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Biomedical subjects

S Imawaki

Publications and source records attributed to S Imawaki.

At least 19 recordsLinked to original sources
PubMed1996

[A case of new stenosis in the distal portion following transaortic patch angioplasty for the left main coronary stenosis].

A 75-year-old man who had unstable angina underwent transaortic vein patch angioplasty for isolated 60% stenosis of the left main coronary artery. About four months after the operation, he developed effort angina and angiographycally new stenosis was detected in the distal portion of patch dilatation. So he underwent emergency aorto coronary bypass grafting. Transaortic patch angioplasty is attractive technique because of restoration of the original antegrade coronary flow, but this direct surgical approach may induce the stimulation of intima, and may injure the intima. It is important to bear this technique in the mind for selected patients with left main coronary lesions.

Aged↗
PubMed1995

Effects of left intraatrial infusion of prostaglandin E1 after open-heart surgery.

The hemodynamic effects of a left intraatrial infusion of prostaglandin E1 (PGE1) given to ten patients after open-heart surgery (LA group), were compared with those following no treatment in a control group of ten patients, and to those following a right intraatrial infusion given to another ten patients (RA group). PGE1 was infused at a rate of 0.03 microgram/kg/min in the RA group and at 0.003 microgram/kg/min in the LA group, and hemodynamics were measured immediately after surgery, then 3, 6, and 12 h after the PGE1 infusion was commenced. The heart rate, right atrial pressure, left atrial pressure, and mean pulmonary arterial pressure remained almost unchanged in all three groups; however, the mean radial arterial pressure and systemic vascular resistance index decreased, and the cardiac index increased in the RA and LA groups. The pulmonary vascular resistance index decreased only in the LA group. Thus, a much smaller dose of PGE1, being one-tenth of that used for the right atrial infusion, administered directly into the left atrium yielded almost the same hemodynamic effects as the larger dose infused into the right atrium. Furthermore, this method of infusing PGE1 is safe, efficacious, and cost-efficient.

Adult↗
PubMed1995

Development of a fistula between an internal mammary artery graft and the pulmonary vasculature following coronary artery bypass grafting: report of a case.

We report herein the rare case of a 56-year-old man who gradually developed congestive cardiac failure 6 months after undergoing coronary artery bypass grafting and was found to have a fistula between the internal mammary artery and the pulmonary artery of the upper lobe diagnosed by selective left internal mammary arteriogram. A second sternotomy was performed and demonstrated dense adhesion between the fissure surrounding the internal mammary artery and the upper lobe, and the fistula was resected. We believe that the patient's increasing cardiac failure was almost certainly caused by coronary seal.

Arterio-Arterial Fistula↗
PubMed1994

Chordal reconstruction with polytetrafluoroethylene (PTFE) sutures for mitral regurgitation.

Chordal reconstruction of the mitral valve using CV4 or CV5 polytetrafluoroethylene (PTFE) (Gore-Tex. Flagstaff, AZ, USA) sutures was performed in seven patients with mitral regurgitation (MR) to ascertain its efficacy. The MR had been caused by prolapse of the anterior leaflet in three patients, the posterior leaflet in two, and both leaflets in two; five of the patients had an MR of grade III or IV. There was one hospital death, which occurred in a patient whose MR had resulted from papillary muscle dysfunction caused by a myocardial infarction (MI). Chordal reconstruction failed and was converted to a mitral valve replacement in two patients, one of whom had suffered a MI and another who had a congenital papillary muscle anomaly. The remaining five patients all underwent successful chordal reconstruction with PTFE sutures, resulting in the disappearance of the MR in two patients and an improvement to grade I in three patients. Although the longest follow-up period has been only 1 year, the MR has not worsened. This technique is relatively easy to perform, and allows almost all the mitral apparatus to remain in situ, while enabling repair of the mitral valve, regardless of the state of the diseased chordae.

Adult↗
PubMed1994

[Is it safe and available to transfuse directly the shed mediastinal blood after cardiac surgery?].

