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K Shimomura

Publications and source records attributed to K Shimomura.

At least 19 recordsLinked to original sources
PubMed1992

Frequency analysis of signal-averaged electrocardiogram in patients with right ventricular tachycardia.

OBJECTIVES: The purpose of this study was to analyze the frequency content of signal-averaged electrocardiograms (ECGs) in patients with idiopathic ventricular tachycardia of right ventricular origin and in patients with arrhythmogenic right ventricular dysplasia. BACKGROUND: The late potentials in the time domains are usually found in patients with arrhythmogenic right ventricular dysplasia. They are not usually found in patients with idiopathic ventricular tachycardia of right ventricular origin. METHODS: Fast Fourier transform analysis of signal-averaged ECGs was performed with the use of a Blackman-Harris window in 43 subjects: 20 normal volunteers (group I), 12 patients with idiopathic ventricular tachycardia of right ventricular origin (group II) and 11 patients with arrhythmogenic right ventricular dysplasia (group III), and the frequency spectrum was displayed in a three-dimensional graph. Area ratio (ratio of the area under the spectral plot from 40 to 120 Hz to the area from 0 to 120 Hz) was calculated in all subjects. RESULTS: Area ratio was significantly higher in group II than in group I (243 +/- 45 vs. 196 +/- 15, p < 0.01) and significantly higher in group III (396 +/- 51) than in group I or II (p < 0.001). The high frequency components in group II were confined within the QRS complex in the three-dimensional graph, whereas those in group III extended outside the QRS complex. CONCLUSIONS: Frequency analysis of the signal-averaged ECG with fast Fourier transform analysis can detect the high frequency components in patients with right ventricular tachycardia, including idiopathic ventricular tachycardia and arrhythmogenic right ventricular dysplasia.

Adult↗
PubMed1992

Bradycardia-induced abnormal QT prolongation in patients with complete atrioventricular block with torsades de pointes.

Fourteen patients with complete atrioventricular block with or without torsades de pointes (TdP) were included in this study. They were divided into 2 groups, 6 patients with TdP (TdP[+] group) and 8 patients without TdP (TdP[-] group). The patients were evaluated at 2 different periods, before (acute period) and after (chronic period) pacemaker implantation. In the acute period, the QRS and heart rate during the escape rhythm were not significantly different between the 2 groups; however, the QT and QTc intervals were significantly longer in the TdP(+) group than in the TdP(-) group: 753 +/- 57.5 vs 635 +/- 78.4 ms (p less than 0.01) and 585 +/- 44.8 vs 476 +/- 58.3 ms (p less than 0.01). In the chronic period (greater than 2 months after pacemaker implantation), we changed the pacemaker rate from 90 or 100 beats/min to 50 beats/min and examined the QT interval changes in relation to the heart rate. The QT interval in the TdP(+) group was significantly prolonged compared with the TdP(-) group when the pacing rate was decreased less than or equal to 60 beats/min: 551 +/- 40 vs 503 +/- 36 ms at 60 beats/min (p less than 0.05), and 700 +/- 46 vs 529 +/- 43 ms at 50 beats/min (p less than 0.001). Patients with complete atrioventricular block with TdP had a bradycardia-sensitive repolarization abnormality and this characteristic remained after pacemaker implantation. The critical heart rate that induced abnormal QT prolongation in the TdP(+) group was less than or equal to 60 beats/min.

Adult↗
PubMed1992

Induction of TU abnormalities in patients with torsades de pointes.

1. TU abnormalities could be induced by the specific interventions in the majority of the patients with TDP in chronic stage: isoproterenol in congenital long QT patients, disopyramide in Ia-related TDP patients, and slow heart rate in bradycardia-related TDP patients. 2. Humps in MAP could be recorded in all patients with congenital long QT syndrome by isoproterenol, in half of the patients with Ia-related TDP by disopyramide, but in none of the control patients by these agents. 3. The results suggested that TU abnormalities and the occurrence of hump in MAP were hypersensitive reactions. 4. The results also suggested that specific intervention was not enough for the appearance of marked TU abnormalities in some TDP patients, especially in Ia-related TDP patients. Additional aggravating factors were probably required for marked TU abnormalities and the occurrence of TDP in these patients.

Action Potentials↗
PubMed1992

Application of fuzzy logic to the Apgar scoring system.

