bluuebunny/crossref_metadata_2025 huggingface dataset:
The Chronaxie Time and Its Practical Importance
Authors: IRNICH W.
Published: July 2006

Describing mathematically, the intensity duration curves of electrostimulation by hyperbolas, Lapicque introduced two terms which characterized the functional relationship: “Rheobose” was the lowest intensify with indefinite pulse duration which just stimulated muscles or nerves. “Chronaxie” was that pulse duration at which the threshold intensity was twice that of the rheobase. Up to now, both terms have never played an important role in cardiac pacing.

However, it can be shown that the chronaxie, especially, is an important parameter—influenced by several factors such as electrode size, material, and stimulation mode—which may help match the generator to its electrode. Practical consequences may be derived from the concept of chronaxie:

A pulse duration longer than the chronaxie is not desirable because current consumption is increased without decreasing the threshold significantly.

Pacing with constant current needs twice that pulse duration of constant voltage stimulation.

Smaller electrodes are more favorable because the pulse duration they need may be reduced without losing safety.

Estimation of the safety margin with decreasing output of the generator or with programmable pulse duration is possible if the chronaxie of a specific electrode is known.
Hypersensitive Carotid Sinus Syndrome Manifested as Cough Syncope
Authors: WENGER THOMAS L. , DOHRMANN MARY L. , STRAUSS HAROLD C. , CONLEY MARTIN J. , WECHSLER ANDREW S. , WAGNER GALEN S.
Published: July 2006

We describe a patient with cough syncope who was found to have carotid sinus hypersensitivity with mixed cardioinhibitory and vasodepressor responses. Symptoms were ameliorated by denervation of the more hypersensitive carotid sinus. Spontaneous atypical Wenckebach cycles in this patient were caused by the combined hypersensitive cardioinhibitory and vasodepressor responses. This report stresses the importance of checking blood pressure as well as heart rate in all pa‐tients in whom carotid sinus syndrome is suspected.
Three‐Year Clinical Experience with a New Endocardial Screw‐In Lead with Introduction Protection for Use in the Atrium and Ventricle
Authors: BISPING H.J. , KREUZER J. , BIRKENHEIER H.
Published: July 2006

There is still a high incidence of dislodgement, threshold rises, and loss of sensing with permanent transvenous endocardial leads. Atrial leads are an even greater problem and require particularly reliable methods of fixation. In March, 1976 we reported our preliminary results from animal experiments using a new transvenous screw‐in lead with introduction protection. This lead differs from other screw‐in models as its spiral tip is retracted in the insulating tube during insertion. For fixation purposes a torque is applied to the proximal end of the conductor coil, which is loosely positioned within the tube, and this moves the helical electrode forward. One hundred and fifty endocardial electrodes have been implanted; 127 of them in the dilated ventricle and 23 in the atrium. The technique of introducing the lead into the vein (cephalic or jugular) was the same as that for conventional leads. It was easy to manage and quite uncomplicated. The fixation features in the atrium or the ventricle were sufficiently reliable to allow some patients to go home several hours post‐implant. The total working time of the leads used has been 900 months; the overall complication rate is 2%.
Time Dependence of Unipolar Cathodal and Anodal Strength‐Interval Curves
Authors: MEHRA R. , McMULLEN M. , FURMAN S.
Published: July 2006

Following pacemaker electrode attachment, greater ventricular vulnerability to arrhythmias exists in an acutely is‐chemic ventricle with a univocal anodal than cathodal stimulus falling on the T wave, due to the shorter refractory period exhibited by an anodal stimulus. In order to determine the relationship between anodal and cathodal refractory period at various times following endocardial electrode insertion, ventricular strength‐interval curves were determined in nine dogs. With stable electrode position, serial measurements were made for a mean duration of 44 days. It was observed that during the first five days, the anodal refractory period was significantly shorter than cathodal, but within 15–20 days this relationship was reversed in all dogs. The longer anodal refractory period was observed up to the end of each study. These results suggest that due to shorter anodal refractory period, greater vulnerability to arrhythmias may occur with an anodal than cathodal stimulus in the initial 15–20 days following electrode insertion.
Electrophysiologic Properties of Hydralazine in Man
Authors: GOULD LAWRENCE , REDDY C.V. RAMANA , ZEN B. , SINGH B.K. , BECKER WILLIAM H.
Published: July 2006

There is considerable interest in selecting the proper drug to preserve the ischemic myocardium, or twilight zone, in a patient with a recent myocardial infarction, Vasodilator therapy with an infusion of nitroprusside1 or phentolamine2,3 has been shown to improve left ventricular function by reducing both preload and afterload. Sublingual nitroglycerin4 as well as an infusion of nitroglycerin5 can also alleviate left ventricular failure in patients with an acute myocardial infarction. Similarly, chronic congestive heart failure patients, irrespective of the etiology, improve hemodynam‐ically after an infusion of phentolamine,6,7 nitroprusside8 or hydralazine.9 Oral nitrates,10 phentolamine,11 and hydralazine12 have also been demonstrated to produce improvement in chronic heart failure patients. Recently data has become available on the effects of phentolamine.13 nitroglycerin14 and nitroprusside15 on cardiac conduction in man. However there is no information on the electrophysiological properties of hydralazine in man. The present study involving 12 human subjects was undertaken lo determine what effect iniravenously administered hydralazine has on the human conduction system.
AV Node Dysfunction in the Mitral Valve Prolapse Syndrome
Authors: GREENSPON ARNOLD J. , SCHAAL STEPHEN F.
Published: July 2006

