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PATTERNS OF ATRIOVENTRICULAR-CONDUCTION IN CHILDREN

AMERICAN HEART JOURNAL 1975年第2期90卷 165-171页

作者： PAHLAJANI, DB MILLER, RA SERRATTO, M HEKTOEN INST MED RES CHICAGOIL COOK CTY CHILDRENS HOSP DIV PEDIAT CARDIOL700 S WOOD STCHICAGOIL 60612

In this study, intracardiac electrograms were performed in 20 children—ranging in age from eight months to 18 years and without evidence of conduction disturbances on the scalar electrocardiogram—to determine the normal conduction patterns, response to atrial pacing, and values of refractory periods. Atrial pacing—18 cases—induced a prolongation of AH on increasing heart rates in all; 11 developed Wenckebach block proximal to the bundle of His at the mean pacing rate of 224 per minute ± 45 (1 S.D.). Refractory periods were shorter than in adults. Study of the pattern of A-V conduction revealed three types of response: (1) the atrium was the limiting structure in 11 cases; (2) the delay occurred in the A-V node only in four cases; and (3) the delay occurred both in the A-V node and His-Purkinje system. This response was observed in one case only.

关键词：年龄因素心房功能房室结/生理学希氏束/生理学束支传导阻滞/病理生理学心电描记术心脏导管插入术心脏传导系统/生理学心脏缺损先天性/病理生理学心率心脏起搏器人工反应时间青少年儿童儿童学龄前女(雌)性人类婴儿男(雄)性

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Aging alteration of cardiac vagosympathetic balance assessed through the tone-entropy analysis

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JOURNALS OF GERONTOLOGY SERIES A-BIOLOGICAL SCIENCES AND MEDICAL SCIENCES 1999年第5期54卷 M219-M224页

作者： Oida, E Kannagi, T Moritani, T Yamori, Y Kyoto Univ Grad Sch Human & Environm Studies Appl Physiol Lab Sakyo Ku Kyoto 6068501 Japan Fdn Kyoto Prevent Med Ctr Kyoto Japan

Background. Age-associated alterations of cardiac autonomic functions have been investigated intensively through heart rate variability analyses. However, changes with age in cardiac vagosympathetic balance remain to be elucidated. Methods. We studied 142 male subjects (30-69 yr) at a health care center in Kyoto, Japan. Electrocardiographic data were collected from subjects in a recumbent position for 10 min in the morning. Analysis was done by classifying the subjects into four age groups. In a pharmacological experiment carried out in December 1996, tone was verified to reflect the cardiac vagosympathetic balance, and entropy the total autonomic neural efferent activity. We assessed the heart rate variability through the tone-entropy (T-E) analysis that was described previously. In essence, two indexes, tone and entropy, were defined on a distribution of successive variations of heart period. Results. No significant differences were detected in clinical conditions among the four age groups. Tone increased and entropy decreased significantly with age. The aging process was expressed as a curvilinear path in T-E space. Compared to the pharmacological experiment, it was observed that aging degenerated the heart function from an ordinary to a denervated one. The same aging path was superimposed in the opposite direction on the heart recovery path after dynamic exercise in which cardiac vagosympathetic balance tended toward vagus division, corresponding with restoration of total autonomic activity. Conclusions. An age-related reduction in cardiac autonomic function was consistent with previous reports. The vagosympathetic balance was altered with this reduction: vagal predominance was impaired significantly in proportion to the withdrawal of total cardiac autonomic activity.

关键词：肾上腺素能β受体拮抗剂/药理学衰老/生理学阿托品/药理学自主神经系统/生理学传出通路/生理学心电描记术运动(Exercise)/生理学心脏/生理学心脏传导系统/药物作用心脏传导系统/生理学心率/药物作用心率/生理学神经元传出/生理学抗副交感神经药/药理学普萘洛尔/药理学仰卧位交感神经系统/药物作用交感神经系统/生理学抗交感神经药/药理学迷走神经/药物作用迷走神经/生理学成年人老年人人类男(雄)性中年人

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ANALYSIS OF PACE-MAKER AND REPOLARIZATION CURRENTS IN FROG ATRIAL MUSCLE

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JOURNAL OF PHYSIOLOGY-LONDON 1976年第3期258卷 547-577页

