI KAZUYA
Published: July 2006

Atrial ectopy sometimes appears during RF ablation of the slow pathway in patients with atrioventricular nodal reentrant tachycardia (AVNRT). However, its origin, characteristics, and significance are still unclear. To examine these issues, we analyzed 67 consecutive patients with AVNRT (60 with slow‐fast AVNRT and 7 with fast‐slow AVNRT), which was successfully eliminated by RF ablation to the sites with a slow potential in 63 patients and with the earliest activations of retrograde slow pathway conduction in 4 patients. During successful RF ablation, junctional ectopy with the activation sequence showing H‐A‐V at the His‐bundle region appeared in 52 patients (group A) and atrial ectopy with negative P waves in the inferior leads preceding the QRS and the activation sequence showing A‐H‐V at the His‐bundle region appeared in 15 patients (group B). Atrial ectopy was associated with (10 patients) or without junctional ectopy (5 patients). Before BF ablation, retrograde slow pathway conduction induced during ventricular burst and/or extrastimulus pacing was more frequently demonstrated in group B than in group A (9/15 [60%] vs 1/52 [2%], P < 0.001). Successful ablation site in group A was distributed between the His‐bundle region and coronary sinus ostium, while that in group B was confined mostly to the site anterior to the coronary sinus ostium. In group B, atrial ectopy also appeared in 21 % of the unsuccessful RF ablations. In conclusion, atrial ectopy is relatively common during slow pathway ablation and observed in 8% of RF applications overall and 22% of RF applications that successfully eliminated inducible AVNRT. Atrial ectopy appears to be closely related to successful slow pathway ablation among patients with manifest retrograde slow pathway function.
Analysis of Heart Rate Variability Five Minutes Before the Onset of Paroxysmal Atrial Fibrillation
Authors: FIORANELLI M. , PICCOLI M. , MILETO G.M. , SGRECCIA F. , AZZOLINI P. , RISA M.P. , FRANCARDELLI R.L. , VENTURINI E. , PUGLISI A.
Published: July 2006

Background: Various experimental and clinical observations suggest changes in sympathetic and vagal neural regulatory mechanisms play a critical role in altering cardiac electrical properties and favor the occurence of arrhythmic events. There is limited information about the influences of the autonomic tone on the development of episodes of paroxismal atrial fibrillation in patients with no evidence of organic heart disease. The aim of this study was to investigate changes in sympatho‐vagal balance 5 minutes before the onset of atrial fibrillation. Methods: We evaluated 28 patients with no history of heart disease who were not undergoing pharmacological treatment and who had at least one episode of paroxysmal atrial fibrillation recorded during an 24‐hour ECG Holter monitoring. We analyzed values of frequency domain heart rate variability parameters 5 minutes before the onset of atrial fibrillation (prefa period) compared to an equivalent period at least 1 hour after from atrial fibrillation (random period). Results: Thirty‐six episodes of atrial fibrillation were recorded and our results showed we had two types of episodes. Eighteen were classified as Type A, in which we had an increase of low frequency (LF) (79.15 ± 10.76 in comparison with 62.64 ± 19.55) (P = 0.004) and a decrease of high frequency (HF) (20.82 ± 10.74 in comparison with 37.64 ± 20.20) (P = 0.004) consistent with an increase of sympathetic tone; and 18 were classified as Type B in which there was a decrease of LF (62.82 ± 15.38 in comparison with 85.97 ± 8.48) (P < 0.001), and an increase of HF (36.79 ± 14.72 compared with 14.01 ± 8.48) (P < 0.001), consistent with an increase of parasympatetic tone. Conclusion: We observed abrupt changes in sympatovagal balance in the last 5 minutes preceeding an episode of atrial fibrillation. This can be related to a double behavior in the neurogenic drive: in Type A episodes there is an increase of the LF spectrum, LF:HF ratio, and a decrease of the HF spectrum consistent with an increase of neurogenic sympathetic drive; in Type B episodes there is a reduction of the LF spectrum, LF/HF ratio, and an increase of HF spectrum consistent with an enhancement of the neurogenic parasympathetic drive. In some patients, we found that the two mechanisms operate during different hours of the day and that sometimes there is an increase of sympathetic tone, and in the same instances an increase of parasympathetic tone. Heart‐rate variability measures fluctuation in autonomic inputs to the heart rather than the mean level of autonomic impulse; autonomic imbalance is probably more important than the vagal or sympatethic drive alone.
Clinical Surveillance of a Tined, Bipolar, Steroid‐Eluting, Silicone‐Insulated Ventricular Pacing Lead
Authors: GLIKSON MICHAEL , HYBERGER LINDA K. , HITZKE MARY K. , KINCAID DANIEL K. , HAYES DAVID L.
Published: July 2006

