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H Yamanari

Publications and source records attributed to H Yamanari.

At least 19 recordsLinked to original sources
PubMed2000

Nicorandil attenuates both temporal and spatial repolarization alternans.

T-wave alternans (TWA) on the electrocardiogram have been frequently associated with long QT syndrome (LQTS) and abrupt rate change. The present study investigated the effect of the potassium channel opener nicorandil on the repolarization alternans at the endocardium and the epicardium in the left ventricle. Electrocardiogram and transmural monophasic action potentials from the endocardium and the epicardium were simultaneously recorded in Langendorff-perfused guinea pig hearts. The hearts were paced at a basic cycle length (BCL) of 240 ms and the cycle length (CL) was abruptly shortened to 170 ms to induce repolarization alternans. Disopyramide and nicorandil were used to increase or attenuate repolarization alternans, respectively. Repolarization alternans were numerically expressed as the sum of the absolute difference between consecutive monophasic action potential durations at 90% repolarization (MAPD90) in the first 10 beats. In the control hearts, the MAPD90 alternans were 78.6 +/- 14.9 ms at the endocardium, and 49.8 +/- 58 ms at the epicardium (P = .03 endocardium vs epicardium). Disopyramide (2 microg/mL) increased the MAPD90 alternans to 186.6 +/- 30.6 ms at the endocardium and 116.4 +/- 16.5 ms at the epicardium, and enhanced the difference of repolarization alternans between the endocardium and the epicardium (transmural dispersion) from 28.8 +/- 11.3 ms to 70.2 +/- 18.7 ms (P = .02 vs controls). Nicorandil (400 ng/mL) suppressed the MAPD90 alternans to 79.6 +/- 16.3 ms at the endocardium and 56.0 +/- 11.8 ms at the epicardium, and attenuated the transmural dispersion to 23.6 +/- 6.0 ms (P = .02 vs disopyramide-administrated hearts). Our results suggest that nicorandil attenuates both temporal (beat-to-beat) and spatial (between the endocardium and the epicardium) repolarization alternans induced by the combination of cycle length changes and disopyramide administration.

Animals↗
PubMed2000

Effects of cardiac sympathetic innervation on regional wall motion abnormality in patients with long QT syndrome.

AIM: To assess the spatial relation between regional cardiac sympathetic innervation and regional ventricular repolarisation indicated by ventricular wall motion abnormality in patients with congenital long QT syndrome. DESIGN: Regional percentage uptake and washout rate of (123)I metaiodobenzylguanidine (MIBG) were measured to assess cardiac sympathetic innervation in septum, anterior wall, lateral wall, and posterior wall. Left ventricular short axis images on echocardiography were digitised to reconstruct digitised M mode echocardiograms, from which left ventricular wall thickness curves were obtained. The wall thickening time (ThT) was defined as the period in which the instantaneous wall thickness exceeded 90% of the maximum wall thickness. The ThT was measured from the ventricular wall thickness curve at the same segments where regional percentage uptake and washout rate of (123)I MIBG were measured. PATIENTS: Seven patients with long QT syndrome. RESULTS: The regional washout rate (mean (SD)) of (123)I MIBG in patients with long QT syndrome was greater in the segments with decreased percentage uptake of (123)I MIBG than in those without (17.4 (10.6)% v 9.7 (16.5)%, p < 0. 03). ThT in segments both with and without decreased percentage uptake of (123)I MIBG was longer than in control subjects (p < 0. 0001). ThT was longer in the segments with decreased percentage uptake of (123)I MIBG than in those without (199 (70) ms v 150 (66) ms, p = 0.0018). CONCLUSIONS: Activation of regional cardiac sympathetic terminals is likely to participate in additional regional prolongation of ventricular repolarisation in patients with long QT syndrome.

3-Iodobenzylguanidine↗
PubMed2000

Involvement of Ca(2+) in antiarrhythmic effect of ischemic preconditioning in isolated rat heart.

