bluuebunny/crossref_metadata_2025 huggingface dataset:
Adjustable Atrial and Ventricular Temporary Electrode for Low‐Energy Termination of Tachyarrhythmias Early After Cardiac Surgery
Authors: MEHMANESH HORMOZ , BAUERNSCHMITT ROBERT , LANGE RÜDIGER , HAGL SIEGFRIED
Published: July 2006

Supraventricular and ventricular tachycardias are common and serious postoperative complications early after cardiac surgery. We introduce a completely removable temporary adjustable defibrillation electrode (TADE) for low energy cardioversion/defibrillation of postoperative atrial and ventricular tachyarrhythmias. The electrode consists of three loops of steel wires connected to one steel wire, which are movable within an isolation sheet for adjusting the active surface to the individual size of the heart chambers. Evaluation of the electrode was performed in 10 open‐chest beagles with a mean weight of 25.5 kg. The electrodes were first positioned on the left and right atrium. Atrial fibrillation (AF) was induced via a bipolar temporary heart wire. Atrial defibrillation thresholds (DFTs) were measured according to a step‐down shock protocol (5–0.4 J). Thereafter, the electrodes were adjusted and positioned on the right and left ventricle. Ventricular fibrillation (VF) was induced and DFTs were recorded the same way. Aortic flow and pressure and left ventricular pressure were continuously monitored throughout the experiment. For termination of AF, mean DFTs were 0.4 ± 0 J (lowest possible shock level) with a mean shock impedance of 70 ± 7.6 Ω. VF was terminated with a mean DFT of 3 ± 1.1 J with a mean impedance 56.1 ± 7.9 Ω. Complete transcutaneous removal of the electrodes was possible in all animals without any complications. In conclusion, successful low energy termination of AF and VF is possible with the tested temporary adjustable electrode. A clinical study is planned for further evaluation.
Percutaneous Transcatheter Repositioning of Displaced Permanent Pacemaker Lead
Authors: FAVALE STEFANO , NACCI FRIDA
Published: July 2006

In three patients, two with a pacemaker and one with an implantable cardioverter defibrillator, hospitalized for dislodgement of a passive fixation J‐shaped atrial lead, a percutaneous transcatheter repositioning was successfully attempted thus avoiding surgical revision. This procedure, performed through the femoral vein, is easy and safe. The stability of the lead position and of the pacing and sensing parameters was confirmed 1 and 6 months after the transcatheter repositioning.
Analysis of Charges and Complications of Permanent Pacemaker Implantation in the Cardiac Catheterization Laboratory Versus the Operating Room
Authors: YAMAMURA KENNETH H. , KLOOSTERMAN E.MARTIN , ALBA JULIA , GARCIA FREDDY , WILLIAMS PATRICIA LOVE , MITRAN RAUL D. , INTERIAN ALBERTO
Published: July 2006

During the last two decades, an increasing number of permanent pacemakers have been implanted outside of the operating room (OR) by nonsurgeons. Previous investigators have demonstrated that pacemakers can be safely implanted in the cardiac catheterization laboratory with no increase in complications or infections. This is the first study of its kind to simultaneously evaluate cost, length of hospitalization, and complications between pacemakers implanted in the OR by surgeons with those implanted in the catheterization laboratory by an electrophysiologist. A total of 254 consecutive pacemaker implants were analyzed over a 2‐year period. The OR group consisted of 122 patients with a mean age of 64 ± 21 years versus 132 patients in the catheterization laboratory group with a mean age of 65 ± 17 years. The indication and type of pacemaker implanted were similar among both groups with 78% of OR patients and 73% of catheterization laboratory patients receiving dual chamber devices. The average cost for pacemaker implantation in our study was significantly higher in the OR group $5,464 ±$1,670 versus $2,682 ±$8 for the catheterization laboratory group (P < 0.001). There was a reduction in preimplant days in the catheterization laboratory group 3.16 ± 12.40 days versus 5.65 ± 9.54 days in the OR group (P < 0.05). Complications were minimal and there were no significant differences between the two groups. This study confirms that pacemakers can be safely implanted in the catheterization laboratory by nonsurgeons with no increase in complications and a significant reduction in hospital costs.
Affective Distress and Implantable Cardioverter Defibrillators: Cases for Psychological and Behavioral Interventions
Authors: SEARS SAMUEL F. , CONTI JAMIE B , CURTIS ANNE B , SAIA TARA L , FOOTE REBECCA , WEN FRANCIS
Published: July 2006

The implantable cardioverter defibrillator (ICD) may be associated with some degree of psychological maladjustment, especially in patients experiencing high rates of discharge. This article reviews the psychological literature related to ICDs and presents two case examples illustrating common psychological complications related to multiple discharges. A brief, psychological intervention can be implemented to improve patient adjustment. To explain possible processes by which psychological complications may develop in ICD patients, two well‐established psychological theories of learning and behavior, classical conditioning and learned helplessness, are reviewed. Multidisciplinary teams that include consultation with clinical psychologists are suggested for the routine care of ICD patients.
Evaluation of Appropriate Pacing with Myocardial Perfusion and Cardiac Function as a Treatment of End‐Stage Idiopathic Dilated Cardiomyopathy
Authors: WATANABE TAKUYA , OKAZAKI OSAMU , IZUMO KAZUHIDE , AKUTSU YASUSHI , KATAGIRI TAKASHI , HARUMI KENICHI
Published: July 2006

