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Biomedical subjects

I Yada

Publications and source records attributed to I Yada.

At least 91 records · Page 5Linked to original sources
PubMed1993

Measurement of myocardial blood flow in coronary artery bypass surgery.

It is now possible experimentally to measure myocardial blood flow of the beating heart using a helium-neon (He-Ne) laser Doppler flowmeter. A myocardial probe was redesigned to reduce its size and weight, and a method devised of fixing the probe to the beating cardiac surface to allow its clinical application. This modified laser flowmeter was used on 36 patients with ischaemic heart disease to measure myocardial blood flow before and after revascularization. Flow was measured in the right and left ventricles while patients were in a haemodynamically stable state as determined by electrocardiography, heart rate, blood pressure and double product (heart rate x systolic blood pressure). No significant difference was found between the mean(s.e.m.) preoperative and postoperative flow volume at the anterior wall of the right ventricle (77(15) versus 81 (12)ml/min per 100 g), which did not undergo revascularization, but mean(s.e.m.) myocardial blood flow at the ischaemic left ventricle increased significantly (from 68(15) to 88(13) ml/min per 100 g; P < 0.01). There was also no significant difference between preoperative and postoperative values of haemodynamic parameters of coronary blood flow. In conclusion, a means to measure myocardial blood flow with He-Ne laser Doppler flowmetry has been devised which shows coronary artery bypass grafting to increase myocardial blood flow in the ischaemic myocardium.

Adolescent↗
PubMed1992

Hematological problems during the use of cardiac assist devices: clinical experiences in Japan.

Hematological changes occurring during use of left ventricular assist devices (LVADs) were evaluated in 3 patients suffering from postcardiotomy cardiogenic shock. LVAD treatment ranged from 6 to 9 days. During the procedure, no anticoagulants were used in the first two cases, while in the third case, a protease-inhibiting agent, nafamostat mesilate (FUT-175), was used. In the first two cases without any anticoagulants, fibrinopeptide A (FPA) and thrombin-antithrombin III complex (TAT) increased markedly over the course of LVAD treatment, suggesting the excessive activation of the coagulatory system. The fibrinolytic system also became activated during LVAD treatment as was indicated by a marked increase in FDP-D-dimer and alpha 2 plasmin inhibitor-plasmin complex (PIC). Continual decreases observed in Factor XII and prekallikrein indicate that the coagulofibrinolytic activation occurring during LVAD treatment is presumably the result of contact activation of these factors due to interaction of blood with the internal surface of the LVAD. In the third case with FUT-175, both coagulation and fibrinolysis were successfully maintained at minimum levels as was demonstrated by the extremely low levels of these molecular markers. There was also no significant consumption of any contact factors. FUT-175 looks promising as an anticoagulant during the use of cardiac assist devices.

Aged↗
PubMed1992

[Left atrial myxomas: clinical characteristics, evaluation and considerations in classifying tumors].

Eleven patients underwent surgical excision for left atrial myxomas. Clinical symptoms, coronary angiographic findings and operative procedures were evaluated. Myxomas were classified into two types based on macroscopical findings, and clinical characteristics of these two types were analyzed. Seven cases (64%) classified as "lobular-type myxomas" were seen as lobulated, gelatinous and fragile. Four cases (36%) were classified as "round-type myxomas" were round and elastic soft. Primary symptoms included dyspnea on exertion in five cases (45%) and neurological disturbances in six cases (55%). Brain emboli were found in four patients by CT scan, and were classified as lobular-type myxomas. These eleven myxomas successfully removed in all cases. Four of these myxomas, which were pedunculated with fine fibrous stalks, were shaved along the base at the atrial septum or free wall. Others were excised completely along with a portion of the adjacent septum. Microscopic examination of the operative specimens revealed that two lobular-type myxomas with broad-based attachment to left atrial septum had invaded the atrial septum. All patients are doing well and have had no signs of myxoma recurrence at postoperative periods ranging from 10 months to 12 years (mean follow-up 5.3 years). Seven patients underwent selective coronary angiography due to a diagnosis of a coronary artery disease. All coronary angiograms were normal in all cases. In five (71%) of these seven, abnormally dilated atrial branches were seen as supplying the tumor. In two cases with round-type myxomas, neovascularity was evident and was made up of clusters of tortuous vessels with tumor blush.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

[Reconstructive surgery for mitral regurgitation caused by degenerative disease--indications for expansion and early clinical outcomes].

