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Biomedical subjects

T Jikuya

Publications and source records attributed to T Jikuya.

At least 55 records · Page 3Linked to original sources
PubMed1995

Acute effects of exercise on muscle MRI in peripheral arterial occlusive disease.

The midcalf muscles of eight patients who had peripheral arterial occlusive disease were evaluated by exercise MRI before and after bypass surgery or percutaneous transluminal angioplasty. MRI showed a high intensity of these muscles, especially the posterior muscles, after exercise in all patients before intervention. The mean T2 relaxation time was maximal immediately after exercise (tibialis anterior, T2 = 30.8 ms; soleus, T2 = 36.2 ms; gastrocnemius, T2 = 32.8 ms) and then gradually decreased to the preexercise level. The difference in the T2 relaxation time of the soleus between immediately after exercise and at rest was smaller along with improvement of ankle pressure indices (API) after successful intervention (mean T2 difference: 4.91 and 0.72 ms (p < .001); mean API: 0.54 and 0.86 (p < .001) before and after intervention, respectively). The mean resting midcalf T2 relaxation time was significantly higher after intervention (tibialis anterior, T2 = 28.4 and 29.5 ms (p < .05); soleus, T2 = 31.4 and 32.9 ms (p < .05); gastrocnemius, T2 = 29.5 and 31.1 ms (p < .01) before and after intervention, respectively). T2 relaxation time may be a useful quantitative parameter in peripheral arterial occlusive disease as well as in other muscle studies.

Aged↗
PubMed1995

Design of a centrifugal blood pump with magnetic suspension.

A new concept blood pump, whose impeller is suspended by permanent magnets and a mechanical pivot without seals or ball bearings, is presented in this paper. The primary aim of the blood pump is an application to implantable artificial hearts. The prototype model is of a centrifugal type with a four-vaned semiopen impeller 50 mm in diameter. Since this mechanism has no seals or ball bearings, flow stagnation or heat generation that might cause blood cell denaturation is expected to be small. The results of performance testing for the prototype model 2 were satisfactory regarding pump head and efficiency. The radial-suspension magnets and the magnetic coupling were stable. As a result, the present mechanism has been verified to be a candidate applicable to implantable artificial hearts.

Biomechanical Phenomena↗
PubMed1995

[Citrate and ionized calcium on extracorporeal circulation in pediatric cardiac surgery].

The control of optimum concentrations of ionized calcium Ca2+ during cardiopulmonary bypass is important in maintaining cardiac function and reducing reperfusion injury. Ca2+ may be in part dependent upon the serum level of citrate Cit in use of hemodiluted prime in pediatric cardiac surgery. The purpose of this study was to ascertain fluctuations of Ca2+ during bypass in relation to Cit and to study control of optimum Ca2+. Ca2+ and Cit was measured prior to and every 10 or 20 minutes during bypass in 12 children aged 21 days to 6 years. Of 6 patients (body weight less than 6 kg) received acid-citrate-dextrose (ACD) solution 20 ml before aortic declamp to give low Ca2+ for reducing reperfusion injury. Ca2+ showed initial drop and then gradually increased as the result of decreasing Cit. Ca2+ was inversely correlated with Cit (r = 0.85, p = 0.0001). When ACD 20 ml was added, Ca2+ significantly decreased from 1.00 +/- 0.13 to 0.65 +/- 0.13 mmol/l. However, Cit remained 24.3 +/- 13.3 mg/dl at the end of bypass. In conclusion, the results of this study suggest that gradually increasing Ca2+ during bypass may be related to the rate of citrate metabolism and the use of citrate for the control of Ca2+ remains questionable.

Calcium↗
PubMed1995

[A percutaneously controllable pulmonary artery banding device: clinical application].

An optimal pulmonary artery banding is often difficult with a conventional banding technique. It often requires readjustment after closing the chest. So we developed a percutaneously controllable pulmonary artery banding device and applied it in three patients. This device consists of silicone balloon being pasted on a reinforced silastic plate and silicone reservoir. The balloon is applied around the pulmonary artery and the reservoir is implanted subcutaneously. The control of the banding is accomplished percutaneously through the reservoir using a needle with fluid-filled syringe. This device worked successfully in two patients for percutaneous readjustment of pulmonary constriction and congestive heart failure was decreased. This device may offer proper constriction of the pulmonary artery without any surgical procedures after banding and may reduce surgical morbidity and mortality of sick children.

