bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Spontaneous Seizures after Experimental Status Epilepticus: Implications for Understanding Epileptogenesis
Authors: Williams Philip A. , Hellier Jennifer L. , White Andrew M. , Staley Kevin J. , Dudek F. Edward
Published: October 2007

Summary:  This report examines several concepts concerning the latent period to the first convulsive seizure, subsequent increases in seizure frequency, and possible mechanisms of epileptogenesis after kainate‐induced status epilepticus. Previous data concerning the latent period and seizure progression from intermittent and continuous behavioral monitoring are compared, and hypothetical mechanisms of acquired epilepsy are discussed. Data involving electrographic recordings with tethered animals or with radiotelemetry are assessed in terms of their potential for addressing different hypotheses concerning the latent period and progressive changes in seizure frequency. Experimental analyses of the time course of occurrence of spontaneous seizures are interpreted in terms of possible cellular mechanisms underlying epileptogenesis.
Effect of DOV 102,677 on the Volitional Consumption of Ethanol by Myers’ High Ethanol‐Preferring Rat
Authors: McMillen Brian A. , Shank J. Elizabeth , Jordan Kirstin B. , Williams Helen L. , Basile A. S.
Published: October 2007

Background:  Inhibitors of monoamine neurotransmitter transporters are well established as antidepressants. However, the evidence that single (serotonin) or dual (serotonin–norepinephrine) neurotransmitter uptake inhibitors can treat ethanol abuse, either as a comorbidity with depression or as a separate entity, is inconsistent. Drugs that have, in addition, the ability to inhibit dopamine uptake may have an advantage in the treatment of alcohol abuse. Therefore, the inhibitor of norepinephrine, serotonin and dopamine uptake, DOV 102,677, was tested for its effects on the volitional consumption of ethanol by an ethanol‐preferring rat strain.

Methods:  Myers’ high ethanol‐preferring rats were screened by a 10‐day, 3 to 30% step‐up test and then given free access to the preferred concentration of ethanol in a 3‐bottle choice task. Consumption of ethanol (g/kg), water, food, and body weight were measured daily during a 3‐day predrug treatment period, a 3‐day treatment period, and a 3‐day posttreatment period. Additional Sprague–Dawley rats were observed for 24 hours for the behavioral effects of 2.0 mg/kg s.c. reserpine after a 30‐minute pretreatment with different doses of DOV 102,677.

Results:  The triple monoamine uptake inhibitor DOV 102,677 dose‐dependently decreased the volitional consumption of ethanol by as much as 71.2% (20 mg/kg i.p., b.i.d.) over 3 days of administration. This effect carried over into the posttreatment period. Similarly, the proportion of ethanol to total fluids consumed declined by 66.2% (20 mg/kg s.c., b.i.d.), while food consumption and body weight were unaltered. In contrast, amperozide (2 mg/kg i.p., b.i.d.) suppressed the amount of ethanol consumed by 56%, while naltrexone (5 mg/kg i.p., b.i.d.) was without effect. DOV 102,677 (40 mg/kg s.c.) inhibited reserpine‐induced akinesia and ptosis, but not hypothermia in Sprague–Dawley rats, consistent with its transient inhibition of serotonin transport, and more long‐lived inhibition of norepinephrine and dopamine uptake.

Conclusions:  DOV 102,677 significantly decreased the volitional consumption of ethanol with minimal alterations in the intake of food or on body weight in an ethanol‐preferring rat strain, suggesting that triple reuptake inhibitors may find utility in treating alcohol abuse.
Mutual Optimism and War
Authors: Fey Mark , Ramsay Kristopher W.
Published: October 2007

Working with the definition of mutual optimism as war due to inconsistent beliefs, we formalize the mutual optimism argument to test the theory's logical validity. We find that in the class of strategic situations where mutual optimism is a necessary condition for war—i.e., where war is known to be inefficient, war only occurs if both sides prefer it to a negotiated settlement, and on the eve of conflict war is self‐evident—then there is no Bayesian‐Nash equilibrium where wars are fought because of mutual optimism. The fundamental reason that mutual optimism cannot lead to war is that if both sides are willing to fight, each side should infer that they have either underestimated the strength of the opponent or overestimated their own strength. In either case, these inferences lead to a peaceful settlement of the dispute. We also show that this result extends to situations in which there is bounded rationality and/or noncommon priors.
Clientelism, Credibility, and the Policy Choices of Young Democracies
Authors: Keefer Philip
Published: October 2007

This article identifies for the first time systematic performance differences between younger and older democracies and argues that these are driven by the inability of political competitors to make broadly credible preelectoral promises to voters. Younger democracies are more corrupt; exhibit less rule of law, lower levels of bureaucratic quality and secondary school enrollment, and more restrictions on the media; and spend more on public investment and government workers. This pattern is exactly consistent with the predictions of Keefer and Vlaicu (n.d.). The inability of political competitors to make credible promises to citizens leads them to prefer clientelist policies: to underprovide nontargeted goods, to overprovide targeted transfers to narrow groups of voters, and to engage in excessive rent seeking. Other differences that young democracies exhibit, including different political and electoral institutions, greater exposure to political violence, and greater social fragmentation, do not explain, either theoretically or empirically, these policy choices.
Mechanism of Motivated Reasoning? Analogical Perception in Discrimination Disputes
Authors: Braman Eileen , Nelson Thomas E.
Published: October 2007

