bluuebunny/crossref_metadata_2025 huggingface dataset:
The Use of Balloon‐Tipped Electrodes for Permanent Cardiac Pacing
Authors: SLOMAN J. GRAEME , MONO HARRY G. , BAILEY BRIAN , COLE ANNETTE , DUFFIELD ANNE
Published: July 2006

A new balloon‐tipped ventricular endocardial electrode for permanent artificial cardiac pacing is described. Following transvenous insertion of [he electrode to the right ventricular apex, the distal balloon is inflated with contrast material in order to wedge the electrode tip between or beneath trabeculae and prevent displacement. Fifty‐nine electrodes were implanted, including a second generation type incorporating a wedge tip as well as the balloon. The incidence of displacement was 17% with 10% of coses being early, and 7% late. Early in (he series, 5U Urogrofin was used to inflate the balloon and this resulted in premature deflation and early electrode displacement in two of the nine patients. When the concentration of Urografin was reduced, the balloon remained inflated for a longer period and the incidence of early displacement was reduced to 8%. However, there was still a late displacement of 8%, Only one wedge‐tipped balloon electrode displaced. This electrode had a faulty sealing mechanism and the balloon could not be adequately inflated. There was a 3% incidence of early and a 3% incidence of late threshold problems with the electrode. However, none of the wedge‐tipped balloon electrodes exhibited this problem.

It was concluded that this new electrode did not fulfill its objectives. The total electrode failure rate, including displacements and episodes of high threshold was approximately 24%.
Ventricular Tachycardia Terminated by Carotid Sinus Massage
Authors: ALBELDA STEVEN M. , MICHELSON ERIC L.
Published: July 2006

Carotid sinus massage affects supraventricular arrhythmias primarily through vagntonic effects on the sinus and AV nodes, but vagal innervation of the ventricle also exists and has been shown to have functional significance. The case presented here illustrates an unusual example of a ventricular tachycardia that was repeatedly converted to normal sinus rhythm by carotid sinus massage following administration of digoxin. The clinician should be aware that a wide QRS‐complex tachycardia that responds to carotid sinus massage is not necessarily supraventricular in origin.
Runaway Pacemaker. A Case Report with a Runaway Rate of 2100 ppm
Authors: INOUE HIROSHI , UEDA KEIJI , OHKAWA SHIN‐ICHIRO , MIFUNE JUN‐ICHIRO , SUGIURA MASAYA
Published: July 2006

A case of runaway pulse generator is described. A Vitalith C‐23 developed runaway on the 13th postoperative day, without any preceding changes in the rate or amplitude of the pulse generator spike. The rate of runaway was 2100 pulses per minute (ppm), one of the highest rates ever reported. The ventricle was not captured by the runaway pulse generator, but was paced effectively by a temporary demand pacemaker (Medtronic 5880A) which was left in case of displacement of the implanted pacing lead. The reasons why the temporary pacemaker was not inhibited are discussed.
Pacing‐Induced Alternate Wenckebach Periods: Incidence and Clinical Significance
Authors: LÉVY SAMUEL , POUGET BERTRAND , CLEMENTY JACQUES , BEMURAT MARC , BRICAUD HENRI
Published: July 2006

Alternate Wenckebach periods have been defined as episodes of 2:1 atrioventricular (AV) block in which conducted P waves exhibit progressive JH prolongation until two or three successively blocked P waves. Ocurrence of this phenomenon during atrial pacing has been established. 7'xshirty‐six patients were studied and right atrial pacing was achieved at increasing rates up to 350 beats/min in order to induce alternate Wenckebach periods. His bundle recordings were obtained in every patient. The patients were subdivided into three groups according to the AV nodni conduction time (AH interval): normal AH (75‐130 ms) was present in 15 patients, short AH (70 ms) in 13 patients and prolonged AH (130 ms) in eight patients. Alternate Wenckebach periods were observed in 29 patients (80.5%). In every patient alternate Wenckebach periods occurred at the AV node level. Atrial pacing failed to induce alternate Wenckebach periods in seven patients, six of whom belonged to the short AH group. In four patients 3:1 block never appeared because of block at the atrial level. Two patients presented 2:1 and 3:1 intrahissian block without significant AH prolongation. The remaining patient developed atrial fibrillation. Alternate Wenckebach periods were observed in six of nine patients after intravenous atropine. This study suggests: 1. pacing‐induced alternate Wenckebach periods at the AV node level are a physiologic phenomenon; and 2. total or partial bypass (or accelerated A V conduction) atrial refractoriness or vulnerability or block at a lower level may prevent its occurrence.
Air Entrapment as a Cause of Transient Cardiac Pacemaker Malfunction
Authors: KREIS DAVID J. , LICALZI LUKE , SHAW RICHARD K.
Published: July 2006

Air within a pacemaker pocket may cause transient malfunction of a replacement unipolar cardiac pacemaker. This was noted in a patient in whom entrapped air prevented tissue contact of the anode, resulting in complete cessation of myocardlal stimulation and absence of an electrocardio‐graphic pacemaker artifact, Methods for avoiding this complication are proposed.
Mode of Operation Induced by Rapid External Chest Wall Stimulation in Patients with Normally Functioning QRS‐Inhibited (VVI) Pacemakers
Authors: CASTELLANOS AGUSTIN , BLOOM MARTIN G. , SUNG RUEY J. , ROZANSKI JOHN J. , MYERBURG ROBERT J.
Published: July 2006

The effects of rapid external chest wall stimulation were evaluated in 10 patients with normally‐operating unipolar, lithium‐powered, QRS‐inhibited pacemakers functioning in their control VVI (QRS‐inbibtted) mode. Stimuli delivered at slow rates resulted in the expected pacemaker inhibition, On the other hand, during rapid (greater than 900/min) external chest wall stimulation, 8 pacemakers reverted to a VOO mode, 1 to a VVI mode and 1 to either a VVI or VOO mode. No pacemaker was totally inhibited by rapid chest wall stimulation. In accordance with the manufacturer's specifications, the rate to which the implanted pacemakers reverted during the VOO modes produced by the fast external stimuli were the same as those of the VOO modes induced by proper application of an external magnet.

