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Biomedical subjects

R Tominaga

Publications and source records attributed to R Tominaga.

At least 73 records · Page 4Linked to original sources
PubMed1994

The risks of reoperation for prosthetic valve dysfunction.

A retrospective study was conducted on 124 patients who underwent re-replacement of previously implanted prosthetic heart valves for structural valve failure, prosthetic valve endocarditis, periprosthetic leak, a thrombosed valve, hemolysis, or prophylactic removal. In total, 85% of the explanted valves were bioprostheses, and 70% of the newly implanted valves were mechanical valves. The overall operative mortality rate was 8.1%, being 3.2% of 95 single valve recipients and 25.0% of 28 double valve recipients (P < 0.001). The overall mortality rate dropped from 13.6% of 66 patients before 1988, to 1.7% of 58 patients encountered in the last 3 years (P < 0.02). Since 1988, a third of the patients have undergone reoperation without homologous blood transfusion. A univariate analysis revealed eight operative risk factors, namely: higher values of preoperative blood urea nitrogen or total bilirubin, double valve replacement at the redo operation, NYHA class IV, urgency of reoperation, a duration of implantation of less than 3 months, reoperation in the earlier period of this study, and reexploration for bleeding or cardiac tamponade after re-replacement surgery. A multivariate statistical analysis demonstrated that preoperative blood urea nitrogen, urgency of reoperation, double valve replacement, and the duration of implantation were independent risk factors. Thus, we recommend that surgery be performed early, before the occurrence of other organ failure induced by congestive heart failure due to any form of valve dysfunction.

Adolescent↗
PubMed1994

Chronic nonpulsatile blood flow. I. Cerebral autoregulation in chronic nonpulsatile biventricular bypass: carotid blood flow response to hypercapnia.

To investigate the response of the carotid blood flow and general circulation to hypercapnia in chronic nonpulsatile blood flow, we performed 18 carbon dioxide gas inhalation studies on three calves undergoing a centrifugal biventricular bypass with ventricular fibrillation. An ultrasonic flow probe was put on the carotid artery during biventricular bypass pump implantation, and pump flows were maintained at 90, 100, and 120 ml/kg per minute for 1 week each. The carbon dioxide inhalation studies were performed twice a week. Hypercapnia was induced by administering pure carbon dioxide gas through a nasal tube at flow rates of 0, 5, 7.5, 10, 12.5, and 15 L/min for 5 minutes each at three different nominal pump flow rates, and the resultant arterial blood gas and hemodynamic changes were recorded. No significant correlation existed between the carotid blood flow and mean aortic pressure, which varied from 70 to 140 mm Hg, but the carotid blood flow correlated significantly (p < 0.01) with the systemic pump flow rate. A significant (p < 0.01) linear relationship was found between the carotid blood flow and arterial carbon dioxide tension. For each 1 mm Hg change in arterial carbon dioxide tension, there was a 2.8 % change in the carotid blood flow. The percent changes in the carotid blood flow in response to arterial carbon dioxide tension were calculated as 2.9%, 3.7%, and 2.5% for each 1 mm Hg change in arterial carbon dioxide tension at pump flows of 90, 100 and 120 ml/kg per minute. No significant differences in the carotid blood flow response to hypercapnia were detected among the three systemic pump flow rates. These results thus suggested that chronic nonpulsatile blood flow had no detrimental effects on cerebral autoregulation.

Animals↗
PubMed1993

Effects of stent design and serum cholesterol level on the restenosis rate in atherosclerotic rabbits.