This article examines the boundaries of motivated reasoning in legal decision making. We propose a model of attitudinal influence involving analogical perception. Attitudes influence judgments by affecting the perceived similarity between a target case and cases cited as precedent. Bias should be most apparent in judging similarity when cases are moderately similar on objective dimensions. We conducted two experiments: the first with undergraduates, the second with undergraduates and law students. Participants in each experiment read a mock newspaper article that described a “target case” involving unlawful discrimination. Embedded in the article was a description of a “source case” cited as legal precedent. Participants in both studies were more likely to find source cases with outcomes that supported their policy views in the target dispute as analogous to that litigation. Commensurate with our theory, there was evidence in both experiments that motivated perceptions were most apparent where cases were moderately similar on objective dimensions. Although there were differences in the way lay and law student participants viewed cases, legal training did not appear to attenuate motivated perceptions.
Against Anthropocentrism: A Jobian Appeal to Science on Theology's Behalf
Authors: Sponheim Paul
Published: October 2007

Abstract:  The author asks how science can affect the work of the theologian and uses the experience of Job in the “wild” as pointing toward a new seeing. From science's study of temporality the theologian may learn (1) that humans belong with the (other) creatures, against anthropocentrism, (2) that the traditional distinction between creation and preservation inadequately recognizes God's continuing creative work, and (3) that Christian soteriology needs to address the “groaning” (Romans 8) of the whole creation. While science may help the theologian see thus newly, theology needs to retain its own integrity, as represented by the distinction between creation and fall.
Coexistence of Complete Infra‐Hisian Block, WPW Syndrome and Mobitz Type II Kent Bundle Block
Authors: MOSSUTI ERNESTO , ELIA FRANCO , MARTELLO GIUSEPPE , BRANCATI BENEDETTO
Published: October 2007

MOSSUTI, E., ET AL.: Coexistence of Complete Infra‐Hisian Block, WPW Syndrome and Mobitz Type II Kent Bundle Block. A 65‐year‐old patient with a chief complaint of syncope had an ECG with ventricular preexcitation and intermittent second‐degree atrioventricular [AV] block. AV conduction was maintained by the accessory pathway only, with no evidence of AV nodal conduction. Electrophysiological study demonstrated that the QRS duration and morphology did not increase with atrial pacing; however, A‐H prolongation occurred with increased pacing rates.
Pacemaker Mediated Tachycardias In Single Chamber Rate Responsive Pacing
Authors: LAU CHU‐PAK , TAI YAU‐TING , FONG PING‐CHING , CHENG CHUN‐HO , CHUNG FELSA LAI‐WAH
Published: October 2007

LAU, C.‐P., ET AL.: Pacemaker Mediated Tachycardias In Single Chamber Rate Responsive Pacing. Although pacemaker mediated tachycardias are classically associated with dual chamber pacemakers, single chamber rate responsive pacemakers are also susceptible to such tachycardias under special circumstances. A unipolar activity sensing rate responsive pacemaker (Activitrax 8403) was implanted in an 83‐year‐old man with complete atrioventricular block. The pacemaker was programmed at an output of 5 V, activity threshold medium, rate response 5, and lower and upper rates of 70 and 125 beats/min, respectively. He presented with palpitations at rest and muscle twitching of the pacemaker pocket 4 months after implantation. Examination confirmed that the pacemaker had flipped over, resulting in pocket pacing which in turn activated the activity sensor, resulting in a rate response. The increase in pacing rate lead to a higher frequency of pocket pacing, thus leading to positive feedback increase in rate. With the patient at rest, pacemaker mediated rates were 106, 91, and 74 beats/min at low, medium and high thresholds, respectively. Decreasing the output to 2.5 V eliminated pocket pacing and the tachycardia. As a result of the reversal of the pacemaker, a similar rate response during exercise could only be achieved at a more sensitive rate responsive setting. Thus, pacemaker mediated tachycardia can complicate pacemaker “flipping” in single chamber activity sensing rate responsive pacemakers. Methods for the avoidance and treatment of pacemaker flipping are discussed. A review of other sensor mediated tachycardias is also presented.
The Effect of Multiple Shocks on Canine Cardiac Defibrillation
Authors: FLAKER GREG , SCHUDER JOHN , MCDANIEL WAYNE
Published: October 2007

FLAKER, G., ET AL.: The Effect of Multiple Shocks on Canine Cardiac Defibrillation. To determine if multiple shocks adversely affect the success of later shocks compared with early shocks, we analyzed the success rates of initial shocks (defibrillation attempts 1–5), first half shocks (defibrillation attempts 1–20) and second half shocks [defibrillation attempts 21–40) in a canine model. Epicardial patches were placed on the right and left ventricle in 28 dogs. Ventricular fibrillation was induced by a 60‐Hz shock. After 30 seconds, defibrillation was attempted using 7, 12, 13, or 18 joules with either a uniphasic or biphasic rectangular waveform. The uniphasic waveform was 5 msec in duration; the biphasic waveform was 10 msec, with the lagging 5‐msec pulse one‐half the amplitude of the leading 5‐msec pulse. For uniphasic shocks, the right ventricular patch was positive; for biphasic shocks, the right ventricular patch was positive during the leading 5 msec of the shock and negative during the lagging milliseconds. A total of 960 fibrillation episodes were evaluated; no dog was involved in more than 40 fibrillation episodes. The success rates of defibrillation attempts 1–5, defibrillation attempts 1–20, and defibrillation attempts 21–40 were similar at 12, 13, and 18 joules. This information supports the continued use of up to 40 fibrillation trials in canine cardiac defibrillation. However, at 7 joules defibrillation attempts 21–40 were more successful than defibrillation attempts 1–5, and 1–20. With our methodology, these data are consistent with the hypothesis that low energy shocks create a “sensitizing” effect on cardiac tissue, allowing more successful defibrillation with repeated shocks.
Physical Determinants of the Endocardial P Wave
Authors: SHANDLING ADRIAN H. , FLORIO JOSEPH , CASTELLANET MARK J. , MESSENGER JOHN C. , CRUMP RANDY , EVANS KARLA , RYLAARSDAM ARLENE , NOLASCO MARIA
Published: October 2007

