Biomedical subjects

I Kubota

Publications and source records attributed to I Kubota.

At least 55 records · Page 3Linked to original sources

PubMed1996

Impaired hyperemic response of forearm vessels in patients with coronary artery disease. A non-invasive evaluation.

The blood flow velocity of the right brachial artery was measured noninvasively by pulsed Doppler flowmetry in 50 patients with angina pectoris. Reactive hyperemia was induced by a 2-minute occlusion of the artery by a tourniquet. We assessed the peak velocity ratio (PVR) and 50% recovery time (RT) which were defined as the ratio of maximal to baseline systolic peak velocity and as the interval from the resumption of arterial flow to 50% decline of the increased systolic peak velocity, respectively. Multiple regression analysis for determinants of PVR and 50% RT was performed with 7 variables which were age, sex, hypertension, diabetes mellitus, smoking, total cholesterol level, and the number of diseased coronary arteries. Multiple R was 0.649 (p < .01) for PVR and 0.682 (p < .01) for 50% RT. There were significant inverse correlations between PVR and the number of diseased vessels (t-value; -3.34), hypertension (-2.43) and smoking (-2.38). The 50% RT was inversely correlated with the number of diseased vessels (t-value; -4.45), feminine gender (-2.75) or smoking (-2.12). Stepwise regression analysis revealed that the number of diseased vessels was the only significant variable for the determination of PVR or 50% RT. An impairment of reactive hyperemia at the forearm vessel correlated with the severity of coronary artery disease in patients with angina pectoris. This finding suggests the presence of some identical mechanisms which are detrimental to both vascular beds. Observation of the hyperemic response at the brachial artery will provide a clue for noninvasive estimation of the extent of coronary artery disease.

Adult↗

PubMed1995

Diagnostic usefulness of activation-recovery interval for reciprocal ECG changes. Effects of regional myocardial cooling, warming, or coronary occlusion on epicardial electrograms in dogs.

The proximal left circumflex coronary artery (LCx) was cannulated and perfused with blood from the carotid artery in nine open-chest dogs. Perfused blood temperature was modulated by immersing a bypass tube in a temperature-controlled water tank. Two epicardial electrodes were placed, one at the LCx area and one at the left anterior descending coronary artery (LAD) area. The temperature of the autoperfused blood was set at 23 degrees C and was gradually elevated to 42 degrees C during 30 minutes. The QRS, ST-T, and QRST areas, and the activation-recovery interval of the electrode at the LCx area, changed unidirectionally in relation to elevation of the blood temperature. Although the QRS, ST-T, and QRST areas of the electrode at the LAD area changed in proportion to changes in the electrode at the LCx area, the activation-recovery interval of the electrode at the LAD area remained constant in all dogs. During 2-minute occlusion of the proximal LCx (n = 7), the activation-recovery interval of the electrode at the LAD area also remained constant despite the presence of reciprocal electrocardiographic changes. The activation-recovery interval is a useful index for defining whether a change in ST-T in a unipolar electrogram is due to a local electrophysiologic effect or a reciprocal effect.

Action Potentials↗

PubMed1995

Anomalous origin of the right coronary artery from the left ventricle in an adult.

A 64-year-old woman was referred to cardiac surgery because of aortic stenosis. At surgery, it was confirmed that the right coronary artery arose from the pars membranacea of the left ventricle 5 mm beneath the commissure between the right coronary and noncoronary cusps.

Aged↗

PubMed1995

Association of ACE gene polymorphisms with coronary artery disease in a northern area of Japan.

The insertion/deletion DNA polymorphism of the gene coding human angiotensin converting enzyme (ACE) was examined in 109 patients with coronary artery disease (CAD) and 93 non-coronary subjects (NCS) living in a northern part of Japan. The presence of risk factors including age, hypertension, hypercholesterolemia, tobacco use, diabetes mellitus and hyperuricemia were also examined. An insertion (I) / deletion (D) polymorphism of the ACE gene was determined by the polymerase chain reaction with oligonucleotide primers encompassing the polymorphic region in intron 16. The template DNA was isolated from peripheral blood leukocytes of patients. The frequency of the D-allele in NCS was 0.27, significantly lower than that reported in Caucasians or in Japanese living in the Osaka area. The frequency of the D-allele in patients with myocardial infarction (MI) and angina pectoris was 0.39 and was higher than that in NCS. The frequencies of genotypes DD, ID, and II were 17.8, 43.3 and 38.9%, respectively, in CAD except in young patients (below 40 years of age) with MI and AP groups, and 6.5, 40.9 and 52.7%, respectively in NCS (p < 0.05 between CAD and NCS). Young MI showed similar frequencies in ACE gene polymorphisms to those in NCS, a pattern which differed from that seen in subjects with CAD (p < 0.05). The numbers of risk factors did not alter the frequency of ACE gene genotype among patients with CAD, however, in normotensives, the odds ratio of DD-genotype was significantly increased to 3.4. Accordingly, ACE gene polymorphism may be associated with morbidity from CAD in Japanese living in northern Japan as has been noted in Caucasians, despite the lower frequencies of the D-allele in the Japanese population.