We investigated the relationship between the effects of ischemic preconditioning (IPC) and Ca(2+) preconditioning (CPC) on reperfusion-induced arrhythmias. In the control group (noPC), Langendorff-perfused rat hearts were subjected to 5-min zero-flow global ischemia (I) followed by 15-min reperfusion (I/R). In ischemic preconditioning groups (IPC), the hearts were subjected to three cycles of 3-min global ischemia and 5-min reperfusion. In the CPC group, the hearts were exposed to three cycles of 3-min perfusion of higher Ca(2+) (2.3 mmol/l Ca(2+)) followed by 5-min perfusion of normal 1.3 mmol/l Ca(2+), and the hearts were then subjected to I/R. Verapamil was administered in several hearts of the IPC group (VR+IPC). Ventricular arrhythmias upon reperfusion were less frequently seen in the IPC and CPC groups than in the noPC and VR+IPC groups. IPC and CPC could attenuate conduction delay and enhance shortening of the monophasic action potential duration during ischemia. The ventricular fibrillation threshold measured at 1-min reperfusion was significantly higher in the IPC and CPC groups than in the noPC and VR+IPC groups. Verapamil completely abolished the salutary effects of IPC. These results demonstrate that Ca(2+) plays an important role in the antiarrhythmic effect of IPC during reperfusion.

Animals↗
PubMed1999

Attenuation of conduction delay by ischemic preconditioning reduces ischemia-induced ventricular arrhythmias.

Ischemic preconditioning has been acknowledged as a powerful method of decreasing ischemic injury. However, the antiarrhythmic mechanism of ischemic preconditioning during ischemia is unclear. We studied the effects of ischemic preconditioning on arrhythmias and cardiac electrophysiology during ischemia in Langendorff rat hearts (n = 44). In the non-preconditioned group (PC(-); n = 24), the hearts underwent 5-min zero-flow global ischemia without any prior ischemic preconditioning. In the preconditioned group (PC(+); n = 20), the hearts were preconditioned by three cycles of 3-min zero-flow global ischemia and 5-min reperfusion before undergoing 5-min global ischemia. Ischemic preconditioning reduced the incidence of ischemia-induced arrhythmias (PC(-); 38.9%, PC(+): 8.3%, p < 0.05), shortened monophasic action potential duration (MAPD, P < 0.05), attenuated conduction delay (conduction time; PC(-): 234.2%, PC(+): 173.4%, P < 0.05) and increased the ventricular fibrillation threshold. Although the shortening of MAPD in PC(-) hearts was not influenced by the presence or absence of arrhythmias, conduction time prolongation at 3-min was more obvious in PC(-) hearts with arrhythmia than in PC(-) hearts without arrhythmia (PC(-) with arrhythmia: 220.2%, PC(-) without arrhythmia: 190.7%, P < 0.05). We concluded that ischemic preconditioning could protect the rat hearts from ischemia-induced arrhythmias and postulated that attenuation of conduction delay during ischemia might be an important factor in the antiarrhythmic action of ischemic preconditioning.

Action Potentials↗
PubMed1999

[Myoglobin].

Explore the source record for details and available documents.

Humans↗
PubMed1998

Hormonal characteristics of primary aldosteronism due to unilateral adrenal hyperplasia.

A case of unilateral adrenocortical hyperplasia is presented. A 46-year-old woman with a 7-year history of hypertension and a 1-year-history of hypokalemia was diagnosed with primary aldosteronism. Computed tomography, magnetic resonance imaging, venous sampling and adosterol scintigraphy exhibited a functioning left adrenal mass. The plasma aldosterone concentration increased markedly when furosemide with upright posture and either captopril or adrenocorticotropin were administered. Plasma renin activity was suppressed below the detectable range. Aldosterone secretion displayed a circadian rhythm and was not suppressed by dexamethasone administration. The resected left adrenal mass was pathologically diagnosed as adrenocortical nodular hyperplasia. Unilateral adrenal hyperplasia involving the zona glomerulosa rarely has been reported, with varying and incompletely characterized hormonal characteristics. This case report and literature review suggest unilateral adrenal hyperplasia as a rare cause of hyperaldosteronism with characteristics intermediate between idiopathic hyperaldosteronism and aldosterone-producing adrenocortical adenoma, resembling the functional features of the adenoma more closely.

Adrenal Cortex↗
PubMed1998

Dispersion of regional wall motion abnormality in patients with long QT syndrome.