Animals↗
PubMed1995

[Postoperative bronchial stenosis associated with IAA complex and transendoscopic resection of intrabronchial granulation].

Problem with stenosis of the left bronchus was encountered in a patient with type B interrupted aortic arch complex after the arch reconstruction and pulmonary artery banding. Bronchoscopic study disclosed the intraluminal granulation of left bronchus and transendoscopic resection of the granulation successfully relieved the stenosis and brought the patient to full recovery.

Airway Obstruction↗
PubMed1995

[Application of large curved forceps for taping in cardiovascular surgery].

A new large curved forceps was manufactured for trial with the object of taping in cardiovascular surgery. Widely used and commercially available forceps could be utilized on the taping of large vessel less than 5 to 5.8 cm in diameter. With this new forceps, aneurysmally dilate great vessels (less than 8 cm in diameter) could be safely taped without compression of aortic wall. This forceps has already applied not only for the major vascular surgery, but also for the wearing of cardiac net in coronary artery bypass grafting.

Aortic Aneurysm↗
PubMed1994

The treatment of intractable supraventricular tachycardia after open heart surgery by a continuous infusion of verapamil and ventricular pacing.

Four patients who developed intractable supraventricular tachycardia (SVT) after open heart surgery were treated using a new therapeutic method of creating a pharmacological atrioventricular block by the continuous infusion of verapamil with ventricular pacing. Both the initial dose and the effective dose, being the verapamil dose necessary to maintain pharmacological atrioventricular block to prevent the recurrence of SVT, were surveyed with clinical results. The verapamil-induced hemodynamic changes observed 4 h and 8 h after treatment, as indicated by systolic arterial blood pressure, mean arteral blood pressure, heart rate, cardiac index, and urine volume, were compared with the values 1 h before treatment. After an initial low dose infusion of 0.07 +/- 0.02 mg/kg.h had been given, an effective and safe dose of 0.11 +/- 0.05 mg/kg.h was determined. Good hemodynamic and clinical results were achieved in all four patients who are now leading an active life. These results therefore encourage us to apply this therapeutic method for treating patients with intractable and recurrent SVT after open heart surgery.

Adult↗
PubMed1994

Internal hydraulic loss in a seal-less centrifugal Gyro pump.

A new index "loss factor Z" defined by Eq. 1 was introduced as the absolute expression of the mock loop resistance for testing a nonpulsatile pump. [formula: see text] where gamma is specific gravity of the fluid, g is the acceleration of gravity, delta P is total pressure head, and Q is flow. Z is expected to be constant, regardless of the pumping parameters. Z values obtained in the same mock loop but with different rotary blood pumps were almost identical and were defined as Z0. New methods of analysis of the flow-restrictive conditions of various rotary blood pumps are proposed in this paper: namely, differential loss factor delta Z, and loss factor sensitivity delta Z/delta A. The proposed Z-Q curves demonstrated better performance mapping than the conventional delta P-Q curves. Delta Z is the difference between the Z-Q curves of two different pumps. A is a design parameter of the pump; therefore delta Z/delta A is a quantitative expression of the effect of the design change on the hydraulic performance. These various indices were used to analyze the internal hydraulic loss of a centrifugal pump (Gyro pump). The relationship between its gap size (rotor casing) and hydraulic performance was assessed quantitatively by these indices. In this paper, the derivation processes and above-mentioned indices are described.

Assisted Circulation↗
PubMed1994

[Penetrating atherosclerotic ulcer of the iliac artery combined with abdominal aortic aneurysm--a case report].

