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Biomedical subjects

S Kawada

Publications and source records attributed to S Kawada.

At least 37 records · Page 2Linked to original sources
PubMed2000

Selective perfusion of segmental arteries in patients undergoing thoracoabdominal aortic surgery.

BACKGROUND: Reattachment of segmental arteries is one method used to prevent paraplegia associated with thoracoabdominal aortic repair. Nevertheless, even when important segmental arteries are reattached, ischemia causing spinal injury may occur during anastomosis. METHODS: In 27 patients undergoing thoracoabdominal aortic repair, we attempted to perfuse the segmental arteries to be reattached with catheters connected to the distal bypass circuit. To identify perioperative risk factors for spinal ischemia, we examined changes in spinal somatosensory evoked potentials. RESULTS: A median value of four segmental arteries were perfused in 20 (74%) of the 27 patients. Changes in somatosensory evoked potential indicative of spinal ischemia were observed in 13 patients (48%). The only risk factor associated with changes in evoked potentials revealed by a multivariate analysis was prolonged aortic cross-clamp time (> 120 minutes). Of the 2 patients who suffered paraplegia, one had the longest clamp time and the other showed spinal cord necrosis due to embolic shower. CONCLUSIONS: Despite selective perfusion of segmental arteries, spinal ischemia associated with aortic cross-clamping may occur when clamping is prolonged over 120 minutes. Most of the changes appear to be reversible, however.

Adult↗
PubMed2000

Cerebral complications associated with selective perfusion of the arch vessels.

BACKGROUND: Few studies have determined risk factors for postoperative cerebral complications associated with surgery of the aortic arch using selective cerebral perfusion. METHODS: Between November 1992 and December 1998, 113 patients underwent aortic arch repair combined with selective cerebral perfusion. For each patient, three arch vessels were perfused using a single roller pump at a rectal temperature of 23 degrees C. RESULTS: Among the 108 patients who underwent postoperative neurologic assessment, 25 patients (23%) suffered from cerebral complications. Five patients (5%) suffered from transient neurologic disturbance and 17 patients (16%) suffered from stroke, and 7 patients (7%) of the preceding 17 patients had residual neurologic disturbance upon discharge. Three patients (3%) with either preoperative coma (n = 1) or post bypass cardiac arrest (n = 2) sustained severe global cerebral dysfunction. The occurrence of cerebral complications was not related to cerebral perfusion time. Independent risk factors for cerebral complications included a history of cerebrovascular disease, perioperative shock, distal anastomosis below the left pulmonary artery, malperfusion of extremities, and older age (> 60 years). CONCLUSIONS: Although high-level brain function was well preserved in most patients, the incidence of stroke when using current selective cerebral perfusion techniques is still high.

Adult↗
PubMed2000

Exogenous aspartate neurotoxicity in the spinal cord under metabolic stress in vivo.

BACKGROUND: Considerable evidence exists that neurotoxicity of excitatory amino acids is related to the neuronal injury, including paraplegia. However, little is known about aspartate neurotoxicity in the spinal cord in vivo. We evaluated the detrimental effects of exogenous aspartate on spinal cord neurons under metabolic stress. METHODS: New Zealand white rabbits underwent an infrarenal aortic isolation. Group A animals (n = 7) received segmental aspartate 50 mmol/L) infusion for 10 minutes. Group B animals (n = 7) received saline as a negative control. Group C animals (n = 5) received segmental aspartate 100 mmol/L) infusion for 5 minutes. Group D animals (n = 7) were pretreated with segmental infusion of (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cycloheptan-5,10-imine (MK-801) (6 mg/kg), a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist for 1 minute, followed by segmental infusion of aspartate (50 mmol/L) for 9 minutes. Group E animals (n = 7) received vehicle only, followed by aspartate (50 mmol/L) infusion as a control of group D. Neurologic status was assessed at 12, 24, and 48 hours after operation using the Tarlov score. RESULTS: Group A animals exhibited paraplegia or paraparesis with marked neuronal necrosis. Group B and C animals recovered fully. Group D animals showed significantly better neurologic function (p = 0.0007) compared with group E animals that exhibited paraplegia or paraparesis. CONCLUSIONS: Exogenous aspartate can have detrimental effects on spinal cord neurons under metabolic stress. This model may be useful in assaying neuronal injury mediated by NMDA receptor in vivo.