Since 1990, 1,068 Medtronic 5024 bipolar, silicone‐insulated, tined, steroid‐eluting ventricular leads have been implanted at the Mayo Clinic (Rochester, MN) and Midelfort Clinic (Eau Claire, WI). Implantation data were favorable: median pacing thresholds of 0.5 V at 0.5 ms, median R wave of 13.4 mV, and median impedance of 593 Ω. Of the 2.1% acute lead‐related complications (dislodgment, microdislocation, diaphragmatic pacing, and undersensing), 1.2% necessitated reoperation. This rate is lower than that in most published series of other leads. During a median follow‐up of 23 months (up to 76 months), 12 (1.1 %) chronic lead‐related complications (high thresholds, loss of capture, and undersensing) and no instances of definite or suspected lead material failure occurred. This rate is much lower than that in studies of other leads. Thus, the 5024 lead combines the reliability of silicone insulation with a low rate of chronic complications that is probably the result of its steroid elution. No evidence of failure of lead material has appeared up to 6 years after implantation.
The Chick Embryo Heart as an Experimental Setup for the Assessment of Myocardial Remodeling Induced by Pacing
Authors: GROBÉTY MICHEL , SEDMERA DAVID , KAPPENBERGER LUKAS
Published: July 2006

The mechanisms regulating remodeling of the heart are not well understood and only rarely investigated for pacing. We therefore developed a model based on the well‐established chick embryo heart preparation. Hamburger Hamilton 21 stage Leghorn chick embryos were used. Access to the heart was obtained after having dissected the shell membranes. The electrodes (platinum wires) were placed in ovo: the anode an the vitelline membrane and the cathode at different sites of the heart (sinus venosus, base/apex of the ventricle). Sensing and stimulation thresholds were measured. Survival of the paced chick was studied. Among 30 chick embryonic hearts, the stimulation thresholds were 1.4 mV ± 0.5 SD for the atrium, 2.6 V ± 1.4 SD at the base, and 3.2 V ± 1.5 SD at the apex of the ventricle, while the sensing signals were 1.3 mV ± 0.5 SD at the atrium, 19.6 mV ± 4.1 SD at the base, and 21.6 mV ± 3.9 SD at the apex of the ventricle. Continuous pacing (pacing rate = intrinsic rate ± 10%) could be maintained for 1.5 hours ± 0.5 SD at the atrium, 8.9 hours ± 0.7 SD at the base of the ventricle, and 7.9 hours ± 1 SD at the apex of the ventricle up to death of the embryos. By using intermittent electrical stimulation, the association of 5 minutes on/5 minutes off pattern during 18 hours and 5 minutes on/15 minutes off, during 30 hours resulted in an effective pacing period of 19 hours in 60% of the experiments, reflecting 15 cell turnover cycles. This experimental setup will allow the study of morphological, metabolic, and molecular bases of ventricular remodeling induced by electrical stimulation.
Immediate and Persistent Complete Heart Block Following a Horse Kick
Authors: BENITEZ R. MICHAEL , GOLD MICHAEL R.
Published: July 2006

Nonpenetrating chest trauma has been reported to cause acute and transient disorders of impulse formation and propagation, including intraventricular conduction delay and heart block. We report a case of immediate and sustained complete heart block following blunt chest injury.
Shear Syndrome: The Worst Case Scenario of Crush Syndrome
Authors: MALIK AMIR Z. , BILFINGER THOMAS V. , VLAY STEPHEN C.
Published: July 2006

Shear syndrome is described as a complication of crush syndrome. In addition to compression of and injury to the electrode, complete transection occurs. In this case, the free end migrated to the pulmonary artery with the potential for further complications.
A Case of Dislodged Atrial Screw‐In Lead with Migration to the Ventricle 1 Year Postoperatively
Authors: NAKAZATO YUJI , NAKATA YASURO
Published: July 2006

We report a rare case of a 53‐year‐old woman with a dislodged atrial screw‐in lead that migrated to the ventricle 1 year after pacemaker implantation. While such an event is quite unusual, we should be aware of its possibility.
Implantable Cardioverter Defibrillators and Cellular Telephones: Is There Any Interference?
Authors: OCCHETTA ERALDO , PLEBANI LAURA , BORTNIK MIRIAM , SACCHETTI GAUDENZIO , TREVI GIAMPAOLO
Published: July 2006

