Search PubMed⌕ Search

Biomedical subjects

M Hayano

Publications and source records attributed to M Hayano.

At least 37 records · Page 2Linked to original sources
PubMed1998

Atrial conduction curves in patients with and without atrial fibrillation.

In order to quantify underlying atrial conduction properties in patients with atrial fibrillation (AF) using clinical electrophysiology techniques, atrial conduction curves relating intra-atrial conduction times to extrastimulus prematurities during programmed atrial stimulation were drawn. Based on the presence or absence of AF episodes, 95 subjects were divided into 2 groups: control (n=42); and AF (n=53). During programmed stimulation introduced from the right atrial appendage, an atrial conduction curve was drawn for each patient. For most of the control subjects, when the extrastimulus prematurity was increased by 10-ms steps, the intra-atrial conduction times also increased gradually; the maximum stepwise prolongation in intra-atrial conduction time was 11.0+/-3.4 msec. For patients with AF, a 10-msec increase in extrastimulus prematurity often produced a sudden marked prolongation in the intra-atrial conduction time; the maximum stepwise prolongation of intra-atrial conduction time was 21.4+/-5.9 msec. In contrast to the gradual atrial conduction curves recorded in control subjects, the sudden prolongation of intra-atrial conduction time was remarkable on the curves obtained in patients with AF. Statistical significance was clearly established (p<0.0001). This difference could be related to differences in the underlying conduction properties in patients with and without AF.

Adult↗
PubMed1998

[Abnormalities of electrocardiographic P wave morphology and the relationship to electrophysiological parameters of the atrium in patients with idiopathic paroxysmal atrial fibrillation].

In 39 patients with idiopathic paroxysmal atrial fibrillation (PAF group), the incidence of the abnormal P wave morphology (prolonged P wave and mitral P in lead II and increased P terminal force in lead V1: PTF V1) was examined, and the relationships to the electrophysiologic findings of the atrial muscle were investigated. The control group consisted of 42 patients with various cardiac arrhythmias other than sick sinus syndrome. P wave duration was significantly longer in the PAF group than in the control group (112 +/- 12 vs 98 +/- 10 msec, p < 0.0001). PTF V1 was greater in the PAF group than in the control group (0.051 +/- 0.018 vs 0.028 +/- 0.010 msec, p < 0.0001). P mitrale occurred in only 5 patients (12%) in the control group as compared to 25 patients in the PAF group (64%, p < 0.0001). The longest duration of the right atrial electrograms was longer in the PAF group than in the control group (101 +/- 17 vs 85 +/- 10 msec, p < 0.0001), as was the maximal number of the fragmented deflections (8.0 +/- 2.5 vs 5.8 +/- 1.4, p < 0.0001). Repetitive atrial firing zone and also fragmented atrial activity zone were longer in the PAF group than in the control group (34 +/- 24 vs 12 +/- 19 msec, p < 0.02 and 47 +/- 27 vs 24 +/- 19 msec, p < 0.001, respectively). Interatrial conduction delay zone was longer in the PAF group than in the control group (55 +/- 25 vs 38 +/- 18 msec, p < 0.001). P wave duration and PTF V1 had significant and/or borderline correlations with the longest duration of the right atrial electrocardiograms (r = 0.75, p < 0.0001 and r = 0.68, p < 0.0001, respectively), and the maximal number of its fragmented defections (r = 0.50, p < 0.002 and r = 0.40, p < 0.05, respectively). Furthermore, P wave duration had a correlation with the repetitive atrial firing zone (r = 0.55, p < 0.01). Prolonged P wave duration and increased PTF V1 are electrocardiographic indicators for the coexistence of electrophysiologic abnormalities in patients with idiopathic paroxysmal atrial fibrillation.

Adult↗
PubMed1997

Melanotic cerebral astrocytoma: case report and literature review.

