Biomedical subjects

M Shiono

Publications and source records attributed to M Shiono.

At least 55 records · Page 3Linked to original sources

PubMed1998

Left atrial myxoma with an atrial septal defect: a case report and review of the literature.

We report a case of a 49 year-old Japanese woman with a left atrial myxoma complicated by an atrial septal defect diagnosed intraoperatively, which was classified as in secundum defect and was 28x110 mm in diameter. The tumor, which was attached by a pedicle to the posterior wall of the left atrium near the posterior commissure of the mitral valve, was removed together with a small portion of the left atrial wall. The postoperative course was uneventful. The pathologic findings were consistent with the diagnosis of myxoma. Since the defect was functionally canceled by the myxoma, the diagnosis of an atrial septal defect was not confirmed preoperatively even by color Doppler echocardiography and cardiac catheterization. Tumor embolization is one of the critical complications of myxoma. Fortunately, she didn't suffer from either systemic or pulmonary emboli. During surgery of myxoma with atrial septal defect, careful manipulation is needed, especially at caval cannulation so as not to damage the tumor directly. In the cases with atrial septal defect or patent foramen ovale, myxomas are generally situated on the interatrial septum. However, in this case the tumor was located on the posterior wall of the left atrium.

Cardiac Catheterization↗

PubMed1998

Macroscopic aspects of cloth-covered Starr-Edwards prostheses at reoperation: what the precursory valve teaches us.

BACKGROUND AND AIMS OF THE STUDY: Cloth-covered Starr-Edwards ball valves were the first choice in prosthetic substitution at the authors' institution between June 1968 and March 1977. This study investigated, retrospectively, macroscopic aspects of the prostheses at reoperation. METHODS: Among 59 survivors who underwent isolated aortic or mitral valve replacement, 12 required reoperation for valve dysfunction (five aortic valve replacements, seven mitral valve replacements). Reoperation was necessitated by valvular endocarditis, paravalvular leak, hemolysis, thromboembolism, orifice stenosis attributable to pannus, and inappropriate sizing related to growth and thrombus. The mean time to reoperation was 11.7 +/- 6.2 years after initial surgery (range: 2 years 4 months to 21 years 8 months). RESULTS: Marked cloth wear was observed in all aortic prostheses, but only slight wear in mitral valves. Pannus formation was observed around the orifice in both aortic and mitral prostheses, but strut cloth was not extensively covered by autologous tissue. In mitral valves, strut cloth was only slightly worn and less loose than that of the aortic valve. These changes notably affected prosthetic valve function, the most significant problem in mitral prostheses being thrombus (four of seven valves). CONCLUSIONS: Pannus formation and thrombus caused by the reaction of the patient's tissues remain major problems in the use of artificial valves, and require further work for their improvement.

Adolescent↗

PubMed1998

Post-operative effects of olprinone after coronary artery bypass grafting.

The aim of this study was to test the effects of olprinone after coronary artery bypass grafting (CABG). In order to prevent hypotension caused by olprinone, low doses of catecolamines were used concomitantly. Total 22 elective CABG cases were evaluated. In all cases, moderate hypothermia and cardioplegic cardiac arrest were performed. In 10 cases, continuous intravenous 0.1 microg/kg/min of olprinone, 3 microg/kg/min of dobutamine (DOB) and dopamine (DOA) as the initial doses, were used concomitantly (Group I). As a control, the same initial doses of catecolamine (DOB and DOA) of Group I were administered in another 12 patients (Group II). When the pump flow of cardiopulmonary bypass (CPB) was decreased to half, these drugs were administered in both groups. Hemodynamics were recorded before CPB, just after the operation and 3, 6, 12, 24, 48, and 72 hours after the operation. Three hours after the operation, both mean aortic pressure (AoP) and pulmonary artery pressures (PAP) of Group I demonstrated significantly lower values than those of Group II. Cardiac index (CI) of Group I showed significantly higher values than that of Group II until 6 hours after surgery. The systemic vascular resistance index (SVRI) of Group I indicated a significantly lower value than that of Group II until 24 hours after the operation. Pulmonary capillary wedge pressure (PCWP) of Group I demonstrated a significantly lower value than that of Group II. There were no significant differences in urine output, oxygen delivery (DO2) and oxygen consumption (VO2) between both groups. Olprinone increased CI and decreased SVRI, and it showed easy weaning from CPB, demonstrating excellent hemodynamics after CABG. These results suggested that this new phosphodiesterase inhibitor may be effective for not only weaning from CPB but also post-cardiotomy cardiogenic shock.

