Biomedical subjects

M Shiono

Publications and source records attributed to M Shiono.

At least 19 recordsLinked to original sources

PubMed2003

[Reoperation for a Starr-Edwards ball valve prosthesis implanted in mitral position 31 years ago].

The patient is a 61-year-old woman who had undergone mitral valve replacement with the Starr-Edwards cloth-covered ball valve 31 years ago. She had dyspnea on effort 1 month before admission. The echocardiography revealed mitral and tricuspid regurgitation. Re-replacement of the mitral prosthetic valve with an ATS valve and tricuspid annuloplasty were successfully performed without any complication. The cloth wear of the Starr-Edwards ball valve cage was recognized and no thrombus was found at operation. To our knowledge, there has been no such a reoperative case who underwent so long postoperative period after initial implantation of the Starr-Edwards ball valve in Japan. This experience made us realize again the importance of attention to the complications related to a prosthetic valve like a cloth wear during long-term follow-up for the Starr-Edwards ball valve.

Female↗

PubMed2001

Caged and clustered structures of endothelin inhibitor BQ123, cyclo(-D-Trp-D-Asp--Pro-D-Val-Leu-)-Na+, forming five and six coordination bonds between sodium ions and peptides.

BQ123 is a cyclic pentapeptide and a potent endothelin-1 inhibitor. The crystal structure of the BQ123 sodium salt was determined as the first example of an endothelin inhibitor. Four independent molecules and many solvent molecules were found in the asymmetric unit; the total weight was about 3000 Da. The precise structure including the solvent molecules was determined using high-resolution data collected on a synchrotron source. Sodium ions formed unique structures with five and six coordination bonds and their forms were distinguished into three classes. An ion was sandwiched by two BQ123 molecules. This peptide-sodium (2:1) complex showed a cage-like structure and octahedral coordination was observed. Sodium ions also formed a cluster composed of hydrated water molecules and peptides. Two sodium ions were contained in this cluster, making five coordination bonds. Despite having the same coordination numbers, these ions were distinguishable by differences in the polyhedra. One was trigonal bipyramidal (having six planes) and the other was square pyramidal (having five planes). Both shapes were very similar to each other, although the synchrotron data clearly revealed slight geometrical differences.

Endothelin Receptor Antagonists↗

PubMed2001

Ab initio structure determination of icosahedral Zn-Mg-Ho quasicrystals by density modification method.

A novel density modification method is applied for the first time to phase reconstruction of x-ray single crystal data of quasicrystals. The structure of icosahedral Zn-Mg-Ho quasicrystals has been determined by means of this ab initio structure determination within a framework of a 6D description. The location, size, and shape of the occupation domains are deduced. The suggested Ho sites in the 3D structure are consistent with the results of magnetic diffuse scattering [T. J. Sato et al., Phys. Rev. Lett. 81, 2364 (1998)].

Journal Article↗

PubMed2001

The estimation of cardiac function from the rotary blood pump.

The rotary blood pump is implanted as a bridge to cardiac transplantation. Mechanical, histological, and biochemical improvements have been described in patients after implantation of left ventricular assist devices (LVADs). Thus, the rotary blood pump might be used as a bridge to recovery of myocardial function. However, unlike a pulsatile pump, the rotary blood pump cannot be stopped to estimate cardiac function: if the rotary blood pump stops, backflow will occur. In this study, a new method that can estimate cardiac function without pump stop was examined. Six pigs were the subjects of this acute study. The pump was implanted as an LVAD: the inlet cannula was inserted into the left ventricle, and the outlet cannula was inserted into the ascending aorta. The motor speed was regulated at a pump flow rate of 0 L/min at diastolic phase. Then, the relationship between the dp/dt of left ventricular pressure and external stroke work of actuator was examined. This method was studied at normal, hyperdynamic, and heart-failure conditions. There was a high positive correlation between the dp/dt of left ventricular pressure and external stroke work of actuator. This method is useful and simple to estimate cardiac function without pump stop.

Animals↗

PubMed2001

Effects of left ventricular assist device on cardiac function: experimental study of relationship between pump flow and left ventricular diastolic function.

