bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Transdermal Scopolamine on Heart Rate Variability in Patients with Severe Coronary Heart Disease
Authors: KOCHIADAKIS GEORGE E. , ROMBOLA AMALIA T. , KANOUPAKIS EMMANUEL M. , ZURIDAKIS EMMANUEL G. , SKALIDIS EMMANUEL I. , VARDAS PANOS E.
Published: July 2006

A decrease in cardiac parasympathetic tone is a recognized finding in patients with ischemia heart disease, correlating closely with disease severity and overall survival. The aim of this study was to assess whether transdermal Scopolamine (Tds), which increases parasympathetic tone in healthy volunteers, increases vagal tone in patients with severe CAD and whether it might have an antiischemic effect. Fifteen patients (10 men, aged 55 ± 8 years) with three‐vessel CAD, but with no prior MI and preserved ventricular function, underwent 24‐hour Holter monitoring and exercise testing before and after wearing a Scopolamine patch for 24 hours. Time‐domain measures of heart rate variability (HRV) and the total number and duration of ischemic episodes were obtained from the Holter recordings for each patient. Tds significantly (P < 0.05) increased the values of all HRV measures. Tds also reduced the total number of ischemic episodes (from 273 to 159, P < 0.05) and their total duration (from 136 to 46 min per patient, P < 0.05). Tds also increased treadmill exercise duration from 293 ± 101 to 345 ± 95 seconds (P <0.05) and the time to 1‐mm ST depression from 177 ± 105 to 244 ± 128 seconds (P < 0.02), while maximum ST depression was reduced from 2.86 ± 0.6 to 2.3 ± 0.3 (P < 0.05). No significant side effects were observed. Tds modifies the autonomic balance in patients with severe CAD toward a condition associated with a better prognosis. It may also be useful as an adjunctive treatment for ischemic heart disease.
Influence of Cardiac Dysfunction on Fast Sodium Current Regulation by Forskolin
Authors: KIRSTEIN MICHAEL , KATZER ASTRID , HU KAI , GAUDRON PETER , ERTL GEORG , LANGENFELD HEINER , KOCHSIEK KURT
Published: July 2006

There are several reports of an altered β‐adrenergic pathway in heart failure. Since the fast cardiac sodium current (INA+) is also subject to β‐receptor dependent regulation, we investigated its regulation in a model of cardiac dysfunction. Adenylyl cyclase was stimulated directly with forskolin as one step in the β‐adrenergic pathway. Twelve‐week‐old Wistar rats were infarcted by ligation of the left anterior descending coronary artery. Eight weeks later, the induced hemodynamic changes were evaluated. The left ventricular end‐diastolic pressure (LVEDP) was used as a measure of the hemodynamic effects of the myocardial infarction. With the loose patch clamp technique, INa+ was measured in intact papillary muscles at an external sodium concentration of 150 mmol/L. Potential dependent availability was tested with pulses to 0 mV from various conditioning potentials. In animals with minor infarction (n = 7, LVEDP = 7.7 ± 0.9 mmRgj, forskolin (3 mmol/L) increased the maximal available INa+ to 109%± 13% of baseline values. This increase was nearly the same in the group with significant infarctions (n = 7, LVEDP = 15.7 ± 1.6 mmHg) to 113%± 6%. Thus, although we previously observed a reduction of the isoproterenol induced increase of INA + in rats with significant myocardial infarctions, this increase remalns the same when adenylyl cyclase is stimulated directly. This is consistent with a direct β‐receptor down‐regulation or desensitization.
An Implantable Intracardiac Accelerometer for Monitoring Myocardial Contractility
Authors: RICKARDS ANTHONY F. , BOMBARDINI TONING , CORBUCCI GIORGIO , PLICCHI GIANNI ,   on behalf of THE MULTICENTER PEA STUDY GROUP
Published: July 2006

As the myocardium contracts isometrically, it generates vibrations that are transmitted throughout the heart. These vibrations can be measured with an implantable microaccelerometer located inside the tip of an otherwise conventional unipolar pacing lead. These vibrations are, in their audible component, responsible for the first heart sound. The aim of this study was to evaluate, in man, the clinical feasibility and reliability of intracavity sampling of Peak Endocardial Acceleration (PEA) of the first heart sound vibrations using an implantable tip mounted accelerometer. We used a unidirectional accelerometer located inside the stimulating tip of a standard unipolar pacing lead: the sensor has a frequency response of DC to 1 kHz and a sensitivity of 5 mV/G (G ‐ 9.81 m/s−2). The lead was connected to an external signal amplifier with a frequency range of 0.05–1,000 Hz and to a peak‐to‐peak detector synchronized with the endocardial R wave scanning the isovolumetric contraction phase. Following standard electro‐physiological studies, sensor equipped leads were temporarily inserted in the RV of 15 patients (68 ± 15 years), with normal regional and global ventricular function, to record PEA at rest, during AAI pacing, during VVI pacing, and during dobutamine infusion (up to 20 |mg/kg per min). PEA at baseline was 1.1 G ± 0.5 (heart rate = 75 ± 14 beats/rain) and increased to 1.3 G ± 0.9 (P = NS vs baseline) during AAI pacing (heart rate = 140 beats/min) and to 1.4 G ± 0.5 (P = NS vs baseline) during VVI pacing (heart rate = 140 beats/min). Dobutamine infusion increased PEA to 3.7 G ± 1.1 (P < 0.001 vs baseline), with a heart rate of 121 ± 13 beats/min. In a subset of three patients, simultaneous hemodynamic RV monitoring was performed to obtain RV dP/dtmax, whose changes during dobutamine and pacing were linearly related to changes in PEA (r = 0.9; P < 0.001). In conclusion, the PEA recording can be consistently and safely obtained with an implantable device. Pharmacological inotropic stimulation, but not pacing induced chronotropic stimulation, increases PEA amplitude, in keeping with experimental studies, suggesting that PEA is an index ofmyocardial contractility. Acute variations in PEA are closely paralleled by changes in R V dP/dtmax, but are mainly determined by LV events. The clinical applicability of the method using RV endocardial leads and an implantable device offers potential for diagnostic applications in the long‐term monitoring of myocardial function in man.
Heart Rate Variability After Cardiac Transplantation in Humans
Authors: RAMAEKERS DIRK , ECTOR HUGO , VANHAECKE JOHAN , van CLEEMPUT JOHAN , van de WERF FRANS
Published: July 2006