作者： BROWN, HF CLARK, A NOBLE, SJ UNIV OXFORD PHYSIOL LAB OXFORD OX1 3PT ENGLAND

A quantitative analysis of the time-dependent component of outward membrane current in atrial wall trabeculae from Rana catesbeiana and R. ridibunda was carried out using a double sucrose gap technique. Separation of the different components of delayed outward current was hampered by the sigmoid onset of one of the outward current systems ixfast and by the development of K+ accumulation which prevented current activation from reaching a steady state at positive membrane potentials. Semilogarithmic analysis of positive current decay tails recorded immediately following square voltage clamp depolarizations was therefore used to separate the 2 membrane conductance components ixfast and ixslow and the 3rd component, attributable to K+ accumulation, which was almost invariably present in the tails. Inaccuracies in this method of semilogarithmic separation of components caused by visual assessment of the i3 (accumulation) line were minor compared with the large changes in the time constants of ixfast and more especially of ixslow which would result from ignoring the K+ accumulation component. Such semilogarithmic separation of the 3 components of outward current gave separate activation curves for each of the 2 membrane conductance components, ixfast and ixslow. Measurement of total activation curves in which all components of outward current were represented could be made more easily and fairly reliably. The position and shape of these activation curves on the voltage axis closely resembled those obtained by 3 component separation. Such a simplified analysis may reflect the properties of the individual currents sufficiently well for it to be of use in preliminary studies of, for example, drug action. The kinetic properties of the atrial outward currents were investigated over a wide potential range. Because of the presence of K+ accumulation, an indirect method of obtaining the average value of 1/.tau. for outward current decay at negative potentials was employed. Some d

关键词：心房功能心脏传导系统/生理学心率动力学膜电位牛蛙时间因素动物

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Influence of isoproterenol on the accelerated junctional rhythm observed during radiofrequency catheter ablation of atrioventricular nodal slow pathway conduction

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AMERICAN HEART JOURNAL 2001年第4期142卷 664-668页

作者： Matsushita, T Chun, S Sung, RJ Stanford Univ Med Ctr Cardiac Electrophysiol & Arrhythmia Serv Stanford CA 94305 USA

Background Accelerated junctional rhythm (AJR) has been considered as a sensitive but rather nonspecific marker of successful radiofrequency (RF) ablation of slow pathway in patients with atrioventricular nodal reentrant tachycardia (AVNRT). However, AJR also occurs commonly during isoproterenol infusion. We therefore investigated the effect of isoproterenol on the significance of AJR while attempting slow pathway ablation. Methods Forty patients with AVNRT underwent slow pathway ablation. Sixty-nine RF applications accompanied by AJR were observed and were separated into 2 groups: applications performed without (group I, n = 26) and with (group II, n = 43) isoproterenol infusion. The specificity of AJR for successful ablation for each group was calculated. Results The specificity of AJR in groups I and II was 73% (19/26) and 49% (21/43), respectively (P < .05). There was no significant difference between the groups in the atrial electrogram width, atrial/ventricular electrogram amplitude ratio, the time from application onset to AJR emergence, or AJR cycle length. The catheter-tip temperature of AJR emergence was significantly lower (47 degreesC +/- 3 degreesC vs 520 degreesC +/- 30 degreesC, P < .001) and the ratio of junctional beats to total heart beats during RF application was significantly greater (46% +/- 24% vs 33% +/- 18%, P < .05) in group II compared with group I. Conclusions Isoproterenol lowers the threshold of AJR emergence during RF application and thereby lowers the specificity of AJR for successful ablation. Complete washout of isoproterenol may therefore improve the specificity of AJR during RF ablation in patients with AVNRT.

