bluuebunny/crossref_metadata_2025 huggingface dataset:
Proteomic analysis of the effects and interactions of sleep deprivation and aging in mouse cerebral cortex
Authors: Pawlyk Aaron C. , Ferber Megan , Shah Aanal , Pack Allan I. , Naidoo Nirinjini
Published: October 2007

The cellular and molecular processes that underlie the drives and functions of sleep have been the topic of many studies in the last few decades. Discovery‐based techniques, such as cDNA microarrays, have increasingly been utilized in conjunction with sleep deprivation paradigms to examine the molecular mechanisms and functions of sleep. These studies have helped to validate and expand existing hypotheses, such as those on the roles of sleep in synaptic plasticity and in energy metabolism. The mechanisms underlying the highly prevalent changes in sleep architecture with age are not known, but likely reflect fundamental changes in the molecular basis of circadian timing and sleep homeostatic processes. We decided to explore the effects and interactions of sleep deprivation and aging utilizing the proteomic technique of difference in gel electrophoresis (DIGE). DIGE, which utilizes cyanine dye labeling of samples, allows for the comparison of multiple experimental groups within and across gels. In this study, we compared cerebral cortex tissue from young (2.5 months) and old (24 months) mice that had been sleep deprived for 6 h to tissue from undisturbed young and old control animals. Following DIGE, automatic image matching and spot identification, and statistical analysis, 43 unique proteins were identified. The proteins were grouped into seven functional classes based on published characteristics: cell signaling, cytoskeletal, energy metabolism, exocytosis, heat shock proteins, mRNA processing/trafficking, and serum proteins. The identity and characteristics of these proteins relevant to sleep and aging are discussed.
Isolation and characterization of microsatellite loci in the beaver (Castor canadensis)
Authors: CRAWFORD J. , LIU Z. , NELSON T. , NIELSEN C. , BLOOMQUIST C.
Published: October 2007

We have isolated and characterized 10 microsatellite loci in the beaver (Castor canadensis). Sixty individuals from southern and central Illinois were screened at each locus. All loci exhibited moderate levels of polymorphism, ranging from five to 13 alleles per locus with average heterozygosity ranging from 0.317 to 0.867. Locus Cca5 deviated significantly from HWE (P < 0.001). The locus pair Cca4/Cca5 was shown to be in linkage disequilibrium in southern Illinois, but not in the central Illinois population. The remaining eight loci will be useful in investigations of mating and kinship patterns in beaver populations in Illinois.
Indigenous, Colonist, and Government Impacts on Nicaragua's Bosawas Reserve
Authors: STOCKS ANTHONY , McMAHAN BENJAMIN , TABER PETER
Published: October 2007

Abstract:  We studied the impacts of colonists, two groups of indigenous residents (Miskitu and Mayangna), and management by the Nicaraguan Ministry of Environment and Natural Resources (MARENA) on the forest of the Bosawas International Biosphere Reserve. Indigenous people and colonists subsist on the natural resources of the reserve, and MARENA is responsible for protecting the area from colonization and illicit exploitation. Using geostatistical procedures and Landsat images at three different time periods, we compared per capita deforestation and boundary stabilization in areas with colonists and areas with indigenous peoples. We also examined whether the Mayangna deforested less than the Miskitu and whether the Nicaraguan government has effectively defended the Bosawas boundary against the advance of the agricultural frontier. In addition, we analyzed the current distribution of land uses within the reserve and its contiguous indigenous areas with a supervised classification of current land cover. Indigenous demarcations protected the forest successfully, whereas the Bosawas boundary itself did not inhibit colonization and consequent deforestation. Indigenous farmers deforested significantly less per capita than colonists, and the two indigenous groups in Bosawas did not differ significantly in their effects on the forest. Our results show that indigenous common‐property institutions and indigenous defense of homeland have been powerful factors in protecting the forests of Bosawas and that the difficult evolution of a nested cross‐scale governance system in Bosawas—under pressure from indigenous peoples—is probably the key to the forest's survival thus far.
Effectiveness of Surrogate Taxa in the Design of Coral Reef Reserve Systems in the Indo‐Pacific
Authors: BEGER MARIA , McKENNA SHEILA A. , POSSINGHAM HUGH P
Published: October 2007

Abstract:  Implementing systematically designed reserve systems is crucial to slowing the global decline of coral reef health and diversity. Yet, the paucity of spatial data for most coral reef taxa often requires conservation planners to design reserve systems based only on a subset of taxonomic groups as surrogates for all other taxa. In terrestrial systems the validity of surrogates for reserve design is established by testing for cross‐taxon congruence (similarities in spatial patterns of species richness), but this concept has rarely been examined in the marine environment. We tested the suitability of taxa as conservation representation surrogates of coral reef species richness across the Indo‐Pacific, based on species lists of fishes, corals, and mollusks from 167 sites. First, we tested the relevance of cross‐taxon congruence patterns to predict these surrogacy patterns. We determined congruence between taxonomic groups by conducting a correlation analysis of dissimilarity values between pairs of sites. We then evaluated how well each taxonomic group represented the other groups in a marine reserve system selected by a greedy reserve‐selection algorithm relative to reserve systems selected by chance. No taxonomic group we examined was a reliable surrogate for the other groups such that site selection based on that group always represented other taxa significantly better than random selection of sites. Sites selected based on hard corals represented the other taxonomic groups in a reserve system worse than randomly selected sites. Although we found high cross‐taxon congruence between fishes and corals and between corals and mollusks, for some regions cross‐taxon congruence was not always a reliable indicator of the ability of one taxonomic group to efficiently represent another in a reserve system. We concluded that in Indo‐Pacific coral reef ecosystems one can only be sure that a target taxon is efficiently represented in a reserve system when data on that taxon are used to select a reserve system.
Disturbance‐Mediated Mammal Persistence and Abundance‐Area Relationships in Amazonian Forest Fragments
Authors: MICHALSKI FERNANDA , PERES CARLOS A.
Published: October 2007

