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Biomedical subjects

A Yamazato

Publications and source records attributed to A Yamazato.

At least 19 recordsLinked to original sources
PubMed1992

[The pitfalls in the clinical diagnosis of dissecting aortic aneurysm].

It is sometimes very difficult to diagnose dissecting aortic aneurysms (DAA), particularly in its early stage, due to manifold signs and symptoms. The purpose of this study is to clarify the reasons for such erroneous diagnoses. A total of 41 patients with DAA were referred to our hospitals for further examination and/or surgery from April 1986 to August 1989. In 18 of these patients, the diagnostic possibility of an underlying DAA was overlooked by the referring physicians. Among these 18 patients, 2 were mistakenly diagnosed as uncomplicated myocardial infarction (MI), one as pneumonia, 2 as cerebral infarction, 6 as acute abdominal disease, one as cholelithiasis, 5 as thrombosis of the lower extremities, and one as malignant metastasis to the pericardium. The following is the detail: In 2 cases thought to be uncomplicated MI, an expanding dissecting ascending aorta had crushed the lumen of the left coronary artery, causing MI, in turn, wasting clinical treatment and consuming precious time. In one case, enlargement of the descending aorta on the chest radiography was overlooked and the patient's symptoms were mistakenly attributed to pneumonia. In 2 cases in which symptoms of cerebral ischemia were thought to be attributed to cerebral thrombosis, the real cause turned out to be occlusion of the brachiocephalic artery following aortic dissection. Among 6 cases which were initially considered to have only acute abdominal disease, 3 presented with symptoms and signs of ileus, and their exploratory laparotomies yielded no positive findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

[Doppler echographic evaluation of pressure gradients of Björk-Shiley valve in the aortic position at rest and with exercise].

Pressure gradient across the Björk-Shiley (B-S) valve in the aortic position was assessed by Doppler echocardiography at rest and with exercise. There was close correlation between peak pressure gradient and area index which is a ratio of geometric orifice area (cm2) to body surface area (BSA) (m2). The correlation coefficient was -0.70 at rest and -0.86 with exercise. High peak pressure gradients with exercise were observed in the patients with 19 mm size (71 mmHg) and 21 mm size (107 mmHg). To avoid residual left ventricular outflow obstruction with exercise, it is considered advisable to use a #19 B-S valve in patients with BSA smaller than 1.1 m2, a #21 B-S valve in patients with BSA smaller than 1.4 m2, a #23 B-S valve in patients with BSA smaller than 1.8 m2, and a #25 B-S valve in patients with BSA smaller than 2.3 m2. If proper size of B-S valve cannot be inserted, aortic or aortic-mitral patch annuloplasty or the use of bileaflet valve are recommended as procedures of choice for small aortic annulus.

Aortic Valve↗
PubMed1991

[Clinical features of aortic dissection with early thrombosis of the false lumen].

There are cases of dissecting aortic aneurysm in which thrombotic formation occurs in the false lumen at an early stage, preventing dissection of the vessel wall and enlargement of the aneurysm. We studied such early thrombotic obliteration of false lumina in 12 (28.6%) of 42 patients with dissecting aortic aneurysm who underwent transesophageal two-dimensional echocardiography in the acute phase from June 1986 to October 1989. It was the first employment of a transesophageal approach at our hospital. In this study, we examined the clinical profiles of these patients as well as the usefulness of transesophageal two-dimensional echocardiography in establishing the diagnosis of dissecting aortic aneurysm and characterizing the disease. The patients were classified as Type I (2 patients) and Type III (10 patients; 6 Type IIIa and 4 Type IIIb) according to DeBakey's classification. The minimum and mean intervals from the onset of symptoms to transesophageal two-dimensional echocardiography were 1.5 hours and a mean of 38.2 hours, respectively. These results indicated that thrombotic obliteration of the false lumen had already occurred at a very early stage in some patients. The maximum diameter of the descending aorta was mean 37.6 mm with only 2 patients having that of 40 mm or more. Since left intrapleural hemorrhage was observed in these 2 patients (1 received emergent replacement of the descending aorta), enlargement of the aortic diameter may be indicative of unpredictable outcome, even in patients with early thrombotic obliteration of the false lumen. The long-term clinical course was favorable in all patients, including those who were treated surgically, over a mean follow-up period of 14.5 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

[Definitive myocardial blood flow evaluated by contrast echocardiography: experimental and A-C bypass flow studies].

