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Biomedical subjects

H Koyanagi

Publications and source records attributed to H Koyanagi.

At least 19 recordsLinked to original sources
PubMed1992

An anatomical study of a new method for enlargement of narrowed aortic annulus: intra-arterial aorto-infundibuloplasty.

A new procedure "intraarterial aorto-infundibuloplasty" for the narrowed aortic annulus is described. Aortic valve replacement is performed through an aorto-pulmonary and infundibular septal incision which is eventually enlarged by a single patch, i.e., a two-dimensional patch instead of a three-dimensional patch as in Konno's procedure. An anatomical study showed that a prosthetic valve three sizes larger than the natural annular diameter could be implanted and the natural annular diameter was increased by as much as 42%.

Animals↗
PubMed1992

Perfusion of dominant left subclavian artery during thoracic aortic aneurysm operation.

A case of aneurysm of the descending thoracic aorta with dominant left vertebral artery and poor cross-collateral circulation is reported. We believe that in such a patient perfusion of the dominant left subclavian artery is a safe method to prevent vertebrobasilar ischemia during thoracic aortic aneurysm operation under normothermia.

Aorta, Thoracic↗
PubMed1992

Na+ effects on intracellular pH of isolated, perfused rabbit gastric mucosal surface cells.

The effects of extracellular Na+ on intracellular pH were studied by perfusing BCECF loaded gastric mucosal surface cells adherent to glass coverslips held in a spectrophotofluorometer. Removal of Na+ from a NaCl Ringer perfusate (pH 7.4) resulted in progressive intracellular acidification, which was partially blocked by amiloride. An H+ conductance did not appear to be present. Acidification induced either by Na+ removal or by a NH4 prepulse was reversed by extracellular Na+, but this effect was not completely prevented by amiloride. Amiloride significantly, but not completely, inhibited Na22 uptake by gastric mucosal surface cells. The data suggest that extracellular Na+ maintains intracellular pH of gastric mucosal surface cells through amiloride-sensitive and -insensitive pathways. In the absence of extracellular Na+, cellular acidification seemed to be partially due to Na+/H+ exchange.

Amiloride↗
PubMed1992

[Clinical experiences of a new vascular graft prosthesis fabricated from ultrafine polyester fiber (Toray graft)].

A new low porous vascular prosthesis made of a textile of ultra-fine fiber was used clinically in ten patients for whom replacement of the ascending and/or arch aorta were performed. There were no operative deaths after initial operations, but one patient died after a second operation in which replacement of the thoraco-abdominal aorta was performed. Nine survived patients are well for 50 days to 10 months postoperatively. The new vascular graft prosthesis was very soft and pliable in clinical use, and the surgical needle penetrates easily the prosthesis. Although the new graft prosthesis can be used without preclotting under full heparinization, porosity of the graft, 100 ml/min/cm, revealed initial oozing of blood for a while just after releasing an aortic clamp. Therefore, preclotting of the graft is recommended under full heparinization. Because of rapid, even, and stable formation of neo-intima in the new graft confirmed by experimental studies of Noishiki et al., and soft and pliable characteristics of the graft, a wide-spread clinical use of the new graft is recommended in the surgery of aortic aneurysms as well as reconstruction of the congenital malformations.

Adult↗
PubMed1992

[Long-term results in 1,400 patients with coronary artery bypass grafting: saphenous vein vs arterial grafts].

To analyze and compare the effects of saphenous vein grafts (SVG) and arterial grafts (AG) on the long-term results of the coronary artery bypass grafting (CABG), retrospective nonrandomized studies were performed in 1,400 consecutive patients with CABG in terms of reoperation, postoperative transluminal coronary angioplasty (PTCA) to the grafts, actuarial survival rate, and cumulative event free rate. AG was used frequently in recent cases in which more diffuse and multiple vessel disease were encountered. No statistically significant differences were noted in any of the reoperation free rate, actuarial survival rate, success rate of the PTCA, and cumulative event free rate between SVG and AG, because the long-term results of the SVG was apparently better than reported Caucasian's long-term results, while those of the AG were as good as Caucasian's. Reoperation and PTCA for the AG were performed less than one year after the CABG in most cases and restenosis after the PTCA was rare. In contrast, those for the SVG were mainly done late postoperative period, and the incidence of the restenosis after the PTCA was very high. These results indicated that the main cause of the graft failure in the AG was technic-related, and that of the SVG was graft's atherosclerosis. We conclude from this study that AG should be indicated more extensively than SVG, but proper indication and application of the AG in various situations and technical improvement to avoid stenosis at anastomosis are important to improve the long-term results of the CABG.

