[Cardiac surgery for renal failure patients;operative and postoperative management].

Chronic kidney disease( CKD) is defined as one of the major risk factors affecting postoperative morbidity and mortality after cardiovascular surgery, and CKD accounts for approximately 9.2~13.7% of the patients undergoing cardiovascular surgery in Japan according to the reports from Japan Adult Cardiovascular Surgery Database (JACVSD). The recent concept on renal dysfunction, recent discussions on the choice of operative procedures[ off-pump coronary artery bypass grafting( CABG)[OPCAB] vs on-pump CABG, bioprosthesis vs mechanical valve prosthesis] and peri-operative managements( electrolyte control, pharmacological management) are also introduced in the text.

Acceleration of arteriosclerosis of the rat aorta allograft by insulin growth factor-I.

We demonstrate here, for the first time, the mitogenic effect of insulin-like growth factor-I (IGF-I) on the development of transplant arteriosclerosis in a rat orthotopic aorta allotransplantation model (Brown Norway to Lewis). 125I-IGF-I uptake by the abdominal aorta of male Brown Norway rats occurred within 30 min. Consequently, we exposed the donor abdominal aorta to 0, 200, or 500 ng/ml IGF-I at 37 degrees C for 30 min ex vivo (n=7 per group), before transplantation. Fourteen days after transplantation, intimal thickening of the allografts in each of the three groups was 0.18+/-0.02 (IGF-I at 0 ng/ml), 0.23+/-0.03 (IGF-I at 200 ng/ml), and 0.30+/-0.03 (IGF-I at 500 ng/ml), respectively (mean+/-SEM, P<0.005 for 500 ng/ml vs. 0 ng/ml). [3H]thymidine incorporation (cpm/microg protein) in the transplanted grafts at 7 days after transplantation (n=4 per group) was 40.6+/-7.6, 78.5+/-12.3, and 66.9+/-10.1, respectively (P<0.01 for 200 ng/ml vs. 0 ng/ml). [3H]thymidine incorporation in the native thoracic aorta of the recipient was 23.4+/-4.4. We conclude that acceleration of allograft myointimal proliferation and intimal thickening was induced directly by IGF-I.

Estradiol inhibits allograft-inducible major histocompatibility complex class II antigen expression and transplant arteriosclerosis in the absence of immunosuppression.

BACKGROUND: The etiology of transplant arteriosclerosis is unknown, but current data point to the alloimmune response. Previously, we found that estradiol-17beta (E2) with immunosuppressant cyclosporine abolishes major histocompatibility complex (MHC) class II expression in the allograft. This study determines the effect of E2 on MHC class II antigen expression in the allograft, in the absence of immunosuppression. METHODS: Lewis male rats received orthotopic abdominal aorta allografts from male Brown-Norway rats. The recipients were treated continuously subcutaneously with either 20 microg x kg(-1) x day1 of E2 (n=20) or placebo (n=20), from 2 days before transplantation until death on posttransplant days 1, 3, 7, and 14. The allografts were harvested and processed for morphometry and for immunohistochemical staining of MHC class II antigens, macrophages, CD4 and CD8 T lymphocytes, interferon-gamma (IFN-gamma), and IFN-gamma receptor. RESULTS: With E2 treatment, we observed that inducible MHC class II antigen expression is abolished in the media of the vascular allograft; the expression of IFN-gamma and IFN-gamma receptor is unaffected; and macrophage infiltration of the vascular allograft is inhibited significantly (P<0.01), whereas the CD4 and CD8 T lymphocytes are not significantly (P=0.07) suppressed. The myointimal hyperplasia in the allografts from E2-treated-recipients was 3-4-fold less than that from the placebo-treated recipients. CONCLUSIONS: Without immunosuppression, E2 inhibition of transplant arteriosclerosis is still associated with inhibition of inducible MHC class II antigen expression in the allografts. The estradiol-17beta abolition of inducible MHC class II antigen expression in the aorta allograft occurs in spite of up-regulation of IFN-gamma ligand and receptor protein.

Exposure of vascular allografts to insulin-like growth factor-I (IGF-I) increases vascular expression of IGF-I ligand and receptor protein and accelerates arteriosclerosis in rats.