The reappearance of cardiac innervation after cardiac transplantation remains a matter of debate. We evaluated the ability of heart rate variability (HRV) analysis to detect the extent and time course of functional cardiac allograft reinnervation. Time‐ and frequency‐domain analysis of heart rate was performed on Holter recordings of 120 heart transplant and four heart‐lung transplant recipients. A high frequency (HF) component was clearly distinguished on visual inspection of power spectral density in 42 patients. In eight patients an HF component of normal magnitude was detected. The other 34 patients in this group, including all four heart‐lung transplants, presented with a very small HF component. The other 82 patients showed a flat spectrum. The group with an HF component of normal amplitude was significantly different, compared to the other groups, for all HRV parameters. Serial plotting of HRV parameters of the patients with an HF component of normal amplitude against time posttransplant, revealed, from 12 months onwards, a progressive increase of parameters denoting HF variability. In five heart transplant patients with acute allograft rejection, the use of HRV analysis for rejection monitoring was unsuccessful. These results suggest that, inasmuch as the HF component of HRV is caused by parasympathetic cardiac innervation, the HF component of normal amplitude, observed in only a minority of cardiac transplant recipients (6%), is a marker for parasympathetic reinnervation. The evolution over time of this HF component is compatible with a biological phenomenon as gradual parasympathetic reinnervation of the sinus node.
Idiopathic Right Ventricular Outflow Tract Tachycardia: A Clinical Approach
Authors: LERMAN BRUCE B. , STEIN KENNETH M. , MARKOWITZ STEVEN M.
Published: July 2006

Right ventricular outflow tract (RVOT) tachycardia is the most common form of idiopathic ventricular tachycardia (VT). Phenotypically, RVOT tachycardia segregates into two predominant forms, one characterized by repetitive monomorphic nonsustainnd VT and the other by paroxysmal exercise induced sustained VT. There is an increasing body of evidence to support the concept that both forms of tachycardia reflect disparate clinical manifestations of an identical cellular mechanism (i.e., cAMP‐mediated triggered activity), which is identified clinically by the tachycardia's sensitivity to adenosine. The clinical characteristics, natural history, and approaches to therapy of RVOT tachycardia are delineated herein.
Effect of Dual Chamber Atrioventricular Sequential Pacing on Coronary Flow Velocity in a Patient with Hypertrophic Obstructive Cardiomyopathy
Authors: TAKEUCHI MASAAKI , ABE HARUHIKO , KUROIWA AKIO
Published: July 2006

Effects of dual chamber A V sequential pacing on coronary flow velocity, especially systolic reversal flow, were tested in a patient with hypertrophic obstructive Cardiomyopathy. AV sequential pacing with shorter AV delays reduced the systolic reversal flow in the coronary artery, and improved the pressure gradient of the left ventricular outflow tract.
Effects of Exercise on Signal‐Averaged Electrocardiogram
Authors: BEAUREGARD LOU‐ANNE M. , VOLOSIN KENT J. , ASKENASE ALAN D. , WAXMAN HARVEY L.
Published: July 2006

Signal averaging can be used to assess changes in myocardial activation under a variety of physiological conditions including stress. This study prospectively evaluated patients who underwent rest and exercise recording of signal‐averaged electrocardiograms. The 163 patients were divided into three groups based on thallium results: normal (group I), reperfusion (group II), and fixed defect (group III). Patients in group I showed shortening of the high frequency duration (P = 0.02) and the duration of the low amplitude signal (P = 0.024) after exercise. In these patients the terminal root mean square amplitude (RMSA) also increased significantly (P = 0.005). However, patients who were in either group II or group III showed little change in signal averaging measurements after exercise. The amplitude of the QRS in V5 and the RMSA of the total QRS also increased in all groups following exercise, with a lesser increase in the patients with reperfusion by thallium imaging (group II). There was no change among groups in the incidence of ventricular late potentials with exercise. This suggests that patients with ischemia or infarction may not have the same response to an increase in sympathetic tone with exercise as patients without abnormalities of cardiac perfusion. The clinical implications of these findings may include demonstration that an area of slow conduction exists in these latter two groups of patients.
Time‐Domain Signal‐Averaged Electrocardiogram in Nonischemic Ventricular Tachycardia
Authors: FAUCHIER JEAN‐PAUL , FAUCHIER LAURENT , BABUTY DOMINIQUE , COSNAY PIERRE
Published: July 2006