We evaluated the feasibility of a new method for calculating definitive myocardial flow using contrast echocardiography in canine experiments and in patients who had undergone ACBG surgery. The principle for calculating flow was based on Kety-Schmidt method using time-intensity curve analysis between the epicardial and endocardial aspect. Inlet and outlet flows were hypothesized at the epicardium and endocardium, respectively. Analysis of time-contrast-intensity curves between the epicardium and endocardium, the difference of the area to the saturated point between epicardium and pericardium (A), and the saturated value (H) theoretically lead to the equation: Flow = 100 x (H/A) (Kety-Schmidt) in a 100-gram myocardium. No factors of intensity and time were included. Using this equation, the flow in 7 experimental canine and the flow of 9 patients who had ACBG surgery were compared to the electromagnetic flow. In the canine experiments, the left circumflex coronary artery was dissected free and was connected with contrast injector, a magnetic flowmeter and pneumatic occluder, proximal to distal in this order. Flow was controlled either by the occluder or drugs (papaverin and dipyridamole). Manually-agitated contrast media were injected rapidly (1 ml/2.5 sec), and M-mode echocardiographic recordings were densitometrically translated into time-intensity curves. Thirty-eight trials in 7 dogs showed close correlations (r = 0.901) between the electromagnetic flow and contrast echo flow. For the patients with ACBG, M-mode contrast echo recordings were made using transesophageal echo during the operations with contrast injections via the bypass grafts. Analysis of time-intensity curves was made and recorded in the same way as during the experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Problems in patients with use of a ventricular assist device].

The purpose of the present study was to review the results obtained in patients with a ventricular assist devices (VAD) in our hospital, and to discuss various problems concerning a VAD use, such as indications, right ventricular failure, and evaluation of cardiac function. Fourteen VADs were applied to 11 patients for left ventricular assist, including two for right ventricular assist and for one as biventricular assist with a VAD in the left and a biopump in the right. The clinical diagnoses of the patients were as follows: 10 ischemic heart disease, two valvular disease, one acute aortic dissection, and one corrected transposition of the great arteries. VADs were indicated in 11 patients because of difficulty in weaning from cardiopulmonary bypass (CPB), and in three patients because of cardiogenic shock after discontinuing CPB. Among the 14 patients, 11 had an effective VAD, six were successfully weaned from a VAD, and two survived. The VAD was ineffective due to uncontrollable bleeding and improper indications for the device, as in applying a one-sided heart assist when a biventricular assist was necessary. In spite of an effective VAD, five patients could not be weaned from VAD because of brain damage, sepsis, and hypoxia. After removing a VAD, four patients died; one due to mediastinitis, two due to respiratory failure, and one due to low output syndrome. All the four patients had renal failure followed by multi-organ failure finally, because of prolonged CPB time. The CPB time was shorter among the long survivors than in others. Cardiac function during assist and the weaning probability from a VAD were evaluated not only by the so-called on-off test, but also by transesophageal Doppler echocardiography. Ventricular wall motion and pulmonary venous flow pattern were analyzed by transesophageal Doppler echocardiography. The pattern of monophasic forward flow in the pulmonary vein was associated with reduced wall motion during deteriorated cardiac function, while the flow pattern became biphasic as cardiac function recovered. From these results, we concluded as follows: 1. Early decisions as to whether VAD is indicated are important. 2. A right VAD should be considered in cases with biventricular failure, during left ventricular assist, if right atrial pressures elevated more than 18 mmHg constantly. 3. The evaluation of cardiac function by transesophageal Doppler echocardiography is useful for making decisions as to wean patients from a VAD.

Adolescent↗
PubMed1990

[Transesophageal Doppler echocardiography in the diagnosis of atrial septal defect].

To assess the usefulness of transesophageal Doppler echocardiography (TEE) in diagnosing atrial septal defect (ASD), we studied eight cases with secundum type ASD, in which the diagnosis was confirmed by cardiac catheterization and surgery. In all cases, TEE provided clear images of the interatrial septum with its defect. Shunt flow through the defect was observed by color Doppler technique, and its velocity was measured using the FFT mode. In two cases, right-to-left shunt blood flow was detected. Two types of probes were used in this study, a lateral scanning probe and a longitudinal scanning probe. The scanning plane of the former was perpendicular to the axis of the probe, and that of the latter was parallel to it. The two probes facilitated the measurement of the two right-angled dimensions, with which we could calculate the defect area, assuming the defect to be an ellipse. The volume of a left-to-right shunt was obtained by multiplying the defect area by the integration of flow velocity against time. Shunt volume per cardiac cycle obtained by this method correlated well with that obtained by the Fick's method during cardiac catheterization. In six cases without a right-to-left shunt, the coefficient of correlation was 0.98, and in all eight cases it was reduced to 0.72. Thus, we concluded that TEE is useful for diagnosing and evaluating ASD.