SHANDLING, A.H., ET AL.: Physical Determinants of the Endocardial P Wave. Reliable atrial sensing of intrinsic P wave activity is important to ensure optimal atrial or dual chamber pacemaker function. Various physical factors (e.g., posture, respiration, exercise) may influence P wave characteristics and impair adequate sensing. To investigate this phenomenon, we measured the average of three P wave amplitudes (PWA) and calculated slew rates from telemetered printouts acquired from Pacesetter pacemakers in 32 patients. These measurements were performed in various body positions, with upright exercise and in varying stages of respiration. Results: the mean supine PWA increased on full inspiration (3.56 ± 1.3 mV versus 3.25 ± 1.2 mV during quiet respiration, p < 0.001), and also increased significantly with full expiration. The mean PWA increased on assuming the erect position (3.25 ± 1.2 mV increasing to 3.49 ± 2.3 mV, p < 0.001); in the upright position, the mean erect PWA during quiet respiration was not significantly influenced by the stage of respiration. The mean upright exercise PWA did not differ significantly from the preexercise erect PWA (3.50 f 1.2 with exercise, and 3.47 ± 1.5 before exercise; P = NS). Calculated slew rates were not different lying versus standing. Conclusions: the mean supine PWA increases significantly at the extremes of respiration and on assuming the erect body position; upright exercise results in no appreciable change in the erect PWA. Atrial sensitivity adjustments based on standard supine testing should be adequate for all body positions. (PACE, Vol. 13, December, Part I 1990)
Intraventricular Electrogram Analysis for Ventricular Tachycardia Detection: Statistical Validation
Authors: THRONE ROBERT D. , JENKINS JANICE M. , DiCARLO LORENZO A.
Published: October 2007

THRONE, R.D., ET AL.: Intraventricular Electrogram Analysis for Ventricular Tachycardia Detection: Statistical Validation. Time‐domain analysis of intraventricular electrogram morphology during ventricular tachycardia (VT) and sinus rhythm or atrial fibrillation (SR/AF) has been proposed as a method for increasing the specificity of pathological tachycardia detection by antitachycardia devices. However, few studies have validated the use of such analysis with statistical methods. When statistical methods have been utilized, it has been assumed that the distribution of the values derived from analysis of the intracardiac electrograms have had a normal (gaussian) distribution. In this study, we sought to determine whether: (1) the distribution of values derived from analysis of intracardiac electrogram during SR/AF and VT is gaussian or nongaussian; and (2) the discrimination of monomorphic VT from SR/AF using SR/AF templates can be validated statistically. Two previously proposed time‐domain methods—correlation waveform analysis (CWA) and area of difference (AD)—were selected for evaluation of 29 patients with 33 distinct, sustained monomorphic VTs. An initial SR/AF template was used to analyze subsequent SR/AF and VT passages with a minimum of 50 consecutive depolarizations using a “best‐fit” alignment. The values derived from each analysis were examined subsequently for skewness (asymmetry) and kurtosis (shape) using two‐tailed tests (p < 0.02). For passages of SR/AF, a normal (gaussian) distribution was present in only 24% (CWA), and 45% (AD); for passages of VT, normal distribution was present in only 58% for both CWA and AD. Using appropriate statistical testing with nonparametric tolerance intervals, CWA and AD discriminated VT from SR/AF in 29 out of 33 (88%), and 30 out of 33 (91%) instances, respectively, with 95% confidence. Thus, the assumption of a gaussian distribution for values derived from time‐domain analysis of intraventricular electrograms for VT detection is not uniformly valid. Both CWA, which is independent of both baseline and amplitude fluctuations, and AD, which is not independent of these fluctuations, have similar performance when validated with appropriate statistical methods.
Stability of Pacing Threshold, Impedance, and R Wave Amplitude at Rest and During Exercise
Authors: SCHUCHERT A. , KUCK K.‐H. , BLEIFELD W.
Published: October 2007

SCHUCHERT, A., ET AL.: Stability of Pacing Threshold, Impedance, and R Wave Amplitude at Rest and During Exercise. The pacing threshold of the human heart may be altered by physiological factors such as physical exercise. These changes may influence the individual programming of a pacemaker, since pacemakers can be programmed at pulse amplitudes of 2.5 volts and Jess. We investigated 22 patients with a multiprogrammable ventricular demand pacemaker 3 months after implantation; 16 patients had received a steroid‐eluting lead and six patients had an Elgiloy lead. Parameters measured at rest and immediately after exercise were: Voltage threshold at pulse durations between 0.05 and 0.6 ms, impedance, R wave amplitude and energy consumption for the pacing threshold at 0.5 ms pulse duration. All patients performed a symptom limited supine bicycle exercise test. None of the investigated parameters showed a significant difference between rest and exercise, neither for the steroid eluting lead nor for the Elgiloy lead. The data suggest that the individual programming of a pacemaker adapted to the measurements at rest is also reliable and safe during exercise.
Catheter Ablation of Accessory Pathways: Technique and Results in 248 Patients
Authors: WARIN JEAN‐FRANÇOIS , HAISSAGUERRE MICHEL , D'IVERNOIS CHRISTOPHE , MÉTAYER PHILIPPE LE , MONTSERRAT PAUL
Published: October 2007