Apgar fuzzy expert system (AFES) applied fuzzy logic to the Apgar Scoring System (APG). We prepared the AFESs for both an inexperienced obstetrician (resident A) and an experienced obstetrician (specialist B) separately. We then compared their evaluations of the same 80 neonates at 1 min after birth using both the AFES and the APG. Analysis of the relationship of the general evaluation by the APG (scores below 6 or over 7) and the AFES (bad or good) to the umbilical arterial blood gases (pH below or above 7.20) showed that the sensitivities were 0.36 for the APG evaluation by resident A, 0.50 for the APG evaluation by specialist B, 0.60 for the AFES rating by resident A, and 0.71 for the AFES rating by specialist B. The specificities were 0.94, 0.95, 0.97 and 0.97, respectively. These results demonstrated that the AFES was capable of reflecting the recognition of the examiner.

Apgar Score↗
PubMed1992

Separation and concentration of delta 17-6-keto-PGF1 alpha using monoclonal antibody to omega 3-olefin structure of trienoic prostanoids.

A monoclonal antibody against cis-3-hexen-1-ol was prepared and used to separate and/or concentrate delta 17-6-keto-prostaglandin F1 alpha (PGF1 alpha) in the human sera. cis-3-Hexen-1-ol was conjugated with the human serum albumin (HSA) according to the N-succinimidylester method and hyperimmunized to BALB/c mouse. The monoclonal antibodies were obtained from hybridoma clones established by a fusion between SP2/0-Ag14-k13 mouse myeloma cells and splenocytes of a mouse. A monoclonal antibody, named 4G9-12B, recognized the epitope characteristic for omega 3-olefin structure. The 4G9-12B antibody became more specific for delta 17-6-keto-PGF1 alpha than 6-keto-PGF1 alpha by applying inhibition ELISA using amino-residue coating plates. Using the prepared immunoaffinity columns of this antibody, delta 17-6-keto-PGF1 alpha was clearly detected in 6 pg/ml of the human blood sera by GC/MS analysis. These results suggest that the monoclonal antibody to the partial structure of trienoic prostanoid, omega 3-olefin unit, and that its immunoaffinity columns are useful in separating and concentrating delta 17-6-keto-PGF1 alpha in the human blood or urine.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Effects of a combination of disopyramide and mexiletine on the anterograde accessory pathway conduction in patients with Wolff-Parkinson-White syndrome.

In order to evaluate the electrophysiological effects of the combined administration of disopyramide and mexiletine on anterograde accessory pathway conduction, we studied 11 patients with Wolff-Parkinson-White (WPW) syndrome. Disopyramide was first infused intravenously at 1 mg kg-1 for 5 min followed by a continuous infusion at 0.025 mg kg-1 min-1. After the infusion rate of disopyramide was decreased to 0.004 mg kg-1 min-1 to maintain a lower serum concentration, mexiletine was infused at 2 mg kg-1 for 5 min followed by a continuous infusion at 0.008 mg kg-1 min-1 (protocol 1). The shortest atrial paced cycle length with 1:1 anterograde accessory pathway conduction (shortest CL with 1:1) and the anterograde effective refractory period of the accessory pathway (ERP) were measured: (1) before drug administration, (2) after disopyramide was given alone, and (3) after disopyramide and mexiletine were combined at lower concentrations. The same protocol was repeated with the order of drug administration reversed (mexiletine followed by disopyramide) in all patients (protocol 2). Both disopyramide and mexiletine lengthened the shortest CL with 1:1 and the ERP to the same degree. The combination of disopyramide and mexiletine at lower concentrations further lengthened the shortest CL with 1:1. It was longer than with disopyramide (protocol 1) or mexiletine (protocol 2) alone [protocol 1: 412 +/- 169 ms (combination) vs 356 +/- 117 ms (disopyramide); P less than 0.05, protocol 2: 409 +/- 166 ms (combination) vs 355 +/- 119 ms (mexiletine); P less than 0.01].(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Significance of ventricular pacing site in manifest entrainment during orthodromic atrioventricular reentrant tachycardia with left-sided accessory pathway.

We examined entrainment by ventricular pacing in six patients during orthodromic atrioventricular reentrant tachycardia (AVRT) utilizing a left-sided lateral accessory pathway. Constant fusion and progressive fusion were demonstrated in all patients by left ventricular pacing during tachycardia, but in none of the patients by right ventricular pacing. When left ventricular pacing was performed during AVRT, the antidromic wave front from the pacing impulse (n) collided with the orthodromic wave front of the previous pacing beat (n - 1) within the ventricle, therefore, constant fusion and progressive fusion were demonstrated in the surface electrocardiographic QRS complexes. On the other hand, when right ventricular pacing was performed during orthodromic AVRT, the antidromic wave front from the pacing impulse (n) collided with the orthodromic wave front of the previous paced beat (n - 1) within the normal atrioventricular pathway, and constant fusion and progressive fusion were therefore not demonstrated. These phenomena were explained by the relationship of the ventricular pacing site and the reentrant circuit. This study demonstrates the importance of the pacing site in manifest entrainment of orthodromic AVRT during ventricular pacing.