Adolescent↗
PubMed1992

[Sequential coronary artery bypass using gastroepiploic artery].

We carried out sequential coronary bypass grafting using the gastroepiploic artery (GEA) as an in situ graft in seven patients. Four patients had sequential graft from the right coronary to the circumflex. Three patients were anastomosed to two or three peripheral branches of the right coronary artery. There were no early deaths. Postoperative angiograms revealed that the patency rate was 92.3% (12/13 anastomoses). Sequential GEA grafting is available to anastomose the peripheral branches of the right coronary and the circumflex where the in situ internal thoracic artery is difficult to access. Therefore, this procedure will be indicated for multiple coronary artery bypass grafting.

Aged↗
PubMed1992

[Surgical versus nonsurgical therapy of fatal tachyarrhythmias].

Interventional treatment is necessary for fatal drug-refractory tachyarrhythmias. Thirty-three, 33 and 16 patients (pts) with intractable ventricular tachycardia (VT) and/or fibrillation (VF) were managed with cryosurgery (CS), electrical catheter ablation (EA) and implantable pacer-cardioverter-defibrillator (PCD), respectively. Seventy-six and 43 pts with sudden death risk in the Wolff-Parkinson-White syndrome (WPW) also underwent CS and EA, respectively. CS success rates were 85% in VT/VF and 95% in WPW. Those of EA were 48% and 81%, respectively. EA success rates were 100% (6/6) in idiopathic verapamil-sensitive VT originated from LV, 0% (0/2) in VT following TOF repair and 0% (0/2) in idiopathic VT originated from right ventricular outflow tract. A new VT developed in 5 of 11 pts with arrhythmogenic right ventricular dysplasia (ARVD) following EA. PCD was effective for prevention from sudden death in idiopathic VF and pleomorphic VT. All of pharmacologic, EA and CS therapies were relatively effective in ischemic heart disease without low EF. In conclusion, the decision of VT-VF therapy may be affected by the underlying heart disease and EA may be established as an initial intervention for high risk WPW.

Adult↗
PubMed1992

In vivo protein adsorption on polymers: visualization of adsorbed proteins on vascular implants in dogs.

The absorption of plasma proteins is an important event at the blood-material interface, and strongly affects subsequent cellular interaction and thrombus formation. Although considerable efforts have been expended to elucidate the mechanism of protein adsorption and the role of absorbed protein layer at the blood-material interface, there has been little knowledge of how the initial adsorbed proteins are maintained or changed in a time-variant process in in vivo long-term implantation. In this study, we described detailed analyses concerning the characterization of adsorbed proteins on HEMA--styrene block copolymer surfaces (HEMA-st) and poly(ethylene oxide) (PEO) grafted Biomer (B-PEO4K) for in vivo long-term canine vascular graft implants as well as in vitro short-term experiments. Biomer vascular grafts (6 mm I.D., 7 cm in length) were fabricated by a dip coating and the luminal surface was modified with PEO grafting, HEMA-st coating, or Biomer coating (control). These surface modified grafts were recirculated for different time intervals (5, 15, 30, 60 and 120 min) using citrated canine whole blood. The grafts were then implanted in the abdominal aortas of dogs and evaluated for graft patency and protein adsorption. The adsorbed proteins (albumin, IgG and fibrinogen) were quantified using an in situ radioimmunoassay. Surface protein layer thickness was measured by transmission electron microscopy (TEM). Visualization of absorbed plasma proteins (albumin, IgG and fibrinogen) was performed with TEM using an immunoperoxidase double antibody technique. In in vitro recirculation systems, albumin and IgG showed similar Langmuir type pattern onto all test surfaces. On B-PEO4K surfaces, fibrinogen adsorption kinetics demonstrated 'Vroman effect'. The Biomer and B-PEO4K grafts occluded within 1 month, while HEMA-st grafts were patent for over 3 months. Biomer and B-PEO4K showed thick multilayers of adsorbed proteins, and the thickness increased with implantation periods and the composition altered with time. In contrast, HEMA-st showed a monolayer-like adsorbed protein pattern, and the composition and thickness were consistent regardless of implantation time including in vitro short-time experiments, which may attribute to less conformational change of adsorbed proteins on HEMA-st surfaces. In terms of nonthrombogenicity, the stable monolayer-like adsorbed protein layer on HEMA-st surfaces exhibited improved blood compatibility over thick multilayered adsorbed proteins on Biomer and B-PEO4K surfaces.