Autotransfusion of the shed mediastinal blood after cardiac operations was performed in 20 cases (ATS group). Safety and efficacy of the autotransfusion were studied comparing with the 10 cases without autotransfusion (control group). A 65.1 +/- 17.1% of bleeding volume within 24 hours after surgery was autotransfused in the ATS group. The ATS group received 1,396 +/- 1,674 ml of the banked blood compared with 780 +/- 1,194 ml for the control group. There was no significant difference between two groups in regard to saving the banked blood. Hematological and biochemical studies after surgery in the ATS and control groups revealed that CPK, BUN and creatinine of the ATS group were significantly higher than those of the control group, although these changes were transitory and trivial. However, prothrombin time of the ATS group was lower than that of control group, so there may be the possibility that this technique itself increases the hemorrhage. Since the cardiotomy filter was obstructed with clots in cases of massive bleeding, shed mediastinal blood may not be fully defibrinogenated in the cases with massive bleeding. These results lead to the following conclusions: autotransfusion of the shed mediastinal blood after cardiac operations is a safe method, but the efficacy of it is doubtful.

Adult↗
PubMed1993

Decrease in aortic distensibility after an extended aortic reconstruction for Marfan's syndrome as a cause of postoperative acute aortic dissection DeBakey type I: a report of two cases.

Two cases of Marfan's syndrome underwent a reconstruction of the abdominal aorta and descending thoracic aorta. A replacement of the abdominal aorta with visceral arteries as well as a wrapping of the descending thoracic aorta was performed in case 1 while a reconstruction of the descending thoracic aorta and infra-renal abdominal aorta was done in case 2. After the reconstruction, both cases developed acute aortic dissection DeBakey type I. Another reconstruction of the ascending aorta was then urgently performed. Cardiac catheterization after the second operation in case 1 revealed that the distensibility of the aorta had disappeared at the location of the vascular prosthesis while it had also decreased at the wrapped portion, and the maximum dp/dt of the ascending aorta also increased. Increases in the pulse pressure and pulse rate after the first operation were observed in both cases. These hemodynamic changes, which were produced by a decreased distensibility of the reconstructed aorta, increased the mechanical stress to the native aortic wall, and may have been one of the causes of acute aortic dissection DeBakey type I occurring after reconstruction with a prosthesis.

Acute Disease↗
PubMed1993

[Chordal reconstruction with polytetrafluoroethylene (PTFE) suture for mitral regurgitation caused by prolapsed anterior leaflet].

Cardiac surgeons have hesitated to perform valvuloplasty for MR caused by elongated or ruptured chordae of the anterior leaflet (AL) of the mitral valve. We experienced three cases of successful chordal reconstruction (CR) to the AL last year. Two of them were due to elongation of all chordae tendineae to the AL. Four CRs, one chordal shortening, cleft closure and ring annuloplasty (AP) were performed in one case, and 8 CRs to the AL, two to the posterior leaflet, commissural closure and ring AP in another. In the third case 2 CRs combined with Reed's AP, closure of ASD and tricuspid AP were performed. The MR disappeared in one case and improved to grade I in others postoperatively. NYHA classes improved from class III or IV to I or II postoperatively. The MRs have not increased 6 to 12 months after the surgery. The CR with PTFE suture enabled to do the valvuloplasty for the chordal abnormalities of the AL without valve resection. This technique seems to be adequate for repairing a major prolapse of the AL caused by multiple chordal abnormalities.

Adult↗
PubMed1993

[Patch angioplasty for isolated ostial stenosis of the left coronary artery].

Two patients with isolated coronary ostial stenosis were successfully treated by patch angioplasty. These two cases were compared angiographically with 49 conventional CABGs for distal coronary stenosis. The patch angioplasty of the ostium can create an large internal diameter, prevent competitive flows, and can be made under limited dissection at reoperation. For isolated coronary ostial stenosis this method is superior to the CABG to the left anterior descending and/or circumflex coronary arteries in which retrograde flow or stasis may occurred.

Adult↗
PubMed1992

[Indication of pulmonary embolectomy for acute pulmonary embolism].