Abstract: Few researchers have investigated the synergistic effects of tropical forest fragmentation and disturbance on species persistence and abundance. We examined effects of both forest‐patch metrics and forest disturbance in determining richness and abundance of midsized to large‐bodied mammal species in a highly fragmented Amazonian forest landscape. Twenty‐one forest fragments, ranging from 2 to 14,480 ha, and two continuous forest sites were sampled based on sightings, tracks, line‐transect censuses, armadillo burrow censuses, and camera trapping. Patch occupancy of 37 species recorded ranged from 4% to all forest sites surveyed. Forest fragment size was the strongest predictor of species persistence, explaining 90% of the variation in species richness. Information‐theoretic analysis confirmed that fragment area was the most important explanatory variable for the overall species richness and abundance of mammal species, followed by surface fires, which affected the abundance of seven species. Large mammal species were typically absent from fragments <100 ha, whereas some ubiquitous species were favored by fragmentation, exhibiting hyperabundance in small patches. Our findings highlight the importance of large (>10,000 ha), relatively undisturbed forest patches to maximize persistence and maintain baseline abundances of Neotropical forest mammal species.
Range Size and Extinction Risk in Forest Birds
Authors: HARRIS GRANT , PIMM STUART L.
Published: October 2007

Abstract: Small geographical range size is the single best predictor of threat of extinction in terrestrial species. Knowing how small a species' range has to be before authorities consider it threatened with extinction would allow prediction of a species' risk from continued deforestation and warming climates and provide a baseline for conservation and management strategies aspiring to mitigate these threats. To determine the threshold at which forest‐dependent bird species become threatened with extinction, we compared the range sizes of threatened and nonthreatened species. In doing so, we present a simple, repeatable, and practical protocol to quantify range size. We started with species' ranges published in field guides or comparable sources. We then trimmed these ranges, that is, we included only those parts of the ranges that met the species' requirements of elevation and types of forest preferred. Finally, we further trimmed the ranges to the amount of forest cover that remains. This protocol generated an estimate of the remaining suitable range for each species. We compared these range estimates with those from the World Conservation Union Red List. We used the smaller of the two estimates to determine the threshold, 11,000 km2, below which birds should be considered threatened. Species considered threatened that have larger ranges than this qualified under other (nonspatial) red list criteria. We identified a suite of species (18) that have not yet qualified as threatened but that have perilously small ranges—about 11% of the nonthreatened birds we analyzed. These birds are likely at risk of extinction and reevaluation of their status is urgently needed.
The NR1 N‐Methyl‐d‐Aspartate Subunit and Brain‐derived Neurotrophic Factor in Temporal Lobe Epilepsy Hippocampus: A Comparison of Patients with and without Coexisting Psychiatric Symptoms
Authors: Toro Carla Tatiana , Hallak Jaime E. , Dunham Jason S. , Leite João P. , Sakamoto Américo C. , Guarnieri Ricardo , Fong Vivian , Deakin John F. W.
Published: October 2007

Summary

Purpose: The glutamate N‐methyl‐d‐aspartate (NMDA) receptor and the neurotrophin brain‐derived neurotrophic factor have been implicated in the pathophysiology of schizophrenia and depression. Since these psychiatric disorders are common in temporal lobe epilepsy (TLE), a comparison of TLE patients with and without coexisting psychiatric symptoms may be useful to unravel pathophysiologic mechanisms for psychosis or depression.

Methods: We used immunoautoradiography to assess the NR1 NMDA receptor subunit and brain‐derived neurotrophic factor in resected TLE hippocampus.

Results: No changes relative to comparison controls were found for TLE patients with schizophrenia‐like psychosis or depression. Increased NR1 was found in the dentate molecular layer in the dysphoria group and unmedicated depressed patients.

Conclusions: An increase in NR1 protein in the dentate molecular layer suggests an upregulation of NMDA receptors in granule cells in TLE patients with dysphoria and depression. This finding is compatible with the theory that increased NMDA receptor function is involved in the pathogenesis of depression and that antidepressants may act by opposing this mechanism.
A Prospective Study of the Modified Atkins Diet for Intractable Epilepsy in Adults
Authors: Kossoff Eric H. , Rowley Hannah , Sinha Saurabh R. , Vining Eileen P. G.
Published: October 2007

Summary

Purpose: The ketogenic diet is not typically offered to adults with epilepsy due to the significant lifestyle alterations needed for its use. The modified Atkins diet has been recently demonstrated to be therapeutic for children without the need for an admission, fasting period, weighing of foods, or fluid, calorie, and protein restriction.

Methods: A prospective, open‐label study was performed of adults over 18 years of age, having at least weekly seizures and prior use of at least two anticonvulsants. Carbohydrates were initially restricted to 15 g/day, fats were encouraged, and fluids, protein, and calories were allowed ad lib.

