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Biomedical subjects

I Kawabori

Publications and source records attributed to I Kawabori.

At least 19 recordsLinked to original sources
PubMed1992

Functional implications of the pulmonary microcirculation. An update.

The microscopic anatomy of the pulmonary circulation was reviewed, comparing the evidence for two competing models, the sheet-and-post paradigm and the tubular paradigm. Implications of the two paradigms were analyzed for function, including flow, recruitment, distension, and diffusion. We conclude that the pulmonary microcirculation is not essentially different from the systemic microcirculation except that two layers of tubular capillaries are arranged on a central layer of connective tissue, the alveolar wall. We find no morphologic basis or theoretic advantage for the sheet-and-post concept.

Animals↗
PubMed1986

Doppler pressure gradient estimation in children. Accuracy, effect of activity and exercise, and the need for sedation during examination.

Noninvasive estimation of pressure drop has been shown to be an accurate and useful application of Doppler echocardiography. Most accuracy series have used patient-sedated catheterization gradient measurements as the standard of reference. Doppler gradient estimates, however, are commonly made without sedation of the patient when hemodynamics may differ from those present at catheterization. We questioned whether "unsedated" Doppler gradient estimates would correlate in a useful way with "sedated" catheter measurements, Doppler gradient estimates would vary with patient activity, exercise or crying, and Doppler gradient estimates made using chloral hydrate sedation would prove useful in predicting sedated catheter measurements. Twenty-five infants and children were examined under conditions 1 and 2 above, and 20 under condition 3. Sedated Doppler estimates, performed at the time of catheterization corresponded closely with catheter measurements (r = 0.97, SEE = 4.8), confirming the accuracy of the Doppler method. Gradients estimated by Doppler without sedation, or with activity, correlated poorly with sedated catheter measurements (SEE = 16.2, SEE = 34.9, respectively). Use of chloral hydrate sedation for Doppler estimates resulted in good correlation with subsequent sedated catheter measurements. The results demonstrate marked increases in noninvasive Doppler pressure gradient estimates under conditions other than sedation. Clinicians tend to think in terms of sedated catheter gradients as the standard of reference for evaluation of severity and need for surgery. Ultrasonic data can only be used if Doppler estimates are performed under similar physiologic conditions; in children this requires sedation.

Adolescent↗
PubMed1979

The significance of carotid bruits in children: transmitted murmur or vascular origin, studies by pulsed Doppler ultrasound.

Forty-four youngsters with precordial murmurs and carotid bruits were evaluated clinically and independently, using pulsed Doppler ultrasound. The precordial murmur was evaluated with M-mode echocardiography combined with Doppler flow evaluation, and the carotid bruit was evaluated with peripheral vascular sector scan with Doppler flow evaluation. These ultrasonic techniques can identify abnormal blood flow at anatomic sites such as the aortic valve and in the carotid arteries. The patients had no symptoms and their condition, except for six, was mild enough that catheterization was not indicated. The clinical diagnosis of aortic stenosis was made in 30 children, and nine were thought to have no heart disease. On the basis of the ultrasonic examinations, 28 patients were diagnosed as having aortic stenosis and seven subjects had no intracardiac turbulence. However, there was disagreement in 14 instances; four of the six clinical "normals" were found to have aortic stenosis by pulsed Doppler echocardiography; six patients diagnosed as having mild aortic stenosis on a clinical basis were found to have no aortic abnormality. The results confirm that aortic stenosis usually presents as a murmur maximal in the aortic area, which is associated with a carotid bruit. Unfortunately, in at least one-fourth of the cases the murmur was not maximal at the aortic area, and a carotid bruit was found in several normal subjects. Since the consequences of over- or under-diagnosis of aortic stenosis are substantial, careful thought should be given to the differential diagnosis, and if possible, pulsed Doppler echocardiography should be utilized for a definitive statement of aortic valve-induced turbulence.

Adolescent↗
PubMed1979

Pulsed Doppler echocardiographic detection of total anomalous pulmonary venous return: resolution of left atrial line.

During precatheterization M mode echocardiographic examination, 33 infants were identified as having findings including right ventricular enlargement and presence of a line within the left atrial portion of the M mode tracing suggesting the possibility of cor triatiatum or total anomalous pulmonary venous return. Pulsed Doppler echocardiography was used to sample blood characteristics on either side of the left atrial line to determine which line was artifactual and which was indicative of an important structure. Five patients whose blood flow characteristics were different on either side of the left atrial line were subsequently proved to have total anomalous pulmonary venous return at cardiac catheterization. In the remaining infants blood flow characteristics were identical on either side of the line, and catheterization excluded total anomalous pulmonary venous return and cor triatriatum. In all patients who had total anomalous pulmonary venous return, drainage involved a persistent left superior vena cava, and this vascular structure was identified by pulsed Doppler examination from the suprasternal notch. Pulsed Doppler echocardiography appears to be a useful technique for resolution of left atrial lines found on M mode echocardiography.

Cardiac Catheterization↗
PubMed1979

Noninvasive detection of pulmonary hypertension in patent ductus arteriosus by pulsed Doppler echocardiography.

Twenty-five patients with proven patent ductus arteriosus were examined by pulsed Doppler echocardiography (PDE) before invasive assessment. Ten patients had normal pulmonary artery pressures, and by PDE, pandiastolic ductal flow. Fifteen patients had elevation of mean pulmonary artery pressure, and by PDE, all had abbreviations of diastolic ductal flow. PDE correctly distinguished between patients with normal pressure and those with evidence of pulmonary hypertension; the ECG did not allow such differentiation. Detection by PDE of pulmonary hypertension complicating patent ductus arteriosus appears to be clinically useful.