Although rapid external chest wall stimulation proved to be a safe procedure, more studies are necessary to determine its usefulness in the follow‐up of patients with implanted QRS‐inhibited (VVI) pacemakers, At present, conclusions cannot be drawn regarding whether these pacemakers will revert to a mode of operation similar to that induced by rapid external chest wall stimulation when subjected to extrinsic sources of strong electromagnetic interference. (PACE, Vol. 2, January‐February, W79)
Pacing Failure Due to an Unusual Fracture of the Sutureless Myocardial Electrode
Authors: KHAIR GAMIL Z. , TRISTANI FELIX E.
Published: July 2006

A 64‐year‐old man had an epicardial demand pacemaker implanted for treatment of Mobitz type II heart block. Two sutureless myocardial electrodes were inserted, but a unipolar system was used based on stimulation threshold and sensitivity measurements. Fourteen months later the patient presented with pacing failure caused by a fracture of the corkscrew electrode with wide separation of the broken ends. The pacemaker, however, continued to inhibit satisfactorily. Pacing was successfully reestablished employing the second available lead. To our knowledge, there has been no publication reporting this type of failure of the sutureless myocardial electrode.
The Recessed Chest Wall Pacemaker Pocket
Authors: GIBBONS JAMES A. , DEVIG PATRICK M. , AARON BENJAMIN L.
Published: July 2006

The recessed chest wall pacemaker pocket. Recurrent pouch problems led to the development of a recessed chest wall pacemaker pocket. Segments of the seventh and eighth ribs were resected in the mid‐axillary the resulting in a “tailor‐made” space suitable for generator implantation, Follow‐up at one year has proven the chest wall to be a satisfactory alternative site for a pacemaker pocket. (PACE, Vol. 2, January‐February, 1879)
Electrograms from the Coronary Sinus in Acute Myocardial Infarction: Implications for Electrocardiographic Guidance of Pacing Catheters
Authors: WALLACE WAYNE A. , NAPODANO RUDOLPH J. , MATHEW P.K.
Published: July 2006

Intracardiac dectrocardiography has been reported to be the most reliable of the techniques used for guiding placement of transvenous pacing catheters. When a catheter electrode is in contact with the right ventricular apical endocardium, the intracordiac electrogram demonstrutes marked ST segment elevation and, usually, a very large S wave. The case presented indicates that both of these features of the intracardiac electrogram should be sought since ST segment elevation alone may represent epicardid recording of an acute myocardial infarction when the catheter electrode is in the coronary venous system.
Dual‐demand Pacing for Refractory Atrioventricular Re‐entry Tachycardia*
Authors: CURRY PAUL V.L. , ROWLAND EDWARD , KRIKLER DENNIS M.
Published: July 2006

An automatic dual‐demand pacemaker has been used in six patients to treat refractory attacks of paroxysmal re‐entry atrioventricular tachycardia that occurred in the Wolff‐Parkinson‐White syndrome. The pacemaker was designed to pace at a fixed rate of 70 beats per minute when sensed heart rates were either below this rate or above 150 beats per minute; in the latter case, it would compete with the paroxysmal tachycardia and interrupt it after a short period of random scanning. The best location for the permanent pacing electrode and the feasibility of using the pacemaker were tested in each case during a detailed preliminary intracardiac electrophysiological study. The permanent pacing electrode was positioned in the coronary sinus in three patients and was attached to the epicardium of either the left or right ventricle in another three. All patients were given regular oral doses of verapamil or propranolol to enhance the effectiveness of the pacemaker system and, with the latter, to prevent pacemaker activation during sinus tachycardia. Over a follow‐up period of between 11 and 47 months, the pacemaker system remained completely effective in three patients, but developed unreliable sensing in another two (one coronary sinus and one left ventricular lead). In the sixth patient the pacemaker was only effective when the rate of the tachycardia remained below 170 beats a minute, as when she was resting supine; when sitting or standing, however, her tachycardia rate considerably exceeded this value and the pacemaker was ineffective. Explanation of the pacemaker and either successful cryosurgical ablation of the accessory AV pathway or treatment with amiodarone was undertaken in the three patients in whom the pacemaker had failed.
Pre‐P (Sino‐Atrial Node Region) Activity Recording from the Right Atrial Cavity by Signal Averaging*
Authors: STOPCZYK MARIUSZ J. , WAJSZCZUK WALDEMAR J. , ZOCHOWSKI RYSZARD J. , RUBENFIRE MELVYN
Published: July 2006