We sought to determine an appropriate pacing mode on the basis of myocardial perfusion and cardiac function as assessed by nitrogen‐13 ammonia positron emission tomography in a patient with end‐stage idiopathic dilated cardiomyopathy.
Modification of Antegrade Slow Pathway is not Crucial for Successful Catheter Ablation of Common Atrioventricular Nodal Reentrant Tachycardia
Authors: GIANFRANCHI LORELLA , BRIGNOLE MICHELE , DELISE PIETRO , MENOZZI CARLO , PAPARELLA NELLY , THEMISTOCLAKIS SAKIS , BONSO ALDO , LOLLI GINO , ALBONI PAOLO
Published: July 2006

We tested the hypothesis that in some patients affected by typical AVNRT, successful catheter ablation treatment may be achieved independently of specific measurable electrophysiological modifications of antegrade AV node conducting properties. Standard electrophysiological parameters and comparable antegrade AV node function curves were obtained, before and after successful ablation, in 104 patients (mean age 52 ± 16 years; 69 women and 35 men) affected by the common form of AVNRT. The end point of the ablation procedure was noninducibility of AVNRT and of no more than one echo beat. For the purpose of this study, AV node duality was defined as an increase of ≥ 50 ms in the A2H2 interval in response to a 10 ms decrease of the A1A2 coupling interval. Before ablation, AV node duality was present in 65 patients (62%) and absent in 39 patients (37%). Ablation caused measurable modifications of electrophysiological properties of the AV node in most patients with elicited AV node duality, but not in most patients without demonstrable AV node duality. After ablation, AV node duality persisted in 20 patients who had it before, whereas a new duality that could not be elicited before appeared in 5 patients. During 19 ± 6 months of follow‐up, clinical AVNRT recurred in 1 of 45 patients who had disappearance of AV node duality after ablation, in 1 of 34 patients who did not show AV node duality before and after ablation, and in 1 of 20 patients who had persistence of AV node duality after ablation. In conclusion, modifications of antegrade conduction properties of the AV node are not crucial for the cure of AVNRT in many patients.
Isoproterenol Induced Cardiovascular Hypersensitiviy in Nonpheochromocytoma Patients with Paroxysmal Hyperadrenergic Symptoms
Authors: YAMANOUCHI YOSHIO , WINKELMAN EUGENE , PASHKOW FREDRIC J. , FOUAD‐TARAZI FETNAT M.
Published: July 2006

The objective of this study was to determine whether graded isoproterenol infusion test identifies a specific hypersensitivity response of the LV diastolic relaxation properties in nonpheochromocytoma patients with paroxysmal symptoms of hyperadrenergic surges. We hypothesized that patients with hyperadrenergic surges, not due to pheochromocytoma, have hypersensitivity of cardiac β‐adrenergic receptor responses to exogenous catecholamines, resulting in enhancement of LV relaxation. We assessed the physiological β1 and β2 receptor responsiveness to graded isoproterenol infusion (0.01, 0.02, 0.03 and 0.04 μg/kg per min) in 32 patients presented with hyperadrenergic surges not due to pheochromocytoma. Two major observations were made. First, systemic hemodynamic evaluation using 99m Technetium first pass method revealed hyperkinetic state only in 21 patients (20 females and 1 male; aged 31 ± 9 years); the other 11 patients were without hyperkinetic circulatory state (10 females and 1 male; aged 41 ± 9 years). At baseline, plasma catecholamines were not significantly different between the two groups. The baseline corrected LV peak filling and ejection rates (cPFR and cPER) were significantly higher in hyperkinetic group (cPFR: 10 ± 2 vs 8 × 2 ± 10‐2 Hz/ms, P = 0.03; cPER: 11 ± 2 vs 8 ± 1 × 10‐2 Hz/ms, P = 0.002) and their baseline HR was faster (85 ± 16 vs 70 ± 9 beats/min, P = 0.006). Second, the cardiac and vascular responses to isoproterenol infusion were compared between these two groups. During the graded isoproterenol infusion, the response of HR, systolic, and diastolic BP were not significantly different between the two groups at all doses of isoproterenol, but cPFR and cPER had a more marked response to the lowest dose of 0.01 mg/kg per min in the hyperkinetic group. Thus, the graded isoproterenol infusion test can differentiate between two groups of non‐pheochromocytoma patients presenting with paroxysmal symptoms of hyperadrenergic surges. Only patients with baseline hyperkinetic hemodynamic profile had accentuated cardiac hyperresponsiveness to a low dose of isoproterenol. We concluded that cPFR and cPER is a more sensitive index to assess the response to isoproterenol, because of metabolic determinants affecting the rate of change in LV volume.
Prospective Evaluation of a Two‐Step Therapeutic Strategy in Neurocardiogenic Syncope: Midodrine as Second Line Treatment in Patients Refractory to β‐Blockers
Authors: KLINGENHEBEN THOMAS , CREDNER SUSANNE , HOHNLOSER STEFAN H.
Published: July 2006

Pharmacological therapy of neurocardiogenic syncope is often limited by the relatively low response rate to such treatment. In particular, response to β‐blocker treatment has been reported to average 50%. Therefore, two‐step protocol, with metoprolol being the drug of first choice, was developed and prospectively evaluated in consecutive patients with a history of repeated syncopal attacks and a positive tilt table test indicative of neurocardiogenic syncope. Patients not responding to the β‐blocker were switched to the α‐adrenoceptoragonist midodrine. Acute drug efficacy was assessed by repeated tilt table testing. The incidence of syncope recurrence rate was determined during a 7‐month follow‐up. In 16 of 30 (53%) patients, metoprolol was primarily effective; this was also the case in 7 of 11 patients receiving midodrine. Thus, the overall efficacy rate could be increased to 77% by the treatment protocol (P = 0.009, as compared to β‐blocker treatment alone). During follow‐up, only 1 of 27 patients (4%) had a syncopal event. Thus, the two‐step treatment protocol presented in this study proved to be safe and to improve significantly patients clinical symptoms, as well as results of repeated tilt table testing as compared to β‐blocker treatment alone.
Plasma Brain Natriuretic Peptide as a Biochemical Marker for Atrioventricular Sequence in Patients with Pacemakers
Authors: HORIE HAJIME , TSUTAMOTO TAKAYOSHI , ISHIMOTO NAOKO , MINAI KAZUO , YOKOHAMA HIROSHI , NOZAWA MASATO , IZUMI MASAFUMI , TAKAOKA ATSUSHI , FUJITA TAMOTSU , SAKAMOTO TAIZO , KITO OSAMU , OKAMURA HIROSHI , KINOSHITA MASAHIKO
Published: July 2006