We investigated the effect of serum cholesterol level and stent design on the restenosis rate within the stent after balloon angioplasty and stent implantation using atherosclerotic rabbits. Two types of nickel/titanium stents with gaps (open stent) and without gaps (closed stent) between the wire coils were implanted into the aorta of the rabbits 10 weeks after atherosclerosis had been induced using a standard high cholesterol diet and balloon abrasion. Each rabbit had an open stent and a closed stent implanted into the infrarenal abdominal aorta. Between these two stents a control segment of the aorta was treated with angioplasty alone. The animals were divided into two groups according to the diet protocol as follows: in group I (n = 9) a high cholesterol diet was stopped after stent implantation; in group II (n = 10) a high cholesterol diet was maintained after stent implantation. Digital subtraction angiograms were obtained every 4 weeks for up to 24 weeks and the narrowest diameter of the arterial segments within each stent and in the segment between stents was measured. The diameter narrowing within the closed stent was greater in the high cholesterol group compared with the low cholesterol group: 12 weeks (2.57 +/- 0.09 mm in group I vs 2.14 +/- 0.15 mm in group II, mean +/- S.E., p < 0.05); 16 weeks (2.55 +/- 0.09 mm vs 2.14 +/- 0.12 mm, p < 0.05); 20 weeks (2.59 +/- 0.06 mm vs 1.98 +/- 0.12 mm, p < 0.01); and 24 weeks (2.45 +/- 0.11 mm vs 2.01 +/- 0.11 mm, p < 0.05). No significant differences in the narrowest diameter of the arterial segments were observed between high and low cholesterol groups in the angioplasty alone areas or within the open stents. There was a significant difference in the narrowest diameter between stents with versus those without gaps (at 12, 16, and 20 weeks poststenting in group I and at 4, 8, 12, 16, 20, and 24 weeks in group II). Thus the stent with the least metal is correlated with less stenosis and intimal hyperplasia. From these data we conclude that both stent design and serum cholesterol are important factors for restenosis after stent implantation.

Angioplasty, Balloon, Coronary↗
PubMed1993

Revised technique of cardiopulmonary bypass in one-stage repair of interrupted aortic arch complex.

Twenty infants with interrupted aortic arch associated with various intracardiac anomalies underwent primary complete repair using pulsatile high-flow cardiopulmonary bypass with a short period of circulatory arrest. Age at repair ranged from 11 to 126 days (mean age, 43 days). Weight ranged from 2.2 to 5.5 kg (mean weight, 3.4 kg). Associated cardiac lesions included ventricular septal defect (14 patients), truncus arteriosus (3), transposition of the great arteries (2), and aortopulmonary window (1 patient). Left ventricular outflow tract obstruction was relieved in 2 patients. The aortic arch was reconstructed with a polytetrafluoroethylene graft in 7 patients and by direct anastomosis in the most recent 11 patients. An arterial cannulation method has been devised to facilitate direct anastomosis between the ascending aorta and the descending aorta, to lessen circulatory arrest time, and to prevent dangerous laceration and postoperative narrowing of the thin, small ascending aorta at the cannulation site. Two patients died, a surgical mortality rate of 10%. There has been one late death, which was due to severe truncal valve insufficiency. The other patients are doing well with a mean follow-up of 3 years 6 months. Restenosis of the direct anastomosis has not been noted in any patient. However, subaortic stenosis with pressure gradients of 30 to 40 mm Hg developed in 3 patients. In conclusion, one-stage repair including direct anastomosis for the aortic arch reconstruction and repair of all coexisting intracardiac defects is thought to be the treatment of choice.

Anastomosis, Surgical↗
PubMed1993

[Clinical assessment of complement activation and leukocyte kinetics during cardiopulmonary bypass: the effect of cepharanthine].

Complement activation and leukosequestration to the lung was studied during cardiopulmonary bypass in eleven patients undergoing cardiac operation without blood transfusion. Six patients (group I) received methylprednisolone before and after the bypass, and the other five (group II) received cepharanthine (biscoclaurin alkaloid) before the bypass associated with methylprednisolone therapy. Leukosequestration to the lung was observed at the time of reperfusion of the lung only in group I, although complement activation estimated by the increase of C 4 a and C 3 a was quite similar in both group. Cepharanthine prevented the sequestration of the leukocyte to the lung may be by its membrane stabilizing effect.