Results: Thirty patients, with age ranging from 18 to 53 years, were enrolled. Using an intent‐to‐treat analysis, 47% had a >50% seizure reduction after 1 and 3 months on the diet; 33% after 6 months. In those with seizure reduction, the median time to improvement was 2 weeks (range: 1–8 weeks). The mean weight loss was 6.8 kg, p < 0.001. Body‐mass index (BMI) decrease correlated with efficacy at 3 months, p = 0.03. Ten subjects (30%) discontinued the diet prior to 3 months. Side effects included increased cholesterol (mean 187 to 201 mg/dL), blood urea nitrogen (BUN; 13 to 16 mg/dL), and urine calcium to creatinine ratio (0.14 to 0.19).

Conclusions: A modified Atkins diet appears to demonstrate preliminary efficacy for adults with intractable epilepsy, especially in those who lost weight. Considering the rapid response in those who improved, but somewhat high discontinuation rate, a 2‐month trial period may be adequate to assess for efficacy.
Alignment of P Waves for Signal Averaging
Authors: SCOTT WILLIAM A. , DONNERSTEIN RICHARD L.
Published: October 2007

SCOTT, W.A., ET AL.: Alignment of P Waves for Signal Averaging. Signal averaged atrial activity recorded from the body surface is finding increased use in assessing atrial arrhythmias. The process of signal averaging is critically dependent upon precise alignment of the waveform of interest. The alignment accuracy of wide (0.01–300 Hz) and narrow (10–300 Hz) bandpass filtered P waves recorded from the body surface were compared to atrial electrograms recorded from temporary pacing wires. The locations of the filtered P waves relative to the atrial electrogram were calculated beat‐by‐beat for 100 beats in 15 patients aged 1 month to 71 years. The standard deviation of the alignment error for the wide filtered surface P wave averaged 1.7 ± 0.8 msec and for the narrow filtered P waves was 0.8 ± 0.4 ms. These results demonstrate that high pass filtering will improve alignment accuracy, and therefore, improve frequency resolution for the analysis of signal averaged P waves.
Ventricular Pacing from the Atrial Channel of a DDD Pacemaker: A Consequence of Pacemaker Twiddling?
Authors: ANDERSON MARK H. , NATHAN ANTHONY W.
Published: October 2007

ANDERSON, M.H., ET AL.: Ventricular Pacing from the Atrial Channel of a DDD Pacemaker: A Consequence of Pacemaker Twiddling? The breakdown of pacemaker lead insulation under conditions of mechanical stress leading to failure of pacing is well recognized. We present a case where adjacent breakdown of insulation in two unipolar pacing leads resulted in inappropriate ventricular pacing. Replacement of the leads rectified the problem. [PACE, Vol. 13, December, Part I 1990)
Return Ventricular Rhythm: New Mechanism for Tachyarrhythmia
Authors: PIMENTA JOÃO , PEREIRA MARIA HELENA B.
Published: October 2007

PIMENTA, J., ET AL.: Return Ventricular Rhythm: New Mechanism for Tachyarrhythmia. A case study is presented in which the electrocardiographic patterns during tachycardia showed ventricular premature depolarizations with retrograde conduction to the atria probably using a left‐sided anomalous pathway and reentry to the ventricles with normal ventricular activation and duplication of the heart rate. This type of tachycardia is being labeled “return ventricular rhythm” and, as far as it is known, this is the first description of its mechanism.
Directional Variability of Stimulation Threshold Measurements in Isolated Guinea Pig Cardiomyocytes: Relationship with Orthogonal Sequential Defibrillating Pulses
Authors: BARDOU ALAIN L. , CHESNAIS JEAN‐MICHEL , BIRKUI PIERRE J. , GOVAERE MARIE‐CLAUDE , AUGER PIERRE M. , EUW DOMINIQUE VON , DEGONDE JEAN
Published: October 2007

BARDOU A.L., ET AL.: Directional Variability of Stimulation Threshold Measurements in Isolated Guinea Pig Cardiomyocytes: Relationship with Orthogonal Sequential Defibrillating Pulses. Reports on delivery of separated orthogonal pulses markedly improving cardiac defibrillation have suggested that the stimulation threshold of heart fibers varies in accordance with their orientation within the electric field. The present work was aimed at investigating the directional variability of stimulation thresholds in isolated guinea pig cardiomyocytes. This variability was measured in 48 single myocytes by rotating each one through a theta (θ) angle between two‐fixed parallel electrodes 1.1 cm apart, thus making θ vary between the electric field and the myocyte axis. For θ= 0°, the mean longitudinal current stimulation threshold was 16.92 ± 4.20 mA (n = 48). When θ was increased by increments of 10° up to 90°, the stimulation threshold increased in an exponential way. For θ= 90°, the mean transverse stimulation threshold was 63.23 ± 13.30 mA. These results clearly demonstrate the dependence of isolated cardiomyocyte stimulation thresholds on their orientation within the electric field and may account for the improved efficacy of defibrillation previously observed after delivery of orthogonal pulses.
Initial Clinical Experience with Rate Adaptive Cardiac Pacing Using Two Sensors Simultaneously
Authors: LANDMAN M.A.J. , SENDEN P.J. , ROOIJEN H. VAN , HEMEL N.M. VAN
Published: October 2007