The prevalence of late ventricular potentials (LVPs) detected by signal averaged ECG (SAECG) is variable in nonischemic heart diseases. In idiopathic dilated cardiomyopathy, the prevalence increases from about 25% to 70%‐90% in cases of spontaneous sustained ventricular tachycardia (VT), is not significantly correlated with hemodynamic and Holter data, and has a good positive predictive value for induced and spontaneous sustained VT. However, its predictive value for cardiac death has not been established. In primary hypertrophic cardiomyopathy, LVPs are rare (about 10%), not correlated to hemodynamic data, enhanced in cases of spontaneous sustained VT (up to 77%), and have a good predictive value of induced VT. LVP‐SAECG are frequent in arrhythmogenic right ventricular dysplasia (ARVD) (70%‐80%). They can identify patients with VT and an unapparent or limited form of this disease, or ARVD with few ventricular arrhythmias. The prevalence (26%‐37%) of LVPs in mitral valve prolapse is clearly higher than in normal individuals or in other valvular diseases and is enhanced in cases of spontaneous and induced VT. Its significance remains speculative. After surgical repair of tetralogy of Fallot, LVPs can identify a group of patients with higher probability of induced and spontaneous risk of VT. The usefulness and significance of LVPs in other nonischemic cardiac diseases have not to date been established. In “true” idiopathic VT, without proved structural cardiac disease, the prevalence of LVPs does not exceed that observed in normal individuals (0%‐5%), but in “apparent” idiopathic VT the prevalence of LVPs rises to 20%‐40%. In these latter cases more invasive techniques must be used to discover a limited form of myocardiopathy.
Reliability and Variability of Impedance Measured by Real‐Time Telemetry
Authors: SCHUCHERT ANDREAS , CAPPATO RICCARDO , KUCK KARL‐HEINZ , MEINERTZ THOMAS
Published: July 2006

With the aim to detect dysfunction of pacing leads, most present‐day pacemakers measure pacing impedance by means of real‐time telemetry. The recommended setting for impedance measurement is 5.0 V for pulse amplitude and 0.5 ms for pulse duration. Availability of reliable settings would facilitate impedance measurements during follow‐up. The purpose of the present study was twofold: (1) to assess whether telemetrically measured impedance of the studied pacemaker is similar to impedance measured at implantation; and (2) to evaluate whether the pacemaker setting influences telemetrically measured impedance. Sixty‐five consecutive patients receiving VVI(R) pacemakers were studied; in all patients, impedance measured at implantation by a pacing system analyzer was compared to measurements obtained telemetrically within 1 day after implantation. In 44 other patients, impedance was determined 3 months after implantation at 60 and 120 ppm (n = 44), twice at 60 ppm (n = 42), and 12 months after implantation at 60 ppm (n = 34). For each measurement, pulse amplitude was programmed to 0.8, 1.6, 2.5, 5.0, and 8.0 V, and pulse duration to 0.05, 0.25, 0.50, and 1.00 ms. Impedance at implantation (606 ± 113 ohms) did not differ from the data obtained with telemetry (629 ± 113 ohms; P = NS). Different pacing rates, repeat measurements, and follow‐up time failed to show any influence on impedance. Measurement tolerance was < 10% for 15 of 19 studied settings other than 5.0 V and 0.5 ms. Conclusion: The studied pacemakers provide reliable data for telemetrically measured impedance. Telemetrical impedance does not necessarily have to be measured at 5.0 Vand 0.5 ms. These findings should be considered for measurement and interpretation of real‐time telemetry impedance during follow‐up.
Pacemaker Upgrade for Recurrent Pacemaker Syndrome Using a Redundant Contralateral Electrode in a Patient with Bilateral Venous Stenoses
Authors: SULKE NEIL , TAN KIM , BOSTOCK JULIAN
Published: July 2006

Following His‐bundle ablation and VVIR pacemaker implantation, severe pacemaker syndrome developed and was treated with DDDR pacing, in a 70‐year‐old woman. Due to bilateral subclavian vein stenoses, DDDR pacing could not be maintained and an unusual method of restoring atrioventricular synchrony is described using the contraiateral redundant atrial electrode connected to the ipsilateral dual chamber pacemaker and ventricular electrode.
Effects of High Energy Shocks on Pacing Impedance During Transvenous ICD Implantation
Authors: HIDDEN‐LUCET FRANCOISE , HARTUNG WOLFGANG M , McTEAGUE KEVIN K. , WALTER PAUL F. , LANGBERG JONATHAN J.
Published: July 2006

The purpose of the current study was to characterize the effects of transvenous ICD shocks on myocardial impedance. Rather than recording impedance during shocks, it was measured during continuous pacing in order to minimize confounding effects such as electrode polarization. Pacing impedance (reflecting the combined impedances of the electrode‐tissue interface, myocardium, and blood pool) was measured every 5 seconds before and after 58 single shocks in 22 patients undergoing ICD implantation with a Transvene (n = 14) or Endotak (n = 8) lead. There was a progressive and long‐lasting decrease in impedance after shocks. The magnitude of this change was similar for 0.6‐J test shocks and shocks ≥ 5 J (28 ± 32 Ω vs 23 ± 16 Ω P = 0.8). However, the drop in impedance was more abrupt after high energy shocks. Because impedance continued to decline throughout the 5‐minute interval between shocks, successive shocks had a cumulative effect, with a decrease of 46 ± 42 Ω after four discharges. In conclusion, a progressive decline in pacing impedance is a characteristic response to transvenous ICD discharges.
Performance of Implantable Defibrillator Pacing/Sensing Lead Adapters
Authors: SGARBOSSA ELENA B. , SHEWCHIK JEANNE , PINSKI SERGIO L.
Published: July 2006