We hypothesized that plasma brain natriuretic peptide, like plasma atrial natriuretic peptide, may reflect hemodynamic changes elicited by different cardiac pacing modes. The aim of this study was to investigate whether plasma brain natriuretic peptide could be influenced by different pacing modes or electrical stimulation. The subjects consisted of 164 patients with permanent pacemakers (52 VVI, 30 AAI, 82 DDD pacemakers) and unimpaired heart function. Patients with atrial fibrillation or spontaneous beats were excluded. Plasma atrial natriuretic peptide and brain natriuretic peptide levels were measured at a rate of 70 beats/min after 45 minutes in the supine position. Under ECG monitoring, the pacing mode was switched from DDD to VVI in 12 patients and from DDD to AAI in 4 patients with a dual chamber pacemaker. Plasma atrial natriuretic peptide and brain natriuretic peptide levels were also measured 30 minutes, 60 minutes, and 1 week after mode switching. Plasma atrial natriuretic peptide and brain natriuretic peptide levels were significantly higher in the nonphysiological pacing group than in the physiological pacing group, whereas these values were similar in the DDD and AAI pacing groups. One week after switching from DDD to VVI, plasma atrial natriuretic peptide and brain natriuretic peptide levels were significantly increased, however no significant changes were observed after switching to AAI. Based on a multivariate regression analysis of noninvasive clinical parameters, only a low plasma brain natriuretic peptide was significantly correlated with physiological pacing. We conclude that: (1) plasma brain natriuretic peptide, like atrial natriuretic peptide, is influenced by the pacing mode, but is not influenced by electrical stimulation; and (2) low plasma brain natriuretic peptide is important in relation to physiological pacing.
Rate Dependent Effects of Procainamide on the Threshold Current for Pacing in the Setting of Postrepolarization Refractoriness in Dogs
Authors: LEERSSEN HENDRIK M. , VOS MARC A. , DEN DULK KAREL , VAN DER ZANDE JOLANDA , WELLENS HEIN J.
Published: July 2006

Normally, ventricular APD exceeds the VERP. However, under specific circumstances this relation may change and can become inverse. This phenomenon of postrepolarization refractoriness may be caused by a decrease in excitability. The threshold current (TC) for pacing has never been quantified as a possible explanation for these observations. Using a MAP pacing catheter in the right ventricular apex, the rate dependent behavior of TC, VERP, and APD before and after procainamide (dose 20 mg/kg in 10 min + 5 mg/min infusion) was determined in 17 dogs with chronic complete AV block. Initially, TC was determined with 0.1 mA accuracy. Using a pacing current of at least twice TC, VERP and APD showed a similar, rate dependent shortening for PCLs 800, 575, and 350 ms. Procainamide treatment led to an equal, rate independent VERP and APD increase: no post repolarization refractoriness. Subsequently, accuracy for TC determination was increased to 0.01 mA. Comparing PCLs 800 and 250 ms, TC doubled from 0.05 ± 0.01 to 0.10 ± 0.09 mA during control and almost tripled from 0.06 ± 0.02 to 0.17 ± 0.10 mA (P < 0.05) after procainamide. Using a fixed pacing current of exactly twice TC found at 800 ms PCL during control, VERP exceeded APD after procainamide treatment at 300 and 250 ms PCL: postrepolarization refractoriness. Increasing the pacing current to twice the rate dependent TC, the relation between VERP and APD normalized: no postrepolarization refractoriness. We conclude that after procainamide, rate dependent TC increase is of major importance for the phenomenon of postrepolarization refractoriness.
Efficacy and Safety of Clonazepam in Refractory Neurally Mediated Syncope
Authors: KADRI NAZIH N. , HEE TOM T. , ROVANG KAREN S. , MOHIUDDIN SYED M. , RYAN TIMOTHY , ASHRAF RAASHID , HUEBERT VINCENT , HILLEMAN DANIEL E.
Published: July 2006