Animals↗
PubMed2000

Surgical management of the straddling mitral valve in the biventricular heart.

BACKGROUND: The straddling mitral valve in the biventricular heart is a rare condition that may complicate biventricular repair. METHODS: Treatment and outcomes in 5 consecutive patients who underwent primary repair between 1992 and 1997 were reviewed. Their ages at repair ranged from 2 months to 8 years. Three patients had a double-outlet right ventricle with a subaortic (n = 2) or subpulmonary (n = 1) ventricular septal defect. Two patients had transposition of the great arteries (S,D,D), a ventricular septal defect, and left ventricular outflow tract obstruction. The attachments of the papillary muscles of the straddling mitral valves were located on the right ventricular aspect of the ventricular septum. Four patients underwent baffle partitioning of the ventricular cavity. The baffle suture line was used to secure the chordae tendineae crossing the ventricular septal defect, or was intentionally omitted at the papillary muscle. The right ventricular outflow tract was reconstructed with patch augmentation, an extracardiac conduit, or an arterial switch operation. One patient with transposition who had a giant papillary muscle to the straddling mitral valve associated with abnormal insertion of the tricuspid valve on the conal septum underwent univentricular repair. RESULTS: There were no early or late postoperative deaths. There was no mitral valve dysfunction, left ventricular outflow tract obstruction, or heart block in the 4 patients who underwent biventricular repair. CONCLUSIONS: Although there are several exceptional situations in which ventricular partitioning may result in early and late complications, a straddling mitral valve does not preclude biventricular repair.

Cardiac Catheterization↗
PubMed2000

Aortoventriculoplasty in patients with aortic malposition.

Aortoventriculoplasty was applied successfully for recurrent combined subvalvular and valvular aortic obstruction that developed after intraventricular baffle repair of a cardiac anomaly in 2 patients with associated anterior malposition of the aorta. A single baffle for the left ventricular tunnel was also used for aortic annulus augmentation.

Adolescent↗
PubMed2000

Acute ischemic hepatic failure resulting from intraaortic balloon pump malposition.

We describe a rare intraaortic balloon pump (IABP) vascular complication as a result of malpositioning of the IABP. A 61-year-old man with unstable angina underwent emergency coronary artery bypass grafting soon after the insertion of an IABP. Postoperative hemodynamics were stable, but acute hepatic dysfunction occurred on the second postoperative day. Doppler echography revealed the absence of hepatic arterial flow. The IABP was removed, and arterial flow was immediately restored. Thereafter, the hepatic function recovered rapidly. This is a rare case that demonstrates how IABP can cause mechanical abdominal arterial branch obstruction. Evaluations using Doppler echography are useful in detecting such IABP complications.

Coronary Artery Bypass↗
PubMed2000

Modified ultrafiltration improves carbon dioxide removal after cardiopulmonary bypass in infants.

Little is known about the role of modified ultrafiltration in ameliorating the adverse effects of the cardiopulmonary bypass on pulmonary function in infants. Twenty-nine nonrandomized consecutive infants (<12 months of age) who underwent unrestrictive ventricular septal defect closure between 1995 and 1998 were included in this study. Down's syndrome was associated in 9 patients. The actual ventilator settings were highly homogeneous among all patients and each time point in the study. Fourteen infants received modified ultrafiltration after the discontinuation of cardiopulmonary bypass. Fifteen untreated patients served as the control group. Correlates of cardiac and pulmonary functions for both groups were compared. The arterial carbon dioxide tension in the experimental group was significantly lower than in the control group from 20 to 240 min after bypass. Arterial oxygenation and pulmonary arterial pressure were similar in the 2 groups. Modified ultrafiltration improves carbon dioxide removal after cardiopulmonary bypass in infants. This may potentially convey a beneficial impact on hemodynamics.

Analysis of Variance↗
PubMed2000

Development of a completely closed circuit using an air filter in a drainage circuit for minimally invasive cardiac surgery.