LANDMAN, M.A.J., ET AL.: Initial Clinical Experience with Rate Adaptive Cardiac Pacing Using Two Sensors Simultaneously. In the rate adaptive pacemakers, all presently available sensors show one or more drawbacks. Combining two sensors in a single pacemaker, we tried to optimize its rate responsive characteristics. In this study, we present the rate adaptive behavior of a two sensor pacemaker system, using both QT interval and activity sensing. In addition, we compared the rate response with that of each sensor alone. Nine patients with an implanted QT interval sensing pacemaker, and an externally attached activity sensing pacemaker performed three exercise stress tests on treadmill. The QT interval, measured by the implanted pacemaker, and the activity level, were transmitted to an external computer. This computer contained the two sensor rate adaptive algorithm, and reprogrammed the implanted pacemaker on beat‐to‐beat basis. Conclusion: In the two sensor mode the rate increases immediately at the onset of exercise, caused by the prompt response of the activity sensor. Further rate increase is driven by the QT interval sensor and therefore proportional to the level of exercise. Furthermore, the rate decay during the recovery phase is more physiological.
Complex Rhythms Resulting From Overdrive Suppression in Electrically Stimulated Heart Cell Aggregates
Authors: WANZHEN ZENG , MORISSETTE JOSÉE , BROCHU RICHARD , GLASS LEON , SHRIER ALVIN
Published: October 2007

WANZHEN, Z., ET AL.: Complex Rhythms Resulting From Overdrive Suppression in Electrically Stimulated Heart Cell Aggregates. Spontaneously beating embryonic chick heart cell aggregates were stimulated with current pulses delivered either as periodic trains, or at a fixed delay after each action potential. Following Stimulation at fixed rates faster than the intrinsic rate, there was a transient slowing of the spontaneous rhythm. This response, called overdrive suppression, can lead to a complex evolution of rhythms. During periodic stimulation there is a continuum of dropped beat patterns, and during fixed delay stimulation bursting activity appears. This study provides a conceptual basis for understanding analogous rhythms in the intact heart.
Automatic Adjustment of Pacing Parameters Based on Intracardiac Impedance Measurements
Authors: SCHALDACH MAX
Published: October 2007

SCHALDACH, M.: Automatic Adjustment of Pacing Parameters Based on Intracardiac Impedance Measurements.The selection of the parameters used for rate control is determined not only by technical feasibility, but also by patient considerations. Technical feasibility considerations include long‐term stability and reliability of the sensor, as well as susceptibility to interference. The patient considerations relate to the patient's physical state, including the various physiological and pathologic conditions. The rate response must be in proportion to circulatory demand. The specificity of the rate response is of particular importance for the patient with low cardiac reserve. The development of future pacemakers aims at providing additional patient benefits, with a reduction of the effort associated with initial parameter selection and patient follow‐up. This will be achieved by utilizing a better understanding of the integration of the control mechanisms for the entire cardiovascular system under physiological and pathological conditions. To support the development of the future pacemakers, we must utilize realistic multiparametric models of the cardiovascular system. These models will assist the evaluation of potential algorithms for integrating multisensor signals into a single pacing rate. The parameterization and validation of these models are important issues to be addressed. Intracardiac impedance measurements in conjunction with microprocessor controlled signal processing and improved lead technology provide a great variety of practical applications for physiological control of the pacing rate and the automatic adjustment of pacemaker parameters. The concepts of an “intelligent” pacemaker capable of automatic control in response to changes in the pacing requirements under a variety of physiological and clinical conditions are presented.
AV Delay and Exercise Stress Tests: Behavior in Normal Subjects
Authors: BARBIERI D. , PERCOCO G.F. , TOSELLI T. , GUARDIGLI G. , ANSANI L. , ANTONIOLI G.E.
Published: October 2007

BARBIERI, D., ET AL.: AV Delay and Exercise Stress Tests: Behavior in Normal Subjects. In normal subjects the atrioventricular (AV) conduction is accelerated during exertion. The relationship between heart rate and AV delay is usually described as “linear”. Looking at the increasing importance given to an appropriate AV synchrony in permanent dual chamber and P synchronous pacing we present the results of an investigation performed to study the correlation between AV conduction time and heart rate under stress conditions, and disclose some new aspects of this matter, which will possibly be useful for a further improvement of pacemaker technology.
Assistant Programming Software: A New Tool for an Improved Programming of Pacemakers
Authors: LASCAULT GILLES , NITZSCHÉ RÉMI , RITTER PHILIPPE , REMY MARTINE , LIMOUSIN MARCEL
Published: October 2007

LASCAULT, G., ET AL.: Assistant Programming Software: A New Tool for an Improved Programming of Pacemakers. Programming the new DDD pacemakers is becoming increasingly difficult. One must take into, account the pacemaker's complexity, the fact that some parameters are linked to others, and the clinical profile of the patient. This difficult problem will lead to the design of software to assist programming, which will help the implanting physicians in choosing adequate programmed settings adapted to the functioning of the device and to the physiology and pathology of the patient. These programming aides should meet certain basic requirements to make them safe, efficient, and easy to use. One such system designed by ELA Médical, “Programming Assistant” is herein described. The preliminary results of an initial study on the acceptance of this programming aide among physicians involved in cardiac pacing are given and discussed.
Left Atrial Size and Wall Motion in Patients with Permanent Ventricular and Atrial Pacing
Authors: KUBICA JACEK , STOLARCZYK LUKASZ , KRZYMINSKA ELZBIETA , KRASOWSKI ROBERT , RACZAK GRZEGORZ , LUBIŃSKI ANDRZEJ , STANKE ANDRZEJ , SWIATECKA GRAŻYNA
Published: October 2007