Adult↗
PubMed1992

Spectral analysis of signal-averaged electrocardiograms in patients with idiopathic ventricular tachycardia of left ventricular origin.

BACKGROUND: The signal-averaged ECG has been used to detect late potentials, and it is considered a noninvasive marker for areas of slow conduction requisite for reentrant arrhythmia. Late potentials are not usually found in patients with idiopathic ventricular tachycardia (VT); nevertheless, fragmented electrograms are often recorded in those patients during endocardial mapping. The purpose of this study was to investigate the spectral content of the signal-averaged ECGs with use of fast Fourier transform analysis (FFT) in patients with idiopathic VT of left ventricular origin. METHODS AND RESULTS: Signal-averaged ECGs were recorded in 12 patients with idiopathic VT originating from the left ventricle (group 1) and 25 age-matched normal volunteers (group 2). Frequency analysis with FFT was performed with a Blackman-Harris window in a segment length of 120 msec from 40 msec before the end of the QRS complex, and the frequency spectrum was displayed in a three-dimensional graph. Area ratio 1 (area of 20-50 Hz/area of 10-50 Hz) and area ratio 2 (area of 40-100 Hz/area of 0-40 Hz) were calculated in all subjects. Late potentials defined by the time domain were negative in all subjects. The area ratios of group 1 were significantly higher than those of group 2. High-frequency components in the three-dimensional graph were confined within the QRS complex. CONCLUSIONS: These results suggest that frequency analysis of signal-averaged ECGs with FFT is an available method for detecting the high-frequency component within the QRS complex in some patients with idiopathic VT of left ventricular origin.

Adult↗
PubMed1992

[Long-term follow-up of exercise tolerance after coronary bypass grafting].

Six hundred forty-eight serial graded exercise tests were performed on 400 patients up to 10 years after coronary bypass graftings (CABG). The maximal attained exercise tolerance, over 10 METS, were observed in 60% of patients and the negative response to exercise test in 43% of patients. The positive response in various parameters were observed at the following rates: graft occlusion-30% vs graft patent-46% (p less than 0.01); incomplete revascularization-39% vs complete revascularization-22% (p less than 0.01); and less than or equal to 8 METS 4-45% vs greater than or equal to 10 METS-28% (p less than 0.01), respectively. However, no significant difference was observed among number of vessels diseased, number of graftings, and presence of old myocardial infarction. The maximal attained stage of exercise, over 10 METS, in various parameters were at the following rates: less than or equal to 59 years old-70% vs greater than or equal to 60 years old-44% (p less than 0.01); male-63% vs female-32% (p less than 0.01); and graft patent-63% vs graft occlusion-50% (p less than 0.05), respectively. The serial analysis of exercise test demonstrated that improved exercise tolerance appears to persist for at least 5 years after CABG. However, the patients in complete revascularization had a tendency to increase the rate of positive response. In conclusion, the completeness of revascularization as well as graft patency was the main factor limiting exercise tolerance, and correlates with the extent and the duration of improvement after CABG.

Coronary Artery Bypass↗
PubMed1991

A monoclonal antibody to scopolamine and its use for competitive enzyme-linked immunosorbent assay.

A hybridoma clone producing a monoclonal antibody (SC78.H81) against scopolamine was established. The monoclonal antibody was an IgG1 (k) antibody with high affinity (1.6 x 10(9) M-1 for methylscopolamine). The monoclonal antibody was cross-reactive with methylscopolamine and butylscopolamine, and showed weak cross-reactivity with 6 beta- and 7 beta-hydroxyhyoscyamine. The cross-reaction with L-hyoscyamine, atropine, scopine and DL-tropic acid was very weak. A competitive enzyme-linked immunosorbent assay using SC78.H81 was established to quantify scopolamine. The sensitivity of the assay allowed detection of 20 pg assay-1 (0.2 ng ml-1) of scopolamine. The assay was applied to the estimation of scopolamine content in hairy root cultures of a Duboisia hybrid.

Antibodies, Monoclonal↗
PubMed1991

Chaos and fractals which 1/f spectrum below 10(-2) Hz demonstrates full-term fetal heart rate changes during active phase.