The aim of our study was to consider cellular telephone interference using different cellular telephones and implantable cardioverter defibrillator (ICD) models. Thirty (26 men, 4 women) patients with ICDs were considered during follow‐up. The ICD models were: Telectronics (7), CPI (7), Medtronic (7), Ventritex (5), and Ela Medical (4). All patients were monitored with surface ECG; permanent telemetric endo‐ECG monitoring was activated. Then, the effect of two different European telephone systems were tested: TACS system (Sony CM‐R111, 2 W power) and GSM system (Motorola MG1–4A11, 2 W power). For both systems, the effect during call, reception, active conversation (dialogue), and passive conversation (listening) were observed. Cellular telephones were located first in contact with the programming head, then near the leads system, and lastly, in the hands of the patient. At the end of the evaluations, memories were interrogated again to check for false arrhythmia detections. In five of these patients during arrhythmia induction at device implant (first implant or ICD replacement), we also evaluated possible interference between cellular telephones in the reception phase and the ventricular fibrillation detection phase of the ICD. All evaluated models showed significant noise in the telemetric transmission when the cellular telephone (both TACS and GSM) was located near the ICD and the programming head; noise was particularly significant during call and reception, in most cases leading to loss of telemetry. No false arrhythmia detections have been observed during tests with cellular telephones located on the ICDs. During tests performed with cellular telephones located near the leads or in the hands of patients, no telemetric noises or false arrhythmia detections were observed. During induced ventricular fibrillation and cellular telephones in reception mode near the device, the arrhythmia recognition was always correct and not delayed. In conclusion, present ICD models seem to be well protected from electromagnetic interference caused by European cellular telephones (TACS and GSM), without under‐/oversensing of ventricular arrhythmias. However, cellular telephones disturb telemetry when located near the programming head. ICD patients should not be advised against the use of cellular telephones, but it has to be avoided during ICD interrogation and programming.
A Randomized Controlled Clinical Trial Comparing Ventricular Fibrillation Detection Time Between Two Transvenous Defibrillator Models
Authors: KÜHLKAMP V. , MORTENSEN P. , KIRSTEIN P. , den DULK K. , HOFFMAN E. , WILBER D. , HIGGINS S. , KÜHL M. ,   FOR THE ACUTE VENTAK AV INVESTIGATOR GROUP
Published: July 2006

The Ventak AV is an implantable cardioverter defibrillator with dual chamber pacing capability. Features include detection and treatment of ventricular arrhythmias, detection of atrial arrhythmias, as well as dual chamber pacing. The objective of the investigation was to verify the efficacy of the Ventak AV in detecting ventricular fibrillation in the presence of dual chamber pacing. Thirty‐three patients, who were to receive an implantable defibrillator were randomized (1:1) in a paired comparison study to the Ventak AV (study device) and the Ventak Mini (control) during defibrillation threshold testing. In order to create a “worst case scenario” for sensing of ventricular fibrillation, pacing was performed at high lower rate limit values (Ventak AV DDD pacing at 150/min, Ventak Mini at VVI 100/min). Ventricular fibrillation was induced and the randomized device was allowed to detect and treat the arrhythmia. This test was repeated for each patient using the alternate device in a randomized order, such that all patients were tested with both devices. The mean ventricular fibrillation detection time for the Ventak AV was 2.0 ± 0.11 seconds and for the control device the detection time was 1.8 ± 0.11 seconds (P = 0.26). Appropriate tachyarrhythmia therapy decision was documented in all episodes for both devices. The study patient population demonstrated equivalent ventricular fibrillation detection time between the Ventak AV and the Ventak Mini. The Ventak AV demonstrated effectiveness in detecting ventricular fibrillation in the presence of high rate dual chamber pacing.
Dual Chamber Pacing for Neurally Mediated Syncope with a Prominent Cardioinhibitory Component
Authors: SHAH CHETAN P. , THAKUR RANJAN K. , XIE BAIYAN , PATHAK PRITI
Published: July 2006