KUBICA, J., ET AL.: Left Atrial Size and Wall Motion in Patients with Permanent Ventricular and Atrial Pacing. It is well known that during permanent ventricular pacing atrial arrhythmias and embolic complications occur much more frequently in comparison to permanent atrial or sequential pacing. He‐modynamic disturbances caused by ventriculoatrial conduction (VAC) are thought to be responsible for those complications. The aim of this study was to compare the left atrial size and its wall motion in three groups of patients with sick sinus syndrome. Group 1: 58 patients with VVI pacing and VAC observed (22 males, 36 females, aged 31–86, mean 62.3). Group 2: 43 patients with primary AAI pacing (13 males, 30 females, aged 27–74, mean 57.8). Group 3: 13 patients with AAI or DDD replacing the primary VVI mode due to pacemaker syndrome and/or heart failure, all with VAC present during VVI pacing (7 males, 6 females, aged 26–80, mean 59.8). Two‐dimensional/M‐mode echocardiography was performed in all these patients. In group 1 mean diastolic as well as mean systolic atrial diameters were significantly greater (p < 0.005) and wall motion significantly smaller (p < 0.005) in comparison to the other groups. Left atrial wall motion amounted to only 7.4% of the mean diastolic diameter in this group. Mean left atrial diastolic and systolic diameters and wall motion in patients with pacemakers preserving atrioventricular synchrony (group 2 and group 3) were almost identical and wall motion amounted to about 22% of the diastolic diameter in both these groups. We conclude that ventriculoatrial conduction leads to significant enlargement of left atrium and to the atrial wall‐motion decrease. This predisposes to arrhythmias and embolic complications. Changes in atrial size and performance seem to be reversible with restoration of the physiological atrioventricular synchrony.
Usefulness of 1‐Hour and 24‐Hour Heart Rate Holter Inbuilt in New TX* Rate Adaptive Pacemakers
Authors: SERMASI SERGIO , MARCONI MARCC , MARZALONI MARIO
Published: October 2007

SERMASI S., ET AL.: Usefulness of 1‐Hour and 24‐Hour Heart Rate Holter Inbuilt in New TX* Rate Adaptive Pacemakers. The rate adaptive TX* pacemaker uses the evoked QT interval as an indicator of physiological demand. In order to obtain a rate adaptation close to physiological patterns we used in the past, in each patient, on the slope value and/or the T wave sensing window, controlling via exercise stress testing and Holter the results achieved. It was an expensive method, but the system produced effective rate responsive pacing. The new series of TX* pacemakers (Quintech 919 and Rhythmyx), beside the dynamic slope feature, are equipped with a 1‐hour heart rate Holter (HRH) that can be used during effort without the need for manually recording the heart rate. In this mode TX* pacemakers calculate the average heart rate over 20‐second periods and stores the values continuously for 1 hour. In addition, a 24‐hour HRH is available, which calculates the average heart rate over 7.5‐minute periods, showing heart rate trend during the last day prior to interrogation. Each HRH can be accessed by the programmer and printed out. Using four Quintech 919* and five Rhythmyx units, the inbuilt HRH proved its utility by making the heart rate adaptation checking procedure easier, faster, and more economic.
Evaluation of Rate‐Responsive Pacemakers by Transesophageal Holter Monitoring of Spontaneous Atrial Rate
Authors: BONGIORNI MARIA GRAZIA , SOLDATI EZIO , PAPERINI LUCA , POZZOLINI ANDREA , LEVORATO DIANORA , ARENA GIUSEPPE , PISTELLI PAOLO , QUIRINO GIANLUCA , BIAGINI ANDREA , CONTINI CARLO
Published: October 2007

BONGIORNI, M.G., ET AL.: Evaluation of Rate‐Responsive Pacemakers by Transesophageal Holter Monitoring of Spontaneous Atrial Rate. One of the most important problems in rate responsive (RR) pacing is the clinical experimental evaluation of the reliability of various sensors. In particular, it is difficult to test their sensitivity and specificity during daily activity of the patients. Atrial rate, when present and normal, is the most physiological marker of metabolic requirements, but sometimes it is impossible to analyze the P wave in ventricular paced rhythm during routinely performed tests (e.g., ergometric test and 24‐hour Holter monitoring). During various physical activities, we monitored atrial electrograms on an esophageal lead on the first channel of a standard Holter tape recorder; on the second channel a surface ECG lead was recorded. We selected 10 patients with high grade heart block and normal sinus node function paced in RR‐VVI mode. RR pacing was obtained using various sensors (body activity, blood temperature, spike‐T interval, minute ventilation). The good quality of recording allowed an easy evaluation of atrial and ventricular rates. In four cases an appropriate increase in heart rate was documented; sensitivity threshold and/or rate response slope were reprogrammed when indicated. The pacing rate of one patient did not parallel the atrial rate during walking only. In three cases, we observed a delay in the ventricular rate increase, with ventricular rate decreasing at peak exercise despite further atrial rate increase. In the last two patients, we observed inappropriate pacing response; pacing rate increased later and to a lower level than the atrial one. This new method is applied easily and appears reliable to evaluate the response of RR pacemakers to individual metabolic needs. Its applicability is, however, limited by the need for a normal sinus node function. In conclusion, transesophageal atrial rate recording is a useful tool for the clinical evaluation of RR pacemakers, and it can be proposed as a new method for testing new sensors.
The Six‐Minute Walk—An Adequate Exercise Test for Pacemaker Patients?
Authors: LANGENFELD HEINER , SCHNEIDER BETTINA , GRIMM WOLFRAM , BEER MARKUS , KNOCHE MICHAELA , RIEGGER GÜNTER , KOCHSIEK KURT
Published: October 2007

