bluuebunny/crossref_metadata_2025 huggingface dataset:
Conservation Value of Non‐Native Banteng in Northern Australia
Authors: BRADSHAW COREY J. A. , ISAGI YUJI , KANEKO SHINGO , BOWMAN DAVID M. J. S. , BROOK BARRY W.
Published: July 2006

Abstract: The global species extinction crisis has provided the impetus for elaborate translocation, captive breeding, and cloning programs, but more extreme actions may be necessary. We used mitochondrial DNA, Y‐chromosome, and nuclear lactoferrin‐encoding gene sequencing to identify a wild population of a pure‐strain endangered bovid (Bos javanicus) introduced into northern Australia over 150 years ago. This places the Australian population in a different conservation category relative to its domesticated conspecific in Indonesia (i.e., Bali cattle) that has varying degrees of introgression from other domesticatedBosspp. The success of this endangered non‐native species demonstrates that although risky, the deliberate introduction of threatened exotic species into non‐native habitat may provide, under some circumstances, a biologically feasible option for conserving large herbivores otherwise imperiled in their native range.
Addressing Data Deficiency in Classifying Extinction Risk: a Case Study of a Radiation of Bignoniaceae from Madagascar
Authors: GOOD TATJANA C. , ZJHRA MICHELLE L. , KREMEN CLAIRE
Published: July 2006

Abstract:  Of the roughly 12,000 known plant species in Madagascar, only 3% are found in the IUCN (World Conservation Union) Red List of Threatened Species. We assigned preliminary IUCN categories of threat to the species of a comparatively well‐known tribe, Coleeae (Bignoniaceae), which comprises an endemic, species‐rich radiation in Madagascar. Because the IUCN Red List Categories and Criteria 3.1 discourage the use of the data‐deficient category, we developed a novel method for differentiating between range‐limited species and poorly sampled species. We used the Missouri Botanical Garden (MBG) gazetteer to determine where other collection efforts had taken place. We drew buffers around each Coleeae locality and determined how many times the surrounding area had been visited since the last sighting of the specimens by intersecting the buffers with all known botanical localities from the MBG gazetteer. We determined that at least 54% of the Coleeae species are threatened with extinction. Assignments of species to this category were often due to predicted future decline within their current area of occupancy and their lack of inclusion within the protected‐area network (only 42% of species are known to occur in protected areas). Three species were presumed extinct, and an additional 12 have not been seen in decades. Among the species threatened with extinction, we “rescued” six of them from the data‐deficient category by considering both the sample dates and localities of places where they occurred in relation to additional collections that took place in the immediate area. Due to their recent discovery, 15 species remained in the data‐deficient category. If Coleeae is representative of the Malagasy flora, or at least of other endemic‐radiated plant groups, then species loss in Madagascar may be even more extreme than is realized.
Future Ecosystem Services in a Southern African River Basin: a Scenario Planning Approach to Uncertainty
Authors: BOHENSKY ERIN L. , REYERS BELINDA , VAN JAARSVELD ALBERT S.
Published: July 2006

Abstract:  Scenario planning is a promising tool for dealing with uncertainty, but it has been underutilized in ecology and conservation. The use of scenarios to explore ecological dynamics of alternative futures has been given a major boost by the recently completed Millennium Ecosystem Assessment, a 4‐year initiative to investigate relationships between ecosystem services and human well‐being at multiple scales. Scenarios, as descriptive narratives of pathways to the future, are a mechanism for improving the understanding and management of ecological and social processes by scientists and decision makers with greater flexibility than conventional techniques could afford. We used scenarios in one of the Millennium Ecosystem Assessment's subglobal components to explore four possible futures in a Southern African river basin. Because of its ability to capture spatial and temporal dynamics, the scenario exercise revealed key trade‐offs in ecosystem services in space and time and the importance of a multiple‐scale scenario design. At subglobal scales, scenarios are a powerful vehicle for communication and engagement of decision makers, especially when designed to identify responses to specific problems. Scenario planning has the potential to be a critical ingredient in conservation as calls are increasingly made for the field to help define and achieve sustainable visions for the future.
An Integrated Approach to the Business Cycle
Authors: Kapp K. William
Published: July 2006

Die Konjunkturschwankungen: Theoretische Gunglagen der Wirtschafts‐politik, Bd. II.

The Japanese Village in Transition. By A. F. Raper, T. Tsuchiyama, H. Passin and D. L. Sills.

Public Finance and Fiscal Policy. By Richard W. Lindholm.

Business and Government. By C. C. Rohlfing, E. W. Carter, B. W. West and J. G. Hervey.

The Economy of Latin America. By Wendell C. Gordon.

Price Theory. By Sidney Weintraub.

Pricing in Planned Economy. By B. V. Krishnamurti.

Pressure of Population and Economic Efficiency in India. By D. Ghosh.