Adult↗
PubMed1992

Endo-xyloglucan transferase, a novel class of glycosyltransferase that catalyzes transfer of a segment of xyloglucan molecule to another xyloglucan molecule.

Xyloglucans are the major component of plant cell walls and bind tightly to the surface of individual cellulose microfibrils, thereby cross-linking them into a complex polysaccharide network of the cell wall. The cleavage and reconnection of xyloglucan cross-links are considered to play the leading role during chemical processes essential for wall expansion and, therefore, cell growth and differentiation. Although it is hypothesized that some transglycosylation is involved in these chemical processes, the enzyme responsible for the reaction was not identified. We have now purified a novel class of endo-type glycosyltransferase to apparent homogeneity from the extracellular space or the cell wall of the epicotyls of Vigna angularis, a bean plant. The enzyme is a glycoprotein with a molecular mass of about 33 kDa. The enzyme catalyzes both 1) endo-type splitting of a xyloglucan molecule and 2) linking of a newly generated reducing end of the xyloglucan to the nonreducing end of another xyloglucan molecule, thereby mediating the transfer of a large segment of the xyloglucan to another xyloglucan molecule. The transferase exhibits no glycosidase or glycanase activity. Substrate specificity of the enzyme was investigated using several polysaccharides with different glycosidic linkages as donor substrates and pyridylamino oligosaccharides as acceptor substrates, in which the reducing end of the carbohydrate was tagged with a fluorescent group. The enzyme required a basic xyloglucan structure, i.e. a beta-(1-->4)-glucosyl backbone with xylosyl side chains, for both acceptor and donor activity. Galactosyl or fucosyl side chains on the main chain were not required for the acceptor activity. The enzyme exhibited higher reaction rates when xyloglucans with higher M(r) were used as donor substrates. Xyloglucans smaller than 10 kDa were no longer the donor substrate. On the other hand, pyridylamino heptasaccharide acted as a good acceptor as did xyloglucan polymers. Based on these results we propose to designate this novel enzyme a xyloglucan: xyloglucano-transferase, to be abbreviated endo-xyloglucan transferase (EXT) or xyloglucan recombinase. This enzyme is the first enzyme identified that mediates the transfer of a high M(r) segment between polysaccharide molecules to generate chimeric polymers. We conclude that endo-xyloglucan transferase functions as a reconnecting enzyme for xyloglucans and is involved in the interweaving or reconstruction of cell wall matrix, which is responsible for chemical creepage that leads to morphological changes in the cell wall.

Carbohydrate Sequence↗
PubMed1992

Effects of design geometry of intravascular endoprostheses on stenosis rate in normal rabbits.

To investigate the effects of gaps between the individual wire coils of a shape memory Nitinol alloy intravascular endoprosthesis, 20 stents with and without gaps were implanted transluminally into the infrarenal abdominal aortas of 10 normal rabbits after balloon angioplasty. Digital subtraction angiography (DSA) was done at 4, 12, 16, 20, and 24 weeks after stent implantation to examine the stenosis rate and major side branch patency. Stenosis rate within stents with gaps were significantly lower than those without gaps: 8.1 +/- 5.0% versus 15.0 +/- 6.8% at 12 weeks, 13.6 +/- 6.0% versus 26.0 +/- 9.4% at 24 weeks by DSA, p greater than 0.005 and p less than 0.01 respectively. The maximum and mean neointimal thickness measured histologically at the time of animal death correlated significantly to the narrowest diameter obtained from the DSA studies, (r = 0.84 and r = 0.79, respectively, p less than 0.01). Greater hyperplasia of the neointima was evident in the stented arterial segments with stents without gaps compared with those with gaps (83 +/- 22 versus 187 +/- 46 microns mean thickness, p less than 0.001). The patency rate of the side branches in the stented arterial segment was significantly (p less than 0.05) higher in stents having gaps. These results suggest that the placement of gaps between wire pitches reduced the neointimal thickness within stents and prevented the obstruction of arterial side branches.