WARIN, J.‐F., ET AL.: Catheter Ablation of Accessory Pathways: Technique and Results in 248 Patients. Two hundred and forty‐eight patients with refractory arrhythmias related to an accessory pathway underwent catheter ablation. Cathodal shocks (I60 to 240 joules) were delivered through the distal electrode of a standard catheter (usually a quadripolar electrode catheter with 5‐mm interelectrode distances). A paddle electrode positioned opposite to the catheter served as the anode. Ablation of 24 right anteroseptal, 16 right parietal, 86 posteroseptal, 120 left parietal and four Mahaim pathways was clinically successful in eliminating symptomatic tachycardia in 236 patients (>96%) over a follow‐up of 3 to 64 months. There was no procedure‐related death but two patients developed a ventricular fibrillation at the fifth and seventh day, respectively. The latter led to a sudden death since this side effect occurred after discharge. There were no instances of systemic embolus but one pericardial effusion required subxiphoid needle drainage 6 weeks after the procedure. Other complications included: AV block in four patients with posteroseptal and in one with a right anterior septal pathway. In conclusion, a successful clinical outcome may be achieved in most patients. Catheter ablation is an important alternative to cardiac surgery and in our opinion represents first‐line treatment when therapy is required.
Longitudinal Dissociation within the Reentry Pathway of Ventricular Tachycardia
Authors: SATULLO GAETANO , ORETO GIUSEPPE , DONATO ANTONINO , FERRARA MARIA C. , LUZZA FRANCESCO , COGLITORE SEBASTIANO
Published: October 2007

SATULLO, G., ET AL.: Longitudinal Dissociation within the Reentry Pathway of Ventricular Tachycardia. Two cases of nonsustained, repetitive ventricular tachycardia are analyzed. In both, the episodes of tachycardia do not contain random numbers of beats, but the complexes in each phase of tachycardia are either always in even numbers (case 1) or always in odd numbers (case 2). This indicates longitudinal dissociation within the reentry circuit: i.e., there are two functionally separate pathways in some part of the reentry circuit, and the reciprocating impulse runs alternatively through the two pathways. Tachycardia ends due to block of the impulse always in the same pathway, thus, the number of beats in each episode of tachycardia is always either in odd or even numbers. (PACE, Vol. 13, December, Part 1 1990)
Linking: A Mechanism of Intermittent Preexcitation in the Wolff‐Parkinson‐White Syndrome
Authors: MIDDLEKAUFF HOLLY R. , STEVENSON WILLIAM G. , KLITZNER THOMAS S.
Published: October 2007

MIDDLEKAUFF, H.R., ET AL.: Linking: A Mechanism of Intermittent Preexcitation in the Wolff‐Parkinson‐White Syndrome. Intermittent preexcitation in the Wolff‐Parkinson‐White syndrome has been equated with a long accessory pathway refractory period and long R‐R interval between preexcited beats in atrial fibrillation and therefore a low risk for sudden death. A case of Wolff‐Parkinson‐White syndrome in which preexcitation became intermittent following procainamide infusion, with only moderate prolongation of the accessory pathway refractory period but marked prolongation of the shortest preexcited R‐R interval in atrial fibrillation, is described. Programmed ventricular and atrial stimulation demonstrated that intermittent preexcitation was caused by concealed conduction producing a linking phenomenon, facilitated by the antiarrhythmic drug. Linking due to concealed retrograde penetration of a propagated impulse into the accessory pathway may contribute to the disparity between accessory pathway refractory period and shortest preexcited R‐R interval in atrial fibrillation in some patients and may be a confounding factor in the interpretation of noninvasive tests of accessory pathway conduction.
The Effects of Percutaneous Catheter Ablation on Preexisting Permanent Pacemakers
Authors: VANERIO GABRIEL , MALONEY JAMES , RASHIDI RASSOLL , MCCOWAN RONALD , CASTLE LON , MORANT VICTOR , WILKOFF BRUCE , SIMMONS TONY
Published: October 2007

VANERIO, G., ET AL.: The Effects of Percutaneous Catheter Ablation on Preexisting Permanent Pacemakers. Study Objective: Determine the effect of percutaneous catheter ablation (CAI on permanent pacemakers. Measurements and Results: Twenty‐three patients who underwent CA at The Cleveland Clinic Foundation from September 1983 to January 1990, and had a previously implanted pacemaker were studied. Electrocardiographic data during the CA procedure and clinic data including pacemaker evaluations were analyzed. Fifty‐two percent (12/23) of the pacemakers malfunctioned: five developed transient ventricular loss of capture; two undersensing; one oversensing; three could not be interrogated or programmed, and one did not respond to the magnet test. Four patients developed syncopal episodes and two severe dizziness after the procedure. All had their pacemakers replaced. In total, seven were explanted. Destructive analysis by the individual manufacturer identified pacemaker circuitry failure in five. Unipolar pacemakers and anodal ablation procedures had more frequent and severe malfunctions, but the difference was not statistically significant. Conclusions: Pacemaker malfunction is frequent during CA. It may be prevented by programming the pacemaker, when possible, to the nonfunctioning mode (000 mode). Temporarily disconnecting the pacemaker during ablation requires further evaluation as an alternative approach. Close follow‐up can detect pacemaker malfunction and prevent complications.
Dynamic Electrophysiology of Ventriculoatrial Conduction: Implications for DDD and DDDR Pacing
Authors: CAZEAU SERGE , DAUBERT CLAUDE , MABO PHILIPPE , RITTER PHILIPPE , LELONG BERNARD , POUILLOT CHRISTOPHE , PAILLARD FRANCOIS
Published: October 2007

