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Biomedical subjects

M Kawasuji

Publications and source records attributed to M Kawasuji.

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

Development of a new intraoperative radiofrequency ablation technique using a needle electrode.

We studied a new intraoperative technique for radiofrequency ablation using a needle electrode. The ventricles of 12 mongrel dogs were ablated. The needle electrode was inserted to a depth of 3 mm through the epicardium. Macroscopically, tissue defect was found only at the needle insertion site. The degenerated area had a well-demarcated bullet shape with microscopical coagulation necrosis. This characteristic shape allows the ablation of deeper areas of the myocardium by deeper insertion of the ablation needle. Compared with conventional epicardial surface ablation, this new method could be used to achieve deeper coagulation. For any given energy level and conductance, the ratio between the volume and the depth of the lesion with this new method is smaller than that of lesions made by the conventional radiofrequency ablation method. With this new method, the energy spreads vertically, a characteristic suitable for deep ablation. This may result from the shape of the needle electrode itself. For ablation of deep targets, this new method is superior to the conventional approach because less myocardium is coagulated and the target can be ablated with greater efficiency, requiring the destruction of less tissue. In conclusion, the needle electrode procedure can achieve a narrower ablation for deeper targets than can the conventional technique.

Animals↗
PubMed1994

Myocardial coagulation by intraoperative Nd:YAG laser ablation and its dependence on blood perfusion.

To investigate whether the efficacy of intraoperative laser ablation therapy is affected by myocardial blood perfusion, we irradiated 11 canine hearts through the epicardium with a Nd:YAG laser (10, 20, and 30 J/mm2) using air as the medium. Compared coagulated myocardial depth, width, and volume obtained in the red beating heart was compared with those in the white nonbeating heart infused with 0 degrees C saline (cardioplegic model) via the coronary artery. Histologically, the macro- and microscopical findings were very similar. At each level of energy, the width and volume of red myocardium coagulated were significantly larger than those of white myocardium (P < 0.01). At 30 J/mm2, the depth of coagulation of red myocardium was significantly larger than that of white myocardium (P < 0.01). The coagulated volume of the white myocardium was about 60% of that of the red myocardium. Nd:YAG laser energy was absorbed by blood (red color = hemoglobin), and more energy was transferred in the higher temperature myocardium. During intraoperative Nd:YAG laser ablation, the presence of blood perfusion in cardiac tissue is thought to be an important factor affecting safe irradiation.

Animals↗
PubMed1994

The effects on blood flows of coronary artery by-pass grafts during intra-aortic balloon pumping.

The internal thoracic artery (ITA), as well as aorto-coronary by-pass grafts, has been used for widely coronary artery by-pass grafting. Intra-aortic balloon pumping (IABP) is the first choice for left ventricular support when low output syndrome occurs during coronary artery by-pass surgery. However, the effect of diastolic augmentation by IABP may vary to the type of grafts. Graft flow with and without IABP support were measured in six patients undergoing elective coronary artery bypass surgery requiring IABP at Kanazawa National Hospital. The patients ranged in age from 59 to 67 years, with a mean age of 63 years, and included one woman and five men. In all cases, the left ITA was dissected from the thoracic wall as pedicle, and anastomosed in situ to the left anterior descending artery. Saphenous vein grafts (SVGs) were used for aortocoronary by-pass to the obtuse marginal branches, the first diagonal branches, the left circumflex branches, and/or the right coronary artery. Blood flow in 6 ITAs, 11 SVGs to the left coronary artery systems, and three SVGs to the right coronary artery was measured by ultrasound transit-time flowmeter simultaneously with the electrocardiogram. Blood flows in ITA grafts and SVGs were measured during IABP assist and unassisting under hemodynamically stable conditions after discontinuing cardiopulmonary by-pass. The systolic and diastolic flows of each graft were measured using the peak of the R wave and the end of T wave on the electrocardiogram as the references for systole. Systolic flow during IABP were similar to unassisted flow in both ITA and SVGs.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

[Quantitative hemodynamic assessment of internal thoracic artery grafts using transthoracic duplex imaging].