Angioplasty, Balloon↗
PubMed1992

Eleven-year follow-up study of aortic or aortic-mitral anulus-enlarging procedure by Manouguian's technique.

Although Manouguian's operation is well established, there have been little long-term data published on its outcome. From January 1980 to June 1988, 15 patients underwent patch enlargement of the small aortic anulus by Manouguian's approach, either with aortic single valve replacement (7 patients) or with aortic-mitral double valve replacement (8 patients). Follow-up ranged from 3.0 to 11.4 years (mean 8.5) and was completed with a cumulative total of 102 patient-years. One patient died of fulminant hemolysis, probably related to turbulent jet flow and Dacron patch material (operative mortality 6.7%). There were four late deaths, and the actuarial survival, including operative death at 10 years, was 62% +/- 14%. Reoperations were performed seven times in six patients. Most of these complications were not considered to be caused by the anulus-enlarging procedure. Actuarial freedom rate from reoperation at 10 years was 65% +/- 15%. Four patients underwent rereplacement of prostheses for Hancock valve failure during 2.9 to 11.3 years (mean 8.2 years). The anulus enlargement was found to be well healed and presented no problem during reoperation. Surgically induced mitral regurgitation by Manouguian's procedure was observed in two patients. The regurgitation did not progress during follow-up duration of 1.9 to 10.0 years, nor did it cause congestive heart failure. Annular enlargement by Manouguian's procedure with use of mechanical valves is one of the good selections in patients with the narrow aortic valve ring.

Actuarial Analysis↗
PubMed1992

Excellent durability of the Hancock porcine bioprosthesis in the tricuspid position. A sixteen-year follow-up study.

From February 1975 to August 1981, 23 consecutive patients underwent tricuspid valve replacement, which was either isolated (six patients) or combined with the replacement of other valves (17) by means of a standard, glutaraldehyde-preserved Hancock porcine bioprostheses. Patients' ages ranged from 9 to 53 (mean 36.2) years. The follow-up period ranged from 0.2 to 16.5 years (mean 9.1) and was complete in 100% of all cases. Structural valve failure of the tricuspid Hancock valve was noticed in two patients, a 9-year-old boy and a 13-year-old girl 3.4 and 16.5 years after implantation, respectively. The actuarial freedom rate from structural valve failure at 10 years was 94 +/- 6%. There were six tricuspid prosthesis-related events: structural valve failure in two and valve thrombosis, anticoagulant-related bleeding, prosthetic valve endocarditis, and periprosthetic leak in one each, respectively. The actuarial freedom from these events at 10 years was 78 +/- 10%. Five pairs of aortic/mitral-tricuspid Hancock valves were explanted simultaneously from the same patients after 8.1 to 13.9 (mean 11.4) years postoperatively. A gross examination showed no valve dysfunction in the explants from the tricuspid position, but degenerative changes with valve dysfunction in those from the mitral and aortic position were observed (none of five versus five of seven; p < 0.03). We concluded that the selection of a Hancock bioprosthesis in the tricuspid position is acceptable because of the low incidence of prosthesis-related complications and the excellent durability of more than 10 years.

Actuarial Analysis↗
PubMed1992

More than ten years' follow-up of the Hancock porcine bioprosthesis in Japan.