CAZEAU, S., ET AL.: Dynamic Electrophysiology of Ventriculoatrial Conduction: Implications for DDD and DDDR Pacing. The behavior of ventriculoatrial conduction (VAC) during exercise remains unknown. In order to determine its characteristics and the consequences it might have on dual chamber pacemaker technology and programming, 17 patients underwent an electrophysiological study (EPS) of atrioventricular conduction (AVC) and of VAC during a protocol including three steps: supine rest, upright position, and finally during cycloergometric exercise; the measurements were done at progressively increasing pacing rates. During a preimplantation EPS, Wenckebach points AVC‐W and VAC‐W and conduction times, AVCT and VACT (as a function of pacing rate), were measured in ten consecutive patients using temporary leads and an external device. In another study, AVCT, VACT, AVC‐W, and VAC‐W were measured by telemetric recordings under identical conditions in seven patients implanted earlier with a DDD pacemaker. A 1/1 VAC was observed in 7/17 patients (41%) at rest, and in 13/17 patients (76%) at the end of the protocol; VAC was never observed in 4/17 patients [23%], but occurred in six of the ten patients initially free, three standing at rest and three on exercise. For all patients, the VAC behavior remained of “nodal” type, indicated by a progressive increase in VACT as pacing rate rose up to the VAC‐W point. Neither the existence of exercise‐induced VAC nor the maximal VACT‐W could be predicted from AVC or VAC data obtained at rest. However, at the same pacing rates, standing up and exercise induced a shortening effect on VACT, and improved the VAC‐W by an average of 33%. These results suggest that the electrophysiological behavior of VAC does not obey any general rule and cannot be predicted individually. It would thus appear unwise to base pacemaker mediated tachycardia (PMT) protection solely on long postventricular atrial refractory period (PVARP) programming in DDD patients. This work also revealed the potential risks of a rate responsive auto‐adaptive PVARP algorithm as proposed in certain new devices.
The A‐R Interval as Exercise Indicator: A New Option for Rate Adaptation in Single and Dual Chamber Pacing
Authors: RUITER JAAP H. , BOER HANS DE , BEGEMANN MALCOLM J.S. , MECHELEN ROB VAN
Published: October 2007

RUITER, J.H., ET AL.: The A‐R Interval as Exercise Indicator: A New Option for Rate Adaptation in Single and Dual Chamber Pacing. We investigated the possibility to use the interval from an atrial stimulus to the Ventricular R wave [A‐R interval) as an indicator of physical stress, in 16 patients with pacemakers implanted for severe atrial bradycardia but with intact AV conduction. The A‐R interval was studied during incremental atrial pacing at rest and during exercise with a constant workload. In addition, the atrial pacing rate was kept constant just above spontaneous sinus rate and the dynamics of the A‐R interval were studied during exercise with a low constant workload and during a maximal exercise test with increasing workload. Incremental atrial pacing prolonged the A‐R interval and this response was blunted during exercise [p < 0.003). Atrial pacing at a constant rate and during a constant workload resulted in an almost direct shortening of the A‐R interval. When the workload was increased but the atrial rate kept constant, a pronounced shortening of the A‐R interval was noted [p < 0.0001). It is concluded that changes of the A‐R interval during different kinds of exercise were prompt and predictable in patients with sinus node dysfunction but intact AV conduction. In these patients the shortening of the A‐R interval during exercise may be a suitable indicator for rate adaptive atrial pacing.
A Reappraisal of Atrioventricular Nodal Excitability During Functional 2:1 Block: What Should be the Gauge?*
Authors: YOUNG MING‐LON
Published: October 2007

YOUNG, M.‐L.: A Reappraisal of Atrioventricular Nodal Excitability During Functional 2:1 Block: What Should be the Gauge? By using extrastimulation technique the effective refractory period (ERP) of the atrioventricular (AV) node is conventionally defined as the longest A1 A2 interval at which conduction of A2 is blocked within the node. With the prolongation of the AV nodal transit time that is associated with this technique, the delayed AV nodal arrival of the A1 impulse will cause an overestimation of the true interval if the A1 A2 interval is used as the gauge. Under this condition, the conventional approach will not accurately delineate the ERP of the AV node. However, this prolongation of the nodal transit time can be calculated by subtracting the basal conduction time from the conducted A‐H interval. By subtracting out the prolongation from the longest A1 A2 at which A2 impulse is blocked, not only an interval more indicative of the true AV nodal ERP can be obtained, but also the apparent discrepancies between the in vitro and human AV nodal recovery curves disappear.
Endless‐Loop Tachycardias: Description and First Clinical Results of a New Fully Automatic Protection Algorithm
Authors: NITZSCHÉ RÉMI , GUEUNOUN MAXIME , LAMAISON DOMINIQUE , LASCAULT GILLES , PIOGER GUY , RICHARD MAURICE , MALHERBE ODILE , LIMOUSIN MARCEL
Published: October 2007