The mitral valve prolapse syndrome is associated with a variety of atrial and ventricular arrhythmias. A portion of these patients manifest bradyarrhythmias, which in turn, may be the cause of lightheadedness and syncope. This study details the clinical and electrophysiologic characteristics of seven patients with symptomatic mitral valve prolapse and AV node dysfunction. The electrophysiology study demonstrated either a prolonged AH interval or abnormal response to atrial pacing in six of seven patients. A significant proportion of these patients had abnormalities of sinus node function and distal His‐Purkinje conduction in addition to AV node dysfunction. AV node dysfunction in symptomatic patients with mitral valve prolapse may be secondary to autonomic dysfunction or diffuse conduction system disease.
Clinical Experience with a Programmable Pacemaker
Authors: MacGREGOR DAVID C. , VENKATARAMAN KALYANASUNDARAM , BILITCH MICHAEL
Published: July 2006

As part of a study to evaluate a new programmable pacemaker, 15 patients received lithium‐powered R‐wave inhibited, unipolar pulse‐generators (CPI* Model 0505). Five were initial implants (Group I) and 10 were pulse generator replacements (Group II). The follow‐up period ranged from 1 to 18 months (mean 11 months). There were 5 deaths unrelated to the pacemaker. Three instances of pacemaker failure were identified and were characterized by a sudden loss of pacemaker output. The malfunction, traced to a 10 kHz timing crystal, has been corrected in subsequently manufactured pulse‐generators. In 11 patients, the pacemakers were programmed at a pulse width which was twice the threshold determined at 3 months. Four were programmed at 0.1 ms, three at 0.2 ms and four at 0.4 ms. Although no complications were seen in patients programmed at 0.1 ms pulse width, it might be advisable to leave pacemakers at 0.2 ms or greater for chronic pacing in patients with a pulse width threshold at 0.05 ms.
Transvenous Magnetic Tip Lead System for Permanent Pacing of the Heart. A Preliminary Report
Authors: HOLEN OTTO , REENSTIERNA E.G. BERTIL
Published: July 2006

A preliminary report. An electrode for transvenous permanent ventricular pacing equipped with a supermagnet was implanted in six dogs in the apex of the right ventricle for severel weeks. As no signs of myocardial perforation occurred, the device which consists of the magnetic tip lead and an external supermagnet applied to the precordial region of the chest wall was implanted in 14 patients. The lead was introduced through the right cephalic vein in 12 patients and through the right external jugular vein in the remaining 2 patients. Threshold values were measured twice a day in 12 patients who received a Siemens‐Elema Vario pacemaker 629. The average peak threshold was reached on the 11th day after implantation. No pacing failure or other signs of acute dislodgement of leads occurred during the first 30 days.
The Effect of Procainamide on Delayed Activation Potentials in a Patient with Ventricular Tachycardia
Authors: BAILEY BRIAN , TAN ARTHUR
Published: July 2006

In a patient with ventricular tachycardia and previous myocardial infarction, delayed activation potentials were recorded from a region of the posterolateral wall of the left ventricle at electrophysio‐logical study. Procainamide, administered intravenously, initially caused increased delay and later, in higher dosage, second‐degree block of the delayed potentials.
An Unusual Complication of the Unremoved Unwanted Pacing Wire
Authors: DALAL J.J. , ROBINSON C.J. , HENDERSON A.H.
Published: July 2006

A ease of external jugular vein thrombosis is described. This occurred following failure to remove on unwanted pacing wire by sustained traction and its subsequent migration from the subclavian vein into the external jugular vein.
Atrial and Ventricular Vulnerability in a Patient with the Wolff‐Parkinson‐White Syndrome
Authors: PETERS ROBERT W. , GONZALEZ ROLANDO , SCHEINMAN MELVIN M.
Published: July 2006

An electrophysiologic study was carried out in a patient with the Wolff‐Parkinson‐White syndrome and a history of spontaneous atrial fibrillation but with no evidence of organic cardiac disease. A single induced premature ventricular depolarization resulted in ventricular tachycardia followed by ventricular fibrillation. Similarly, atrial pacing or premature atrial stimulation resulted in frequent episodes of atrial fibrillation or flutter, The atrial and ventricular effective refractory periods were 180 ms and < 160 ms, respectively, at a driven cycle length of 480 ms. Intravenous administration of procainamide resulted in lengthening of the refractory periods and failure to induce either atriaJ or ventricular arrhythmias with pacing. In most patients with enhanced atrioventricular nodal or accessory atrioventricular nodal bypass, the mechanism of ventricular tachycardia is related to an inordinately rapid ventricular response during supraventricular arrhythmias. In our patient, a unique mechanism was apparent: atrial and ventricular vulnerability to fibrillation was associated with extremely short myocardial effective refractory periods. The relationship of this finding to sudden cardiac death bears further study.
Venous Obstruction in Permanent Pacemaker Patients: An Isotopic Study
Authors: PAULETTI MARINA , DI RICCO GIORGIO , ANO SOLFANELLI STEP , MARINI CARLO , CONTINI CARLO , GIUNTINI CARLO
Published: July 2006

Isotope venography was used to study the venous circulation proximal to the superior vena cava in two groups of pacemaker patients, one with a single endo‐cavitary electrode and the other with multiple pacing catheters. A control group of patients without pacemakers was also studied. Numerous abnormalities were found, especially in the group with multiple electrodes. These findings suggest that venous obstruction is a common complication of endocardial pacing.
Chronic Ventricular Pacing with Ventriculoatrial Conduction Versus Atrial Pacing in Three Patients with Symptomatic Sinus Bradycardia
Authors: EL GAMAL M.I.H. , VAN GELDER L.M.
Published: July 2006