关键词：房室结/生理学房室结/外科学导管消融术/方法心脏/药物作用心脏/生理学心脏传导系统/药物作用心脏传导系统/生理学心率/药物作用心率/生理学异丙肾上腺素/投药和剂量异丙肾上腺素/药理学心肌收缩/药物作用心动过速房室结折返性/病理生理学心动过速房室结折返性/外科学治疗结果青少年成年人老年人女(雌)性人类男(雄)性中年人

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IDENTIFICATION OF PACE-MAKER CURRENT IN FROG ATRIUM

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JOURNAL OF PHYSIOLOGY-LONDON 1976年第3期258卷 521-545页

作者： BROWN, HF CLARK, A NOBLE, SJ UNIV OXFORD PHYSIOL LAB OXFORD OX1 3PT ENGLAND

The nature and interactions of the membrane currents underlying induced pace-maker activity in frog [Rana ridibunda and R. catesbeiana] atrial muscle were investigated using a double sucrose gap technique. The membrane current which controls the speed of the atrial pacemaker depolarization (the pace-maker current, ip), was an outward current activated within the plateau potential range of a normal action potential. The subsequent deactivation of ip at more negative potentials unmasked the depolarizing action of time-independent inward membrane currents so that a pace-maker potential can result. The deactivation of ip over a limited potential range (between about -30 and -60 mV) could be reliably recorded by switching on the voltage clamp during an induced pace-maker depolarization. Investigation of the time and voltage-dependent behavior of ip over a much wider potential range was less straightforward. How ip can be separated from other components of outward current present in the decay tails following square voltage clamp depolarizations was described. The majority of such current decay tails contained 3 components of outward current. It appears that 2 of these components, one of which was ip, are true Hodgkin-Huxley conductance systems chiefly carrying K+. The nature of the 3rd current, which decayed very slowly at moderate membrane potentials (about -40 mV), was discussed, and reasons were briefly given for considering it to result from the accumulation of K+ in extracellular spaces. Preliminary evidence that K+ depletion occurs at potentials negative to the resting potential of the trabeculum was also presented.

关键词：心房功能心脏传导系统/生理学心率动力学膜电位钾/生理学牛蛙动物

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DYNAMIC VAGAL CONTROL OF ATRIAL-VENTRICULAR CONDITION - THEORETICAL AND EXPERIMENTAL STUDIES

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ANNALS OF BIOMEDICAL ENGINEERING 1975年第3期3卷 275-295页

作者： MARTIN, P MT SINAI HOSP DIV INVEST MED CLEVELAND OH 44106 USA CASE WESTERN RESERVE UNIV SCH MED DEPT PHYSIOL CLEVELAND OH USA CASE WESTERN RESERVE UNIV SCH ENGN DEPT BIOENGN CLEVELAND OH USA

The dynamic effects of vagal stimulation on a trial-ventricular (A-V) conduction were studied with paced canine hearts under .beta.-adrenergic blockage. An analog/hybrid computer was used to precisely control the intensity and timing of a vagal stimulus burst given to the cervical vagosympathetic trunk, and to measure the A-V response. On-line digital techniques were used to generate a composite vagal effect curve which is a dynamic representation of nerve-ending process dynamics. The magnitude of the A-V conduction response is critically dependent upon the time in the cardiac cycle at which the vagal stimulus is given. A functionally isomorphic mathematical model, consisting of independent but coupled A-V nodal and vagal-acetylcholine subsystem, were derived and used to simulate and predict the specific characteristics of a variety of vagal effect curves. These predictions were subsequently confirmed under experimental conditions. For example, the peak amplitude of an experimdental vagal effect curve increases with increasing vagal stimulus intensity in the precise nonlinear fashion predicted by the model. Certain changes in the shape characteristics of vagal effect curves are more likely related to changes in the state of the A-V node itself, raher than to changes in the processes which govern the release, diffusion and inactivation of acetylcholine (ACh). It was also demonstrated for the A-V node that the time course of a vagal effect curve need not exactly coincide with the computed time course of ACh concentration at the affected nodal cell membrane, as was assumed previously for the sino-atrial node.

关键词：乙酰胆碱/代谢房室结/代谢房室结/生理学心脏传导系统/生理学心率模型生物学迷走神经/生理学动物狗

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Substance P preferentially inhibits large conductance nicotinic ACh receptor channels in rat intracardiac ganglion neurons

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JOURNAL OF NEUROPHYSIOLOGY 2000年第4期84卷 1961-1970页

作者： Cuevas, J Adams, DJ Univ Queensland Dept Physiol & Pharmacol Brisbane Qld 4072 Australia