The completely closed circuit system is the future direction of cardiopulmonary bypass because of its compactness and superior biocompatibility. The most serious obstacle for clinical application is the sucking of air bubbles into the drainage circuit. The purpose of this study was to remove the air bubbles from the drainage circuit. Infusing 50 ml/min of air bubbles into the drainage circuit of the usual closed circuit, and infusing 50, 100, and 150 ml/min of air into the drainage circuit of a newly developed closed circuit (drainage circuit using an air filter), the number and size of air bubbles were observed at the outlet of the arterial filter. In the usual closed circuit, many air bubbles of over 40 microm were detected within 5 s at a blood flow of 4 L/min because the centrifugal pump decreased the size of the bubbles, which then passed through the oxygenator and arterial filter. Air bubbles of over 40 micro were not detected in the newly developed closed circuit within 5 min at a blood flow of 4 L/min. The removal of air mixed into the completely closed circuit was possible with a drainage circuit using an air filter that was developed. The clinical use of the completely closed circuit for minimally invasive cardiac surgery (MICS) became possible based on this development.

Air↗
PubMed2000

Vacuum assisted cardiopulmonary bypass in minimally invasive cardiac surgery: its feasibility and effects on hemolysis.

The present study describes a cardiopulmonary bypass (CPB) technique that incorporates vacuum assisted venous drainage and arterial return using a centrifugal pump in minimally invasive cardiac surgery (MICS). The technique was performed on 40 patients scheduled to undergo MICS. The proposed CPB technique enables a good operative field to be obtained even through a limited incision through the use of peripheral cannulation using small cannulae. Vacuum pressure was applied to the venous reservoir (-43 +/- 14 mm Hg) to maintain adequate CPB flow (>2.4 L x min-1 x M-2). The effects of CPB on hemolysis were subsequently compared between patients who underwent the proposed procedure (MICS group; n = 6) and a control group who underwent coronary arterial bypass grafting (CABG group; n = 6) with conventional CPB. Plasma free hemoglobin (FHb) increased and plasma haptoglobin (Hp) decreased during CPB in both groups, with no significant difference between the groups. By the next day, FHb had returned to pre-CPB levels whereas Hp remained lower in both groups. Again, these values did not differ significantly between groups. Thus, we conclude that the proposed CPB technique is useful in MICS with acceptable effects on hemolysis.

Analysis of Variance↗
PubMed2000

Closed circuit cardiopulmonary bypass with centrifugal pump for open-heart surgery: new trial for air removal.

The purpose of this study is to examine the efficiency of venous air removal with a new cardiopulmonary bypass (CPB) circuit design for conventional open-heart surgeries. A main concern with a closed circuit for open-heart surgeries is air entrainment into the venous line. A venous filter was placed proximal to the centrifugal pump. The circuit proximal to the centrifugal pump was divided into two lines; one line was attached to the venous reservoir outlet. By clamping the line to the reservoir, this circuit becomes closed. Negative pressure was applied to the purge line connected to the venous reservoir for venous air removal. Micro bubbles were measured at two locations, both distal to the venous and arterial filters. When the injection rate reached 100 ml/min, with the air-injection over 30 s, micro bubbles greater than 40 micro were observed at the outlet of venous filter. However, there was no micro bubble greater than 40 micro detected at the outlet of arterial filter. Although micro bubbles greater than 40 micro were not detected at the outlet of the arterial filter up to the injection rate of 300 ml/min, when the injection rate reached 400 ml/min, micro bubbles greater than 50 microm were detected distal to the arterial filter. From this examination, we determined that air entrained in the venous line up to approximately 300 ml/min is automatically removed by this method with the pressure-balanced condition. This pressure balance means that resistance of venous return, gravity siphon, negative pressure by centrifugal pump, and negative pressure applied to the air-purge line of the filter are balanced; that is, the venous return is sufficient, and the venous reservoir volume is kept stable. From this study we determined that this circuit design efficiently removes the entrained air in the venous line.

Air↗
PubMed2000

Omental flap for mediastinitis after median sternotomy in asplenia syndrome and gut malrotation.

