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Biomedical subjects

H Koyanagi

Publications and source records attributed to H Koyanagi.

At least 145 records · Page 8Linked to original sources
PubMed1996

Effects of smaller physical size on complex arterial grafting in coronary artery operations.

BACKGROUND: The trend in coronary artery bypass grafting is for a gradual transition to the more extensive use of arterial grafts. This study was designed to investigate the effects of patient body size on complex arterial grafting in coronary artery bypass procedures. METHODS: Four hundred forty-five patients who underwent coronary artery bypass grafting with two or more distal anastomoses using arterial grafts were divided into two groups according to body surface area: group A (n = 114), 1.60 m2 or less; and group B (n = 331), greater than 1.60 m2. Preoperative patient characteristics and early and long-term results were compared between the groups. RESULTS: The prevalence of female sex (27% in group A versus 0.9% in group B; p < 0.0001) and age (62.7 +/- 8.1 years in group A versus 58.9 +/- 7.0 years in group B; p < 0.001) were significantly different. However, the prevalence of previous myocardial infarction and of left ventricular dysfunction and the extent of coronary artery disease were not significantly different. Three patients (2.6%) in group A and 3 patients (0.9%) in group B died within 30 days of operation (p = 0.18). The 1-month patency rate of arterial grafts was not significantly different (98.7% versus 96.7%; p = 0.16), but that of venous grafts was significantly lower in group A than in group B (88.9% versus 97.7%; p = 0.045). No significant difference was noted in the 3-year actuarial survival rate (93.8% versus 91.6%). CONCLUSIONS: The extensive use of arterial grafts in patients with small body size was associated with excellent long-term results, with no significant increase in operative mortality or morbidity.

Body Constitution↗
PubMed1996

Hospital facilities available to patients with Kawasaki disease: results of a national survey of Kawasaki disease in Japan.

Since 1970, thirteen nationwide epidemiologic surveys of Kawasaki disease have been conducted, and questions on the current situation of hospitals and their facilities have been included in the survey form to assess the care available to patients with Kawasaki disease. To clarify the characteristics of medical care for Kawasaki disease, this paper summarizes the present condition of hospital facilities available to patients with Kawasaki disease. A questionnaire form including questions about the situation of hospital facilities was sent to all pediatric departments of hospitals with 100 or more beds throughout Japan. The proportion of hospitals in which successive observations with echocardiography (UCG) is available (UCG available hospital) was significantly increased compared with the ninth survey (1985-86), whereas that of the hospitals in which coronary angiography (CAG) is available (CAG available hospital) was significantly decreased. Almost all (96.2%) of the patients were reported from the UCG available hospitals. The proportion of patients reported from hospitals with a set policy for intravenous gamma globulin (IVGG) therapy was 74.5%. The proportion of UCG available and CAG available hospitals and that of hospitals with a set policy for IVGG therapy correlated with the increase in the number of patients. In conclusion, hospital facilities available to patients with Kawasaki disease in Japan have satisfactory capability for diagnosis and management of Kawasaki disease.

Child↗
PubMed1996

Simple evaluation method of biocompatibility of artificial oxygenator hollow fiber.

We made miniature modules filled with artificial oxygenator hollow fibers and conducted a simple experiment to study the effect of different membrane structures on the blood. Three types of modules were made: one filled with polyolefin, one filled with polypropylene, and a blank module. The 3 modules were connected through 3 fine tubings to one needle so that the same blood that passed through the 3 modules could be analyzed simultaneously. Nonheparinized blood was continuously withdrawn from 6 healthy volunteers using a small pump and passed through the circuit by a single pass (10 ml/min, for 10 min). Platelet count, thrombin-antithrombin complex, and complement-3 were measured in the blood collected at 10 min from the outlet of each module. The results showed significantly better biocompatibility of polyolefin than polypropylene, which is attributable to the dense layer of the blood contact surface of polyolefin fibers. This method is useful in assessing biocompatibility of various hollow fibers in a simple and safe manner.

Analysis of Variance↗
PubMed1996

Double balloon catheter for concomitant augmentation of abdominal organ perfusion during intraaortic balloon counterpulsation.

A newly devised double balloon catheter to augment abdominal organ perfusion concomitant with original cardiac assist during intraaortic balloon counterpulsation provided satisfactory hemodynamics and urinary output around cardiac surgical procedures in 2 patients with coronary artery disease. Some optional advantages in clinical application and problems arising in the catheter design which need to be investigated are discussed.