Neurally mediated syncope is a complex syndrome that is often difficult to manage using currently available treatment strategies. The efficacy and safety of clonazepam was evaluated in 35 patients with refractory neurally mediated syncope. All patients had syncope (n=33) or disabling presyncope (n=2) and a positive head‐up tilt table test (HUTT) despite treatment with one or more of the following therapies: β‐blocker, high‐salt diet, fludrocortisone, elastic compression stockings, and disopyramide. Clonazepam was initiated at 0.5 mg/day and titrated in 0.25–0.5 mg/day increments for symptom control. Early (first 8 weeks) symptomatic response was achieved in 31 of 35 (89%) patients. Early HUTT reverted to negative in 29 of 35 (83%) patients. Two patients discontinued clonazepam during early follow‐up due to side effects. Thirty‐three patients received long‐term clonazepam therapy. Twenty‐five patients had late HUTT with 21 remaining negative. Of the eight patients who did not have late HUTT, one patient discontinued clonazepam prior to HUTT due to side effects. Seven patients refused late HUTT. All seven patients achieved symptomatic control on clonazepam with two requiring dose titration. Of the 21 patients with a negative late HUTT, 18 achieved symptomatic control with two of these patients requiring dose titration. Two patients who had only partial symptom control despite dose titration achieved total symptomatic control with the addition of disopyramide and β‐blockers. Two patients with a negative late HUTT discontinued clonazepam due to side effects. One patient had been symptomatically controlled while the other had recurrent symptoms with dose limiting side effects occurring after clonazepam dose titration. In the 4 patients with a positive late HUTT, 2 patients were symptomatically controlled, 1 patient required combination therapy with a β‐blocker to achieve symptomatic control, and 1 patient discontinued therapy due to side effects. Overall, 29 of 35 (83%) patients continue to receive clonazepam with symptom control. Based on intention‐to‐treat HUTT results, 21 of 35 (60%) patients were responders. Four patients required clonazepam dose titration and three required combination therapy with clonazepam plus disopyramide and/or a β‐blocker to achieve control. Clonazepam was discontinued in 6 patients. 5 for side effects and 1 following a transient ischemic attack. Clonazepam appears to be an effective therapeutic alternative in patients with refractory neurally mediated syncope. Based on our preliminary findings, a placebo controlled evaluation of clonazepam in neurally mediated syncope is warranted.
Performance of Temporary Epicardial Stainless Steel Wire Electrodes Used to Treat Atrial Fibrillation: A Study in Patients Following Open Heart Surgery
Authors: LIEBOLD ANDREAS , RÖDIG GABRIELE , BIRNBAUM DIETRICH E.
Published: July 2006

AF is the most common arrhythmia following open heart surgery. Transthoracic cardioversion is used when pharmacological treatment fails to restore SR, or is ineffective in controlling ventricular response rate. We report on the performance of temporary atrial defibrillation wire electrodes implanted on the epicardium of patients undergoing open heart surgery. Epicardial stainless steel wire electrodes for both pacing/sensing and atrial defibrillation were placed at the left and right atrium during open heart surgery in 100 consecutive patients (age 65 ± 9 years; male/female 77/23). Electrophysiological studies performed postoperatively revealed a test shock (0.3 J) impedance of 96 ± 12 Ω (monophasic) and 97 ± 13 Ω (biphasic). AF was induced by burst stimulation in 84 patients. All patients were successfully converted to SR. The mean energy of successful shocks was 3.1 ± 1.9 J. Atrial pacing and sensing were accomplished in all patients. Pacing threshold was 1.9 ± 1.7 V (0.5 ms) in the left atrium and 2.1 ± 2 V in the right atrium. P wave sensing was 2.5 ± 1.6mV in the left atrium and 2.3 ± 1.4 mV in the right atrium. No complications were observed with shock application, nor with lead extraction. Atrial defibrillation using temporary epicardial wire electrodes can be performed successfully and safely in patients following cardiac operations. The shock energy required to restore SR is low. Electrical cardioversion in the absence of anesthesia should be feasible.
QT Dispersion in Children With Ventricular Arrhythmia and a Structurally Normal Heart
Authors: WALLER B. RUSH , BALAJI SESHADRI , YE XIAOBU , GILLETTE PAUL C.
Published: July 2006

In adults, increased QT dispersion has been shown to predict arrhythmic risk as well as risk of sudden death in several clinical settings. It is not known whether or not QT dispersion is increased in children with idiopathic ventricular arrhythmia. We studied three groups of children: (1) 20 patients with idiopathic VT (aged 3–18 years; mean 11.2 years); (2) 30 patients with benign PVCs (aged 1–20 years; mean 10.5 years); and (3) 30 control subjects (aged 4–17 years; mean 12 years). Standard ECGs were reviewed and the dispersion of both QT and JT intervals was compared. No patient had structural heart disease or long QT syndrome. The QT and QTc dispersion (QTΔ, QTcΔ) among the three groups did not differ: QTcΔ of the VT group was 70 ms ± 30 ms, QTcΔ of PVC patients was 60 ms ± 30 ms, and the QTcΔ of the control group was 65 ms ± 30 ms. The JTcΔ among the three groups did not differ as well: JTcΔ of the VT group was 70 ms ± 30 ms, the JTcΔ of the PVC group was 60 msec ± 25 msec, and the JTcΔ of the control group was 70 ms ± 30 ms. We conclude that QT and JT dispersion are not significantly altered in children with idiopathic VT or benign PVCs when compared to control subjects. QT dispersion is not a reliable marker for arrhythmic risk in children with idiopathic ventricular arrhythmias and structurally normal hearts.
Impaired Cardiac Performance Relating to Delayed Left Atrial Activation after Atrial Compartment Operation for Chronic Atrial Fibrillation
Authors: LO HUEY‐MING , LIN FANG‐YUE , LIN JIUNN‐LEE , HSU KUAN‐LIH , CHIANG FU‐TIEN , TSENG CHUEN‐DEN , TSENG YUNG‐ZU
Published: July 2006

In the presence of a normal atrial systole and optimal AV delay, atrial kick contributes to a significant fraction of the stroke volume. This atrial contribution may be lost during atrial asystole or mismatch in the timing of atrial and ventricular contraction. A patient received atrial compartment operation for his chronic AF. Although the AF was successfully converted to sinus rhythm, the conduction from the right to left atrium was markedly delayed so that the left atrial and ventricular activations occurred almost simultaneously. This delay in left atrial activation resulted in impaired cardiac performance.
Atypical AV Nodal Reentry with Bystander Accessory Pathway: An Unusual Mechanism of Preexcited Tachycardia
Authors: GLIKSON MICHAEL , BELHASSEN BERNARD , ELDAR MICHAEL
Published: July 2006