We describe a 12-year-old patient with asplenia syndrome and gut malrotation who, after an interim step before a modified Fontan operation, developed life-threatening mediastinitis. A flap of the omentum arising from the transverse colon, longitudinally located in the left of the abdomen, was created and transferred to the mediastinum after a division of the arterial arcade at its most caudal extent. Her postoperative course was uneventful, and 12 months later, the modified Fontan operation was successfully completed. Although visceral heterotaxy results in an omental deformation, it does not preclude the use of an omental flap.

Abnormalities, Multiple↗
PubMed2000

Factors influencing arterial oxygenation early after bidirectional cavopulmonary shunt without additional sources of pulmonary blood flow.

OBJECTIVES: Although the arterial oxygen saturation after bidirectional cavopulmonary shunting should theoretically be homogeneous if additional pulmonary flow is obliterated, the arterial oxygen saturation has been found to vary in clinical practice. Knowledge of the preoperative and operative determinants of arterial oxygen saturation early after bidirectional cavopulmonary shunting may lead to a better understanding of this unique physiology. METHODS: Thirty-five patients who underwent bidirectional cavopulmonary shunting with obliteration of additional pulmonary flow were included in this study. The arterial oxygen saturation was determined at the 5 time points over a 48-hour period. Multivariable regression analysis was used to identify the independent predictors of the arterial oxygen saturation. RESULTS: No significant interval changes occurred in the arterial oxygen saturation during the 48 hours after bidirectional cavopulmonary shunting, which ranged from 61.6% to 95.6%. There was a significant inverse correlation between the postoperative superior vena cava pressure and the arterial oxygen saturation (P =.003). A low arterial oxygen saturation early after bidirectional cavopulmonary shunting was a predictor of mortality or exclusion from univentricular repair within 24 months (P =.012, odds ratio = 1.14). Of 11 factors identified by univariable analysis, multiple regression analysis indicated that age less than 8 months at the time of shunting (P <.0001) and ventricular volume overload (P =. 002) predicted a lower arterial oxygen saturation after bidirectional cavopulmonary shunting. CONCLUSIONS: Even without additional sources of pulmonary blood flow, several preoperative factors, including younger age and severe ventricular volume overload, predicted a decrease in the arterial oxygen saturation early after bidirectional cavopulmonary shunting. This, in turn, predicted poor outcome during 2 years of follow-up.

Adolescent↗
PubMed2000

New multilobe "accordion" flaps for three-dimensional reconstruction of wide, full-thickness defects in the oral floor.

When reconstructing a wide, full-thickness intraoral defect, the following principles are necessary for active food transport and improved swallowing and speech. First, the flap should touch the palate and obliterate the oral cavity. Second, jaw or flap excursion should not be hindered by tethering of the flap in the neck. And third, all surfaces of the tongue and oral floor, and the dead space of the floor should be reconstructed. To accomplish these goals, two new designs, similar to an accordion, using an anterolateral thigh flap and a deep inferior epigastric perforator flap have been developed. The outlines of multilobe flaps create an accordion-type structure of the tongue and oral floor complex. The advantages of the new designs using anterior thigh or deep inferior epigastric perforator flaps are follows: First, three-dimensional intraoral reconstitution allows maximal movement postoperatively of the reconstructed tongue. Second, the donor sites are so far from the tongue that simultaneous flap elevation is possible for tumor resectioning. Third, even in obese patients, totally or partially thin flaps are available. And fourth, in most patients the donor defects can be closed directly.

Adult↗
PubMed2000

Effect of external stenting and systemic hypertension on intimal hyperplasia in rat vein grafts.