Aged↗

PubMed1998

Congenital coronary artery fistula treated surgically in the right atrium and the atrial septum.

Various surgical techniques have been employed according to the type of the coronary fistula. In this case, preoperative examinations by aortography and MRI revealed a coronary artery fistula which originated from a site just proximal of the RCA, ran through the interatrial septum and drained into the posterior wall of right atrium. The ratio of pulmonary to systemic blood flow (Qp/Qs) was 1. 95. During surgery, we were not able to ligate or divide the fistula on the cardiac surface because the fistulous vessel originated from the posterior aspect of the proximal RCA. After establishing a cardiopulmonary bypass, the opening of the fistula in the right atrium was closed with an autologous pericardium patch, the surface of the interatrial septum was incised and the fistula was identified. The conduit was then divided and closed in the atrial septum. The postoperative course was uneventful. This approach is able to interrupt the fistula safely without interfering with normal coronary flow. Closure of the outlet and division of the fistula itself is a recommendable method to insure interruption of fistulous communication.

Adult↗

PubMed1997

A newly developed silicone-coated membrane oxygenator for long-term cardiopulmonary bypass and cardiac support.

The surface of polypropylene hollow fiber was successfully coated with a very thin (0.2 micron) silicone layer. Experimental studies were performed in long-term (6 h) normothermic cardiopulmonary bypass (CPB) using 10 goats. A conventional membrane oxygenator (Mera Excelung HPO-15H, MERA, Tokyo, Japan) was used for 5 goats as a control (Group C) and a new silicone-coated membrane oxygenator, which is of the same construction as that of the one used for Group C, for 5 (Group S). The O2 transfer and CO2 removal functions showed the same ranges. In the other parameters, there were no differences between the 2 groups. As for hemolysis, however, the plasma free hemoglobin of Group S was lower than that of Group C. Currently, 3 chronic percutaneous cardiopulmonary support (PCPS) experimental models have been conducted, and there has been no evidence of thromboembolism or deterioration of the oxygenator. In conclusion, this new oxygenator is suitable not only for CPB, but also for long-term cardiac support.

Animals↗

PubMed1997

Renal circulation and cellular metabolism during left ventricular assisted circulation: comparison study of pulsatile and nonpulsatile assists.

We examined left ventricular assist during 6 h for an acute myocardial infarction model in pigs. The outflow cannula was placed in the ascending aorta and an inflow cannula in the left atrium. A pump (Pulsatile group: Zeon Medical and Nonpulsatile group: Nikkiso HPM-15) was connected to each cannula. Items measured were the regional blood flow of the cortex and the medulla in the kidney, renal arterial flow, arterial blood ketone body ratio (AKBR), lactate/pyruvic acid, BUN, creatinine and beta 2-microglobulin. After experimental study, the kidneys were removed, and a pathological study was performed. In the pulsatile assisted group, renal cortical blood flow increased but medulla blood flow decreased. On the other hand, in the nonpulsatile assisted group, both regional blood flows decreased. That means that in the pulsatile assisted group intrarenal redistribution improved, rather than in the nonpulsatile assisted group. The results of our study indicated that pulsatile assist produced superior circulation in the kidney, and the microcirculation on the cell level was superior as well in early treatment of acute left heart failure.

Animals↗

PubMed1997

[Urgent replacement of aortic arch and descending aorta following replacement of ascending aorta for Stanford a aortic dissection--a case report].

A 37-year-old male who was on chronic dialysis regimen for IgA nephropathy developed acute Stanford A type aortic dissection. Replacement of the ascending aorta was performed with the aid of extracorporeal circulation, selective cerebral perfusion, and open distal anastomosis technique. The site of the intimal tear in the ascending aorta was resected and the gelatin-resorcin-formaldehyde (GRF) glue was applied to both stumps. The outside of dissecting aortic wall was reinforced with Teflon-felt strips. Two months after the operation, the patient required an urgent operation due to threatening spindle evolution of a persisting dissection in the descending aorta. Replacement of the total arch and the descending aorta was carried out via the median sternotomy with the left anterior thoracotomy, and a subclavian incision. Continuous veno-venous hemofiltration was initiated immediately after both operations and the water balance was maintained well. The patient was discharged 1 month postoperatively. It was suggested that the inside of the dissected aortic wall should be also reinforced even when the GRF glue was used in patients who have a fragile intimal flap and a wide tear.