We present an unusual mechanism of preexcited tachycardia—atypical AV nodal reentry with bystander AP. It can be differentiated from other preexcited tachycardias by its variable degree of preexcitation (either spontaneous or in response to atrial pacing), higher degree of preexcitation with pacing near the origin of the AP than during tachycardia, inability to preexicite the tachycardia by either late atrial or ventricular premature beats, the presence of nonpreexcited atypical AV nodal reentry tachycardia following successful AP ablation, and by exclusion of atrial tachycardia.
Predominant Tricuspid Stenosis Secondary to Bacterial Endocarditis in a Patient With Permanent Pacemaker and Balloon Dilatation of the Stenosis
Authors: NISANCI YILMAZ , YILMAZ ERCUMENT , ONCUL AYTAC , OZSARUHAN ONAL
Published: July 2006

In a 49‐year‐old woman with sick sinus syndrome and a pemanent VVI pacemaker, severe tricuspid stenosis and its clinical consequences developed 4 years after the attack of endocarditis. Besides the quite unusual occurrence of lead related tricuspid stenosis, successful treatment with balloon dilatation is the unique feature of this case.
Long‐Term Survival After Permanent Pacemaker Implantation in Young Adults: 30 Year Experience
Authors: MAYOSI BONGANI M. , LITTLE FRANCESCA , MILLAR ROBERT N. SCOTT
Published: July 2006

The goal of the present study was to determine the etiology of conduction disease and long‐term outcome for young adults who undergo permanent pacemaker implantation. Permanent pacing was performed in 232 patients aged 21–50 years, 135 males and 97 females, from 1965 through 1995. One hundred and twenty‐six subjects (54%) had evidence of structural heart disease, while idiopathic conduction disease accounted for 46%. About half (54%) of 106 patients with structural heart disease had surgically induced heart block. Pacing mode at primary implantation was single chamber in 65% and dual chamber in 35%. Follow‐up ranged from 12–387 months, with a mean of 104–months. At the last follow‐up, 133 of 232 patients (57%) were alive, 40 (17%) had died, 30 (13%) were lost to follow‐up, 26 (11%) were transferred elsewhere, and 3 (1%) explanted. Patients with sick sinus syndrome had similar outcomes to those with AV block. There was a sharp decline in survival during the first six months; 7.5% of the sample died within the first year following their first pacemaker operation. After the first year, the decline in survival slowed and 70% of the patients could be expected to survive beyond 20 years. The overall survival of young patients without structural heart disease who received a permanent pacemaker was comparable to an age‐ and sex‐matched control population, while patients with structural heart disease performed significantly worse than the control population.
Catheter Tip Orientation Affects Radiofrequency Ablation Lesion Size in the Canine Left Ventricle
Authors: CHUGH SUMEET S. , CHAN RODRIGO C. , JOHNSON SUSAN B. , PACKER DOUGLAS L.
Published: July 2006

While some factors influencing size of RF lesions in ventricular tissue have been characterized, the effects of catheter electrode‐endocardial surface orientation on lesion generation have not been investigated. Therefore, the effects of parallel versus perpendicular catheter electrode‐endocardial surface orientation on dimensions of RF lesion produced with 4‐, 6‐, 8‐, 10‐, and 12‐mm distal electrode lengths were studied in 20 closed‐chested dogs. Orientation was established by biplane fluoroscopy and confirmed by intracardiac echocardiography for the majority of energy deliveries (71%). RF voltage was titrated to maintain constant catheter electrode temperature of 75°C for 60 seconds. In the perpendicular orientation, lesion size did not change significantly with increasing electrode lengths. There was a statistically significant interaction between electrode orientation and maximum lesion length (analysis of variance [ANOVA] P = 0.04), lesion width (ANOVA P = 0.01), lesion area (ANOVA P = 0.02), and estimated lesion volume (ANOVA P < 0.005) over all electrode lengths. With parallel tip‐tissue orientation, lesion size was a function of increasing electrode length. For 4‐, 6‐, 8‐, 10‐, and 12‐mm electrodes, maximum lesion surface areas were 95 ± 38, 97 ± 38, 119 ± 29, 147 ± 52, and 147 ± 67 mm2, respectively. For electrode lengths 8, 10. and 12 mm, estimated lesion volumes were significantly greater with parallel orientation (P < 0.05 for all). Thus, ventricular lesion size is dependent on catheter electrode length, but only when the catheter is oriented parallel to the endocardial surface. This information may be helpful in increasing lesion dimensions for RF ablation of ventricular tachycardias.
The Utility of Quantitative Body Surface Isoarea Mapping for Predicting Ventricular Tachyarrhythmias
Authors: GOLDNER BRUCE G. , HORWITZ LEORA , KOHN NINA , LESSER MARTIN , EHRLICH JASON , COHEN TODD J. , JADONATH RAM
Published: July 2006

Noninvasive techniques, such as the signal averaged ECG, have been used to assess risk of ventricular tachyarrhythmias (VT). However, these methods produce false positive and negative results. The purpose of this study was to develop body surface map algorithms which would enhance prediction of susceptibility to VT. Fifty‐three patients referred for programmed electrical stimulation were enrolled in this study. All patients underwent signal averaged ECG, body surface map, programmed electrical stimulation. Group I patients had no sustained inducible VT and group II patients had either inducible sustained VT at electrophysiology study or previously documented spontaneous, sustained VT. For body surface map analysis, the difference between extrema on isoarea maps was calculated and defined as the gradient range. An abnormal body surface map was defined as a QRST gradient range ≤ 109 mv.ms. The mean QRST gradient range in group II was significantly < that in group I (P < 0.05). By logistic regression analysis, the presence of coronary artery disease, a QRST gradient range ≤ 109 mv.ms, an EF < 40% and a singal averaged ECG QRS duration > 114 ms predicted VT. The sensitivity, specificity, positive and negative predictive values for predicting VT susceptibility of an algorithm which combines the signal averaged ECG QRS duration and the QRST gradients were 0.93, 0.76, 0.79, and 0.91, respectively, while those for the signal averaged ECG alone were 0.52, 0.69, 0.63, and 0.59 for VT susceptibility. A combined body surface map‐signal averaged ECG algorithm was more sensitive in detecting susceptibility to VT than the signal averaged ECG alone.
A Gastroesophageal Electrode for Electrophysiological Studies
Authors: MCENEANEY DAVID J. , ESCALONA OMAR , ANDERSON JOHN A. , ADGEY A.A. JENNIFER
Published: July 2006