Between January 1983 and June 1990, there were 48 patients who underwent surgery for mitral regurgitation due to degenerative diseases. Among these, 20 patients received mitral valve repair. Overall operative mortality was 5% for patients who underwent valve repair, and 7.1% for those who underwent valve replacement. We standardized a maneuver for valve repair in August 1988 in an attempt to expand its indications. There were 35 patients who underwent surgery prior to that date (group 1), and 13 patients after that date (group 2). There were nine patients (25.7%) in group 1 and 2 patients (84.6%) in group 2 who underwent valve repair. Among these, one patient (11%) in group 1 died within 30 days after the operation, but there were no surgical deaths for any patients in group 2. In addition, one patient (11%) in group 1 and one (9%) in group 2 required another operation for valve replacement. Doppler echocardiographic studies performed postoperatively in 18 patients who had undergone valve repair showed that 13 (72.2%) had no regurgitation, 4 (22.2%) had trivial regurgitation, and 1 (5.6%) had mild regurgitation. Postoperative valve area as determined by continuous-wave Doppler echocardiography was 3.7 +/- 1.1 cm2 (mean +/- SD) for patients who had undergone reconstruction and 3.1 +/- 0.7 cm2 for those who had undergone replacement.

Adolescent↗
PubMed1992

[Clinical evaluation of treatment for prosthetic valve endocarditis and analysis of factors affecting outcome of surgical therapy].

We analyzed the outcome for 18 patients with prosthetic valve endocarditis (PVE) treated between 1965 and 1990, 17 of whom had undergone valve replacement with mechanical prosthetic valves and one of whom had a bioprosthesis. Two patients developed infection within 60 days after surgery, and 16 thereafter. Fifteen patients received combined medical and surgical therapy and three medical therapy. In 14 patients, surgery had been performed during active infection. Mortality rate of those who had received combined medical and surgical therapy was 27%, and that of those who had received medical therapy was 67%. At operation, para-annular abscess was around the mitral prosthesis was found in three patients and around the aortic prosthesis in eight. Seven patients required reoperation for postoperative paravalvular leakage, in six, para-annular abscess had been found at the operation for PVE, and in one para-annular abscess had been noted. One patient who had undergone reoperation had developed reinfection after the first surgery and died due to multiple organ failure after the second operation (Danielson's translocation technique). In one patient who had complete loss of supporting tissue because of severe para-annular abscess, we had performed aortic valve replacement by implanting the aortic valve prosthesis into the left ventricle with Dacron felt-supported sutures placed in the mitral annulus and the muscles of the left ventricular outflow tract. This patient showed no postoperative infection or no paravalvular leakage.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Laser measurement of myocardial blood flow.

A He-Ne laser flowmeter (wavelength: 632.8 nm, power: 2 mW) has already been used to measure blood flow in skin, muscle, and mucosa. However, the application of this flowmeter for the beating heart has been left undeveloped due to its difficulty. For the purpose of establishment of the laser measurement of myocardial blood flow, we redesigned a flow probe to be small and light and used a connecting paste to support the subepicardial flow probe. After resolving many obstacles, the noninvasive and real-time blood flow measurement of the beating heart was made possible. The flow volume in subendocardial myocardium was greater than the volume in subepicardial myocardium, and the average ratio of subendocardial flow to subepicardial flow was 1.62 +/- 0.21.

Animals↗
PubMed1991

The enhancement of myocardial protection through an acalcemic storage solution containing nicardipine, a potent calcium channel blocker. A basic study using rat ventricular myocytes.

Adult rat ventricular myocytes were used as a model system for investigating the direct effects of nicardipine, a potent calcium-channel blocker, on preservation of the heart during periods of simple cold storage. Cells were stored at 4 degrees C for 24 hr with an acalcemic storage solution. The superfusate then was exchanged with hypoxic Tyrode solution (1.8 mmol/L CaCl2). After 2 hr of hypoxia at 20 degrees C, cells were reoxygenated and simultaneously warmed to 37 degrees C. The addition of nicardipine to both the storage solution and Tyrode solution resulted in the highest percentage of viable cells (70.5%). Using either the storage solution or Tyrode solution containing the compound, the percentages of viable myocytes were 51.9% and 52.2%, respectively. In the absence of the drug in either solution, the percentage was 38.0%. The effect of diltiazem, another potent calcium-channel blocker, was examined using the same experimental procedure. The addition of diltiazem to Tyrode solution elevated the viability of ventricular myocytes, but addition to the storage solution showed no cardioprotective effect. Moreover, the addition of 8-bromo cyclic GMP to the storage solution resulted in a cardioprotective effect. These results suggested that nicardipine exerts a direct effect on myocardial protection in hypothermic and acalcemic storage solution and that the pharmacological effect of nicardipine depends on a mechanism other than its calcium-channel blocking action.

Animals↗
PubMed1991

Hemostatic alterations caused by ventricular assist devices for postcardiotomy heart failure.

The hemostatic alterations in two adult patients who were supported by left ventricular assist devices (LVADs) because of postcardiotomy heart failure were evaluated. In both patients, fibrinopeptide A and thrombin-antithrombin III complex increased markedly during the first several days, and thereafter decreased moderately but remained above normal over the entire procedure. Furthermore, fibrinopeptide B beta 15-42 and alpha 2 plasmin inhibitor-plasmin complex were also markedly increased over the entire course of LVAD treatment. These data show that the LVAD system strongly activates both the coagulation and the fibrinolytic system, even when thromboembolic or bleeding complications are not clinically evident. Furthermore, the decrease in physiological coagulation inhibitors, especially protein C, indicates that these factors are activated and consumed during LVAD treatment. Because protein C is important in regulating the coagulation cascade during LVAD treatment, exhaustion of this system might result in thromboembolic complications during LVAD treatment.