The left ventricular assist device (LVAD) with centrifugal pump has two characteristics. One is a pump flow wave of the centrifugal pump, consisting of the pulsatile flow of the native heart and the nonpulsatile flow of the centrifugal pump. The other is that the centrifugal pump fills from the native heart not only in the systolic phase, but also in the diastolic phase. In the case of the apex outlet LVAD with centrifugal pump, blood flows from the left atrium through the left ventricle to the pump. Pump flow is regulated by preload, and preload is regulated by diastolic hemodynamics. The aim of this study is to analyze the relationship between pump flow and the diastolic hemodynamics of the native heart. Ten anesthetized intact pigs were studied after placement of an LVAD. Data were recorded with the LVAD off (control) and the LVAD on. The assist rate was changed to 25%, 50%, and 75%. The indexes of left ventricular (LV) diastolic function included LV myocardial relaxation (time constant of isovolumic pressure decay [Tau] and maximum negative dP/dt [LV dP/dt min]) and LV filling (peak filling rate [PFR], time to peak filling rate [tPFR], and diastolic filling time [DFT]). Stroke volume decreased significantly in 75% assist. LV end-systolic pressure decreased significantly in 50% and 75% assist. LV end-diastolic volume decreased as assist rate increased, but there were no significant changes. Stroke work decreased significantly in 50% and 75% assist. LV dP/dt min decreased significantly in 50% and 75% assist. Tau prolonged as assist rate increased, but there were no significant changes. DFT shortened significantly in 75% assist. PFR increased significantly in 75% assist. tPFR shortened significantly in 50% and 75% assist. In this study, LV relaxation delayed as an increasing of pump assist rate, but it suggested a result of reduction of cardiac work. Also, it was suggested that LVAD increases the pressure difference between the left atrium and the left ventricle in the diastolic phase. This phenomenon is due to the filling of the left ventricle. In this study it was suggested that as pump assist rate increases, it is more effective to keep cardiac function in the diastolic phase.

Animals↗

PubMed2001

Ab initio structure determinations by direct-space methods: tests of low-density elimination.

The low-density elimination method, which was developed for phase extension and refinement, has been investigated regarding its power to solve crystal structures starting from completely random phase sets. The method employs a multi-solution strategy. Low-symmetry structures are easily solvable where phase restrictions are only applied to a few reflections. Even with high-symmetry structures, a reasonable solution was obtained regarding centric reflections as general reflections. It is also shown that the structure of a small protein ribonuclease Ap1 is solvable if the positions of the five S atoms in the protein are known.

Crystallography↗

PubMed2001

Transfer of canine embryos at various developmental stages recovered by hysterectomy or surgical uterine flushing.

In dogs, embryo transfer (ET) techniques such as induciton of excessive ovulation and synchronization of estrus have not progressed well. Therefore, using embryos at various developmental stages, ET was investigated in dogs from a beagle colony in which the ovulation days were close, as estimated by the progesterone level. Embryos were, recovered 8-11 days after ovulation (4-9 days after mating) by excising the oviducts and uteri (excision method) in 16 animals and by surgical flushing of the uteri at laparotomy (surgical method) in 3 animals. In 24 dogs with -4 to +2 days of difference in the timing of ovulation between donor and recipient dogs, 1-10 embryos at the 8-cell to blastocyst stages were transferred per animal. The mean embryo recovery rate by the excision method (97.1%) was significantly higher than that by the surgical method (42.5%) (p<0.01). Twelve (57.1%) of 21 animals with -1 to +2 days difference in ovulation day became pregnant after the transfer of 8-cell to blastocyst stage embryos. Although 3 dogs with -4 to -2 days of difference of ovulation day underwent ET of morula or compacted morula, none of these dogs became pregnant. The mean ratio of the number of newborns to the number of transferred embryos was only 51.9%. The mean duration of the period between ovulation and delivery in the pregnant recipients was 65.8 days, which tended to be longer than that in natural mating. These results demonstrate that pregnancy can be induced by ET at the 8-cell to blastocyst stage in dogs with -1 to +2 days difference in ovulation day.

Animals↗

PubMed2001

Doppler echocardiographic evaluation of St. Jude Medical valves in the tricuspid position: criteria for normal and abnormal valve function.