From February 1975 through October 1981, 256 Hancock porcine bioprostheses (Johnson & Johnson Cardiovascular, King of Prussia, Pa.) (60 aortic, 169 mitral, and 27 pulmonary/tricuspid position) were implanted in 220 patients (104 male and 116 female, aged 9 to 67 years; mean 43.3) at Kyushu University Hospital in Japan. The procedures include 41 aortic valve replacements, 121 mitral valve replacements, 4 pulmonary valve replacements, 6 tricuspid valve replacements, and 48 combined valve replacements (31 aortic plus mitral, 13 mitral plus tricuspid, and 4 aortic plus mitral plus tricuspid). Hospital mortality was 6.4%. Follow-up was 98% during 8 to 14 (mean 10.5) years. Cumulative follow-up was 1836 patient-years and 2078 valve-years. At 10 years the overall actuarial survival rate, including hospital morality, was 70% +/- 3%, and freedom from valve-related mortality with sudden death was 87% +/- 3%. More than half of the current survivors required no anticoagulant therapy. Freedom from thromboembolism or anticoagulant-related hemorrhage (or both) and prosthetic valve endocarditis was common. Freedom from structural valve failure and reoperation declined more than 9 years after replacement of left-sided heart valves but not after replacement of right-sided heart valves. Sixty-seven patients underwent 68 repeat operations, and there were four deaths (5.9%). The rate of freedom from overall valve-related complications at 10 years was 62% +/- 8% for aortic valve replacement, 53% +/- 5% for mitral valve replacement, 80% +/- 13% for pulmonary/tricuspid valve replacement, and 42% +/- 9% for combined valve replacement. There was a significant difference between pulmonary/tricuspid valve replacement and combined valve replacement (p less than 0.05). The Hancock bioprosthesis is suitable for the replacement of valves in the right side of the heart but not for combined valve replacement.

Actuarial Analysis↗
PubMed1991

Comparative study between valve repair and replacement for mitral pure regurgitation--early and late postoperative results.

From May 1975 through December 1988, 91 patients (mean age 50.4 +/- 12.8 years) had first-time surgery for mitral pure regurgitation; 48 had mitral valve replacement (MVR) and 43 had valve repair. A majority of the patients had non-rheumatic valvular diseases. Those patients who underwent repair had less hemodynamic and functional derangement than those who underwent MVR. The operative mortality was 8.3% in the MVR group and 2.3% in the repair group. Seventeen percent of the MVR group and 2% of the repair group required intra-aortic balloon pumping support (p less than 0.03). A higher dose of dopamine and/or dobutamine during the early postoperative period was necessary in the MVR group (7.0 +/- 4.8 micrograms/kg/min) than in the repair group (5.1 +/- 3.1 micrograms/kg/min). Duration of respirator support for hospital survivors was longer in the MVR group (2.3 +/- 2.7 days) than in the repair group (1.4 +/- 1.0 days). There were 5 late deaths (2.2 +/- 1.0%/pt-yr) not counting 6 non-cardiac deaths in the MVR group and 1 (0.6 +/- 0.6%/pt-yr) in the repair group. There were 17 patients (7.5 +/- 1.8%/pt-yr) who experienced treatment failure in the MVR group and 5 (2.3 +/- 1.3%/pt-yr) in the repair group (p less than 0.02). Eight patients in the MVR group (3.5 +/- 1.3%/pt-yr) underwent repeat surgery in the late postoperative period, as did 3 (1.7 +/- 1.0%/pt-yr) in the repair group. There was no increase in the incidence of repeat surgery after valve repair. All the current survivors in the repair group, and 96% of those in the MVR group were in NYHA functional class I or II. These results indicate that mitral repair is the preferred operative procedure for pure mitral regurgitation, whenever it is possible.

Actuarial Analysis↗
PubMed1991

Comparative study between St. Jude Medical and bioprosthetic valves in the right side of the heart.