A mobile instrumentation and noninvasive method developed recently for external His bundle recording and employing the signal averaging technique was applied for intraatrial recording of the pre‐P (sino‐atrial node region) activity. Recordings were obtained in ten anesthetized dogs and five patients at the time of right heart catheterization. A bipolar intra‐atrial lead was used for triggering of the averaging process and a unipolar intra‐atrial lead was used for signal recording. Direct bipolar epicardiol recordings were obtained for comparison from the sino‐atrial (S‐A) node area in experimental animals. In animal studies, the averaged intra‐atrial recording showed 30 μV amplitude deflections beginning 40–45 ms prior to the onset of P wave and were preceded by a slow rise and lower frequency and amplitude deflections arising 60–70 ms earlier. There was good correlation between the pre‐P activity recorded intra‐atrially and from the epicardium. Deflections of similar configuration but smaller amplitude (1 μV) were recorded in human studies. They preceded the onset of large atrial activity deflections (P wave) in the reference electrocardiogram by 40–80 ms. The exact source of these pre‐P activity potentials has not been definitely established, but they appear to originate from the S‐A node region, based on their similarity to the direct epicardial recordings and time relationship to the preceding T and following P wave.
Pitfalls in Measuring R Waves in Pacemaker‐Dependent Patients
Authors: WIDMANN WARREN D. , EDOGA JOHN K. , THOMAS LUCILLE , TROTTA JAMES J. , MUCCIONE STEPHEN
Published: July 2006

Determinali'on of adequate R wave sensing is an important step in pacemaker electrode implantation and pacemaker replacement operations. In palients who are completely pacemaker dependent, these operations are usually performed with a functional temporary pacemaker in place throughout the testing period. In such patients, there is the special problem of determining whether the test system is sensing the temporary pacemaker spike rather than the resultant QRS voltage. Patients were studied and a laboratory model was created to evaluate the response characteristics of a standard R wave test device. Patients showed two general types of curves as R waves were measured at various output voltages of the temporary pacemaker. Type A responses showed direct correlation between output voltage and measured R waves. Type B responses showed an initial high plateau of R waves followed by an abrupt fall below acceptable values, and then a direct correlation between R waves and output voltage. Laboratory testing revealed that the temporary pacemaker spike, and not the R wave, was being “sensed” in Type A curves, and that the R wave was sensed only in the initial plateau of the Type B curves. This pitfall can lead to acceptance of an unsatisfactory electrode position in some patients and to futile electrode repositioning in others.
Recurrent Pulmonary Emboli Secondary to Right Atrial Thrombus Around a Permanent Pacing Catheter: A Case Report and Review of the Literature
Authors: KINNEY EVLIN L. , ALLEN ROBERT P. , WEIDNER WILLIAM A. , PIERCE WILLIAM S. , LEAMAN DAVID M. , ZELIS ROBERT F.
Published: July 2006

A case report and review of the literature.

This report describes the management of a woman with multiple pulmonary emboli secondary to a large right atrial clot which had formed around her permanent trans‐venous pacemaker. She continued to have pulmonary emboli despite adequate anti‐coagulation. Removal of the catheter and pacing required right atriotomy under cover of cardiopulmonary bypass, Additionally, eight English language case reports of symptomatic pericatheter thromboses are reviewed. In these cases, pericatheter clot resulted either in right‐sided inlet obstruction or pulmonary emboJi. The mortality rate was 75%. Although the cause for our patient's thromboembolic events is uncertain, congestive heart failure was a predisposing factor in 75% of the other reported cases. We suggest that pacemaker patients in congestive heart failure might benefit greatly from chronic anticoagulation.
Diagnostic Implications of Atrial Vulnerability*
Authors: ENGEL TOBY R. , LUCK JERRY C. , LEDDY CHERYL L. , GONZALEZ ANA DEL C.
Published: July 2006

Extrastim‐ulution in the atrial vulnerable zone may result in atrial fibrillation or flutter (AFF), especially with stimulation of multiple atrial sites. However, the clinical relevance of such vulnerability to AFF is unknown. Therefore, single twice‐threshold extru‐stimuli were applied at three disparate right atrial sites in 45 consecutive unmrdi‐cated patients without overt heart failure. Group I consisted of 12 patients with documented spontaneous paroxysms of AFF. AFF was duplicated in 9 of 12 patients using extraslimulation in the vulnerable zone (5 in sinus rhythm, 4 requiring atrial pacing at 120 beats/min/. Croup II consisted of 33 patients without documented AFF despite monitoring. Vulnerability to AFF was found in 12 of 33 patients (4 in sinus rhythm, 8 requiring atrial pacing). The duration of induced AFF did not discriminate between the two groups. Among the 12 Group II patients vulnerable to AFF, 3 had rapid palpitations, 2 had undiagnosed rapid tachycardias, 1 had atrial tachycardias and 1 junctional tachycardias. In vulnerable patients, the pause after AFF correlated with the pause after atrial pacing, but only 1 of 11 Group II patients with sick sinus syndrome was vulnerable. Thus, paroxysmal AFF may be duplicated with the extruslimulus technique if sufficient arial sites are stimulated, providing a model for evaluation of these arrhythmias. But atrial vulnerability, even to extra‐stimulation at normal heart rates, may be seen in patients suspected of atrial tachy‐arrhythmic in the absence of documented AFF, and does not contribute to the diagnosis of sinoatriul dysfunction.
Intravenous Disopyramide Phosphate and Ventricular Overdrive Pacing in the Termination of Paroxysmal Ventricular Tachycardia
Authors: CAMM J. , WARD D. , WASHINGTON H.G. , SPURRELL R.A.J.
Published: July 2006