We describe the case of 47-year-old man with a cystic, melanotic temporal lobe astrocytoma who had a history of complex partial seizures. The tumor mass was made up of two histologically different regions: one consisted of spindle-shaped and pleomorphic cells often with foamy or vacuolated cytoplasm, while the other consisted of fairly uniform spindle-shaped cells, many of which contained dark-brown intracytoplasmic pigment. Desmoplasia was also noted in the latter region of the tumor. No features suggestive of malignancy, such as mitotic figures, necrotic foci or endothelial vascular proliferation, were observed throughout the tumor. Immunohistochemically, the tumor cells in both regions were positive for glial fibrillary acidic protein. Ultrastructural examination of the pigmented region showed the presence of melanosomal melanin in the tumor cells. Apart from the partial pigmentation, the entire histological picture resembled a pleomorphic xanthoastrocytoma. To our knowledge, only two cases of similar melanotic astrocytic tumors have been described previously. Interestingly, the astrocytic tumors in both of these patients were also clinically associated with epilepsy, were located in the temporal lobe, and were histologically benign.

Astrocytoma↗
PubMed1997

Evidence of three clinical subgroups in patients with dual atrioventricular nodal pathways.

We attempted to test the hypothesis that dual atrioventricular (A-V) nodal pathways with second-degree atrioventricular block (2nd A-V block) present as a different clinical entity from those with A-V nodal reentranttachycardia (AVNRT). By evaluation with Holter monitoring (2.9 +/- 2.5 recordings/patient) and 12-lead electrocardiogram (11.9 +/- 11.6), 177 patients with dual A-V nodal pathways could be divided into three subgroups. Thirty-two patients had 2nd A-V block only (2nd A-V block group), 57 had AVNRT only (AVNRT group), 88 had neither 2nd A-V block nor AVNRT (silent group), and none had 2nd A-V block and AVNRT both. Electrophysiologic studies showed that the atrio-His interval was significantly greater (P < 0.0001) and the maximal 1:1 atrioventricular conduction rate was lower (P < 0.0001) in the 2nd A-V block group than in the other two groups. These differences were nullified after the administration of atropine. These results suggest that patients with dual A-V nodal pathways can be classified into three clinical subgroups based on the presence of either 2nd A-V block or AVNRT. We suggest also that patients of the 2nd A-V block group may have a more augmented vagal tone on the A-V node than the other two groups.

Adolescent↗
PubMed1996

[Signal transduction system in cardiac cells].

The electrical excitation and conduction in the heart is due to ionic events via ion channels and gap junctions. Function of these channels and gap junctions is regulated by intracellular milieu, which is regulated by many kinds of receptors through intracellular second messengers i.e.; GTP binding proteins, protein kinases, Ca2+ concentrations, H+ concentration, cyclic nucleotides and triphosphate nucleotides. In this paper, we focus on signal transduction systems in cardiac myocytes. Subsequently, some of interactions between signal transduction systems are introduced.

Cyclic AMP↗
PubMed1995

Significance of elevated urinary human intestinal alkaline phosphatase in Japanese people exposed to environmental cadmium.

Urinary human intestinal alkaline phosphatase (IAP), beta 2-microglobulin (beta 2-MG) and N-acetyl-beta-D-glucosaminidase (NAG) were analyzed in 40 Japanese environmental-cadmium (Cd)-exposed and 40 non-exposed subjects to evaluate early biological markers for Cd-induced renal damage. All urinary indicators were significantly higher in the Cd-exposed subjects than non-exposed subjects. A fourth-order function was fitted for the relationship between beta 2-MG and IAP or NAG. The beta 2-MG concentration corresponding to the inflexion point for IAP was smaller than that for NAG. This result may support the contention that the cells containing IAP are damaged earlier than those containing NAG, and that IAP is a useful marker for detecting renal tubular dysfunction in people moderately exposed to Cd. However, in the stage of severe renal damage, the combination of IAP and beta 2-MG is considered to be more useful.

Acetylglucosaminidase↗
PubMed1995

Electrophysiological effects of MS-551 in humans: a class III antiarrhythmic agent.