Acetylglucosaminidase↗
PubMed1996

Update of the epidemiology of Kawasaki disease in Japan--from the results of 1993-94 nationwide survey.

OBJECTIVE: The objective of this article is to describe the epidemiologic pictures of Kawasaki disease(KD) in Japan during the 2-year period of 1993 and 1994 based on the data obtained by the thirteenth nationwide epidemiologic survey of KD which was conducted by the Japan Kawasaki Disease Research Committee. METHODS: A survey form and diagnostic criteria of KD were sent to all hospital pediatric departments (2,640) throughout Japan with 100 or more beds. The patients to be reported in this surveys were all the incident KD cases who satisfied the diagnostic criteria. RESULTS: (1) A total of 1,730 (65.5%) hospitals responded, reporting 11,458(5,389 in 1993 and 6,069 in 1994; 6,729 males and 4,729 females; male/female ratio = 1.42) with an incidence rate of 95.1 per 100,000 children of age < 5 years. (2) The monthly number of patients was higher in winter and summer, although the monthly difference was not marked. (3) Age specific incidence rates showed a uni-modal peak at one year of age. (4) The proportion of patients with family history of KD in sibling was 1%. (5) The proportion of recurrent patients was 3%. (6) The proportion of patients with cardiac sequelae in one month after disease onset was 13%. (7) Number of fatal patients reported was 9, which conforms to 0.08% of total patients.

Child↗
PubMed1996

[Surgical treatment for ischemic cardiomyopathy].

From June 1970 to Aug. 1995. We were experienced 2,235 coronary surgical patients at the Heart Institute of Japan. Among them, the ischemic cardiomyopathy (ICM) was defined as the elective, isolated CABG with the EF of less than 20%. Among the 1,640 cases of elective, isolated CABG, the cases with the EF of less than 20% were 29, 1.8% of the total. The hospital mortality was 2 cases (6.9%). The late mortality was 2 cases. The graft patency rate was 96.6%. An actuarial survival rates at 1 year, 3 years and 5 years were 93%, 93 and 87%. Operative mortality and 5-year survival rate of CABG for ICM are acceptable, and appear comparable to that achieved in similar patients after transplantation.

Adult↗
PubMed1996

[Assessment of Japanese patients receiving heart transplants overseas].

No heart transplants have been performed in Japan due to various obstacles since the only operation performed in 1968. Since 1981, a number of patients requiring heart transplants have been accepted by foreign transplantation centers in England, the U.S.A., and Germany. This report describes an investigation of the postoperative course of these Japanese heart transplant patients and discusses the problems regarding transplantation in Japan. Of the 21 transplant patients, the diagnosis was dilated cardiomyopathy in 17, restrictive cardiomyopathy in 1, hypertrophic cardiomyopathy in 2, and congenital muscle dystrophy in 1. All patients survived surgery but three died in the long-term period. The causes of death were acute rejection (after 3 months), chronic rejection (after 50 months) and infection (after 30 months). The actuarial survival curve of these patients was 95.0% for one-year survival and 86.4% for three-year survival. The postoperative functional class was NYHA classification I in all patients (100%). Ninety-three percent of patients returned to work. Immunosuppressive therapies included triple drug therapy in 14 patients (66.7%), double drug therapy in 4 (19.0%), ciclosporin alone in 2 (9.5%) and FK506 in 2 (5.0%). The incidence of acute rejection was 1.56 episodes per patient per year within 3 months and 2.9 episodes per patient per year within 1 year. The postoperative courses of Japanese patients who underwent heart transplantation at foreign transplantation centers were satisfactory. These results will encourage heart transplantation in Japan.

Adolescent↗
PubMed1996

[Evaluation of blood absorption, hemostatic ability and purity of a polyepoxy compound cross-linked cotton type collagen hemostat].

A polyepoxy compound cross-linked cotton type collagen hemostat (CCH) made of highly purified atelocollagen in a fine filament shape was developed. To evaluate blood absorption, hemostatic ability and purity of the CCH, Avitene and Oxycel were used for comparison. Blood absorption speed of the CCH was faster than Avitene and Oxycel. The handling characteristics of the CCH were much better than those of Avitene and Oxycel. Hemostatic ability was better in the CCH compared to Avitene in a canine study. The purity of the CCH was better than in Avitene which contained albumin and other proteins. Those results suggest that the developed hemostat with excellent blood absorption, handling characteristics, hemostatic ability and purity, could be useful in clinicals.