Three patients with symptomatic sinus bradycardia due to sick sinus syndrome were treated with permanent ventricular pacing for periods rang‐ing from 2.5 to 4 years. All three patients had ventriculo‐atrial conduction on routine electrocardiography. Although ventricular pacing was effective, they complained of fatigue, lightheadedness, and near syncope. Hemodynamic studies revealed the presence of regular cannon waves in the right atrium as well as in the pulmonary artery wedge pressure curves. Temporary atrial pacing resulted in disappearance of the cannon waves and a significant rise in cardiac output (32–48%). After narmal atrio‐ventricular conduction was confirmed by rapid atrial stimulation and His bun‐dle electrocardiography, the pacing mode was changed to permanent atrial pacing on demand. The effort tolerance of the patients marked by improved, and the previ‐ously mentioned symptoms disappeared. Control hemodynamic studies 9 to 12 months affer impiantation of the atrial demand pacemaker showed that the im‐provement in cardiac performance was maintained.
Autointerference of Demand Pulse Generators
Authors: BAROLD S. SERGE , LEVINE PAUL A.
Published: July 2006

We describe in this report two cases of autointerference of demand pacemakers by signals originating within a pulse generator itself rather than the electrode or connection. Restoration of regular fixed rate pacing upon application of the magnet cannot differentiate between an external or internal source of oversensing as exemplified in our two cases. The absence of any visible interference on the surface electrocardiogram and the relatively late appearance of autointerference in the life of a pulse generator may mimic an intermittent fracture for insulation defect) with oversensing of false signals. Autointerference of demand pacemakers, although rare, should be added to the list of causes producing oversensing and prolongation of the spike‐to‐spike interval.
Catheter Induced Distal Intra‐Hisian Right Bundle Branch Block in a Patient with Persistent Proximal Intra‐Hisian Complete A‐V Block
Authors: SANTARELLI PIETRO , BELLOCCI FULVIO , LOPERFIDO FRANCESCO , ANSALONE GERARDO , COPPOLA ELDA , ZECCHI PAOLO
Published: July 2006

We describe a patient with complete intra‐Hisian A‐V block and narrow QRS who developed catheter‐induced right bundle branch block during an electrophysiological study. Selective His bundle pacing was performed during complete intra‐Hisian A‐V block and right bundle branch block pattern; the distal His bundle pacing nor‐malized the QRS complex, while a more proximal His bundle stimulation showed a right bundle branch block configuration with the persistence of the proximal intra‐Hisian lesion responsible for the complete A‐V block. These electrophysiological findings suggest that the catheter‐induced right bundle branch block in our patient was due to a focal lesion in the distal part of the main His bundle, To our knowledge, this is the first report of documented multilevel lesions within the His bundle in man.
Dual Mode Sensing by a Variable Cycle Ventricular Synchronous Pulse Generator
Authors: Barold S. Serge , EDWARDS LYNN M. , HAUSER ROBERT G.
Published: July 2006

When the Intermedics Cyberlith pulse generator is operating in its R‐wave synchronous (VVT) mode, sensed events may trigger stimulus pulses or inhibit the output circuit. This dual mode response to sensed signals is the result of a variable timing cycle which includes an inhibit alert period (IAP) as well as a synchronous alert period (SAP). Sensed events occurring during the IAP result in inhibition of stimulus pulse output and resetting of the timing circuit. Consequently, during a continuous ECG rhythm strip one may observe synchronous and inhibited sensing responses and slowing of the pacing rate below the programmed rate of the pulse generator.
Mechanisms of Spontaneous Tachycardia Termination in a Patient with the Wolff‐Parkinson‐White Syndrome and Dual Atrioventricular Nodal Pathways
Authors: ADAMS JAMES R. , HESS DAVID , SCHEINMAN MELVIN M.
Published: July 2006

A patient with the Wolff‐Parkinson‐White syndrome and recurrent bouts of paroxysmal supraventricular tachycardia underwent electrophysiologic studies. These studies revealed evidence of dual atrioventricular nodal pathways and a septal accessory pathway. The tachycardia circuit involved anterograde conduction over a slow atrioventricular nodal pathway and retrograde conduction over the accessory pathway. Spontaneous tachycardia termination was frequently observed, was almost always abrupt, and was associated with a beat‐to‐beat decrease in the A‐H interval, In this patient, the mechanism for spontaneous tachycardia termination appeared to be an abrupt shift in anterograde conduction from the slow to the fast pathway, advancing the tachycardia so that the block occurred in the accessory pathway (or atrium). To our knowledge, this mechanism of spontaneous tachycardia termination has not been described previously. Use of agents to facilitate fast atrioventricular nodal conduction (i.e., atro‐pine) may be effective in tachycardia termination for these patients.
Screening of Solid and Porous Materials for Pacemaker Electrodes
Authors: HIRSHORN MICHAEL S. , HOLLEY LORAINE K. , HALES J. ROBERT S. , MONEY DAVID K. , YOUNG FRANK A. , SPECTOR MYRON , WICKHAM GEOFFREY G.
Published: July 2006

Several different materials, including one which was porous, were studied to assess their properties as pacemaker electrode tips. Leads were implanted in sheep for periods up to one year. Electrical measurements were made during the implant period and histopathological examination performed after sacrifice. Although titanium vapor‐deposited carbon, and silver did not lower the chronic stimulation threshold below that of platinum, their electrical characteristics were within generally acceptable limits. Zinc evoked a severe tissue reaction and a high threshold. Porous titanium alloy electrodes demonstrated reduced dislodgement, more frequent attachment and a lower sensing impedance than other electrodes.
After‐Potential Oversensing by a Programmable Puise Generator
Authors: HAUSER ROBERT G. , SUSMANO ARMANDO
Published: July 2006