Adsorption↗
PubMed1992

[Surgical treatment of ventricular tachycardia after total correction of tetralogy of Fallot].

A 38-year-old man with total repair of tetralogy of Fallot at the age of 16 suffered from paroxysmal ventricular tachycardia. His first attack of sustained ventricular tachycardia was recognized at the age of 37 and it was refractory for medical therapy. Electrophysiologic study demonstrated two morphological types of clinical ventricular tachycardias, one originated from the outflow tract of the right ventricle and the other from the area around the patch for closure of ventricular septal defect. He underwent cryosurgical ablation for ventricular tachycardia and patch-closure for residual shunt of ventricular septal defect following the failure of electrical ablation. All of clinical ventricular tachycardias disappeared postoperatively without antiarrhythmic drugs.

Adult↗
PubMed1992

[A clinical assessment of efficacy in continuous retrograde cerebral perfusion method].

From November 1990 to June 1991, 8 patients underwent surgical repair using continuous retrograde cerebral perfusion (CRCP). We evaluated the effect of CRCP from these 8 cases. As a method of CRCP, we perfused with oxygenated blood from SVC canulae with a internal jugular vein pressure of 30-40 cmH2O. Simultaneously systemic perfusion from femoral arterial canulae was performed. At nasopharyngeal temperature of 15-21 degrees C, CRCP time was 46-115 minute. SVC perfusion flow was 280-900 ml/min, and femoral arterial perfusion flow was 450-1,200 ml/min. At 30 minute after starting CRCP, oxygen tension of the blood which was returned to aortic arch was 11-23 mmHg, whereas oxygen tension of the SVC perfusion blood was 210-398 mmHg. In only one patient, transient involuntary movement was seen after operation, but prolonged emergence from anesthesia was not seen. In conclusion, CRCP is considered as an useful method in the operation of the aortic arch.

Aorta, Thoracic↗
PubMed1992

[Surgical repair of distal aortic arch aneurysm using "elephant trunk" technique].

We present a surgical case of 61-year-old man with distal aortic arch aneurysm. Under selective cerebral perfusion in deep hypothermia, we approached to the aneurysm through median sternotomy. Dilated distal aortic arch and proximal descending aorta with mural thrombus in the aneurysmal lumen were found. The aortic occlusion balloon catheter was inserted into the descending aorta. A Cooley woven Dacron graft (26 mm in diameter) was anastomosed at 5 cm above its distal end loosely to the descending aorta with five interrupted mattress sutures, and the distal portion of the graft was pushed down into the distal aorta ("elephant trunk" technique). Postoperative course was uneventful and the dead space around the graft in aneurysm was filled with thrombus. Six months later, however, emergent operation was performed because of compression of the bronchus and the esophagus by enlargement of the aneurysm due to leakage. The second operation was approached through 5th left intercostal thoracotomy and median sternotomy. The aneurysm was opened, and the thrombus was amounted to 500 g. The distal end of the graft was anastomosed end-to-end to the mid-portion of the descending thoracic aorta. Postoperative course was uneventful and the patient was discharged. It is concluded that Elephant trunk technique is effective and the postoperative control of hypertension is very important.

Aorta, Thoracic↗
PubMed1992

[A case report of thrombosed St. Jude Medical valve in a patient with macroglobulinemia].

A 66-year-old man who had undergone MVR using a ST. Jude Medical valve entered the hospital with acute heart failure and cardiogenic shock 3 months after surgery. He had had a symptom of petechiae due to macrogloburinemia after initial MVR and had been in the poor control of anticoagulation therapy because of presence of petechiae. He was diagnosed as prosthetic valve thrombosis using echocardiography and underwent emergency re-MVR using a Central Open Bioprosthesis (COB) which was developed by our department. He was doing well 8 month after re-MVR. Selection of prosthetic valve should be performed carefully in the patient with hemorrhagic disease, and careful observation and proper anticoagulant therapy should be carried out after valve replacement.

