Biomedical subjects

Kazuhiro Ohkura

Publications and source records attributed to Kazuhiro Ohkura.

12 recordsLinked to original sources

PubMed2005

Experimental study on the protective effects of edaravone against ischemic spinal cord injury.

OBJECTIVE: Reactive free radical species are thought to be involved in ischemic spinal cord injury. We investigated the effects of edaravone (Mitsubishi Pharma Co, Tokyo, Japan), a free radical scavenger, on spinal ischemia-reperfusion injury in a rabbit model. We also sought to estimate free radicals in the spinal cord using the microdialysis method. METHODS: Spinal cord ischemia was induced in New Zealand White rabbits. The animals were then divided into 4 groups. In the first experiment, which was carried out in group A (non-edaravone treated) and group B (edaravone treated), we assessed neurologic function and evaluated spinal cord histopathology. In the second experiment, which was performed in group C (non-edaravone treated) and group D (edaravone treated), we sequentially estimated the level of free radical species in the spinal cord with the microdialysis method. RESULTS: In the first experiment group B showed better neurologic function than group A. The number of viable neurons in the spinal cord gray matter was also higher in group B than in group A. The second experiment revealed that the level of free radical species was lower in group D at 75, 90, and 150 minutes after the beginning of reperfusion compared with levels seen in group C. The appearance of free radical species in the latter group was found to have a biphasic pattern, with peaks at 75 and 150 minutes after the beginning of reperfusion. CONCLUSION: Edaravone exerted a significant protective effect on the spinal cord against ischemia-reperfusion injury by suppressing the level of free radical species, which was demonstrated with the microdialysis method.

Animals↗

PubMed2004

Surgical experience of full root replacement with freestyle bioprosthesis: indications, surgical technique, and results.

PURPOSE: We examined the postoperative clinical results and hemodynamic performance of full root replacement using a freestyle stentless bioprosthesis performed in patients with severe aortic stenosis or aortic root disease. METHODS: We performed 17 full root replacements with a stentless bioprosthesis. The mean age of the patients was 73.9 +/- 4.1 years, ranging from 63 to 81, and 35% were male. The operative indications were aortic stenosis (AS) in 9 patients, aortic stenosis with regurgitation (ASR) in 4, and aortic regurgitation due to aortic root dissection or annuloaortic ectasia in 4. RESULTS: The valve size of the freestyle bioprosthesis was 25.1 +/- 2.6 mm, ranging from 21 to 29 mm. There were no early or late mortalities. No postoperative aortic regurgitation was found. In the 13 patients undergoing an operation for AS or ASR, peak pressure gradients were 8.5 +/- 4.2 and 8.4 +/- 5.2 mmHg, and LV mass indices were 159.4 +/- 19.0 and 106.9 +/- 22.6 g/m(2), as determined by echocardiography at 1 and 10 months after operation, respectively. CONCLUSION: Full root replacement with stentless bioprosthesis is a suitable procedure for patients of advanced age with severe AS, aortic root dissection, or annuloaortic ectasia, because of its superior hemodynamics.

Aged↗

PubMed2004

Repair of delayed left ventricular rupture after mitral valve replacement: report of a case.

Rupture of the left ventricle (LV) after mitral valve replacement (MVR) is a devastating complication, associated with high mortality. A 64-year-old woman with a type I delayed LV rupture, which occurred after MVR with a 27-mm St. Jude Medical mitral prosthesis for mitral stenosis, was successfully treated by a combination of intracardiac and extracardiac surgical repair techniques. The extracardiac repair involved approximating the edges of myocardium around the tear with large sutures bolstered by strips of Teflon felt, then covering the epicardial hematoma with another porcine pericardial patch, using gelatin resorcinol formaldehyde glue and collagen sheets. The intracardiac repair involved suturing the edges of an oval piece of porcine pericardium to the endocardium around the laceration. No LV pseudoaneurysm was detected postoperatively on echocardiography or computed tomography scans. The patient is well 2 years after the operation.

Bioprosthesis↗

PubMed2004

Separate grafts or en bloc anastomosis for arch vessels reimplantation to the aortic arch.