During the past 7 years, 15 patients with acute pulmonary embolism (APE) were treated at Kagawa Medical School and 10 patients were survived. Nine patients had an embolus in a right or left pulmonary trunk (group A) and 6 patients were peripheral APE (group B). In group A abnormal findings in a chest x-ray film and an electrocardiogram were observed in many patients, but in group B these findings were slight. In group A a shock was observed in 89% and cardiac arrest in 4 patients, although in group B neither shock nor death were observed. Marked hypoxia with hypocapnia was observed in 8 patients in group A and only in 2 in group B. All patients in group B were recovered by medical therapy. In group A, however, only 3 patients were recovered by medical therapy. Two patients in group A were performed pulmonary embolectomy (PER), but one of them, who had been in nonreversible shock, died. We conclude that the patient who had marked hypoxia (PO2 less than or equal to 50 mmHg) with hypocapnia (PCO2 less than or equal to 35 mmHg) early at an attack should be taken a pulmonary angiography, and when a large embolus is found out in the proximal pulmonary artery, the PER should be performed as soon as possible.

Acute Disease↗
PubMed1992

[Clinical profile and treatment of acute pulmonary embolism].

The clinical profiles of 15 patients with acute pulmonary embolism (APE) were analysed. The most common symptoms of APE were tachypnea and tachycardia with sudden onset. Both PO2 and PCO2 had decreased in almost all patients (mean PO2: 50 mmHg, PCO2: 30 mmHg). Chest roentgenogram (X-P) revealed hyperlucency of the lung field, prominence of proximal pulmonary artery and cardiac enlargement. ECG showed SI QIII TIII and ST-T changes in half of the cases. These changes, however, disappeared within 4 days in most patients. Lung scan and digital subtraction pulmonary angiography were useful for the diagnosis. Sixty percent of patients recovered only by medical therapy, and embolectomy was performed in only two patients. Fifty-three percent of patients were, however, considered to be candidates for the embolectomy, and half of them died because of ineffective medical therapy. From these results we concluded that the combination of severe hypoxemia and hypocapnia with abnormal chest X-P can be used for a diagnostic or therapeutic decision. If a patient has those findings, pulmonary angiography is recommended together with thrombolytic therapy. If a large embolus is detected, embolectomy is mandatory. The need for surgical therapy for APE is greater than we had imagined.

Acute Disease↗
PubMed1992

[Hematologic and endocrinologic effects of pulsatile cardiopulmonary bypass using a centrifugal pump].

The effects of pulsatile and nonpulsatile flow during cardiopulmonary bypass (CPB) with of centrifugal pump (Sarns) and membrane oxygenator, on blood cells, hemodynamics, and hormonal response were studied. In the pulsatile group (group P) in which pulsatile flow was generated by centrifugal pump and a 20 Fr arterial cannula was used, hemolysis and reduction of platelet count during CPB were more marked than in the nonpulsatile group (group NP), in which the same type of circuit was used. When the 20 Fr arterial cannula was replaced with a 24 Fr cannula (group Pc), the rate of hemolysis during CPB was significantly reduced compared with that in group P (p less than 0.05). The rate of rise in plasma free hemoglobin from 10 to 70 minutes CPB in group Pc was 15.0 mg/dl/hr, this value did not exceed that in either group NP or in group Pr, in which a roller pump rather than centrifugal pump was used to generate pulsatile flow. These findings show that pulsatile CPB with a centrifugal pump produces no deleterious hematologic effect in clinical use. The rise in the level of angiotensin II in group P was significantly smaller than that in group NP (p less than 0.05), and the rise in plasma renin activity and levels of angiotensin I, adrenalin and noradrenaline were smaller than those in group NP, although these differences were no significance. These findings indicate that the centrifugal pump generates pulsatile flow effectively, although not so effectively as to prevent the rise in peripheral vascular resistance. During CPB, there was no change in levels of thyroid hormones, including free T3, free T4 and reverse T3, in either pulsatile groups P and Pc or nonpulsatile group. TSH level in group Pc was significantly elevated in contrast with that in the nonpulsatile group (p less than 0.05), in which no change in TSH level was seen. It is suggested that pulsatile perfusion using a centrifugal pump might maintain sufficient hypothalamic-pituitary function to permit secretion of TSH in response to various stimuli.

Aged↗
PubMed1990

[A case of ventricular septal perforation with bidirectional shunt and Hegglin like syndrome].