Adult↗

PubMed1995

[Spatial distribution of high-frequency components in the terminal QRS complex in patients with ventricular tachycardia and previous myocardial infarction--comparison of late potential map and spectral analysis].

It is clinically important to predict the ventricular tachycardia (VT) for the prognosis in patients with previous myocardial infarction. Low-amplitude high-frequency components observed at the end of QRS complex, termed "late potentials" are associated with VT. The use of signal-averaged body surface mapping technique enabled us to study spatial distributions of high-frequency components in the QRS terminal portion. In this paper, we investigated body surface distributions of high-frequency components in the terminal QRS complex, compared with late potential map and spectral analysis. Signal-averaged body surface mapping will provide new electrical information regarding understanding of the high-frequency components in the QRS complex.

Body Surface Potential Mapping↗

PubMed1995

[Ultrasonographic diagnosis of athero- and arterio-sclerosis].

Modalities to depict atherosclerotic lesion, have recently been rich in approaches, such as angiography, computed tomography, ultrasonography, radionuclide imaging and magnetic resonance imaging. Although the angiography is still one of the gold standards for diagnosing athero- and arteriosclerotic changes, recent developments in interventional catheterization and medical treatments necessitate the detailed characterization of the vascular wall. High-frequency ultrasonography now expands the observation toward the structure and composition of the vascular wall which can not be obtained in angiography. The higher the frequency of ultrasound is, the better the resolution of the echo imaging improves. However, the adequate depth for echo observation from the probe becomes narrower with the increase of the probe frequency. Accordingly, we have to choose an adequate approach for the vessel of interest. For example, transesophageal echocardiography is useful to evaluate the atherosclerotic changes of the descending aorta. Peripheral ultrasonography is useful for the superficial arteries, including carotid arteries, femoral arteries and branchial arteries. The advantages of the peripheral body surface approach are non-invasiveness and repeatability. Intravascular ultrasonography requires invasive technique, but it provides novel information regarding the presence and the extent of atherosclerosis and its characterization such as calcification. Intravascular ultrasonography is a necessary modality for evaluating the effect of the directional coronary atherectomy.

Arteriosclerosis↗

PubMed1995

[Spectral analysis of body surface ECG maps].

A signal-averaging technique was applied to 60-lead epicardial mapping in dogs and 87-lead body surface mapping in patients with anterior myocardial infarction. By means of fast Fourier transform and inverse fast Fourier transform analysis, we obtained the reconstructed signals of several frequency ranges in the QRS complex. We showed the effects of myocardial infarction on QRS spectral changes and discussed the usefulness of this method for evaluating ventricular tachycardia and left ventricular function after myocardial infarction.

Animals↗

PubMed1994

Relation of principal components of ECG maps to loci of wall motion abnormality in old myocardial infarction.

The purpose of this study was to examine the correlation between body surface potential distribution and the extent of abnormally contracting segments (ACS) of the left ventricle in patients with old myocardial infarction (MI). Body surface potential distribution was quantitatively analyzed using principal component analysis. The first six principal components were extracted from data set obtained from both 25 normal subjects and 100 patients. The z scores (principal component weights) were calculated in a time domain at every 4 or 8 ms in another 81 patients with previous MI. In anterior MI, the second z scores on T wave and the fourth z scores on QRS complex were significantly lower in the presence than in the absence of ACS at the lateral wall. In inferior MI, the first z scores on QRS complex, the second on T wave, and the third on both Q and T represented significant differences between the presence and the absence of ACS at the posterior wall. Minute differences in the extent of ACS were sensitively and noninvasively detected on z scores of principal components.

Adolescent↗

PubMed1994

The significance of right ventricular ischemia in reflex bradycardia in humans.

Heart rates (HR) were measured before (control HR) and after (ischemic HR) balloon inflation during percutaneous transluminal coronary angioplasty in 96 patients with effort angina pectoris. The delta HR, defined as (ischemic HR-control HR), in the right coronary artery occlusion was significantly smaller than that in the left anterior descending artery or left circumflex artery occlusion. Among right coronary artery occlusions the delta HR in segment 1 occlusion was significantly smaller than that in segment 2 or segment 3 occlusion. It is suggested that the ischemia of the right ventricle plays an important role in producing a reflex bradycardic response in humans.

Angina Pectoris↗

PubMed1994