LANGENFELD, H., ET AL.: The Six‐Minute Walk—An Adequate Exercise Test for Pacemaker Patients? In many pacemaker patients bicycle and treadmill ergometry are not practicable. As an alternative, we performed a 6‐minute walk on a 20‐m corridor in 97 pacemaker patients, who were asked to walk as far as possible determining their speed by themselves. Results were compared with those of bicycle ergometry in 42 of these patients and with treadmill exercise of a group of 92 other pacemaker patients. In the 6‐minute walk, performance and maximal heart rate were slightly lower (49 ± 18 W; 96 ± 23 beats/min) than in bicycle (57 ± 16 W; 110 ± 26 beats/min) and treadmill ergometry (50 ± 37 W; 102 ± 35 beats/min). A good correlation was found between walking and bicycling (r = 0.74) and in subgroups of patients with different pacemaker indications. All patients preferred the walk to bicycle ergometry considering it to be more related to daily physical activity. In conclusion, a 6‐minute walk is a simple and physiological exercise test for nearly all pacemaker patients with good correlation to other types of exercise. It seems to be preferable to other tests because of its better acceptance and practicability.
C‐AMP and ANP Levels in VVI and DDD Pacing with Different AV Delays During Daily Activity and Exercise
Authors: THEODORAKIS GEORGE , KREMASTINOS DIMITRIOS , LIVANIS MANOLIS MARKIANOS EFTHIMIOS , ARCHONTAKIS CHRISTOS , KARAVOLIAS GEORGE , TOUTOUZAS PAVLOS
Published: October 2007

THEODORAKIS, G., ET AL.: C‐AMP and ANP Levels in VVI and DDD Pacing with Different AV Delays During Daily Activity and Exercise.Nine patients (three males) mean age 68 ± 8 years, having complete heart block, and paced in the DDD mode were examined in VVI and DDD pacing with 100 and 150 ms atrioventricular delays (AVD) during rest and exercise. Plasma atrial natriuretic peptide (ANP) and cyclic AMP (c‐AMP) were measured at rest and at peak exercise test. ANP plasma levels at rest were significantly higher in VVI pacing compared to 150 AVD (p < 0.03). On exercise, ANP release was statistically increased only in DDD with 150 ms AVD, while in WI it remained in high levels at exercise but no significant change was found (p:ns). c‐AMP during rest was unchanged in any pacing mode or AVD, but on exercise DDD pacing with short AVD (100 ms) released lower c‐AMP plasma levels, than at rest (p:ns). DDD pacing with long AVD (150 ms) during exercise produced statistically higher c‐AMP plasma levels (p < 0.05) than at rest. Also in VVI pacing the c‐AMP plasma levels were statistically higher than at rest (p < 0.02). Adrenergic activity seems to be lower during exercise in DDD pacing with shorter AVD (100 ms) than in DDD with 150 ms AVD or VVI pacing. No difference was found in c‐AMP plasma levels at rest. ANP release was also found to be lower at exercise in DDD pacing with short AVD (100 ms) than in DDD with 150 ms AVD. ANP plasma levels at rest were statistically higher in VVI pacing. (PACE, Vol. 13, December, Part II 1990)
Computerized Pacemaker Patient Analysis
Authors: BYRD CHARLES B. , HALLBERG BRYAN S. , BYRD CHARLES L.
Published: October 2007

BYRD, C.B., ET AL.: Computerized Pacemaker Patient Analysis. We have developed computer hardware and software that imports analog waveforms and other measured data from a patient into the PaceBase database system supported by any IBM PC/AT compatible. The programmable AID converter has the capacity to acquire the pacemaker artifact from the surface ECG leads. Analysis of the pacemaker artifact permits confirmation of pulse width as well as programmability and facilitates discovery of pacemaker hardware failures otherwise undetectable. Continuous recording of real‐time surface ECG can be made as other measurements or storing functions are being performed. In this way, sporadic or infrequent intrinsic events are automatically recorded and can be selected to be played back and reviewed or stored on the permanent record. Pacemaker spike detection enhances identification of paced and intrinsic complexes by emphasizing the paced artifact. Even bipolar atrial spikes with pulse widths as short as 0.05 ms are easily identified; myopotential muscle noise is rejected. Enhancement of pacemaker spikes takes the guesswork out of interpretation of ECGs, especially for bipolar systems and when testing or troubleshooting for myopotential tracking or inhibition.
A New System for Follow‐Up Patients with Permanent Pacemakers
Authors: BROFFONI T. , BONINI W. , FERRARI G.
Published: October 2007

BROFFONI, T., ET AL.: A New System for Follow‐Up Patients with Permanent Pacemakers. The use of a new computerized system for coordinating technical and clinical data and especially for filing the parameters found during out‐patient checkups enables us to rationally carry out follow‐up of approximately 900 patients with pacemakers in our electrostimulation laboratory without wasting time or data. The system is composed of a personal Olivetti M240 computer, with a 20 Bbyte and 640 Kram hard disk, an analog‐digital interface and a personalized data base for coordinating and filing the parameters found. The type of pacemaker implanted (monocameral, dual chamber or rate responsive) is of no consequence to the system that is based on the acquisition of the surface electrocardiogram. A comparison of the filed data on printouts or graphs allows us to note every type of misfunction or anomaly in the stimulation system in real time.
“Pacecare”‐A Computerized Database for Pacemaker Follow‐Up
Authors: STRATHMORE N. , MOND H. , HUNT D. , GRAHAM D. , COWLING R. , HALE G. , PATE B.
Published: October 2007