BACKGROUND: Accelerated arteriosclerosis limits the survival of transplanted hearts. We hypothesized that insulin-like growth factor-I (IGF-I) is crucial in accelerating transplant arteriosclerosis. Recently, we reported that exposure to IGF-I prior to transplantation accelerates transplant arteriosclerosis in the rat aorta allograft model. Here, we studied the mechanism whereby IGF-I exposure accelerates transplant arteriosclerosis. METHODS: The abdominal aorta was harvested from male Brown Norway rats and exposed to 0, 200, or 500 ng/ml of IGF-I at 37 degrees C for 30 min prior to transplantation to the abdominal position of male Lewis rats. The allografts were harvested 14 days later and processed for immunohistochemical staining for alpha-actin, growth factors (IGF-I, IGF-I receptor, platelet-derived growth factor-BB, and basic fibroblast growth factor), and immunological markers (major histocompatibility complex class II antigen, macrophage, and CD4- and CD8-positive T cells). RESULTS: By 14 days, the ex vivo IGF-I donor aorta treatment with IGF-I increased in a concentration-dependent manner the expression of IGF-I and IGF-I receptor in both the intima and the adventitia. In contrast, the expression of platelet-derived growth factor-BB was decreased in a concentration-dependent manner in the intima while basic fibroblast growth factor remained unchanged. The cell-mediated immune response was not affected by IGF-I at 14 days after transplantation, which suggests that the immune events associated with acceleration of transplant arteriosclerosis may occur at an earlier time. CONCLUSION: Acceleration of transplant arteriosclerosis by exposure to IGF-I is associated with increased IGF-I ligand and receptor expression in the allograft vascular wall. These data further suggest that IGF-I may be a major factor in mediating graft arteriosclerosis.

Compton scatter compensation using the triple-energy window method for single- and dual-isotope SPECT.

The spatial distribution of scattered photons varies depending on many factors such as object size and source distribution. We propose a triple-energy window (TEW) scatter compensation method for determining position-dependent Compton scatter. We estimated the count of primary photons at each pixel in the acquired image using the 24% main window centered at the photo peak energy and 3 keV scatter rejection windows on both sides of the main window. We conducted a physical evaluation of this method using phantoms and also applied this method to patients in a clinical trial. The TEW method performed Compton scatter compensation with good accuracy.

A simulation of dynamic SPECT using radiopharmaceuticals with rapid clearance.

Data acquisition in SPECT assumes that there is no change in radionuclide distribution during data collection. However, this assumption is not valid in radiopharmaceuticals with rapid temporal changes in radioactivity. Artifacts and quantitative errors are studied using phantom studies, mathematical models, and clinical myocardial data. Projection data of each model were sequentially multiplied by weighting coefficients that varied mono-exponentially with time, and the SPECT images were reconstructed. A long data acquisition time in comparison to the clearance of the tracer can be a significant cause of artifact. When the myocardial septum-to-lateral count ratio is used as an index of distortion, a shorter acquisition time than the effective half-life of the tracer is required to reduce the error of the septum-to-lateral count ratio to within 10%. Since 180 degrees rotation acquisition causes artifacts depending on the direction of rotation, 360 degrees acquisition is preferable. Continuous repetitive rotation acquisition is a suitable method for dynamic SPECT to reduce quantitative errors and artifacts.

Scatter and attenuation correction in technetium-99m brain SPECT.

UNLABELLED: We propose a practical method for scatter and attenuation compensation in 99mTc-ECD brain SPECT using a simultaneous emission CT (ECT) and transmission CT (TCT) acquisition system that includes the following major components: (a) triple-headed SPECT gamma camera equipped with fanbeam collimators; (b) external line sources containing 99mTc placed at the focal lines of the collimators; and (c) scatter correction by the triple-energy-window (TEW) method. METHODS: Projection images were obtained over a 360 degrees rotation scan. After acquisition, scatter correction was performed using the TEW method, which corrected scattered photons pixel by pixel in the projection data. Scatter-corrected ECT images were compensated for attenuation using the TCT images with Chang's iterative method, and were converted to activity concentration (kBq/ml) images by obtaining a cross-calibration scan. After validating this method with phantom studies, it was applied to clinical brain imaging using a combination of 925 MBq 99mTc-ECD as a radiopharmaceutical and 222 MBq 99mTc as an external source. ECT and TCT data were acquired separately or simultaneously. RESULTS: SPECT quantification and image quality were improved by performing this correction. The activity concentration images obtained with the simultaneous acquisition were almost identical to those obtained with the separate acquisition. CONCLUSION: This method was clinically practical and cost-effective for reconstructing quantitative 99mTc brain SPECT images.