The effects of substance P (SP) on nicotinic acetylcholine (ACh)-evoked currents were investigated in parasympathetic neurons dissociated from neonatal rat intracardiac ganglia using standard whole cell, perforated patch, and outside-out recording configurations of the patch-clamp technique. Focal application of SP onto the soma reversibly decreased the peak amplitude of the ACh-evoked current with half-maximal inhibition occurring at 45 mu M and complete block at 300 mu M SP. Whole cell current-voltage (I-V) relationships obtained in the absence and presence of SP indicate that the block of ACh-evoked currents by SP is voltage independent. The rate of decay of ACh-evoked currents was increased sixfold in the presence of SP (100 mu M), suggesting that SP may increase the rate of receptor desensitization. SP-induced inhibition of ACh-evoked currents was observed following cell dialysis and in the presence of either 1 mM 8-Br-cAMP, a membrane-permeant cAMP analogue, 5 mu M H-7, a protein kinase C inhibitor, or 2 mM intracellular AMP-PNP, a nonhydrolyzable ATP analogue. These data suggest that a diffusible cytosolic second messenger is unlikely to mediate SP inhibition of neuronal nicotinic ACh receptor (nAChR) channels. Activation of nAChR channels in outside-out membrane patches by either ACh (3 mu M) or cytisine (3 mu M) indicates the presence of at least three distinct conductances (20, 35, and 47 pS) in rat intracardiac neurons. In the presence of 3 mu M SP, the large conductance nAChR channels are preferentially inhibited. The open probabilities of the large conductance classes activated by either ACh or cytisine were reversibly decreased by 10- to 30-fold in the presence of SP. The single-channel conductances were unchanged, and mean apparent channel open times for the large conductance nAChR channels only were slightly decreased by SP. Given that individual parasympathetic neurons of rat intracardiac ganglia express a heterogeneous population of nAChR subunits

关键词：乙酰胆碱/药理学导电性神经节副交感/细胞学神经节副交感/代谢神经节副交感/生理学心脏传导系统/细胞学心脏传导系统/代谢心脏传导系统/生理学神经元/代谢神经元/生理学受体烟碱/药物作用受体烟碱/生理学第二信使系统/生理学 P物质/药理学动物大鼠

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A method for determining baroreflex-mediated sympathetic and parasympathetic control of the heart in pregnant and non-pregnant sheep

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JOURNAL OF PHYSIOLOGY-LONDON 1999年第2期515卷 555-566页

作者： Lumbers, ER Yu, ZY Univ New S Wales Sch Physiol & Pharmacol Sydney NSW 2052 Australia

1. The cardiac baroreflex was measured in four non-pregnant and six pregnant ewes before and during beta-adrenoreceptor blockade with propranolol and before and during vagal blockade with atropine. Arterial pressure was raised by phenylephrine and lowered by sodium nitroprusside. The relationships between mean arterial pressure (MAP) and heart rate (HR), between MAP and heart rate variability (HRV) measured as the coefficient of variation (c.v.) of the mean pulse interval (PI), and between MAP and HRV measured by power spectral analysis were determined. 2. The MAP-MR relationship showed that in pregnant ewes the gain of the cardiac baroreflex was reduced when compared with non-pregnant ewes. Threshold and saturation pressures mere higher, maximum achievable HR was lower and there was a decrease in the operating range. 3. V-shaped relationships were obtained between MAP and HRV (measured as the c.v of PI) and between MAP and power spectral density in the frequency range 0.04-0.08 Hz. Using selective autonomic blockade the negative, or downward, slope of the V shape was shown to be a measure of baroreceptor-induced, sympathetically mediated effects on HRV. The upward, or positive, slope of the V shape was a measure of baroreceptor-induced, vagally mediated effects. Similar results were also obtained from the cardiac power spectrum, but it was less sensitive. The MAP at which the two slopes intersected was the same as the resting MAP. 4. In pregnant ewes, the slope of the downward limb of the V-shaped relationship between HRV (when measured as the c.v. of PI) and MAP was less than in non-pregnant ewes. 5. The relationship between MAP and the coefficient of variation of the mean pulse interval can therefore be used to measure the degree to which baroreceptor-induced sympathetic and parasympathetic activity affects the heart. 6. The resting MAP is the pressure at which the net effect of these sympathetic and parasympathetic influences on the heart is at a minimum. Studie