OBJECTIVE: Overdistention of vein grafts in arterial circulation and systemic hypertension are thought to be influential risk factors contributing to vein graft failures. This study tested the effects of external stenting in preventing systemic hypertension and overdistention of the rat vein graft in the long term. METHODS: Jugular vein grafts were interposed into the carotid artery of normotensive (n = 39) and two-kidney, one-clip hypertensive (n = 30) rats. Jugular vein grafts wrapped with 1.5-mm-diameter polyester stents were used in normotensive (n = 26) and hypertensive (n = 25) rats. The vein grafts were harvested at 1, 2, 4, 8, 12, and 24 weeks after the grafting procedure. The neointimal area and wall thickness were measured by computerized planimetry, and Ki-67 immunohistochemistry was used to detect replicative smooth muscle cells in the graft wall. RESULTS: In each group, intimal hyperplasia was apparent at 1 week and increased gradually to 24 weeks. The number of Ki-67-positive cells was most increased at 2 weeks after the grafting procedure and gradually decreased thereafter. The numbers of Ki-67-positive cells and the extent of intimal hyperplasia were not significantly different between normotensive and hypertensive rats. Both neointima formation and cell proliferation in the graft wall were significantly reduced by external stenting as compared with the results with unstented grafts. CONCLUSION: Systemic hypertension by itself is not a risk factor for intimal hyperplasia and experimental vein graft failure in the long term. External stenting is effective against intimal hyperplasia, and it is possible to reduce the subsequent atherosclerotic change of the vein graft wall and improve the long-term patency of the vein graft with external stenting.

Animals↗
PubMed2000

Transmyocardial revascularization aggravates myocardial ischemia around the channels in the immediate phase.

We examined whether transmyocardial revascularization (TMR) relieves myocardial ischemia by increasing regional perfusion via the transmural channels in acute canine experiments. Regional blood flow during transient coronary ligation (2 min) was compared before and 30 min after TMR, and at the third transient ischemia the mid-left ventricle (LV) was cut and immediately frozen along the short axis for the analysis of NADH fluorescence in the regions around the TMR channels. In low-resolution analysis (2-4 g tissue or 2-3 cm(2) area), regional perfusion was not significantly altered after TMR, and NADH fluorescence was observed throughout the ischemic region without significant spatial variation. High-resolution analysis (2.8 mg, 1 mm x 1 mm) revealed that the flow after TMR was lower, and NADH fluorescence was higher in the regions close to the channels (1-2 mm) than in the regions 3-4 mm away from them. Creating TMR channels did not improve the regional perfusion and rather aggravated the local ischemia in the vicinity of the channels in the immediate phase.

Analysis of Variance↗
PubMed2000

Spinal atypical teratoid/rhabdoid tumor in an infant.

Atypical teratoid/rhabdoid tumor of the central nervous system in infancy and childhood was established as an entity based on histological, immunohistochemical, and cytogenetic studies. We report the case of a 7-month-old girl who presented with progressive paraplegia and hypesthesia of her legs. Imaging studies revealed a spinal cord mass occupying the entire spinal canal below the T(7) level. Through a T(12)-L(3) laminectomy, the intramedullary tumor was partially debulked. Histologically, the tumor specimen had rhabdoid cells, and immunostaining showed vimentin and cytokeratin positivity. No abnormality of chromosome 22q was detected with the fluorescence in situ hybridization method.

Biomarkers, Tumor↗
PubMed2000

Combined use of cellulose acetate polymer and retrievable platinum coils for the thrombosis of cervical carotid aneurysms.

Cellulose acetate polymer (CAP) solution is a new liquid embolic material, and it has been used clinically for the thrombosis of cerebral aneurysms. The purpose of the study was to test a method of aneurysm treatment. In an experimental model, retrievable interlocking detachable coils (IDCs) were used to create an intraaneurysmal frame or prop and then CAP was injected into 20 experimentally induced canine cervical aneurysms. Intraaneurysmal thrombosis was induced 1 week after aneurysm creation. Complete thrombosis was attempted in 12 aneurysms, and partial thrombosis was attempted in 4. Four other aneurysms served as controls. Follow-up angiography was performed for up to 8 weeks, and with the exception of 4 aneurysms, which were kept for a 2-year long-term follow-up study, the aneurysms were then harvested for histological examination. Thrombosis was successfully achieved in all cases except for 2 enlarged aneurysms that were initially partially thrombosed. No thromboembolism to distal vessels was observed. No compaction or shift of the CAP-IDC complex occurred even after 2 years. Histologically, CAP and IDCs conformed to the massive thrombotic complex without any fragmentation. By creating a frame or prop with retrievable microcoils, we were able to inject the CAP implies a comparison safely and precisely than has been previously reported. Our findings suggest that this method will be useful for the treatment of cerebral aneurysms.

Aneurysm↗