Acute Disease↗

PubMed1997

[Three-dimensional transesophageal echocardiographic assessment for prosthetic valves].

We evaluated three-dimensional transesophageal echocardiographic assessment of the implanted mechanical valves by rotational scanning method. Patients were 7 mitral valve replacement and one aortic valve replacement, 2 mitral and aortic valve replacement. In 2 cases of 7 mitral valve replacement, the prosthetic valve regurgitation was evaluated using by color Doppler echocardiography. In this study, multiplane transesophageal probe was used. It rotated at 2-degree intervals from 0 to 180 degrees and the three-dimensional reconstruction was performed by echo scan workstation system (TOMTEC Inc, Munich, Germany). In mitral valve replacement cases, the valve motion of bileaflet valve (St. Jude Medical valve and ATS valve) were showed very clearly. The struts was easily recognized in the St. Jude Medical valve (SJM valve) cases. In one of SJM valve cases, the pannus formation was revealed, but it did not disturb valve motion. The prosthetic valve regurgitation can be seen accurately. However, aortic valve and ball valve cases cannot be reconstructed because of artifact from prosthetic valve and ultrasonic direction. The prosthetic valve regurgitation, pannus formation which was difficult to be showed in two-dimensional echocardiography and relationship between annulus and sewing cuff can be evaluated by this three-dimensional echocardiography. In this study, this system has some problems, for example real-time evaluation is impossible, aortic valve and ball valve cases cannot be reconstructed. However, we think that this new technology is suitable for evaluating valve thrombus, valve dysfunction and paravalvular leakage. In conclusion, the three-dimensional echo-cardiography demonstrated, reliable and accurate examination, and it can evaluate various complications of prosthetic valve.

Adult↗

PubMed1996

Comparison studies of major organ microcirculations under pulsatile- and nonpulsatile-assisted circulations.

In these comparison studies, we examined changes in major organ microcirculations during circulatory support using pulsatile and nonpulsatile pumps. Acute myocardial infarction was created by left anterior descending (LAD) branch ligation. After the animals in these studies fell into cardiogenic shock, they were supported by mechanical assist devices: a pulsatile ventricular assist device (VAD) in 4 pigs, a nonpulsatile VAD in 4 pigs, and an intraaortic balloon pumping (IABP) plus nonpulsatile VAD in 4 pigs. Each group was supported for 3 h with an identical mean aortic pressure being maintained. As for parameters, the stomach mucosa, liver regional blood flow, stomach mucosal pH, and arterial blood keton body ratio (AKBR) were measured. Both regional blood flow and AKBR increased in the pulsatile group as compared with the nonpulsatile group. There were no differences in the stomach mucosal pH among the 3 groups. These results suggest that pulsatile assist rather than the nonpulsatile assist plays a significant role in the recovery of deteriorated splanchnic organs due to cardiogenic shock.

Animals↗

PubMed1996

Suppression of in vitro cellular immune response by nitrogen-containing terpene alcohol derivatives.

A series of nitrogen-containing terpene alcohol derivatives were tested for their immunosuppressive effects in vitro, and KYKC-407 (erythro-1-(1-imidazolyl)-3,7,11-trimethyl-dodecane-2(S),3(R)-diol) was found to be the most effective in suppressing the induction of cytotoxic T cell (CTL) activity. CTL induction in the coculture of C3H spleen cells with mitomycin C-treated BALB/c spleen cells was suppressed by more than 90% when 4 microM KYKC-407 was added to the culture. Under these conditions, lymphocyte proliferation was also suppressed to a similar extent by this compound. Flow cytometric analysis revealed that KYKC-407 strongly inhibited the proliferation of CD8+ T cell subset, but showed less suppressive effects on CD4+ T cells. In contrast to cyclosporin A, KYKC-407 at 1-4 microM did not inhibit the proliferative response to concanavalin A. Further, KYKC-407 suppressed CTL induction even in the presence of exogenous IL-2, thus suggesting that the compound does not exert its effects through inhibiting IL-2 production.

