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Biomedical subjects

T Ohe

Publications and source records attributed to T Ohe.

At least 127 records · Page 7Linked to original sources
PubMed1995

Salutary effect of disopyramide on left ventricular diastolic function in hypertrophic obstructive cardiomyopathy.

OBJECTIVES: The purpose of this study was to estimate the effect of disopyramide on left ventricular diastolic function in patients with hypertrophic obstructive cardiomyopathy. BACKGROUND: Although disopyramide has been reported to lessen clinical symptoms in patients with hypertrophic obstructive cardiomyopathy, few data exist regarding its effect on diastolic function in these patients. METHODS: Thirteen patients with hypertrophic cardiomyopathy (six with and seven without left ventricular outflow obstruction) were examined. Before and after intravenous disopyramide, hemodynamic and angiographic studies were performed. RESULTS: In patients with outflow obstruction, pressure gradient at the outflow tract decreased from a mean +/- SD of 100 +/- 45 to 26 +/- 33 mm Hg (p < 0.01). Although systolic function was similarly impaired in both groups, the time constant of left ventricular pressure decay (tau) shortened from 56 +/- 10 to 44 +/- 8 ms (p < 0.01) and the constant of left ventricular chamber stiffness (kc) decreased from 0.049 +/- 0.017 to 0.038 +/- 0.014 m2/ml (p < 0.01) only in patients with outflow obstruction. Shortening in tau correlated best with decrease in left ventricular systolic pressure (r = 0.84, p < 0.01). In contrast, tau was prolonged from 52 +/- 10 to 64 +/- 11 ms (p < 0.01) and kc was unchanged in patients without outflow obstruction. CONCLUSIONS: The primary effects of disopyramide on the hypertrophied left ventricle were negative inotropic and negative lusitropic. However, left ventricular diastolic properties in patients with outflow obstruction were improved with a decrease in outflow pressure gradient. Relief of clinical symptoms in hypertrophic obstructive cardiomyopathy with disopyramide might be due in part to improvement of diastolic function, which appears secondary to the reduction in ventricular afterload.

Adult↗
PubMed1995

Physiological and pathological responses of TU waves to class Ia antiarrhythmic drugs.

Abnormal repolarization associated with torsades de pointes is expressed as QT prolongation. The physiological response to class Ia antiarrhythmic drugs is also reflected in prolongation of the QT interval. However, the essential difference between pathological and physiological prolongation is not clear. The purpose of this investigation was to differentiate between pathological and physiological changes in the repolarization waves of surface electrocardiograms (ECG) induced by class Ia drugs. In 18 patients without a history of torsades de pointes or syncope (control group), TU waves were compared before and after the administration of class Ia drugs (physiological response). In eight patients with torsades de pointes induced by class Ia drugs (torsades de pointes group), the TU waves at torsades de pointes were compared with those before drug administration (pathological response). In the control group, although the QTc (measured in lead II and corrected for heart rate by Bazett's formula) was increased significantly (0.40 +/- 0.04 to 0.44 +/- 0.05 s, P < 0.001), the U-amp (amplitude of the U wave measured in a precordial lead where the T and U waves were clearly differentiated) remained unchanged. In the torsades de pointes group, however, the QTc was increased (0.42 +/- 0.04 to 0.54 +/- 0.07 s, P < 0.02); the U-amp was also increased, significantly (0.09 +/- 0.07 to 0.27 +/- 0.18 mV, P < 0.05). Thus, enlargement of the U wave may help to differentiate between the physiological and pathological responses to class Ia drugs.

Anti-Arrhythmia Agents↗
PubMed1995

Dynamic relationship between the Q-aT interval and heart rate in patients with long QT syndrome during 24-hour Holter ECG monitoring.

