bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical Evaluation of VDD Pacing with a Unipolar Single‐Pass Lead
Authors: CORNACCHIA DANIELE , FABBRI MAURO , MARESTA ALEARDO , GRASSI GINO , VAIANI PAOLO
Published: July 2006

Twenty patients with advanced AV block and normal sinus node function underwent pacemaker implantation, randomly receiving a CPI 910 ULTRA II model VDD pacemaker. The first 13 patients received the implantation of a single lead with a screw‐in positive ventricular fixation tip and a unipolar ring floating atrial electrode spaced 13 cm from the tip. A subsequent group of seven patients received a conventional porous tinned‐tip lead with a pair of unipolar ring floafing electrodes. The second solution was adopted because the best atrial signal was not always in the high or mid‐high atrium portion, but sometimes in the middle or mid‐low position. With the modified double‐electrode lead, the floating atrial electrode that detects the best signal can be selected, cutting out the pin of the one not used. The comparisons between minimal atrial slew rate and maximal ventricular slew rate, as well as those between minimal P wave amplitude and maximal R wave amplitude, show a highly significant range difference, as large as P < 0.01. Surface electrocardiograms, stress tests, and 24‐hour Holter monitoring showed the correct functioning of the system with an average sensing failure from 0.05 to 1%. In conclusion, VDD stimulation is feasible with a single unipolar lead and a floating atrial electrode in conjunction with a pacemaker generator (CPI 910 ULTRA II) originally designed for permanent twin‐lead implantation.
Our Experience with Spinal Cord Stimulation (SCS) In Peripheral Vascular Disease
Authors: BRACALE G.C. , SELVETELLA L. , MIRABILE F.
Published: July 2006

Spinal cord stimulation (SCS) by epidural electrodes is being used more often in the treatment of patients with severe intractable ischemic pain. The promising clinical results and the objective increase in lower extremity blood flow (plethysmography, thelethermography, etc.), suggests that spinal cord stimulation may have an important role in the management of advanced arterial disease when other forms of treatment have failed. The selection criteria for implantation of SCS are very important. Our indications in patients with peripheral vascular disease are: 1. Peripheral vascular disease with severe, intractable symptoms that are untreatable by medical or surgical therapy. 2. Inflammatory or diabetic arterial disease resistant to medical treatment and/or sympathectomy. 3. Persistent and severe ischemic pain and/or ulcers in patients with patent grafts. 4. Patients for lumbar sympathectomy who have a high myocardial risk. Contraindications to implantation of SCS are claudication intermittent, large necrotic lesions (gan‐grene) and patients who have undergone prolonged narcotic therapy.
Spinal Cord Stimulation (SCS) in Peripheral Ischemic Pain
Authors: FIUME D. , PALOMBI M. , SCIASSA V. , TAMORRI M.
Published: July 2006

Between 1982 and 1987,45 patients suffering from painful symptomatology caused by peripheral vascular disease, not curable by medical or surgical therapy, were implanted with epidural neurological stimulators. Measurements used in evaluating the effectiveness of the method were pain control, walking distance, and development of trophic problems. With most patients, we noted a satisfactory and long‐lasting degree of pain control. Walking distance increased to a surprising degree. Trophic lesions smaller than 3 sq cm healed, while lesions of greater size required amputation of the limb. Transcutaneous oxygen tension (TcpO2) was used to study the efects of SCS on peripheral circulation in implanted patients. In addition, TcpO2 was calculated in 15 patients before and during the percutaneous test to predict the efectiveness of SCS. Regression of painful symptomatology was achieved only in patients whose TcpO2b improved during the course of the testing. Therefore, this method provides an objective measure for the implantation of a neurostimulator
Epidural Spinal Electrostimulatory System (ESES) in the Management of Diabetic Foot and Peripheral Arteriopathies
Authors: FRANZETTI IVANO , DE NALE ANGELO , BOSSI ANTONIO , GRECO MARCO , MORRICONE LELIO , RUGGERINI MANUELA , MEAZZA DANIELE , SCIOLLA ANDREA , CAVIEZEL FRANCESCO , ORIANI GIORGIO
Published: July 2006

Epidural spinal electrostimulatory system (ESES) or dorsal column stimulation (DCS) may be used for the treatment of peripheral vascular diseases of the lower extremities. ESES has been used in our metabolic and surgical department as a way to ameliorate inadequate blood supply in patients suffering from diabetic foot (seven patients), painful chronic arterial narrowing, or inoperable occlusions (25 patients). The continuous stimulation by an implantable apparatus (Medtronic model Itrel, Medtronic, Inc., Minneapolis, MN, USA) led to a reduction or disappearance of pain, an improvement in plethysmographic curves, functional performance, and trophic lesions in about 75% of the patients. The system is safe and well‐tolerated by patients.
Epidural Neurostimulation in the Treatment of Frostbite
Authors: ARREGUI R. , MORANDEIRA J.R. , MARTINEZ G. , GOMEZ A. , CALATAYUD V.
Published: July 2006

Epidural spinal cord stimulation (SCS) and conventional treatment produced good therapeutic effects in four young patients with frostbite of the lower limbs. The mechanism of action is unknown but the treatment resulted in rapid recovery with reduced pain and a more peripheral level of amputation. These preliminary results warrant further studies of SCS in the treatment of frostbite.
Beneficial Effects of Cervical Spinal Cord Stimulation (cSCS) on Patients with Impaired Consciousness: A Preliminary Report
Authors: MATSUI TORU , ASANO TAKAO , TAKAKURA KINTOMO , YAMADA RYOUZOU , HOSOBUCHI YOSHIO
Published: July 2006