Animals↗

PubMed1996

[A case report of a left atrial ball thrombus at 16 years after mitral valve replacement].

A free floating ball thrombus in left atrium is very rare, only 2 cases that develop ball thrombus after mitral valve replacement (MVR) have been reported. This case was a 55-year-old female who underwent MVR and tricuspid annuloplasty (TAP) in 1978. After 16 years, she developed replaced mitral valve stenosis due to pannus formation and tricuspid regurgitation (TR), with a free floating ball thrombus in the giant left atrium. A ball thrombus was taken out, and Re-MVR and tricuspid valve replacement (TVR) was carried out. Post operative course was uneventful. Because a free floating ball thrombus easily causes "Hole-in-one" sudden death, early surgical treatment must be considered.

Female↗

PubMed1996

Coronary microcirculation during left heart bypass with a centrifugal pump.

To estimate coronary microcirculation during left heart bypass (LHB), we performed an experimental comparison study of LHB and intraaortic balloon pumping (IABP). LHB was performed with a BioMedicus BP-80 pump supporting half of the flow of cardiac output whereas the IABP was pumped in a 1:1 mode for cardiogenic shock in a swine model. Coronary circulations were analyzed by electromagnetic flowmeter, pulsed Doppler velocimeter, and laser Doppler flowmeter. Left ventricular end-diastolic pressure (LVEDP) was reduced significantly by LHB. Although there was no significant difference in epicardial flow between the LHB and IABP groups, endo cardial flow was increased significantly by LHB. In the LHB group, the systolic reverse wave of the coronary velocity called a myocardial invalid circulation was reduced remarkably. There was a significant inverse correlation between endocardial flow and LVEDP. These results suggested that LHB was more effective for myocardial microcirculation than was IABP.

Animals↗

PubMed1996

Effect of pulsatile and nonpulsatile assist on heart and kidney microcirculation with cardiogenic shock.

To estimate microcirculation of the heart and kidney in pulsatile and nonpulsatile-assisted circulation, a comparison study was done using a swine model. Acute myocardial infarction was made by ligation of the left coronary artery branches. After cardiogenic shock, animals were divided into 3 groups as follows: Group C (n = 6), no assist provided; Group NP (n = 6), assisted by a nonpulsatile pump (Bio-Medicus BP-80); Group P (n = 6), supported by a pulsatile pump (Nippon Zeon). left coronary artery flow, endocardial and epicardial regional flows, and renal cortex and medulla tissue blood flows were measured. Left coronary artery flow and endocardial and epicardial tissue blood flows decreased in cardiogenic shock, and they recovered to the control level soon after support in both Group N and Group P. Renal medulla and cortex tissue blood flows decreased in cardiogenic shock, and these flows did not recover in either Group N or P. However, cortex blood flow in Group P did improve, but it did not improve in Group N. These results suggested that pulsatile assist was more effective than nonpulsatile assist for microcirculation after cardiogenic shock to avoid deterioration of major organ functions.

Animals↗

PubMed1996

Experiences of postcardiotomy assist: pneumatic ventricular assist device or venoarterial bypass with percutaneous cardiopulmonary support.

From October 1982 to the present, 16 patients have been supported by a pneumatic ventricular assist device (VAD). Since April 1990, we have introduced a venoarterial bypass (VAB) with percutaneous cardiopulmonary support (PCPS) system. This PCPS system was used in 12 patients. The long-term survival rate of PCPS cases (41%) was much better than that of VAD cases (19%). The main cause of death in VAD cases was multiple organ failure (MOF). Although VAB was initiated more recently than VAD, the duration on support was longer in the VAD group than in the VAB group. Because of the longer support duration and the presence of many patients with MOF, coagulopathy deteriorated more readily in the VAD group than in the VAB group. In the case of postcardiotomy cardiopulmonary bypass weaning or low-output syndrome (LOS), the VAB with PCPS system should be applied first under intraaortic balloon pumping assist because of its simplicity and low cost. Thereafter, VAD should be applied in cases refractory to VAB support.

Adult↗

PubMed1996

Preliminary experimental study about the feasibility of combining pulsatile cardiopulmonary support system and a membrane oxygenator.