Oversensing and recycling due to pacemaker stimulus after‐potentials are recognized complications of non‐competitive pacing. Often mas‐querading as T‐wave sensing, after‐potential oversensing may result in slowing or acceleration of pacing rate. We report two cases of after‐potential oversensing in po‐tients with R‐wave inhibited (VVI) programmable pulse generators. In both coses, recycling of the pulse generators by the sensed after‐potentials resuited in slowing of the pacing rates. This phenomenon was abolished non‐invasively by decreasing the duration or width of the stimulus pulse which diminished the magnitude of the after‐potential signal.
Atrial Systole and Ineffective Pacemaker Stimuli
Authors: DE ORO ANTONIO GOICOLEA , AYALA GERMÁN SERRANO , AYZA MIGUEL WILHELMI , MEABE JUAN ANTONIO ZUAZO , DÍEZ JOSÉ RAMÓN GUTIÉRREZ , GARRIDO RAMÓN HERNÁNDEZ , RIPOLL ANTONIO SARABIA , ALVAREZ JUSTO GONZÁLEZ
Published: July 2006

An unusual case of pacemaker failure induced by atrial activity is presented. The pacemaker stimulus was ineffective for ventricular capture not only with low energy output (decreased pulse duration) of the generator, but also with pulse width two to three times the stimulation threshold. The two possible mechanisms of this phenomenon, one electrotonic and the other mechanical, are discussed. This report strongly supports the mechanical hypothesis. (PACE, Vol. 4, September‐October, 1981)
The Treatment of Ventricular Tachycardia Using an Automatic Tachycardia Terminating Pacemaker
Authors: GRIFFIN JERRY C. , MASON JAY W. , ROSS DAVID L. , CALFEE RICHARD V.
Published: July 2006

Implanted cardiac pacemakers may be used in the management of selected patients with ventricular tachycardia unresponsive to other forms of medical and surgicaJ therapy. We would like to report the successful treatment of such a patient utilizing a new multiprogrammable automatically activating ventricular burst pacemaker. Thorough electrophysiologic study preceded implantation, and was instrumental in choosing an effective terminating technique, in identifying the need for adjunctive drug therapy, and in testing the safety and efficacy of the implanted system. (PACE, Vol. 4, September‐October, 1981)
Overdrive and Programmed Atrial Electrostimulation in the Study of the Electrogenetic Mechanism of Atrial Flutter in Man
Authors: DISERTORI MARCELLO , MOLINIS GIOVANNI , INAMA GIUSEPPE , VERGARA GIUSEPPE , DEL FAVERO ANGELO , FURLANELLO FRANCESCO
Published: July 2006

The response of atrial flutter (AF) to programmed atrial stimulation (PAS) (13 cases) and overdrive atrial padng (OAP) was studied in a total of 13 patients. During PAS the return cycle was equal to the basic cycle of AF in six patients, shorter in one patient, and slightly longer in six; it was never compensatory, Atrial flutter terminated in two patients by PAS and by OAP in three. In 4 patients, PAS resulted in an acceleration of the AF rate, followed by spontaneous interruption within 2 seconds. In the remaining patients, the stimulation either converted the AF into an uncommon type of AF (two patients) or into atrial fibrillation that was followed by spontaneous return to sinus rhythm, in two patients it was possible to reproduce the AF with PAS; in one of the patients another type of AF was induced. Some of the data observed suggest a reentry circuit as the electrogenetic mechanism responsible for AF in man.
Unipolar Sensing Abnormalities: Incidence and Clinical Significance of Skeletal Muscle Interference and Under sensing in 228 Patients
Authors: SECEMSKY SOLOMON I. , HAUSER ROBERT G. , DENES PABLO , EDWARDS LYNN M.
Published: July 2006

Compared to bipolar Jead configurations, unipolar pacing systems presumably enhance sensing of cardiac electrical events but are more susceptible to electrical interference, including skeletal myopotentials The incidence and clinical significance cf oversensing and of undersensing by unipolar R‐wave inhibited pacemakers in 228 patients were assessed by 24‐hour Holter monitoring and/or by pectoral muscle exercises. Overall, 38% of patients exhibited oversensing and false inhibition due to skeletal myopotentials Symptoms due to oversensing occurred in 14% of patients and 58% of these required corrective intervention The presence of silastic coating on the pulse generator had no effect on the sensing of myopotentials In addition, the incidence of undersensing as assessed by Hoiter monitoring was 17% despite adequate implantation R wave amplitudes Thus, oversensing remains a major clinical problem when using unipolar pacemaker systems and their use has not eliminaled undersensing
Pacemaker Inhibition by Myopotentials Detected by Holter Monitoring
Authors: JACOBS LAWRENCE J. , KERZNER JAY S. , DIAMOND MORTON A. , BERLIN HOWARD F. , SPRUNG CHARLES L.
Published: July 2006

Ambulatory eiectrocardiography revealed myopoiential inhibition of a demand ventricular pacemaker in each of two patients. Although it was first regarded as artifact, fine baseline osciliations observed during apparent pacemaker malfunction actualiy signalled skeletal muscie‐induced pacemaker inhibition. Though not widely recognized, myopotential inhibition may be a common occurrence in unipolar lead systems. As greater numbers of patients undergo ambulatory monitoring, awareness of this phenomenon should become more widespread
Frequency and Variability of Ventricular Premature Contractions—The Influence of Heart Rate and Circadian Rhythms
Authors: STEINBACH K. , GLOGAR D. , WEBER H. , JOSKOWICZ G. , KAINDL F.
Published: July 2006