OBJECTIVE: To examine the left ventricular regional wall motion abnormality and to evaluate dispersion of this abnormality in patients with long QT syndrome. DESIGN: Left ventricular short axis images at basal and middle levels were recorded on videotape and digitised to reconstruct digitised M mode echocardiograms, from which left ventricular wall thickness curves were obtained. The wall thickening time (ThT) was defined as the period in which the instantaneous wall thickness exceeded 90% of the maximum wall thickness. ThT was measured at three segments in each of the septal and free wall sides of the left ventricle, a total of 12 segments. To examine the mechanical dispersion of the left ventricle, the difference between the maximum and minimum ThT of 12 segments in each subject was obtained. PATIENTS: Eight patients with congenital long QT syndrome (averaged QTc interval (SD) 509 (27) ms1/2) and 10 control subjects (QTc interval 397 (26) ms1/2) were examined. RESULTS: The averaged ThT values of the 12 segments pooled form all subjects were correlated with the QT intervals (r = 0.72, p < 0.005). Thus the averaged ThT in the long QT syndrome patients was longer than in the control subjects (p < 0.005). The segmental variation of ThT in the patients was greater than in the control subjects (p < 0.001). The dispersion of ThT in the patients was therefore larger than in control subjects (p < 0.005). However, the pattern of ThT variation in the patients varied according to the individual subject. CONCLUSIONS: There is not only electrical but also mechanical dispersion in the left ventricle of long QT syndrome patients. Regional assessment of ventricular wall motion may allow quantification of the spatial variation of wall motion abnormality.

Adolescent↗
PubMed1998

Relationship between electrocardiographic features and distribution of hypertrophy in patients with hypertrophic cardiomyopathy.

To evaluate the relationship between the distribution of hypertrophy and the electrocardiographic findings in patients with hypertrophic cardiomyopathy (HCM), 54 HCM patients were studied using magnetic resonance imaging. The patients were divided into 4 groups according to hypertrophic patterns: (i) hypertrophy only at the apex (group I, n=12); (ii) hypertrophy in both the apex and base (group II, n=20); (iii) hypertrophy only at the base with asymmetric septal hypertrophy (ASH) (group IIIa, n=17); and (iv) hypertrophy only at the base without ASH (group IIIb, n=5). Abnormal Q waves in leads II, III and aVF were found in 1/12, 3/20, 10/17 and 0/5, respectively, and in leads I and aVL they were found in 1/12, 8/20, 4/17 and 1/5, respectively. The largest negative T waves (mm) were found in group I (group I vs group II vs group IIIa vs group IIIb: 15.2+/-5.3, 8.2+/-6.1, 1.6+/-2.0, 0.8+/-1.3, respectively). The largest positive T waves (mm) were identified in group IIIb (3.8+/-3.0, 6.8+/-3.2, 5.8+/-3.6, 9.3+/-2.1, respectively). The presence of abnormal Q waves reflected regional hypertrophy in HCM patients but the configuration of T waves represented the difference in the localization of hypertrophy between the basal and apical segments.

Adrenergic beta-Antagonists↗
PubMed1997

P-selectin expression in a metastatic pancreatic tumor cell line (SUIT-2).

The human pancreatic tumor cell line SUIT-2 was derived from a metastatic lesion in the liver of a patient with pancreatic adenocarcinoma. SUIT-2 and clonal cell lines derived from it show spontaneous metastasis to lung and regional lymph nodes from s.c. nude mouse xenografts and were found to express P-selectin mRNA and protein. Surface expression of P-selectin protein was increased by exposure of the pancreatic tumor cells to thrombin, oxygen radicals, and trypsin, suggesting that common cellular mechanisms for regulating P-selectin surface expression exist among platelets, endothelial cells, and these pancreatic tumor cells. The finding that P-selectin is expressed by metastatic pancreatic tumor cells demonstrates that the range of cell types that express these adhesion molecules is broader than believed previously.

Adenocarcinoma↗
PubMed1997

Effect of regional myocardial perfusion abnormalities on regional myocardial early diastolic function in patients with hypertrophic cardiomyopathy.