Human fetal heart rate changes were analysed using power spectral density (PSD). The data for analysis were obtained from 25 normal fetuses between the 37th and 40th week of gestation. Pulse interval distribution showed an almost Gaussian distribution. PSD was calculated by first Fourier transform technique, and showed the particular fluctuation below 10(-2) Hz to be inversely proportional to frequency (so called '1/f spectrum') during the active phase after the 37th week of gestation. These results revealed that the 1/f spectrum of the human heart rate had already appeared below 10(-2) Hz in full term of pregnancy.

Echocardiography↗
PubMed1991

Differential response of QTU interval to exercise, isoproterenol, and atrial pacing in patients with congenital long QT syndrome.

Sympathetic stimulation is well known to contribute to the genesis of QTU prolongation and ventricular tachyarrhythmias in patients with congenital long QT syndrome. In this study, we performed exercise treadmill testing, isoproterenol infusion (1-2 micrograms/min), and right atrial pacing (cycle length 500 msec) in 11 patients with congenital long QT (LQT) syndrome (LQT group) and in 12 age- and sex-matched controls (control group). The responses of the corrected QT (QTc; Bazett's method) interval and the TU wave complex were evaluated. The QTc interval was prolonged from 482 +/- 63 msec1/2 to 548 +/- 28 msec1/2 by exercise in the LQT group (n = 11; P less than 0.005), and this was associated with fusion of the T waves with enlarged U waves, whereas the QTc interval did not increase with exercise in the control group (n = 12; 402 +/- 19 msec1/2 vs 409 +/- 22 msec1/2). The QTc interval was also prolonged from 466 +/- 50 msec1/2 to 556 +/- 33 msec1/2 by isoproterenol in the LQT group (n = 7; P less than 0.005) in association with morphological changes of the TU wave complex like those seen with exercise, whereas it was only slightly increased from 399 +/- 10 msec1/2 to 436 +/- 13 msec1/2 by isoproterenol in the control group (n = 77; P less than 0.001). However, the QTc interval did not increase with atrial pacing in the LQT group (n = 8; 476 +/- 57 msec1/2 vs 486 +/- 59 msec1/2), whereas it was slightly increased from 400 +/- 21 msec1/2 to 426 +/- 18 msec1/2 by atrial pacing in the control group (n = 8; P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Repetitive nonsustained monomorphic ventricular tachycardia aborted by methoxamine and sleep "heart rate dependent ventricular tachycardia".

Methoxamine, an alpha adrenoreceptor agonist, and sleep abolished repetitive nonsustained monomorphic ventricular tachycardia in a 41-year-old man without detectable underlying heart disease. Detailed pacing studies revealed that the occurrence of ventricular tachycardia was totally dependent on the basic heart rate. Sleep and the alpha adrenoreceptor agonist abolished the ventricular tachycardia by slowing the basic heart rate. Verapamil, propranolol, and disopyramide were able to decrease the upper limit of the tachycardia-initiating heart rate, but none of them were able to increase the lower limit (75/min). Failure to increase the lower limit of the tachycardia-initiating heart rate was a major reason why these conventional antiarrhythmic drugs were unable to suppress his daytime episodes of repetitive ventricular tachycardia.

Adult↗
PubMed1991

Dominance of blood pressure in natriuresis associated with supraventricular tachycardia.

Supraventricular tachycardia was induced in 10 patients by programmed cardiac stimulation through esophageal lead. Blood pressure, heart rate, renal function, and hormonal factors were measured before, during, and after tachycardia. The patients were divided into two groups, depending on whether antinatriuresis occurred during tachycardia; one group (n = 5) with antinatriuresis during tachycardia associated with a decrease in blood pressure and the other group (n = 5) with neither antinatriuresis nor changes in blood pressure. The urinary sodium excretion tended to increase after tachycardia only in the latter group. On the other hand, urine volume and free water clearance increased during or after tachycardia in both groups. Plasma levels of atrial natriuretic peptide significantly increased and the urinary vasopressin excretion significantly decreased during tachycardia in both groups. During tachycardia, natriuresis due to atrial natriuretic peptide secretion seems to be hampered by hypotension, but polyuria is preserved despite the fall in blood pressure probably related to suppression of vasopressin release.

Adult↗
PubMed1991

Changes in auditory brainstem responses of normal neonates immediately after birth.

To clarify the functional changes in the acoustic conduction pathway in the human immediately after birth, auditory brainstem responses (ABR) in 58 normal neonates were examined. In longitudinal and cross-sectional analysis, the peak latency of wave 1 showed significant shortening (p less than 0.05) from 1.82 +/- 0.23 ms (mean +/- SD) at 30 min after birth to 1.69 +/- 0.26 ms at 2 h after birth. It continued to decrease gradually therafter. The interpeak latency of waves 1-3 decreased gradually (not significant) from 2.82 +/- 0.19 ms (30 min after birth) to 2.74 +/- 0.15 ms (1 month after birth), while the interpeak latency of waves 3-5 decreased significantly from 2.63 +/- 0.27 ms (30 min after birth) to 2.47 +/- 0.23 ms (24 h after birth; p less than 0.01). These results indicate that functional changes in the acoustic system immediately after birth represent rapid adaptation of the peripheral region to extrauterine environment and development of the more central region.