Blood Pressure↗
PubMed1978

Diagnosis of ventricular septal defect by pulsed Doppler echocardiography. Sensitivity, specificity and limitations.

The M-mode echocardiographic findings of ventricular septal defect (VSD) are nonspecific. A specific pulsed Doppler echocardiographic (PDE) diagnosis of VSD can be made by following the turbulent VSD jet through the septum. To assess the sensitivity, specificity and limitations of PDE diagnosis of VSD, 105 children undergoing cardiac catheterization were examined by PDE. These children had a variety of cardiac defects, and a PDE diagnosis of VSD was made in 46/51 (90%) who had VSD proven at catheterization. There was one false positive PDE diagnosis of VSD, for a specificity of 98%. Factors influencing the ability to diagnose VSD by PDE include the location of the defect, level of pulmonary vascular resistance and direction of blood flow through the VSD. The presence of additional defects did not interfere with PDE diagnosis of VSD. The PDE detection of additional defects may identify situations where M-mode echocardiographic estimation of dimensions may not be indicative of the size of VSD shunt.

Adolescent↗
PubMed1977

Surgical correction in infancy to reduce mortality in transposition of the great arteries.

The mortality for infants with transposition of the great arteries (TGA) prior to the introduction of medical and surgical septostomy was over 80% by 6 months of age. The mortality has fallen recently, due to balloon atrial septostomy (BAS), but still exceeds 25% by 6 months of age in major centers. The cumulative mortality rises to 40% by 1 year of age with or without additional surgical atrial septectomy. In our center, 12 patients with an average age of 3 months were operated on for interatrial baffle correction of their TGA under surface-induced deep hypothermia. BAS had been done preliminarily in those patients without an adequate atrial communication. Ten of these 12 patients (83%) survived. These patients have been followed up from one month to eight years with an average follow-up of over four years. Surgical correction during infancy offers a better survival rate for infants with TGA than does medical management, with or without palliative surgery.

Ductus Arteriosus, Patent↗
PubMed1976

Incidence of exercise-induced asthma in children.

The incidence of exercise-induced asthma (EIA) was studied in 134 asthmatic and 102 nonasthmatic atopic children and compared to that in 56 nonatopic children. Pulmonary function tests measuring forced vital capacity (FVC) and 1-sec forced expiratory volume (FEV1) were performed on each child prior to and serially for 20 min following free running exercise. The incidences of EIA among the asthmatic and atopic nonasthmatic children were 63% and 41%, respectively. This phenomenon is widespread among allergic children and cannot be accurately predicted from the history. A simple and easily performed outpatient procedure is described for the diagnosis of EIA.

Adolescent↗
PubMed1975

Hypoxic apnea and gasping.

We have tested the hypothesis that severe lypoxia causes apnea, regardless of the arterial CO2 and pH, and that extreme hypoxia causes gasping. Acute experiments with airway occlusion and with low inspired oxygen (FIo2) were performed on anesthetized adult dogs and monkeys. Arterial oxygen saturation was recorded continuously with fiberoptic oximetry, and Pco2 by an electrode catheter. In addition, blood samples were obtained for Po2, Pco2, and pH. Apnea was induced regularly when the Pao2 fell below 10 torr, whether the Paco2 was high with asphyxia (63 torr) or low (26 torr) with low FIo2. Similarly, the Pao2 at apnea was the same whether the pH was 7.17 with asphyxic hypoxia or 7.46 with hypoxic hypoxia. Gasping occurred at even lower Pao2 (below 5 torr) after 1 or 2 min of apnea. Gasping promptly restored the Pao2 to levels of moderate hypoxia (over 30 torr) which permitted resumption of regular respiration, with gradual elimination of the gasping. Fetal monkeys at term were studied in a similar manner from the moment of cord clamping. Their blood gases with apnea were quite similar to adult values in the narrow range of Pao2 and the wide range of Paco2 and pH. In the fetus, gasping was less immediately effective in improving arterial oxygen, but more persistent than in the adult. Regular respirations would not develop in the absence of oxygen in either the fetus or adult animal.

Acid-Base Equilibrium↗
PubMed1975

Rheumatic mitral regurgitation. The case for annuloplasty in the pediatric age group.

Eight youngsters (five female, three male, ages 10 to 19 years, mean 15 years) with isolated severe rheumatic mitral regurgitation have been subjected to mitral annuloplasty because of limiting symptoms and prominent ECG and X-ray changes. They have been followed for up to 11 years (mean 3.7 years), and 7 have had excellent results. An early (1961) patient had a small annulus and was not a favorable candidate; he had only transient improvement. Seven are greatly improved, have decreased cardiac size (often dramatic), and have improved ECG's. One has undergone successful pregnancy, and none has been limited in activities. The extent and duration of improvement, lack of mortality, and resumption of normal activities by these youngsters indicate surgical success. The essence of childhood and youth is activity and the future life span hopefully long; hence, annuloplasty would appear to be the procedure of choice for severe rheumatic mitral regurgitation in the pediatric age group, avoiding the usual need for anticoagulation and uncertain long-term results associated with mitral valve replacement.

Adolescent↗