BACKGROUND: This study compares the results of the separated graft technique and the en bloc technique as a method of arch vessels reimplantation during surgery of the aortic arch and determines the predictive risk factors associated with hospital mortality and adverse neurologic outcome during aortic arch repair. METHODS: Between October 1995 and March 2002, 352 patients (mean age 64.9 +/- 11.3 years; urgent status: 49/352 [13.9%]) underwent surgery of the aortic arch using the separated graft technique (group A: n = 230 [65.3%]) and the en bloc technique (group B: n = 122 [34.7%]) to reimplant the arch vessels. An aortic arch replacement was performed in 32 patients (9.1%), an ascending aorta and arch replacement in 222 patients (53.1%), an aortic arch and descending aorta replacement in 16 patients (4.5%), and a complete replacement of the thoracic aorta in 82 patients (23.3%). Brain protection was achieved by means of antegrade selective cerebral perfusion in all patients. The mean cardiopulmonary bypass time was 204.8 +/- 61.9 minutes (group A: 199.7 +/- 57.0 minutes; group B: 214.5 +/- 69.4 minutes; p = 0.033), the mean myocardial ischemic time was 121.5 +/- 43.2 minutes (group A: 116.7 +/- 38.9 minutes; group B: 130.80 +/- 49.4 minutes; p = 0.003), and the mean antegrade selective cerebral perfusion time was 84.5 +/- 36.4 (group A: separated graft technique 91.3 +/- 36.3 minutes; group B: 70.6 +/- 32.7 minutes; p = 0.000). RESULTS: Overall hospital mortality was 6.8% (group A: 6.5%; group B: 7.4%; p = not significant [NS]). The permanent neurologic dysfunction rate was 3.5% (group A: 4.0%; group B: 2.5%; p = NS). The transient neurologic dysfunction rate was 5.4% (group A: 5.5%; group B: 5.2%, p = NS). Postoperative systemic morbidity was similar in the two groups. A logistic regression analysis revealed preoperative cardiac tamponade (p = 0.011; odds ratio [OR] = 5.9) and cardiopulmonary bypass time (p = 0.010; OR = 1.01/min) to be independent predictors of hospital mortality. None of the analyzed preoperative variables were associated with an increased risk of permanent neurologic dysfunction. Age more than 70 years old (p = 0.029, OR = 5.7), myocardial revascularization (p = 0.001, OR = 2.9), and pump time (p = 0.013, OR = 1.01/min) were indicated as independent predictors of transient neurologic dysfunction by logistic regression. CONCLUSIONS: Antegrade selective cerebral perfusion was confirmed to be a safe method of cerebral protection allowing complex aortic arch operations to be performed with acceptable results in terms of hospital mortality and neurologic outcome. The separated graft technique had no adverse impact on hospital mortality and morbidity.

Adult↗

PubMed2004

Comparison of pH management during antegrade selective cerebral perfusion in canine models with old cerebral infarction.

OBJECTIVE: We sought to examine the influence on the brain, with or without old infarction, of pH management during antegrade selective cerebral perfusion in a canine model. METHODS: A cerebral infarct canine model was created by injecting a cylindrical silicone embolus. Dogs that had obvious neurologic deficits and had survived for 4 weeks or more were included in the model. Deep hypothermia with antegrade selective cerebral perfusion was performed in intact mongrel dogs (alpha-stat: group A, n = 6; pH-stat: group B, n = 6) and mongrel dogs with infarctions (alpha-stat: group C, n = 6; pH-stat: group D, n = 6). Maxillary vein saturation of oxygen, venous-arterial lactate difference, and serum concentrations of malondialdehyde and glutamate were measured and central conduction times and amplitude in somatosensory evoked potentials were assessed during the operation. RESULTS: During the experimental procedure, the maxillary vein saturation of oxygen was significantly less (P <.05), whereas the venous-arterial lactate difference was significantly greater (P <.05) in the cooling phase to 28 degrees C in group C than in the other groups. The pH-stat group showed significantly greater arterial Paco(2) and lower pH than the alpha-stat group during the period between the cooling to 28 degrees C and the rewarming to 28 degrees C (P <.05). Other intraoperative parameters did not show any difference among the groups. In group C the serum concentrations of malondialdehyde and glutamate significantly increased, as did the central conduction time, whereas in both groups C and D the amplitude ratio decreased significantly. CONCLUSIONS: This experiment suggests that pH-stat management during antegrade selective cerebral perfusion provides more effective protection for a brain with old infarction than alpha-stat management.

Animals↗

PubMed2003

Late reoperation for proximal aortic and arch complications after previous composite graft replacement in Marfan patients.