Present knowledge about arrhythmias is still too limited to prevent sudden cardiac death Long‐term ambulatory ECG monitoring should be the method of choice in further investigating and evaluating the possible relationships between the frequency of arrhythmias and heart rate (MR), circadian patterns, and effects of drugs Using a computer‐supported, semiautomatic anaiysis system, 77 patients with a mean premature ventricuiar contraction (PVC)‐rate of over 1% were monitored for 24 hours (group A). Ten other patients with PVC's of over 1% were monitored for up to 96 hrs each, continuousiy, to demonstrate the reproducibility of possible circadian PVC's and HR patterns (group B) Another group of 44 patients (group C) underwent long‐term ECG monitoring of 24 hrs before and during drug therapy with disopyramide (n = 15 pts, 200 mg tid), mexiletine (n = 13 pts, 200 mg t.i.d.), acebutoiol (n = 9 pts, 200 mg bid) and propafenon (n = 7 pts, 300 mg t i.d.) to judge the drug effects in relation to their specific chronotropic properties. In group A patients there was a significant correlation (r = ‐0 602) between mean PVC frequency and respective PVC variabilities The latter increase with a reduction of the PVC rate and vice versa A circadian pattern of HR and PVC's can be demonstrated in the majority of group A and B patients. By using Scheffe's test to determine the required PVC reduction, the statistical PVC reduction curve (p < 0 05) does not conform to the PVC‐aboiition curve (PVC beiow 1%) in group B patients If patients without circadian PVC/HR patterns are under antiarrhythmic therapy, they need a much higher mean PVC‐reduotion rate to reach the statistical significance level than patients without such a PVC and HR behavior. Drugs administered in Group C patients had different chronotropic effects Heart rate spectra were demonstrated for each antiarrhythmic drug used The distribution of arrhythmias, their variability, HR, circadian rhythm and the activity of antiarrhythmic drugs should be taken into account to narrow the gap between current antiarrhythmic treatment and the prevention of sudden cardiac death
An Analysis of 114 Consecutive Patients with Complete One‐Year Follow‐Up
Authors: BASHORE THOMAS M. , BURKS JOHN M. , WAGNER GALEN S.
Published: July 2006

This study assesses the clinical and electrode complications associated with the use of the epicardial screw‐on electrode technique for permanent ventricular pacing. The records of 114 consecutive patients who received screw‐on epicardial electrodes were analyzed in‐hospital and at one year following implantation We compared two techniques of implanting the screw‐on electrode: 72 transmediastinal (TM) and 42 subxiphoid (SX) procedures. Baseline clinical inequalities were not apparent between the SX and TM patients. There was one operative death in the SX series and none among the TM patients. Total hospital mortality was 4% in the SX group and 2% in the TM group. In‐hospital morbidity in the SX series (13/72—18%) was less than the TM group (14/42—33%), largely due to pleural entry and necessity for more frequent chest tube placement in TM patients. Electrode complications were low in both groups (3% in‐hospital and 3% late; total 6/114, or 5%). Morbidity and mortality of these approaches to direct myocardial pacing remain noticeably higher than reported results of some transvenous series. Excellent electrode stability can be attained using the screw‐on electrode, however, and the SX approach offers lower hospital morbidity than the TM method
Coexistence of Tachycardia Dependent (Phase 3) Left Bundle Branch Block and Wolff‐Parkinson‐White Conduction
Authors: Barold S. Serge , WAXMAN MENASHE B. , And ROBERT W. WALD. , CAMERON DOUGLAS A.
Published: July 2006

A 53‐year‐old woman is described with tachycardia dependent block (Phase 3 block) within the left bundie branch and a right‐sided accessory AV bypass tract Simple bedside autonomic maneuvers allowed an accurate assessment of these com‐plex conduction disturbances
Radiation Effects on Implanted Pacemakers
Authors: Furman Seymour
Published: July 2006

Readers of PACE will recognize a change beginning with this issue. PACE has rapidly become a major force in the fields of pacing and electrophysiology and has, for the last two years, published more articles in the medicine and technology of cardiac pacing than any other English language journal. The submissions have heen of very high quality and the pressure for publication has been correspondingly great. Beginning in January 1982 each issue has been increased in size from 128 to 144 pages. The Editor and Publishers recognized rapidly that the increase was inadequate to service those who had submitted manuscripts of quality. Therefore, with the March 1982 issue, the number of text pages will increase again by 16 to a total of 160 per issue. Some change in type format will further increase the amount of material which can be published without reducing readability. Finally, a lighter paper, which is of identical quality to the major American cardiology journals, will allow mail distribution without prohibitive postage costs. All of these changes have been accommodated within the existing subscription rates. We hope that all of the changes will enhance the value of PACE to our readership and to the authors who submit their work.
Natural History of Severe Sinus Bradycardia Discovered by 24 Hour Holter Monitoring
Authors: LICHSTEIN EDGAR , AITHAL HARTHATTU , JONAS STERLING , GREENGART ALVIN , SANDERS MIGHAEL , HOLLANDER GERALD , WEISFOGEL GERALD
Published: July 2006

This study follows patients with severe sinus bradycardia (40 beats per minute for 6 seconds or greater) in order to evaluate mortality and the effectiveness of permanent pacemaker insertion. Severe sinus bradycardia was noted on a 24‐hour Holter in 95 patients. There were 64 males and 31 females with a mean age of 69 ± 10 years. All were availahle for follow‐up at 26 ± 13 months. Twenty‐eight required a permanent pacemaker at an average of 2 ± 3 months after the Holter. Of this group 12 had the Holier for arrhythmia, 11 for cerebral symptoms, 4 for palpitations and 1 for chest pain. Only 1 was taking digitalis and no patients were taking Inderal. Six (21%) died at a mean interval of 21 ± 15 months following pacemaker insertion. Sixty‐seven did not require pacemaker insertion. The indications for Holter monitoring were arrhythmia in 16, palpitations in 19, cerebral symptoms in 20 and chest pain in 12. Four of these patients were on digitalis, 8 on Inderal, and 4 on both. Eleven (16%) died at a mean interval of 12 ± 7 months after the initial Holter recording. Dizziness and/or syncope reoccurred in 22. Five had these symptoms even after pacemaker insertion. We conclude that severe sinus bradycardia is associated with a significant mortality. Insertion of a permanent pacemaker may decrease recurrent symptoms ahd slightly increase time of survival, but does not appear to influence the overall survival rate. (PACE, Vol. 5, March‐April, 1982)
Two Leads in One Introducer Technique For A‐V Sequential Implantations
Authors: BOGNOLO DIEGO A. , VIJAYANAGAR R. , ECKSTEIN PAUL F. , JANSS BRAD
Published: July 2006