Adolescent↗
PubMed1990

[Clinical usefulness of transesophageal Doppler echocardiography].

The usefulness of transesophageal Doppler echocardiography (TEE) was assessed in patients with various cardiovascular diseases including 15 patients with dissecting aortic aneurysm (DAA), two with thoracic aneurysm, 16 with ischemic heart disease and 14 with acquired valvular diseases. In dissecting aortic aneurysms, TEE provided clear images of the intimal flaps even in the aortic arch and descending aorta in which clear images could not be obtained by conventional external Doppler echocardiography. The entry site was detected in 11 of the 15 (73%) cases using TEE, but in only three of the 15 cases using conventional Doppler technique. In two cases of true aortic aneurysms, TEE provided clear images of the aneurysm in the descending thoracic aorta, which was discriminated precisely from DAA. In valvular disease, all four valves (aortic, pulmonary and atrio-ventricular valves) were easily observed without disturbance by any other tissues using a transesophageal approach. In addition, valve aneurysms in the posterior mitral leaflets were detected using TEE in two cases. In two cases of mitral stenosis, a thrombus was observed in the left atrial appendage. These findings were confirmed during surgery, but could not be obtained by the conventional external studies. In 16 cases, TEE was performed during aorto-coronary bypass surgery under general anesthesia. In two of these cases, left ventricular assist devices were applied after surgery. In these cases, where conventional Doppler echocardiography was not applicable, cardiac function could be monitored by TEE. Thus, TEE is useful not only in evaluating morphological function in the cardiovascular system but also in monitoring cardiac hemodynamics during and after heart surgery.

Adult↗
PubMed1989

Assessment of transesophageal Doppler echography in dissecting aortic aneurysm.

To assess the clinical value of transesophageal Doppler echography in the diagnosis of dissecting aortic aneurysm, both transesophageal and conventional echograms were performed in 22 cases of dissecting aortic aneurysm. Of the 22 patients, 17 underwent angiography; 8, X-ray computed tomography; 4, both; and 12, surgery. The performance of each method was assessed in the following four segments: A, ascending aorta; B, aortic arch; C, thoracic descending aorta; and D, upper abdominal aorta. The results by angiography were presumed to be correct. In the group of 17 patients who underwent angiography, the rate of correct detection of an intimal flap using the transesophageal approach was 100% in all four segments, significantly better than detection by the conventional approach (segment A, 65%; segment B, 47%; segment C, 35%; segment D, 53%) (p less than 0.01), and the rate of correct detection of the entry sites using the transesophageal approach was 100%, significantly better than that by conventional approach (42%) (p less than 0.05). X-ray computed tomography was not capable of detecting the site of entry in all cases. The presence of thrombus, aortic regurgitation and pericardial hemorrhage were all revealed clearly by the transesophageal approach, and the results were partly proved by other methods. In conclusion, transesophageal Doppler echography provides a rapid and accurate method of diagnosing and evaluating dissecting aortic aneurysm and permits prompt initiation of appropriate treatment.

Adult↗
PubMed1989

[A case report of emergency Bentall re-operation].

A 51-year-old male of Marfan syndrome with annuloarotic ectasia underwent the Bentall operation. One and a half months later, he suddenly fell into the left ventricular failure associated with lung edema. Echocardiogram revealed total occlusion of the graft and aortic valve detachment was suspected. An emergency operation was performed. The aortic valve was completely detached due to infectious endocarditis. As anastomosed portions of the proximal coronary arteries and distal aorta were intact, these rims of the old graft were reserved. A new composite graft was anastomosed distally to the above reserved graft rims and sutured proximally to the trimmed aortic valvular ring. The patient survived the re-operation despite many post-operative complications such as mediastinitis, colon bleeding, renal failure and severe hepatic dysfunction.

Aorta↗
PubMed1989

[Transesophageal Doppler echocardiography in the diagnosis of dissecting aortic aneurysm].