Nonuniform hypertrophy of the left ventricle is an important factor in regional diastolic dysfunction in patients with hypertrophic cardiomyopathy (HCM). However, the effect of myocardial perfusion abnormalities on regional diastolic dysfunction has not been established in patients with HCM. We investigated the relationship between regional myocardial perfusion abnormalities and regional early diastolic function in 31 patients with HCM and 8 control patients. Short-axis images of the left ventricle recorded by cine magnetic resonance imaging were divided into ten blocks. The time-to-peak-wall-thickness-thinning rate (TPWR) and the wall thickness were measured in each block. Of the 310 blocks from the patients with HCM, 242 (78%) showed normal thallium-201 uptake (group 1), 40 (13%) showed slightly decreased uptake (group 2), and 28 (9%) showed markedly decreased uptake (group 3). There was no difference in the regional wall thickness among the three groups. The TPWR was longer in patients with HCM than in control patients. It was significantly longer in group 3 (190+/-45ms) than in group 1 (167+/-36 ms) and group 2 (160+/-31 ms). (P < 0.01). The linear regression slope of the relationship between the TPWR and the regional wall thickness was significantly steeper in group 3 than in groups 1 and 2 (P < 0.05). In conclusion, abnormalities in regional myocardial perfusion, in addition to regional hypertrophy, contributed to the regional early diastolic dysfunction in patients with HCM.

Adult↗
PubMed1997

Myocardial clearance of I-123 metaiodobenzylguanidine in dilated cardiomyopathy.

We present the results of sequential imaging studies conducted in two patients with dilated cardiomyopathy whose responses to long-term beta-blocker therapy differed. We evaluated the time course of the myocardial clearance and the heart to upper mediastinal ratios of I-123 metaiodobenzylguanidine (MIBG) scintigraphy. In the first patient, the left ventricular ejection fraction as well as the clinical symptoms were improved by long-term beta-blocker therapy with a concurrent normalization of the myocardial clearance and the heart to upper mediastinal ratio of I-123 MIBG scintigraphy. The myocardial clearance and the upper mediastinal ratio of I-123 MIBG indicated no improvement in the second patient, and the left ventricular function did not change. The myocardial clearance and the heart to upper mediastinal ratio of I-123 MIBG scintigraphy were useful in evaluating the efficacy of long-term beta-blocker therapy in patients with dilated cardiomyopathy.

3-Iodobenzylguanidine↗
PubMed1996

Uniquely abnormal intracavitary flow during late systole and relaxation in hypertrophic obstructive cardiomyopathy with midventricular obstruction.

We describe a patient with hypertrophic cardiomyopathy who had a uniquely abnormal jet from the base to the apex during late systole and the relaxation period. This 48-year-old woman was admitted with exertional dyspnea and palpitations. Two-dimensional echocardiography revealed asymmetric septal hypertrophy and a left midventricular obstruction at the level of the papillary muscles. A high-velocity ejectional jet (peak velocity 4.8 m/s) directed toward the base during systole and an abnormal jet (peak velocity 2.2 m/s) directed toward the apex during late systole and the relaxation period were demonstrated through the midventricular obstruction site using Doppler echocardiography. The peak systolic pressure gradient between the apical and the basal chamber was 91 mmHg, and the peak systole pressure was higher in the apical chamber than in the basal chamber. However, a reverse pressure gradient was revealed between the two chambers during late systole and the relaxation period when the abnormal jet was demonstrated.

Cardiomyopathy, Hypertrophic↗
PubMed1996

Adenocarcinoma in the anal canal associated with a fistula: report of a case.

Adenocarcinoma in the anal canal associated with an anal fistula is extremely rare, and in most cases its origin is difficult to ascertain because the primary sites have already been destroyed before any diagnosis of malignancy is able to be made. We report herein the case of a 62-year-old man found to have papillary adenocarcinoma with partial mucinous carcinoma associated with an anal fistula. The tumor was not exposed to the mucosal surface of the anal canal or rectum and an abdominoperineal resection was carried out. Macroscopic findings suggested that the tumor had developed from the anal fistula; however, the tumor showed a positive results when tested for O-acetylated sialic acids. This test also proved positive in the mucus of normal rectal mucosa, but not in the mucus of the anal glands. We speculated that the results of these tests may indicate that this tumor could have originated from the rectal mucosa, from where it migrated into the anal fistula.

