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Biomedical subjects

D Inoue

Publications and source records attributed to D Inoue.

At least 55 records · Page 3Linked to original sources
PubMed1990

[Utility of reinjection method in stress Tl-201 myocardial scintigraphy to assess viability of the infarcted myocardium].

To assess viability of the infarcted myocardium, we performed stress Tl-201 myocardial scintigraphy using reinjection method in 37 patients with old myocardial infarction, and in 13 patients of them, Tl myocardial imagings were performed in resting state on the other day within 4 weeks after this examination. In this method, 111 MBq (3 mCi) of thallium was injected at the peak of exercise and initial and delayed images were acquired, then additionally 37 MBq (1 mCi) of thallium was injected after delayed scanning (reinjection) and we obtained post-reinjection images. Delayed images showed redistribution in 15 patients (41%), and no redistribution in 22 patients (59%). In post-reinjection images, 7 (19%) of 15 patients with redistribution and 3 (8%) of 22 patients without redistribution showed improvement of thallium uptake, in total 10 patients (27%) had additional thallium uptake in infarcted regions. And the degree of thallium uptake in post-reinjection images were almost equal to that in resting images. In conclusion, myocardial imaging using thallium reinjection method may be useful for the assessment of viability of the infarcted myocardium.

Female↗
PubMed1989

Effect of paced cycle length on sinus node effective refractory period before and after autonomic blockade in patients with sick sinus syndrome.

Effect of basic paced cycle length on sinus node effective refractory period was studied in 22 patients with sick sinus syndrome. Sinus node effective refractory period was measured using three different paced cycle lengths before and after pharmacologic autonomic blockade. Sinus node effective refractory period could be measured at one cycle length, at least, in 59% of the patients before blockade, however, it could be measured at two or more cycle lengths in only 18% of patients because of the chaotic response of sinus node against premature stimuli. It could be measured after pharmacologic autonomic blockade in 68% of the patients at two or more paced cycle lengths. On the other hand, the rest of the patients showed no measurable sinus node effective refractory period at any cycle length, for their sinus node effective refractory periods were shorter than their right atrial effective refractory periods. The comparison of sinus node effective refractory period at different paced cycle lengths was unsuccessful before pharmacologic autonomic blockade, while the refractory period was significantly prolonged as cycle length was shortened after blockade. We concluded that (1) sinus node effective refractory period in humans is prolonged as paced cycle length decreases, (2) the autonomic reflex is the major disturbing factor in measuring sinus node effective refractory period, and pharmacologic autonomic blockade can be usefully employed to eliminate a chaotic sinus nodal response, (3) when sinus node effective refractory period is shorter than right atrial effective refractory period, a shorter paced cycle length should be used for definite measurement of the former.

Adolescent↗
PubMed1989

Combined effects of hypoxia and elimination of glucose on resting and postextrasystolic potentiated contractions of papillary muscle of guinea pigs.

We studied the combined effects of hypoxia and the absence of glucose on postextrasystolic potentiated and resting contractions in papillary muscle of guinea pigs. Postextrasystolic potentiations (PESPs) were evoked following trains of 40 externally applied continuous stimulations. During hypoxia resting (regular) contractions decreased to about 25% of baseline tension at 30 degrees C, whereas postextrasystolic potentiated contractions decreased to about 35% of baseline measurement of postextrasystolic potentiated contraction. In contrast, with reoxygenation, PESPs recovered quickly while resting contractions recovered gradually. Caffeine abolished the potentiation of post-extrasystolic contraction not only in normoxia but also in hypoxia. We speculate that calcium release from the sarcoplasmic reticulum (SR) is attributable to PESP for the most part, and that the trans-sarcolemmal calcium influx generally contributes to the steady-state tensions developed by continuous stimulations. In addition, it seems that PESP works in a ischemic heart to compensate for the decreased tension during hypoxia as a potentiation by a premature ventricular contraction. Trans-sarcolemmal calcium influx might be affected more easily than the SR calcium release, by a combination of hypoxia and the absence of glucose, that is, the sarcolemma may be more susceptible to hypoxic injury than the SR.