The hemodynamics of blood flow in internal thoracic artery (ITA) grafts were studied using transthoracic duplex imaging prior to and following coronary artery bypass grafting (CABG) in 37 patients. Transthoracic images of the ITA were obtained through the first intercostal space using a 7.5 MHz probe, and their diameter and area were measured by B-mode imaging. Systolic, diastolic, mean and end-diastolic blood flow velocity (Vs, Vd, Vm, and Ved) were determined based on Doppler signals and systolic, diastolic, and total blood flow (Fs, Fd, and Ftotal) were calculated by the following formula: Flow = Vm x area x 60/10(3). The diameter of the ITA increased following CABG. Prior to CABG, Vs, and Fs, were dominant, while following CABG, the hemodynamic pattern was diastolic dominant, although individual variation existed. The ITA blood flow was measured in 4 groups, in patients who had had a previous anterior myocardial infarction and no redistribution on myocardial scintigraphy (group I), in patients with 99-100% coronary artery stenosis who had not had an anterior myocardial infarction or who had an anterior myocardial infarction and had redistribution (group IIa), in patients with the same criteria as group IIa but who had 90% coronary stenosis (group IIb), and in patients with 75% coronary stenosis who had not had anterior myocardial infarction (group IIc). Blood flow was 57, 73, 44mL and 34 mL/min, and the percentage of diastolic flow was 72, 69, 61, 59% respectively. These results show that ITA blood flow competes with native coronary artery flow in patients with moderate coronary stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Immediate haemodialysis and staged fasciotomy in the treatment of reperfusion injury.

A 67-year-old man was admitted with traumatic arterial occlusion in his leg 24 h after an accident. A double-lumen catheter was inserted into the left iliac vein, after revascularization, and haemodialysis started using a new membrane dialyser to remove myoglobin effectively. Intramuscular pressure of the limb was measured and, when it was 35 mmHg, staged fasciotomy was performed. A modification of the procedure used to prevent myonephropathic metabolic syndrome and compartment syndrome is described.

Aged↗
PubMed1993

Effect of low-dose aprotinin on coagulation and fibrinolysis in cardiopulmonary bypass.

To study the effect of low-dose aprotinin on hemostasis in patients undergoing cardiopulmonary bypass (CPB) for coronary artery bypass operations and to elucidate the mechanism of aprotinin action, we randomized 14 of 27 patients to receive 30,000 KIU/kg aprotinin in the CPB priming volume and 7,500 KIU/kg aprotinin intravenously each hour during CPB (1 patient was excluded from the aprotinin group because of protamine shock). Intraoperative and postoperative blood loss was significantly reduced in the aprotinin group. Antithrombin III level was significantly decreased, and the levels of thrombin-antithrombin III complexes were significantly increased during CPB in both groups, indicating activation of the clotting system. The marked increase in fibrin(ogen) degradation products during CPB in the control group, indicating enhanced fibrinolytic activity, was significantly reduced in the aprotinin group. alpha 2-Plasmin inhibitor was significantly reduced during CPB in the control group. The marked increase in alpha 2-plasmin inhibitor-plasmin complexes in the control group, indicating plasmin activity, was significantly reduced in the aprotinin group. A marked decrease in the platelet count was observed during CPB similarly in both groups. These findings demonstrated that low-dose aprotinin administration was effective in reducing intraoperative and postoperative blood loss and that activation of the clotting system during CPB was not followed by hyperfibrinolysis in aprotinin-treated patients. The improved hemostasis is mainly attributable to the prevention of hyperfibrinolysis during CPB.

Antifibrinolytic Agents↗
PubMed1993

Physiologic characteristics of coronary artery bypass grafts.

To investigate the hemodynamic characteristics of arterial grafts for coronary artery bypass grafting, we measured phasic pressure and flow patterns in three types of grafts in a canine model (n = 18). A graft from the ascending aorta (AAG), a graft from the descending aorta at the first lumbar level (DAG), analogous to a right gastroepiploic artery, and an internal thoracic artery (ITA) were anastomosed to each other. The composite graft was anastomosed to the left anterior descending coronary artery, and then the left anterior descending coronary artery was ligated. Before grafting, the AAG showed high sustained diastolic pressure, but the ITA and DAG showed rapid fall of diastolic pressures. Mean diastolic pressures were 83 +/- 2, 72 +/- 3, and 57 +/- 2 mm Hg in the AAG, ITA, and DAG (p < 0.05). Free flow in the AAG was markedly greater than in the ITA or the DAG. After grafting to the left anterior descending coronary artery, no changes were observed in diastolic pressures compared with the pregrafting values. Total blood flows were 72 +/- 6, 80 +/- 7, 57 +/- 7, and 44 +/- 6 mL/min in the left anterior descending coronary artery, AAG, ITA, and DAG, respectively. There were no differences in systolic graft flow between the three types of grafts. Diastolic blood flow in the ITA (29 +/- 4 mL/min) and DAG (18 +/- 3 mL/min) was smaller than in the AAG (48 +/- 4 mL/min) (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Flow capacities of arterial grafts for coronary artery bypass grafting.