Thirty‐six (36) consecutive patients underwent implantation of transvenous atrioventricular sequential pacing systems by inserting the atrial and ventricular leads together through one #14 French sub‐clavian introducer. This technique has been easy, reliable and free of complications. (PACE, Vol. 5, March‐April, 1982)
Pacer‐Induced Tachycardia Associated with an Atrial Synchronous Ventricular Inhibited (ASVIP) Pulse Generator
Authors: Serge Barold S. , TOLENTINO ALFONSO O. , JAVIER ROGER P. , BYRD CHARLES , SAMET PHILIP
Published: July 2006

A 68‐year‐old white male underwent permanent pacemaker implantation with an atrial synchronous ventricular inhibited pulse generator (Medtronic model 2409) because of syncope and abnormal H‐V interval of 70 ms. Paroxysmal bouts of pacemaker associated tachycardia were subsequently recorded on several occasions, initiated and terminated by spontaneous ventricular premature beats. The mechanism for the occurrence of the tachyarrhythmia is discussed in detail and the functional characteristics of the pulse generator are described. Replacement of the unit with a different pacer device prevented further occurrence of the arrhythmia. (PACE, Vol. 5, March‐April, 1982)
Refractory Supraventricular Reentry Tachycardia Treated by Radiofrequency Atriai Pacemaker
Authors: SOLTI FRANCIS , SZABÓ ZOLTÁN , CZAKÓ ELMER , BODOR ALEX , RÉNYIVÁMOS FRANCIS
Published: July 2006

The authors report on a case of drug‐resistant supraventricular tachycardia with frequent and long‐lasting paroxysmal attacks. Electrophysiologic study revealed that the supraventricular tachycardia was based on a reentry circuit. The attack was regularly induced by premature delay 340‐400 ms atrial stimulation and il could aiways be terminated by rapid atrial stimulation within 1‐2 seconds. Atrioventricular 2:1 hlock occurred with very rapid atrial stimulation of > 190/min. The patient received a radiofrequency atrial pacemaker, and at the first sign of a tachyarrliythmia he switched on the instrument for 1–2 sec. and the attack was promptly terminated, (PACE, Vol. 5, March‐April, 1982)
Pulse Width Dependent Increase in the Pacemaker Automatic Interval
Authors: OHM OLE‐JÖRGEN , BREIVIK KJELL , HAMMER ERLING
Published: July 2006

From a total of 51 patients equipped with rate and pulse width adjustable pulse gen erators (Microlith‐P 0505, Microthin‐PI 0522) implanted over the last 3 years, 10 (19.6%) showed an un expected drop in pacemaker pulse rate during pulse width programming. For one of the pulse gen erators used (Microthin‐PI 0522), unexpected rate decrease occurred in 7/13 cases (53.8%). For all ex cept one patient, decrease in pacemaker pulse rate corresponded with the total refractory period of the pulse generator (320 ms), at a certain pulse width when rate drop first occurred. In seven of the patients the pulse generator automatic interval was extended from 13 ms to 171 ms beyond the re fractory period. In two patients it was necessary to replace the pulse generators. Our study strongly proves that this abnormal pacemaker functioning is a result of sensing of the polarization voltage at the pacemaker electrode/tissue interface and/or the T‐wave. The polarization voltage is highly dependent on the total pacemaker electrode/tissue interface impedance. Using typical values for pulse genera tor output and input resistance and output capacitance, Faraday resistance, Helmholtz capacitance and tissue resistance at the electrode/tissue interface it was shown mathematically that in some cases the polarization voltage alone would be of sufficient amplitude and slew rate for pacemaker inhibi tion. The study demonstrates an urgent need for change in the filter characteristics by making the pulse generators less sensitive in the low frequency region and reducing the polarization voltage by reducing the output circuit capacitance. (PACE, Vol. 5, May‐June, 1982)
Sulfinpyrazone: An Antiarrhythmic Drug?
Authors: ROOS JULIUS C. , DUNNING AREND J.
Published: July 2006

The patients were studied by intracardiac electrocardiography and programmed stimulation before and after an intravenous bolus injec tion of either 500 mg sulfinpyrazone or a placebo. We found no consistent clinical or statistical effects of sulfinpyrazone on sinus rate, sinus node recovery time, sinoatrial conduction time, conduction intervals during spontaneous cardiac activity and atrial pacing, Wenckebach point and refractory periods of the atrium, AV node, His Purkinje system and right ventricle. We conclude that sulfinpyra zone has no clinican electrophysiological effects comparable with those of known antiarrhythmic agents and that a direct antiarrhythmic action is an unlikely explanation for the reduction of sudden death in postinfarction patients treated with this drug. Antiarrhythmic activity by an indirect mecha nism, related to the antipaltelet properties of the drug, or by metabolites of sulfinpyrazone, remains a possibility requiring further investigation. PACE, VoJ. 5, May‐June, 1982)
The Ventricular Paced QT Interval—The Effects of Rate and Exercise
Authors: MILNE J.R. , WARD D.E. , SPURRELL R.A.J. , CAMM A.J.
Published: July 2006