The wide variety of implantable defibrillators (ICDs) available from different manufacturers and the lack of universal industry standards has resulted in the frequent need for lead adapters at time of ICD implant or change. We analyzed the performance of 81 consecutive ICD sensing/pacing lead adapters used between 1988 and 1993. A total of 66 adapters was used for new epicardial systems, and 15 adapters served as lead connectors during ICD generator replacement, Pacing/sensing lead adapters used were: model LA‐201 (n = 28; 34.5%); model 030–308 (n = 26; 32%); model 5866–24 (n = 15; 18.5%); and miscellaneous (n = 12; 15%). After a mean follow‐up of 21 ± 16 months, nine pacing/sensing lead adapters had documented or strongly suspected failure. Most often pacing/sensing lead adapters presented clinically as frequent aborted shocks. Actuarial probability of freedom from failure for model LA‐201 was 83% at 1 year, and 72% at 2 and 3 years; this was poorer than for the other sensing leads combined (P = 0.01; hazard ratio = 4.92; 95% confidence intervals = 1.2–20; log‐rank test). In conclusion, pacing/sensing lead adapters are a potential source of ICD system complications. Performance is dissimilar among different models; specifically, model LA‐201 may not be safe in the long‐term, and patients with this lead adapter need to be closely monitored.
The Use of Methylphenidate in the Treatment of Refractory Neurocardiogenic Syncope
Authors: GRUBB BLAIR P. , KOSINSKI DANIEL , MOUHAFFEL ASSAD , POTHOULAKIS ANTHONY
Published: July 2006

Recurrent neurocardiogenically mediated episodes of hypotension and bradycardia are a common cause of recurrent syncope that can be identified by head upright tilt table testing. While the use of β‐blockers, theophylline, fludrocortisone, disopyramide, and serotonin re‐uptake inhibitors can be helpful in preventing further episodes, some patients are unresponsive to or poorly tolerant of these agents. We investigated the use of the central nervous system stimulant and peripheral vasoconstrictor methylphenidate in preventing both tilt induced and spontaneous neurocardiogenic syncope. Seven patients (all women, mean age 31 ± 15 years) with recurrent syncope and positive head upright tilt induced hypotension/bradycardia (refractory to normal therapy) were placed on methylphenidate 10 mg orally three times per day. Six of the seven patients became both tilt negative and clinically asymptomatic over a 7‐month follow‐up period. We conclude that methylphenidate may be an effective therapy in patients with recurrent neurocardiogenic syncope refractory to other forms of therapy.
Electrograms for Identification of the Atrial Ablation Site During Catheter Ablation of Accessory Pathways
Authors: MONTENERO ANNIBALE SANDRO , CREA FILIPPO , BENDINI MARIA GRAZIA , PELARGONIO GEMMA , INTINI ANSELMA , FINOCCHIARO MARIA LUISA , BISCIONE FRANCESCO , PIGOZZI FABIO , BELLOCCI FULVIO , ZECCHI PAOLO
Published: July 2006

Background: Catheter ablation of accessory pathways using radiofrequency current has been shown to be effective in patients with Wolff‐Parkinson‐White syndrome, by using either the ventricular or atrial approach. However, the unipolar electrogram criteria for identifying a successful ablation at the atrial site are not well established. Methods and Results: One hundred patients with Wolff‐Parkinson‐White were treated by delivering radiofrequency energy at the atrial site. Attempts were considered successful when ablation (disappearance of the delta wave) occurred in < 10 seconds. In eight patients with concealed pathway, the accessory pathway location was obtained by measuring the shortest V‐A interval either during ventricular pacing or spontaneous or induced reciprocating tachycardia. In 92 patients both atrioventricular valve annuli were mapped during sinus rhythm, in order to identify the accessory pathway (K) potential before starting the ablation procedure. When a stable filtered (30–250 Hz) “unipolar” electrogram was recorded, the following time intervals were measured: (1) from the onset of the atrial to the onset of the K potential (A‐K); (2) from the onset of the delta wave to the onset of the K potential (delta‐K); and (3) from the onset of the K potential to the onset of the ventricular deflection (K‐ V). During unsuccessful versus successful attempts, A‐K (51 ± 11 ms vs 28 ± 8 ms, P < 0.0001 for left pathways [LPs]; and 44 ± 8 ms vs 31 ± 8 ms, P < 0.02 for right pathways [RPs]) and delta‐K intervals (2 ± 9 ms vs ‐18 ± 10 ms, P < 0.0001 for LPs; and 13 ± 7 ms vs 5 ± 8 ms, P < 0.02 ms for RPs) were significantly longer. Conclusions: Short A‐K interval (< 40 ms), and a negative delta‐K interval recorded from the catheter positioned in the atrium are strong predictors of successful ablation of LPs and RPs. Therefore, the identification of the K potential appears to be of paramount importance for positioning of the ablation catheter, followed by analysis of A‐K and delta‐K unipolar electrogram intervals. However, it appears that the mere recording of K potential is not, per se, predictive of successful outcome, but rather the A‐K and delta‐K interval.
Atrial Flutter Mapping and Ablation II. Radiofrequency Ablation of Atrial Flutter Circuits
Authors: Barol S. Serge , COSIO FRANCISCO G. , ARRIBAS FERNANDO , LÓPEZ‐GIL MARÍA , GONZÁLEZ H. DANIEL
Published: July 2006

The definition of the anatomical substrate of reentry in at rial flutter has allowed the recognition of narrow, critical areas of the circuit, where radiofrequencv ablation can interrupt reentry. In common flutter the isthmus between the inferior vena cava and the tricuspid valve appears the best target, but ablation between the coronary sinus and tricuspid valve can also be effective in some cases. In atypical flutter using the same circuit as common flutter in a “clockwise” direction, ablation of the same isthmus is effective. Flutter interruption is the main objective, but it does not mean complete isthmus ablation. If flutter remains inducible, new applications are delivered in the isthmus, until it is made noninducible. Complications are rare. Despite attaining noninducibility, flutter may recur, and new procedures may he needed to prevent recurrence. Atrial fibrillation can occur in up to 30% of the cases during follow‐up, but it is generally well controlled with antiarrhythmic drugs, that were ineffective to treat flutter before ablation. In reentry circuits based on surgical atrial scars, ablation of an isthmus between the scar and the inferior vena cava can also be effective. Left atrial circuits are not known well enough to guide successful ablation.
Radiofrequency Catheter Ablation of Left Atrial Tachycardia Originating Within the Pulmonary Vein in a Patient with Dextrocardia
Authors: HATALA ROBERT , WEISS CHRISTIAN , KOSCHYK DIETMAR H. , SIEBELS JURGEN , CAPPATO RICCARDO , KUCK KARL‐HEINZ
Published: July 2006