The flow capacities of arterial and saphenous vein grafts in 100 patients who had coronary artery bypass grafting were compared under exercise conditions by continuous ventricular function monitoring, which records serial beat-to-beat radionuclide data and calculates left ventricular ejection fractions every 20 seconds. Ejection fraction profiles during graded bicycle exercise were divided into four types. In type A, the ejection fraction continued to increase. In type B, the ejection fraction initially increased, but decreased during the late exercise stage. In type C, the ejection fraction did not change. In type D, the ejection fraction continued to decrease throughout exercise. A decrease in ejection fraction, observed in type B or D, is an early indicator of myocardial ischemia. Before operation, 10 patients showed type A, 30 type B, 11 type C, and 49 type D responses. After operation, 68 patients showed type A, 21 type B, and 11 type C responses. Patients were divided into three groups according the type of bypass graft. Group 1 included 21 patients with two arterial grafts and vein grafts; group 2, 61 patients with an internal thoracic artery graft and vein grafts; group 3, 18 patients with only vein grafts. All of the grafts were patent on angiography. Eight patients (38%) in group 1 and 13 (21%) in group 2 showed a postoperative type B response, but none of the patients in group 3 had a postoperative type B response (p < 0.02). Seven of 8 patients in group 1 with postoperative type B responses had only arterial grafts to the left-side coronary arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Effect of aprotinin on blood loss reduction after extracorporeal circulation].

High-dose aprotinin has been reported to reduce blood loss after extracorporeal circulation (ECC). However, the hemostatic mechanism of aprotinin remains unknown. We administered aprotinin to 25 patients during coronary artery bypass surgery and examined the blood loss in comparison with that in a control group of 25 patients. On the basis of an experimental study on the effects of aprotinin, 30,000 KIU/kg of aprotinin was infused as the initial ECC dose and 7,500 KIU/kg/h was continuously administered as the maintenance dose from the beginning to the end of ECC. Aprotinin was not used before ECC. Serial blood samples were collected during and after the operation in both groups to examine various coagulation and fibrinolysis system parameters. Blood loss during and 6 hours after the operation and the total blood requirement were significantly lower in the aprotinin group than in the control. There was no difference between the two groups in terms of hemoglobin, platelet count, ACT, and thrombin-antithrombin III complex level. The aprotinin group showed a significantly higher level of alpha 2 (total) plasmin inhibitor and a significantly lower level of plasmin-alpha 2 plasmin inhibitor complex and D-dimer during ECC. These findings indicated that although the coagulation system function was accelerated during ECC, the fibrinolysis function system was suppressed by the administration of aprotinin, which resulted in a reduction of blood loss.

Adult↗
PubMed1993

[A case of treating abrupt closure due to post PTCA dissection by emergent CABG-reoperation, via extracorporeal circulatory method conducted with the heart "beating"].

A female patient, 73 years of age, who underwent CABG for the RCA and First Diagonal Branch by SVG 39 months ago was readmitted to our clinic after an onset of acute angina pain, whereupon successful PTCA was performed to Cx segment 13. However, with the angina pain continuing unabated, and with the recognition through emergent CAG that the graft to the RCA was occluded. PTCA was performed again to the RCA segment 1. The segment was closed off by dissection. The emergent CABG was carried out via femoro-femoral extracorporeal circulation and intra aortic balloon pumping. This CABG was of a RCA to RCA bypass nature, with SVG performed with the heart "beating" and without cooling. The patient was thus relieved of her angina pain and her cardiac function has since been in good order.

Aged↗
PubMed1993

[A case of left ventricular aneurysm associated with acromegaly].

We performed a left ventricular aneurysmectomy for a left ventricular aneurysm associated with acromegaly in a 62-year-old man. Bromocriptine mesilate was administered to suppress high growth hormone (GH) levels, and there were no complications during or after the operation. The majority of patients with acromegaly die of cardiovascular diseases such as cardiomegaly, hypertension, arteriosclerosis of the coronary arteries, congestive heart failure, valvular disease, and arrhythmia. Ventricular aneurysm is a rare complication of acromegaly. In order to safely operate, it is important to control serum GH levels and pay special attention to the well-known complications of acromegaly such as diabetes mellitus and hypertension.

Acromegaly↗
PubMed1993

[Strategy for cerebral protection during aortic arch replacement].

We analyzed cerebral protection of twenty-five patients, 11 of whom underwent ascending-arch aortic replacement and 14 underwent aortic arch replacement, supported with cardiopulmonary bypass. Twenty of patients underwent selective cerebral perfusion (SCP) with moderate hypothermic circulatory support; 12 of single SCP, 8 of double SCPs. Major arch branch reconstruction were performed with 11 patients; 3 of triple branches, 2 of double branches and 6 of single branch reconstruction. Cerebral impairment was found in 7 patients (25%) with SCP; 3 of them died of low output syndrome and major bleeding during perioperative period. Four of 17 patients, who survived more than one month, showed cerebral infarction in 2 patients and temporary neurological deficit in 2 patients. Our strategies for cerebral protection are (1) careful cerebral four vessels study, (2) SCP with perfusion pressure more than 40 mmHg and flow rate of 7-10 ml/kg/min under moderate hypothermia, (3) bilaterally double branches perfusion minimally for arch replacement, (4) intensive cerebral monitoring from multiple aspect, (5) pharmacological support with barbiturate or aprotinin, (6) gentle maneuver and reliable major branch cannulation to prevent debris embolism.