Both antiarrhythmic drugs and bursts of rapid ventricular pacing provide alternatives to DC cardioversion for the treatment of paroxysmal ventricular tachycardia. This report considers the individual and combined success of burst ventricular pacing and intravenous disopyramide phosphate in the treatment of 11 examples of paroxysmal ventricular tachycardia. Rapid ventricular pacing, at a rate of up to 50 beats/min faster than the tachycardia rate terminated 7 of the tachycardias. Intravenous disopyramide resulted in increased tachycardia cycle length (342 ± 34 ms‐385 ± 56 ms), increased QRS complex width (147 ± 42 ms‐180 ± 41 ms) and termination of 8 of the tachycardias. The remaining 3 tachycardias could be terminated by bursts of ventricular pacing following the infusion of disopyramide. Of these, 2 could not be terminated prior to disopyramide. The use of both techniques allowed the extinction of all 11 tachycardias and prevented the need to proceed to DC conversion.
Polarization Properties of Small‐Surface‐Area Pacemaker Electrodes—Implications on Reliability of Sensing arid Pacing*
Authors: FISCHLER HENRYK
Published: July 2006

FISCHLER, H. Polarization properties of small‐surfece‐area pacemaker electrodes—implications on reliability of sensing and pacing. The polarization characteristics of Pt‐Jr and Elgiloy small‐surface‐area (10–12.5 mm2) pacemaker electrodes were studied at AC linear (sensing) and DC non‐linear (pacing) conditions. The electrodes’ AC polarization impedance was approximately equal to the demand pacemaker's input impedance, which causes waveform distortions of the sensed R‐wave potentials. The pacemaker's coupling capacitor adds to the distortion's effect. As a result of amplitude attenuation (up to ∼50%) and slew rate changes, the pacemaker may fail to recognize the ventricular complexes, reverting to hazardous competitive pacing. The impact of the DC polarization elements and of the coupling capacitor on the effectiveness of pacing was examined. The deficiency of small area electrodes was pointed out, this being counter‐balanced to some extent by their lower pacing thresholds. The necessity to ensure a sufficient safety margin between the pacing pulse and the stimulation threshold, to avoid possible reasons for creation of exit blocks, was stressed. In reducing the electrode surface, it is advisable not to step down below a 15–20 mm2 effective area for Pt‐Fr, and a 40–50 mm2 area for Elgiloy.
Comparison of Active and Passive Adhering Leads for Endocardial Pacing*
Authors: FURMAN SEYMOUR , PANNIZZO FRANK , CAMPO IVON
Published: July 2006

The frequency of lead failure requiring invasive correction in a total of 276 implants of four different transvenous leads (6907, continuous lead, IE‐65‐1, and MIP 2000) was observed during a one‐and‐one‐half year period with a minimum of two months follow‐up post‐implant. Implants were on a successive sequential basis, randomly distributed between the two surgeons normally performing implants, and unselected for presumed ease or difficulty of the procedure. Failure rates with the 6907 and continuous leads were 7 of 76, or 9.2%; with the IE‐65‐1, 2 of 76, or 2.6%; and with the MJP 2000, 8 of 45, or 17,8%. The difference between the IE‐65‐1 and the two conventional leads was significant at the 5% level, and between the IE‐65‐1 and the group of the other three at the 1.6% level. The MIP 2000 was significantly different from the other three leads at the 2.7% level. Previous clinical experience with 849 implants with continuous and 6907 leads indicated that the overall data was similar to that obtained’ in the present evaluation. No significant differences in failure rates between surgeons and no measurable “practice effect” could be detected. It was concluded that the design of the lead is a major factor in the differing need for early secondary intervention.
Preliminary Experience with the Helifix Electrode for Transvenous Atrial Implantation
Authors: EL GAMAL MAMDOUH , VAN GELDER BERRY
Published: July 2006

A Helifix electrode was inserted transvenously in the right atrial appendage for temporary atrial stimulation in three patients. The low stimulation threshold as well as the excellent stability of the electrode encouraged us to proceed to permanent implantation of this lead in thirteen patients. The lead was introduced through the saphenous vein in twelve patients and through the cephalic vein in one patient. Five patients had sinoatrial dysfunction and five had hradycardia‐tachycardia syndrome; they received atrial demand pacemakers. Two patients had atrioventricular block and received atrial synchronous ventricular pacemakers. Our lasl patient had restrictive cardiomyopalhy, heart failure and a drug‐refractory atrial arrhythmia. She received a dual‐chamber sequential pacing device. Atrial eleclrode displacement occurred in one patient soon after implantation. The lead was promptly repositioned without difficulty. Partial sensing of spontaneous P waves was observed in two patients. One recovered spontaneously, the second after substituting a pulse generator with a higher input sensitivity. Our clinical experience during the period from November IM77 to January 1979 has shown thai the Helifix electrode is suitable for transvenous ufrial implantation.
Escape Rhythm in Complete A‐V Block. The Recovery Phase after Overdrive Suppression from Artificial Ventricular Pacing
Authors: GRENDAHL HELGE , KJEKSHUS JOHN , SOYLAND EINAR , SIVERTSSEN EGIL
Published: July 2006

The recovery phase after overdrive suppression from artificial ventricular pacing. In 60 patients with third degree A‐V block, recovery of escape rhythm from overdrive suppression after ventricular pacing has been studied. Implanted unipolar VVI pacemakers were inhibited by chest wall stimuli. A total of 165 rhythmograms were studied. In 37, the rate was irregular, in the other 128 the escape rate increased gradually, following an exponential curve until stabilization after 3 minutes. In 29 of these rhythmograms, a possible exit block of the first escape impulse was observed. In 99 rhythmograms without exit block, escape rhythm recovery time was on an average 1.45 times basal escape RR intervals. Overdrive suppression was most marked in patients with a slow escape rhythm.
Complications of Defibrillation With Permanent Pacemaker in Situ
Authors: AYLWARD PHILIP , BLOOD RICHARD , TONKIN ANDREW
Published: July 2006