Adenocarcinoma, Mucinous↗
PubMed1996

Regional left ventricular contractile dynamics in hypertrophic cardiomyopathy evaluated by magnetic resonance imaging.

To assess regional myocardial function in hypertrophic cardiomyopathy (HCM), we examined systolic wall thickening (%WT) and percent change of segmental wall area (%AR) by cine magnetic resonance imaging. We studied 23 normal volunteers without evidence of heart disease (group 1) and 40 patients with HCM (group 2). Short-axis images of the left ventricle were recorded at the base and the apex, and were divided into five segments. There were no significant differences in %WT and %AR among the segments in group 1, while %WT and %AR at the apex were higher than values for corresponding segments at the base. The patients with HCM (group 2) were classified into three groups according to end-diastolic wall thickness: group 2a, less than 12 mm; group 2b, 12-15 mm and group 2c, greater than 15 mm. Both the %WT and %AR at the base were significantly higher in group 2a than in the other groups, but were significantly lower in group 2c than in group 1 or group 2a (%WT and %AR in groups 1, 2a, 2b, and 2c respectively: 51 +/- 29 and 19 +/- 17; 83 +/- 40 and 34 +/- 18; 47 +/- 38 and 16 +/- 14; and 32 +/- 21 and 9 +/- 8). Both %WT (40 +/- 24) and %AR (14 +/- 12) at the apex were significantly lower in group 2c than in the other groups (87 +/- 45 and 38 +/- 31 in group 1; 89 +/- 41 and 39 +/- 31 in group 2a; and 61 +/- 27 and 24 +/- 15 in group 2b). Myocardial shortening in the normal volunteers was greater at the apex than at the base. In patients with HCM, regional myocardial function was decreased in association with the degree of hypertrophy, with the wall function of the normal segments appearing to be increased in a possible compensatory mechanism.

Adult↗
PubMed1996

Evaluation of autonomic nervous activity in patients with congenital long QT syndrome by an analysis of RR variability.

Congenital long QT syndrome (LQTS) is a rare hereditary disease characterized by a prolonged QT interval and lethal ventricular tachycardia (Torsades de Pointes: TdP). The pathogenesis of LQTS and the induction of TdP have been thought to be closely related to autonomic nervous abnormalities. We examined autonomic activity in 13 LQTS patients by analyzing heart rate variability from 24 h Holter ambulatory electrocardiographic recordings without medications. In a frequency-analysis of RR variability, we calculated the power in the low-frequency domain (LF) and the high-frequency domain (HF) over 24 h. The ratio of LF to HF (an index of sympathetic nervous activity) was lower in LQTS patients than in controls, whereas HF (an index of parasympathetic nervous activity) was higher. Moreover, LQTS patients with TdP had lower abnormal sympathetic nervous activity than those without TdP. The index of autonomic nervous activity obtained using this method could be useful for evaluating the severity in LQTS.

Adult↗
PubMed1996

Assessment of regional early diastolic function using cine magnetic resonance imaging in patients with hypertrophic cardiomyopathy.

In patients with hypertrophic cardiomyopathy (HCM), we conducted cine magnetic resonance imaging (MRI) studies in which our objectives were to quantify the regional early diastolic function of the left ventricle and to evaluate the relationship between regional diastolic function and hypertrophy. Short-axis images of the left ventricle were recorded by cine MRI in 8 control patients and 24 patients with HCM. The images were then divided into 10 blocks to evaluate regional early diastolic function. The regional wall-thickness-time curve, the radius-time curve, and their first-derivative curves were computed for each of the 10 blocks. There was no difference between the time-to-peak-radius-increasing ratio and the time-to-peak-wall-thickness-thinning ratio in the 10 blocks in the control patients. These 2 parameters in the patients with HCM were significantly longer than those in the control patients. There was also a significant linear correlation between the time-to-peak-wall-thickness-thinning ratio and regional wall thickness. Cine MRI was useful for evaluating regional early diastolic function, which is apparently related to regional hypertrophy, in patients with HCM.

Adult↗