A novel gastroesophageal electrode has been developed capable of atrial and ventricular pacing. We performed electrophysiological studies using the gastroesophageal electrode (Esothoracic) and compared the results with the standard endocardial approach. The flexible polythene gastroesophageal electrode was passed into the stomach under light sedation. Five ring electrodes, now positioned in the lower esophagus were used for bipolar atrial pacing and recording. Ventricular pacing was performed using a cathodic point source on the gastroesophageal electrode tip; the indifferent electrode (anode) was a high impedance chest pad. Parameters of sinus and AV nodal function were obtained by atrial pacing. Programmed ventricular stimulation was performed using a standard protocol. These electrophysiological parameters were subsequently determined using the endocardial approach. There was close correlation between measurements of sinus and AV node function using the two approaches in 48 subjects: sinus node recovery time (SNRT) r2= 0.70, corrected sinus node recovery time (CSNRT) r2= 0.87, AV Wenckebach cycle length (AVWCL) r2= 0.97. The degree of agreement between the two approaches was estimated by the mean difference δ and standard deviation of the difference σ (SNRT δ= 40 ms, σ= 257 ms: CSNRT σ= 14 ms, δ= 164 ms; AVWCL σ= 7 ms, δ= 16 ms). Programmed ventricular stimulation was performed in 15 of 48 subjects with known or suspected ventricular tachyarrhythmias. Seven had ventricular tachycardia induced using both esothoracic and endocardial programmed ventricular stimulation. One subject was noninducible using esothoracic programmed ventricular stimulation, but inducible at endocardial electrophysiological studies. Another subject was inducible at esothoracic electrophysiological studies, but noninducible using endocardial programmed ventricular stimulation. Six subjects were noninducible using both endocardial and esothoracic programmed ventricular stimulation. The gastroesophageal electrode permits reliable atrial and ventricular pacing without transvenous catheterization or fluoroscopy. Electrophysiological parameters determined using this electrode are similar to those obtained using endocardial stimulation.
Characteristics and Radiofrequency Catheter Ablation of Septal Accessory Atrioventricular Pathways
Authors: TAI CHING‐TAI , CHEN SHIH‐ANN , CHIANG CHERN‐EN , CHANG MAU‐SONG
Published: July 2006

Septal accessory AV pathways are located in the complex AV septal space that also contains the specialized conduction system. They have unique electrocardiographical and electrophysiological characteristics to be differentiated from free‐wall accessory pathways. Some of the septal pathways have AV nodelike conduction properties and produce a similar activation sequence in the retrograde conduction. Several methods have been developed to distinguish them from AV nodal pathways. Radiofrequency catheter ablation using the titration method and endocardial approach without entrance into the coronary sinus is effective in eliminating most of the septal accessory pathways without impairment of AV conduction. However, some posteroseptal accessory pathways may require energy application inside the coronary sinus, thus information of the coronary sinus anatomy is important for preventing complication.
The Impact of the Millennium Problem on Implantable Pacemakers and Defibrillators
Authors: DASSEN WILLEM R.M. , DIJK W. ARNOLD , HOOIJSCHUUR CARLA A.M. , MALIK MAREK
Published: July 2006

The unpredictable behavior of computer systems on January 1, 2000, known as the millennium problem or millennium‘bug,’also affects medical establishments and, due to the large use of computers in all kind of applications, cardiological clinics in particular. This review discusses the effect of the millennium computer problem on the implantation procedures and follow‐up registries of implantable pacemakers and defibrillators. The review concludes that the transition in the next millennium will not influence the proper functioning of implanted pacemakers and defibrillators. The function of pacemaker/defibrillator programmers seems to be safe and no major difficulties are anticipated. Pacemaker databases and the logistics linked to the implantation and follow‐up of patients and their pacemaker may and probably will be affected by the millennium transition. Using the FDA database on biomedical equipment, the actual status of all biomedical devices can be assessed.
Failure of Right Atrial Premature Beats to Reset Atriofascicular Tachycardia
Authors: PORKOLAB FREDERICK L. , ALPERT BARRY L. , SCHEINMAN MELVIN M.
Published: July 2006

A patient with a right atriofascicular (Mahaim) tachycardia was found to have inducible antidromic supraventricular tachycardia, but atrial premature beats from the right atrial free wall failed to reset the tachycardia. An interesting transition from AV nodal reentry tachycardia to Mahaim tachycardia is also presented.
Invasive Ductal Carcinoma of the Male Breast Expanding From Pacemaker Pocket Decubitus
Authors: KNEZ IGOR , CERWENKA HERWIG , MOINFAR FARID , HOFF MARTIN , MÄCHLER HEINRICH , ANELLI‐MONTI MICHAEL , RADNER HERBERT , RIGLER BRUNO
Published: July 2006