The purpose of this study was to investigate the dynamic relationship between heart rate and the Q-aT interval (the interval from the Q wave to the T wave apex) in patients with long QT syndrome. The QT to heart rate relation is useful for evaluating abnormalities of the ventricular repolarization, but its clinical application to the long QT syndrome requires accurate computer aided measurement of the QT interval and the sampling of a large number of beats. Therefore, the Q-aT interval was used on the basis of some reports that the heart rate dependency of the QT interval was concentrated in the Q-aT interval. Recent advances in the computer technology have allowed analysis of the relationship between the Q-aT and RR intervals on Holter ECG recordings. However, in addition to a prolonged QT interval, most patients with long QT syndrome have bizarre and variable T waves and the influence of this T wave morphology on the Q-aT to heart rate relation has not been clarified. We investigated the dynamic relationship between the Q-aT interval and heart rate in 10 patients with long QT syndrome and 11 control subjects using our original computer algorithm for the analysis of 24-hour Holter ECG recordings. The patients showed morphological T wave changes associated with heart rate changes during Holter recordings and these affected the Q-aT interval. The patients showed the following characteristics in the relationship between the major T wave peak and the RR interval: (1) a modestly decreased correlation between Q-aT and RR than in the control subjects (a median r value of 0.87 vs 0.93; P = 0.001); and (2) a steeper Q-aT/RR slope than in controls (a median slope of 0.24 vs 0.16; P < 0.05). Abnormal and variable T wave morphology in the long QT patients was closely related to a modestly decreased correlation between Q-aT and RR than in the control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Abnormal response to exercise, face immersion, and isoproterenol in children with the long QT syndrome.

The present study was performed to observe the change of QT interval by sympathetic stimulations in patients with the long Qt syndrome (LQTS). The study group consisted of 6 children with LQTS and 6 healthy children without QT prolongation. All LQTS patients had syncopal episodes. The QTc and delta QTc% ([QTc interval after examination-QTc interval at rest]/ QTc interval at rest x 100) by treadmill testing, face immersion, and isoproterenol were examined. One minute after peak exercise of treadmill testing, the changes in the QTc interval were not significant in either group, but delta QTc% was larger in the LQTS group than in the control group (+ 11.0 +/- 12.1% vs -2.6 +/- 3.2%; P = 0.02). The QTc interval at the shortest RR interval during face immersion was prolonged in the LQTS group (0.47 +/- 0.01 s to 0.51 +/- 0.04 s; P = 0.02), but there were no significant changes in the control group (0.40 +/- 0.03 s to 0.41 +/- 0.03 s; P = NS). delta QTc% was larger in the LQTS group than in the control group (+ 10.0 +/- 7.3% vs +1.1 +/- 5.5%; P = 0.04). In the LQTS group, the RR interval was shortened (P = 0.009) and QTc interval was prolonged (P = 0.0008) after isoproterenol infusion. These sympathetic stimulations amplified the TU abnormality in the LQTS group. By observing the TU changes caused by face immersion, we hoped to find a possible new method with which to diagnose LQTS. The combination of these examinations may be helpful in screening the borderline cases of TU abnormalities.

Adolescent↗
PubMed1995

Early afterdepolarization abolished by potassium channel opener in a patient with idiopathic long QT syndrome.

We describe a 17-year-old boy with idiopathic long QT syndrome and repeated syncopal episodes. Early afterdepolarization (EAD) in the monophasic action potential (MAP) was demonstrated in the posterior septum of the left ventricle. Injection of the potassium channel opener nicorandil decreased EAD and shortened MAP duration. The syncopal episodes due to ventricular fibrillation disappeared after administration of the potassium channel opener.

Action Potentials↗
PubMed1995

Provocative testing and drug response in a patient with the long QT syndrome.

A girl of 14 with the long QT syndrome (LQTS) and torsades de pointes is reported. Isoprenaline or adrenaline infusions induced torsades de pointes and inversion of the TU wave. Changes in the TU wave during isoprenaline infusion were used to select effective drugs to treat this patient. A beta blocker and calcium channel blocker were selected and the patient had no episodes of syncope for two years. This electrocardiographically guided method may be useful for selecting effective drugs in patients with the LQTS.