STRATHMORE, N., ET AL.: “Pacecare”‐A Computerized Database for Pacemaker Follow‐Up. A computerized database for pacemaker follow‐up has been designed to run on IBM compatible hardware and to accept pulse generator and lead models of all manufacturers. Stored data includes patient, physician and implant details, indications for pacing, underlying rhythm, complications and management, program settings, and follow‐up measurements. Typing is minimized by the use of “pop‐up” lists and prepared pulse generator template displays. At each follow‐up visit a patient's file is retrieved by surname or number, a visit record created, and measurements documented. As the template of the previous visit is used, recording of the clinic visit takes < 1 minute. Changes in pacing rates (base or magnet), pulse widths, lead thresholds, lead impedance, and battery cell impedance can be displayed graphically for immediate recognition of end‐of‐life parameters or suspected malfunction. The program will print patient, implantation and clinic visit summary reports, clinic appointment lists, letters to patients, and annual reports. Two Melbourne hospitals have now entered over 3,600 patients into the database. Valuable information has been obtained regarding implantation details and trends with pulse generator and lead usage. Pacecare is a sophisticated, yet user friendly, computerized database for pacemaker follow‐up. Recording of clinic visits is fast and changes in testing parameters can be recognized immediately.
Relationship Between Right Atrial and Mixed Venous Oxygen Saturation and Heart Rate During Exercise in Normal Subjects and Patients with Cardiac Disease
Authors: FRENCH WILLIAM J. , CASABURI RICHARD , LEWIS DAVID A. , DALY JAMES A. , FLORIO JOSEPH , WESLEY GEORGE W.
Published: October 2007

FRENCH, W.J., ET AL.: Relationship Between Right Atrial and Mixed Venous Oxygen Saturation and Heart Rate During Exercise in Normal Subjects and Patients with Cardiac Disease. An ideal sensing variable for use in rate responsive pacemakers should measure a physiological parameter that closely correlates with heart rate during various activities in a diverse group of subjects. Nineteen patients, 12 normal and 7 patients with heart disease, were studied to assess the relationship between mixed venous oxygen saturation and heart rate. In patients with heart disease right atrial oxygen saturation and heart rate were also compared. Each subject underwent pulmonary artery catheterization and performed seated cycle ergometer exercise. Gas exchange and heart rate were measured continuously and blood sampled at frequent intervals. Normal patients were studied at rest and during steady‐state exercise (mean work rate 149 watts). Patients were studied at rest, steady‐state exercise [mean work rate 37 watts), and during incremental exercise (5–10 wattsimin) to tolerance. There were 248 paired right atrial or mixed venous oxygen saturation/heart rate observations obtained. Changes in mixed venous oxygen saturation and heart rate were not substantially altered by fitness or cardiac disease. Rate responsive pacemakers sensing changes in oxygen saturation may be a superior sensing variable for both normal and patients with heart disease.
Intrapatient Comparison Between Chronic VVIR and DDD Pacing ‘In Patients Affected by High Degree AV Block Without Heart Failure
Authors: MENOZZI CARLO , BRIGNOLE MICHELE , MORACCHINI PIER VITTORIO , LOLLI GINO , BACCHI MIRKA , TESORIERI MARIA CRISTINA , TOSONI GIAN DOMENICO , BOLLINI ROBERTO
Published: October 2007

MENOZZI, C., ET AL.: Intrapatient Comparison Between Chronic VVIR and DDD Pacing in Patients Affected by High Degree AV Block Without Heart Failure. In patients affected by high degree AV block without preexisting congestive heart failure there is no definite demonstration that DDD pacing gives real clinical advantages in respect to VVIR pacing. We performed an intrapatient, long‐term study between the two pacing modes in 14 high degree AV block patients, using the Medtronic Synergyst 7027 dual chamber pacemaker, who could be programmed alternatively in DDD or VVIR mode. After a 4‐week run‐in period following the pacemaker implant, patients completed a randomized, double‐blind, cross‐over study to compare the effect of 6‐week period VVIR and DDD pacing on symptoms and cardiovascular parameters. A semiquantitative score scale was used to quantify the symptoms of general well‐being, palpitations, dizziness, pulsating sensation in the neck or abdomen, shortness of breath at rest and during effort, chest pain, and NYHA classification. The sum of symptom scores was 10.4 ± 6.7 in VVIR period and 4.6 ± 2.7 in DDD period (p < 0.001); five patients (36%) crossed over early from VVIR to DDD because of intolerable symptoms; overall, eight patients preferred the DDD mode and no one preferred the VVIR. Cardiac output at rest (echo‐Doppler method) was 4.7 ± 1.4 versus 5.7 ± 1.6 liter/min (p < 0.01), body weight was 65.9 ± 6.6 versus 64.9 ± 6.1 kg (p < 0.02), atrial natriuretic peptide was 236 ± 112 versus 198 ± 110 pg/mL (p < 0.01), respectively, during VVIR and DDD modes. Effort tolerance was similar with the two modes of pacing (68 ± 15 vs 70 ± 18 watt/min). In conclusion, hemodynamic advantages of atrial synchronization reflect a better quality of life for the patients even if an individual variability exists.
Pacing in Atrial Arrhythmias
Authors: SUTTON RICHARD
Published: October 2007