Animals↗
PubMed1989

The contribution of an extrasystole to postextrasystolic potentiation in papillary muscles of guinea pigs.

It is well known that a short rest period during the regular stimulation of isolated cardiac muscle induces a transient increase of subsequent twitch tension, although the mechanism of postextrasystolic potentiation (PESP) is still unclear. This paper is concerned with the contribution of an extrasystole to the PESP using isolated papillary muscle of guinea pigs. We have found that the length of the coupling interval of the extra-stimulation prior to the rest interval affected the degree of PESP in a coupling interval-dependent way at the same rest period, and the PESP of the same coupling ratio increased and decreased at the rest period was prolonged. Theophylline increased the strength of steady-state twitch tensions, whereas the dependency of PESP on a coupling ratio of extra-stimulation was removed and the PESP decreased with prolonged rest periods. The evidence suggests that the coupling ratio of extra-stimulation might vary the relative contributions of trans-sarcolemmal Ca influx and Ca release from the sarcoplasmic reticulum.

Animals↗
PubMed1989

[Thallium-201 myocardial perfusion imaging during transient coronary occlusion at the time of PTCA: comparison with stress imaging].

To evaluate myocardial perfusion during transient coronary arterial occlusion, thallium-201 was administered intravenously during percutaneous transluminal coronary angioplasty (PTCA) in 12 patients with effort angina, and the resulting perfusion images were compared with those of exercise stress obtained before PTCA. Thallium-201 was injected at the last inflation of an angioplastic balloon and occlusion was maintained for 60 to 90 sec. Three projections of planar images were obtained immediately after PTCA, using a portable gamma camera in an angiography room. These perfusion images obtained during PTCA and exercise were visually interpreted and compared. Myocardial perfusion defects due to the responsible vessel occlusion were observed at early imaging after PTCA, and were fully redistributed three hrs post injection. In 10 patients without angiographically imaged collateral vessels, there were no significant differences in perfusion between images during PTCA and during exercise. Two patients whose collaterals were observed during coronary angiography before PTCA had higher perfusion scores during PTCA than during exercise. We concluded that intravenous injection of thallium-201 during PTCA is a useful means for assessing alteration of myocardial perfusion due to transient coronary occlusion without increasing the risk of angioplastic procedures, and that it provides more precise information about the jeopardized myocardium, perfused by antegrade blood flow.

Angioplasty, Balloon↗
PubMed1989

[Ultrasonic tissue characterization by spectral analysis of myocardial textural pattern].

Based on the fact that ultrasonic myocardial textural patterns are more irregular in the pathological myocardium than in the normal, evaluation of the myocardial tissue character was attempted in vivo using spectral analysis. Parasternal left ventricular long-axis echocardiograms were obtained from five patients with old myocardial infarction diagnosed by history, electrocardiography and coronary angiography. These echocardiograms were transferred to an image analyzer and digitized (256 x 256 x 8). The waveforms of the gray-scale-changes from the normal myocardium showed periodicity in each 8-pixel cycle, but those from the infarcted myocardium did not. To quantify pattern changes in gray-scale values in the ultrasound beam direction, spectral analysis was performed by the maximum entropy method (MEM). There were four peaks in the MEM spectra both in the normal and infarcted myocardia, but there was a great significance in these patterns: with high, steep peaks in normal MEM spectra, and low, blunt peaks in infarcted ones. By discriminatory analysis of these four peak values, normalized by the whole spatial frequencies as multivariate, the misclassification rate was 4.8-22.7% in anteroseptal infarctions and 5.0-20.0% in posterior infarctions. Thus, spectral analysis of the myocardial textural pattern has advantages for analyzing routine echocardiograms without corrections by any absolute ultrasonic references. Furthermore, the misclassification rate is so low that we are able to characterize myocardial tissue.

Echocardiography↗
PubMed1989

[Effect of mexiletine on human atrial vulnerability].