BACKGROUND: Although this examination for mitral and aortic prosthetic valves has been frequently reported to be available for the early diagnosis of complications, there are few reports on examinations for tricuspid prosthetic valves, particularly the mechanical valve such as the St. Jude Medical (SJM) valve. Furthermore, the criteria for early diagnosis of complications are unknown. The purpose of this study is to evaluate the SJM valve in the tricuspid position by Doppler echocardiography and to analyze valve-related complications. METHODS: Between September 1978 and March 1997, 46 patients underwent tricuspid valve replacements with SJM valves; these cases were evaluated by Doppler echocardiography. We divided the cases into Normal and Complication groups. RESULTS: In the Normal group, peak pressure gradient was 4.2+/-1.5 mmHg and pressure half-time was 123.5+/-22.9 msec. In the Complication group, peak pressure gradient was 12.7+/-3.6 mmHg and pressure half-time was 271.8+/-76.4 msec. In the Complication group, the lowest peak pressure gradient case was 8.0 mmHg and the shortest pressure half-time was 160.0 msec. CONCLUSIONS: We concluded that when the peak pressure gradient is more than 8 mmHg or the pressure half-time is more than 160 msec, there is a possibility of complications. Despite the problems, the absence of any structural change after more than ten years suggests that the SJM valve can be used in the tricuspid position with careful follow-up.

Adult↗

PubMed2001

Evaluation of St. Jude Medical valve's long-term function by Doppler echocardiography.

In this study, the long-term function of St. Jude Medical valve (SJM valve) is evaluated by Doppler echocardiography. The subjects were 191 patients who underwent mitral or aortic valve replacement using SJM valve in our institute since July 1978 and had no clinical problem showing more than 50% of left ventricular ejection fraction. The patients were classified into 3 groups according to measurement period (within 5 years, 10 years and 15 years and more), and further classified by size and their results were compared. In every group by size, there was no significant difference among groups by measurement period. In the mitral valve position, peak pressure gradient and pressure half-time were not significantly different among groups by size. On the other hand, in the aortic valve position, pressure gradient in 21-mm group was significantly high among 21-mm, 25-mm, and 27-mm groups, showing a negative correlation with size. As the result, it was suggested that SJM valve kept a good function more than 15 years after operation. From these results, it was considered that the patients with small annlus of the aortic valve needed annulus-enlarging procedure or use of Hemodynamic Plus series valves to keep the size of more than 23 mm.

Adult↗

PubMed2000

Evaluation of valve sound and its effects on ATS prosthetic valves in patients' quality of life.

BACKGROUND: We interviewed patients and carried out frequency analyses to compare the closing sounds of ATS and St. Jude Medical (SJM) prosthetic valves. METHODS: Forty-five patients undergoing valve replacements using ATS valves were investigated. We interviewed patients at 1 month and 1 year after the operation, and carried out frequency analysis to investigate the prosthetic valve's closing sound. RESULTS: According to the results of the interviews, 84.4% of patients with ATS valves were not aware of the valve sounds. ATS valves scored significantly lower than SJM valves on audibility of the valve sound, disturbance during daytime, sleep disturbance, request for replacement with a soundless prosthetic valve, audibility to others, and noise index. According to the frequency analysis on the prosthetic valve's closing sound, the sound peak of the ATS valves was around 1.2 kHz, and the sound pressure of the ATS valves was significantly lower than that of the SJM valves. CONCLUSIONS: Though a further long-term observation on thromboembolism and hemolysis is needed for evaluation of prosthetic valves, the ATS valve is presently considered to impart a better quality of life.

Adult↗

PubMed2000

Low-dose continuous infusion of human atrial natriuretic peptide during and after cardiac surgery.

BACKGROUND: We evaluated the effects of human atrial natriuretic peptide (hANP) during cardiopulmonary bypass (CPB). METHODS: Forty patients undergoing coronary artery bypass grafting were investigated. A group of patients given hANP for 24 hours from the start of CPB (hANP group) was compared with a non-hANP group. Parameters examined were hemodynamics, urine volume, dosage of furosemide, respiratory index, pleural effusion, ANP, cyclic guanosine monophosphate, renin activity (renin), angiotensin-II, aldosterone, and glomerular filtration rate. RESULTS: Central venous pressure, systemic vascular resistance index, and pulmonary vascular resistance index were significantly lower in the hANP group than in the non-hANP group. The hANP group showed significantly higher levels of ANP, cyclic guanosine monophosphate, glomerular filtration rate, and respiratory index, and significantly lower levels of renin, angiotensin-II, aldosterone, and pleural effusion, as compared with the non-hANP group. The dosage of furosemide was significantly lower and the urine volume was significantly larger in the hANP group. CONCLUSIONS: hANP can satisfactorily compensate for the shortcomings of CPB by decreasing the peripheral vascular resistance, suppressing the renin-angiotensin-aldosterone system, and exerting a strong diuretic effect.

Atrial Natriuretic Factor↗

PubMed2000

Clinical results of coronary artery bypass grafting with use of the internal thoracic artery under low free flow conditions.