A cardiopulmonary support (CPS) device that incorporated a pneumatic ventricular assist device (VAD) and a membrane oxygenator was developed for the support of patients with profound heart and/or respiratory failure. This device has an advantage of being both a pulsatile assist device and membrane oxygenator. A "triple flow" regulator was included in this system to control the blood flow through the oxygenator. The purpose of this study was to clarify the efficacy of this system in supporting an animal model with combined cardiac and respiratory failure. In vitro tests showed 3.7 L/min of pump flow under 1.6 L/min of oxygen supply to the oxygenator even though there was a 50% clamp of a "triple flow" regulator with sufficient pulsatility. In 14 acute canine experiments, cardiogenic shock and acute respiratory failure were introduced by coronary ligation and mechanical hypoventilation simultaneously. The pump flow was maintaned at 1.95-0.6 L/min (average 1.2 L/min) and the driving pressure of the pump was controlled between 200 and 300 mmHg positive pressure and -20 to -50 mmHg negative pressure. The driving rate was fixed at 100 bpm and systolic/diastolic ratio was controlled between 35-50%. The canines were divided into control group (n = 4) and pumped group (drained from the right atrium n = 7, drained from the left atrium n = 3). By using CPS system, flow and aortic pressure recovered to the initial baseline level. Without this support, the canine model could not maintain systemic circulation. In the group drained from right atrium, central venous pressure decreased with the device from 13.9 +/- 2.4 to 5.6 +/- 1.4 cm H2O (p < 0.01), returned to the initial level without this device (p < 0.01). In the group drained from left atrium, pulmonary capillary wedge pressure decreased from 37.9 +/- 4.6 to 20.8 +/- 5.7 mmHG (p < 0.01), and returned to the initial level without the device, arterial oxygen tension levels increased tension levels increased (p < 0.01), and also arterial oxygen saturation levels recovered (p < 0.01). The results suggest that the current model of the pulsatile CPS has a potential to support the animal model with combined cardiac and respiratory failure.

Animals↗

PubMed1994

[A case of congenital solitary tricuspid regurgitation treated with tricuspid valvular replacement].

A case of congenital solitary tricuspid regurgitation was reported. The patient was a 43-year-old male. The echocardiogram and ventriculography showed severe tricuspid regurgitation. The tricuspid valve was hypoplastic in each leaflet and chordae without torn chordae and papillary muscles. A tricuspid valve replacement was performed using St. Jude Medical 33 mm valve. As of June 1993 nine patients with this disease undergoing surgery were reported around the world.

Adult↗

PubMed1994

[A case of mitral stenosis with a new open pivot bileaflet valve].

The ATS Medical Open Pivot Bileaflet Valve was developed by Villafana who also developed St. Jude Medical valve and put to the first clinical use by Sadeghi on May 4, 1992. Since then, its clinical uses have been made in cases more than 1,000 in the world, centering on Europe, and its usefulness has been reported elsewhere from the aspected of its durability, anti-thrombogenic property, hemolysis, less noise and surgical operability. ATS valve was developed with 9 characteristics as (1) open pivot; (2) removed Struts; (3) wide area orifice; (4) improved stillness; (5) improved durability; (6) small loss of energy; (7) rotating orifice; (8) x-ray impermeability of orifice; (9) and easily sutured orifice. A report is made here on our experience of a clinical case of mitral stenosis by ATS valve (the first case in Japan) on September 28, 1993.

Female↗

PubMed1993

A seal-less centrifugal pump (Baylor Gyro Pump) for application to long-term circulatory support.

We are developing a new centrifugal pump, the Baylor Gyro Centrifugal Pump (Gyro Pump), which can function for more than 2 weeks. The concept of the Gyro Pump is that a one-piece rotor-impeller with embedded permanent magnets, driven directly by a brushless direct current motor stator placed outside, rotates like a "gyroscope," and the rotor-impeller is supported by one pivot bearing at the bottom in accordance with the gyroscopic principle. This concept enables us to eliminate a driving shaft and a seal between the driving shaft and the blood chamber, which results in extending the life of the centrifugal pump. The blood passes through the space between the motor stator and the rotor to the impeller portion. In this preliminary phase, two pivot bearings were applied to support the rotor-impeller at the top and the bottom inside the blood chamber. Both pivot bearings showed less blood trauma and less thrombogenicity in in vitro and in vivo studies. The Gyro Pump is a promising second-generation centrifugal pump for long-term circulatory support in the near future.

Animals↗