The effect of mexiletine on human atrial vulnerability was investigated in 14 subjects (8 with paroxysmal atrial fibrillation, 2 with paroxysmal atrial tachycardia, 2 with ventricular tachycardia, 1 with sick sinus syndrome and 1 with Wolff-Parkinson-White syndrome). During the electrophysiologic study, after 8 consecutive stimuli (A1) were delivered through the electrode catheter positioned at high right atrium, premature stimulus (A2) was introduced, and following measurements were made; 1) Aw: atrial activity width of A1, 2) maximum atrial fragmentation (MAF): the longest atrial activity width of A2, which was expressed by the relative value against Aw, 3) fragmented atrial activity zone (FAZ): the zone of the coupling interval (A1A2) with the prolongation of the atrial activity width at A2 more than 150% against Aw, 4) conduction delay zone (CDZ): the zone of A1A2 with the prolongation more than 20 msec of the intraatrial conduction time at A2 from high right atrium to coronary sinus or low right atrium against the intraatrial conduction time at A1, and 5) right atrial effective refractory period (RAERP). These measurements were repeated after the intravenous administration of mexiletine (2 mg/kg/10 min). 3 cases (case 12, 13 and 14), whose FAZ and CDZ were 0 msec, were excluded from the following evaluation. Mexiletine showed little effect on Aw and RAERP, but significantly shortened MAF and FAZ (p less than 0.001 and p less than 0.05, respectively). CDZ were also reduced in 3 cases and remained unchanged in 6 cases, though no statistical difference of CDZ was recognized between before and after the administration of mexiletine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Swallowing-induced arrhythmia.

Deglutition tachyarrhythmia, first reported in 1926 by Sakai and Mori, is a rare clinical entity. Vagal reflex has been supposed to be responsible for the induction of the arrhythmia. We have recently studied a patient with swallowing-induced premature atrial contractions. Atropine sulfate and catecholamine infusion increased the frequency of the arrhythmia, while beta blockade suppressed it. It is suggested that the mechanism of the swallowing-induced arrhythmia might be related to a sympathetic reflex. As far as we know, there have been few reports in which the sympathetic reflex was proposed to be responsible for the arrhythmia.

Adult↗
PubMed1988

A case of left ventricular aneurysm of uncertain etiology presenting as ventricular tachycardia.

A case of a 59-year-old Asian male with several episodes of syncope and palpitation is reported. Electrophysiologic study disclosed that sustained ventricular tachycardia was induced by programmed electrical stimulation at the right ventricular apex. The electrogram in the left ventricular aneurysm showed delayed activities and the fastest depolarization. Entrainment was observed by faster pacing. Left ventriculography showed a large aneurysm and normal coronary arteries. Congenital left ventricular aneurysm is the most likely clinical diagnosis given the lack of past history of chest pain, myocarditis, cardiomyopathy, etc. Congenital aneurysm which presents as ventricular tachycardia is very rare, and has never been reported in an Asian. Medical management has thus far been successful.

Bundle-Branch Block↗
PubMed1988

Significance of serum thyrotropin and plasma dopamine concentration in the regulation of thyroid function in elderly subjects.