A case is presented of a 38‐year‐old male with dextrocardia in whom radiofrequency current ablation of an incessant atrial tachycardia originating within the infero‐lateral pulmonary vein was achieved. Activation mapping with detection of the earliest atrial activation was used for identification of the arrhythmogenic focus. In addition to fluoroscopy, trans‐ esophageal echocardiography was used for catheter guidance during the transseptal puncture. The present experience suggests that location of an arrhythmogenic focus within the pulmonary venous system should be considered whenever early atrial activation during ectopic atrial tachycardia is recorded at the junction between thfi left atrium and the pulmonary veins.
The Steroid‐Eluting Electrode: A 10‐Year Experience
Authors: MOND HARRY G. , STOKES KENNETH B.
Published: July 2006

The benefits of steroid‐eluting electrodes in reducing stimulation thresholds are well established. A question frequently asked, however, is how long does such an electrode maintain its effect on reducing stimulation threshold? Two studies were designed to answer this question by reporting a long‐term prospective human implant review as well as an analytical examination of explanted leads from both humans and animals to determine the amount of remaining steroid in the silicone plug. A previously reported double‐blind human study using 20 implanted unipolar ventricular leads, 10 with and 10 without steroid, was followed for 10 years. Pulse width stimulation thresholds were determined at regular intervals using a customized VVIC pulse generator programmed to 1.5‐V output. Throughout the study period, the mean stimulation thresholds for the steroid‐eluting leads remained almost constant, with a narrow standard deviation, whereas the leads without steroid showed an unpredictable rise and a wide standard deviation. AH patients with the steroid‐eluting electrodes were paced at 1.5 V. and the four surviving patients still have their original pulse generators. In the second study, the remaining steroid from 25 explanted leads (18 canine and 7 human), were analyzed and graphed against implant times that ranged from 1–350 weeks. Extrapolation of the line of best fit suggests that about 20% of the steroid is still present at 10 years and 18% at 20 years. Only small quantities of steroid are required for its stimulation threshold lowering effect, which continues clinically to at least 10 years. Sufficient quantity of steroid may well be present at 20 years.
Short Biphasic Pulses from 90 Microfarad Capacitors Lower Defibrillation Threshold
Authors: SWERDLOW CHARLES D. , KASS ROBERT M. , DAVIE SCOTT , CHEN PENG‐SHENG , HWANG CHUN
Published: July 2006

For defibrillation between right ventricular and retropectoral patch electrodes using truncated exponential pulses, the stored energy defibrillation threshold (DFT) is lower for short pulses from small 60‐μF capacitors than for conventional pulses from 120‐μF capacitors, but 60‐μF pulses frequently require higher voltages than are currently used. The goal of this study was to determine if DFT could be reduced by intermediate size 90‐μF capacitors. This study compared biphasic waveform DFTs for 120μF‐65% tilt pulses, 90μF‐65% tilt pulses, and 90 μF‐50% tilt pulses in 20 patients at defibrillator implantation. The 90μF‐50% tilt pulses were selected because their duration is half that of 120μF‐65% tilt pulses. The stored energy DFT for 90 μF‐50% tilt pulses (9.1 ± 4.3 J) was less than both the DFT for 120 μF‐65% tilt pulses (12.0 ± 5.5 J, P < 0.005) and the DFT for 90μF‐65% tilt pulses (11.6 ± 5.8 J, P < 0.005). There was no significant difference between the latter two values. The voltage DFTs for 90 μF‐50% pulses (436 ± 113 V) and 120 μF‐65% tilt pulses (436 ± 104 V) were not statistically different; the voltage DFT for 90 μF‐65% tilt pulses was higher than for either of the other two pulses (490 ± 131, P < 0.005). The DFT was 20 } or greater in three patients for both 120 μF‐65% tilt pulses and 90 μF‐65% tilt pulses, but it was 16 J or less in all patients for 90 μF‐50% tilt pulses. When pathways were dichotomized by the median resistance of 71 Ω, 90 μF‐50% tilt pulses significantly reduced DFTs compared to 120 μF‐65% tilt pulses for higher resistance pathways (9.2 ± 4.0 J vs 13.0 ± 6.2 J, P = 0.002), but not lower resistance pathways (9.0 ± 4.8 J vs 10.9 ± 4.6 J, P = NS). For the electrode configuration tested, biphasic 90 μF‐50% tilt pulses reduce stored energy DFT in comparison with 120 μF‐65% tilt pulses without increasing voltage DFT. However, 90 μF‐65% tilt pulses provide no benefit.
Permanent Pacemaker Lead Implantation via the Transhepatic Route
Authors: FISHBERGER STEVEN B. , CAMUNAS JORGE , RODRIGUEZ‐FERNANDEZ HECTOR , SOMMER ROBERT J.
Published: July 2006

A 4‐year‐old male with transposition of the great arteries, status post‐Senning repair, required placement of an atrial pacemaker for sinus node dysfunction and atrial flutter. Multiple systemic venous occlusions precluded conventional transvenous lead implantation. A transhepatic approach resulted in successful placement of an endocardial atrial pacing lead.
“Peudo” Late Potentials Unmasked by Spectrocardiography
Authors: GOLDMAN DANIEL S. , HENKIN RAPHAEL , KELEN GEORGE
Published: July 2006