Electrical stimulation of the spinal cord can be used for treatment of intractabie pain and spasticity. Based on our experimental findings cervical spinal cord stimulation (cSCS) was performed on eight patients with severe brain dysfunction due to traffic accidents, pronounced vasospasm caused by subarachnoid hemorrhage or surgery of huge cerebral tumors (chordoma). After a 1 to 2 month period of stimulation, two patients became conscious and began to speak. It remains unclear whether cSCS induced the restoration of consciousness and improved neurological deficits. Although the successful results might be due to chance, cSCS might have stimulated brain function. This preliminary report shows such excellent results that further studies are warranted.
The Effects of Cervical Spinal Cord Stimulation (cSCS) on Experimental Stroke
Authors: MATSUI TORU , HOSOBUCHI YOSHIO
Published: July 2006

Cervical spinal cord stimulation (cSCS) has been employed as a treatment for intractable pain for the past 20 years. Recently, we reported that cSCS increased regional cerebral blood flow (rCBF) in cats and humans. The present study was designed to examine the effects of cSCS on experimental cerebral strokes, using a cat middle cerebral artery occlusion model (MCAO). A total of 31 cats were randomly assigned to three groups; Group 1: control. Group 2: sham operation, Group 3: cSCS. Mortality of the control group was 92% as long as 4 days after MCAO. Groups 2 and 3 showed a prolongation of survival rate (44% and 56%, respectively). CSCS reduced the rate of death within 24 hours after MGAO. There was no alteration of infarct size, which was estimated by the TTC method and measured by computer technique (PDP‐11/23), was found in dead cats of all groups. In cats that survived in Group 3, however, drastic prevention of an infarct progression was found, compared to Group 2. The results provide a ciinical application of cSCS for stroke patients, although no evident mechanism was obtained.
Spinal Cord Stimulation (SCS) in Spastic Hemiparesis
Authors: CIONI B. , MEGLIO M. , PREZIOSO A. , TALAMONTI G. , TIRENDI M.
Published: July 2006

Thirteen patients with post‐stroke spastic hemiparesis underwent a percutaneous test trial of spinal cord stimulation (SCS) in order to modify their motor disturbances. Clinical evaluation based on Albert's motor scale and neurophysiologcial evaluation consisting of surface EMG during voluntary, involuntary, and reflex motor activity were performed before and during SCS. At the end of the test period, eight patients showed a significant improvement in their motor performance. The EMG analysis confirmed the clinical data. SCS was followed by a reduction or disappearance of synergic coactivation with better agonist‐antagonist coordination, a decrease of clonus both in duration and spreading, and better endurance. The effect on motor controi did not increase with time after the first month of SCS, but was long lasting (mean follow‐up: 2 years). There was a correlation between sensory deficit and motor outcome suggesting that the enhancement of sensory input put into play by SCS and the consequent development of new sensory‐motor integration might be responsible for the improvement in motor performance.
Cough Syncope Caused by Sinus Arrest in a Patient with Sick Sinus Syndrome
Authors: CHOI YUN SHIK , KIM JAE JOONG , OH BYUNG HUI , PARK YOUNG BAE , DON SEO JUNG , LEE YOUNG WOO
Published: July 2006

Cough syncope is a syndrome in which dizziness or syncope occurs after prolonged bouts of cough. This paper presents a case of 63‐year‐old man with recurrent dizziness and syncope. The 24‐hour ambulatory electrocardiogram and intracardiac electrogram showed sinus node dysfunction with sinas arrest, both spontaneous and inducible by voluntary cough. Sinus arrest was sometimes associated with dizziness. A permanent WI pacemaker was implanted and no further cough syncope has occurred. We suggest that sinus arrest may play a role as a mechanism of cough syncope in a patient with sick sinus syndrome.
Percutaneous Nd:YAG Laser Coagulation of Ventricular Myocardium in Dogs Using a Special Electrode Laser Catheter
Authors: WEBER HELMUT , ENDERS SUSANNE , KEIDITISCH ERNST
Published: July 2006

A novel catheter system was used for intracardiac electrogram recordings, ventricular pacing and continuous‐wave Nd:YAG laser (1,064 nm) irradiation 0f ventricular myocardium in eight dogs. Radiation at a power of 10 W for 3, 5, and 10 seconds was delivered through a 400 μ optical fiber. Power density was 15 W/mm2. A total of 96 laser injuries (12 per dog) were produced in selected sites in both the right and the left normal canine ventricle. Ventricuiar arrhythmias were noted during 12 of 96 (12.5%) laser pulses. Programmed electrical stimulation performed during control study immediately (all dogs) at 2 days (two dogs), and 4 months (4 dogs) following the experiments showed no episodes of sustained or nonsustained ventricular tachycardia. Radiation energies up to 50 J (10 W over 5 s) caused focal injuries of homogeneous coagulation/fibrosis localized to the target area, without vaporizing tissue and forming craters. Morphometrically and histologically there was a direct relationship between the energy of radiation delivered, and the extent and severity of the injury produced. The maximum size of lesions measured 7/11 mm (diameter/depth). Using a special catheter system laser coogulation of myocardium can be accomplished percutaneously. This method can create controlled subendocardial injuries without major side effects and appears to overcome most disadvantages of transcatheter high energy direct‐current shocks when used as a regular course of procedure in ablation of arrhythmogenic tissue in the heart.
Ablation of Ventricular Tachycardia of Right Ventricular Origin with Low Energy Shocks
Authors: JORDAENS LUC , ROELANDT RAF , PALMER ALBERT , VAN WASSENHOVE ETIENNE , CLEMENT DENIS
Published: July 2006