Adolescent↗
PubMed1995

Clinical and electrophysiological characteristics of sustained ventricular tachycardia occurring 3 to 21 days after acute myocardial infarction.

Patients with sustained ventricular tachycardia (VT) in the post-infarction period, especially more than 48 h after acute myocardial infarction (AMI), have a high mortality. However, clinical characteristics of these patients are unknown, since previous studies have not clarified the relationship between sustained VT and acute myocardial damage. To clarify the prognostic factors in patients with sustained VT in the early post-infarction period, we retrospectively surveyed 961 consecutive patients with AMI. Eleven patients (9 men and 2 women, aged 54 to 80 years) who had no previous myocardial infarction had at least one documented episode of sustained VT between 3 and 21 days after AMI. Late potentials were detected in 7 of 7 patients who underwent signal-averaged electrocardiography within 2 days after the first occurrence of VT. Entrainment was seen in 2 patients. The 5 patients who died in hospital had the following clinical characteristics: 1) cardiogenic shock, 2) extensive infarction, 3) a short interval from AMI to the onset of VT (mean +/- SD: 4 +/- 2 days), and 4) recurrent and refractory VT. In contrast, the 6 patients who survived had the following clinical characteristics: 1) no cardiogenic shock, 2) a relatively late occurrence of VT (mean = SD: 14 +/- 7 days), 3) few episodes of VT, and 4) no recurrence of VT during the follow-up period of 12 to 58 months. The occurrence of sustained VT within 3 weeks after AMI was influenced by the general condition of the patient, and the prognosis was mainly related to cardiac function.

Aged↗
PubMed1995

Glomerular hemodynamics during supraventricular tachycardia.

Supraventricular tachycardia (SVT) was induced in 7 patients by programmed cardiac stimulation via an esophageal lead. Blood pressure, renal function, and hormonal factors were measured before, during, and after SVT. The glomerular filtration rate increased during SVT, while renal blood flow did not change. The parameters of glomerular hemodynamics were calculated according to the method of Gomez. Glomerular pressure was 64 +/- 3 (mean +/- SE) mmHg before SVT, and rose significantly (p < 0.01) to 76 +/- 5 during SVT. This rise in glomerular pressure was associated with a decrease in afferent vascular resistance (from 3355 +/- 610 to 1770 +/- 517 dynes x sec/cm5, p < 0.05) and an increase in efferent vascular resistance (from 3726 +/- 758 to 4814 +/- 780 dynes x sec/cm5, p < 0.05). Since atrial natriuretic peptide (ANP) increased during SVT (from 40 +/- 15 to 208 +/- 72 pg/ml, p < 0.01), these changes in glomerular hemodynamics may be attributed to the physiologic action of ANP. Despite the changes in glomerular hemodynamics during SVT, natriuresis appeared after SVT and not during SVT. This suggests that natriuresis accompanying SVT could not be attributed to the changes in glomerular hemodynamics.

Adult↗
PubMed1995

[Follow-up study of hepatic hemangiomas].

Hepatic hemangioma is the most common benign tumor of the liver, but there are a few reports on chronological changes in size of hepatic hemangioma. To elucidate natural history of hepatic hemangioma, we evaluated consecutive ultrasonograms of 27 hemangiomas in 23 patients. Underlying liver disease in these 23 patients included seven cases with chronic hepatitis, five cases with liver cirrhosis and three cases with fatty liver. The remaining eight cases showed no evidence of liver disease. Follow-up period ranged 12 to 114 months (average 44). During the follow-up, six (22.2%) hemangiomas changed in size on US, which included three lesions with increase in size, one lesion with decrease in size and two lesions with spontaneous regression. Of 12 patients with chronic liver disease, only one patient showed significant change in the hemangioma size, which regressed spontaneously. These results showed that there was no case showing increase in size of hemangioma in patients with chronic liver disease. Thus, if clinically diagnosed hemangioma which tends to increase in size is detected on US or other imaging modalities in patients with chronic liver disease, aimed aspiration biopsy should be preferably performed considering the possibility of hepatocellular carcinoma.