A permanent demand pacing generator was impJanted in the right delto‐pectoral fossa with unipolar transvenous lead advanced to the right ventricle. Implant and subsequent pacing parameters were normal. Five days later an emergency DC cardioversion was performed with one paddle 2 inches from the generator. Cardioversion was followed by failure of QRS‐sensing and, at immediate explant, rise in stimulation threshold. The pulse generator showed end‐of‐life characteristics. The patient died 4 days following replacement of the generator and lead. At autopsy, right ventricular infarction was found, presumably relating to currrent discharge along the lead. Pacemaker analysis showed damage to the protection zener diode and oscillator integrated circuit of the generator during cardioversion.
Similar QRS Morphology in Sinus Rhythm and Ventricular Tachycardia
Authors: HAROLD S. SERGE , ROSS DAVID L. , VOHRA JITU K. , SLOMAN J. GRAEME
Published: July 2006

A 74‐year‐old man with coronary artery disease and bifascicular block suffered from recurrent tachycardia. Although the similarity of QRS morphology in tachycardia and sinus rhythm suggested a supravenlricular origin, His bundle electrocardiography and programmed stimulation showed a ventricular origin. Digitalis toxicity was not an etiological factor and there was no evidence to suggest a His bundle tachycardia. The case illustrates that in occasional circumstances the onset of ventricular tachycardia may produce no change in QRS morphology thus malting the diagnosis by conventional electrocardio‐graphic criteria difficult.
Of Pacemakers and Statistics: The Actuarial Method Extended
Authors: DUSSEL JAN , WOLBARST ANTHONY B. , SCOTT‐MILLAR ROBERT N. , OBEL ISRAEL W.P.
Published: July 2006

Pacemakers cease functioning because of either natural battery exhaustion (nbe) or component failure (cf). A study of four series of pacemakers shows that a simple extension of the actuarial method, so as to incorporate Normal statistics, makes possible a quantitative differentiation between the two modes of failure. This involves the separation of the overall failure probability density function PDF(t) into constituent parts pdfnbe(t) and pdfcf(t). The approach should allow a meaningful comparison of (he characteristics of different pacemaker types.
Multiform Ventricular Tachycardia
Authors: ROSS DAVID L. , HAMER ANGAS W.F. , VOHRA JITU K. , SLOMAN J. GRAEME , HUNT DAVID
Published: July 2006

Electrophysiological studies were performed in three patients with chronic recurrent ventricular tachycardia (VT) associated with coronary artery disease. In each case the ventricular origin of the tachycardia was confirmed and induction of tachycardia by programmed stimulation suggested a re‐entry mechanism. Multiple types of ventricular tachycardia were observed which differed in cycle length, QRS morphology, timing of local epicardial and endocardial ventricular electrograms and the use of the specialized conduction system for propagation. There was evidence of one or more re‐entry circuits arising in or near previously infarcted areas, with features of cycle length alternation, change in exit points and variations in subsequent conduction through the myocardium and specialized conduction tissues. These findings suggest multiform VT can be due to a number of factors. A modified surgical approach is recommended for management of medically refractory VT when there is evidence of multiple types.
Charge Levels in Programmable Pacemakers
Authors: MORSE DRYDEN , SPAGNA PASCHAL , LEMOLE GERALD M.
Published: July 2006

The method of calculation of charge in one series of programmable pacemakers is described. Accurate charge tables are constructed and examples of their use are given. With the tables the margin between the threshold and the pacemaker setting can be more precisely determined and consequently, at least in some cases, it can be reduced for greater pacemaker longevity.
Demand Failures Occurring during Permanent Pacing in Patients with Serious Heart Disease
Authors: OHM OLE‐JÖRGEN
Published: July 2006

Demand failures during permanent cardiac pacing were studied in four patients with coronary heart disease and cardiomyopathies, by means of in vivo and in vitro analyses of the pacemaker system. A common feature of the electrogram analyses (except during a second replacement in one patient), was extremely low values of amplitudes (0.77–4,36 mV) and maximum derivatives (0.16–1.06 V/sec). In spite of low electrogram amplitudes, the myocardial threshold values were low in all patients. An attempt in one patient at unipolarizing a bipolar system made the adaptation between electrogram and pulse generator more difficult. Autopsy showed that the tip of the bipolar electrode was positioned in a fibrotic area of the myocardium. The signal available for the‐sensing circuit will also be reduced because of voltage division between the electrode/tissue interface impedance and the input impedance of the pulse generator. Although the pulse generators used had a high input impedance (10–50 KΩ), the tissue interface impedance may have caused a further reduction in the electrogram amplitude of 10‐30%, This may have contributed to demand failure. In vitro studies confirmed that test pulses with characteristics similar to those of the electrograms found in this investigation, were inadequate for pacemaker inhibition. Special care should be taken during electrogram recordings in patients with severe myocardial disease. One should consider the implantation of a high sensitivity pulse generator or the recently introduced sensitivity programmable pulse generators as first choice for this group of patients.
Presumptive Tricuspid Valve Malfunction Induced by a Pacemaker Lead: A Case Report and Review of the Literature
Authors: GIBSON THOMAS C. , DAVIDSON ROBERT C. , DESILVEY DENNIS L.
Published: July 2006