After twenty‐five Years of therapy with different unifocal pacemaking systems, an 84‐year old male patient developed a nonseptic pacemaker decubitus. A rare incidental finding of invasive ductal carcinoma of the right mammary gland was surgically treated by a generous excision of the tumor and by consecutive modified radical mastectomy. According to published literature, the association of invasive ductal carcinoma arising from a pacemaker pocket decubitus and followed by curative treatment has not been previously reported. We do conclude that pacemaker generators in close relationship to the mammary gland should be considered with suspicion.
Runaway Pacemaker Caused by a Stuck Accelerometer
Authors: NAKAZATO YUJI , NAKATA YASURO , YASUDA MASAYUKI , NAKAZATO KAORU , TANAKA MIKIO , SUMIYOSHI MASATAKA , SAKURAI HIDEHIKO , YAMAGUCHI HIROSHI
Published: July 2006

We report a case of runaway pacemaker with a ventricular pacing rate of 190 beats/min. The runaway occurred when the accelerometer became stuck due to the magnet application during VVIR pacing. Runaways in modern pacemakers are particularly rare, but they do still occur. The best solution for this phenomenon is generator replacement.
Acute Testing of the Rate‐Smoothed Pacing Algorithm for Ventricular Rate Stabilization
Authors: LEE JOHN K. , YEE RAYMOND , BRANEY MARILYN , STOOP GUUS , BEGEMANN MALCOLM , DUNNE CATHERINE , KLEIN GEORGE J. , KRAHN ANDREW D. , VAN HEMEL NORBERT M.
Published: July 2006

We evaluated the capability of a new pacemaker‐based rate‐smoothing algorithm (RSA) to reduce the irregular ventricular response of AF. RSA prevents sudden decreases in rate using a modified physiological band and flywheel feature. Twelve patients (51 ± 21 years) with hemodynamically tolerated AF of 4 months to 20 years duration were studied. Atrial and ventricular leads were connected to the external pacemaker device in the electrophysiology laboratory. Consecutive RR intervals during AF were measured at baseline and after ventricular pacing with RSA ON. Ventricular pacing with the rate smoothing algorithm reduced maximum RR intervals (1,207 ± 299 vs 855 ± 148 ms, P = 0.0005), with no significant change in the minimum RR interval (401 ± 55 vs 393 ± 74 ms, P = 0.292). A small shortening of the mean RR interval (634 ± 153 vs 594 ± 135 ms, P = 0.007) was seen with no change in the median RR interval (609 ± 153 vs 595 ± 143 ms, P = 0.388). There was a 43% reduction in RR standard deviation (145 ± 52 vs 82 ± 28, P = 0.0005), 49% reduction in mean absolute RR interval difference (MAD) (152 ± 64 vs 77 ± 34, P = 0.0005) and MAD/mean RR ratio (0.23 ± 0.05 vs 0.13 ± 0.04, P = 0.0005). We conclude that rate‐smoothed pacing effectively reduces RR variability of AF in the acute setting.
Experimental His‐Bundle Pacing: Histopathological and Electrophysiological Examination
Authors: AMITANI SHIGERU , MIYAHARA KENKICHI , SOHARA HIROSHI , KAKURA HIDEAKI , KOGA MASAAKI , MORIYAMA YUKINORI , TAIRA AKIRA , NAGANO SHIN‐ICHI , MIURA NAOKI , MISUMI KAZUHIRO , SAKAMOTO† HIROSHI
Published: July 2006

His‐bundle pacing gives a more physiological ventricular contraction in comparison to right ventricular apical pacing. However the problems of lead fixation and stability of long‐term His‐bundle pacing are yet unsolved. We used six adult beagles, in which a screw‐in lead was anchored in the His‐bundle region for observation of the pacing conditions and histopathologic changes of the conduction system over the course of 2 months. In the results, a satisfactory fixation was obtained using a conventional screw‐in lead and no histological influence on the conduction system was observed. The pacing threshold at the time of implantation was 1.15 ± 0.69V (3.23 ± 3.08 mA) in the pulse width of 0.5 ms. R wave amplitude, the impedance and slew rate were 7.28 ± 2.04 mV, 409 ± 102 Ohm, and 0.65 ± 0.41 V/s, respectively. Two months later, these parameters changed to 2.83 ± 1.06 V (10.4 ± 5.71 mA), 5.63 ± 1.62 mV, 310 ± 71.3 Ohm, and 0.49 ± 0.22 V/s, respectively. These results suggest the feasibility of clinical application of permanent His‐bundle pacing.
Pacing Threshold Trends and Variability in Modern Tined Leads Assessed Using High Resolution Automatic Measurements: Conversion of Pulse Width into Voltage Thresholds
Authors: DANILOVIC DEJAN , OHM OLE‐JØRGEN
Published: July 2006