We present a patient with chronic obstructive pulmonary disease and sustained ventricular tachycardia in the setting of unstable coronary artery disease. Signal‐averaged ECG (SAECG), inadvertently performed during an atrial tachycardia with 2:1 atrioventricular (AV) block, was abnormal by time‐domain analysis, but was normal by a relatively new frequency analysis technique of the entire QRS (spectocardiography). The patient was noninducible for sustained ventricular arrhythmias. Following cardioversion to sinus rhythm. SAECG was normal by time‐domain analysis and Spectrocardiography. This technique may show promise in the management of patients who are at risk for sustained ventricular arrhythmias, particularly those who cannot be evaluated by time‐domain analysis.
Pacemaker Follow‐Up with Prolonged Intervals in the Stable Period 1 to 5 Years Postimplant
Authors: GRENDAHL HELGE
Published: July 2006

This pilot study focuses on pacemaker follow‐up in the technically stable period 1–5 years after a pacemaker implantation. Two hundred and thirty selected patients with single chamber pacemakers (215 WI, 15 AAI) had their follow‐up intervals prolonged to 2–4 years in this period. Sixty‐six patients fulfilled the study period uneventfully and 21 are still pending. Sixty‐nine patients had unscheduled visits to the pacemaker clinic. Of these, 7 were reoperated (1 for exit block, 4 had pocket erosions, and 2 were upgraded to DDD). Nine were reprogrammed (1 for sensing failure, 1 had the pulse duration increased, and in 7 the pacing rate was changed). Seventy‐four patients died. In 63, the cause of death is known not to be pacemaker related. Six died suddenly, and in five cases, the cause of death is unknown. This study indicates that frequent follow‐up visits may be omitted in this period in selected patients with single chamber pacemakers. A prerequisite is that the patients are registered at a pacemaker clinic and have easy access to the physician whenever they suspect pacemaker related problems.
Assessment of Time Domain and Spectral Components of Heart Rate Variability Immediately Before Ischemic ST Segment Depression Episodes
Authors: DILAVERIS POLYCHRONIS E. , ZERVOPOULOS GEORGE A. , PSOMADAKI ZOI D. , MICHAELIDES ANDREAS P. , GIALOFOS JOHN E. , TOUTOUZAS PAVLOS K.
Published: July 2006

In an attempt to study autonomic function during the 5‐minute period preceding ischemic ST segment depression (↓ST) episodes, we selected 138 ↓ST episodes, without preceding ↓ST during the last 15 minutes before each episode, from the Holler tapes of 35 patients with multivessel coronary artery disease. For the 5‐minute period preceding each ↓ST episode, we calculated the following heart rate variability (HRV) indices; the mean RR interval (RR5), the standard deviation of all RR intervals (SD Index5), the corresponding coefficient of variation (CV5), and the natural log (Ln) of the spectral components, total power at 0.000 to 0.400 Hz (TP5), low frequency power at 0.040 to 0.150 Hz (LF5), high frequency power at 0.150 to 0.400 Hz (HF5), and the ratio of the low to high frequency power (LF5/HF5). As HRV indices of the 24‐hour period, we calculated the respective RR, SD Index, CV, LnTP, LnLF, LnHF, and Ln LF/HF. RR5, SD Index5, CV5, and LnTP5 were all significantly lower than RR (t =−5.343, p = 3.7 × 10−7), SD Index (t =−19.091, p = 1.99 × 10−40), CV(t ‐15.780, p = 1.28 × 10−32), and LnTP (t =−3.210, p = 0.0016), respectively. LnHF5 was inversely correlated with the magnitude of the ↓ST; r =−0.174, P < 0.05, and CV5 was inversely correlated with the natural log (Ln) of the ischemic event duration; r =−0.183, P < 0.05. Analogous results were obtained for both the painful and silent ↓ST episodes. It is concluded that HRV is decreased during the 5‐minute period preceding ↓ST episodes, and is inversely related with the magnitude and the duration of the ↓ST.
Reversibility of “Tachycardia Induced Cardiomyopathy” Following the Cure of Idiopathic Left Ventricular Tachycardia Using Radiofrequency Energy
Authors: SINGH BALBIR , KAUL UPENDRA , TALWAR KEWAL K. , WASIR HARBANS S.
Published: July 2006

We report a cose of incessant ventricular tachycardia with right bundle branch block and left axis deviation morphology resulting in severe LV dysfunction and congestive heart failure. Radiofrequency ablation of the appropriate site in the region of posteroapical part of the LV septum resulted in the cure of the arrhythmia. On a 3‐month follow‐up, the LV size and function returned to normal.
Impedance of Pacemaker Leads: Correlation of Different Methods
Authors: SIEGMUND JOACHIM B. , WILSON JOHN H. , LATTNER STEPHEN E. , GRANNEMAN KIMBERLY , JOHNSON ROBERT
Published: July 2006

This study compares three different pacing system analyzers, which measure impedance at different points during an impulse, with measurements telemetered from implanted pacemakers from four different manufacturers. Measurements were obtained at the time of implantation in a group of 103 patients. The measurements obtained by these different methods differ significantly from each other; the later during the impulse the impedance is measured, the higher in general its value. Interpretation of impedance values should take into account the technique of measurement.
Changes of QT Intervals Associated with Postural Change in Patients with Chronic Atrial Fibrillation
Authors: MALIK MAREK , JANOTA TOMAS , NAGAYOSHI HIROKAZU , HNATKOVA KATERINA , CAMM A. JOHN
Published: July 2006