Adult↗
PubMed1994

Diagnostic value of recovery time measured by body surface mapping in patients with congenital long QT syndrome.

The QT interval of the resting 12-lead electrocardiogram is normal or borderline in some patients with congenital long QT syndrome (LQTS). Recently, several in vivo experimental studies have shown that the time of maximum dV/dt in the ST-T segment is correlated with the time of local ventricular recovery. The purpose of this study was to examine the value of the body surface recovery time measured by 87-lead body surface mapping for detecting LQTS. Body surface mapping and 12-lead electrocardiography were performed simultaneously in 18 patients with LQTS and 40 controls of similar age and sex. The recovery time (RT), that is, the interval between QRS onset and the time of maximum dV/dt in the ST-T segment, was measured automatically by computer from each of the 87 mapping leads, and the corrected RT (RTc) was calculated by Bazett's method. The QT interval was measured from each of the 12 standard electrocardiographic leads, and the corrected QT (QTc) interval was also calculated. The maximum RT and RTc, the minimum RT and RTc, and the RT and RTc dispersions (difference between maximum and minimum RT and RTc in each patient) were significantly longer in the LQTS group than in the control group. In addition, a maximum RT of 390 msec, a maximum RTc of 430 msec 1/2, an RT dispersion of 170 msec, and an RTc dispersion of 170 msec1/2 separated the 2 groups completely (i.e., no overlap). The maximum QT and QTc, the minimum QT and QTc, and the QT and QTc dispersions (difference between maximum and minimum QT and QTc in each patient) were also significantly longer in the LQTS group than in the control group. However, the maximum QTc was normal (< or = 440 msec1/2) or borderline (< or = 460 msec1/2) in 5 of the 18 LQTS patients, and none of these parameters clearly separated the 2 groups. These results suggest that measurement of RT by 87-lead body surface mapping is useful for diagnosing latent or borderline LQTS.

Adolescent↗
PubMed1994

Novel metabolic pathway of arylethers by cytochrome P450: cleavage of the oxygen-aromatic ring bond accompanying ipso-substitution by the oxygen atom of the active species in cytochrome P450 models and cytochrome P450.

We have found a novel metabolic pathway of arylethers, involving the cleavage of the oxygen-aromatic ring bond. When p-(p-nitrophenoxy)phenol was utilized as a substrate, cleaved products, p-nitrophenol and p-benzoquinone, were formed in two cytochrome P450 model systems, meso-tetraphenylporphinatoiron(III) chloride-NaBH4/O2 system and meso-tetrakis (2,6-difluorophenyl)porphinatoiron(III) chloride-m-chloroperoxybenzoic acid (mCPBA) system. Rat liver microsomes also catalyzed this reaction, which was inhibited by a cytochrome P450-specific inhibitor, and it was confirmed that this cleavage proceeded in vivo. Further, experiments using [18O]mCPBA and 18O2 proved that the cleavage reaction is accompanied with the ipso-substitution by the oxygen atom of the active species in both cytochrome P450 model system and cytochrome P450. When the microsomal reactions of p-(p-nitrophenoxy)phenol analogues which lack a hydroxy group, namely p-nitrophenoxybenzene, p-(p-nitrophenoxy)anisole, and p-(p-nitrophenoxy)toluene, were investigated, the cleavage reaction occurred via p-(p-nitrophenoxy)phenol in the cases of p-nitrophenoxybenzene and p-(p-nitrophenoxy)anisole, indicating that a hydroxy group at the p-position to the ether bond is necessary for this pathway. This metabolic pathway appears to be important, because a diarylether linkage, which is very stable and has generally been thought to resist metabolism, is cleaved and benzoquinone, a highly toxic metabolite, is formed.

