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Biomedical subjects

M Tago

Publications and source records attributed to M Tago.

At least 73 records · Page 4Linked to original sources
PubMed1983

Simplified method of heterotopic cardiac transplantation for left ventricular assist.

A method of heterotopic cardiac transplantation has been developed which is performed through a left thoracotomy and requires only two vascular anastomoses. Systemic heparinization and cardiopulmonary bypass are not necessary. Preliminary experiments demonstrated that this heterotopic transplant technique was effective for left ventricular assist; in some experiments, a multimode atrioventricular programmable pacemaker was used to provide sequential pacing for "counterpulsation." This technique or similar techniques may have potential clinical benefit for patients with intractable left ventricular failure.

Animals↗
PubMed1983

Light and electron microscopic evaluation of canine hearts orthotopically transplanted after 24 hours of extracorporeal preservation.

The hearts of 19 dogs were subjected to in vitro, moderately hypothermic, whole blood perfusion through the aorta for 24 hours. Sixteen of the hearts were reimplanted into recipient animals in the conventional orthotopic fashion and three were subjected to histologic study without reimplantation. Fourteen of the 16 reimplanted hearts successfully supported the recipients. Histologic and ultrastructural studies of the reimplanted hearts 24 hours and 7 days after implantation demonstrated good preservation of cellular and ultracellular structures. Some mild widening of the interstitium was noted.

Animals↗
PubMed1983

Noninvasive radioisotopic technique for detection of platelet deposition on bovine pericardial mitral-valve prosthesis and in vitro quantification of visceral microembolism in dogs.

Platelet deposition on bovine pericardial-tissue mitral-valve prostheses in dogs was observed noninvasively by use of 111In-labeled platelets and quantified after sacrifice at one, 14 and 30 days postimplantation (300-400 microCi of labeled platelets having been injected 24 hrs previously). Thrombosis on the sewing ring and pericardial leaflets at one and 14 days and on the leaflets at 30 days was delineated in scintiphotos. In vitro quantification (% injected dose) indicated that the sewing ring and perivalvular tissue retained 0.75% of labeled platelets at one day postimplantation, 0.084% at 14 days, and 0.0042% at 30 days. Platelet survival was reduced to 38 hrs at 21 days postimplantation but returned toward the normal (50 hrs) with endothelial covering of the sewing ring. Microemboli in lung and kidney, as measured by tissue/blood radioactivity ratio, decreased significantly at 30 days. 111In-labeled platelets thus provide a sensitive marker for noninvasive imaging and in vitro quantification of platelet deposition on valvular prostheses and microemboli trapped in viscera.

Animals↗
PubMed1983

[Successful ex vivo preservation of canine hearts for 24 hours].

Prolonged storage of hearts in a viable condition is one of the most important problems of cardiac transplantation. Recently we have developed the new perfusion system and succeeded in preserving hearts extracorporeally for 24 hours in beating condition. In this series nine canine hearts were preserved for 24 hours by this perfusion method. Three of them were only for preservation and six were transplanted orthotopically into the recipient dogs after 24 hours preservation. These hearts were examined by light and electronmicroscopy at the different stages, namely after 24 hours preservation, at 24 hour after transplantation, on 7th day after transplantation. The morphological study demonstrated that myocardium showed no evidence of structural damage. This perfusion system is newly developed and one step to the clinical use for long-term heart preservation.

Animals↗
PubMed1980

Myocardial protection of only the left coronary artery perfusion in patients with isolated aortic valve replacement.

Effectiveness of only left coronary perfusion on myocardial protection was assessed by measuring serially cardiac functions such as cardiac index (CI), stroke index (SI), left ventricular minute work index (LVWI) and left ventricular stroke work index (LVSWI) in 22 consecutive patients with isolated, scheduled aortic valve replacement. The cardiac functions were determined 2,4 and 6 hours after open heart surgery. Correlation coefficients(r) between coronary perfusion time and the cardiac functions were less than 0.23, such being statistically insignificant. SI and LVSWI were in statistically significant inverse correlation to the preoperative NYHA classification and extracorporeal circulation(ECC) time for 4 hours following open heart surgery, and CI and LVWI for 2 hours. The correlation coefficients were highest at the 2nd postoperative hour and then decreased with passage of time. Therefore, the cardiac dysfunctions occurring in the postoperative period correlated either to the preoperative NYHA classification or ECC time, or both. It does, however, seem likely that the dysfunctions were correlated to ECC time as the recovery time of 4 hours from the dysfunction is too short for preoperatively existing dysfunction. Therefore, it was concluded that the continuous perfusion of only the left coronary artery was not the determinant factor of the postoperative dysfunctions and that the ECC time afforded detrimental effects, although such continued for 4 hours in terms of SI and LVSWI, and 2 hours in term of CI and LVWI.

Adult↗
PubMed1976

Experimental studies on the long term fate of the vein and artery grafts and its choice in aortocoronary bypass surgery.