Feasibility of simultaneous stress 99mTc-sestamibi/rest 201Tl dual-isotope myocardial perfusion SPECT in the detection of coronary artery disease.

UNLABELLED: This study assesses feasibility and diagnostic accuracy of simultaneous stress 99mTc-sestamibi/rest 201 TI dual-isotope myocardial perfusion SPECT with Moore's correction method, in which contamination originating from lead x-rays produced in a collimator was subtracted in the 201TI windows. METHODS: Eighty-one patients with suspected coronary artery disease received exercise 99mTc-sestamibi injection, followed by rest 201TI injection 50 min later, and dual-isotope SPECT was performed (group 1). These results were compared with coronary angiographic findings. Furthermore, to estimate the accuracy of Moore's correction method, 201TI crosstalk into the 99mTc acquisition window (group 2A, n = 20) and 99mTc crosstalk into the 201TI acquisition windows (group 2B, n = 20) were studied. For group 2A, stress 99mTc-sestamibi SPECT (single 99mTc-sestamibi SPECT) was performed, followed by 201TI injection at rest and dual-isotope SPECT acquisition 50 min later. For group 2B, rest 201TI SPECT (single 201TI SPECT) was performed, followed by 99mTc-sestamibi injection at rest and dual-isotope SPECT acquisition 30 min later. RESULTS: Sensitivity and specificity in group 1 were 83% and 99%, respectively, when > or =75% coronary artery narrowing was considered significant. In groups 2A and 2B, SPECT images were divided into 24 segments, and relative regional uptake in each segment was obtained. In group 2A, relative regional uptake of single 99mTc-sestamibi SPECT correlated well with that of dual-isotope SPECT (r = 0.942). In group 2B, relative regional uptake of single 201TI SPECT correlated well with that of dual-isotope SPECT (r = 0.935). Furthermore, in low 201TI uptake segments with relative regional uptake in both single- and dual-isotope SPECT of < or =70%, the degree of concordance between single- and dual-rest 201TI was considered to be high with Bland-Altman analysis and the kappa statistic. Comparison of perfusion defect type demonstrated that, of 22 stress defects within infarct zones, 95% were irreversible and 5% were reversible. In contrast, of 28 stress defects within stenosed vessel zones in noninfarct zones, 89% were reversible and 11% were irreversible (P < 0.0001 versus infarct zones). CONCLUSION: Simultaneous dual-isotope imaging with Moore's correction method is feasible, with acceptable accuracy for detection of coronary artery disease and a small amount of crosstalk into each window.

Specific effects of estrogen on growth factor and major histocompatibility complex class II antigen expression in rat aortic allograft.

OBJECTIVE: Transplant arteriosclerosis is the major determinant for long-term survival of cardiac transplants. Estradiol treatment inhibits transplant arteriosclerosis. The objective of this study is to determine, in the absence of immunosuppression, the temporal effect of estradiol treatment on the expression of insulin-like growth factor, platelet-derived growth factor, basic fibroblast growth factor, and major histocompatibility complex class II antigen in rat aortic allografts. METHODS: Orthotopic abdominal aortic allograft transplantation was performed in male rats with Brown-Norway rats used as donors and Lewis rats as recipients. The recipients (n = 50) were treated with estradiol 20 micrograms/kg per day or placebo by osmotic minipump for 2 days before the operation and until they were put to death on postoperative days 1, 3, 7, 14, or 21. The allografts were harvested and insulin-like growth factor, platelet-derived growth factor, basic fibroblast growth factor, and major histocompatibility complex class II antigen expression were determined by immunohistochemical staining. Myointimal thickening was measured by morphometric analysis. RESULTS: In the placebo-treated group, insulin-like growth factor protein progressively increased in all three layers of the allograft, whereas platelet-derived growth factor protein peaked at day 3 and basic fibroblast growth factor protein increased only moderately. Estradiol treatment inhibited the continuous increase in insulin-like growth factor expression, the peak in platelet-derived growth factor expression at day 3, the moderate-basic fibroblast growth factor increase at day 21, and major histocompatibility complex class II antigen expression in all three layers of the allograft at day 21. Intimal thickening of allografts from estradiol-treated recipients was twofold to threefold less than that of the placebo-treated recipients at day 21. CONCLUSION: The development of transplant arteriosclerosis is associated with an early alloimmune response involving sustained increase in insulin-like growth factor expression. Estradiol treatment of the recipient inhibits transplant arteriosclerosis and suppresses insulin-like growth factor and major histocompatibility complex class II antigen expression but not platelet-derived growth factor or basic fibroblast growth factor in all three layers of the allograft during the early posttransplantation alloimmune rejection phase.