A 23‐year‐old woman developed 3° AV block with syncope. Insertion of a permanent pacemaker lead was followed by the onset of a persistent murmur in late systole preceded by single or multiple clicks. The murmur was best heard at the left sternal edge, grade 3–4/6 with two major frequencies (60–250 Hz), increased with inspiration and on assuming the erect posture. It was considered to be tricuspid in origin and related to interference of the tricuspid valve apparatus by the pacemaker lead resulting in tricuspid regurgitation. No tricuspid valve prolapse or flutter was seen on echocardiography. Withdrawal of the pacemaker lead resulted in immediate disappearance of the new auscultatory findings. Review of the literature suggests that the appearance of such a murmur following pacemaker insertion could be associated with later complications in relation to tricuspid valve dysfunction. It is therefore recommended that, under these circumstances, permanent pacemaker leads should be appropriately repositioned.
Catecholamine Induced Double Tachycardia: Case Report in a Child
Authors: BENSON D. WOODROW , GALLAGHER JOHN J. , STERBA RICHARD , KLEIN GEORGE J. , ARMSTRONG BRENDA E.
Published: July 2006

A six‐year‐old girl with syncope in association with atrial flutter‐fibrillation and ventricular tachycardia produced by exercise or emotion is presented. The tachycardias could be reproduced by low‐dose isoprolerenol infusion and were blocked by high dose propranolol therapy. Catecholamine‐induced tachyarrhythmias should be suspected in children with unexplained syncope in association with exercise or emotion.
Permanent Cardiac Pacing with Sutureless Myocardial Electrodes: Experience in First One Hundred Patients
Authors: de FEYTER P.J. , MAJID P.A. , HOITSMA H.F.W. , STROES W. , ROOS J.P.
Published: July 2006

This report concerns our experience with a sutureless myocardial lead which we have used in 103 patients for establishment of permanent cardiac pacing. The electrode was inserted through a subxiphoid approach in all patients. Results to date indicate that this technique compares favorably with the presently popular transvenous technique as far as immediate or long‐term morbidity is concerned. Complications were related entirely to pericardiotomy; no lead failure was seen during a maximum follow‐up period of four years.
Prevention of Intra‐Atrial Reentry by Chronic Atrial Pacing
Authors: LECLERCQ J.F. , ROSENGARTEN M.D. , DELCOURT Ph. , ATTUEL P. , COUMEL Ph. , SLAMA R.
Published: July 2006

The authors describe a cose of so‐called “intra‐atrial reentry,” associoted with sinus node dysfunction. The spontaneous initiation of the tachycardia was always preceded by a sinus pause, and external atrial pacing prevented the appearance of tachycardia. Thus an atrial pacemaker was implanted, and after several months, the atriaJ dysrhythmias disappeared completely, despite interruption of the antiarrhythmic drugs. When a pacemaker dysfunction occurred, the sinus node dysfunction and the tachycardia reappeared. This is analogous with the “incessant” tachycardias seen in the WPW syndrome, and must be differentiated from the usual forms of the sick sinus syndrome which require both a pacemaker and antiarrhythmic drugs.
The Small‐Tined Pacemaker Lead—Absence of Dislodgement
Authors: Mond Harry , Sloman Graeme
Published: July 2006

The Medtronic 6961 unipolar transvenous ventricular lead has four symmetrically placed, small tines that protrude backward just proximal to the tip, and are designed to become entrapped beneath or between right ventricular trabeculae. One hundred leads were implanted. Initially, the leads were more difficult to position at the right ventricular apex as the tines tended lo anchor on intracardiac structures. This was overcome by rotating the lead. The time of negotiating the Jead from right atrium to right ventricular apex averaged 3.1 minutes for all leads. The first 20 procedures averaged 4.2 minutes and the last 20 averaged 2.1 minutes. In this latter group, 11 of the 20 passages took 60 seconds or less. Once adequate positioning was obtained, the lead was retracted using slight tension to demonstrate tip entrapment. There were no lead dislodgements. Eight deaths occurred following institution of pacing and lead dislodgement was not detected in any of these cases. Four patients had complications associated with pacing, two transient diaphragmatic pacing not requiring reoperation, one right ventricular perforation and one raised threshold with intermittent failure of pacing without lead perforation or dislodgement. Because of the absence of dislodgement, this lead appears to have significant advantages over conventional leads.
Autodecremental Pacing—A Microprocessor Based Modality for the Termination of Paroxysmal Tachycardias
Authors: WARD D.E. , CAMM A.J. , GAINSBOROUGH J. , SPURRELL R.A.J.
Published: July 2006