关键词：压力感受器反射/生理学血压/生理学心脏传导系统/生理学心率/生理学方法副交感神经系统/生理学妊娠动物/生理学参考值交感神经系统/生理学动物女(雌)性妊娠

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Cardiac biomagnetic source estimation with a heart-torso model and a trained neural network

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PHYSICS IN MEDICINE AND BIOLOGY 1999年第10期44卷 2551-2563页

作者： Ramon, C Casem, M Univ Washington Dept Elect Engn Seattle WA 98195 USA

The intensity of the cardiac sources for normal adult subjects was estimated from given magnetic field profiles with a trained neural network based on the relationship of the electrical activity of the heart to the cardiac magnetic fields. The input for training the neural network consisted of the magnetic field profiles above the torso during the heartbeat. The outputs were the dipole intensities which produced those magnetic field profiles. A back-propagating algorithm with bias and momentum was utilized for training. The measured and simulated torso magnetic field profiles and magnetocardiograms were used for training the neural network. Estimation of the dipole intensities was performed for unknown magnetic field profiles with the trained neural network. The estimated cardiac dipole intensities were reasonably close to the true dipole intensities. These results show the feasibility of the estimation of cardiac dipole intensities with a trained neural network under a very restricted forward model of the cardiac magnetic fields. Generalization of the results to cover a large population base could be difficult because the activation isochrones are different from subject to subject.

关键词：计算机模拟心脏/生理学心脏/辐射效应心脏传导系统/生理学心脏功能试验磁力学神经网络(计算机) 神经元/生理学成年人人类

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Transgenic mice with cardiac-specific expression of activating transcription factor 3, a stress-inducible gene, have conduction abnormalities and contractile dysfunction

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AMERICAN JOURNAL OF PATHOLOGY 2001年第2期159卷 639-650页

作者： Okamoto, Y Chaves, A Chen, JC Kelley, R Jones, K Weed, HG Gardner, KL Gangi, L Yamaguchi, M Klomkleaw, W Nakayama, T Hamlin, RL Carnes, C Altschuld, R Bauer, J Hai, T Ohio State Univ Dept Mol & Cellular Biochem Columbus OH 43210 USA Ohio State Univ Neurobiotechnol Ctr Columbus OH 43210 USA Ohio State Univ Dept Pharm Columbus OH 43210 USA Ohio State Univ Ohio State Biochem Program Columbus OH 43210 USA Ohio State Univ Dept Med Columbus OH 43210 USA Ohio State Univ Dept Vet Biosci Columbus OH 43210 USA NCI Ctr Adv Technol Gaithersburg MD USA Univ Cincinnati Dept Pharmacol & Cell Biophys Cincinnati OH USA

Activating transcription factor 3 (ATF3) is a member of the CREB/ATF family of transcription factors. Previously, we demonstrated that the expression of the ATF3 gene is induced by many stress signals. In this report, we demonstrate that expression of ATF3 is induced by cardiac ischemia coupled with reperfusion (ischemia-reperfusion) in both cultured cells and an animal model. Transgenic mice expressing ATF3 under the control of the alpha -myosin heavy chain promoter have atrial enlargement, and atrial and ventricular hypertrophy. Microscopic examination showed myocyte degeneration and fibrosis. Functionally, the transgenic heart has reduced contractility and aberrant conduction. Interestingly, expression of sorcin, a gene whose product inhibits the release of calcium from sarcoplasmic reticulum, is increased in these transgenic hearts. Taken together, our results indicate that expression of ATF3, a stress-inducible gene, in the heart leads to altered gene expression and impaired cardiac function.

关键词：转录激活因子3 钙结合蛋白质类/遗传学心脏扩大/遗传学心脏扩大/病理学心脏扩大/病理生理学细胞培养的疾病模型动物基因表达调控心脏传导系统/生理学小鼠转基因心肌收缩/遗传学心肌收缩/生理学心肌缺血/遗传学心肌缺血/病理学心肌缺血/病理生理学心肌再灌注心肌/病理学肌球蛋白重链/遗传学磷蛋白类/遗传学启动区遗传大鼠 Sprague-Dawley 转录因子/遗传学转录因子/生理学动物人类男(雄)性小鼠大鼠

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