To investigate the clinical effects of MS-551, a Class III antiarrhythmic agent, 11 patients underwent electrophysiological study. MS-551 was given intravenously as an initial dose of 0.2 or 0.3 mg/kg for 5 minutes followed by the continuous infusion at 0.2 or 0.3 mg/kg for 30 minutes, respectively, in all patients. The rate corrected QT interval increased significantly from 3 minutes after the beginning of MS-551 infusion. The sinus heart rate decreased significantly by 8% at 10 minutes after the drug administration (P < 0.025). Mean PR and QRS intervals, and blood pressure were not significantly affected by the drug. Mean PA, AH, and HV intervals during sinus rhythm were also not affected. The effective refractory periods (ERPs) of the atrium and ventricle were significantly prolonged by 13% from 202 +/- 24 ms to 231 +/- 26 ms (P < 0.0005), and by 7% from 238 +/- 11 ms to 257 +/- 13 ms (P < 0.002), respectively, by MS-551. The ERP of the atrioventricular node and sinoatrial nodal recovery time were not changed significantly by the drug. This is a report of the effects of MS-551 in humans. This agent could be useful for treatment of tachyarrhythmias by prolongation of ERPs of the atrium and ventricle without significant variations of blood pressure and intracardiac conduction times. It is noteworthy that MS-551 slightly but significantly decreased heart rate.

Aged↗
PubMed1995

Radiofrequency catheter ablation for atrioventricular node reentry tachycardia with multiple slow atrioventricular node pathways.

Catheter ablation was attempted in 2 patients with atrioventricular node reentry tachycardia which showed fast, intermediate and slow anterograde atrioventricular node pathways. Radiofrequency currents were applied within a restricted area of the tricuspid annulus between the His bundle and the ostium of the coronary sinus where presumed slow pathway potentials were identified. Elimination of both the intermediate and the slow pathways, with preservation of anterograde and retrograde fast pathway conduction, was achieved in both patients.

Aged↗
PubMed1995

Effects of aprindine on electrophysiological properties of the atrial muscle in man.

The effects of aprindine on atrial vulnerability were studied in 11 patients; 9 with paroxysmal atrial fibrillation (PAF), and 2 with Wolff-Parkinson-White syndrome, aged 19 to 69 (55.9 +/- 16.5; mean +/- SD). Before and 10 min after the intravenous injection of aprindine (1.5 mg/kg), programmed extrastimulation was performed from the right atrial appendage. Atrial vulnerability was assessed by evaluating the repetitive atrial firing zone (RAFZ), conduction delay zone (CDZ), maximum conduction delay (Max. CD) and fragmented atrial activity zone (FAAZ). After the injection, the duration of the P wave and QTc interval was significantly prolonged without any change in blood pressure or heart rate. RAF was observed in 8 patients under control conditions. However, after the injection of aprindine, the RAFZ completely disappeared in 2 patients, was narrowed in 4, and became wider in 1. AF was induced in the remaining patient. The zone significantly reduced (p < 0.01) without any change in CDZ or Max. CD. While FAA was observed in 5 patients under control conditions, it completely disappeared in 2 patients, was narrowed in 1, and did not change in the remaining 7 after the injection of aprindine. In patients whose RAFZ narrowed after administration of aprindine, the wavelength, as determined from the atrial effective refractory period and conduction velocity, was augmented. These results indicate that aprindine suppresses atrial vulnerability with an augmentation of the wavelength. However aprindine exaggerated atrial vulnerability in some patients, such that atrial fibrillation was induced.

Action Potentials↗
PubMed1995

Effects of degraded schizophyllans on regeneration of protoplast cells of Saccharomyces cerevisiae.

Schizophyllan was heated at 100 degrees C in 85% dimethyl sulfoxide (DMSO) containing 0.01 M H2SO4 for various times, and fractionated by gel-permeation chromatography. Molecular weights (M(r)) of the depolymerized products thus obtained were measured in water and DMSO by GPC-LALLS to estimate their conformations in water. The products with triple helical structure stimulated regeneration of Saccharomyces cerevisiae protoplast cells, while those of single chain conformation were totally inactive.

Hydrolysis↗
PubMed1994

Electrophysiologic demonstration of anterograde fast and slow pathways within the His bundle in patients with normal intraventricular conduction.