Studies in Genius. By Walter G.
The Concept of ‘Ecological Complex’: A Critique*
Authors: Willhelm Sidney M.
Published: July 2006

Abstract. This paper presents certain distinct and fundamental short comings contained in ecological explanations that rely upon physical variables. The limitations stem from the continuation of impersonal notions and questionable analytical premises.
Art Content and Economic Reality
Authors: Kavolis Vytautas
Published: July 2006

Summary.— As a partial test of the Marxist sociology of art, selected evidence on the relationship between economic conditions and art content in a wide range of cultures is analyzed. The analysis reveals that (a) economic conditions are reflected in some kinds of art content, but (b) the main determinants of the reflection of economic conditions in art content seem to be emotional involvements (positive or negative) with aspects or objects of the economy.
Opportunity, Subculture and the Economic Performance of Urban Ethnic Groups
Authors: Katzman Martin T.
Published: July 2006

Abstract. An attempt is made to account for age‐specific differences in economic performance among 14 ethnic groups living in the nation's nine largest metropolitan areas, by regression analysis of 1950 U.S. Census data. A large proportion of the variance in occupational structure, income, unemployment, and labor force status is accounted for by variations in urban opportunities, relative group size and the members' educational attainment. With the specified economic factors held constant, ethnic factors—nationality and nativity—are associated with residual differences in economic performance. These residual ethnic influences as well as ethnic differences in marital, educational, and labor force status suggest that differences in ethnic subculture have important economic consequences.
Peddling in the Antebellum Economy: Precursor of Mass‐Marketing or a Start in Life?
Authors: Uselding Paul J.
Published: July 2006

Abstract. This article examines the effect of peddling upon industrialization and economic development and the evolution of institutional arrangements in marketing in the Antebellum period. After 1840 peddling in America was undertaken, to an increasing extent, by newly arrived immigrants from Germany who displaced the traditional “Yankees” from the trade. The relationship between peddling and the development of entrepreneurship is explored, along with the special opportunities that peddling provided for economic and occupational mobility in the American milieu. The frequency with which individuals who started careers as peddlers rose to prominence in the fields of merchandising and finance points to the importance of the “schooling” function of this institution for newly arrived immigrants in American folkways, business practices, and commercial possibilities.
Public Spending, Land Taxes and Economic Growth: An Empirical Analysis of the Adequacy of Land as a Tax Base
Authors: Stone Gerald W.
Published: July 2006

Abstract. Site value taxation is often cited as desirable on efficiency grounds, but is all too often dismissed for alleged lack of revenue potential. This paper empirically tests the revenue adequacy of site value taxation. Revenue adequacy in this study is defined as the ability of the tax base to keep pace with community expenditure needs. The paper concludes that communities with higher than average rates of capital growth and with a relatively constrained land area will find land taxes when subsituted for present property taxes, quite adequate for future as well as present needs.
Development Theory and the Multilateral Development Banks: An Assessment of the Effectiveness of Strategies Used in International Development Finance
Authors: Sanford Jonathan
Published: July 2006

Abstract. Although they are leading institutions in the world of modern development finance, the multilateral development banks have not been very explicit in outlining the development theories upon which they base their loan operations. This paper assesses the utility of the three prime theories employed by these institutions: the project approach, the macroeconomic (gap theory) approach, and the social welfare (or income distribution) approach. It indicates the questions to which each approach addresses itself, and it indicates weaknesses and theoretical inadequacies of each as a primary or sole development tool. Only a balanced and careful use of all these sometimes contradictory approaches will permit the multilateral lending institutions to fulfill their multifaceted obligations.
The Deterrence Effect of Law Enforcement: An Evaluation of Recent Findings and Some New Evidence
Authors: Cloninger Dale O.
Published: July 2006

Abstract. Six attempts to measure the deterrence effect of law enforcement on certain criminal activities, as well as one by the author, have produced no clear, unequivocal evidence to support the belief that increased public expenditures on law enforcement have a deterrent effect on such activity. Yet the effect may exist. Further research into the measurement of the variables crime and enforcement and upon the nature of the relationship between them must be carried on before definite conclusions can be reached about the existence of the deterrence effect.
Performance of Implanted Biogalvanic Pacemakers*
Authors: CYWINSKI JOZEF K. , HAHN ALLEN W. , NICHOLS MICHAEL F. , EASLEY J. ROGER
Published: July 2006

Seventeen unipolar cardiac pacemakers powered by hybrid biogalvanic cells were implanted in dogs. Long term clinical effects and electrical performance in vivo of the generators were investigated. The biogalvanic cells were designed to provide 50 years of generator operation.

No systemic pathological changes which would be attributed to the generator or the biogalvanic cell were observed. Local reaction to implants was mild and not significantly different from the one observed in conventional pacemaker implantations to date. The electrical performance of the biogalvanic cells was very encouraging. Final steady‐state cell voltage levels of .65V to .75V were reached in 100–150 days after implantation and remained constant in 3 units to date which represents over 36 months after implantation for each generator.
Suppression of Demand Mechanism by Inactive Myocardial Electrodes
Authors: YOKOYAMA MASAYOSHI , HORI MOTOKAZU , GRECHKO MICHAEL
Published: July 2006

A 14 year old girl, at age 8, had had a bipolar pulse generator implanted with myo‐cardial leads. Because one of the myocardial leads fractured near the electrode, a second pair of myocardial leads were implanted. Thus, the patient had two pairs of myocardial leads and one demand pulse generator implanted.