Autodecremental pacing—A microprocessor based modality for the termination of paroxysmal tachycardias. Five patients aged between 27 and 48 years were referred for investigation of recurrent paroxysmal tachycardias. EJectrophysiological studies revealed concealed ventriculoatrial accessory pathways in two patients, possible atrionodal pathways in two patients and dual intranodal pathways in one patient. During electrophysiologicol study, particular attention was paid to methods of terminating tachycardia by pacing techniques including single or double atrial and ventricular extrastimuli, atriaJ or ventricular underdrive, atriaJ overdrive pacing, and in two patients, rapid ventricular pacing. Autodecremental' atrial pacing was employed in all five patients and autodecremental ventricular pacing in two patients. This system is controlled by a microprocessor interfaced with a stimulator. When tachycardia of a cycle length less than 375 ms is sensed the system initiates pacing sequences. The initial stimulus is introduced at an interval less than the tachycardia cycle determined by a preset decremental value D. Each subsequent pacing interval is reduced by the value of D resulting in a gradual acceleration of pacing. The total duration of pacing is limited by the value of the pacing period (P). The final pacing rate is determined by P but cannot exceed 275 bpm (cycle length of 218 ms). Both P and D are operator programmable variables. Tachycardias of a cycle length less than 218 ms do not activate the pacemaker. The postpacing sensing deadtime of the system is set at 50 ms. In three patients, double atrial extrastimuli or atrial overdrive initiated atrial flutter or fibrillation. Autodecremental atrial pacing was successful in converting tachycardia to sinus rhythm in all five patients without initiation of other tachyarrhythmias. Autodecremental ventricular pacing was successful in one of the two patients in which it was used. This new modality of pacing has several theoretical advantages over conventional methods: the decremental mode may avoid stimulation in the vulnerable period and minimizes the rislt of initiating other tachyarrhythmias; gradual acceleration of pacing over a short period results in stimulation at different phases of the tachycardia cycle length; and the operator variables D and P provide a flexible system which may be adjusted to suit a particular patient and tachycardia. The development of a fully implantable programmable system is made attractive by the simplicity and adaptability of this technique.
A Clinical Evaluation of an Improved Holler Monitoring Technique for Artificial Pacemaker Function
Authors: KELEN G.J. , BLOOMFIELD D.A. , HARDAGE M. , GOMES J.A. , KHAN R. , GOPALASWAMY C. , EL SHERIF N.
Published: July 2006

This paper discusses shortcomings of conventional Holter monitoring in paced patients and describes a new technique which permits reliable detection of intermittent pacemaker malfunction and counts pacemaker activity during the recording period. Evaluation of the system on 64 consecutive patients revealed is with unsuspected episodic pacemaker dysfunction.
Implantation of Atrial Synchronous Pacemaker with Transvenous Electrodes after Surgery for Hypertrophic Subaortic Stenosis
Authors: BENNETT D.H. , DEIRANIYA A.K.
Published: July 2006

An atrial synchronous ventricular pacemaker was implanted in a patient with hypertrophic subaortic stenosis who developed permanent complete atrioventricular block during Jeft venfriculomyotomy and myectomy. In spite of partial amputation of the right atrial appendage, performed during cannulafion for cardiopul‐monary bypass, a transvenous pacing lead with a helically coiled tip was easily attached to the remnant of the appendage and satisfactory atrial sensing was achieved.
Conversion of Atrial Flutter: Rapid Atrial Pacing as a Bedside Technique
Authors: HENTHORN RICHARD , ROBERTS WILLIAM S. , KELLY KEVIN , LEIER CARL V.
Published: July 2006

Eleven patients with atrial flutter underwent intracardiac right atrial pacing at bedside in an attempt to terminate this dysrhythmia. Nine of the eleven patients were converted to sinus rhythm; the remaining two patients were converted to atrial fibrillation with a slower ventricular rate. There were no complications. The potential hazards of direct current cardipversion (anesthesia, fractures, muscle strain, myocardial injury, etc.) were avoided. In contrast to rapid atrial pacing in the electrophysiology laboratory, the bedside technique did not require a special laboratory setting, electronic or x‐ray equipment, or technical personnel. Transportation of critically ill patients was obviated. Atrial flutter can be converted at the bedside to a more favorable rhythm; the expediency, safety, and low cost of this bedside cardioversion technique not only makes it feasible, but also it is often the procedure of choice.
Carcinoma of the Breast in a Pacemaker Pocket—Simple Recurrence or Oncotaxis?
Authors: MAGILLIGAN DONALD J. , ISSHAK GEORGE
Published: July 2006

An 89‐year‐old female developed recurrent carcinoma of the breast in a pacemaker generator pocket. This is the fourth reported case of the occurrence of tumor in relation to a pacemaker and serves as a stimulus to review possible cause and effect relationships.
Suicide Attempt by Pacemaker System Abuse: A Case Report with Comments on the Psychological Adaptation of Pacemaker Patients
Authors: SIMON ARTHUR B. , KLEINMAN PETER , JANZ NANCY
Published: July 2006

Thirty patients seJected at random from a pocemaker clinic were inter‐viewed to gain an understanding of how psychological symptoms in these patients related to their cardiac condition. In 20% veiled depresslon or even a wish to die was elicited. loking, fantasies, and denial were common psychological mechanisms used to adapt to their illness and the pacemaker itself. A dramatic example of attempted suicide in which the patient tried to cut the subcutaneously implanted pacemaker leads is presented and illustrated.
Cardiac Electrodes and Electrograms: Some New Observations and Concerns
Authors: BROWNLEE ROBERT R. , HUGHES HOWARD C. , TYERS G. FRANK O. , NEFF PAUL H. , DELMARCO CHARLES J.
Published: July 2006

Electrode studies have been performed with dead animal tissue and a variety of other materials immersed in saline solution and compared with studies in the canine heart (live and arrested) in an attempt to delineate both normal and anomalous signals sensed by pacemaker electrodes or obtained during diagnostic electrogram recording of cardiac activity. The data from these studies could be useful for defining the origin of artifacts and a variety of other phenomenon such as “fractured” QRS complexes, acute ST segment elevations, His bundle oscillatory signatures, and unexplained potentials synchronously associated with cardiac events. The studies verify that artifacts can be generated in an electrolyte medium by rubbing electrodes against insulators or biologic materials and by inducing motion between common pole materials of an active electrode system. The studies suggest that some of the grasping electrodes in current clinical use may be subject to self‐generating artifacts associated with cardiac‐induced frictional motion between the constituent materials employed in the electrode design.
Atrial and His Bundle Stimulation with an Accessory Nodo‐Ventricular Connection
Authors: HEDDLE WILLIAM F. , TONKIN ANDREW M.
Published: July 2006