In our previous study, we observed a tendency towards an age-related increase in the serum thyrotropin (TSH) concentration. Regulatory mechanisms of TSH secretion in elderly subjects were studied. In 43 elderly subjects, serum TSH did not correlate significantly with serum T4, T3 free T4 or rT3. Further, those with increased TSH (greater than 5 mU/l, 9 subjects) did not overlap with those with low T3 (less than 0.92 nmol/1, 8 subjects). Increases in serum TSH were not associated with the presence of circulating anti-thyroid autoantibodies. A TRH test using a 500 micrograms single bolus injection was performed in 15 subjects. TSH response (basal: 1.92 +/- 1.42 (s.d.) mU/1, peak: 11.25 +/- 5.33 mU/1, sigma: 26.74 +/- 12.89 mU/1, respectively) did not differ significantly from that of younger subjects. T3 response after TRH varied greatly and a close correlation was observed between basal T3 and peak T3 (r = 0.86), and also between peak T3 and delta T3 (r = 0.81). A significant correlation was observed between sigma TSH and basal T3 (r = 0.60). Neither plasma cortisol, epinephrine nor norepinephrine concentrations showed any significant correlation with basal and TRH-stimulated TSH or T3 concentrations. However, the plasma dopamine concentration correlated significantly with sigma TSH (r = 0.60) and basal T3 (r = 0.52), respectively. In conclusion, the increase in serum TSH observed in elderly subjects was felt to represent a physiological adaptation to maintain serum T3. Low T3 subjects appear to have a disturbance in this mechanism, with decreased TSH and T3 response to TRH stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Effects of low dose L-triiodothyronine administration on mental, behavioural and thyroid states in elderly subjects.

Decreased serum T3 concentrations in elderly subjects and their possible relationship with the development of dementia have been indicated. To see the effects of a passive increase in the serum T3 concentration, low dose T3 administration was undertaken. Forty-four subjects from 65 to 93 years of age (average 81.0 +/- 7.8) were divided into 2 groups. The grade of dementia was determined by Hasegawa's dementia rating scale (DR score). In 22 subjects, 25 micrograms per day of T3 was administered for 4 W, while the control group was given a placebo. The DR score was measured before and immediately after the study. Changes in behaviour were monitored in a double-blind fashion. The administration of T3 induced a 0.65 nmol/l increase in serum T3 in 2 W and 0.36 nmol/l in 4 W. These T3 increases were not associated with significant changes in the DR score but 7 of 22 subjects showed apparent improvement in behaviour. TSH was suppressed to less than 1 mU/l in 2 W and then slightly increased by the 4th week, but T4, rT3 and fT4 all showed significant and progressive decreases. The DR score after T3 correlated significantly with the rT3/T4 ratio (before T3: -0.55, changes: +0.50) and also with changes in rT3 (r = 0.49). In conclusion, T3 administration to the elderly subjects was associated with behavioural improvement in some individuals, but the intellectual ability as assessed by the DR score in those with low T3 or elevated rT3 were hardly improved by passive T3 elevation.

Administration, Oral↗
PubMed1988

[Value of exercise echocardiography in evaluating left ventricular systolic function in mitral stenosis].

Exercise echocardiography was performed for 34 patients with mitral stenosis (MS) to evaluate left ventricular (LV) systolic function. The patients were categorized in three groups according to the work loads attained: Group I, 14 patients who attained 25 watts; Group II, 10 patients, 50 watts; and Group III, 10 patients, 75 watts. Among these groups, there were no statistical differences between the resting echocardiographic LV systolic function and their cardiac catheterization data. Resting LV end-diastolic and end-systolic dimensions (EDD and ESD) did not differ by group. During exercise, EDD and ESD decreased significantly in all groups, but ESD at the maximum exercise in Group I was greater than those of the other groups. The percent fractional shortening of the left ventricle (%FS) decreased significantly with exercise in Group I, while it increased significantly in the other groups. The mean velocity of circumferential fiber shortening (mean Vcf) increased significantly in all groups, but the extent was least in Group I. The exercise-induced changes in %FS (delta %FS) and mean Vcf (delta mean Vcf) correlated closely with exercise duration (r = 0.80, r = 0.73), but this was not the case in the mitral valve area. Postoperatively, exercise echocardiography was also performed for 14 patients with mitral stenosis; two of seven patients in Group I, four of five in Group II, and two in Group III showed significant improvement in exercise tolerance after surgery. However, the other six patients showed no change in their exercise tolerance. The former patients had positive values in delta %FS and more than 0.5 circ/sec in delta mean Vcf during pre-operative evaluations, while except one patient, those who did not improve had negative delta %FS values and less than 0.5 circ/sec in delta mean Vcf. It was concluded that the change in LV systolic function during exercise echocardiography reflects LV functional reserve in patients with MS, and provides valuable information for evaluating the severity of, indications for and benefits from surgery for MS.