Absorption↗
PubMed1996

Effect of HTK solution for myocardial preservation.

The aim of this study was to investigate the efficacy of HTK solution for cardioplegia in the continuous 120-minute cross-clamping method in comparison with the conventional GIK method. In an experimental model, the efficacy of ketoglutarate and tryptophan in recovering cardiac function after 6 hours' preservation was evaluated. In Group A, in which ketoglutarate was excluded from the HTK solution, percent developed pressure was significantly decreased (p<0.01) and the released enzyme (CK-MB) was significantly increased, but coronary flow was not significantly changed. In Group B, in which tryptophan was excluded from the HTK solution, a significant decrease in percent developed pressure and coronary flow was seen (p<0.01). This indicated that ketoglutarate and tryptophan were effective in protecting the myocardium during the ischemia. In the clinical study, 54 open heart operations were performed with cardioplegic solution, using either HTK solution or GIK solution. In the HTK Group, the heart was exposed to 120 minutes' of ischemia after the infusion of HTK solution (3L). In the GIK group, intermittent GIK perfusion was performed every 30 minutes in association with continuous cold blood perfusion. Percent fraction shortening and cardiac index were not significantly different. However, CK-MB and HBDH were increased in the GIK group, postoperatively. Histological findings showed deterioration of the mitochondria and myocytes during ischemia in the GIK group. These data suggest that the effect of the cardioplegias in heart preservation was satisfactory in both groups, although the interval of intermittent perfusion was prolonged to 120 minutes in the HTK solution.

Animals↗
PubMed1996

[Hemodynamic plus series of St. Jude medical valve prosthesis in aortic position: early clinical outcome and reconsideration of its application].

St. Jude Medical Hemodynamic plus bileaflet valve prosthesis (HP) was employed in 7 cases undergoing aortic valve replacement since December 1993. Echocardiographic evaluation of left ventricular dimension and transvalvular pressure gradient was performed in 5 cases with 19 HP before and after operation. Each data was compared with those of 21 cases having undergone aortic valve replacement with 19 mm Standard model (19 SD). There was no significant postoperative change in left ventricular end-diastolic dimension (50 +/- 4 mm to 44 +/- 8 mm; p = NS) and left ventricular end-systolic dimension (34 +/- 4 mm to 34 +/- 9 mm; p = NS) in 19 HP cases. However, left ventricular end-diastolic dimension (51 +/- 11 mm to 41 +/- 8 mm; p < 0.05) and left ventricular end-systolic dimension (35 +/- 12 mm to 28 +/- 9 mm; p < 0.05) decreased in 19 SD cases. Transvalvular systolic peak pressure gradient was reduced significantly in both groups (19 HP: 94 +/- 38 mmHg to 43 +/- 19 mmHg; p < 0.05, 19 SD: 73 +/- 49 mmHg to 33 +/- 14 mmHg; p < 0.05). Poor reduction of left ventricular volume and high residual systolic pressure gradient in patients with 19 HP might be due to relatively high incidence of stenotic lesion in original aortic valve disease. In some cases with these critical aortic stenosis, radical annular enlargement procedure would provide more fundamental release of left ventricular outflow tract stenosis rather than one size increase of effective orifice area by employing HPs. Structural examination demonstrated that 19 HP had the same outer diameter of sewing flange with identical orifice ring as 21 SD (24 mm) did, and 17 HP had that of 19 SD (22 mm). Therefore, precise attention is needed for application of SJM-19 HP in patients with small aortic annuli.

Adolescent↗
PubMed1996

[Long-term results and special issues of operation for infective endocarditis].

Between 1977 and June 1996, 183 patients underwent operation for infective endocarditis (IE) at our institution. Long-term mortality and morbidity were analyzed according to the STS/AATS guidelines (1988). Operative mortality including hospital deaths was 4.9% in all patients. Actuarial survival (including all deaths) at 10 postoperative years was 79.6% after AVR (n = 91), 87.9% after MVR (n = 40) and 90.0% after DVR (n = 46). There was no significant difference among 3 groups. Reoperation free and freedom from all valve-related mortality and morbidity at 10 years were 94.0% and 70.4% after AVR, 90.9% and 83.7% after MVR and 93.4% and 79.7% after DVR, respectively. And the differences among 3 groups were not significant in both freedom proportions. Overall results in this series of patients were acceptable. However, several patients with active IE and extensive perivalvular abscess were not saved even if translocation method and/or other advanced surgical procedures were applied. Introduction of aortic valve homografts might be a key factor for successful treatment for patients with extensive IE lesion.