A 47-year-old man with ventricular septal perforation (VSP) was repaired successfully. His preoperative examinations revealed Hegglin like syndrome with fixed and split second heart sound due to early closure of aortic valve (QT-Q II A = 58 ms), and bidirectional shunt through the VSP. These abnormal phenomena occurred due to shortening of left ventricular ejection time and prolongation of right ventricular ejection time, and were completely abolished after the operation.

Cardiac Catheterization↗
PubMed1990

[Differences in loading condition and its effects for valve replacement between chronic aortic and mitral regurgitation].

In order to clarify the differences of left ventricular mechanics between chronic aortic and mitral regurgitation (AR and MR), 23 patients with AR and 17 patients with MR were studied by noninvasive techniques. There were no differences between two types of regurgitation in R/Th, LV dimension, LVEDVI, PWTd, LV mass I and mean blood pressure. However, the peak systolic wall stress (PSWS), ESVI and systolic blood pressure (sBP) of AR were significantly higher than that of MR. One month after valve replacement (VR), in AR all parameters decreased significantly expect increased PWTd. But in MR, blood pressure, LV systolic size and LV mass I were unchanged, although LVDd, LVEDVI, PSWS and R/Th decreased significantly. These results indicates that high PSWS in AR is diminished effectively after AVR by both effects of reduction of LV volume and sBP, although in MR, as a sBP is kept in low level, a drop of PSWS after MVR occurs only due to reduction of volume. Therefore, systolic function after MVR for MR with impaired myocardium may be more destroyed by relatively high afterload as it is difficult to diminish the volume, even if LV function was kept relatively in good condition before operation.

Adult↗
PubMed1989

[A technique of end-to-side anastomosis of a prosthetic graft to the ascending aorta: reinforcement of the anastomosis with wrapping of the ascending aorta].

In temporary, permanent or extra-anatomic bypass grafting to the side of the ascending aorta, a technique of prosthetic fabric wrapping of the ascending aorta associated with reinforcement of the anastomosis is devised as a simple and useful method for aortic surgery. With this technique, dislodgement of the vascular forceps can be prevented completely, and the ascending aortic wall may be protected from injuries owing to the vascular forceps.

Anastomosis, Surgical↗
PubMed1989

[Surgical treatment of acute pulmonary embolism--report of two cases].

Two surgical cases of acute pulmonary embolism with severe cardiocirculatory impairment were reported. In the first case, emergent open pulmonary embolectomy with cardiopulmonary bypass was not effective, and multiple and organized emboli were indicative. In the second case, complete pulmonary thromboembolectomy was accomplished under extracorporeal circulation with remarkable hemodynamic improvement. It was suggested that urgent pulmonary angiography was necessary for definitive diagnosis and medical treatment, and that indications for pulmonary embolectomy included all patients with massive emboli in the main branches of the pulmonary artery. Monitoring of pulmonary arterial pressure was important to assess the effect of thrombolytic therapy, and the system of emergent cardiopulmonary bypass was required for immediate and effective cardiopulmonary resuscitation.

Acute Disease↗
PubMed1989

[A case of cardiac myxoma associated with long-term lasting symptoms of mitral stenosis].

We reported a case of 70-year-old woman whose left atrial myxoma was resected. She had been suffered from low cardiac output due to mitral stenosis for 15 years or more. Resection of the myxoma corrected mitral stenosis completely. Cardiac output and pulmonary wedge pressure, however, were not improved following the operation. Postoperative echo- and angiocardiography revealed marked early closure of the mitral valve. These findings indicate that left ventricular compliance should be reduced if inflow stenosis continued for a long period and it is difficult to improve depressed ventricular function even if mitral stenosis is completely removed.

Aged↗
PubMed1988

[Extra-anatomic bypass operation of ruptured thoracoabdominal aortic aneurysm].

A successful surgical case of ruptured thoracoabdominal aortic aneurysm of Crawford type III was reported. The patient was a 40-year-old male suffering from cystic kidney, hypertension and dissecting aortic aneurysm. The operative procedure was implantation of a large Dacron graft between the ascending aorta and the common iliac arteries, with branches of small Dacron grafts anastomosed to the left common carotid, left subclavian, celiac, superior mesenteric and renal arteries, and exclusion of the aorta.

Adult↗