Histologic modification by cryopreservation in rat aortic allografts.

Histologic changes after the cryopreserved rat aortic transplantation were studied, and the influences of the cryopreservation and of the allografting on the histology were examined. Four groups of Brown Norway (RT1n) and Lewis rats (RT1(1)) were used (n = 4 at each examined period in each group): the cryopreservation-allograft group (from Brown Norway to Lewis with cryopreservation), the cryopreservation-isograft group (from Lewis to Lewis with cryopreservation), the fresh allograft group (from Brown Norway to Lewis without cryopreservation), and the fresh isograft group (from Lewis to Lewis without cryopreservation). The graft was harvested from a descending thoracic aorta of a donor rat, implanted to an infrarenal abdominal aorta of a recipient rat, and extracted at 10 days, 1, 3, 6, and 12 months after the operation. The intimal thickening, cellular loss in the media, and cellular infiltration in the adventitia were observed, which were the same phenomena seen in chronic rejection of human organ allografts. Although the degree of intimal thickening and cellular loss in the media were higher in the cryopreserved groups than in the fresh groups, the cryopreservation procedure suppressed cellular infiltration in the adventitia after allotransplantation. The immunologic attack against the graft might be diminished by cryopreservation.

Quantitative planar imaging method for measurement of renal activity by using a conjugate-emission image and transmission data.

We are proposing a method to accurately measure renal activity in renography using Tc-99m labeled tracers. This method uses a conjugate-view image and transmission data for attenuation correction, the triple energy window (TEW) method for scatter correction, and background correction techniques that consider the source volume for accurate background activity correction. To examine this method in planar imaging, we performed two renal phantom studies with various uniform background activity concentrations. One study used two ideal box-shaped kidney phantoms with a thickness of 2 or 4 cm in a water tank and the other study employed two real kidney-shaped phantoms in a fillable abdominal cavity. For these studies the kidney phantom-to-background activity concentration ratio (S) was changed from 5 to infinity. The transmission data were obtained with an external Tc-99m line array source. The anterior- and posterior-view emission images were acquired with a dual-headed gamma camera simultaneously and the TEW method was used to correct scatter for the emission and transmission images. The results showed that this method with both the accurate background correction and scatter correction could give depth-independent count rates and could estimate the true count rate with errors of less than 5% for all S values. However, if either accurate background correction or scatter correction was performed alone, the absolute error increased to about 50% for the smaller S values. Our proposed method allows one to accurately and simply measure the renal radioactivity by planar imaging using the conjugate-emission image and transmission data.

A case of ideational apraxia with impairment of object use and preservation of object pantomime.

A case of tool use disturbance without impairment of motor skills and of conceptual knowledge of how tool must be used is reported. The patient could not manipulate objects isolatedly or in succession but could pantomime their use on command and on imitation. This finding suggests that manipulation of objects may dissociate from pantomime without objects. We interpret this syndrome as a results of mismatch of tool and tool use.

Failure to manipulate objects secondary to active touch disturbance.

A peculiar type of sensori-motor disturbance consequent to a lesion in the contralateral postcentral gyrus was reported. The symptom was characterized by motor clumsiness of the left hand without loss of strength and with preserved finger movements on visual imitation. Motor difficulty was most marked when the patient had to manipulate an object. The analysis of the patient's behavior and of his sensory deficits suggests that the basis of the clumsiness was a deficit in active touch perception.

HMG-CoA reductase inhibitors in organ transplantation.

Hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors reduces serum cholesterol in patients with high cholesterol blood levels including organ transplant recipients. HMG-CoA reductase inhibitor also inhibits a series of immune responses and thus have the potential of exerting immunosuppressive effect in patients with organ allografts. Experimentally, HMG-CoA reductase inhibitors reduces transplant arteriosclerosis. Whether this is linked to an immunosuppressive effect or not is unknown. There is little evidence that post-transplant hyperlipidemia directly increases the risk of cardiovascular diseases. Lipid lowering with HMG-CoA reductase inhibitor is not indicated for all allograft recipients but should be used if other cardiovascular risk factors are present.

Aortic root replacement with a cryopreserved aortic homograft in a patient with giant cell aortitis following two Bentall's type operations.