Three shocks of 2 joules (2.000 volts within 0.3 msec) were given to a patient with ventricuiar tachycardia of right ventricuiar origin at the site of the earliest activation. A standard 6 Fr USCI mapping catheter was used. After the first shock the cycle length prolonged from 385 to 531 msec. After the second shock, the tachycardia was no longer inducible and it remained so after 1 week. No recurrences were seen during a follow‐up period of 8 months. This is the first report demonstrating efficacy of modified low energy shocks for ventricular tachycardia.
Impedance to Transesophageal Atrial Pacing: Significance Regarding Power Sources
Authors: KERR CHARLES R. , CHUNG DAVID C. , WICKHAM GRAHAM , JAMESON MICHAEL , VORDERBRUGCE SHIRLEY
Published: July 2006

Transesophageal stimulation is an expeditious method of atrial pacing. Using pulse widths of 10 msec results in reduction of current requirement to values that are usually less than 15 mA. An unknown variable in transesophageal atrial pacing has been impedance. In this study, we investigated the impedance to transesophageal atrial pacing in ten patients using a stimulator with a 63 V power source capable of delivering constant current to 20 mA against an impedance of 2,000 ohms. A bipolar electrode was used to deliver stimuli with a current of 15 mA. Voltage across a known resistance and current were measured on an oscilloscope and the impedance was calculated. Pacing thresholds were also performed and ranged from 6.2 to 16.5 mA (mean 9.4 ± 2.9 mA, SD). Impedance varied between 720 and 2,670 ohms (mean 1,750 ± 540 ohms). The stimulator used to measure impedance in man and two other commercially available stimulators were bench tested against known resistances of 500 to 2,000 ohms. The other stimulators with power sources of 12.5 and 35 V had attenuation of the delivered current at resistances of between 1,000 and 2,000 ohms. Thus, this study has demonstrated that transesophageal atrial pacing incurs impedances two to five limes greater than incurred with intracardiac pacing leads. Therefore stimulators with high power sources are required to deliver the programmed current against these impedances.
‘Long‐Term Results of Antitachycardia Pacing in Patients with Supraventricular Tachycardia
Authors: SCHNITTGER INGELA , LEE JOHN T. , HARGIS JANE , WYNDHAM CHRISTOPHER R.G. , ECHT DEBRA S. , SWERDLOW. CHARLES D. , GRIFFIN JERRY C.
Published: July 2006

Between 1979 and 1984 the Cybertach‐60, (Intermedics, Inc. Model 262–01), a programmable, automatic antitachycardia pacemaker was implanted in 11 patients who had drug‐refractory supraventricular tachycardia (SVT). The patients have been followed for a total of 64–108 (mean 84 months). All patients were symptomatic and had failed two or more drugs and six patients had required prior DC cardioversion. The mechanism of supraventricular tachycardia was atrioventricular (AV) nodal reentry in six patients, AV reentry in four patients, and atrial tachycardia in one patient. Preoperatively all patients had reliable termination of the tachycardia without induction of atrial fibrillation by pacing methods available to Cybertach‐60. Postimplant, Cybertach‐60 reliably terminated all episodes of tachycardia without ancillary drug therapy. Nevertheless, at long‐term follow‐up antitachycardia pacing was effective and safe in the minority (36%). with only four patients out of eleven still using a pacemaker for supraventricular tachycardia. One of these four patients required additional drug therapy. In one of the patients, the Cybertach‐60 was replaced after 78 months by a more advanced device, (Intertach, Intermedics, Inc.) because of a depleted Cybertach‐60 battery. In seven patients who no longer use antitachycardia pacing for termination of tachycardia, one patient developed atrial fibrillation during tachycardia termination (at 58 months postimplant). Three patients experienced induction of tachycardia or atrial fibrillation by the pacemaker due to undersensing of sinus P waves (at 36, 48, and 51 months). One patient had inappropriate rate detection while in sinus rhythm triggering the tachycardia termination burst from the pacemaker and subsequent SVT induction. Although pace termination of supraventricular tachycardia was effective in two patients, they chose elective ablation (AV nodal and accessory pathway, respectively, at 74 and 6 months) due to frequent symptomatic SVT.
Pacemaker Electrode Repositioning Using the Loop‐Snare Technique
Authors: MORRIS D. CHRISTOPHER , SCOTT IAN R. , JAMIESON W.R. ERIC
Published: July 2006

Using a percutaneous femoral vein approach under fluoroscopic control, a malpositioned ventricular pacemaker electrode was released from the right ventricular vvall by hooking the lead with a deflecting wire inserted into a RIM catheter. A closed loop was formed by tightening the handle of the wire allowing the electrode to be dislodged and pulled into the inferior vena cava. The electrode was then snared using a loop formed hy an exchange wire advanced through an 8 French catheter with a J‐curve steamed at its tip. The electrode was advanced to the right ventricular apex and released by advancing one end of the snare wire while pulling the other end to open the loop.
Myopotential Interference in Unipolar Rate Responsive Pacemakers
Authors: LAU CHU‐PAK , LINKER NICHOLAS J. , BUTROUS GHAZWAN S. , WARD DAVID E. , CAMM A. JOHN
Published: July 2006