SUTTON, R.: Pacing in Atrial Arrhythmias. The history of pacing to control the atrial arrhythmias of sinoatrial node disease (SND) is reviewed and is demonstrated to have become more physiological in recent years. The importance of atrial stimulation is emphasized especially in the context of the natural history of SND. The role of single and dual chamber rate responsive pacing for correction of chronotropic incompetence is outlined and guidelines are proposed for the management of the different types of SND presentation.
A New Feature for Control of Inappropriate High Rate Tracking in DDDR Pacemakers
Authors: LEE MICHAEL T. , ADKINS ALAN , WOODSON DRURY , VANDEGRIFF JOE
Published: October 2007

LEE, M.T., ET AL. A New Feature for Control of Inappropriate High Rate Tracking in DDDR Pacemakers. A limitation of current DDD and DDDR pacemakers is the inability to distinguish between inappropriate high rate atrial sensed events that are physiologically appropriate to track (e.g., elevated sinus rates resulting from exercise, emotional responses, etc.) and those that are physiologically inappropriate to track (e.g., paroxysmal atrial dysrhythmias, myopotentials, retrograde conduction, etc.). The sophistication of sensing circuitry is not yet sufficiently advanced to permit a pacemaker to distinguish appropriate atrial events by morphology. The addition of an independent sensor to a DDD pacemaker (i.e., DDDR) gives more information about the patient's condition, especially with respect to exercise. This information can be used to judge the appropriateness of a high sensed atrial rate, and to modulate the pacemaker's response. If the sensor input is below a specified level, indicating lack of exercise, the DDDR can track sensed atrial events only to a tolerably low limit‐the conditional ventricular tracking limit (CVTL). Wenckebach‐type behavior ensues at the CVTL until the sensor input increases, indicating that exercise is occurring, or until the sensed atrial rate decreases. If the sensor input indicates exercise, the DDDR pacemaker can track up to the programmed maximum rate. Two DDDR systems have been developed that incorporate this feature; one based on temperature, the other on activity. Currently the CVTL is set at a value about 30 ppm above the pacing rate, as a compromise to support emotional needs not seen by the sensor. Improved sensors could cause the decision to raise the tracking limit (i‐e., recognition of physiological need for higher rates) to be more accurate, perhaps making the CVTL proportional to the sensor signal.
Intravascular Lead Extraction Using Locking Stylets and Sheaths
Authors: BYRD CHARLES L. , SCHWARTZ SUSAN J. , HEDIN NANCY B. , GOODE LOUIS B. , FEARNOT NEAL E. , SMITH HEIDI J.
Published: October 2007

BYRD, C.L., ET AL.: Intravascular Lead Extraction Using Locking Stylets and Sheaths. Chronic lead extraction using intravascular countertraction techniques was studied in patients with over 65 different lead models including passive and active fixation devices. Indications for removal of 115 leads implanted 5 days to 264 months (mean 58 months) in 62 patients (mean 65 years) included septicemia, subcutaneous tissue infection, preerosion, free‐floating lead, lead trapped in valve, too many leads, pain, and vein thrombosis. The superior vena cava (SVC) approach was attempted in 101 leads and was successful in 82 attempts (71% of total leads). The inferior vena cava (IVC) approach via the femoral vein was required to extract 14 (12%) leads inaccessible to the SVC approach and the 19 leads that failed the SVC approach (29% of total leads). The SVC procedure includes a sized stylet locked at the tip and telescoping sheaths advanced over the lead to the heart. An IVC procedure includes placement of a 16 F sheath workstation via a femoral vein into the right atrium. A deflection catheter and Dotter snare in an 11 F sheath were advanced through the workstation into the right atrium. The lead was maneuvered into position, snared, and pulled into the workstation. For both the SVC and IVC approaches, the leads were removed by applying traction on the lead and countertraction with the sheaths. In experienced hands, these techniques have proven safe and effective for removing chronic transvenous leads.
In Vivo Elution Rate of Drug Eluting Ceramic Leads with a Reduced Dose of Dexamethasone Sodium Phosphate
Authors: MATHIVANAR RANJINI , ANDERSON NEIL , HARMAN DEIRDRE , SKALSKY MICHAEL , NG MICHAEL
Published: October 2007

MATHIVANAR, R., ET AL.: In Vivo Elution Rate of Drug‐Eluting Ceramic Leads with a Reduced Dose of Dexamethasone Sodium Phosphate. We have evaluated the in vivo elution rate and the threshold voltage performance of a new lead incorporating a controlled delivery device based on a porous ceramic collar. The drug, dexamethasone sodium phosphate (DSp < 0.2 mg), was contained within the pores of a ceramic collar that was positioned externally and adjacent to a 4 mm2 Pt/Ir coated electrode. Thirty‐three leads comprising a porous ceramic drug eluting collar (DEC) were implanted in the right ventricle of 12 sheep. In vivo elution was determined by analyzing the drug remaining in the collar after 1, 3, 11, and 28 days. Voltage thresholds were measured at implant and then weekly for 28 days on three sheep. Results were compared to leads with identical electrodes but with silicone DEC (DSp < 0.5 mg). The in vivo elution rate of the ceramic DEC leads was fast with approximately 90% of the drug content eluted on the first day. By comparison, the silicone DEC released approximately 50% of the drug content on the first day. Although the drug content and elution rates were different for the ceramic and silicone DEC leads, the threshold performance of the leads was similar. For ceramic and silicone DEC leads, threshold voltages at implant and at 4 weeks were 0.29 ± 0.09 compared to 0.37 ± 0.08 and 0.42 ± 0.08 compared to 0.44 ± 0.13, respectively. The results show that a relatively rapid release of a reduced dose of DSP from a DEC is still effective in reducing threshold peaking.