Patients with aortic valvular regurgitation due to non-infectious aortitis are at high risk of valve detachment. In this report, a patient with giant cell aortitis is described, who underwent successful aortic root replacement with a cryopreserved aortic homograft, following two Bentall's type operations that resulted in graft detachment.

Aortic root replacement and coronary interposition using a cryopreserved allograft and its branch.

This communication describes a modified aortic root replacement technique using a cryopreserved allograft consisting of the aortic conduit and its branch. This method was applied in a patient suffering from infective pseudoaneurysm which had developed after aortic root replacement using an artificial graft with a mechanical aortic valve. A piece of the innominate artery obtained from the aortic allograft was used for interposition between the fragile left coronary artery root and the main conduit of the allograft.

Thoracoscopy for minimally invasive axillo-coronary artery bypass.

Minimally invasive axillo-coronary artery bypass via a small thoracotomy or a limited sternotomy was performed in five patients. For this approach, videoscopy was used to determine the intrapleural path of each vein graft, which was curved by the expanded lung tissue and had the potential for kinking or distortion. Postoperative angiography confirmed the patency of each graft with no kinking or distortion. Thoracoscopy facilitates this approach, allowing appropriate placement of the vein graft in the chest cavity.

Effects of scatter and attenuation correction on quantitative analysis of beta-CIT brain SPET.

The aim of this study was to evaluate the effects of scatter correction (SC) and attenuation correction (AC) on the quantification of dopamine transporters using 123I-beta-CIT brain SPET images. Quantitative analysis was carried out using static SPET images obtained 23 h after injection. We calculated V3" [(striatal-occipital)/occipital ratio] values from images without correction, with AC, and with SC and AC. Two types of regions of interest (ROI) were placed on the striatum: a small square ROI and a larger ROI containing most of the striatum. After validating the correction method in a phantom experiment, a human study was carried out involving eight normal volunteers and 15 patients. The larger ROI yielded smaller V3" values. The effect of attenuation correction was modest, whereas that of scatter correction was marked. It was shown that beta-CIT SPET quantification was affected by the size of the ROI, photon scattering and attenuation, and that scatter and attenuation correction improved the accuracy of the quantification. Methodological standardization in image processing and the type of ROI should be considered when a multi-centre trial is planned.

Histological change in cryopreserved rat aortic allograft.

In this study, we established an experimental cryopreserved aortic allograft model in rats and examined the long-term histological changes in the allograft. The thoracic aorta of Brown Norway rats (RT1n) was cryopreserved with 10% dimethylsulfoxide using a programmable freezer, and was allo-transplanted to the infrarenal abdominal aorta of Lewis rats (RT1l). Neither immunosuppressants nor anticoagulants were administered postoperatively. As a control, isografting was also performed between Lewis donor and recipient rats. In the allograft groups, cellular infiltration in the adventitia was massive at the acute phase after the operation and decreased gradually. Intimal thickening was predominantly observed from the early stage, followed by advancing thickening. In the media, decrease in cell number was detected after 1 month, and chondrocyte-like-cells were observed around which calcification was noted. Endothelial cells were observed in only one-third of the recipient investigated at 10 days and in over 80% of those at 12 months. In the isograft groups, a low grade of intimal thickening was detected over the experimental period. No decrease in cell number in the media was detected, and the degree of cellular infiltration in the adventitia was mild. After allotransplantation of the cryopreserved rat aorta, intimal thickening, medial necrosis and cellular infiltration in the adventitia, all the manifestations of rejection, occurred. Thus, as the cryopreserved tissue induces an immunological response, it is important to match the blood type and/or histocompatibility in clinical use.

Angiopeptin as a potent inhibitor of myointimal hyperplasia. Systemic injection and local administration via impregnation in a biodegradable polymeric gel.

We studied a pharmacologic approach using a potent peptidyl antiproliferative agent, angiopeptin, to prevent the myointimal hyperplasia that occurs as a diseased vessel is replaced with an artificial graft or treated by an intravascular device. In vitro cell culture studies showed that the proliferative potential of smooth muscle cells was dose dependently reduced, whereas the migratory response was reduced to a lesser degree. In a well defined injured rat artery model, in which a denuded aorta was prepared by collagenase treatment, followed by isotransplantation, a remarkable suppressive effect of angiopeptin on myointimal hyperplasia was observed with daily subcutaneous injection. Local sustained release from a biodegradable polymeric gel coated on an injured vessel was also effective in the prevention of myointimal hyperplasia. Slightly retarded endothelial regeneration was noticed. The potential application to small caliber artificial grafts is discussed.