The effects of myopotential interference on unipolar rate responsive pacemakers were assessed in 22 patients. Six types of pacemakers (from four manufacturers) were studied: five TX2 (QT sensing), seven Biorate (five RDP3 and two MB‐1, respiratory rate sensing), seven Adivitrax (activity sensing), two Medtronic 2503 (dP/dt sensing), and one Sensolog P703 (activity sensing). Provocative tests using arm exercises were performed in both VVI and rate responsive modes. At nominal sensitivity settings (1.8–2.5 mV), 55% of these patients were myopotential positive for at least 1 provocative test. Pressing the palms together was found to be the most sensitive provocative test Rate response was achieved with treadmill exercise (all patients), hyperventilation (RDP3 and MB‐1) and tapping (Activitrax) or wobbling the pacemaker in its pocket (Sensolog). During continued rate acceleration, myopotential interference was induced by arm exercises. The duration of inhibition was shorter when the provocative tests were performed during rate response compared to that occurred at rest. Short periods of myopotential interference resulted in temporary inhibition of pacing but rate response continued immediately on removal of the interference. In one patient with a RDP3 pacemaker, a prolonged episode of myopotential interference during treadmill exercise resulted in reversion of the pacemaker to the interference mode. Appropriate adjustment of the sensitivity setting effectively controlled the symptoms in most patients. However, one patient with a QT sensing pacemaker and symptomatic myopotential interference required programming to the VVT pacing mode. Two out of five patients with RDP3 required pacemaker replacement because of uncontrolled myopotential interference. In conclusion, myopotential interference is a significant problem in unipolar rate responsive pacemakers. The use of provocative tests may assist in the diagnosis of this problem.
The Response of Digitalized Canine Ventricle to Programmed Stimulation: A Study on Triggered Activity Arrhythmias in the Whole Heart
Authors: IINUMA HIROYUKI , SEKIGUCHI AKIKO , KATO KAZUZO
Published: July 2006

Triggered activity (TA) has recently received increased attention as a mechanism responsible for cardiac arrhythmias. However, few studies have shown TA in the intact heart. In an ouabain‐treated dog's heart we have shown: (a) overdrive acceleration, (b) a concordant relationship between the postpacing interval (PI) and pacing cycle length (CL), and (c) a discordant relationship between the PI and number of paced beats necessary to induce TA. These findings appeor to agree with the distinctive characteristics of TA arrhythmias elucidated in previous in vitro studies and suggest TA rather than a reentrant tachycardia. In addition, it is possible that this heart preparation could be considered as a suitable model for the study of TA arrhythmias. These results were obtained using a programmed stimulation protocol in this dog model: (1) Following single programmed ventricular stimulation during sinus rhythm, a repetitive ventricular response (RVR) of more than 3 beats occurred in only 20% of hearts. The relationship between PI and the coupling interval (CI) of the extrastimulus was concordant in 80% (12/15) and discordant in 13% (2/15) of all experiments. The Pl‐CI relationship was influenced by the mutual relationship between the stimulating, recording, and originating sites of TA. (2) RVR of more than 3 beats was induced by consecutive overdrive ventricular stimulation during sinus rhythm (78%). In addition, the PI‐pacing CL relationship was concordant (100%). (3) The transient termination of sustoined VT that occurred spontaneously after administration of a large dose of ouabain was seen in only 15% of the cases after a single programmed premature ventricular stimulation. The return cycle‐CI relationship was biphasic in 75% (15/20) experiments and discordant in 25% (5/20) of the experiments. (4) The termination of spontaneous sustained VT by overdrive ventricular stimulation occurred in only 8% of the cases. Transient overdrive acceleration of VT occurred after overdrive pacing (53%). In contrast, overdrive suppression occurred in only 13%. Thus, the characteristics of TA arrhythmias observed in the whole heart preparations differed, in some respects, from those obtained by in vitro studies. These quantitative observations could suggest a differentiation, based on probability, between TA and the reentrant mechanism that would respond to programmed stimulation in a similar manner. The differentiation between reentrant and triggered ventricular tachycardia can be made with reasonable assurance using these programmed stimulation techniques.
Active Fixation Atrial Leads: Randomized Comparison of Two Lead Designs
Authors: KAY G. NEAL , ANDERSON KEVIN , EPSTEIN ANDREW E. , PLUMB VANCE J.
Published: July 2006