The role of cardiac pacing for treatment of recurrent neurally mediated syncope (NMS) remains controversial. We hypothesized that dual chamber pacing in NMS patients with a prominent cardioinhibitory component may be beneficial. Twelve patients (mean age = 37.8 ± 17 years, range 15–78 years, 7 men and 5 women) with a mean of 4 ± 2.2 episodes of syncope underwent tilt table evaluation. Patients were passively tilted to 70° head‐up position for 20 minutes and then returned to the supine position. Isoproterenol was then infused at 1–2 μg/min to increase heart rate by ≥ 25% and tilt was repeated. Patients lost consciousness after 16 ± 6 minutes of tilt; nine patients had syncope in the baseline state and three during isoproterenol infusion. All patients had at least 5 seconds of asystole with a mean of 9.5 ± 4 seconds (range 5–20 s). A dual chamber permanent pacemaker with a special feature allowing heart rate acceleration in response to bradycardia was implanted in all patients. During a mean follow‐up of 18.6 ± 4.2 months, 11 (92%) of these patients were free of syncope and had negative tilt table test. One (8%) patient had two episodes of syncope. We conclude that dual chamber pacing may be beneficial in patients with NMS with a prominent cardioinhibitory component.
Dual Chamber Pacing with a Single‐Lead DDD Pacing System
Authors: NAEGELI BARBARA , STRAUMANN EDWIN , GERBER ANDREAS , SCHUIKI ERNST , KUNZ MARTIN , NIEDERHÄUSER URS , BERTEL OSMUND
Published: July 2006

The successful application of single‐lead VDD pacing during the last few years has generated the idea of single‐lead DDD pacing. Preliminary data from several single‐lead VDD studies attempting to pace the atrium by a floating atrial dipole are unsatisfactory, causing an unacceptably high current drain of the device. We studied the feasibility as well as the short‐ and long‐term stability of atrioventricular sequential pacing, using a new single‐pass, tined DDD lead. In eight consecutive patients (age 73 ± 16 years) with symptomatic higher degree A V block and intact sinus node function, this new single‐pass DDD lead was implanted in combination with a DDDR pacemaker. Correct VDD and DDD function was studied at implantation; at discharge; and at 1,3, and 6 months of follow‐up. At implant, the atrial stimulation threshold was 0.6 ± 0.1 V/0.5 ms. During follow‐up, the atrial pacing thresholds in different everyday positions averaged 2.1 ± 0.5 V at discharge, 2.9 ± 0.5 V at 1 month, 3.8 ± 0.4 V at 3 months, and 3.4 ± 0.4 V at 6 months (pulse width always 0.5 ms). The measured P wave amplitude at implantation was 4.5 ± 2.2 mV; during follow‐up the telemetered atrial sensitivity thresholds averaged 2.1 ± 0.3 mV. Phrenic nerve stimulation at high output pacing (5.0 V/0.5 ms) was observed in three (38%) patients at discharge and in one (13%) patient during follow‐up; an intermittent unmeasurable atrial lead impedance at 3 and 6 months follow‐up was documented in one (13%) patient. This study confirms the possibility of short‐and long‐term DDD pacing using a single‐pass DDD lead. Since atrial stimulation thresholds are still relatively high compared to conventional dual‐lead DDD pacing, further improvements of the atrial electrodes are desirable, enabling lower pacing thresholds and optimizing energy requirements as well as minimizing the potential disadvantage of phrenic nerve stimulation.
Neurohormonal Profile Before and After β‐Blockade in Patients with Neurocardiogenic Syncope
Authors: ROUL GERALD , RIEHL‐ALEIL VERONIQUE , GERMAIN PHILIPPE , BAREISS PIERRE
Published: July 2006

Our objective was to evaluate the effects of β‐blockers on the neurohormonal profile, particularly vasopressin (VP) release, in vasovagal syncope and to gain further insight on the pathophysiology of this syndrome. Patients (≤75 years) with no cardiovascular, neurological disorders, or contraindications to the use of isoproterenol or β‐blockers and being explored for unexplained syncope were included. An 80± HUT was performed under identical conditions. After a 25‐min period of passive tilt, isoproterenol was infused at a rate of 1–5 μg/mn if required. Two groups matched for age and sex were considered: a HUT‐positive and a HUT‐negative group. The HUT‐positive group was then given β‐blockers, subsequently reassessed, and divided into two subgroups: a β‐blocker nonresponder group and a β‐blocker responder group. Blood samples for assays of norepinephrine (NE), epinephrine (E), and VP were taken at baseline and the end of the procedure. In all, 44 subjects entered the study, 22 in each group. The HUT‐positive group exhibited an obvious lesser increase in plasma NE and a clear‐cut rise in plasma E and VP compared to the HUT‐negative group (P < 0.05). Even though no patient in the HUT‐positive group reported recurrent symptoms under treatment, the second HUT could distinguish two subgroups: a β‐blocker nonresponder group (n = 12) whose HUT remained positive and a β‐blocker responder group (n = 10) whose HUT was normalized. The time course of plasma E and VP during the second HUT was similar to that for the HUT‐positive and HUT‐negative groups. In conclusion, the efficacy of β‐blockers is associated not only with a reduction of the sympathoadrenal stimulation seen in vasovagal syncope but also with a lower release of VP suggesting that low‐pressure baroreceptors might be involved in VP release.
Aortic Input Impedance and Ventriculoarterial Coupling Following Cardioversion/Defibrillation
Authors: BAUERNSCHMITT ROBERT , MEHMANESH HORMOZ , SCHULZ STEPHAN , VAHL CHRISTIAN , LANGE RÜDIGER , HANFLER MICHAEL , MÜLLER ALEXANDER , HAGL SIEGFRIED
Published: July 2006