Adolescent↗
PubMed1996

[A case of coronary artery embolism after double valve replacement].

A 69-year-old woman with combined valvular heart disease (mitral regurgitation and aortic regurgitation), ascending aortic aneurysm, and atrial fibrillation underwent double valve replacement (DVR) and, ascending aortic wall plication. The postoperative thrombo-test level was around 20%. The ST elevation on ECG (II, III, aVFm, V4 approximately V6) with chest pain were recognized on the 13 th postoperative day. She was diagnosed as having acute myocardial infarction, and percutaneous transluminal coronary recanalization was performed immediately. The coronary angiogram showed occlusion at the left anterior descending branch (#8). This lesion could be recanalized by 6,000 U plasminogen pro activator (pro-UK) administration. The cineangiogram on the 35th postoperative day, revealed complete recanalization of this occlusion. Several cases of acute myocardial infarction associated with valvular heart diseases has been reported previously in Japan. However, there has been no report, except for this case, demonstrating occlusion in the coronary artery after prosthetic replacement and successful PTCR. So, this case is the first report on that point.

Aged↗
PubMed1996

High-resolution fluorescent particle-tracking flow visualization within an intraventricular axial flow left ventricular assist device.

Flow visualization is typically applied in blood pump development to both confirm the design expectations and identify regions that may be predisposed to blood element deposition and trauma. Rotary pumps, in particular, place high demands on the technique chosen to visualize the flow given the limited visual accessibility of the flow path and the high impeller speeds. Fluorescent image-tracking velocimetry currently is used at the University of Pittsburgh Medical Center to visualize flow accurately inside of these pumps both qualitatively and quantitatively. Flow patterns under steady conditions within an intraventricular axial flow, left ventricular assist pump (prototype No. 7, SUN Medical Technology Research Corporation, Nagano, Japan) were investigated using this technique. The flow fields at the impeller-stator interface and at the pump outlet were given specific attention. This allowed the assessment of the fluid dynamics throughout the hydrodynamic design limits of the pump.

Biomechanical Phenomena↗
PubMed1996

Clinical application of a newly developed autoflow control system for the Terumo centrifugal pump: from external control to built-in direct control.

We have developed an autoflow control system for the Terumo Capiox centrifugal pump, the SP-101. First, we made an external control system regulated by a personal computer through a serial communications line. Although an in vivo experiment using a goat showed excellent performance in regulating the flow, a communication error that caused an abrupt and instantaneous flow fluctuation was noted occasionally. Therefore, we incorporated a check-sum function to solve this problem. After this improvement, 5 patients safely underwent cardiopulmonary bypass using a pump having this autoflow control. As the next step for more practical usage, we developed a built-in autoflow control system in which the control device is entirely incorporated into the console without a communications line. This system demonstrated better response and reliability than the external control system and was applied successfully in 3 patients. In conclusion, this autoflow mode will expand the usage of centrifugal pumps through improved handling.

Algorithms↗
PubMed1996

Basic performance of a miniature intraventricular axial pump.

A miniature intraventricular axial pump for left ventricular (LV) support is under development. This pump was designed for placement in the LV cavity by insertion through the LV apex with the outlet located at the ascending aorta via the aortic valve. The basic hydrodynamic characteristics represented as a relationship between pump head (H) and flow (Q) showed a negative linear relationship under a constant head. This characteristic was generally the same as that obtained by other axial rotation pumps. However, the actual H-Q relationship was represented as anticlockwise "loops" caused by the contraction of the natural LV. The comparative in vitro data on these H-Q loops showed that the shape of the loops was changed drastically by the connecting condition between the pump and natural cardiovascular system.

Animals↗
PubMed1996

A new supportive method of aortic aneurysm surgery: centrifugal left heart bypass combined with an oxygenator and a heat exchanger.

A new supportive method of centrifugal left heart bypass with oxygenation was performed in 25 patients and compared with standard left heart bypass in 45 patients. Femoro-femoral bypass was selected in another 6 patients because of the presence of a left atrial adhesion. Intraoperative complications related to standard left heart bypass, hypoxia, hypothermia, and ventricular fibrillation, were eliminated by using this method. This supportive method maintained good hemodynamics and improved the surgical result of extended thoracoabdominal aortic replacement. Hospital deaths decreased from 6.7% to 3.2%.

Adult↗