Aged↗
PubMed1991

[Surgical repair of ischemic mitral regurgitation].

We studied surgical results of 14 cases of ischemic mitral regurgitation. There was no surgical death in 10 cases with left ventricular aneurysm, and their clinical symptoms improved except 3 with the combined operation of left ventricular aneurysmectomy, mitral annuloplasty and bypass grafting. The range of the abnormal contracting segment significantly decreased after surgery except in 3 cases in whom clinical status was not improved. Three of 4 cases which underwent bypass grafting and mitral annulo-valvuloplasty survived, but one of them died of graft-versus-host disease. In the three survived cases, severe mitral regurgitation disappeared. We have concluded as follows: In cases of left ventricular aneurysm, a sufficient aneurysmal resection is very important to control the mitral regurgitation, and the additional procedures of mitral annuloplasty and bypass grafting are essential. The mitral valve replacement is recommended in case of the complete disruption of the papillary muscle. Mitral valvuloplasty combined with annuloplasty is suitable to control the regurgitation in the regional mitral prolapse due to the torn chordae.

Adult↗
PubMed1991

[Mitral prosthetic valve endocarditis diagnosed by transesophageal echocardiography--a surgical case report].

The patient was a 39-year-old female who had undergone mitral valve replacement 2 years previously. Staphylococcus epidermidis was detected on blood culture. Transesophageal echocardiography revealed vegetation attached to the left atrial site of the mitral prosthesis, whereas precordial echocardiography did not reveal any abnormal echo structure. The patient was performed an emergency operation, during which the echocardiographic finding was confirmed. We conclude that performance of transesophageal echocardiography is useful when clinical features suggest prosthetic valve endocarditis.

Adolescent↗
PubMed1990

[Evaluation of aortocoronary bypass operation using a He-Ne laser flowmeter--comparison between internal mammary artery grafts and saphenous vein grafts].

It was very difficult to measure myocardial blood flow in clinical cases. Recently, a He-Ne laser doppler flowmeter was developed, and we made it possible to measure the pre-and post-operative myocardial blood flow in cases of coronary artery bypass grafting (CABG). We applied a laser flowmeter to 30 cases of bypass grafting to the left anterior descending coronary artery (18 cases with IMAG and 12 cases with SVG). The preoperative myocardial blood flow at the right ventricular anterior wall was 77 +/- 15 ml/min/100 gr, and the postoperative flow at the same point was 81 +/- 12 ml/min/100 gr. There was no significant change between the pre-operative value and the postoperative one. Myocardial blood flow at the left ventricular anterior wall in SVG group significantly increased from the preoperative value of 58 +/- 11 ml/min/100 gr to the postoperative value of 86 +/- 9 ml/min/100 gr (p less than 0.001). In IMAG group, myocardial blood flow at the left ventricular anterior wall similarly increased from 73 +/- 14 ml/min/100 gr to 83 +/- 15 ml/min/100 gr (p less than 0.01). The postoperative value of IMAG group was almost equal to the value of SVG group. The increased rate of myocardial blood flow at the left ventricular anterior wall was 52 +/- 32% in SVG group and 18 +/- 12% in IMAG group. These rates were obviously distinguished from the increased rate at the right ventricular anterior wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Studies on so-called "postoperative erythroderma": report of four cases].

"Postoperative erythroderma", the pathogenesis of this disease have solved as graft-versus-host disease (GVHD) due to blood transfusion, is fatal and impossible to cure for the time being. Therefore the prevention against the disease is very important. One woman and three men who underwent an operation and blood transfusion at our department died of this disease. They fell into high fever on 11-13 days, erythroderma on 12-16 days, liver dysfunction on 14 days, and leukocytopenia on 17-19 days, after surgery and transfusion. Eventually, they all suffered from thrombocytopenia, diarrhea, renal dysfunction, and sepsis which led to death. The clinical course, macroscopic and microscopic findings of them coincided with those of GVHD. Since 1989, we have tried following methods for prevention of postoperative erythroderma: Reducing blood transfusion, especially fresh blood and fresh thrombocyte plasma, by using predeposited autologous blood, autologous washed erythrocytes collected from the operative area before and after extracorporeal circulation (ECC), concentrated residual blood from the ECC using a hemoconcentrater, and 1,500 rad of cobalt-irradiation of fresh blood, fresh thrombocyte plasma, and blood collected within 7 days prior to the transfusion. Postoperative erythroderma has not been experienced by introduction of these methods since 1989.

Aged↗