Defibrillation shocks are commonly used after cardiac surgery or during defibrillator implantation. The hemodynamic consequences of countershocks on circulatory dynamics are not completely understood, and there is a lack of information concerning the effects on ventriculoarterial interaction. The study presented here was performed to assess the influence of defibrillation shocks on arterial hemodynamics and ventriculoarterial coupling. Eight mongrel dogs (weight 15–18 kg) were anesthetized and median thoracotomy was performed. Pressure in the ascending aorta and the left ventricle and flow in the ascending aorta were continuously monitored. After induction of atrial or ventricular fibrillation, termination was achieved by epicardial low energy shocks (atrium, 3J; ventricle. 5J). In an additional attempt ventricular fibrillation was terminated by a high energy shock (34J). Aortic input impedance was calculated by fast‐Fourier‐transformation of aortic flow and pressure signals, while ventriculoarterial coupling was expressed by the ratio of aortic and ventricular end systolic elastance (Ea/Ees). Defibrillation by low energy shocks of atrial or ventricular fibrillation did not result in changes of the aortic impedance spectrum, and ventriculoarterial coupling remained unaltered compared to control conditions. High energy defibrillation, however, resulted in a marked rise in total peripheral resistance (P < 0.03). The ratio of Ea/Ees increased significantly (P < 0.005). These effects were reversible within 15 minutes. Low energy defibrillation does not alter arterial hemodynamics and ventriculoarterial coupling in this experimental setup. High energy defibrillation, however, results in a temporary increase of ventricular load. This finding may be of particular interest in patients with poor left ventricular function.
Blind Axillary Venous Access
Authors: BELOTT PETER H.
Published: July 2006

The axillary vein has been suggested as an alternate site for venous access to avoid the “subclavian crush phenomenon.” Many techniques have been used to access this structure. They include complicated anatomical landmarks, contrast venography, Doppler, and ultrasound. A simple technique using the basic anatomical landmark of the deltopectoral groove and a blind venous stick has been used successfully in 165 of 168 consecutive pacemaker and ICD procedures; there were only three failures. These required an alternate approach. With a thorough knowledge of the regional anatomy, the axillary vein can be safely used as a primary site of venous access.
Treatment of Advanced Atrioventricular Block with Beta‐Adrenergic Blockade Therapy
Authors: ABE HARUHIKO , HANADA HIDEYUKI , KOHSHI KIYOTAKA , NAKASHIMA YASUHIDE
Published: July 2006

A 26‐year old woman, who experienced syncope associated with advanced AV block, was referred for further evaluation. Electrophysiological study showed normal SA and AV node physiology. Syncope associated with advanced AV block on the electrocardiogram was induced by head‐up tilt test. Oral propranolol therapy completely prevented the AV block and syncope induced by head‐up tilt. The physician should be aware of advanced AV block associated with neurocardiogenic syncope, especially before permanent pacemaker therapy is considered. The head‐up tilt test is a useful diagnostic tool for an etiology of paroxysmal AV block.
Pacemaker Interference with Screening Mammography
Authors: ROELKE MARC , RUBINSTEIN VALERIA J. , KAMATH SHUBA , KRAUSER DANIEL , NGARMUKOS TACHAPONG , PARSONNET VICTOR
Published: July 2006

In female pacemaker recipients undergoing screening mammography, the impact of a pulse generator placed in the pectoral region has yet to be reviewed. We evaluated mammograms from 74 female pacemaker patients aged 40 years and older. The pulse generator obscured a portion of the mammogram in 7 patients (12%). During pacemaker implantation in women, the potential for the pulse generator to interfere with screening mammography should be considered. Baseline mammography should be obtained or reviewed; in high risk patients a nonconventional location for the pulse generator may be appropriate.
Optic Neuropathy Following Amiodarone Therapy
Authors: SREIH ANTOINE G. , SCHOENFELD MARK H. , MARIEB MARK A.
Published: July 2006