Changes in the QT and QTc intervals in 19 patients were studied at a ventricular paced rate difference of 50 beats/min. In all patients the measured QT interval shortened as the pacing rate was increased, from a mean value of 441 ms to 380 ms (p < 0.001), but when correct ed for heart rate the QTc‐ lengthened from a mean value of 518 ms to 575 ms. In 11 patients the QT in terval was measured at rest and immediately following exercise sufficient to increase the atrial rate by approximately 50 beats/min at identical ventricular paced rates. In all patients exercise‐induced QT interval shortening from a mean value of 433 ms to 399 ms (p < 0.001). These results show first that Bazett's formula is unsuitable for correction of QT interval changes induced by ventricular pacing, and second that heart rate and changes in sympathetic tone independently influence the duration of the QT interval. It is suggested that these resuits are relevant to the design of physiological pacemakers in which the duration of the QT interval influences the discharge frequency of the pacemaker and to the consideration of ventricular pacing for the treatment of abnormal repolarization syndromes. (PACE, Vol. 5, May‐June, 1982)
Symptomatic Bradyarrhythmias in the Adult: Natural History Following Ventricular Pacemaker Implantation
Authors: SIMON ARTHUR B. , JANZ NANCY
Published: July 2006

The preimplantation arrhythmias, coexistent medical conditions, the causes of death, and survival course are described for 399 patients who received their initial ventricular pacemaker implantation for a bradyarrhythmia (AV block, sinus node disease, and hypersensitive carotid sinus syndrome) at the University of Michigan from 1961 to 1979. Factors which correlated with a poor survival are elucidated. Survival for those with sinus node disease was virtually identical to those with AV block, with only 63% surviving over five years. Advanced age and congestive heart failure prior to implantation, and underlying ischemic or hypertensive heart disease portended a poorer survival in both groups. Patients with hypersensitive carotid sinus syndrome had a distinctly better prognosis—no deaths occurred until the eighth year after pacing. Patients with no underlying heart disease and those with valvular disease did remarkably better than those with an ischemic or myopathic etiology. Apparent progression or complications of the underlying heart disease was the major cause of mortality. Sudden death, congestive heart failure, myocardial infarction, and major arrhythmias were the causes of death in 48% of those who died. Implications of improved pacing modalities an late complications and death are discussed. (PACE, Vol. 5, May‐June, 1982)
Termination of Ventricular Tachycardia by Programmed Extrastimuli from an Externally‐Activated Permanent Pacemaker
Authors: LEON GREENE H. , GROSS BRIAN W. , PRESTON THOMAS A. , WERNER JEFEREY A. , KIME GENA M. , HESSEL EUGENE A. , WEAVER W. DOUGLAS , DUNCAN JAMES L.
Published: July 2006

Two patients with hemodynamically well‐tolerated recurrent ventricular tachycardia, drug resistani and previousiy requiring numerous external electrical cardioversions, had a permanent pacemaker implanted which could be programmed lo deliver extrastimuli to convert the ventricular tachycardia to normal sinus rhythm. The patient‐ or physician‐activated device can be programmed to induce or terminate ventricular tachycardia with extrastimuli delivered at the predetermined intervals which consistently induced or terminated the arrhythmia in the electrophysiology laboratory, allowing repeated evaluation of drug regimens. The pacemaker has reliably, painlessly, and consistently induced and terminated repeated episodes of ventricular tachycardia. This programmable pacemaker offers an alternative therapy for patients with hemodynamically weil‐tolerated refractory ventricular tachycardia. (PACE. Vol. 5, May‐June, 1982)
Accelerated Junctional Tachycardia at a Rate of 190 Beats/Minute Following Cryosurgery and Aneurysmectomy for Ventricular Tachycardia: A Case Report
Authors: KERR CHARLES R. , GALLAGHER JOHN J. , COX JAMES L. , SMITH WARREN M. , STERBA RICHARD
Published: July 2006

In this case study we report a 59‐year‐old man who underwent combined aneurysectomy, endocardial resection, and cryosurgery for recurrent ventricular tachycardia. Following surgery he developed an accelerated junclional tachycardia with rates up to 190/min arising near the area of cryoablation which involved the junctional region. Using intracavitary recording and stimulation this tachycardia was shown to arise from ihe junctional area and had characteristics suggesting accelerated automaticity. During the electrophysiological study the focus of the tachycardia was temporarily obtunded by catheter trauma. After reappearance of the arrhythmia, successful suppression was achieved using diphenylhydantoin. (PACE, Vol. 5, May‐June, 1982)
Tachycardias Related to Atrial Synchronous Ventricular Pacing
Authors: BATHEN JØRN , GUNDERSEN TORSTEIN , FORFANG KØLBJORN
Published: July 2006

Tachycardias related to atrial synchronous ventricular pacing are discussed. Three patients with an implanted Medtronic 2409 VDD pacemaker where tachycardias were initiated by various mechanisms are described. The problems are discussed with relation to patient evaluation and pacemaker technology. (PACE, Vol. 5, Juiy‐August, 1982)
Recurrent Laryngeal Nerve Paralysis Following Pacemaker Introduction
Authors: COPPERMAN YITSCHAK J. , BEISER MICHAEL , SAMUEL YORAM , LANIADO SHLOMO , SHANON ELIAHU
Published: July 2006

Electrode insertion to the heart via subclavian vein puncture has become a commonplace procedure. A case is presented in which employment of this route led to permanent paralysis of the recurrent laryngeal nerve. (PACE, Vol. 5, July‐August, 1982)
Method for Re‐introduction of Permanent Endocardial Pacing Electrode
Authors: BOGNOLO DIEGO A. , VIJAYANAGAR R. , EGKSTEIN PAUL F. , JANSS BRAD
Published: July 2006