Aortic Dissection↗
PubMed1993

[Successful aorto-circumflex coronary bypass grafting through left thoracotomy following aortic and mitral valve replacement].

We report successful descending thoracic aorto-circumflex coronary artery bypass grafting using a saphenous vein graft through left thoracotomy in a 44-year-old female. The patient developed severe angina attack after aortic and mitral valve replacement. Coronary angiography showed 99% stenosis of the circumflex coronary artery. Under general anesthesia, left femoral vein to arterial partial cardiopulmonary bypass was performed via left 4 th intercostal space. Body temperature was lowered to 22 degrees centigrade, and spontaneous cardiac fibrillation occurred. After minimal exposure by pericardial dissection of the circumflex coronary artery, distal anastomosis and then proximal anastomosis at the descending thoracic aorta was carried out under cardiac fibrillation. This surgery was done with minimal intra-and postoperative bleeding. Postoperative course was very smooth, and the patient was discharged and leading a normal life for 6 months after surgery.

Adult↗
PubMed1993

[The value of omental pedicle flap method for postoperative intractable infection in the field of thoracic surgery].

We present a series of 8 consecutive patients who underwent the omental pedicle flap method in the field of thoracic surgery. Four of them had empyema with bronchopleural fistula and four had mediastinal infection. A pedicle of omentum containing the right gastroepiploic artery was passed through a tunnel in the diaphragm into the empyema cavity or the mediastinal abscess cavity. All eight patients were cured successfully by single-stage procedures. We think this series demonstrates the value of omental pedicle flap method which lacks in symptoms due to defected organ and offers an excellent therapeutic effect with easy operative procedure. And, this method produce a quality of life. Further active application of this method can be expected in the management of chest problems.

Adolescent↗
PubMed1992

[Physiological characteristics of arterial graft for coronary artery bypass surgery].

Arterial grafts have been used widely for coronary artery bypass grafting (CABG) because of their excellent long patency. However, some clinical reports suggest that blood flow in arterial grafts may not be adequate compared with aorto-coronary bypass grafting. Pressure in arterial grafts was measured in patients undergoing CABG. The pressure tracing in the ascending aorta (AA) was maintained during diastole. The systolic pressure wave in ITA and GEA was narrow, while the diastolic pressures fell rapidly: the diastolic pressure in GEA was lower than in ITA. The area under the pressure wave was measured in diastole and in systole. Although there was no significant difference in systolic areas, the diastolic area were lower in ITA than in AA, and lower in GEA than in AA and in ITA. These results clarified that arterial grafts which belong to the systolic-dominant systemic circulation have disadvantages over aorto-coronary bypass grafts, in terms of physiological suitabilities to the diastolic-dominant coronary circulation.

Adult↗
PubMed1992

[Right coronary spasm immediately after coronary artery bypass grafting for the left coronary artery].

Right coronary spasm immediately after coronary artery bypass grafting for the left coronary artery in a 39-year-old male is described. After the patient was returned to ICU, ECG at leads II, III, and aVF changed suddenly, ventricular tachycardia (right ventricle origin) and cardiac arrest ensured. As neither administration of drug nor application of D.C. was effective. The chest was reopened at ICU. Though there was sufficient flow in the left coronary artery bypass graft flow, the right ventricle did not constrict at all. Right coronary artery spasm was diagnosed, and, upon application of the direct cardiac massage and D.C. at the cardiac surface, cardiac rhythm and blood pressure were normalized. IABP was inserted to improve cardiac function, and the chest was closed. In addition, nitroglycerin and diltiazem were infused continuously. No spasm has occurred after this episode, and the patient has been discharged and is doing well.

Adult↗
PubMed1992

[Coronary artery bypass surgery in a patient with hypopituitarism].

Patients with hypopituitarism are prone to perioperative complications resulting from adrenal insufficiency or hypothyroidism. Coronary artery bypass grafting was performed safely in a 53-year-old woman with postinfarction unstable angina and hypopituitarism. Cortisol and thyroid hormone were administered to maintain normal adrenal and thyroid function during and after the operation. Hydrocortisone was administered intravenously the day before surgery and for 2 weeks postoperatively and then was administered orally. Perioperative replacement thyroxine therapy was administered to avoid acute myocardial ischemia. Optimal thyroid replacement was achieved after surgery. No perioperative complications were seen. The patient remains free of angina with postoperative cortisol and thyroid hormone replacement therapy.

Angina, Unstable↗