With the aid of an algorithm for automatic pacing threshold (T) measurement in the atrium and ventricle, downloadable into implanted Thera pacemakers (Medtronic Inc.), we studied T evolution during lead maturation, T variation during activities of daily living, and various types of beat‐to‐beat T variations in three tined bipolar leads: 5.6‐mm2 steroid‐eluting (Medtronic Inc. models 4524 atrial‐J [n = 8] and 4024 ventricular [n = 8]), 1.2‐mm2 steroid‐eluting (Medtronic Inc. models 5534 atrial‐J [n = 9] and 5034 ventricular [n = 9]), and 8‐mm2 without steroid (Intermedics models 432–04 atrial‐J [n = 7] and 430–10 ventricular [n = 7]). The leads were implanted in 24 consecutive patients with intact AV conduction (required by the algorithm) and followed for up to 13–25 months after implantation. Since the algorithm determined pulse width Ts at different amplitudes that, depending upon T level, could range from 0.5 to 5.0 V, we invented a methodology for conversion of pulse width Ts into voltage Ts at 0.5 ms, to pool and present T data on a universal scale. Frequent, high resolution T measurements revealed details on the lead maturation process that we divided into three stages: initial T subsiding, first wave of T peaking, and a new, quicker or slower, T rise. Although there were notable differences in duration and magnitude of T peaking on the individual basis, differences between the three lead types and between the atrium and ventricle were demonstrable. The 1.2‐mm2 leads exhibited less T peaking than their predecessors 5.6‐mm2 leads and excellent positional stability, whereas 8‐mm2 leads demonstrated the most intensive T peaking and highest mean chronic T values. T changes during activities of daily living showed some tendencies—higher T during night and lower T during exercise —yet with a number of exceptions. The overall magnitude of daily T fluctuations was < 0.2 V in all but one lead, and 50% daily voltage safety margin would be sufficient. A 100% voltage safety margin may be inadequate for a 1‐year period during the chronic phase (after 6 months of implantation). A scheme for calculation of pulse width safety margins equivalent to voltage safety margins is given. Some leads can exhibit very large beat‐to‐beat T variations before, during, and after T peaking, and prospective algorithms for automatic T measurement should verify T values through more than 1–2 captured beats to obviate a great underestimation of the T providing consistent capture. T dependence upon pacing rate was negligible. Consistent‐capture hysteresis may, in conjunction with lead instability, be as much as 0.25 V. Therefore, it is better to use an incremental approach from below to T level during automatic T measurements.
Electromagnetic Interference of External Pacemakers by Walkie‐Talkies and Digital Cellular Phones: Experimental Study
Authors: TRIGANO ALEXANDRE J. , AZOULAY ALAIN , ROCHDI MOHAMED , CAMPILLO ALEXIS
Published: July 2006

A number of experimental and clinical studies have documented the risk potential of interference with implanted pacemakers by various types of cellular phones. Radiofrequency susceptibility of external medical equipment has also been reported in experimental studies. The purpose of this experimental study was to evaluate electromagnetic interference of external pacemakers by walkie‐talkies and digital cellular telephones. External bipolar pacing was monitored using a digital oscilloscope to record pacemaker pulses and electromagnetic interference separately. Tests with the walkie‐talkie, Private Mobile Radio (PMR) (160 MHz, 2.5 W) were conducted during the calling phase. Tests with the cellular phones, global system for mobile communications (GSM) (900 MHz, 2 W) and Digital Cellular System (DCS) (1,800 MHz, 1 W) were conducted in the test mode. Nine widely used external pacemakers from four manufacturers were tested. Various disturbances including pacing inhibition and asynchronous pacing were observed in eight pacemakers by the PMR, in four by the GSM phone, and in two by the DCS phone. The maximum distance that interference persisted ranged from 10–200 cm. This experimental study shows a potential risk of interference of external pacemakers by walkie‐talkies and cellular digital phones. Appropriate warnings should be issued against the potentially serious risks of using communication devices in the vicinity of acutely ill patients treated with temporary transvenous cardiac pacemakers.
Atrial and Ventricular Pressures in Atrial Flutter
Authors: ALBONI PAOLO , SCARFÒ SALVATORE , FUCÀ GIUSEPPE , PAPARELLA NELLY , MELE DONATO
Published: July 2006

The hemodynamic effects of atrial flutter (AF) are unknown. The purpose of the present study was to investigate the changes in atrial and ventricular pressures after induction of AF. In 23 patients with paroxysmal AF (age 59 ± 9 years), a hemodynamic study was performed both during sinus rhythm and after induction of the tachyarrhythmia. During AF, 13 patients showed a fixed 2:1 AV conduction and 10 patients showed variable conduction. Mean right and left atrial pressures increased (P < 0.001) and right and left ventricular end‐diastolic pressures decreased (P < 0.001) after induction of AF. Roth the increase in mean atrial pressures and the decrease in ventricular end‐diastolic pressures were present either in the patients with fixed 2:1 AV (heart rate: 133 ± 15 beats/min) or in those with variable conduction (heart rate 96 ± 15 beats/min), but were more marked in the former. AF produces an impairment of atrial function, as evidenced by the increase in mean atrial pressures and reduction in ventricular end‐diastolic pressures in the absence of an elevated heart rate. The mechanisms responsible for the increase in mean atrial pressures are unknown; however, atrial contractions against closed AV valves seem to play an important role.
Inducibility of Sustained Ventricular Tachycardia in a Closed‐Chest Ovine Model of Myocardial Infarction
Authors: REEK SVEN , BICKNELL JEANETTE L. , WALCOTT GREGORY P. , BISHOP SANFORD P. , SMITH WILLIAM M. , KAY G. NEAL , IDEKER RAYMOND E.
Published: July 2006

The two goals of this study were (1) to develop a closed‐chest animal model of monomorphic ventricular tachycardia; and (2) to investigate the effect of dual site pacing on inducibility of ventricular tachycardia. In the first part of the study, 10 of 14 sheep underwent successful induction of myocardial infarction by temporary balloon occlusion of the left anterior descending coronary artery. After a follow‐up period of 21–43 days, sustained monomorphic ventricular tachycardia could be induced during programmed electrical stimulation using a “clinical” stimulation protocol in 8 of the 10 sheep. The number of ventricular tachycardia episodes per animal varied between 5 and 70. Ventricular fibrillation was never induced during programmed electrical stimulation. Ventricular tachycardia episodes lasted from 30 seconds up to 15 minutes and were terminated by antitachycardia pacing or DC cardioversion. In the second part of the study, the effect of dual site stimulation on ventricular tachycardia inducibility was investigated. High current stimuli from an area within the infarcted zone were given with the S1 programmed stimulation protocol. This dual site stimulation showed no effect on ventricular tachycardia induction during programmed electrical stimulation. This animal model shows a high induction rate of sustained monomorphic ventricular tachycardia in the chronic phase of myocardial infarction. The high incidence of ventricular tachycardia inducibility provides a reliable tool to study new techniques for the prevention of ventricular tachyarrhythmias.