Comparative long-term performance characteristics of St. Jude Medical (SJM) and bioprosthetic valves were conducted retrospectively for patients who underwent prosthetic valve replacement in the right side of the heart from 1975 to 1988. Fifty-four patients received either SJM (n = 18) or bioprosthetic (n = 37) valves. The cumulative follow-up for SJM valves was 91 valves-years (range 3.9 to 7.2 years) and that for bioprostheses was 282 valve-years (range 1.3 to 14.8 years). Follow-up rate was 100%. The actuarial survival rate excluding hospital deaths at 5 years was 81 +/- 10% for SJM and 97 +/- 3% for bioprosthetic valve recipients (p = ns). The rates of freedom from thrombosis or anticoagulant-related hemorrhage, structural valve failure, prosthetic valve endocarditis, reoperation, and overall valve-related complications at 5 years were 72 +/- 11%, 100%, 100%, 83 +/- 9%, and 72 +/- 11% for SJM valve recipients, and 100%, 97 +/- 3%, 97 +/- 3%, 94 +/- 4%, and 94 +/- 4% for bioprosthetic valve recipients, respectively. Structural valve failure, prosthetic valve endocarditis and reoperations occurred at a similar incidence in each of the two types of prostheses. Thrombosis and overall valve-related events occurred more frequently in SJM valve recipients (5.5 +/- 2.5 vs 0%/valve-year; p less than 0.02, 6.6 +/- 2.7 vs 1.1 +/- 0.6 %/valve-year; p less than 0.03, respectively). The bioprosthetic valve which did not need warfarin anticoagulation therapy had low incidence of valve-related complications and showed good long-term durability even in the younger age group. The bioprosthetic valve was superior to the SJM valve in the right side of the heart.

Actuarial Analysis↗
PubMed1991

[Recommendation for open heart surgery in infancy].

Progress in infant open-heart surgery last 10 years was reviewed mainly based on the surgical experiences in Fukuoka Children's Hospital. Recent advances and present problems in patient's care, cardiopulmonary bypass methods and cardioplegia were discussed. Low surgical mortality of 4.8% in 245 infant open-heart repairs between 1988 and 1990 in Fukuoka is highly suggestive of early primary repair for most of congenital heart diseases.

Cardiac Surgical Procedures↗
PubMed1991

[Postoperative complications and treatments after Bentall operation].

Postoperative complications of Bentall operation for the annuloaortic ectasia have frequently occurred, although the mortality has been reduced. To reduce complications after Bentall operation we have taken three major treatments since 1987. The first was reimplantation technique of coronary ostia in replacing the ascending aorta and the aortic valve with a tube graft. The second was the infusion technique of cardioplegic solution such as retrograde cardioplegia infusion. The third method was to save blood and reduce the blood transfusion by preserving autoblood preoperatively and using cell saving machine. The purpose of this study was to analyse 20 patients who underwent the Bentall procedure and to investigate the effect of our treatments in Bentall operation on the operative results. We divided our patients into two groups. Fourteen patients in the group 1 were operated before 1987, when our principles were not performed. Six patients in group II were operated under the principles mentioned above. There were no differences in cardiopulmonary bypass time and ischemic time between group I and II. Transfused blood volume in group II was remarkably less than that of group I. Postoperative complications occurred in all patients in group I (100%), while three patients in group II (50%) had complications (p less than 0.05). We, hence, conclude that our method could be useful for reducing postoperative complication rate in Bentall operation.

Adolescent↗
PubMed1991

Novel method of valve replacement with interrupted sutures using protractor rings for the partitioning of a prosthetic sewing ring.

Newly devised protractor rings that can equally partition a prosthetic valve sewing ring into 10-20 acrs have been used on 46 patients who underwent 59 aortic, mitral, and/or tricuspid valve replacement. After an appropriate number of interrupted mattress sutures were placed along the host annulus, one of the 11 protractor rings was chosen and used to copy the partition onto the sewing ring with a tissue pen. The interrupted mattress sutures kept on a suture holder were then passed through the prosthetic sewing ring directly from one end to the other. Based on ex vivo experiments in simulating valve replacement, it was evident that time required for placing sutures around the sewing ring was significantly shortened by the use of such protractor rings. The use of these protractor rings may thus be useful in decreasing valve replacement time as well as in potentially simplifying operative procedures.

Blood Vessel Prosthesis↗