When the patient was readmitted to the hospital because of light‐headedness, the ECG monitor revealed frequent suppression of pulse generator pulses when hand pressure was exerted over the pulse generator site. Converting the pulse generator into the asynchronous mode with a magnet prevented inhibition. The pacemaker pocket was reopened. The pulse generator could not be inhibited either by pulling on the active myocardial leads or by moving the pulse generator, but the pulse generator could be inhibited by manipulation of the inactive leads which produced electrical signals having amplitudes and frequencies which were in the bandwidth of the sensing circuit. The probable cause of the electrical signals was the irregular conta of the terminals of the inactive leads with the patient's abdominal muscles. Replacement of the demand pulse generator by an asynchronous type resulted in cessation of the patient's light‐headedness.
Evaluation of a Rechargeable Pacemaker System
Authors: STERTZER SIMON H. , DEPASQUALE NICHOLAS P. , CORN LAWRENCE J. , BRUNO MICHAEL S.
Published: July 2006

A rechargeable‐demand nickel‐cadmium pulse generator for permanent transvenous cardiac pacing was evaluated in 66 patients. During a cumulative follow‐up period of 2,333 patient months (194.4 patient years), failure of the pacing circuit occurred in 3 patients at 21, 25, and 27 months, respectively. Nine patients had difficulty accepting the recharging concept and, in 3 of these patients, it became necessary to replace the rechargeable generator with a conventional energy source. The overall failure rate of approximately 3% per year (including the 3 patients in whom it was necessary to remove the generator because of failure to recharge properly), coupled with the inconvenience of recharging, limits the usefulness of the rechargeable system compared to the newer lithium‐powered generator.
Partial Pacemaker Recycling of Implanted QRS‐Inhibited Pulse Generators
Authors: SUNG RUEY J. , CASTELLANOS AGUSTIN , THURER RICHARD J. , MYERBURG ROBERT J.
Published: July 2006

In the evaluation of twenty‐three patients with implanted QRS‐inhibited lithium‐powered pulse generators (Intermedics C‐MOS‐1 and ARCO L1‐2D), we repeatedly observed the phenomenon of partial pacemaker recycling (PPR), in which the escape interval induced by a premature ventricular beat is shorter than the automatic interval (AI). In order to determine the sensing properties of these pulse generators, programmed chest wall stimulation (CWS) was systematically performed in all 23 patients and, in addition, intracardiac programmed ventricular stimulation (PVS) via temporary intravenous pacing catheters was performed in 9 of them. The AI of these pulse generators ranged from 820 to 860 msec and absolute refractory periods (ARP) from 220 to 330 msec. Precise correlation in determining pacemaker sensing properties could be demonstrated between CWS and PVS. The phenomenon of PPR occurred 110 to 240 msec following ARP with both CWS and PVS, and appeared to be time‐ rather than voltage‐dependent. We conclude that: (1) CWS is a safe, simple and accurate method for studying pacemaker sensing properties, and (2) time‐dependent PPR is a normal electrical feature of certain implanted QRS‐inhibited lithium‐powered pulse generators.
An Unusual Form of the Bradycardia‐Tachycardia Syndrome: Paroxysmal A‐V Block and Ventricular Tachycardia
Authors: LISTER JOHN W. , GOSSELIN ARTHUR J. , SWAYE PAUL S.
Published: July 2006

An unusual case of alternating bradycardia‐lachycardia, paroxysmal Mobitz 11 A‐V block and ventricular tachycardia is described. The patient presented with a normal resting (control) electrocardiogram and intracardiac conduction times (A‐H and H‐V intervals). The clinical evaluation, electrophysiology, and importance of defining the cause of serious rhythm disturbances prior to therapy are discussed.
Periodic Pacemaker Spike Attenuation with Preservation of Capture: An Unusual Electrocardiographic Manifestation of Partial Pacing Electrode Fracture
Authors: BAROLD S. SERGE , SCOVIL JAMES , ONG LING S. , HEINLE ROBERT A.
Published: July 2006

This report describes the electrocardiograms of a patient with an intermittent electrode fracture presenting with periodic attenuation of the pacemaker spike without loss of ventricular capture. There was infrequent prolongation of the spike‐to‐spike interval probably because the pulse generator interpreted random false signals as interference and reverted to its fixed‐rate mode. These observations add to the spectrum of electrocardiographic abnormalities of electrode malfunction.
Permanent Cardiac Pacing in Infants and Children
Authors: WILLIAMS W.G. , IZUKAWA T. , OLLEY P.M. , TRUSLER G.A. , ROWE R.D.
Published: July 2006

This clinical review details our 15 year experience with permanent cardiac pacemakers in 81 infants and chiJdren. Pacing was found inappropriate in one infant. The other 80 patients were paced because of congenital heart block (24), post‐operative block (50), or sick sinus syndrome (6). Maintenance of long‐term pacing requires all too frequent re‐operation for battery depletion (37%), lead related problems (32%) or wound dehiscence (31 %). Problems related to pacemaker size and the presence of a high myocardial threshold are particularly important in (he pediatric patient. In spite of these problems, children requiring cardiac pacemakers can be extremely well, their prognosis depending almost entirely on the presence of underlying heart disease.
Symptomatic Improvement in a Patient with Sick Sinus Syndrome After the Onset of Stable Atrial Flutter
Authors: KLEINFELD MORRIS J. , BOAL BERNARD H.
Published: July 2006

A patient with sick sinus syndrome (SSS) presented with episodic lightheadedness and weakness. The electrocardiographic features were marked supraventricular bradyarrhythmias and paroxysmal atriai flutter. The symptoms lested for four years and disappeared with the onset of stable atrial flutter which has persisted for the past seven years. Over the 11‐year period of observation, there has been progressive involvement of the His‐Purkinje system manifested by the development of left anterior fascicular block, right bundle‐branch block, and prolongation of the HV conduction time. The patient has refused pacemaker implantation, In the absence of angina and in the presence of a normal heart size, the etiology of his SSS is postulated to be idiopathic fibrosis of his conduction system.
Additional Evidence for Re‐entry Within the Bundle Branches in Man
Authors: FOSTER JAMES R. , SIMPSON ROSS J.
Published: July 2006

