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Biomedical subjects

S Fukunaga

Publications and source records attributed to S Fukunaga.

At least 55 records · Page 3Linked to original sources

Constrictive pericarditis following hemopericardium due to ascending aortic dissection: A case report.

A 79-year-old woman, who had had no history of trauma, tuberculosis, or collagen diseases, was referred for examination of general fatigue and shortness of breath on exertion. Physical examination revealed engorged neck veins, hepatomegaly, and ascites with abdominal distention. On chest x-ray the cardiac shadow was slightly enlarged and bilateral pleural effusion was present. An electrocardiogram showed low voltage of the QRS complex. Computed tomographic scans revealed two lumens in the remarkably dilated ascending aorta and the severely thickened pericardium. Cardiac catheterization showed elevated right atrial pressure and elevated right and left ventricular end-diastolic pressures, in addition to a pressure record of early diastolic dip and end-systolic plateau in the right ventricle. Aortography demonstrated aortic dissection localized to the ascending aorta. On the basis of these findings, the diagnosis of chronic ascending aortic dissection complicated with constrictive pericarditis was made. After subtotal pericardiectomy, graft replacement of the ascending aorta and proximal aortic arch was performed with successful results. Her postoperative recovery was uneventful. Histological studies of the pericardium showed fibrosis and marked infiltration of the inflammatory cells. No findings of specific pericarditis such as tuberculosis or collagen diseases were detected.

Aged↗

Simultaneous repair of cardiovascular disorders and pectus deformity in a patient with Sprintzen-Goldberg syndrome: A case report.

We report a 12-year-old girl with Sprintzen-Goldberg syndrome (SGS) who was complicated with annuloaortic ectasia with aortic regurgitation, mitral valve prolapse with mitral regurgitation, and a severe pectus excavatum. In this patient, aortic root replacement, mitral valve replacement, and sternal elevation were simultaneously performed, and a version of Ravitch's procedure that was technically modified to support the sternum was used for sternal elevation. This modified sternal elevation technique gave excellent operative exposure, and maintained chest wall stability after the operation.

Aortic Aneurysm↗

An aortic balloon catheter incorporating a conduit for percutaneous cardiopulmonary support.

Circulatory support using both intraaortic balloon pumping (IABP) and percutaneous cardiopulmonary support (PCPS) can improve general hemodynamics; however, sometimes brain damage occurs caused by hypoperfusion. Such cerebral hypoperfusion is likely to be caused by PCPS when applying the conventional femoral cannulation. We have developed a new IABP catheter which incorporates a conduit for PCPS with an outlet at the catheter tip, the goal of which is the improvement of cerebral perfusion. The hemodynamic characteristics of this new IABP catheter were compared with those of the conventional combination of IABP and PCPS. Studies were performed by mock test using a pulsatile artificial heart. A polyvinyl chloride tube acted as the aorta with 2 branches at the proximal and distal portions representing the upper and lower portions of the body. The IABP balloon was positioned between the 2 branches, and changes in flow at the 2 branches were examined at varying PCPS flow rates. Flow in the proximal branch using the new device was greater than it was using the conventional PCPS device. We conclude that cerebral perfusion could be improved with the use of this new special IABP catheter.

Angioplasty, Balloon, Coronary↗

Study of left ventricular bypass using Wankel type semipulsatile blood pump.

The influence of the Wankel type semipulsatile left ventricular assistance on hemodynamics was investigated with a computer simulation and an animal experiment. A simulation circuit was constructed to express the circulatory system. A current source was added to create a semipulsatile blood pump. The left and right ventricles were replaced by variable compliances. Left heart failure was simulated by decreasing the amount of compliance change of the left ventricle. Under the condition of heart failure when semipulsatile assist flow increased, the mean aortic pressure (AoP), tension time index (TTI), and diastolic pressure time index (DPTI) increased, and the cardiac output, pulse pressure (PP), and pulsatility indicator (PI) decreased. In an animal experiment, a Wankel type blood pump was used in a calf. With the increase of the assist flow, AoP curves became less pulsatile, and PP and PI decreased in accordance, which was predicted by the numerical simulation.

Animals↗

Eccentric roller type total artificial heart designed for implantation.

In the process of developing a completely implantable total artificial heart system, we have made an eccentric roller type total artificial heart and evaluated it by means of a mock circulatory system and by an acute animal experiment. The actuator of the artificial heart consists of 2 cylindrical drum type rollers which squeeze 2 blood chambers. The blood chambers are made of silicone rubber and are torus in shape. There is no valve used in this artificial heart. The artificial heart appears to be a nearly circular cylinder, approximately 10 cm in length and 8 cm in diameter. In the Donovan mock test, the artificial heart worked at a roller speed of 100-125 rpm with flow rates of 2.5-3.0 L/min for the right side and 3.2-3.8 L/min for the left side, respectively. The electric power consumption was 19.0-24.7 W. Our artificial heart is characterized by an ejection of blood alternatively in the pulsatile mode without need for reversing the motor. In the ex vivo evaluation, circulation of an adult sheep was maintained with this artificial heart for 4 h.