This report describes a method for re‐introduction of permanent endocardial electrodes utilizing a standard suhclavian introducer in a patient with limited vascular entry. (PACE, Vol. 5, July‐August, 1982)
Asynchronous Ventricular Pacing: A Rare Cause of Ventricular Tachycardia
Authors: TOMMASO CARL , BELIC NENAD , BRANDFONBRENER MARTIN
Published: July 2006

Asynchronous cardiac pacing may induce ventricuiar tachycardia and fibrillation, particularly in patients with ischemic heart disease and possibly other types of myocardial abnormalities. All patients with implanted asynchronous pacemakers, and those whose demand pacemakers operate in asynchronous mode for any reason, are to he considered at risk from this complication. In patients with serious myocardial abnormalities consistent demand pacing should be assured, even if it requires early pacemaker replacement. Anti‐arrhythmic agents may prove useful for temporary suppression of pacemaker‐induced arrhythmias. (PACE, Vol. 5, July‐August, 1982)
Induction of Ventricular Tachycardia by Pacemaker Programming
Authors: Barold S. Serge , SCHEIBELHOFER W. , GLOGAR D. , PROBST P. , And J. MLGZOCH. , KAINDL F.
Published: July 2006

The induction of ventricular tachycardia or ventricular fibrillation by competitive pacing, especially in the setting of acute myocardial ischemia, is well known. A case of ventricular tachycardia induced by a multiprogrammable unipolar cathodal ventricular pacemaker is reported. The arrhythmia was caused by reprogramming, which necessitates a short switch to fixed rate pacing in this model (Spectrax 5985 SX). This potential hazard is not well established in patients with unipolar pacemakers. The use of the magnet as one of the preconditions for reprogramming should be avoided in future pacemakers. (PACE, Vol. 5, July‐August 1982)
Hemodynamic Effects of Atrial Synchronization in Acute and Long‐Term Ventricular Pacing
Authors: KAPPENBERGER LUKAS , GLOOR HANS O. , BABOTAI ISTVAN , STEINBRUNN WALTER , TURINA MARKO
Published: July 2006

The acute and long‐term hemodynamic benefit from atrial synchronization in ventricular (VAT) pacing has been investigated at rest and during exercise in 10 patients undergoing pacemaker implantation for complete A‐V block. The results were compared to conventional (VOO) ventricular stimulation at rates of 70 BPM and 96 BPM. Cardiac index (CI) in VAT‐pacing increased at rest by 8% and during exercise by 15% more than with VOO pacing (p < 0.01). No significant change between the two different rates of asynchronous pacing was observed. CI at rest and during exercise was unchanged after 10 weeks of VAT‐pacing. CI is regulated by change of stroke volume in VOO‐pacing and by heart rate only with VAT‐pacing. In contrast to earlier results with asynchronous ventricular pacing, the hemodynamic benefit of pacing in an atrial synchronized mode is long‐lasting. Physiologic mechanisms regulate hemodynamics during exercise and in heart failure. (PACE, Vol. 5, September‐October, 1982)
Pacing Threshold Interval with Decreasing and Increasing Output
Authors: SYLVÉN J. CHRISTER H. , HELLERSTEDT MARGARETA , LEVANDER‐LINDGREN MAJ
Published: July 2006

The study was made in 44 patients, of which 23 received a new endocardial electrode and 21 were investigated during pulse‐generator replacement. Indicafion for pacemaker therapy was sino‐atrial bradycardia in 12 patients and atrio‐ventricular block in 32 patients. When the pacing threshold was determined with decreasing output it was found to be 0.6V/0.7mA for new implantations and 2.0 V/2.0 mA with pulse generator replacement. When determined With increasing output the threshold was found to he an average 0.20 V/0.20 mA higher than when determined with decreasing output (threshold interval). The maximal difference observed was 0.70 V/0.55 mA. This threshold interval was of the same size irrespective of pacemaker indication and spontaneous activity and whether the electrode was newly implanted or not. Pacemaker ventricular block of Mobitz type I with Wenckebach periodicity was never observed. (PACE, Vol. 5, September‐October, 1982)
Acute and Chronic Pulse‐Width Thresholds in Solid Versus Porous Tip Electrodes
Authors: BREIVIK KJELL , OHM OLE‐JØRGEN , ENGEDAL HOGNE
Published: July 2006

Sixty‐one patients given programmable pacemakers at initial implantation have been followed for a mean of 18 months (3‐42) wilh non‐invasive measurements of myocardial pulse‐width threshold. Fifty of the patients had CPI 0505/0522 (Microlith‐P/Microthin‐PI) pacemakers with either Cordis 322–462 8 mm ball tip (n = 12), Cordis 322–620 17.5 mm2 (n = 23), or CPI 4116 porous tip electrodes (stimulation area 7.5 mm2 and sensing area 50 mm2) (n = 15). Eleven patients had Medtronic 5985 (Spectrax‐SX) pacemakers with either Medtronic 6907‐R 8 mm2 ring tip (n = 7), 6907 11 mm2 (n = 3) or 6917 myocardial electrodes (area 12 mm2) (n = 1). At acute impant, the ball tip and porous tip electrodes had the lowest stimuialion thresholds, but the differences were only statistically significant in comparison with the 17.5 mm2 electrode (p < 0.01). Chronically there were no significant differences between the various electrodes (p > 0.1), but the ball tip electrode tended to give best long‐term results, and the porous tip electrode the poorest. Thirty‐eight of the 61 patients (62.3%) had chronic pulse‐width thresholds of 0.1 ms or less at ∼5 V output, indicating that pulse‐width programming is a useful way to conserve battery energy. However, at some stage of the study, six of the patients (9.8%) had a pulse‐width threshold of 0.5 ms or more. Pulse width should therefore not be set too narrow in standard nonprogrammable pacemakers. (PACE, Vol. 5, Septemher‐October, 1982)