Ocular changes during treatment with amiodarone are almost universal but are rarely serious. In this article we describe three patients from a single electrophysiology practice in whom optic neuropathy developed during treatment with amiodarone. All three patients were more than 65 years of age. The doses of amiodarone ranged from 100 to 400 mg/day, and the time intervals between the initiation of the amiodarone therapy and the appearance of first symptoms of optic neuropathy were 5 to 19 months. Two patients had bilateral involvement, and one had only unilateral involvement. Whether this result was due solely to amiodarone therapy, to the underlying poor health of these patients, or to the combination of these two factors is uncertain. These findings prompt us to recommend that all patients who receive amiodarone undergo complete ophthalmologic examinations, including careful evaluation of the ocular fundus regularly during such therapy. No randomized study had been undertaken to determine the true incidence of complications associated with this medication.
Atrial Epicardial Pacing with Long Stimulus to P Wave Interval in a Patient with Arrhythmogenic Right Ventricular Dysplasia Complicated by Right Atrial Thrombosis
Authors: KAZMIERCZAK JAROSLAW , KORNACEWICZ‐JACH ZDZISLAWA , WOJTAROWICZ ANDRZEJ
Published: July 2006

Atrial epicardial pacing with a long stimulus to P wave interval in a patient with arrhythmogenic right ventricular dysplasia complicated by right atrial thrombosis is discussed. Arrhythmogenic right ventricular dysplasia (ARVD) is associated with a high incidence of malignant ventricular arrhythmias. Most patients with ARVD need antiarrhythmic drugs, catheter ablation, or an implantable cardioverter defibrillator. We report a patient with ARVD in whom effective treatment with sotalol caused severe, symptomatic sinus bradycardia requiring permanent pacing. Due to leftward displacement of the right ventricle and the presence of two thrombi in the right atrium, an epicardial atrial lead and AAI pacemaker were implanted. A long stimulus to P wave interval caused by severe dilatation of the right atrium was recorded. During a 6 months of follow‐up on sotalol treatment there were neither ventricular tachycardia (VT) attacks nor pacing problems.
Dynamic Left Ventricular Arterial Pressure Gradient and Sick Sinus Syndrome with Heterozygous Fabry's Disease Improved Following Implantation of a Dual Chamber Pacemaker
Authors: NAKAYAMA YASUNORI , TSUMURA KEI , YAMASHITA NAOTOSHI , YOSHIMARU KIYOMICHI
Published: July 2006

A 63‐year‐old woman with heterozygous Fabry's disease, sick sinus syndrome, sinus pauses, congestive heart failure, syncope, and a dynamic pressure gradient between the left ventricle and systemic arteries underwent implantation of a dual chamber (DDD) pacemaker. Following pacemaker implantation, the pressure gradient has been reduced and congestive heart failure controlled for the past 3 years.
Normal Sinus Rhythm in a Patient with Corrected Transposition of Great Arteries After 30 Years of Complete Heart Block
Authors: NGARMUKOS TACHAPONG , WERRES ROLAND
Published: July 2006

A case of a patient with corrected transposition of great arteries with complete atrioventricular block for 29 years who was in sinus rhythm.
A Prospective, Randomized, Comparison in Patients Between a Pectoral Unipolar Defibrillation System and That Using an Additional Inferior Vena Cava Electrode
Authors: FAVALE STEFANO , DICANDIA COSIMO DAMIANO , TUNZI PASQUALE , RIZZON PAOLO
Published: July 2006