Evoked Potentials, Auditory, Brain Stem↗
PubMed1991

Early afterdepolarizations induced by isoproterenol in patients with congenital long QT syndrome.

BACKGROUND: Several recent experimental and clinical studies have shown that early afterdepolarizations (EADs) are important in the genesis of QTU prolongation and ventricular tachyarrhythmias (VTs) in patients with long QT syndrome. On the other hand, sympathetic stimulation is well known to contribute to the genesis of QTU prolongation and VTs in patients with congenital long QT syndrome. The present study was performed to examine the influence of isoproterenol on the genesis of EADs and on the action potential durations and QTU intervals in patients with congenital long QT syndrome. METHODS AND RESULTS: We recorded monophasic action potentials (MAPs) with a contact electrode during right atrial pacing at a constant cycle length of 500 msec before and after continuous isoproterenol infusion (1 microgram/min). MAPs were obtained from the right and left ventricular endocardium in six patients with congenital long QT syndrome (LQT group, 18 recording sites) and in eight control patients (control group, 19 recording sites). Although no EADs were recorded from either group during the control state, MAP duration at 90% repolarization (MAPD90) was significantly longer in the LQT group (n = 18) than in the control group (n = 19) (275 +/- 36 versus 231 +/- 22 msec; p less than 0.0005). Isoproterenol induced EADs in four of the six LQT patients (five of 18 recording sites) but not in the eight control patients (zero of 19 recording sites). The appearance of EADs in the LQT group was associated with an increased amplitude of the late component of the TU complex, and the corrected QT (QTc) interval was prolonged by isoproterenol from 543 +/- 53 to 600 +/- 30 msec 1/2 (n = 6; p less than 0.05). Isoproterenol also prolonged the MAPD90 from 275 +/- 36 to 304 +/- 50 msec in the LQT group (n = 18; p less than 0.005), whereas it shortened the MAPD90 from 231 +/- 22 to 224 +/- 25 msec in the control group (n = 19; p less than 0.05). Moreover, isoproterenol increased the dispersion of MAPD90 (difference between the longest MAPD90 and the shortest MAPD90 in each patient) from 30 +/- 5 to 62 +/- 35 msec in the LQT group (n = 6; p = 0.08), whereas it did not change the dispersion of MAPD90 in the control group (n = 8; 25 +/- 14 versus 27 +/- 14 msec). CONCLUSIONS: These results suggest that patients with congenital long QT syndrome have primary repolarization abnormalities and that EADs induced by isoproterenol play an important role in the exaggeration of these repolarization abnormalities.

Action Potentials↗
PubMed1991

Antitumor effects of droloxifene, a new antiestrogen drug, against 7,12-dimethylbenz(a)anthracene-induced mammary tumors in rats.

The antitumor effects of droloxifene (DROL, (E)-alpha-[p-[2-(dimethylamino)ethoxy]-phenyl]-alpha-ethyl-3-stilbeno l), a new antiestrogen drug, on 7,12-dimethylbenz(a)anthracene (DMBA)-induced estrogen-dependent mammary tumors in rats were studied and compared with those of tamoxifen (TAM). Mammary tumors appeared from about 2 months after p.o. administration of DMBA to female rats, and all of them were estrogen receptor (ER) and progesterone receptor positive. DROL and TAM (p.o.) inhibited the growth of the tumors. Both drugs inhibited the binding of 125I-estradiol-17 beta to ER in the cytosol of the tumor in vitro, and the effect of DROL was much stronger than that of TAM. When 3H-estradiol-17 beta (3H-E2) was given s.c. to rats with the mammary tumors, 3H-E2 accumulated in the tumors, uteri and vaginae in which the ER levels are known to be high, but was low in the heart, in which the ER levels are normally low. DROL and TAM decreased the levels of 3H-E2 in the tumors, uteri and vaginae, but had no effect in the hearts. When DROL or TAM was given p.o. to rats daily for 7 consecutive days after administration of DMBA, they inhibited the induction of mammary tumors by DMBA. From these results, DROL inhibits the growth and the initiation of DMBA-induced mammary tumors by inhibiting the binding of estrogen to its receptor.

9,10-Dimethyl-1,2-benzanthracene↗