A repetitive, non‐paced ventricular beat (V3) often occurs during ventricular extrastimulus testing at short coupling intervals when critical retrograde His‐Purkinye conduction delay is achieved. Though re‐entry within the bundle, branches has been proposed as the mechanism for V3. it has been difficult to exclude local re‐entry. In the present case, we consistently recorded a right bundle branch potential as well as a bundle of His potential before each V3. The anterogrude activation sequence of these potentials provides evidence against local reentry and supports re‐entry involving the bundle branches as the mechanism for V3.
Reprogramming of Implanted Pacemaker Following External Defibrillation
Authors: BAROLD S. SERGE , ONG LING S. , SCOVIL JAMES , HEINLE ROBERT A. , WRIGHT THEODORE
Published: July 2006

This report describes reprogramming of a pulse generator consequent to cardiac defibrillation. Analysis of the explunted pulse generator revealed normal function. We tested the electrical properties of several defibrillaiors and our studies suggest that erratic electrostatic discharges at the time of paddle application before defibrillation may create a signal sequence capable of reprogrumming the particular pulse generator by activating either the reed switch or internal electronics.
Apparent Malfunction of Demand Pacemakers due to Spurious Potentials Generated by Contact Between Two Endocardial Electrodes
Authors: WAXMAN HARVEY L. , LAZZARA RALPH , EL‐SHER1F NABIL
Published: July 2006

Malfunction of both temporary and permanent demand transvenous pacemakers was caused by contact between the two endocardial electrodes. Contact between these electrodes created spurious potentials which resulted in irregular inhibition of both demand units. The potentials were demonstrated by recording from the temporary wire. there was no interference with either pacemaker in the fixed rate mode and malfunction ceased when the temporary wire was removed.
Permanent Rapid Atrial Pacing to Control Supraventricular Tachycardia
Authors: PRESTON THOMAS A. , HAYNES ROBERT E. , GAVIN WILLIAM A. , HESSEL EUGENE A.
Published: July 2006

A case is reported of a patient who had continuous supraventricular tachycardia with a ventricular rate of about 170. The arrhythmia was refractory to drugs and DC countershock, and did not convert with atrial pacing. Rapid atrial stimulation controlled the ventricular rate by simulating atrial fibrillation (pacing at 300‐400/min), or by simulating a faster atrial tachycardia with 2:1 conduction (pacing at 205‐210/min), This form of therapy was used on a permanent basis for more than five months. (PACE, Vol. 2, May‐June, 1979)
Sinus Arrest in Diaphragmatic Myocardial Infarction: Treatment of Power Failure with Atrial Pacing
Authors: BURKS JOHN M. , CALDER JOSEPH R. , ROLAND DANIEL L.
Published: July 2006

Sinus arrest occurred in a patient with acute diaphragmatic myocardial infarction assacioted with right ventricular infarction. Cardiac output fell dramatically despite maintenance of a functioned rate of 72. Ventricular pacing at rate 82 and dopamine administration resulted in only slight hemodynamic improvement. Atrial pacing at rate 84 restored normal cardiac output until resumption of sinus node activity. These results suggest that atrial contraction is important for the maintenance of ventricular function in some patients with acute infarction, and may be of particular importance in the presence of right ventricular infarction. Temporary atrial or atrioventricular sequential pacing may be of great hemodynamic benefit in selected patients with conduction defects complicating myocardial infarction.
Ventricular Tachycardia and Ventricular Fibrillation in Patients with Short P‐R Intervals and Narrow QRS Complexes
Authors: MYERBURG ROBERT J. , SUNG RUEY J. , CASTELLANOS AGUSTIN
Published: July 2006

Eleven patients with short P‐R Intervals and narrow QRS complexes had ventricular tachycardia due to organic heart disease: mitral valve prolapse with mitral insufficiency (2 patients); alcoholic (?) cardiomyopathy (2 patients); and coronary artery disease (7 patients). Intracardiac studies showed short A‐H intervals during sinus rhythm in all cases. The onset of ventricular fibrillation (which, to our knowledge, has not been observed in patients having short P‐R and A‐H intervals coexisting with narrow QRS complexes) was documented in 4 cases. Only 1 patient (with quinidine syncope) had been premedicated. In the 3 other patients the episodes of ventricular fibrillation appeared during bouts of atrial fibrillation with rapid ventricular rates which could have been an expression of the “enhanced A‐V conduction” that had been manifested in sinus beats by short P‐R and A‐H intervals. In clinical settings and physiological conditions proven to be hemodynamicaliy unstable (such as transient ischemia or acute myocardial infarction) these rapid ventricular rates could have led to ventricular fibrillation; directly because of the R‐on‐T phenomenon, and/or indirectly due to decreased coronary perfusion. Ventricular tachycardia and ventricular fibrillation due to organic heart disease probably occur more often than suggested by the few reported cases in the literature. Its significance, however, has to be clarified by further prospective studies
Myopotential Inhibition of Demand Pacemakers: Etiologic ‘Diagnostic, and Therapeutic Considerations
Authors: BERGER RICHARD , JACOBS WARREN
Published: July 2006

Myopotential inhibition of demand pacemakers is a common phenomenon and is responsible for a greater degree of morbidity and possible mortality in patients with pacers. Significant electrical potentials generated by contracting muscle mass gain entry into the pacemaker circuitry causing inhibition of pacemaker activity. Intraoperalive and bedside maneuvers can readily precipitate the problem and allow for accurate diagnosis. Holier monitoring frequently can also serve to establish the diagnosis. Pacemaker repositioning, replacement with a bipolar system, use of a fixed‐rate pacemaker, and pacemaker “sleeves” are possible intraoperative therapeutic methods. External sensitivity adjustable pacemakers would seemingly allow for noninvasive solutions to the problem.
Spectral Properties of Atrial and Ventricular Endocardial Signals
Authors: KLEINERT M. , ELMQVIST H. , STRANDBERG H.
Published: July 2006