A 39‐year‐old man with a history of frequent paroxysmal tachycardias for 27 years was referred for electrophysiology study. His resting electrocardiogram showed left bundle branch block, which persisted during paroxysmal tachycardia. Electrophysiology study demonstrated the presence of a right‐sided accessory nodo‐ventricular connection.1 The case is of particular importance as it illustrates the diagnostic value of QRS normalization with left atrial pacing and the therapeutic use of rapid His bundle pacing to terminate the tachycardia.
Inhibition/Filter Characteristics and Input Impedances of QRS‐Inhibited Demand Pacemakers Determined by in vitro Studies
Authors: OHM OLE‐JÖRGEN
Published: July 2006

There is stiil no standardized test procedure established for demand pacemakers, Much work has been done to reduce demand failures, but more knowledge is needed to arrive at better results. This study was initiated by in vivo observations of pacemaker malfunctions and unwanted pacemaker effects, the objective being to arrive at a better match between spontaneous cardiac activity and the pacemaker system. The study describes inhibition characteristics and input impedances in some modern temporary as well as permanent QRS‐inhibited puise generators, based on in vitro experiments with various signaJ waveforms. The different puise generators tested showed a wide variety of inhibition characteristics. The interrelationship between signal amplitude and maximum derivative required to obtain pacemaker inhibition is pointed out. A better approach to describe the inhibition characteristics of demand pacemakers seems to be the introduction of the time integral (voltseconds) in‐stead of the maximum derivative of a signa) (Fig. 3). It is shown that this method nearly removed the discrepancies in inhibition characteristics between different puise waveforms used. The input impedances were also widely dispersed and were in some instances of a magnitude so low that it would Jead to marked reduction of the electrogram amplitude in case the electrode/tissue interface impedance was high. The characteristics of temporary puise generators were in several respects different from those of the permanent ones. The results obtained with a temporary unit during a test procedure are therefore not the same as for a permanent pacemaker system.
Fascicular Premature Beats with Narrow QRS in the Presence of Bundle‐Branch Block
Authors: VENKATARAMAN KALYANASUNDARAM , MATHEWS NUR P. , BILITCH MICHAEL
Published: July 2006

The electrocardio‐gram of o sixty‐two‐year‐old male revealed right bundle‐branch block, left anterior superior fascicular bJack, and right precordial Q waves consistent with anteroseplal myocardial infarction. Premoture beats with narrow QRS (100 ms) occurred inter‐miltently; coupling infervals varied between 560–600 ms. His bundle electrogram confirmed the fascicular origin of the premature beats. During otrial prematuring studies, it was shown that an appropriately timed premature beat could prolong infra‐His conduction time, but QRS normalization was not achieved. The possible electrophysiologic mechanisms that could result in a normal QRS complex with fascicular premature beats in this patient are discuased; a new mechanism is sug‐gested.
A New Lead for Transvenous Atrial Pacing and Sensing Clinical and Electrophysiological Experiences
Authors: KRUSE IB , RYDÉN LARS , YDSE BO
Published: July 2006

The Medtronic 6961 lead has been used in 14 patients for transvenous atrial sensing and for pacing. This lead is furnished with small tines of silicons rubber at the distal end. The conductor coil material is space wound for flexibility. Thus, the lead lacks intrinsic elasticity and can be fastened within the right atrial appendage without a preformed J‐shape. The clinical experiences with the lead are encouraging. The lead is easier to introduce and position in the right atrial appendage than the previously used tined J‐shaped leads (Medtronic 6991). The small size of the new lead makes the choice of vein less critical and a normally‐sized external jugular or cephalic vein permits the use of the same vessel for a second ventricular lead. By means of a lead extension wire, consecutive determinations of the P‐wave amplitude, stimulation threshold of the right atrium, electrode resistance, and P/QRS‐ratio were made for four weeks following electrode insertion. The mean P‐wave amplitude at insertion was 4.9 ± 1.5 mV (mean ± SD). There was a significant decrease to a lowest mean level of 309 ± 1.1 mV after one week. From that time there were only small variations. In the supine position and with normal breathing there was a spontaneous variation of the P‐wave amplitude of ± 12%. The P‐wave amplitude was influenced by body position and maximal breathing movements to a minor extent. The threshold of stimulation was 0.9 ± 0.4 V (impulse duration 0.5 ms) at the time of electrode insertion. It increased to 2.4 ± 0.5 V after one week. Later there was a small decrease in the threshold which, however, still remained significantly higher than at the time of insertion. The total resistance of the electrode system was about 700 ohms and P/QRS‐ratio about 4 ± 3. During an observation time ranging from 4 to 11 months there were no electrode dislocations. The electrodes were connected to the intended pacemakers without complications. In conclusion, the transvenous endocardial atrial lead, Medtronic 6961, shows attractive and promising qualities. The electro‐physiological data recorded are suitable for the pacemakers in use. The electrode definitely deserves further evaluation.
Characteristics of Intracardiac Electrograms II: Atrial Endocardial Electrograms
Authors: PARSONNET VICTOR , MYERS GEORGE H. , KRESH YASHA M.
Published: July 2006

The intra‐alriai electrograms (P‐wave and QRS complex) of newly implanted electrodes were recorded, and the time and frequency domain characteristics compared. The sensing impedance properties of the atrial electrode were studied in relation to the characteristics of both atrial and ventricular electrograms, and specific differences between the P and R‐waves were identified. These values, particularly the amplitude and frequency components, were sufficiently distinct to make differentiation by pacemaker sensing circuits selective and reliable.