Animals↗
PubMed1994

Time-domain and frequency-domain analyses of the signal-averaged ECG in patients with sustained ventricular tachyarrhythmia and nonischemic heart diseases.

Signal-averaged electrocardiogram (ECG) variables were analyzed in 81 patients with ventricular tachyarrhythmia and nonischemic heart disease using the ART LVP 101 EPX system (Austin, TX): 15 ventricular tachycardia patients with arrhythmogenic right ventricular dysplasia (ARVD), 7 ventricular tachycardia patients with dilated cardiomyopathy, 25 patients with "idiopathic" verapamil-sensitive left ventricular tachycardia, 24 patients with "idiopathic" right ventricular tachycardia, and 10 "idiopathic" ventricular fibrillation (IVF) patients with rbbb pattern and ST-segment elevation in the precordial leads. Data from 52 normal control subjects were also analyzed. The first study was to test the hypothesis of any difference in signal-averaged ECG indices between patients with ARVD and patients with dilated cardiomyopathy. Longer filtered QRS duration and T40 and higher amplitude of the terminal filtered QRS complex outside the end of the standard QRS complex (log V-outside) were noted in patients with ARVD (filtered QRS duration, 172 vs 144 ms, P < .05; T40, 94 vs 62 ms, P < .05; log V-outside, 1.48 vs 0.56, P < .01). Endocardial mapping showed noticeable extension of fractionated electrograms in the right ventricle and longer duration of fractionated intracardiac electrograms in patients with ARVD, which might explain the difference in signal-averaged ECG indices between these two diseases. The second study was to test the hypothesis of and the variables that can suggest the arrhythmogenic substrate in patients with idiopathic ventricular tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Epinephrine-induced ventricular premature complexes due to early afterdepolarizations and effects of verapamil and propranolol in a patient with congenital long QT syndrome.

We report a patient with congenital long QT syndrome in whom early afterdepolarizations (EADs) were demonstrated on monophasic action potential (MAP) recordings in the left ventricular mid-base inferior wall. Epinephrine infusion at 5 micrograms/min increased the amplitude of the EADs and the late component of the T(U) wave. Epinephrine also induced ventricular premature complexes (VPCs) with right bundle branch block morphology and left-axis deviation that occurred from the peak of the EADs. Verapamil injection (5 mg) during continuous epinephrine infusion abolished all VPCs with a slight reduction in the amplitude of the EADs. Propranolol injection (5 mg) in addition to verapamil further reduced the amplitude of the EADs and the late component of the T(U) wave. These findings suggest that the epinephrine-induced VPCs were closely related to triggered rhythm arising from the EADs, and that both verapamil and propranolol were effective for the suppression of VPCs and EADs.

Action Potentials↗
PubMed1994

[A juvenile case of radiation-induced meningioma two years after radiation for craniopharyngioma].

The patient was a 7-year-old boy who received radiation therapy of 50 Gy after total gross removal of a craniopharyngioma. After two years a follow up CT scan showed a new enhanced lesion in the right temporal tip within the previous irradiation field. Total removal of the tumor was performed and its histological examination showed it to be an atypical meningioma. This atypical meningioma satisfied Cahan's criteria. So we diagnosed this atypical meningioma as radiation-induced meningioma. Immunohistochemically this meningioma stained for Vimentin. An electron-microscopical examination showed neither desmosome nor interdigitation. The score of Ki-67 and BrdU-L. I. was very small. Compared with previously reported juvenile radiation-induced meningioma, the latency was very short. The patient received growth hormone (GH) replacement therapy. We suspected relation between GH replacement therapy and short latency. He was discharged without any new neurological deficits and we haven't detected tumor recurrence for two years.

Child↗