The decrease of defibrillation energy requirement would render the currently available transvenous defibrillator more effective and favor the device miniaturization process and the increase of longevity. The unipolar defibrillation systems using a single RV electrode and the pectoral pulse generator titanium shell (CAN) proved to be very efficient. The addition of a third defibrillating electrode in the coronary sinus did not prove to offer advantages and in the superior vena cava showed only a slight reduction of the defibrillation threshold (DFT). The purpose of this study was to determine whether the defibrillation efficacy of the single lead unipolar transvenous system could be improved by adding an electrode in the inferior vena cava (IVC). In 17 patients, we prospectively and randomly compared the DFT obtained with a single lead unipolar system with the DFT obtained using an additional of an IVC lead. The RV electrode, Medtronic 6936, was used as anode (first phase of biphasic) in both configurations. A 108 cm2 surface CAN, Medtronic 7219/7220 C, was inserted in a left submuscular infraclavicular pocket and used as cathode, alone or in combination with IVC, Medtronic 6933. The superior edge of the IVC coil was positioned 2–3 cm below the right atrium‐IVC junction. Thus, using biphasic 65% tilt pulses generated by a 120 μF external defibrillator, Medtronic D.I.S.D. 5358 CL, the RV‐CAN DFT was compared with that obtained with the RV—CAN plus IVC configuration. Mean energy DFTs were 7.8 ± 3.6 and 4.8 ± 1.7 J (P < 0.0001) and mean impedance 65.8 ± 13 O and 43.1 ± 5.5 O (P < 0.0001) with the RV‐CAN and the IVC configuration, respectively. The addition of IVC significantly reduces the DFT of a single lead active CAN pectoral pulse generator. The clinical use of this biphasic and dual pathway configuration may be considered in patients not meeting implant criteria with the single lead or the dual lead RV‐superior vena cava systems. This configuration may also prove helpful in the use of very small, low output ICDs, where the clinical impact of ICD generator size, longevity, and related cost may offset the problems of dual lead systems.
Correlation Waveform Analysis to Discriminate Monomorphic Ventricular Tachycardia from Sinus Rhythm Using Stored Electrograms from Implantable Defibrillators
Authors: MICHAUD GREGORY F. , LI QUAN , COSTEAS XENOPHON , STEARNS ROBERT , III MARK ESTES , WANG PAUL J.
Published: July 2006

In order to examine whether a template‐matching program utilizing correlation waveform analysis (CWA) might be used to discriminate monomorphic ventricular tachycardia (MMVT) from sinus rhythm (SR) in patients with implantable cardioverter defibrillators (ICDs), we studied stored episodes of induced MMVT in 25 patients and compared them to corresponding stored SR electrograms. We calculated mean correlation coefficients for SR beats against an SR template chosen within each sinus episode, induced MMVT beats against an induced MMVT template within each ventricular tachycardia episode, and induced MMVT beats against the original SR template. For each patient, the 99.5% lower confidence limit for the mean correlation coefficient of SR beats versus an SR template (patient‐specific method) or the empirical correlation coefficient value 0.9 were selected as threshold values to discriminate induced MMVT from SR. The mean correlation coefficient for induced MMVT beats versus the original SR template for each patient was subtracted from both threshold values. A positive value is defined as accurate discrimination of induced MMVT from SR. Using 0.9 for a threshold cut off, 21 of 25 episodes of induced MMVT were accurately labeled with a sensitivity of 84%. Using the patient‐specific method, we were able to correctly distinguish 23 of 25 episodes of induced MMVT from SR with a sensitivity of 92%. There was no statistically significant difference between the patient‐specific or empirical methods in detecting MMVT (P 5 0.4). This is the first demonstration using stored intracardiac electrograms from ICDs that CWA is able to discriminate MMVT from SR with high sensitivity. Such a template‐matching system may be used for off‐line analysis or real‐time rhythm discrimination.
Evaluation of Autonomic Influences on QT Dispersion Using the Head‐Up Tilt Test in Healthy Subjects
Authors: NAKAGAWA MIKIKO , TAKAHASHI NAOHIKO , IWAO TETSU , YONEMOCHI HIDETOSHI , OOIE TATS±HIKO , HARA MASAHIDE , SAIKAWA TETSUNORI , ITO MORIO
Published: July 2006

Our objective was to examine the autonomic influence on QT interval dispersion using the head‐up tilt test in healthy subjects. RR and QT intervals, heart rate variability, and plasma norepinephrine concentration were measured in the supine position and tilting to 70± for 20 minutes using a footboard support in 15 healthy male volunteers (mean age ± SD: 28.0 ± 4.5 years). The rate‐corrected QT interval (QTc) was calculated using Bazett's formula, and QT and QTc dispersions were defined as the maximum minus minimum values for the QT and QTc, respectively, from the 12‐lead ECG. Spectral analysis of the heart rate variability generated values for the low‐ and high‐frequency powers (LF and HF) and their ratio (LF/HF). Compared with values obtained in the supine position, tilting significantly increased QT (P < 0.05) and QTc dispersion (P < 0.01), the LF/HF ratio (P < 0.0001), and plasma norepinephrine concentration (P < 0.0001), and significantly decreased HF (P < 0.0001). QTc dispersion was positively correlated with the LF/HF ratio and plasma norepinephrine concentration, and negatively correlated with HF. These results suggest that head‐up tilt testing increases QT dispersion by increasing sympathetic tone and/or decreasing vagal tone in healthy subjects.
Time Trends in the Intracardiac Potential Recorded by Pacemaker Telemetry: Comparison Between Steroid‐Eluting Small Area Electrodes
Authors: BERNASCONI M. , MAESTRI R. , MARZEGALLI M. , PINNA G.D. , GUENZATI G. , FIORISTA F.
Published: July 2006