OBJECTIVE: Even when left internal thoracic artery flow is very low, we have used the artery for grafting without any further maneuvers. In this study, we investigated the clinical results of coronary bypass surgery using the left internal thoracic artery with low free flow. METHODS: A total of 163 patients were divided into 2 groups: group L (n = 43) had free flow of 20 mL/min or less and group H (n = 120) had free flow of more than 20 mL/min. We performed a comparative study on the basis of coronary angiography and pulsed Doppler echocardiography. Furthermore, 12 months' postoperative graft angiography was carried out in 11 patients from group L. RESULTS: No patient had low output syndrome or perioperative myocardial infarction. One month after the operation, 3 cases of graft occlusion and 9 cases of the "string sign" were identified in group H. However, group L had no graft occlusion and only 1 case of the "string sign." The 1-month postoperative Doppler echocardiographic study showed no significant differences in the diastolic fraction of velocity time integrals and the diastolic/systolic peak velocity ratio of the grafts. In the 11 patients undergoing angiography after 1 year, graft patency was excellent. Moreover, the graft diameter was significantly larger than it was 1 month after the operation. CONCLUSION: These results suggest that the left internal thoracic artery can be used for coronary artery bypass grafting even when the flow is less than 20 mL/min.

Blood Flow Velocity↗

PubMed2000

A clinical use of the Kyocera Gyro C1E3 centrifugal pump.

The Kyocera Gyro C1E3 centrifugal blood pump was clinically applied for a cardiopulmonary bypass (CPB) of coronary artery bypass grafting (CABG). The patient was 72-year-old male with postinfarction unstable angina. The surgery was carried out on November 20, 1998. The air inside the pump was easily and quickly removed, and its controllability was excellent. The pump flow during operation was maintained 2.2 L/m2. Total CPB time was 173 min. Perioperative parameters of hemolysis and cytotoxicity were not remarkably changed. Macroscopically and microscopically, there were no thrombi inside the pump after usage. This is the first reported case of clinical use of the Kyocera Gyro C1E3 pump.

Aged↗

PubMed2000

Jostra Rota Flow RF-30 pump system: a new centrifugal blood pump for cardiopulmonary bypass.

The Rota Flow pump is a fully integrated centrifugal pump system in the Jostra heart-lung machine HL-20 with features such as a less friction mono-pivot bearing system, sealless pump housing, and spiral housing. To evaluate its biocompatibility, antithrombogenesity, and hemolysis, we used it as a main pump of cardiopulmonary bypass (CPB) in coronary artery bypass grafting (CABG) cases and compared it with the BioMedicus pump. From February 1999 to May 1999, 30 consecutive patients underwent CABG under conventional CPB. Fifteen cases were supported by the Rota Flow RF-32 (Group R), and the remaining 15 were pumped by the BioMedicus BP-80 (Group B). In both groups, the flow rate was controlled in an equivalent value. Blood sampling was as follows: preoperative, 60 min after, postoperative Days (POD) 0, 1, and 2. We evaluated the plasma free hemoglobin (fHb) as the hemolysis parameter, beta-thromboglobulin (beta-TG) and platelet factor IV (PF-4) as the platelet deterioration index, C3, C4, and CH50 as complement activation, coagulation function, fibrinolytic factor and thrombomodulin, nitric oxide (NO), and endothelin as endothelial deterioration. This system was very easily and simply controlled and had excellent response. Perioperative laboratory data were not markedly changed in either group. The Rota Flow demonstrated equivalent value of biocompatibility and hemolysis as compared with the BioMedicus BP-80, which is a standard centrifugal pump. After pumping, no thrombus formation or pivot wear was observed inside the pump. This atraumatic, small centrifugal pump is suitable not only for CPB but also for long-term circulatory support.

Analysis of Variance↗

PubMed2000

Strategy of circulatory support with percutaneous cardiopulmonary support.