NITSCHÉ, R., ET AL.: Endless‐Loop Tachycardias: Description and First Clinical Results of a New Fully Automatic Protection Algorithm. Endless‐loop tachycardia ELT) is one of the most common pacemaker mediated tachycardia. An innovative ELT protection algorithm has proven to be clinically effective. A new improved version that will eliminate the need to program any parameter is now under clinical evaluation. Nine patients entered the study: six men and three women, aged 52 ± 22 years. This automatic algorithm needs only 10 cycles to detect and confirm an ELT. Three hundred thirty‐three ELTs lasting more than 9 cycles have been induced and analyzed. The total results are the following: mean duration: 6.7 sec ± 3.1; mean ELT rate: 137 ± 21.9 bpm, mean programmed upper rate limit (URL): 142.5 ± 26.5 bpm (Only 70% of ELTs presented rates equal to programmed URL). (1) ELTs reduced by postventricular atrial refractory period (PVARP) extension on one cycle: 291 ELTs (87%). ELT rate: 128.5 ± 18.2 bpm. (2) Retrograde block: algorithm operation may induce a retrograde block due to a short atrioventricular delay AVD) applied during the confirmation phase to discriminate an ELT from a stable sinus rhythm. Thirty‐two ELTs (10%) have been reduced and detected on a retrograde block occurrence. (3) Algorithm failure due to an unstable ventriculoatrial conduction time VACT) even at fixed rate or to a retrograde Wenckebach behavior on AVD reduction during the confirmation phase. A total of 10 algorithms failed to detect or confirm an ELT have been recorded 3%). Mean duration: 8.2 ± 4.2 sec, mean ELT rate: 148.9 ± 14.3 bpm. This new fully automatic algorithm has reduced 97% of ELTs, including high rate episodes (100–175 bpm). It allows 1:1 tracking adapted to the needs of the patient, by programming a short PVARP and a physiological AVD.
PR Interval Behavior During Exercise: Implications for Physiological Pacemakers
Authors: LUCERI RICHARD M. , BROWNSTEIN SHELDON L. , VARDEMAN LINDA , GOLDSTEIN SHAWN
Published: October 2007

LUCERI, R., ET AL.: PR Interval Behavior During Exercise: Implications for Physiological Pacemakers. The relationship between heart rate response and the dynamic changes in the PR interval was assessed in 631 patients undergoing routine cardiac exercise tests for a variety of clinical indications. Patients were stratified into four subsets: nonmedicated normals [n = 437), patients on beta‐antagonist agents (n = 118), those on antiarrhythmic agents alone (n = 62) and those with a clinical diagnosis of advanced (New York Heart Association [NYHA] Class 111 or IV) congestive heart failure. All patients were in stable sinus rhythm throughout the test. PR intervals were measured at rest, at mid‐exercise and at peak exercise. Mean PR intervals shortened to a statistically significant degree in most subgroups. This effect was predominantly observed in the earlier stages of exercise. In patients with advanced heart failure, there was no statistically significant shortening of exercise PR intervals later in exercise, demonstrating a parallel with their relatively blunted heart rate response. These changes in exercise PR intervals suggest that implanted pacemaker algorithms may be constructed to maximize hemodynamic benefit in patients requiring physiological pacemakers.
Effect of Short Atrioventricular Delay on Cardiac Output
Authors: RONASZEKI ALADAR , ECTOR HUGO , DENEF BOUDEWIJN , AUBERT ANDRE E. , WERF VAN DE , GEEST HILAIRE DE
Published: October 2007

RONASZEKI, A., ET AL.: Effect of Short Atrioventricular Delay on Cardiac Output. Short atrioventricular (AV) delay modifies late diastolic filling dynamics. The effect of this change on cardiac output [CO) was studied in closed chest, AV blocked canine preparations (N: 10), during AV sequential pacing (80 bpm). CO (thermodilution technique) and transmitral flow velocity (TMFV, pulsed‐wave Doppler) were measured and compared (paired t‐test) on the basis of TMFV pattern, when atrial contraction (A wave) started just after early diastolic transmitral flow deceleration [PR:219 ± 25 ms, mean ± SD) and when A wave occurred at the end of late diastole and shortened due to the next ventricular contraction (PR: 56 ± 11 ms). The short AV delay resulted in 12.0 ± 5.9% decrease of CO, reflecting the interrupted late diastolic atrial transport. Properly timed atrial contraction is necessary for optimal AV sequential pacing.
True Incidence of Pacemaker Syndrome
Authors: HELDMAN DEBRA , MULVIHILL DANIEL , NGUYEN HAROLD , MESSENGER JOHN C. , RYLAARSDAM ARLENE , EVANS KARLA , CASTELLANET MARK J.
Published: October 2007

HELDMAN, D., ET AL.: True Incidence of Pacemaker Syndrome. Although the purported incidence of pacemaker syndrome according to the literature is only 5%–15%, this is based on a series of patients with VVI pacing. Increasing numbers of studies are being reported in which patients prefer the dual chamber mode despite little benefit being demonstrated on objective testing, suggesting that pacemaker syndrome may be more common than is generally reported. This study was designed to evaluate the reported symptoms in a series of patients programmed to both the VVI and one or more dual chamber modes. Forty unselected patients with dual chamber pacemakers were entered into a blind, randomized trial comparing the symptoms associated with VVI pacing to those associated with dual chamber pacing. Patients were randomized to either WI or dual chamber pacing. At the end of 1 week, questionnaires rating 16 different symptoms were completed. Blood pressure, LV function, presence of ventriculoatrial conduction, and ability to override the pacemaker were evaluated. The pacemaker was then programmed to the other mode. Overall, 12 of 16 symptoms were significantly worse in the VVI as compared to dual chamber mode. The most highly significant (p < 0.005) were shortness of breath, dizziness, fatigue, pulsations in the neck or abdomen, cough, and apprehension. Pacemaker syndrome was clinically recognized in 83% of patients paced in the WI mode with 65% of patients experiencing moderate to severe symptoms. There were no readily identified clinical, hemodynamic, or electrophysiological parameters that predicted which patients would develop pacemaker syndrome. Thus, when patients have an opportunity to experience both pacing modes in close proximity to one another, there is a high incidence of pacemaker syndrome in the VVI mode.
Sympathetic Nervous System Response to Dynamic Exercise in Complete AV Block Patients Treated with AV Synchronous Pacing with Fixed AV Delay or with Auto‐AV Delay
Authors: IGAWA OSAMU , TOMOKUNI AKIRA , SAITOH MAKOTO , KITAMURA HIDEYUKI , MIYAKODA HIROYUKI , KOTAKE HIROSHI , MASHIBA HIROTO , ITOH SHIGEKI , KUROGANE HIROYUKI , YOSHIDA YUTAKA
Published: October 2007