The spectral energy distributions of signals picked up by endocardial, atrial and ventricular electrodes have been investigated. The results show similar spectral distributions for P‐waves and QRS‐complexes with maximum spectral densities at frequencies between 10 and 30 Hz.
A Microcomputer‐based Stimulator for Clinical and Experimental Investigations in Cardiac Electrophysiology*
Authors: BILLETTE JACQUES , GUARDO ROBERT , BERTRAND MICHEL , LAFORTUNE MICHEL , ROBERGE FERNAND
Published: July 2006

A cardiac stimulator is described which combines the ease of operation required in clinical investigations, particularly endocavitary studies of cardiac arrhythmias, and the versatility needed in a research context. This instrument uses a microcomputer to control two independent opticully‐isolated Stimulation ports which can be addressed either independently or jointly to stimulate at two different sites. The main software module operates as a cascade of ten real time pulse generators with individually presettable parameters: amplitude, duration, period, initial delay, periodic and cyclic modifiers, triggering mode, etc, A simple interactive procedure allows the operator to define a stimulation protocol either by accessing the generator structure directly, or by calling any of five preprogrammed stimulation protocols. With this combination, the instrument can provide a large variety of pulse patterns. The operator can intervene at any lime during stimulation to change parameter values or modify the pulse pattern. Concurrently with stimulation, the instrument generates time‐codes to help relate car‐dine responses recorded on paper chart and magnetic tope, and reference them to specific events. The instrument can be readily expanded by the addition of parallel microprocessor modules; other real time tasks such as acquisition and processing of cardiac responses can thus be incorporated.
Permanent Programmable Pacemakers in the Management of Recurrent Tachycardias*
Authors: HYMAN ALBERT L.
Published: July 2006

Patient reports are presented to indicate the application of standard implanted programmable pacemakers with endocardial electrodes for long‐term overdrive suppression of recurrent ventricular tachycardia, and their adaptability to non‐invasively induced bursts of rapid ventricular pacing to cardioverl that arrhythmia. In carefully preselected patients with bradycardia‐tachycardia syndrome, this type of programmable pacemaker may also be used to convert paroxysmal supraventricular tachycardia by short bursts of rapid ventricular pacing. In addition, the advantage of non‐invasively instituting overdrive suppression with programmable pacemakers to control recurrent ventricular tachycardia appearing in patients being chronically paced for complete heart block is illustrated.
The Porous Endocardial Electrode
Authors: AMUNDSON DAVID C. , MCARTHUR WILLIAM , MOSHARRAFA MOSTAFA
Published: July 2006

AMUNDSON, D.C., McARTHUR, W., AND MOSHARRAFA, M.: The porous endocardial electrode. The permanent endocardial electrode has exhibited the problems of dislodgement, excessive threshold rises and Joss of sensing. These failure modes are addressed with a new electrode incorporating a porous body of Pt‐Ir fibers with a fiber diameter of 20 μm and an overall density of 10%. Porous electrodes have the advantages of utilizing the electrode interior both for tissue ingrowth to improve anchoring and for electrolyte penetration which improves fl wave amplitude and reduces polarization losses.

A series of 20 porous electrodes was compared with 17 solid electrodes of similar dimension. Electrodes were implanted in dogs in the apex of the right ventricle, and were subsequently followed up to 210 days. Comparison of the electrode data revealed that the porous electrodes had a 40% reduction in chronic voltage thresholds and had an overall dislodgement rote of 10%, compared to 53% for (he solid electrodes. Histological examination revealed tissue ingrowths throughout the electrode interior and a fibrotic capsule about half (he thickness of the solid electrodes. R wave stability was enhanced with the porous electrode due to improved anchoring, reduction in slew rate changes and less R wave attenuation.

Assuming results are translatable to humans, the porous elctrode will provide a greater pacing safety margin when used with a standard demand pacemaker, or improved longevity with the same safety margin as solid electrodes if used with a programmable pacemaker. The incidence of dislodgement and sensing failure will also be diminished with the porous electrode. (PACE, Volume 2, January‐February, 1.979)
Chest Thump and Ventricular Tachycardia
Authors: MORGERA T. , BALDI N. , CHERSEVANI D. , MEDUGNO G. , CAMERINI F.
Published: July 2006

Chest thump is a simple method of trrciimunt of some paroxysmal arrhythmias. Its therapeutic efficacy, electrophysiological bases and clinical utility have been studied in 17 patients during 45 episodes of ventricular tachycardia (VT). Thumping the precor‐dium interrupted the VT in 22 episodes. Three types of interruption of VT huvr been observed: (1) In 15 episodes, single ventricular premature beats induced by the Mow, occurring randomly in the cycle, stopped the arrhylhmia; (2) In episodes, a run of premature beats, induced by a rapid succession of blows, interrupted the tachycardia; (3) In 2 episodes, chest thump caused a short period of asystole followed by sinus rhythm. Chest thump is an antiarrhythmic treatment of definite clinical utility. The complications are rare, although (here is a possibility of ventricular fibrillation. Therefore, it should be performed only under careful supervision.
“Runaway” in a Modern Generation Pacemaker
Authors: ODABASHIAN H.C. , BROWN D.F.
Published: July 2006