Animals↗

Maternal thyroid function in multiple pregnancy: the variable thyrotropic activity of human chorionic gonadotropin.

The present study was undertaken to evaluate thyroid function and thyrotropic action of hCG in multiple pregnancy. We examined serum samples from 9 multiple pregnant women (3 triplets and 6 twins) and 27 singleton pregnant women as control subjects. Serum hCG levels in multiple pregnancy were higher than those in singleton pregnancy in the second and third trimesters (P < 0.01). The mean free T3 and T4 concentrations in multiple pregnancy did not differ from those in singleton pregnancy in each trimester. Serum hCG levels showed a statistically significant positive correlation with free T3 and T4 levels in singleton pregnancy (P < 0.001). However, these correlations were not observed in multiple pregnancy. Thyroid stimulation activity (TSA) determined by cAMP accumulation in FRTL-5 cells in multiple pregnancy sera was significantly higher than that in singleton pregnancy in the first trimester (P < 0.05), but did not differ in the second and third trimesters. Moreover, TSA did not show any correlation with serum hCG levels in multiple pregnancy in contrast with the results in normal pregnancy. A bioactivity/immunoreactivity ratio of hCG in multiple pregnancy was lower than in singleton pregnancy in the second and third trimesters. The discrepancy between immunoreactivity and thyrotropic activity of hCG may be caused by the variable thyrotropic potency of heterogeneous hCG molecules in multiple pregnancy.

Adult↗

Aortic valve replacement with a small mechanical valve prosthesis--a clinical and echocardiographic study of a St Jude Medical valve prosthesis.

The use of small aortic valve prostheses raises concerns about harmful effects of residual obstruction to left ventricular outflow. The present study was undertaken to examine long-term clinical and echocardiographic results in 193 patients who underwent isolated aortic valve replacement (AVR) with a St Jude Medical (SJM) valve of 25 mm or smaller. The study subjects comprised 128 male and 65 female patients with a mean age of 54.1 years. The patients were divided into 2 groups according to the size of the valve prosthesis used for AVR. Small valves (19 or 21 mm) were implanted in 49 patients (group S) and large valves (23 or 25 mm) were used in 144 patients (group L). The group S patients were mainly female, older, and had smaller body surface areas. There were no significant differences in early and late mortality in group S as compared with group L. Furthermore, there was no difference in the incidence of valve-related or cardiac, non-valve-related death, including the incidence of sudden death, between the 2 groups, and they enjoy a similar level of daily routine activity regardless of the valve size used. Left ventricular (LV) function (ejection fraction, fractional shortening, LV mass index, LV end-systolic volume index, and LV end-diastolic volume index) measured by echocardiography improved significantly and returned to normal values after AVR in both groups. Moreover, no significant differences were observed in the postoperative variables of the LV function. These results suggest that 19-mm and 21-mm SJM valves can be safely used for AVR in the majority of Japanese patients.

Aged↗

Assessment of a new silicone tri-leaflet valve seamlessly assembled with blood chamber for a low-cost ventricular assist device.

We have developed a practical, low-cost ventricular assist device (VAD) comprising a newly designed blood chamber with a silicone lenticular sac and two silicone tri-leaflet valves (STV), made en bloc. This new VAD is seamless, can be made cost-effectively and assembled with the blood chamber and valve as one body. This novel design should reduce the incident of thrombus formation because of the absence of a junction at the connecting ring and because of the use of flexible silicone materials which have both antithrombogenecity and biocompatibility. In in vitro hemodynamics testing, a batch of 3 consecutively manufactured VADs with STVs underwent hydrodynamic functional testing. These showed less regurgitation, a lower value of water hammer phenomenon, and a slightly greater pressure gradient across the valves than a mechanical valve (MV) [Björk-Shiley monostrut valve]. The flow and pulsatile efficiency were adequate and similar to that of a VAD with MVs. In in vitro durability and hemolysis tests, a VAD with STV functioned well for 54 days and showed similar hemolytic profiles to a VAD with MVs. In an in vivo acute experiment using an adult sheep, our device was problem-free providing sufficient output as a left ventricular assist device (LVAD). Although it will be necessary to decrease the pressure gradient across this STV in the future, our device showed efficient performance as a practical land cost-effective VAD for short term use.

Adult↗

Operation for type B aortic dissection using hypothermic selective cerebral perfusion.