IGAWA, O., ET AL.: Sympathetic Nervous System Response to Dynamic Exercise in Complete AV Block Patients Treated with AV Synchronous Pacing with Fixed AV Delay or with Auto‐AV Delay. To investigate the sympathetic nervous system (SNS) responses and circulatory responses to exercise in eight patients (five male and three female) with complete atrioventricular block (CAVB) treated with atrio‐ventricular (AV) synchronous pacing, a symptom‐limited, multistaged treadmill stress test was performed, and plasma norepinephrine (NE) and circulatory parameters were measured at rest, at peak exercise, and in the recovery period. The eight patients were tested using the fixed AV interval (150 or 156 msec). Their exercise tolerance was generally poor. In all measured points, plasma NE levels were significantly higher in the eight study patients than those in the 12 normal subjects (eight male and four female). Systolic blood pressure (SBP) of CAVB patients elevated significantly after exercise compared to that at peak exercise. Heart rate (HR) responses of CAVB patients were characterized by their poor increase at peak exercise. These results suggest that some latent cardiac dysfunction continues in the CAVB patients however satisfactorily the AV synchronous pacing might perform. AV synchronous pacing with three different kinds of auto‐atrioventricular delay (auto‐AVD) was applied to three of the eight patients. In each AVD mode, a treadmill stress test was performed repeatedly according to the same protocol. Plasma NE concentrations under the condition with fixed AVD at peak exercise increased compared to those under the other two conditions with auto‐AVD. These findings suggest that AV synchronous pacing with auto‐AVD WQS better than that with fixed AVD during exercise. Plasma NE response to exercise seems to be a useful indicator for evaluating the condition of patients treated with DDD pacemakers and their adaptation for cardiac function.
An Artificial Neural Network to Localize Atrioventricular Accessory Pathways in Patients Suffering from the Wolff‐Parkinson‐White Syndrome
Authors: DASSEN WILLEM R.M. , MULLENEERS ROB G.A. , DULK KAREL DEN , SMEETS JOEP R.L.M. , CRUZ FERNANDO , PENN OLAF C.K.M. , WELLENS HEIN J.J.
Published: October 2007

DASSEN, W.R.M., ET AL. An Artificial Neural Network to Localize Atrioventricular Accessory Pathways in Patients Suffering from the Wolff‐Parkinson White Syndrome. The electrocardiographic localization of atrioventricular accessory pathways has been extensively described in the literature by a number of well‐known electrophysiologists and surgeons. These descriptions, often represented as decision trees, are useful, but do not apply in all cases. To formalize the process of determining the proper localization, this expert human knowledge could be represented in an expert system. But since reasoning is partly based on the use of heuristic knowledge, and are often not represented in the written description of the human expert, the results will be suboptimal. On the other hand, by using a self‐learning neural network approach, the causal relations between input (polarity of the delta waves) and output (the correct localization) do not have to be defined by the expert. It is derived by the neural network, by analyzing a learning set of cases consisting of the ECG plus the corresponding correct localization. In our set of 60 cases, 2 hours of training were required to learn how to localize all cases correctly. From a control set of 25 cases, 23 were interpreted by the system satisfactorily. Conclusion: the neural network approach can be useful in situations where causal relations between the electrocardiogram and underlying mechanism are partly undefined.
Circadian Rate Variation in Rate‐Adaptive Pacing Systems
Authors: LEE MICHAEL T. , BAKER ROSS
Published: October 2007

LEE, M.T., ET AL.: Circadian Rate Variation in Rate‐Adaptive Pacing Systems. By mimicking the natural rate slowdown during sleep, a pacing system can enhance patient comfort while improving device longevity. A new family of rate‐adaptive pacemakers accomplishes this circadian rate variation by modeling the patient's sleep‐wake cycle using a time‐of‐day clock inside the device. Furthermore, to account for minor variations in the patient's sleep‐wake cycle, sensor data can be used to automatically adapt the starting and stopping points of this change in rate. Using the model, the device begins to gradually reduce the pacing rate beginning one‐half hour before the selected bed time. Similarly, the rate begins to increase one‐half hour before the selected waking time. Sensor data indicating the presence or absence of patient activity are used to adapt the selected bed and wake times, enabling the system to maintain an appropriate schedule despite changes in the patient's actual schedule. The model approximates natural human adaptation times for time zone or work shift changes. This circadian rate adaptation does not preclude the system's rate response to patient activity; even during sleep time the response to moderate or heavy exercise is essentially unchanged.
A Randomized Double‐Blind, Cross‐Over Study of the Linear and Nonlinear Algorithms for the QT Sensing Rate Adaptive Pacemaker
Authors: BAIG M.W. , GREEN A. , WADE G. , KOVANCI E. , CONSTABLE P.D.L. , PERRINS E.J.
Published: October 2007