Life‐threatening episodes of ventricular tachycardia were documented in a patient with an implanted Omni‐Stanicor pacemaker due to episodic pacemaker runaway. The unit generated impulses at rates varying from 73 to 500 per minute. Ventricular capture at high rates was variable, but frequently resulted in heart rates in excess of 200 per minute. These episodes were associated with loss of consciousness secondary to inadequate cardiac output. Although the pacemaker could be inactivated by reprogramming its output to 2 mA, and suppressed by chest wall stimulation with an external pulse generator, no spontaneous rhythm resulted during these maneuvers. Urgent removal of the battery at the bedside and immediate resumption of pacing with an external generator was required to resolve the problem. Although runaway is infrequent with current generation pacemakers, it should be considered in addition to the more common causes of pacemaker malfunction in the patient with appropriate symptoms.
Temporary Pacemaker Treatment in Open Heart Surgery: Variation in Myocardial Threshold, Tissue and Interface Impedances in Man*
Authors: OHM OLE‐JÖRGEN , MÖRKRID LARS , SKAGSETH ERLING
Published: July 2006

Mymcardial threshold and impedance of adequately insulated multicore metal electrodes (lengths 11 and 12) were investigated in 28 patients undergoing open heart surgery. Increase in current threshold from the pre‐ to postoperative period was: 607 ± 102% (mean ± SEM) with a constant‐current pulse generator and 885 ± 129% with a constant‐voltage pulse generator. Tissue impedance (RT= initial impedance) calculated as voltage/current ratio 90 μs into the pulse changed from 564 ± 34Ω before surgery to a minimum of 134 ± 7Ω. Thereafter, there was a gradual increase in RT to 162 ± 9Ω the day of electrode removal. In 25 of 28 patients the minimum values were reached the third to eighth postoperative day. Electrode/tissue interface impedances—Faraday resistance (RF) and Helm‐holtz capacity (CH)—were calculated from regression analysis of loaded and unloaded electrograms using the method of least squares. The RF showed a fall from 14.7 ± 1.4 K Ω to 5.2 ± 0.3 KΩ, and the CH (20–40 Hz) rose from 6.0 ± 0.9 μF to 15.5 ± 0.8 μF preoperatively to the day of minimum tissue impedance. There were no further changes until the day of electrode removal. A significant positive correlation was found between CH (p < 0.002), current threshold (p < 0.005) and equivalent electrode length [lequ= 11± 12/ (11+12)]. The electrode signal source impedance calculated from RT. HF and CH was of a magnitude not likely to contribute to demand failures. The low postoperative electrode impedance resulted in excessive load on the constant‐voltage generator (condenser discharge type), rendering stimulation of the heart with reasonable current values impossible.
Long‐Term Results of Permanent Atrioventricular Sequential Demand Pacing*
Authors: LÉVY SAMUEL , GÉRARD RAYMOND , JAUSSERAN JEAN‐MICHEL , BOYER CHRISTIAN , CLÉMENTY JACQUES , BAUDET EUGÈNE , BRICAUD HENRI
Published: July 2006

Pervenous atrioventricular sequential demand pacemakers (AVSDPs) were implanted in 18 patients using an atrial electrode positioned in the right atrial appendage and a ventricular electrode positioned at the apex of the right ventricle. The indications included 13 patients with the sick sinus syndrome (72%). five of whom had the tachycardia‐bradycardia syndrome, three with paroxysmal supraventricular tachycardia, one with cardiomyopathy and one with carolid sinus syncope. The follow‐up ranged from 6 to 38 months, with a mean of 19.4 months (a total of 350 pacing months). Seventeen patients (94%) are asymptomatic. One patient had persistent episodes of paroxysmal supraventricular tachycardia. In the remaining patients with tachyarrhythmia, pacing alone (three patients) or in combination with antiarrhythmic drugs (four patients) controlled the tachyarrhythmia. There was one displacement of the atrial electrode (5.5%). Extrusion of the pacer occurred in three patients. It is concluded from this experience that AV sequential pacing is an effective technique and may be useful in patients with sick sinus syndrome, in patients with tachyarrhythmia and/or patients with poor myo‐cardial function. However, continued research is needed to prolong battery life and to reduce the size of the pacemaker.
Ventricular Pacing from the Middle Cardiac Vein Mimicking Supraventricular Morphology
Authors: WAXMAN HARVEY L. , LAZZARA RALPH , CASTELLANOS AGUSTIN , EL‐SHERIF NABIL
Published: July 2006

A cose is described in which ventricular pacing from the middle cardiac vein produced an electrocardiographic pattern which mimicked the morphology of the normally conducted beats. The possible etiologies of this unusual phenomenon and its implications concerning the functional anatomy of the normal conduction system in the human heart are discussed.
The Interdependence Between Electrogram, Total Electrode Impedance and Pacemaker Input Impedance Necessary to Obtain Adequate Functioning of Demand Pacemakers
Authors: OHM OLE‐JÖRGEN
Published: July 2006

Electrogram maximum derivatives (DMAX, SMAX) and electro‐gram amplitudes (AMAX, UMAX) (Figure 2), were studied in 71 cases during permanent pacemaker treatment. During the acute phase, (at first implantation), 29 patients were studied, and during the chronic phase, (at pulse generator replacement), 42 patients were studied. Of these patients, 27 (acute phase) and 36 (chronic phase) were studied for tissue impedance (Ry) and interface impedance (Faraday resistance Rp and Helmholtz capacitych)‐ DMAX and SMAX changed from 3.47 ± 0.33 V/s (mean ± SEM) to 2.48 ± 0.23 V/s and 1.93 ± 0.20 V/s to 1.32 ±0.12 V/s; p < 0.02; p < 0.01. AMAX and UMAX remained nearly unchanged from acute to chronic phase. A paired comparison in 13 patients showed almost identical results.