A 56-year-old man who had a huge type B dissecting aortic aneurysm extending from the distal arch to the thoracoabdominal aorta underwent replacement of the descending thoracic and thoracoabdominal aorta under hypothermic circulatory arrest with selective cerebral perfusion. The intercostal arteries at the T-8 to T-11 level were preserved with beveled distal anastomosis, and the celiac artery and the intercostal arteries at the T-5 and T-6 levels were reconstructed. The patient recovered uneventfully and is presently doing well 1 year after the operation.

Aortic Dissection↗

Development of a direct mechanical left ventricular assist device for left ventricular failure.

We have developed a direct mechanical left ventricular assist device (DMLVAD) for severe left ventricular failure. The DMLVAD was attached to the left ventricle and compressed the heart by a pneumatic driving unit. In a mock circulation model with an extracted nonbeating heart, a cardiac output (CO) of 1.93 L/min was obtained at a driving pressure of 200 mm Hg. In a canine left ventricular failure model induced by injection of sodium hydroxide into the myocardium, the systolic arterial pressure, systolic left ventricular pressure, maximum LV dP/dt, peak flow, and CO increased by 21, 24, 58, 144, and 37%, respectively. The mean left atrial pressure also decreased by 15% when the DMLVAD was driven. These effects were most prominent when the mean left atrial pressure was over 15 mm Hg, and the driving pressure was over 100 mm Hg. Compression at late systole was more effective in obtaining greater CO. We suggest that the DMLVAD could be an optional circulatory assist device for patients with left ventricular failure awaiting heart transplantation.

Animals↗

Development of an intravascular pumping oxygenator using a new silicone membrane.

A new intravascular pumping oxygenator (IVPO) was developed for intravascular gas exchange and circulatory assistance in critically ill patients with respiratory and circulatory failure. The IVPO utilizes new silicone hollow fibers (diameter, 1 mm; membrane width, 50 microns) and consists of two driving tubes for the oxygenation and pumping of circulating blood. The performance characteristics of the IVPO were studied using an experiment ex vivo model. With a mean hemoglobin concentration of 10.5 +/- 2.3 g/dl, total oxygen transfer was 5.6 +/- 1.5 ml/min at a blood flow of 200 ml/min and 6.3 +/- 2.2 ml/min at a blood flow of 250 ml/min. Total CO2 transfer was 3.8 +/- 1.4 ml/min at a blood flow of 200 ml/min and 4.2 +/- 1.6 ml/min at a blood flow of 250 ml/min. Blood flow increased to a maximum of 250 ml/min during IVPO pumping. This preliminary experiment demonstrated that the IVPO has the capacity to function both as circulatory assist pump and as an intravascular hollow fiber oxygenator.

Animals↗

Trial manufacture of eccentric roller type total artificial heart.

Working toward a completely implantable total artificial heart, we have designed an eccentric roller type total artificial heart. The actuator of this artificial heart is a drum type eccentric roller that squeezes the blood chambers. The blood chambers are made of silicone rubber and are torus in shape. The shape of the artificial heart is an almost circular cylinder, and its length and diameter are 10 cm and 8 cm, respectively. The 2 main characteristics of this artificial heart are that it discharges blood in a pulsatile mode and that it requires no reversing of the motor. Because we have not completed the artificial heart yet, we have tested the eccentric roller mechanism on the prototype with an overflow type mock circulation with a 100 mm Hg afterload. The prototype worked at the roller speeds of 50, 100, and 150 rpm with flow rates of 1.7, 3.7, and 5.4 L/min, respectively. Next the prototype was connected to a Donovan type mock circulatory system and worked at roller speeds of 88-214 rpm with flow rates of 3.0-8.4 L/min against mean afterloads of 82-120 mm Hg.

Biocompatible Materials↗

Aortic root replacement for annuloaortic ectasia in Shprintzen-Goldberg syndrome: a case report.

Annuloaortic ectasia due to Shprintzen-Goldberg syndrome (SGS) is reported. A 10-year-old boy was admitted to our hospital for evaluation of chest pain. On admission, he was diagnosed as SGS on the basis of his various anomalies. Two-dimensional echocardiography showed a bicuspid aortic valve and marked annular dilatation, Doppler flow studies revealed severe aortic regurgitation, and retrograde aortography showed severe aortic regurgitation with annular dilatation. Successful aortic root replacement was performed; subsequent histologic examination of the ascending aorta demonstrated cystic medial necrosis. In conclusion, SGS is a generalized connective tissue dysplasia, with clinical manifestations of cardiovascular lesions similar to those in Marfan syndrome. Aortic root replacement was successfully performed; however, recurrence of aortic aneurysms outside of the ascending aorta should be carefully observed. Surgical treatment for cardiovascular disorders may be necessary to save the life of patients with SGS.