Transesophageal Doppler echocardiography (TEDE) was performed in three patients with proven or suspected DeBakey type I and type III aortic dissection. Case 1: A 66-year-old woman, with DeBakey type I aortic dissection. Clear images of a widened dissected aorta and an intimal flap were obtained in both the ascending and descending aorta, including the aortic arch. The site of an entry into the false lumen was identified by the defect of the intimal flap and the pulsatile entry flow through it. The reentry into the true lumen was also identified near the orifice of the celiac trunk. In this case, the observation was performed using this technique during the operation; i.e., replacement of the ascending aorta with an artificial graft. Case 2: A 77-year-old man, DeBakey type III aortic dissection. The study was performed after surgery which consisted of replacement of the descending aorta with an artificial graft. TEDE provided clear images of the artificial graft, the aorta, and their boundaries. The remaining intimal flap was clearly confirmed. Case 3: An 80-year-old man, DeBakey type III aortic dissection. In this case, though abdominal echography suggested aortic dissection, angiography and X-ray CT failed to facilitate the diagnosis. Only TEDE confirmed the diagnosis. The abnormal flow via the entry directing toward the false lumen was clearly demonstrated on the color Doppler images. We therefore conclude that TEDE is a useful and reliable means of diagnosing dissecting aortic aneurysm.

Aged↗
PubMed1986

Detection and evaluation of tricuspid regurgitation using a real-time, two-dimensional, color-coded, Doppler flow imaging system: comparison with contrast two-dimensional echocardiography and right ventriculography.

To detect and evaluate regurgitant flow in tricuspid regurgitation (TR) with a newly developed, realtime, 2-dimensional (2-D), color-coded, Doppler flow imaging system (Doppler 2-D echo), 27 patients (18 with suspected TR and 9 normal subjects) were examined and the findings were compared with those obtained using contrast 2-D echocardiography (contrast 2-D echo) and right ventriculography. In 16 of 18 patients with suspected TR, Doppler 2-D echo easily visualized the color-coded regurgitant flow in the right atrium and estimated the severity of TR from the distance of the visible TR jet. On the basis of the QRS synchronized appearance of contrast in the inferior vena cava by the subxiphoid approach or of the negative contrast effect above the tricuspid valve just after the contrast entered the right ventricle with its subsequent back-and-forth movements across the tricuspid valve, Doppler 2-D echo was more sensitive and specific in detecting TR (100% and 100%) than contrast 2-D echo (75% and 82% in the subxiphoid view, 56% and 100% in the 4-chamber view) when the fast Fourier transformation frequency analysis was used as the standard of TR, and it was more sensitive in detecting TR (85%) than contrast 2-D echo (69% in the subxiphoid approach, 46% in the 4-chamber view) when right ventriculography was used as the standard of TR. Additionally, the severity of TR as shown by Doppler 2-D echo correlated fairly well with that shown by right ventriculography. Thus, Doppler 2-D echo is clinically useful for detecting and evaluating TR.

Adult↗
PubMed1985

Detection of intracardiac shunt flow in atrial septal defect using a real-time two-dimensional color-coded Doppler flow imaging system and comparison with contrast two-dimensional echocardiography.

To evaluate the noninvasive detection of shunt flow using a newly developed real-time 2-dimensional color-coded Doppler flow imaging system (D-2DE), 20 patients were examined, including 10 with secundum atrial septal defect (ASD) and 10 control subjects. These results were compared with contrast 2-dimensional echocardiography (C-2DE). Doppler 2DE displayed the blood flow toward the transducer as red and the blood flow away from the transducer as blue in 8 shades, each shade adding green according to the degree of variance in Doppler frequency. In the patients with ASD, D-2DE clearly visualized left-to-right shunt flow in 7 of 10 patients. In 5 of these 7 patients, C-2DE showed a negative contrast effect in the same area of the right atrium. Thus, D-2DE increased the sensitivity over C-2DE for detecting left-to-right shunt flow (from 50% to 70%). However, the specificity was slightly less in D-2DE (90%) than C-2DE (100%). Doppler 2DE could not visualize right-to-left shunt flow in all patients with ASD, though C-2DE showed a positive contrast effect in the left-sided heart in 9 of 10 patients with ASD. Thus, D-2DE is clinically useful for detecting left-to-right shunt flow in patients with ASD.

Adolescent↗