Active fixation leads have reduced the incidence of lead dislodgement in patients with permanent pacemakers. However, theoretic concern that the tissue trauma associated with a myocardial screw‐helix may increase the chronic pacing threshold of active compared to passive fixation leads has remained. Whether active fixation leads with a stimulating electrode that is independent of the fixation mechanism are associated with a lower chronic pacing threshold than leads utilizing a screw‐helix for both fixation and stimulation is unknown. The present prospective, randomized study compared the acute and chronic atrial pacing and sensing characteristics of two unipolar active fixation leads, one utilizing a screw‐helix for both fixation and electrical stimulation, the other with an active porous tip electrode and an electrically inactive helix. Patients were randomized to receive either a Medtronic 6957J lead with an electrically active myocardial screw‐helix or a Cordis 329–101P lead with an inactive helix and a porous tip electrode. The baseline characteristics of the groups were comparable. At implantation, the 329–101P lead had a lower mean voltage threshold than the 6957J lead (0.61 ± 0.16 Vvs 1.05 ± 0.34 V, P = 0.0004). There were no significant differences in atrial electrogram amplitude, slew rate, or lead impedance between the groups. At 6 weeks follow‐up, there were no differences in the mean threshold voltage (1.85 ± 0.36 vs 1.93 ± 0.69 V), impedance (528 ± 81 vs 530 ± 118 ohms), or atriol electrogram amplitude (2.63 ± 0.50 vs 2.42 ± 0.95 mV) between the two leads. At long‐term follow‐up (mean 16.2 ± 2.8 months, range 13.1–20.0 months) there were no significant differences in voltage threshoid (1.65 ± 0.61 vs 1.97 ± 0.64 V), impedance (565.5 ± 81.6 vs 617.7 ± 146.7 ohms), or atrial eiectrogram amplitude (2.79 ± 0.75 vs 3.10 ± 1.53 mV). Thus, these results suggest that active fixation leads in the atrium with an electrode that is independent of the fixation mechanism do not provide chronic stimulation thresholds or electrogram amplitudes that are superior to those obtained with leads utilizing a myocardial screw‐helix as both the active electrode and the fixation device.
Double Atrial and Double Ventricular Responses During Slow‐Fast Fast‐Slow Atrioventricular Nodal Reentrant Tachycardia
Authors: MATSUHISA MOKUO , SHIMOMURA KATSURO , OHE TOHRU , KAMAKURA SHIRO , AIHARA NAOHIKO
Published: July 2006

A case was described with fast‐slow form of atrioventricular nodal reentrant tachycardia as related with simultaneous fast and slow pathway conduction both antegrade and retrograde. Fast‐slow form of tachycardia was induced by premature right atrial stimulation or incremental right ventricular pacing when the last paced beat conducted to the atria via both fast and slow pathways of the atrioventricular node causing double atrial response. Fast‐slow form of tachycardia was spontaneously shifted to slow‐fast form when the atrial echo, possibly through the retrograde intermediate pathway, was conducted antegradely over the fast and slow pathways simultaneously, producing double ventricuiar response.
Permanent Antitachycardia Pacemaker Therapy for Ventricular Tachycardia
Authors: NEWMAN DAVID M. , LEE MICHAEL A. , HERRE JOHN M. , LANGBERG JONATHAN J. , SCHEINMAN MELVIN M. , GRIFFIN JERRY C.
Published: July 2006

This article describes our experience with an antitachycardia pacemaker alone (N = 3) or in combination with an automatic implontoble cardioverter defibrillator (AICD, N = 8) in the treatment of ventricular tochycardia. EJeven patients (mean ejection fraction 31%, mean oge 67 years) received an antitachycardia pacemaker. Nine had their units programmed for automatic antitachycardia pacing, one unit was programmed to automatic antitachycardia pacing by magnet activation only, and one to tachycardia detection and bradycardia support. Of the nine patients with automatic antitachycardia pacing, seven received appropriate and successful pace termination of spontaneous ventricular tachycardia at up to 120 times per month. Eight of these nine have had AICD implantations as well. There were no operative complications. Over a mean (± SD) follow‐up of 12.1 ± 9.3 months (range 3–29 months), there have been two deaths, both due to heart failure. There have been four AICD discharges in three patients. Two units discharged in a clinically appropriate setting. The other two units, both with rate cutoffs <200 beats/min, were inadvertently triggered by the antitachycardia pacemaker and/or the underlying rate. In addition to the careful selection of the defibrillator rate cutoff, adverse device‐device interactions were avoided by careful intraoperative lead positioning, and the disabling of bradycardia pacing when not needed or contraindicated. Antitachycardia pacing, with the safety provided by the AICD, is an effective treatment for patients with medically refractory ventricular tachycardia.
A Clinical Study of the Dynamics of Parasystole
Authors: GORDON DAVID , SCAGLIOTTI DANIEL , COURTEMANCHE MARC , GLASS LEON
Published: July 2006

A mathematical model for pure parasystole ond modulated parasystole leads to a number of quantitative predictions. The predictive power of the model is examined by confronting it with data obtained from a 16‐year‐oId symptomatic male born with a ventricular septal defect that was surgically closed at 5 years of age. A diagnosis of ventricular parasystole and inducible ventricular tachycardia was made following a syncopal episode. The physiological variables required by the model to make specific predictions are the sinus and ectopic cycle lengths and the ventricular refractory period. From these three variables, a two‐dimensional parameter space is constructed consisting of the ratio of the refractory period to the sinus cycle length and the ratio of the ectopic to sinus cycle length. For any set of parameters, predictions are made concerning the number of sinus beats between ectopic beats. The different behaviors exhibited in the electrocardiographic (ECG) data agree with theoretical predictions.
Do Electrode and Lead Design Differences for Permanent Cardiac Pacing Translate into Clinically Demonstrable Differences? (Comparison of Sintered Platinum and Activated Vitreous and Porous Carbon Electrodes)
Authors: BOURKE JOHN P. , HOWELL LYNNE , MURRAY ALAN , HILL WILLIAM E. , COWAN J. CAMPBELL , BEATT KEVIN , ERRINCTON JOAN , JAMESON STUART , GOLD RONALD G.
Published: July 2006