We assessed the time course of electrograms sensed both in the atrium and ventricle by two different steroid‐eluting electrodes: Medtronic Capsure SP (with an area of 5.5 mm2) and Z (with an area of 1.2 mm2). We considered 68 unipolar electrodes: 31 atrial (19 Capsure SP 4523 and 12 Capsure Z 4533) and 37 ventricular (24 Capsure SP 4023 and 13 Capsure Z 4033) implanted in 47 consecutive patients (30 men and 17 women, with an age of 72 ± 9.4 years). The pacemaker model was Medtronic Elite 7077–7086 (DDD‐DDDR) in 25 patients and Medtronic Legend 8419–8424 (VVIR‐AAIR) in 22 patients. The endocavitary signal (all patients had spontaneous rhythm) was telemetrically obtained by a Medtronic 9790 device and acquired on a personal computer at implantation and 7, 30, and 180 days thereafter. The signal was studied both in the time domain and in the frequency domain by spectral analysis. The following parameters were calculated: amplitude (A): peak‐to‐peak value of the complex; slew rate (SR) peak negative first derivative; F0: frequency at which the power spectrum reaches its maximum value; and bandwidth (Bw): expressed as the distance between the –3 dB points and statistically analyzed by a two‐way analysis of variance with factors “time” (four measurements) and “electrode” (Capsure SP and Z) and repeated measurements on the former. Ventricular sensing: no time or electrode effect (P>0.1 in all comparisons) was found for F0, Bw, or SR, while a time effect (P < 0.04) not dependent on the type of electrode was found for the amplitude of the signal. In particular, a significant increase was found between the measurement at 6 months and that at implantation (P < 0.004). Atrial sensing: A, F0, and bandwidth were not affected by time or electrode (P > 0.09), while SR behaved differently over time (P < 0.05) in the two electrodes (the Capsure Z showed an increase at sixth month [P < 0.04] compared to implantation). In conclusion, the Medtronic Capsure SP and Z electrodes proved to be valid and substantially equivalent as far as concerns the measurement of the intracardiac potential despite the difference between their surface areas. Further studies should be devised to assess whether transitory decreases of atrial Bw in the first month of follow‐up observed in a few patients for both electrodes could be responsible for clinical episodes of sensing deficit.
Head‐Up Tilt Test in Patients with High Pretest Likelihood of Neurally Mediated Syncope: An Approximation to the “Real Sensitivity” of this Testing
Authors: PÉREZ‐PAREDES MATÍAS , PICÓ‐ARACIL FRANCISCO , FLORENCIANO RAFAEL , SÁNCHEZ‐VILLANUEVA JOSÉ G. , ANTONIO RUIZ ROS JOSÉ , RUIPÉREZ JUAN A.
Published: July 2006

This study was designed to examine the “true sensitivity” of a specific head‐up tilt (HUT) testing protocol using clinical findings. The HUT protocol used 45 minutes at 60± for the baseline portion and intermittent boluses of 2, 4, and 6 μg of isoproterenol in the second phase. Eighty‐eight patients (40 men and 48 women; mean age of 33.8 ± 16 years) with recurrent syncope and high pretest likelihood of neurally mediated syncope were included. The following were considerated as high pretest likelihood criteria: (1) at least two syncopal episodes; (2) no structural heart disease and normal baseline ECG; (3) age < 65 years; (4) a typical history of neurally mediated syncope, triggering factors plus premonitory signs; and (5) short duration of symptoms and fast recovery without neurological sequelae. Fifty‐four patients (61%) had a positive tilt test (34/88 baseline [39%] and 20/50 with isoproterenol [40%]). The shorter time interval between the last syncopal episode and baseline HUT test was the only predictor for a positive response (P < 0.003). Conversely, this time interval was not predictor of positive responses during isoproterenol‐tilt testing. In conclusion: (1) we claim a “sensitivity” for this combined protocol of 61%; and (2) our results indicate that patients with syncope of unknown origin must be tilted nearest as possible to the last syncope to increase the positive responses of HUT test.