Electrophysiological evidence of functional longitudinal dissociation has been shown in different structures of the normal conduction system of the heart and in anomalous atrioventricular (AV) pathways. The typical sudden fast-to-slow jump phenomenon, which is commonly observed in patients with dual AV nodal pathways, has not been demonstrated so far within the normal His bundle. Herein we report unusual electrophysiological properties of the His bundle in two patients with normal intraventricular conduction. Of 86 patients with discontinuous anterograde AV function curves, programmed atrial stimulation revealed dual anterograde His bundle pathways in only 2 (2.3%) patients. Extrastimuli introduced at critically timed coupling intervals produced a sudden marked increase in H2-V2 interval suggesting failure of fast pathway with conduction proceeding through a slower pathway with shorter refractory period. With further decreasing coupling intervals, the second H2-V2 curve showed decremental conduction which allowed a type II gap phenomenon in the right bundle branch to occur in one of the patients. No echo beats were observed. These results provide the first electrophysiological demonstration, in patients with normal intraventricular conduction, of anterograde failure of a fast His bundle pathway with subsequent conduction through a slow His bundle pathway. His bundle duality was manifested by dual conduction times and refractory periods. These observations further expand our knowledge on the electrophysiologic properties of the His bundle.

Atrial Fibrillation↗
PubMed1994

Evidence of quadruple anterograde atrioventricular nodal pathways in a patient with atrioventricular node reentry.

Functional longitudinal dissociation of the atrioventricular (AV) node exhibiting two discrete discontinuities in AV nodal conduction curves suggestive of triple AV nodal pathways has been described. The authors report here unusual electrophysiologic properties of the AV node in a patient with documented episodes of paroxysmal supraventricular tachycardia. Programmed atrial extrastimuli introduced at A1-A2 coupling intervals of 390 ms with a driven cycle length of 500 ms produced a sudden marked increase of 75 ms at the A2-H2 intervals suggesting failure of the fast pathway with conduction proceeding through a slower pathway with a shorter refractory period. With further decreasing coupling intervals, a second sudden jump of 70 ms and a third one of 150 ms occurred at A1-A2 coupling intervals of 330 and 290 ms, respectively. Beyond the first sudden jump, atrial echoes occurred when sufficiently slow pathway delay permitted recovery of the fast pathway for retrograde conduction. The atrial echo zone was 170 ms. These electrophysiologic demonstrations of reentry within the AV node in a patient with clinically documented supraventricular tachycardia and the existence of four ranges of AH conduction times and refractory periods strongly suggest the presence of quadruple anterograde AV nodal pathways and a variety of potential loops available for the development of sustained AV nodal reentrant tachycardia.

Adult↗
PubMed1994

Possible role of supernormal atrial conduction in the genesis of atrial fibrillation in patients with idiopathic paroxysmal atrial fibrillation.

OBJECTIVE: The occurrence of supernormal excitability and conduction in the atrium has been attributed to the internodal pathways in several animal experiments. However, little is known about the role of supernormal atrial conduction (SNC) in the genesis of arrhythmias. The specific aim of this study was to evaluate prospectively the relationship between SNC, atrial conduction defects and atrial fibrillation in patients with idiopathic paroxysmal atrial fibrillation. METHODS: Programmed atrial stimulation was performed in 38 control patients (group 1), and 21 patients with idiopathic paroxysmal atrial fibrillation (group 2) to assess some determinants of atrial conduction defects, SNC, and atrial fibrillation inducibility. RESULTS: The mean P-wave duration was 99 +/- 8 ms in group 1, and 110 +/- 12 ms in group 2; p < 0.001. The maximum interatrial conduction delay was 36 +/- 40 ms in group 1, and 56 +/- 21 ms in group 2; p < 0.005. Supernormal atrial conduction was observed in 27 (71 percent) patients of group 1, and in 5 (24 percent) of group 2; p < 0.0003. The SNC zone was 70 +/- 29 ms in group 1, and 16 +/- 31 ms in group 2; p < 0.0001. The maximum decrease in conduction time during the period of SNC was 12 +/- 4 ms in group 1 and 3 +/- 6 ms in group 2; p < 0.0005. The SNC zone showed a significant inverse correlation with the P-wave duration (r = -0.53; p < 0.0005), and with the maximum conduction delay (r = -0.38; p < 0.005). CONCLUSIONS: Patients with idiopathic paroxysmal atrial fibrillation have a significantly decreased incidence of SNC than controls. There is an inverse relation between the atrial conduction defects and the SNC. The association of the absence of SNC with defects in atrial conduction may play some role in the development of atrial fibrillation in patients with idiopathic paroxysmal atrial fibrillation.

Adult↗