Electrograms recorded in patients with bundle branch block showed no statistical difference in DMAX, SMAX, AMAX, and UMAX compared with electrograms recorded in patients with QRS‐complexes of normal duration.

No correlation was found between rise in myocardial threshold and fall in DMAX and SMAX from acute to chronic phase; p > O.8, p > 0.5.

Patients with coronary heart disease were found to have significantly higher AMAX than patients classified as having rhythm disturbances of primary cause; p < 0.01. Extremely low values of amplitudes and maximum derivatives were found in some patients with myocardial infarctions and cardiomyopathies. No difference existed in DMAX, SMAX, AMAX, and UMAX recorded from electrodes with a 8 mm2area compared with a 12 mm2area (p > 0.5).

rtwas statistically significantly higher on the smaller compared with the larger surface electrodes (p < 0.005). There was a slight but not statistically significant fall inrtfrom acute to chronic phase (p > 0.2). Rp ranged from 2.0–94.6 Kohms. There was no statistically significant differences between the 8 mm2compared with the 12 mm2electrodes (p > 0.2).chvaried between 0.7 and 37.0 microfarads, with significantly lower values for the smallest electrodes (p < 0.05), In patients with electro‐grams of borderline amplitudes and maximum derivatives for being sensed, the lowchfound with the small tip electrodes, will give a higher risk of demand failure if the input impedance in the sensing circuit of a demand pacemaker is too low.
The Frequency of New Permanent Pacemaker Implantations in 1975, 1980 and 1990 A Model Study Taking into Account the Dependence of Age and Sex
Authors: EDHAG OLOF , LEKHOLM ANDERS
Published: July 2006

Statistics of the number of new, permanent pacemaker systems per year have been obtained for various countries since the end of the 1960's. These figures have been expressed mostly as the number of new paced patients per million inhabitants. There is a progressive increase in the need of a pacemaker with increasing age. Demographic data show considerable differences in the number of elderly in the various countries. More pacemakers have been implanted in males than in females, The predicted number of new permanent pacemaker systems in 1960 and 1990 has been calculated for eleven countries and has been estimated to be 200 per million inhabitants of the total population (age and sex distributions in the populations have been taken into account). Considerable differences appear.
A Semi‐Automatic Device for Pacemaker Function Analysis
Authors: BEHAR S. , FISCHLER H. , FELDMAN S. , NEUFELD H.N.
Published: July 2006

An external semi‐automatic Pacemaker Function Analyzer (PFA) has been designed for routine examination (screening) of ambulatory‐paced patients in general medical practice. The evaluation of the pacemaker (PM) function is based on recognition, decoding, and measurement of the occurrence of QRS complexes and pacing artifacts, and on logic processing of the decoded data. In this way, the state of the batteries and the integrity of the electronic circuitry and the electrodes can be determined. Other PFA applications concern supervision of hospitalized patients by interfacing the analyzer with the monitoring system of a Coronary Care Unit (CCU) transtelephone checking, and adaptation for use in specialized pacemaker clinics. The performance of the PFA was checked on 92 ambulatory patients. The PFA system recognized all but 0.29% of the QRS complexes and 0.21 % of the pacing artifacts. Thirty‐two of these patients were tested simultaneously by the PFA and the pacemaker clinic physician, both arriving at the same results. Twelve hospitalized patients were monitored in the CCU, after permanent PM implantation, for an average of 4 hours per patient. Although the PFA indicated 5% false‐negative alarms for the hospitalized patients, it should be stressed that every true PM failure was promptly detected. It is anticipated that routine use of the PFA for management of paced patients will reduce the expenses incurred by frequent visits, as well as simplify the follow‐up and surveillance of ambulatory and hospitalized patients, thereby facilitating the work of the medical staff.
A Search for Modulation in Intermittent Ventricular Parasystole
Authors: CASTELLANOS AGUSTIN , ALATRISTE VICTOR M. , SUNG RUEY J. , SHEPS DAVID S. , MYERBURG ROBERT J.
Published: July 2006

As recently described by Moe et al., parasystolic modulation implies that the ectopic cycle length of a parasystolic focus can be increased or decreased by electrical influences transmitted across the zone of protection. A search for this phenomenon was made in nine patients with intermittent ventricular parasystole resulting from protection only during specific portions of the cycle. All nine patients had a period of relatively early protection affecting the initial 55–67% of the cycle preceding a period of resetting during which the parasystolic focus was discharged and fully recycled. In addition, two patients had a period of relatively late parasystolic protection. Pseudo‐resetting (apparent resetting in the surface leads without interruption of activity within the parasystolic focus itself), seen throughout the entire period of late protection in these two patients, and during the relatively refractory period in one patient, was identified because the R waves causing apparent resetting were encompassed by parasystolic‐to‐parasystolic intervals equalling twice the ectopic cycle length. Our findings indicate that parasystolic modulation did not occur in the type of intermittent ventricular parasystole included in this study. That is, the parasystolic focus was either not affected (not modulated) during specific (early or late) portions of the cycle, or normally reset (discharged and fully recycled, but neither depressed, nor enhanced) in other portions of (he cycle. This study does not exclude the occurrence of modulation in other types of parasystole, nor in some automatic nonparasystolic rhythms.
Suppression of a Demand Pacemaker in the Presence of Redundant Transvenous Right Ventricular Leads
Authors: TYERS G. FRANK O. , LARRIEU ALBERTO J. , NISHIMURA AKIRA , WILLIAMS EDWARD H. , KURUSZ MARK , BROWNLEE ROBERT. R.
Published: July 2006

