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Biomedical subjects

Akihiko Usui

Publications and source records attributed to Akihiko Usui.

At least 19 recordsLinked to original sources
PubMed2006

Mitral valve motion assessed by high-speed video camera in isolated swine heart.

OBJECTIVE: We have recently reported our isolated and working swine heart model that examines the valve motion precisely by a high-speed digital video camera system. Using this modality, the present study aimed (1) to delineate the motion of the mitral leaflets, chords and annulus throughout the cardiac cycle, and (2) to elucidate the influence of alterations in loading conditions on leaflet excursion. METHODS: The valve motion of five isolated and working swine hearts was observed by an endoscope recording the images at 250 frames per second. Modified Krebs-Ringer solution was used as the sole perfusate. The images were obtained in hearts 30 min after reperfusion, changing the left atrial pressure as 4, 8, and 12 mmHg. RESULTS: The motion of the mitral valve in the vicinity of diastole was considered to be well understood by dividing the entire sequence into five stages: 'decoaptation,' 'E excursion,' 'diastasis,' 'A excursion,' and 'coaptation.' Initial separation occurred at both sides of the central tips of the leaflets. The leading edges always followed the mid-portion of the rough zone during opening and closing. The 'strut' second-order chords retained their tension throughout the cardiac cycle and played the role as rotary shafts of the other branching chords. The first-order chords lost their tension during opening, suggesting they mainly are involved in valve competence. Annular constriction occurred coincident with atrial contraction. An increase in preload made the isovolumic relaxation and contraction times shorter. The leaflets opened faster in the rapid-filling phase, whereas they required more time for opening and closing in the atrial-filling phase. CONCLUSIONS: The present study revealed the integrated movement of the mitral leaflets, chords and annulus, as well as the impact of altered preload.

Animals↗
PubMed2006

Returning reservoir blood to right atrium during extracorporeal circulation for descending aortic surgery.

We report our techniques on conducting a closed-circuit femoral-femoral bypass during descending aortic surgery by which collected blood can be easily returned into the right atrium. The main circuit was composed of a centrifugal pump, an artificial membrane lung, and a filter. A reservoir with a roller pump was connected to the main circuit via a filter. Extracorporeal circulation was established by right atrial drainage via the femoral vein and femoral arterial return. On aortic cross-clamping, systemic blood pressure was controlled by activating the roller pump in reverse rotation and shifting the body blood into the reservoir temporarily. For a small amount of bleeding after aortotomy, the reservoir blood was returned via the femoral artery by activating the roller pump in normal rotation. When a large amount of bleeding was present making the systemic blood pressure fall, the main circuit was clamped just distal to the centrifugal pump and reservoir blood was directly returned to the right atrium to maintain systemic pressure. Confirming that bleeding was reduced, the clamp distal to the centrifugal pump was gradually released and blood was delivered to both the right atrium and the femoral artery. We believe that our system is a highly beneficial modality.

Aged↗
PubMed2006

A vascular tube for intercostal artery reimplantation.

Paraplegia and paraparesis are major concerns in descending and thoracoabdominal aortic repair. A shorter period of spinal cord ischemia is preferred for protection. We have developed a new technique in which plural intercostal arteries are reattached in a short time. The lower descending aorta is tailored using automatic sutures, and a vascular tube is made with diameter about 2.0 cm. Blood supply of intercostal arteries including the Adamkiewicz artery is resumed by perfusing the vascular tube in not more than 20 min. This technique has been applied in four patients, and there was neither paraplegia nor paraparesis.

Aortic Dissection↗
PubMed2006

Surgical treatment for thoracic aortic aneurysm with aberrant right subclavian artery.

We present two operative cases of thoracic aortic aneurysm combined with aberrant right subclavian artery (ARSA). Case 1 was a 71-year-old man with a fusiform-type arch aneurysm. He underwent total aortic arch replacement to reconstruct all 4 arch branches. Case 2 was a 39-year-old man suffering from chronic DeBakey type IIIb dissection. He underwent total descending thoracic aortic replacement for the remaining ARSA. In both cases ARSA was diagnosed preoperatively by reconstructed three-dimensional computed tomography (3D-CT). Both patients followed uneventful postoperative courses with excellent results. 3D-CT is helpful for precise planning of surgical strategy in such cases.

Adult↗
PubMed2006

Infective endocarditis with an aortic periannular abscess extending along the right coronary artery.

A 50-year-old male underwent surgery for infective aortic valve endocarditis, which had been refractory to medical treatment. The valve was bicuspid, and involvement of the annular and subannular structures was recognized. A large suppurative discharge was obtained on incising this portion. Although there was no interventricular shunt, the abscess cavity was revealed to extend through the epicardial surface of the right atrioventricular groove. Following extensive debridement and irrigation, the defect was closed by an autologous pericardial patch. A 23 mm mechanical valve was implanted placing some of the stitches deep into the muscular interventricular septum. Infection was controlled by six-week administration of cefazolin sodium and gentamicin sulfate, and the patient survived.

Abscess↗
PubMed2006

Midterm results for endovascular stent grafts via median sternotomy for distal aortic arch aneurysm.