Aged↗
PubMed1992

[A rabbit model for evaluation of a small-caliber vascular graft].

A method for experimental study for a long small-caliber vascular graft was developed and used to observe the healing process and antithrombogenicity of a high porosity fabric prostheses. Eight rabbits weighing 3 kg were used. A left thoracotomy was performed. The thoracic descending aorta was clamped with two vascular clamps and excised in the middle without temporary shunt. A 15 cm long by 4.0 mm ID segment of a fabric prostheses (porosity: 3000) was implanted end to end. After the blood flow of the aorta was restarted, the graft remained in a big loop shape in the thoracic cavity. Total operating time was less than one hour. Three animals were lost because of bleeding from the anastomotic sites (2) and bleeding from the lung (1) within 12 hrs, but paraplegia was not produced. One animal died because of an occlusion in the graft at 16 days after implantation. The remaining 4 animals survived. In two out of these four animals, an angiography was performed. Two grafts were still patent at four weeks. One of these two was explanted and its smooth surface was observed. The major advantage of this technique is that we could evaluate a long small-caliber vascular graft in a small animal.

Animals↗
PubMed1992

[Classification of congenitally bicuspid aortic valve and its angiographic and surgical significance].

From January, 1978 to December, 1990, 85 patients with congenital bicuspid aortic valve underwent aortic valve replacements (AVR) with St. Jude Medical valve prosthesis. We classified congenital bicuspid aortic valve into four types. Type I (44.7%): Two cusps are situated right and left, a coronary artery arises from each related sinus of valsalva. Type II (22.4%): Type I + raphe in the right cusp. Type III (3.5%): one cusp is located anteriorly, the other posteriorly and both coronary arteries arise from anterior cusp. Type IV (29.4%): Type III + raphe in the anterior cusp. Regarding to preoperative diagnosis, aortic stenosis dominated in Type I (78.8%) and aortic regurgitation dominated in Type IV (72.0%). Implanted valve sizes were 22.2 +/- 1.8 (Type I), 23.4 +/- 1.6 (Type II) and 24.0 +/- 2.2 (Type IV). There was a significant difference between Type I and Type II, same as Type I and Type IV. Babb's method and outflow measurement method were utilized to predict the aortic annular size. However, both of them were not reliable for estimating the size of the aortic annulus in cases of aortic stenosis undergoing AVR with a 21 mm prosthesis.

Adolescent↗
PubMed1992

[A useful method for the surgical treatment of active infective endocarditis--a case report using the Teflon felt reinforcing method].

In the surgical treatment for active infective endocarditis (IE), perivalvular leakage is the most severe complication. We had a 42-year-old man who had active IE and a giant vegetation in the aortic valve, and a small mycotic aneurysm in the left ventricular outflow tract. Other operative observations included slight redness and a decrease in the reflex of the annular endocardium. We made a patch closure of the mycotic aneurysm, and aortic valve replacement using the Teflon felt reinforcing method. In the postoperative course, he had a pacemaker implantation with complete AV block. Postoperative pathological examination revealed inflammatory cells and plasma infiltration, and edematous change of the interstitial tissue around the cusp surface and annular side of the resected valve. These pathological changes could explain the redness and the decrease in the reflex of the annular endocardium. The edematous changes of the annular tissue might be the cause of postoperative perivalvular leakage. Reinforcement of the prosthetic valve with Teflon felt might be a useful method to prevent perivalvular leakage. There is, however, the possibility of acceleration or elongation of infective endocarditis. In our experiences of the surgical treatment for active IE, we performed valve replacement using Teflon felt in 6 patients, and not using in 27 patients. The mean period until CRP had been normalized was no significant difference between both groups (mean days using Teflon felt were 63.5 days, and not using were 75 days).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Rabbit model for evaluation of a long small-caliber vascular graft.

We developed an experimental method for evaluating the properties and healing process of a long, small-caliber vascular graft in a small animal. Eight rabbits were used. A left thoracotomy was performed and the thoracic aorta was isolated. The aorta was clamped and excised in the middle without a temporary shunt. A 15-cm-long by 4.0-mm-ID segment of a vascular graft was implanted end to end. After the blood flow of the aorta was restarted, the long graft remained in a big loop shape in the thoracic cavity and showed no tension. The major advantage of this technique is that, although it is simple, we are still able to evaluate a long, small-caliber vascular graft in a small animal.

Animals↗