BACKGROUND: Marfan patients who received composite graft replacement for proximal aortic disease frequently require late reoperation. The initial surgical technique for this lesion remains controversial. METHODS: Fourteen Marfan patients who received composite graft replacement for annuloaortic ectasia with or without aortic dissection required late reoperation thorough re-median sternotomy. The techniques used for an initial composite graft replacement were the original Bentall procedure in 11 patients, the Cabrol procedure in 2, and coronary button technique in 1. Reoperation was indicated for prosthesis-related complications in 10 patients, distal aortic lesion in 13, or for both lesions in 8. Reoperations were performed, on average, 8.4 years after an initial operation. Reoperative procedures included re-composite graft replacement in 1 patient, total arch replacement in 5, and re-composite graft replacement with total arch replacement in 8. RESULTS: There were two in-hospital deaths (14.3%). Although pseudoaneurysms of the coronary artery or distal aorta occurred in the original Bentall or Cabrol procedures, true aneurysms of the coronary artery were noted even in the coronary button technique. Six patients required a total of eight subsequent descending or thoracoabdominal aortic replacements for an aneurysmal formation of a distal false lumen. CONCLUSIONS: The coronary button technique, with a small side hole for coronary anastomosis, is the procedure of choice for annuloaortic ectasia because it reduces the risk of coronary artery-related complications. Concomitant total arch replacement may be recommended for annuloaortic ectasia with DeBakey type I aortic dissection in selected patients to avoid the risk of reoperation on the aortic arch.

Adult↗

PubMed2003

Brain protection using antegrade selective cerebral perfusion: a multicenter study.

BACKGROUND: To evaluate the results of antegrade selective cerebral perfusion as a method of brain protection during surgery of the thoracic aorta and to determine predictors of hospital mortality and adverse neurologic outcome. METHODS: Between October 1995 and March 2002, 588 patients underwent aortic surgery with the aid of antegrade selective cerebral perfusion. There were 334 men (56.8%); the mean age was 63.7 +/- 11.8 years. One hundred sixty-two patients (27.6%) underwent urgent operation. The separated graft technique was employed to reimplant the arch vessels in 230 patients (65.3%) of the 352 requiring aortic arch replacement. Associated procedures were performed in 254 patients (43.2%). One hundred twelve patients underwent elephant trunk procedure. The mean cerebral perfusion time was 67 +/- 37 minutes. RESULTS: The overall hospital mortality rate was 8.7%. A logistic regression analysis revealed urgent operation, recent central neurologic event, tamponade, unplanned coronary artery revascularization and pump time to be independent predictors of hospital mortality (p < 0.05). The permanent neurologic dysfunction rate was 3.8%. A logistic regression analysis showed tamponade to be independent predictor of permanent neurologic dysfunction (p < 0.05). The transient neurologic dysfunction rate was 5.6%. Recent central neurologic event, tamponade, coronary disease, and aortic valve replacement were indicated as independent predictors of transient neurologic dysfunction by logistic regression (p < 0.05). CONCLUSIONS: In our experience the utilization of antegrade selective cerebral perfusion resulted in encouraging results in terms of hospital mortality and brain complications. Neither the extent of the replacement nor the duration of the cerebral perfusion had an impact on hospital mortality and neurologic outcome.

Aorta, Thoracic↗

PubMed2002

Aortic root replacement using a homograft for recurrent valve endocarditis.

Prosthetic valve endocarditis is a relatively rare condition associated with high mortality. Endocarditis affecting 2 successive mechanical valves at the aortic position has not, to the best of our knowledge, been described. We reported such a patient whose condition was further complicated by mitral regurgitation, pulmonary hypertension, worsening heart failure, and cardiac conduction abnormalities. Considering the failure of 2 previous mechanical valves, we conducted a homograft replacement of the aortic root with coronary reattachment. Mitral regurgitation was treated by annuloplasty. The patient's early postoperative course was uneventful and he was doing well 16 months after surgery. We discuss the overall treatment strategy for recurrent prosthetic valve endocarditis and potential homograft advantages.

Adult↗

PubMed2002

Total and subtotal aortic replacement for extensive aortic dissection in patients with or without Marfan's syndrome.

OBJECTIVES: Extensive aortic dissection with multiple entries often found in Marfan's syndrome patients ultimately requires replacement of the whole aorta. We present a surgical strategy and results for total and subtotal aortic replacement. METHODS: Subjects were 18 patients, including 14 Marfan's patients undergoing total (n = 13) or subtotal (excluding aortic arch) aortic replacement (n = 5), for DeBakey type I aortic dissection (n = 13) and DeBakey type IIIb aortic dissection with annuloaortic ectasia (n = 5) between February 1991 and April 2001. Mean age was 39.9 +/- 0.8 years--34.9 +/- 6.6 years in Marfan's patients vs. 57.7 +/- 4.7 years in non-Marfan patients. All operations were staged, with the mean number required per patient 3.1 +/- 0.8. RESULTS: Early mortality was 0% and late mortality 11% (2 of 18). Paraplegia or paraparesis occurring in 11%. Except for these patients, all current survivors enjoy good quality of life. CONCLUSIONS: Total and subtotal aortic replacement for extensive aortic dissection may decrease mortality due to rupture or associated disease.