Blood Pressure↗
PubMed1987

Devices external pulse generator: a reliable temporary pacemaker?

Two cases of malfunctioning APC (American Pacemaker Company) Devices pacemakers are reported. Two patients with sick sinus syndrome were temporarily paced using APC Devices pacemaker models EC 4542 and EV 4543 respectively, which showed transient increase (53% and 83% of the preset rate, respectively) in pacing rate. The sudden increase of the pacing rate might be the pacemaker's design to switch to fixed-rate pacing at nominally 25% higher than the selected rate in the presence of an excessive level of electrical interference. However, the increased rate was much faster than the interference rate. Great caution should be paid when APC Devices pacemaker is to be used.

Female↗
PubMed1987

Disappearance of blocking type thyrotropin binding inhibitor immunoglobulin (TBII) during thyroid and steroid medication in a patient with autoimmune thyroiditis.

A 55 year-old female had suffered from 3 consecutive diseases for a year. The diseases were ulcerative colitis, primary hypothyroidism and idiopathic thrombocytopenic purpura, and had been treated with L-thyroxine (50 micrograms daily) and betamethasone (0.5 to 1.5 mg daily). On examination, the thyroid gland was not palpable at all, thyroid 99 mTc pertechnetate uptake was 0%, and an echogram revealed the existence of an atrophic gland. Thyrotropin binding inhibitor immunoglobulin (TBII) in the serum was elevated to 58.0% and her IgG almost completely inhibited the in vitro cAMP increase due to bTSH. After 5 months TBII turned out to be negative and the inhibitory IgG activity was reduced significantly. The thyroid gland also became visible scintigraphically. Thyroid medication was then stopped. Four months after the cessation of thyroxine, she felt quite well and her thyroid functions remained within the normal ranges. Antibody to Yersinia enterocolitica was positive at a low titer (X20) in the early stages, but elevated reciprocally with the fall in TBII and finally reached X320. In conclusion, evidence of the disappearance of blocking type TBII from the serum was demonstrated for the first time. Steroid might have caused some favorable effects, and this clinical report indicates the possibility that remission of hypothyroidism due to blocking type TBII can be expected.

Antibodies, Bacterial↗
PubMed1985

Electrophysiological effects of bethanidine sulfate on guinea-pig papillary muscle.

Bethanidine, a chemical analog of bretylium, increased the plateau phase of the action potential of guinea-pig papillary muscle in 2.7 mM K+ Tyrode solution without changing other electrophysiological parameters. In 25 mM K+ Tyrode solution, the amplitude, duration and Vmax of the Ca2+-dependent action potential were increased in a dose-dependent manner by bethanidine. It is speculated that the mechanism of antiarrhythmic effect of bethanidine might be due to the prolongation of action potential by an increase of the slow inward current.

Action Potentials↗
PubMed1985

beta-Adrenoceptor agonist accelerates recovery from inactivation of calcium-dependent action potentials.

The voltage-activated Ca2+ channel in cardiac muscle plasma membranes is regulated by beta-adrenoceptor agonist, presumably by cyclic AMP-dependent phosphorylation of membrane proteins associated with this channel. In chick ventricle, we find that isoproterenol accelerates the recovery from inactivation of the maximum rate of rise (Vmax) of Ca2+-dependent action potentials without changing the steady-state inactivation of Vmax. These results confirm and extend those of others who found that beta-adrenoceptor agonists accelerated the repriming kinetics of bullfrog atrial Ca2+ current (iCa) channels. Patch clamp experiments showed that beta-adrenoceptor agonists change the kinetics of iCa channels so as to increase the probability that an iCa channel is available to open, primarily by reducing the intervals between bursts of channel openings. It is concluded that the altered kinetics of iCa channel repriming caused by beta-adrenoceptor agonist in multicellular preparations is consistent with the action of these drugs in increasing the probability of channel opening and the time spent in the open state.

Action Potentials↗