A randomized prospective study was undertaken to compare the electrical performances of three permanent, endocardial, tined pacing leads with different electrode designs—sintered platinum, vitreous carbon, and porous carbon. Ninety‐nine patients received one of the leads (S80 31; 423S 32; S100 36). Acute R wave amplitude and ST elevation of ihe native endocardiai electrogram, voltage threshold, impedance, and current flow at four pulse durations (0.25–1.0 msec) were measured. Voltage thresholds were measured noninvasively at each of four pulse durations at 2 days and 1, 3, and 6 months after implantation. No significant differences were found in sensing properties, or current flow at threshold at 0.5 msec pulse duration. The 423S lead had a significantly higher impedance at threshold and both a higher impedance and lower current flow at 5 V. No significant differences in threshold voltages were found between the three leads at any pulse duration, at any of the assessed times after implantation. Six‐month thresholds for the S80, 423S, and S100 leads were 1.18 ± 0.35, 1.17 ± 0.29, and 1.06 ± 0.38 V respectively at 0.5 msec pulse duration. Differences between ‘high performance’ pacing leads need to be of a greater order of magnitude before they can be exploited to give any real clinicai advantage to patients.
Fascicular Parasystole Associated with Tachycardia‐Dependent Right Bundle Branch Block
Authors: HIRAI JUN‐ICHI , NISHIMURA MASAO , MATOBA MUNETOSHI , AKASHI YOSHIHIRO , SAGA TAKASHI , WATANABE YOSHIO
Published: July 2006

A 43‐year‐old female with a chief complaint of palpitation was subjected to clinical electrophysiological studies. Initial standard 12‐lead ECG revealed that her palpitation tvas caused by fascicular parasystole firing at the basic cycle length of 1.25–1.40 seconds, and that both sinus and parasystolic beats were associated with left anterior fascicular block and tachycardia‐dependent RBBB. His‐bundle electrocardiogram suggested that the parasystolic focus was located in the proximal portion of the anterior fascicle of the left bundle branch and that the site of tachycardia‐dependent conduction block was located in the main right bundle branch. These findings suggest that diffuse pathological changes in the intraventricular conducting system were responsible for both the conduction block and automatic impulse formation in the present case.
Initial Clinical Experience with a Rate Responsive Pacemaker
Authors: SINGER IGOR , OLASH JEANNE , BRENNAN A. FRANGES , KUPERSMITH JOEL
Published: July 2006

Prism‐CLR is a new single chamber unipolar pace, bipolar or unipolar sense, rate responsive pacemaker that utilizes a closed‐loop system based on the analysis of the evoked potential for rate adjustment It also has an automatic output regulation feature for capture verification and threshold search. Five patients in whom this pace maker was implanted exhibited an appropriate rate increase with exercise and psychological stress. Automatic output regulation functioned appropriately in three of five patients. Preliminary data suggest that Prism‐ClR is an elective pacemaker for patients who may benefit from rate responsive pacing. The automatic output regulation recognition algorithm may need modification in some patients.
Actuarial Incidence and Pattern of Occurrence of Shocks Following Implantation of the Automatic Implantable Cardioverter Defibrillator
Authors: FOGOROS RICHARD N. , ELSON JAMES J. , BONNET CHRISTOPHER A.
Published: July 2006

The actuarial incidence and pattern of occurrence of shocks were analyzed in 65 patients after implantation of the automatic imptantable cardioverter defibrillator. During a mean follow‐up of 25 ± 21 months only one patient died suddenly, and this patient had a nonfunctioning device at the time of death. The long‐term actuarial risk of death from any cause in the patients who received appropriate shocks was not significantly different than for the entire group. The 1‐ and 4‐year cumulative risk of receiving any shock was 51 ± 7% and 81 ± 11%; of receiving an appropriate shock was 33 ± 7% and 64 ± 10%; of receiving a spurious shock was 17 ± 5% and 21 ± 6%; and of receiving an “indeterminate” shock was 19 ± 6% and 52 ± 10%. In 14 patients who were followed for 24 months without receiving an appropriate shock, the actuarial risk of receiving an appropriate shock was 29 ± 14% during the next 24 months. The mean number of shocks delivered during appropriate episodes was 1.6 ± 0.9, which was significantly lower than the mean of 4.0 ± 2.0 shocks during spurious episodes (P < 0.02). The mean number of shocks during indeterminate episodes was 1.7 ± 1.5. Our data confirms the efficacy of the implantable defibrillator in preventing sudden death. The majority of patients with this device receive appropriate shocks during long‐term follow‐up, and the cumulative incidence of appropriate shocks increases steadily for at least 4 years. In contrast, the cumulative incidence of spurious shocks plateaus at about 12 months. Our data suggests that many “indeterminate” shocks actually appear to be appropriate.
A Transarterial Approach of Electrical Ablation of Atrioventricular Junction in a Dog Model: Comparison of the Effects between High and Low Energy Shocks
Authors: MOROE KAZUO , HIROKI TADAYUKI , OKABE MASANORI , SASAKI YASUSHI , FUKUDA KEISUKE , ARAKAWA KIKUO
Published: July 2006