Although different computerized systems have been developed to localize specific patterns in electrocardiographic (ECG) signals, it is still difficult to detect T waves and measure QT intervals during atrial fibrillation. This article demonstrates the use of an auto‐correlation (ECG) based system that was used to investigate the dynamicity of QT intervals related to active postural change in patients with chronic atrial fibrillation. Twenty patients (9 male, mean age 63 years) with chronic atrial fibrillation (8 idiopathic, 12 organic heart disease) were examined. Seventeen of these patients were on digoxin, but patients with other conditions potentially affecting the autonomic nervous system were not included. A 3‐channel ECG was recorded digitally during active postural change from supine to standing. Data were first analyzed by the Burdick Altair system and subsequently processed using an in‐house software package evaluating auto‐correlations of ECG signals. An ECG channel with suitable repolarization patterns was found in 15 patients. The mean QT interval of 409.8 ± 11.1 ms (mean ± SE) recorded during supine position shortened to 401.9 ± 9.89 ms during the first minute of active standing (P < 0.05) and to 394.8 ± 10.0 ms during the second minute of active standing (P < 0.005). It did not further change during the subsequent minutes of active standing. The study shows that automatic detection of QT intervals during atrial fibrillation is possible. Although the effect of position change of the heart cannot be completely excluded, the study suggests that QT interval is changed directly by autonomic nervous mechanisms rather than indirectly via the mean heart rate.
Ventricular Tachycardia Induced Cardiomyopathy: Improvement with Radiofrequency Ablation
Authors: JAGGARAO NATTAMA S.V. , NANDA ARDAMAN S. , DAUBERT JAMES P.
Published: July 2006

Cardiomyopathy and congestive heart failure due to ventricular and supraventricular tachycardia is a well‐recognized phenomenon. The mechanism of such Cardiomyopathy is not clear. Ablation of the supraventricular tachycardia focus, either surgically or electrically, has been reported to result in the resolution of the left ventricular dysfunction. Similarly, the treatment of ventricular tachycardia with surgery or antitachycardia pacing has also been reported to result in improved ventricular systolic function. We present here a case of improvement in left ventricular systolic function after successful radiofrequency ablation of the ventricular tachycardia focus in the right ventricular outflow tract. We postulate that Cardiomyopathy was due to the incessant or frequent ventricular tachycardia. To the best of our knowledge, this is the first such case being reported.
Ten‐Year Follow‐Up of a Patient with Pacemaker Induced Superior Vena Cava Syndrome
Authors: KATAOKA HAJIME
Published: July 2006

A woman with persistent pacemaker induced superior vena cava syndrome was stable for 10 years. Serial follow‐up venography, however, demonstrated a continuous process of major vein occlusion and the development of collateral circulation, the effectiveness of which warrants a favorable prognosis in this pacemaker related syndrome.
The Medical Therapy of Cardioinhibitory Syncope in Pediatric Patients
Authors: DEAL BARBARA J. , STRIEPER MARGARET , SCAGLIOTTI DANIEL , HULSE EDDIE , AULD DEBBIE , CAMPBELL ROBERT , STRASBURGER JANETTE F. , BENSON D. WOODROW
Published: July 2006

A small percentage of pediatric patients with neurally mediated syncope will have an asystolic response during upright tilt table testing. The purpose of this study is to evaluate the incidence of asystole during tilt table testing, and to assess the outcome of medical management of such patients. Of 398 patients undergoing evaluation for recurrent syncope between January 1989 and 1994, 18 (4.5%) experienced asystole lasting ≥ 5 seconds during baseline tilt test. Patients had experienced a mean of four episodes of syncope, with a mean age at the time of tilt test of 11.1 ± 4.0 years. The median duration of asystole was 10 seconds (range 5–40 s). Treatment was individualized to increased fluids and salt intake (3 patients), metoprolol (8 patients), pseudoephedrine (4 patients), disopyramide (1 patient), or combination therapy with fludrohydrocortisone (2 patients). During a median duration of follow‐up of 31 months, no additional syncope was experienced by 78% of patients. Recurrent syncope in 4 patients was associated with either noncompliance or discontinuation of therapy in 3 patients; in 1 patient, increasing the dose of metoprolol was effective in preventing recurrences. We conclude that young patients with recurrent syncope and asystole during tilt test may be safely and effectively managed with pharmacological therapy, without resorting to pacemaker implantation.
Evaluation of the Safety and Efficacy of Deep Sedation for Electrophysiology Procedures Administered in the Absence of an Anesthetist
Authors: GEIGER MARY JANE , WASE ABDUL , KEARNEY MARGARET M. , BRANDON M. JOAN , KENT VIRGINIA , NEWBY KEITH H. , NATALE ANDREA
Published: July 2006

Several procedures performed in the electrophysiology laboratory (EP lab) require surgical manipulation and are lengthy. Patients undergoing such procedures usually receive general anesthesia or deep sedation administered by an anesthesiologist. In 536 consecutive procedures performed in the EP lab, we assessed the safety and efficacy of deep sedation administered under the direction of an electrophysiologist and in the absence of an anesthetist. Patients were monitored with pulse oximetry, noninvasive blood pressure recordings, and continuous ECGs. The level of consciousness and vital signs were evaluated at 5‐minute intervals. Deep sedation was induced in 260 patients using midazolam, phenergan, and meperidine, then maintained with intermittent dosing of meperidine at the following mean doses: midazolam 0.031 ± 0.024 mg/kg; phenergan 0.314 ± 0.179 mg/kg; and meperidine 0.391 ± 0.167 mg/kg per hour. In the remaining 276 patients, deep sedation was induced with midazolam and fentanyl and maintained with a continuous infusion of fentanyl at a mean dose of 2.054 ± 1.43 μg/kg per hour. Fourteen patients experienced a transient reduction in oxygen saturation that was readily reversed following administration of naloxone. An additional 11 patients desaturated secondary to partial airway obstruction, which resolved after repositioning the head and neck. Fourteen patients experienced hypotension with fentanyl. All but one returned to baseline blood pressures following an infusion of normal saline. No patient required intubation and no death occurred. Only three patients had recollection of periprocedure events. No patient remembered experiencing pain with the procedure. Hospital stays were not prolonged as a result of the sedation used. In conclusion: (1) deep sedation during EP procedures can be administered safely under the guidance of the electrophysiologist without an anesthetist present; (2) the drugs used should be readily reversible in case of respiratory depression; and (3) this approach may reduce the overall cost of the procedures in the EP lab, maintaining adequate patient comfort.
Iatrogenically Induced Intractable Atrioventricular Reentrant Tachycardia After Verapamil and Catheter Ablation in a Patient with Wolff‐Parkinson‐White Syndrome and Idiopathic Dilated Cardiomyopathy
Authors: NAKAYAMA YASUNORI , KURITA TAKASHI , AIHARA NAOHIKO , KAMAKURA SHIRO , SHIMOMURA KATSURO
Published: July 2006