Experimental studies of aorto-coronary bypass were performed using the technique of distal coronary artery perfusion in 47 dogs to ellucidate the flow characteristics at various grafts and long term fate of grafts up to 440 days after operation. On short term results, early graft occlusion seems to occur within 2 weeks with 6.5 days of mean in Group I and II (free grafts) when inflammatory reaction is most prominent. After 2 weeks patency rate was 65% in Group I and II, more than 80% of patency rate were obtained in Group III. In Group IV (prosthetic grafts), all but few (3 cases) could survive for more than 24 hours. In flow characteristic, artery and vein graft of which diameter is larger than that of the coronary artery can maintain enough the basal flow after ligation of the proximal coronary artery. In Group III (IMA-Circumflex anastomosis group), the internal mammary artery must be large enough to carry the blood to coronary artery lest the graft flow becomes below the basal flow. In Group IV, grafts can carry full flow but long term studies were not done because of early graft occlusion. There are much differences between free artery and vein grafts. In artery graft except IMA proper arterial structure is being kept until 440 days but has arteriosclerotic wall changes similar to human being. On the contrary, almost all free vein grafts have subintimal hyperplasia with collagen deposit and fibrous tissue and still progress after one year. These findings demonstrate that ischemia and hydrauiic effect in the graft must be important factor for the irreversible graft wall changes.

Animals↗
PubMed1975

Prediction of prognosis in open-heart-surgery by regional difference in leg surface temperature.

Change of the surface temperature of the leg during open-heart-surgery was determined in five patients, in whom either side of the femoral artery was ligated for cannulation. While the surface temperature at the patella was least influenced, that at the ankle paralleled closely the changes in the core body temperature and blood supply to the leg. Their difference (P-A difference) was studied to see if they can be used to predict prognosis of patients undergoing open-heart surgery. The P-A difference was followed for several hours after the open-heart surgery. It was marked positive when the surface temperature at the patella was higher than that at the ankle. Total of 54 patients were studied. Only one out of 29 patients with negative P-A difference succumbed. This is in sharp contrast to the 25 remaining patients with positive P-A difference, from whom as many as 12 died. In addition, the postoperative course of the 13 survivors from the latter group was more eventful. Since P-A difference seemed to indicate accurately cardiac output by reflecting the state of the peripheral circulation, it can be used as a useful parameter in prediction of the prognosis in open-heart surgery.

Adolescent↗
PubMed1975

[The accessory middle cerebral artery (author's transl)].

The accessory middle cerebral artery has rarely been documented. Four cases of the anomalous artery were found in 1240 carotid angiograms, the incidence being estimated to be 0.24 to 0.34%. Ages of the patients were 45, 52, 53, and 56. They were two males and two females. In two patients, the angiography was carried out because of positive neurological signs after head injury, and in the other two, because of cerebrovascular stroke. All the anomalous arteries were found as incidental findings. The angiography was carried out bilaterally in two patients and the anomalous arteries were found only on one side. They arose from the horizontal portion of the anterior cerebral artery and coursed laterally in paralled with the stem of the middle cerebral artery. Two of them gave rise to the perforating arteries into the brain which accompanied those from the middle cerebral artery. These atomalous arteries were identified very easily on an antero-posterior projection of the angiogram. In the most striking patient, the 52-year-old man, a selective angiography for the middle cerebral artery, which did not demonstrate the anterior cerebral artery and its branch, the accessory middle cerebral artery, was carried out and in the light of the findings, the accessory middle cerebral artery could be identified running in elliptic circle just above D1 on the lateral projection of the routine carotid angiogram. All the accessory middle cerebral arteries in our series were not associated with either intracranial aneurysm or anomalies such as agenesis of the corpus callosum and reduplication of the circle of Willis.

Cerebral Angiography↗
PubMedDate not supplied

Radioisotopic techniques for noninvasive detection of platelet deposition in bovine-tissue mitral-valve prostheses and in vitro quantification of visceral microembolism in dogs.

Platelet deposition on bovine pericardial-tissue mitral-valve prostheses in 11 dogs was observed noninvasively by use of 111In-labeled platelets and quantified after sacrifice at one (n = 3), 14 (n = 3), and 30 (n = 5) days postimplantation (300-400 microCi of labeled platelets having been injected 24 hours previously). Thrombosis on the sewing ring and pericardial leaflets at one and 14 days and on the leaflets at 30 days was delineated in scintiphotos. In vitro quantification (% injected dose) indicated that the leaflets, sewing ring, and perivalvular tissue retained 0.904% of labeled platelets at one day postimplantation, 0.198% at 14 days, and 0.040% at 30 days. Platelet half-life was reduced to 38 hours at 21 days postimplantation but returned toward the normal (50 hours) with fibrous ingrowth in the sewing ring. Microembolism in lung and kidney, as measured by tissue/blood radioactivity ratio, also was decreased significantly at 30 days. 111In-labeled platelets thus provide a sensitive marker for noninvasive imaging and in vitro quantification of platelet deposition on valvular prostheses and microemboli trapped in viscera, although histochemical confirmation will be necessary to correlate the increase in tissue/blood ratio with the presence of microembolism.

Animals↗