To analyze the effective ness of a ctransarterial catheter technique for electrical ablation of the atrioventricular junction, 30 mongrel dogs were studied by means of synchronized electrical shock between the catheter adjacent to the noncoronary cusp and a metal plate behind the dog's back using a standard cardioversion unit. These dogs were classified into two groups according to the energy delivered. The high energy group received more than 100 joules (group A) and the low energy group received from 20 to 60 joules (group B). Complete atrioventricular block was induced by a single shock in all dogs. In group A, ventricular premature beats appeared in all dogs; ventricular fibrillation and ventricular tachycardia appeared immediately in half (6/12) after electrical ablation. No ventricular dysrhythmios occurred in group B. Temporary right ventricular pacing was also performed in 10 out of 12 dogs in group A after electrical ablation. In contrast only one dog required pacing in group B. The cycle length of the subsidiary pacemaker rhythm was essentially identical in both groups. The QRS duration of the subsidiary pacemaker rhythm in group A was significantly longer in group B (P < 0.01). The extent of myocardial damage induced by electrical ablation in group B was more localized than those in group A. However, the histological lesion representing the granulation tissue with necrosis and slight chronic inflammatory cell infiltration, was identical between both groups A and B. It was concluded that this technique of low energy electrical ablation of the atrioventricular junction adjacent to the noncoronary cusp via a transarterial approach was useful in producing an experimental model of chronic complete AV block.
The Effect of an Entrainment Protocol on Ouabain‐Induced Ventricular Tachycardia
Authors: VOS MARC A. , GORGELS ANTON P.M. , LEUNISSEN‐BEEKMAN JET D.M. , BRUGADA PEDRO , WELLENS HEIN J.J.
Published: July 2006

Overdrive stimulation of reentrant ventricular tachycardias (VT) may result in entrainment and/or termination of these arrhythmias. We investigated whether surface ECG criteria of entrainment can also be observed in nonreentrant VT. For this purpose ouabain‐induced tachycardias were used that are considered to be based on delayed afterdepolarizations. In nine conscious dogs, having surgically induced complete AV block, pacing was performed using trains of 20 stimuli from a site distant to the origin of the VT. The pacing intervals were shortened in steps of 5–10 msec, until complete capture from the pacing site or termination of the VT was obtained. During stimulation variable fusion was seen and complete capture of the ventricles from the pacing site occurred just after a slight decrease in pacing cycle length (20 ± 10 msec). Overdrive stimulation resulted only in 1 out of 58 stimulation trains in termination of VT. Following stimulation it was observed that: (1) The length of the first postpacing interval was significantly longer (P < 0.001) than both the mean prepacing VT cycle length and interstimulus interval; (2) A change in QRS configuration occurred after 57% of the stimulation trains; (3) The VT accelerated slightly in comparison to the prepacing rate (P < 0.05); and (4) The length of the first postpacing interval and the mean R‐R interval of the VT postpacing were directly related to the interstimulus interval (r = 0.82 and 0.97, respectively). In conclusion, overdrive stimulation of ouabain‐induced arrhythmias did not result in entrainment or in termination of the tachycardia. Instead, other responses were seen that may be of help in differentiating between arrhythmias caused by delayed after depolarizations and reentry.
Determinants of Impedance Rise During Catheter Ablation of Bovine Myocardium with Radiofrequency Energy
Authors: RING MICHAEL E. , HUANG SHOEI K. STEPHEN , GORMAN GRACE , GRAHAM ANNA R.
Published: July 2006

Recently, radiofrequency (RF) energy has been used as an alternative energy source to direct‐current (DC) electricity for catheter ablation of recurrent tachyarrhythmias. Since delivered energy is inversely related to impedance, factors that cause impedance rise during catheter ablation impede the ability to ablate tissue. To elucidate some of the factors responsible for impedance rise during RF (750 kHz) catheter ablation using a constant voltage RF generator, the effects of the following variables on impedance were studied in an in vitro bovine heart model: power setting (10–70 W), pulse duration (10–60 sec), catheter contact pressure (5‐1 20 gm), repeated applications (2–4), and immersion media (saline vs citrated blood). Baseline impedance in blood was twice that of saline (190 vs 80 ohm) and rises in impedances occurred more rapidly in blood for the same energy settings. Increased power settings (≥ 30 W) and pulse duration (≥ 30 sec at 20 W) were associated with impedance rises in blood medium. Typically, impedance rises in blood were associated with blood coagulum on the catheter electrodes. Impedance rises in both saline and blood media were also associated with tissue charring and endocardial surface disruption. Once a rise in impedance occurred at the ablation site, repeated applications to the same site resulted in a more rapid rise in impedance. Catheter contact pressure of 80 gm or more also resulted in rapid impedance rise. These data suggest that factors other than set power and duration may also contribute to impedance rises during RF ablation. These Endings may have important clinical implications in performing catheter ablation with RF energy.
A Comparative Evaluation of a Minute Ventilation Sensing and Activity Sensing Adaptive‐Rate Pacemakers During Daily Activities
Authors: LAU CHU‐PAK , WONG CHEUK‐KIT , LEUNG WING‐HUNG , CHENG CHUN‐HO , LO CHI‐WING
Published: July 2006