ln a patient with WPW syndrome and idiopathic dilated cardiomyopathy, intractable atrioventricular reentrant tachycardia (AVRT) was iatrogenically induced. QRS without preexcitation, caused by junctional escape beats after verapamil or unidirectional antegrade block of accessory pathway after catheter ablation, established frequent AVRT attack.
Alternating Current Electrocution Detection and Termination by an Implantable Cardioverter Defibrillator
Authors: MEHDIRAD ALI , LOVE CHARLES , NELSON STEVEN , SCHAAL STEPHEN , COLLINS JANET , HUFFMAN KATHY
Published: July 2006

A patient with an ICD accidentally grasped a power line and was electrocuted. He was unable to release the cable during electrocution though he remained conscious. After receiving a shock from his ICD. the powerline was released. ICD interrogation revealed inappropriate detection of alternating current and delivery of a shock.
Single Pass Lead VDD Pacing in Children and Adolescents
Authors: ROSENHECK SHIMON , ELAMI AMIR , AMIKAM SHLOMO , ERDMAN SHIMSHON , OVSYSHCHER I. ELI
Published: July 2006

Implantation of permanent pacemakers in children and adolescents is possible but usually is limited to single chamber generators. The natural growth of these patients may require physiological pacing, but until recently two leads were required for this type of pacing. The single pass lead VDD pacing mode makes posible physiological pacing by using only one lead, for both atrial sensing and ventricular sensing and pacing. The feasibility of VDD pacing using endocardial lead was evaluated in 16 children and adolescents with congenital or postsurgical atrioventricular block. Their mean age was 7.9 ± 4.9 years (range 1‐16 years) and the smallest patient's weight was 8.2 kg. In all the patients, a single pass pacing lead with atrial sensing rings and bipolar ventricular pacing and sensing capability was implanted through the left or right subclavian vein. The pacemaker generator was implanted in a rectopectoral position. The mean atrial electrogram during the implantation was 4.2 ± 2.1 mV and 2.6 ± 1.9 mV after a mean of 1 week. The ventricular pacing threshold was 0.5 ± 0.2 V; the ventricular pacing impedance was 560 ± 95 Ω and the ventricular electrogram amplitude was 9.9 ± 2.1 mV. This is a first report to demonstrate the feasibility of atrial synchronous ventricular endocardial pacing using a single pass lead in a relatively large group of children and adolescents.
Bedside Autonomic Function Testing in Patients with Vasovagal Syncope
Authors: VAN DEN BERG MAARTEN P. , SMIT ANDRIES J.
Published: July 2006

The factors that determine the individual susceptibility to vasovagal syncope (VVS) are largely unknown, including the role of the autonomic nervous system. We therefore studied common vagal and sympathetic reflexes in 12 patients with WS (mean age 37 (18–75) years, 6 men). The Valsalva maneuver and deep breathing were performed to assess vagal responsiveness and mental arithmetic stress; the cold‐pressor test and isometric handgrip were performed to assess sympathetic responsiveness. Standing up was performed to assess the combined responsiveness. With the exception of a subnormal response to deep breathing in one patient, all vagal tests were normal. In contrast, the response to mental stress, the cold‐pressor test, and isometric handgrip was subnormal in 4 patients, 6 patients, and 4 patients, respectively. The response to standing up was normal in all patients. It is concluded that many patients with WS are characterized by normal vagal responsiveness, but sympathetic hyporesponsiveness. Sympathetic hy‐poresponsiveness might explain the inadequate vasoconstriction, which plays an important, early role in WS.
Electrophysiology of “Incisional” Reentrant Atrial Tachycardia Complicating Surgery for Congenital Heart Disease
Authors: LESH MICHAEL D. , KALMAN JONATHAN M. , SAXON LESLIE A. , DOROSTKAR PARVIN C.
Published: July 2006

Intraatrial reentrant tachycardia, which occurs frequently in patients who have undergone corrective surgery for congenital heart disease, presents a challenge to successful management. Because the surgical repair sites are invariably critical to the development and maintenance of reentrant atrial tachycardia, we use the term “incisional reentry” to describe these arrhythmias. An understanding of the electrophysiology of such “incisional reentry,” and techniques to identify a critical isthmus, are essential for successful ablation of these circuits. A critical isthmus may be identified by the presence of entrainment with concealed fusion. Confirmation that the site is critical to the tachycardia circuit is obtained by an analysis of the relationship between the postpacing interval and the tachycardia cycle length. Advances in mapping from multiple simultaneous sites, along with the ability to create larger, deeper lesions will be needed in order to cure a larger number of these patients. Ultimately, in some cases one must consider each procedure palliative rather than curative, as the disease progresses and substrate evolves and more tachycardia circuits become active.