A ventricular inhibited demand cardiac pacemaker was inhibited in the presence of intimate contact between the active temporary bipolar electrode ring and a retained inactive permanent bipolar electrode tip. Electromagnetic interference effects, lack of insulation, lead breaks, and loose connections were all ruled out as the cause of pacemaker suppression.
Possible Risks of General Anesthesia in Patients with Intraventricular Conduction Disturbances
Authors: SANTINI M. , CARRARA P. , BENHAR M. , PIOVANO G. , ROCCHI M. , Di MASCOLO R. , MASINI V.
Published: July 2006

In order to assess the risk of complete AV bloek in patients, with intraventricular conduction disturbances who undergo general anesthesia, 20 patients with various conduction defects (7 LBBB, 1 RBBB and 1st degree AV block, 1 incomplete RBBB, 9 RBBB+LAH and 2 RBBB+LPH) were studied by means of His bundle recording and corrected sinus node recovery time (CSNRT) before and after the subministration of thiopental (0.2 g. I.V.), succinylcholine (1 mg/kg I.V.), Eluothane (l%) and Ethrane (1.6%). Nineteen patients displayed signs of dizziness or syncope; both the sinus rate and the CSNRT, did not undergo significant variations. A slight and not significant variation of intranodal conduction during sinus rhythm was observed after Fluothane administration (AH was prolonged by 8%). A less evident negative dromotropic action of thiopental and Ethrane was only revealed by atrial pacing. No significant variations were demonstrated in His‐ventricular conduction after administration of the various drugs. The maximum average increase (1.5%) of the H‐V interval was observed after administration of succinylcholine. Acute AV block distal to the His bundle appeared in three patients after succinylcholine administration.
A Mini‐System for Storage, Retrieval and Management of Pacemaker Data
Authors: SALVADOR‐MAZENQ MICHÈLE , CANDELON BERNARD , GRAULLE ANDRÉ , PUEL PIERRE
Published: July 2006

Information processing is becoming a necessity for the management and the analysis of data at Cardiac Electrostimulation Centers, particularly since pacemaker implantation is becoming more frequent and the material more diversified. The mini system described allows retrieving of simple data and allows a real time acquisition of spike parameters by means of an electronic coupling unit with an impulse analyser. Its simplicity, availability and low cost are desirable qualities needed for the proper functioning of a Pacemaker Implantation Center.
Mannal Extraction of a Permanent Pacemaker: An Attempted Suicide
Authors: ROSENTHAL ROBERT , CRISAFI BARTEL R. , COOMARASWAMY RAMA P.
Published: July 2006

An unusual case of a patient‐related pacemaker malfunction is presented. In a suicide attempt the patient manually extracted a subcutaneously implanted permanent pacemaker. This shocking example of pacemaker manipulation by a patient raises the question of the need for more routine use of protected sites for pacemaker implantation.
Preliminary Studies with an Implantable Multimodal A‐V Pacemaker for Reciprocating Atrioventricular Tachycardias
Authors: CASTELLANOS AGUSTIN , WAXMAN HARVEY L. , MOLEIRO FEDERICO , BERKOVITS BAROUH V. , SUNG RUEY J.
Published: July 2006

The efficacy of a recently developed programmable implantable pacemaker which can be used in the management of supraventricular tachycardias (with, or without, associated brady‐arrhythmias) was evaluated in the cardiovascular laboratory and at the bedside in the coronary care unit. Although this pacemaker functions primarily in a DVJ‐DVO mode, it was also made (iatrogenically) to operate in a DOO mode. The study was performed in six patients with reciprocating atrioventricular tachycardias (four of the long P‐R short R‐P type and two of the short P‐R—long R‐P type). Both DVJ‐DVO and DOO pacing abolished all episodes of tachycardia in five of the patients. However, DOO pacing was also capable of initiating episodes of tachycardia in two of the six patients. The events observed in two of the patients raise the possibility that (reversed) ventriculoatrial sequential pacing may be required in some tachycardias of the short P‐R—long R‐P type. This preliminary study suggests that programmability of pacing modes, rates, and intervals is a desirable feature that pacemakers used to manage drug‐resistant tachycardias should have
His Bundle in Electrocardiographic Semantics of AV Block. Anatomoclinical Considerations
Authors: ROSSI LINO
Published: July 2006

The A V conducting system was examined histologically in 13 selected human hearts (7 control and 6 A V block specimens), focusing attention upon normal His bundle (HB) structure, and upon the histopathologic basis of intrahisian block, with supraventricular QRS configuration. HB revealed a poor morphologic identity, often failing to represent the “undivided stem” of the AV pathway, either due to an early partition into separate longitudinal fascicles, or to varied types and sites of bifurcation, without any definite boundary between nonbranching and branching portions. Split His potentials, the distal component of which has been suggested as arising in the proximal bundle branch system, has been found in a case free of HB histologic abnormality. Supra ventricular QRS configuration in escape rhythm was observed in two cases of AV block, not withstanding destruction of the entire His bifurcation, and in experimental bilateral bundle branch block. Pertinent explanations have been suggested. The overall semantic value and usefulness of the current HB nomenclature do not seem to imply, as yet, a precise and constant anatomoclinical correlation.