We evaluated the efficacy and problems of circulatory support with percutaneous cardiopulmonary support (PCPS) for severe cardiogenic shock and discussed our strategy of mechanical circulatory assist for severe cardiopulmonary failure. We also described the effects of an alternative way of PCPS as venoarterial (VA) bypass from the right atrium (RA) to the ascending aorta (Ao), which was used recently in 3 patients. Over the past 9 years, 30 patients (20 men and 10 women; mean age: 61 years) received perioperative PCPS at our institution. Indications of PCPS were cardiopulmonary bypass weaning in 13 patients, postoperative low output syndrome (LOS) in 14 patients, and preoperative cardiogenic shock in 3 patients. Approaches of the PCPS system were the femoral artery to the femoral vein (F-F) in 21 patients, the RA to the femoral artery (RA-FA) in 5 patients, the RA to the Ao (RA-Ao) in 3 patients, and the right and left atrium to the Ao in 1 patient. Seventeen (56.7%) patients were weaned from mechanical circulatory support (Group 1) and the remaining 13 patients were not (Group 2). In Group 1, PCPS running time was 33.1 +/- 13.6 h, which was significantly shorter than that of Group 2 (70.6 +/- 44.4 h). Left ventricular ejection fraction was improved from 34.8 +/- 12.0% at the pump to 42.5 +/- 4.6% after 24 h support in Group 1, which was significantly better than that of Group 2 (21.6 +/- 3.5%). In particular, it was 48.6 +/- 5.7% in the patients with RA-Ao, which was further improved. Two of 3 patients with RA-Ao were discharged. Thrombectomy was carried out for ischemic complication of the lower extremity in 5 patients with F-F and 1 patient with RA-FA. One patient with F-F needed amputation of the leg due to necrosis. Thirteen patients (43.3%) were discharged. Hospital mortality indicated 17 patients (56.7%). Fifteen patients died with multiple organ failure. In conclusion, our alternate strategy of assisted circulation for severe cardiac failure is as follows. In patients with postcardiotomy cardiogenic shock or LOS, PCPS should be applied first under intraaortic balloon pumping (IABP) assist for a maximum of 2 or 3 days. In older aged patients particularly, the RA-Ao approach of PCPS is superior to control flow rate easily, with less of the left ventricular afterload and ischemic complications of the lower extremity. If native cardiac function does not recover and longer support is necessary, several types of ventricular assist devices should be introduced, according to end-organ function and the expected support period.

Adolescent↗

PubMed2000

Removal of a chronically infected bipolar pacemaker electrode: a successful case report.

A chronic infected bipolar pacemaker electrode with a fin tip was successfully removed 7 years and 9 months after its original implantation from a 72-year-old Japanese man, using the Cook pacemaker lead extraction system. The locking stylet could not advance to the lead tip over the positive pole because of firm adhesions. Because the scar tissue between the positive pole and myocardium could not be freed by the inner sheath, it was disrupted by the slanted end of the outer sheath. The firmest adhesion was on the positive pole, not on the fin tip. The complete extraction success rate of bipolar tined or fin leads is worse than for other types of leads. When extracting a bipolar pacemaker lead, dissection of the positive pole from scar tissue should be taken into account in addition to the lead tip. Rotating the slanted end of the outer sheath is a useful technique when dissecting firm adhesions.

Aged↗

PubMed2000

Mid-term results of ATS open pivot bileaflet mechanical prosthetic heart valve.

We investigated mid-term results of the patients with an ATS bileaflet valve in our institution. In the past 6 years, 69 patients received valve replacement with an ATS valve. We assessed the changes of serum lactate dehydrogenase (LDH) level in the hospital, and the valve's closing sound. The serum LDH level had almost normalized one week postoperatively and they have maintained normal levels since then. According to the questionnaire about the valvular sound at a random period after surgery, it was unnoticeable in 61 (88.4%) of the patients with ATS valve. In the 8 patients (12.6%) who recognized the valve sound, 7 of them were reoperation cases. As to the frequency analysis for the valve's closing sound, the sound peak was indicated at around 1.2 kHz in the patients with ATS valves. In patients with St. Jude Medical (SJM) valves, it appeared not only around 1.2 kHz but also around 2 to 7 kHz. Postoperative cerebral infarction was complicated in one patient. Mortality occurred in 4 (5.7%) of the patients with ATS valves. The follow up periods were from one to 66 months. Thromboembolic event free and actuarial survival rate in the patients with ATS valves were 98.6% and 94.2%, respectively. These results indicated that the ATS valve is considered to be a safe valve and mid-term follow-up shows excellent results in terms of the patients quality of life.

Female↗

PubMed2000

Closure of calcified patent ductus arteriosus.

Patent ductus arteriosus (PDA) in adults is occasionally associated with calcification and pulmonary hypertension, for which an anterior approach through a median sternotomy with cardiopulmonary bypass is often used. Sutures are placed without circulatory arrest by using a transpulmonary balloon catheter as an occluder. To secure the suture tie, we used Nélaton's catheters as tourniquets.

Calcinosis↗