Abnormalities, Multiple↗

Cineradiographic evaluation of ATS open pivot bileaflet valves.

BACKGROUND AND AIMS OF THE STUDY: Echocardiography and cineradiography are both valuable for the evaluation of prosthetic valve function, especially of mechanical valves. Although Doppler echocardiography data are available for the recently developed ATS valve, cineradiographic evaluation of leaflet movement of the valve has not been performed. MATERIALS AND METHODS: Five patients received aortic and another five mitral valve replacement with the open pivot ATS bileaflet prosthetic valve. There were three men and seven women; mean patient age was 58.8 years. Cineradiographic and Doppler echocardiographic evaluations of the ATS valve were performed early after surgery in all 10 patients. RESULTS: There were no early deaths after surgery or after discharge from the hospital. No valve-related complications were seen, and no clinical symptoms or signs of prosthetic malfunction were observed during the follow up period. Doppler-derived values of the ATS valve were comparable with those previously reported; however, cineradiography of the valve demonstrated that the mean angle enclosed by the two open leaflets was 37.6 degrees (range: 34 degrees to 44 degrees) in the aortic position and 29.7 degrees (range: 20 degrees to 35 degrees) in the mitral position. Mean leaflet mobility was 93.0 degrees (range: 86 degrees to 96 degrees) in the aortic position and 100.0 degrees (range: 92 degrees to 110 degrees) in the mitral position. Thus, the opening of the normally functioning ATS valves in vivo was less than that observed in vitro and reported by the manufacturer. CONCLUSIONS: These results suggest that unevenly distributed blood flows with different velocities through the two side orifices and the central orifice may result in incomplete opening of the ATS leaflets, which respond with great sensitivity to localized blood flow. Our findings appear to be important to avoid the removal of a normally functioning ATS valve only because the leaflet opening appears to be 'restricted'.

Adult↗

[Combined superior-transseptal approach to left atrial myxoma].

A 60-year-old woman was referred to our hospital for treatment of an intracardiac tumor Echocardiography revealed a 47 x 30 mm tumor in the left atrium which had a short stalk attached to the atrial septum. At operation, a large left atrial myxoma was extirpated using a combine superior transseptal approach. Through this incision, exposure of the left atrial myxoma and it stalk was excellent and removal of the myxoma was easily performed with minimal minpulation. Postoperative arrhythmias related to the operative procedures were not observed. The patient recovered uneventfully. The operative technique and indications of the combined superior transseptal approach to the left atrium are discussed in this paper.

Cardiac Surgical Procedures↗

[Heart valvular disease in patients 70 years old and older].

From June 1986 to December 1996, 69 patients older than 70 years old underwent AVR (29 cases), MVR (21 cases), MVP (5 cases), DVR (10 cases), aortic root replacement (3 cases), repair of PVL (1 case) in our hospital. There are five (7.2%) operative and hospital deaths. The survival rate was 88.4% at 10 year after surgery and three (4.7%) late deaths. The factors associated with early deaths were renal dysfunction and DVR. Our surgical results suggest that open heart surgery can be performed safely even elderly patients, in spite of their precarious physiologic homeostasis. Not the chronological age but the physiological age is important determinant for surgical indication. If quality of life (QOL) can be expected to be enhanced, we recommend an aggressive surgical approach.

Age Factors↗

Obstruction of mechanical valve prostheses: clinical diagnosis and surgical or nonsurgical treatment.

Twenty patients underwent nonsurgical and/or surgical treatment for obstruction of mechanical prosthetic valves. The obstructed prosthetic valve was in the aortic position in 11 patients, in the mitral position in 5, and in the tricuspid position in 4. Twelve patients had a bileaflet valve (3 aortic, 5 mitral, 4 tricuspid), and 8 had a tilting disk valve (all aortic). The diagnosis of prosthetic valve obstruction was made by cineradiography and echocardiography. Thrombolytic therapy was instituted in a series of our 10 most recent patients (11 cases), except for one patient with acute renal failure, regardless of the position of the obstructed prosthetic valve. Successful thrombolysis was achieved in 6 cases (54.5%). Six patients required surgical treatment subsequent to either failed or incomplete thrombolysis, and one patient died of congestive heart failure 1 month after surgery. Nonfatal neurologic events occurred in 2 cases (18.2%). A total of 16 patients underwent surgical treatment. Two (12.6%) of the 16 patients died of causes unrelated to the operative procedures before discharge from the hospital. These results suggest that thrombolytic therapy appears to be an attractive nonsurgical alternative for valve thrombosis when the patient's clinical condition is not critical, and thus surgical treatment should only be performed in an emergency on seriously ill patients.

Adult↗