BAIG, M.W., ET AL.: A Randomized Double‐Blind, Cross‐Over Study of the Linear and Nonlinear Algorithms for the QT Sensing Rate Adaptive Pacemaker. We have compared the pacing rate responses during cardiopulmonary exercise testing in 11 patients (mean 59 years, six female) with implanted QT sensing rate adaptive pacemakers who were randomly programmed to 1‐month periods in the linear and nonlinear algorithms using a double‐blind, cross‐over design. Exercise testing was performed at the end of each month block and symptoms were scored with the MacMaster questionnaire. With exercise, the time to a 10 beats/min increment in rate was significantly less with the nonlinear compared to the linear algorithm (126 sec vs 255 sec, P = 0.02) but there were no significant differences in exercise duration, the peak pacing rate, the peak VO2, the VO2 at the anaerobic threshold or the mean correlation coefficients of the pacing rate VO2 relationship. Rate oscillation occurred in seven patients in the linear algorithm and in two patients in the nonlinear setting. Initial deceleration of the pacing rate at the onset of exercise occurred in seven patients in the linear algorithm and in four patients in the nonlinear setting. The nonlinear algorithm is associated with a faster response time during exercise and fewer instances of rate instability. However, it has not overcome the problem of a dip in the pacing rate at the beginning of exercise. The major difference in the function of the two algorithms is faster initial acceleration with the nonlinear algorithm. This is explained by the significantly higher values of the slope setting at the lower rate limit for the nonlinear versus the linear algorithm (6.3 ms/ms vs 5.1 ms/ms).
Clinical Predictors and Natural History of Atrial Fibrillation in Patients with DDD Pacemakers
Authors: GROSS JAY , MOSER STUART , BENEDEK Z. MICHAEL , ANDREWS CAROLYN , FURMAN SEYMOUR
Published: October 2007

GROSS, J., ET AL.: Clinical Predictors and Natural History of Atrial Fibrillation in Patients with DDD Pacemakers. Effective DDD pacing requires that patients remain free of atrial fibrillation (AF). Four hundred eighty‐nine consecutive patients undergoing initial transvenous DDD implants were reviewed to determine the incidence of postimplant AF in this population and to assess what factors, known at implant, predicted the later development of AF. The variables analyzed included age, sex, indication for implant (dominant SA or AV node disease), history of AF, atrial electrogram characteristics and pacing threshold, and the status of retrograde conduction. Forty‐eight patients (9.8%) developed AF a mean of 23 months postimplant, and 11 of these patients returned to sinus rhythm and were managed once again in DDD for significant periods. A prior history of AF and the presence of dominant sinoatrial disease were far more prevalent in the patients who developed AF (P < 0.001) though the vast majority of patients with these two independent risk factors remained in sinus rhythm through much or all of their follow‐up period. We conclude that the incidence of AF is not of a magnitude to preclude DDD pacing in the vast majority of patients in sinus rhythm at implant.
Comparative Evaluation of Rate Modulated Dual Chamber and VVIR Pacing
Authors: JUTZY ROY V. , FLORIO JOSEPH , ISAEFF DALE M. , MARSA ROBERT J. , BANSAL RAMESH C. , JUTZY KENNETH R. , LEVINE PAUL A. , FEENSTRA LINDA
Published: October 2007

JUTZY, R.V., ET AL.: Comparative Evaluation of Rate Modulated Dual Chamber and VVIR Pacing. While dual chamber pacing is considered superior to VVI pacing at rest, there is a continuing debate as to the relative benefit of AV synchrony versus rate increase with exercise. To evaluate this question and to correlate different methods of evaluation, 14 patients with DDDR pacemakers were studied using serial treadmill exercise test with a CAEP protocol. Patients were exercised in DDD, DDDR, and VVIR modes. Echo‐Doppler cardiac outputs were determined and pulmonary gas exchange was measured during exercise. There was a significant improvement in cardiac output with exercise in the DDDR versus VVIR modes, and in DDDR versus DDD modes in patients with chronotropic incompetence. There were small increases in exercise duration in DDDR versus VVIR modes, and small but consistent increases in VO, at all levels of exercise, though not statistically significant. In this group of patients, DDDR pacing was superior to VVIR pacing, and superior to DDD pacing when chronotropic incompetence was present.
Rate Augmentation and Atrial Arrhythmias in DDDR Pacing
Authors: III WILLIAM H. SPENCER , MARKOWITZ TOBY , ALAGONA PETER
Published: October 2007

SPENCER, W.H., ET AL.: Rate Augmentation and Atrial Arrhythmias in DDDR Pacing. Dual chamber, rate‐modulated pacemakers provide the capability of augmenting the heart rate of patients with chronotropic incompetence but also may cause atrial arrhythmias because of high rate, competitive atrial pacing. We studied ten patients with two consecutive 24‐hour Holter monitors during which they were alternately programmed to either DDD or DDDR pacing in random order. Maximum heart rates (max HR) were measured at every 15‐minute interval during each 24‐hour period. DDDR pacing showed rate augmentation, 80 ± 7 average max HR when compared with DDD pacing, average max HR 76 ± 5. These results were even more striking when waking hours (7 am to 10 pm) were compared: average max HR 86 ± 7 DDDR versus 78 ± 4 average max HR DDD. Several patients showed marked rate augmentation. Seven of ten patients preferred DDDR pacing over DDD pacing. In the entire population, DDDR pacing did not result in an increased number of atrial arrhythmias (1.25 atrial events 124 hour) when compared to DDD pacing (1.75 atrial events/ 24 hour). We conclude that DDDR pacing provides heart rate augmentation during daily life in a clinical population while not resulting in a significant increase in atrial arrhythmias. (PACE, Vol. 13, December, Part 11, 1990)