Most studies evaluating the rate response of adaptive‐rate pacemakers have been based on treadmill or bicycle exercise. These studies disregard the fact that few pacemaker recipients voluntarily undertake such activities. The rate responses of nine patients (mean age 62 years, range 33 79 years) with implanted minute ventilation sensing (Meta) pacemakers were studied. The indications for pacing were complete heart block (seven patients), six sinus syndrome (one patient), and five nodal disease (one patient). Significant improvement in maximum distance covered during a 12‐minute walking test was observed in the rate adaptive compared to the VVI pacing mode (989 ± 104 vs 921 ± 90 m. P < 0.02). The rate responses of this pacemaker during daily activities were recorded with telemetry during a variety of structured daily activities. The rate responses were also compared to those of an externally attached Activitrax pacemaker in each patient and to a group of ten age and sex matched volunteers. For less strenuous activities such as walking, descending stairs, washing, and bed making, both pacemakers achieved adequate rate responses compared to normal subjects. For more strenuous activities, the Activitrax pacemaker failed to achieve an adequate rate response. For example. the pacing rate achieved on ascending stairs was lower than that achieved on descending stairs (92 ± 3 vs 102 ± 3 bpm, P < 0.02). The direction of rate responses was more appropriate for the Meta pacemaker. Similar to the normal subjects, the maximum rate was reached before the end of an activity with the Activitrax pacemaker. A significant delay was observed with the Meta pacemaker and the rate response was achieved during the recovery period of some activities (e.g., maximum pacing rate was achieved at 45 ± 35 sec after ascending stairs with the Meta pacemaker). In conclusion, the Meta pacemaker improved submaximal exercise capacity. This study suggests the two different rate adaptive pacemakers differed in their proportionality and speed of rate responses.
Catheter Ablation Without Fulguration: Design and Performance of a New System
Authors: AHSAN ARIF J. , CUNNINGHAM DAVID , ROWLAND EDWARD , RICKARDS ANTHONY F.
Published: July 2006

A new system is described for catheter ablation which comprises a short time capacifive power source and a specially designed catheter. The aim of the new system is to deliver high voltages with minimal or no arcing and thus avoid the risks associated with barotrauma. The performance of the new system was compared in a saline tank with that of the conventional system. The new system allowed significant increases in delivered voJtage, current and energy without arcing. This new system shouJd allow safer catheter ablation.
Programming Eccentricities of an Activity Sensing Pacemaker
Authors: LEMAN ROBERT B. , MCVENES* RICK D. , KRATZ N M. , GILLETTE PAUL C.
Published: July 2006

The Activitrax rate responsive pacemaker system has enjoyed wide popularity but minor engineering eccentricities have occurred and have been reported. We report another unusual feature seen in Activitrax models 8400, 8402, and 8403. This feature consists of continuing in a temporary mode while a different permanent mode was programmed. These eccentricities of the programming features are not very commonly seen, however, they can be some what perplexing to the physician following the patient. These unusual features are no longer present in the newer models being manufactured.
DSA Diagnosis of Pulmonary Embolization from Intracardial Thrombus in a Patient with Permanent Pacing Catheter
Authors: NEUWIRTH JIŘÍ , BOHUTOVÁ JOSEFA , KOLÁŘ JAROMÍR , KAUTZNER JAN , NOVÁK MILOŠ
Published: July 2006

Pulmonary embolization in patients with implanted pacemakers is rare and an intracardiac thrombus attached to the distal end of a newly implanted ventricular endocardial electrode following removal of a previously implanted lead is a curiosity. We have documented such a case by digital subtraction angiography, a minimally invasive procedure that demonstrates both an intracardiac thrombus and secondary pulmonary embolization in a single procedure, which also allows simplified follow‐up evaluation following therapy.
Quantitative Analysis of Contribution of Rate Response in Three Different Ventricular Rate Responsive Pacemakers During Out of Hospital Activity
Authors: SULKE NEIL , PIPILIS ATHANASE , BUCKNALL CLIFFORD , SOWTON EDGAR
Published: July 2006

The contribution of rate response provided by three different types of rate responsive pacemaker (Sensolog, Meta, and Vitatron TX) was assessed in 25 patients during out of hospital activity. Pacemakers were optimally programmed and full disclosure 24‐hour Holter ECG recordings were obtained during everyday activities. Close visual analysis of these tracings revealed that rate response is active for < 15% of the 24‐hour study period with high rate response (paced rate above 100 beats/min) for just 5% of the day showing peak activation between 1600 and 2000 hours. Low rate response (paced rate below 100 beats/min but 5 beats above base rate) was maximal between 0800 hours and midday and comprised 10% of all heart beats during the study period. Thirty percent of study patients were nonpacemaker dependent and rate response in these subjects was significantly (P <0.001) Jess active between 0800 hours and midday than in pacemaker dependent patients though it was equivalent at all other times. Nonpacemaker dependent patients achieved natural sinus response in the morning and tended to rely on pacemaker supplied rate response in the latter part of the day.
Real‐Time, Automated, Interactive Cardiac Electrophysiology Testing
Authors: BUCKLES DAVID S. , HAROLD MARK E. , GILLETTE PAUL C. , FYFE DEREK A. , BLAIR HENRY L. , TAYLOR ASHBY B. , WILES HENRY B.
Published: July 2006

We describe a new automated interactive system that performs all of the functions required for complete evaluation of the intracardiac conduction system, for inducing, terminating and analyzing tnchydys‐rhythmias, and for locating and characterizing accessory atrioventricuJar (AV) connections and ectopic foci. In the first year of operation, the system was used to conduct 220 electrophysiology studies. These ranged from simple postoperative evaluation of the conduction system to complete tachycardia studies during pharmacological manipulation of the patient. Patient age at time of catheterization ranged from 6 days to 70 years, with median age of 8 years and 7 months. Advantages accruing from automated electrophysiology testing with this system included great precision and accuracy of timing measurements, flexibility in designing and implementing pacing protocols, and rapid management of induced or spontaneous dysrhythmias. Significant savings of time and labor were achieved by computer generation of reports and graphs as opposed to manual data extraction and plotting. The single most significant advantage is the ability of the system to provide information on a real‐time basis, permitting the electrophysiol‐ogist to analyze, modify, extend or curtail the procedure.