A 76-year-old woman with abdominal aortic aneurysm was referred to our hospital with a complaint of abdominal pulsatile mass. CT and angiogram revealed infrarenal abdominal aortic aneurysm (AAA) with right common iliac aneurysm. AAA was replaced with the bifurcated Dacron graft and iliac aneurysm was resected concomitantly. A focal perforation of intima and medial wall hematoma were found in the iliac aneurysm. These findings corresponded with penetrating atherosclerotic ulcer (PAU). PAU in the abdominal aorta may form the abdominal aortic false aneurysm, and may cause the rupture of aneurysm. It is an critical sign of "aortic catastrophe".

Aged↗
PubMed1994

[Thrombolytic therapy of thrombosed Björk-Shiley aortic valve prosthesis--report of four cases].

Prosthetic valve thrombosis is associated with high mortality. Thrombolytic therapy is a promising alternative to valve replacement in the management of prosthetic valve thrombosis. To determine the efficacy and safety of thrombolytic therapy for thrombosed Björk-Shiley aortic valve prosthesis, 4 patients who received urokinase intravenously for this disorder were analyzed. In 3 patients, the successful outcome was sustained in that they remained asymptomatic and did not require operative intervention during follow-up, which ranged from 17 to 101 months. In one patient clinical signs of mild congestive heart failure occurred. This patient was surgically treated by thrombectomy and debridement of the prosthetic valve. Failure of urokinase treatment to resolve the thrombus after 1 week indicates that tissue overgrowth or fibrous, organized thrombus is the cause of prosthetic malfunction. Surgical intervention for this problem should be considered only after thrombolytic therapy has been tried and has failed. Our experience with urokinase treatment of thrombosis of aortic Björk-shiley prostheses indicates that this form of treatment should always be applied before surgical intervention. We also attempted to define the optimum protocol of fibrinolytic therapy by clinical evaluation. A protocol for the safe treatment of thrombosed valve is urokinase in initially administered in the doses as 960,000 units for 24 hours, then followed by a maintenance infusion at the half dose every 24 or 48 hours later. Thrombolytic therapy should be continued for 1 week at least to prevent rethrombosis even normalization of valve function was documented clinically. Simultaneous heparin infusion of 10,000 units for 24 hours is then started to replaced by warfarin treatment adjusted to obtain optimal prothrombin times.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Early repair of postinfarction ventricular septal perforation: a case report of an improved surgical technique].

Accurate repair of postinfarction ventricular septal perforation (VSP) has mainly depended on the technique for friable septal reinforcement. Modified closure of VSP with Xenomedica patch was performed in 63-year-old male. Friable border of the septum was successfully sandwiched between horse-shoe shape prejett (right side) and main patch (left side). The advantages of this modified surgical procedure are as follows: (1) septum can be seen through horse-shoe shape patch (even when tying the mattress sutures; (2) Xenomedica patch is flexible enough for avoiding the cutting for friable septum, and is strong enough for sandwiching the septum.

Heart Rupture, Post-Infarction↗
PubMed1994

[A case of coronary artery bypass grafting (CABG) in which root mean square total (RMST) improved markedly after redo-distal anastomosis].

A 59-year-old man underwent CABG with left internal thoracic artery (LITA) to the first diagonal branch and saphenous vein graft (SVG) to the right coronary artery (RCA). Pump off was quite uneventful, but re-anastomosis was done because bypass graft flow measured before the closure of chest was 6 ml/min, which was most likely due to sclerotic right coronary artery and technical error. After re-anastomosis, bypass flow of SVG to RCA was measured 95 ml/min. Root mean square total (RMST) immediately after aortic declamp for the first time was 39% compared with that measured prior to operation, but improved to 49% after aortic declamp at the second time. It recovered to 127% 2 days after operation, and 137% at 7th postoperative day. RMST indicates the total electropotential per unit time from the beginning to the end of QRS. It has the specificity to predict VT and postoperative pump failure. In this case, it is suspected that RMST may be a predictor that revascularization would be complete or incomplete in operations for ischemic heart disease.

Anastomosis, Surgical↗
PubMed1994

[Influence of ionized calcium concentration during cardiopulmonary bypass on pediatric cardiac surgery].