Adult↗

PubMed2002

Surgical outcome of acute type A aortic dissection: analysis of risk factors.

BACKGROUND: The aim of this study was to assess the risk factors for the early and late outcome of the surgical treatment of acute type A aortic dissection. METHODS: From 1983 to 2000, a total of 130 patients underwent operation for acute type A aortic dissection. Extent of distal aortic resection included ascending aorta in 19 patients (15%), hemiarch in 29 (22%), and total arch in 82 (63%). In all, 31 preoperative and perioperative variables were analyzed using univariate and multiple logistic regression models for independent predictors of in-hospital mortality and risk of late reoperation. After excluding in-hospital deaths, risk factors for late death were analyzed by Cox proportional hazard analysis. RESULTS: In-hospital mortality was 19.2% (25 of 130 patients). Multivariable analysis indicated that renal/mesenteric ischemia and shock were independent predictors of in-hospital death. At 10 years, the actuarial survival rate including in-hospital mortality was 70.9% +/- 4.7%, and the reoperation event-free rate was 73.5% +/- 5.7%. Aortic valve resuspension was an independent predictor of proximal aortic reoperation, whereas nonresection of intimal tear and younger age were independent predictors for distal aortic reoperation. Chronic obstructive pulmonary disease was the only independent predictor for late death. CONCLUSIONS: Patients' preoperative dissection-related complications and comorbidities significantly affect early and late survival rates after surgical treatment of acute type A aortic dissection.

Acute Disease↗

PubMed2002

Usefulness of antegrade selective cerebral perfusion during aortic arch operations.

BACKGROUND: To evaluate the safety and usefulness of antegrade selective cerebral perfusion (SCP) during arch aneurysm or aortic dissection operations. METHODS: Between January 1986 and December 2001, 330 patients underwent aortic arch repair using SCP. Operations were performed with the aid of hypothermic extracorporeal circulation, SCP, and systemic circulatory arrest in most cases. In all, 89 patients (27%) were operated on for acute aortic dissection, 77 (23%) for chronic aortic dissection, and 164 (50%) for degenerative aneurysm. Total arch replacement using a branched graft was performed in 288 patients (94%). Mean SCP time was 86.2 +/- 28.5 minutes. RESULTS: The overall in-hospital mortality rate was 11.2% (falling to 3.2% in the 124 patients operated on between 1997 and 2001). Independent determinants of hospital mortality were pump time, renal/mesenteric ischemia, chronic renal failure, increasing age, period of operation, and nonuse of four-branched arch graft. The overall postoperative incidences of temporary and permanent neurologic dysfunction were 4.2% and 2.4%, respectively. There was no significant correlation between SCP time and in-hospital mortality or neurologic outcome. CONCLUSIONS: Selective cerebral perfusion is a reliable technique for cerebral protection and it facilitates complex and time-consuming total arch replacement.

Adolescent↗

PubMed2002

Impact of an aggressive surgical approach on surgical outcome in type A aortic dissection.

BACKGROUND: To evaluate the impact of an aggressive surgical approach on early and late outcome in type A aortic dissection. METHODS: From 1983 to 2001, 240 patients underwent operation for acute (n = 138) and chronic (n = 102) type A aortic dissection. The extent of distal aortic resection included the ascending aorta in 39 (16%) patients, hemiarch (HAR) in 47 (20%), and total arch (TAR) in 154 (64%), including 19 patients who also had their descending aorta replaced (DAR). RESULTS: The in-hospital mortality did not differ between TAR with or without DAR and other more conservative techniques (12.3% versus 16.3%). Actuarial survival at 10 years including in-hospital mortality was 72.4% +/- 3.3% and freedom from reoperation was 77.2% +/- 3.6% for all patients: neither was influenced by the extent of distal aortic resection or acuity of aortic dissection. Multivariate analysis revealed younger age and failure to resect the intimal tear to be independent determinants for late reoperation. However, in contrast to 22 patients who had more conservative operations, none of the patients with TAR required reoperation on the aortic arch through a sternotomy incision. CONCLUSIONS: An aggressive surgical approach did not adversely influence early and late survival following type A aortic dissection; it reduced the necessity of late reoperation and facilitated distal aortic reoperation.

Adult↗