Changes of serum ionized calcium concentration (Ca2+) during cardiopulmonary bypass (CPB) were analyzed in 30 pediatric cardiac patients less than 15 kg body weight. Ca2+ decreased suddenly after the start of CPB, and it gradually increased to the normal value. Citrate added to the stored blood for priming and its metabolism might play a role in these changes of Ca2+. Addition of adequate volume of calcium chloride to the priming prevented sudden decrease of Ca2+. Although addition of citrate before aortic declamp effectively decreased Ca2+ and may prevent reperfusion cardiac injury associated with hypercalcemia, there were no correlation between predeclamp level of Ca2+ and serum CPK and GOT levels.

Body Weight↗
PubMed1994

[Two cases of coronary artery bypass grafting using great saphenous vein grafts in reversed Y-shaped for the atherosclerotic ascending aorta].

Coronary artery bypass grafting (CABG) was performed using saphenous vein grafts anastomosed in reversed Y-shaped in two patients because of the atherosclerotic ascending aorta. Postoperative course was uneventful, however, the common part of reversed Y-shaped grafts was occluded in both patients within two years after operations. The arms of reversed Y-shaped grafts were patent, and played a role of major collateral between LAD and RCA. They were treated successfully with reoperation in one patient and PTCA in another.

Aged↗
PubMed1993

Extra-anatomic bypass for aorto-iliac occlusive disease in octogenarians.

Fifteen patients over 80 years of age with aorto-iliac occlusive disease (AIOD) underwent surgical revascularization of an ischemic lower extremity by extra-anatomic bypasses. The mean age at operation was 81.7 years, ranging from 80 to 86 years. Surgical revascularization of the ischemic lower limbs could safely be performed with an extra-anatomic bypass in these patients without any major complications. The mean follow-up period was 32.7 months. Eight patients died during the follow-up, only one of them died from myo-nephropathic metabolic syndrome related to acute graft occlusion. As a long-term result, the cumulative survival after 37 months was only 23.9%, while the actual graft patency rate was 43.8% after 60 months in this series. The survival period with an improved quality of life after surgical intervention reached a level of approximately 40% of that for the general population. There should be no hesitation over whether to carry out surgical intervention for AIOD in patients over 80 years of age, because a reasonable extension of life can be obtained by an extra-anatomic bypass.

Aged↗
PubMed1993

A reconsideration of surgery for mitral stenosis based on the extent of valvular distortion shown by two-dimensional echocardiography preoperatively.

A twelve-year follow-up study was carried out with 98 consecutive patients operated on for pure mitral stenosis with open mitral commissurotomy (OMC) or valve replacement with porcine valves (MVR). Each patient had the extent of valve distortion diagnosed preoperatively by two-dimensional echocardiography as either grade I of the dome-formation type, grade II of the intermediate type, or grade III of the mass-formation type. Thirty grade I patients and 24 grade II patients underwent OMC and 44 grade III patients received MVR. The long-term survival and reoperation rates were significantly poorer with grade II than grade I patients and there was no statistical significance between grades II and III. However, the clinical conditions set by NYHA are significantly worse in grade II than in grade III. This can be clearly explained by the fact that the left atrial volume decreasing ratio (LAVDR) in the latest period, which was measured in patients with more than 7 years survival, remained nearly at the early postoperative value in grade III, while the LAVDR of grade II at the latest period grew worse and became insignificantly different from the preoperative values. This study clearly shows that when OMC is applied to grade II patients, frequent reoperations might be necessary because of poor hemodynamic conditions. Thus, it might be better to adopt MVR rather than OMC with grade II patients with moderately distorted mitral valves.

Actuarial Analysis↗
PubMed1993

[Right thoracotomy to approach mitral or tricuspid valve in reoperation].

Four patients underwent mitral valve re-replacement, and required tricuspid annuloplasty in two, through a right thoracotomy. There was no major postoperative morbidity and recovery was full and uneventful. The indications for selection of this approach were isolated mitral valve disease or combined tricuspid and mitral valve disease, severe adhesion between heart and sternum on CT scan, intact aortic valve and no severe reduction of respiratory function. We recommend right thoracotomy to approach atrioventricular valves in selected situations in patients for reoperations.

Aged↗