Dislocation or perigraft leakage is a major problem during the follow-up period for endovascular stent graft (EVG) implantation via median sternotomy for distal aortic arch aneurysm. Anchoring sutures have been applied for the prevention of these complications. Here, we evaluate the midterm results and the efficacy of anchoring sutures. There were 21 male and 2 female patients enrolled in the study with an average age of 70 years (59-83). Aneurysm types were 21 true aneurysms (13 fusiform, 8 saccular), 1 chronic dissection, and 1 penetrating aortic ulcer. Total arch replacement was performed in two patients and aortocoronary bypass grafting was combined in four patients. Anchoring sutures to fix the EVG via median sternotomy were applied for 11 recent patients. The average follow-up period was 44 (22-79) months. There were no operative mortalities, but one case of paraplegia, one of stroke, and two of temporary spinal cord dysfunction. Complications related to EVG via median sternotomy occurred in five patients who had not received anchoring sutures, but the 11 patients with anchoring sutures showed no EVG-related complications. A chronic type B dissection revealed impending rupture due to false lumen infection 1 year after operation and repeat surgery was performed. Stent dislocation occurred in four patients, two of whom required repeat surgery via left thoracotomy due to endoleakage 3 and 4 years after surgery. One died from aneurismal rupture 5 years after surgery. One required emergency graft replacement because of graft perforation 5 years after surgery. The proportion of patients free from EVG-related events at 5 years after surgery was 75%. Anchoring sutures (P = 0.0155) and a large aneurysm of more than 80 mm (P = 0.0190) were predictors of late EVG-related complications. There were five late deaths: two were from stroke, one from rupture, one from cancer, and one from multiple organ failure after repeat surgery. EVG shortens postoperative recovery with relatively lower mortality, but spinal cord injury is a complication occurring with a relatively high rate. Patients with large aneurysms are not good candidates for EVG implantation via median sternotomy Anchoring sutures to fix the EVG to the aortic wall should help prevent EVG-related events and improve the durability of EVG.

Aged↗
PubMed2006

Development of a novel temporary epicardial pacing wire with biodegradable film.

PURPOSE: A temporary epicardial pacing wire (TEPW) has been routinely placed in patients undergoing cardiac surgery. However, its fixation or removal occasionally causes troublesome complications. The aim of this study is to develop a novel TEPW using biodegradable film to fix the electrode to the epicardium without needle stabbing. DESCRIPTION: A biodegradable film was prepared with poly(L-lactide-co-epsilon-caprolactone). The film has a honeycomb-patterned structure that serves as a temporary adhesive for the myocardial surface, and the electrode was incorporated within the film. The novel TEPW was placed on the ventricular epicardium of dogs (group A, n = 5). As a control, conventional TEPW was inserted (group B, n = 6). The pacing threshold, R wave amplitude, impedance, and slew rate were measured at postoperative days 0, 1, 3, 5, 7, and 14, and complications after removal were checked. EVALUATION: All measurements in both groups were identified and differences were not observed. In addition, the novel TEPWs could be easily removed without related complications. CONCLUSIONS: This novel TEPW is safe and feasible for postoperative management of cardiac surgeries.

Absorbable Implants↗
PubMed2006

Late mortality and morbidity in elderly patients with mechanical heart valves.

A retrospective study was performed in patients under and over 65 years old implanted with a mechanical valve, to compare late mortality and morbidity. Of 381 patients who underwent mechanical valve replacement at Nagoya University in the 1990s, 357 (11 hospital deaths and 13 lost to follow-up; 96.4% follow-up rate) were followed up for 7.9 +/- 3.3 years (2,811 patient-years). They were divided into two groups either side of 65 years of age at operation. The young and elderly patient groups contained 275 and 82 patients, respectively. The survival rate in the young group was 96.1% (95% confidence interval, 93.7%-98.5%) at 5 years and 92.0% (95% confidence interval, 88.3%-95.7%) at 10 years, which was significantly better than 88.0% (95% confidence interval, 80.6%-95.4%) at 5 years and 73.8% (95% confidence interval, 66.2%-85.4%) at 10 years in the elderly group. The two groups did not differ significantly in the incidence of thromboembolic events, bleeding events, endocarditis, or reoperation. We are also encouraged by the fact that mechanical valves are not a risk factor for late mortality or morbidity, even in elderly patients.

Age Factors↗
PubMed2006

Mitral valve surgery for dilated cardiomyopathy with mitral regurgitation.

Outcomes of surgery for non-ischemic non-valvular dilated cardiomyopathy with associated mitral regurgitation were assessed in 8 consecutive patients who underwent 9 mitral valve operations between 2001 and 2004. Mitral valve replacement was performed when the coaptation depth exceeded 10 mm. Two patients initially underwent mitral valvuloplasty, and 6 underwent valve replacement. One patient had valve replacement soon after valvuloplasty. Transthoracic echocardiography was performed immediately before surgery, before discharge, and during follow-up. Transesophageal echocardiography was carried out intraoperatively to assess valvular and ventricular function. Postoperative mean functional class was significantly better than the preoperative value (2.4 +/- 0.7 vs. 3.3 +/- 0.7), and the improvement was sustained during follow-up (2.0 +/- 0.7). The ejection fraction and left ventricular end-diastolic dimension did not improve. One patient died without leaving hospital and two died during follow-up. The 2- and 4-year survival rates were 75.0% and 37.5%. Mitral valve surgery improved functional class without obvious changes in ejection fraction or left ventricular end-diastolic dimension.

Adult↗
PubMed2006

Clinical protocol for angiogenesis by intramyocardial injection of autologous bone marrow mononuclear cells in patients with severe coronary artery disease: TACT-NAGOYA-HEART.

BACKGROUND: Despite recent improvements in the treatments of coronary artery disease (CAD), there are a considerable number of patients who can not receive complete revascularization because of severe or total arterial occlusion. Intramyocardial injection of autologous bone marrow mononuclear cells (ABMMCs) has been shown to induce neovascularization of ischemic myocardium. METHODS AND RESULTS: The study will investigate the safety and feasibility of intramyocardial injections of ABMMCs and test the hypothesis that this treatment would promote neovascularization and improve left ventricular (LV) global and/or regional function in patients with severe CAD who have no other option. ABMMCs (approximately 10(6) cells) will be injected into the area of ischemic myocardium where the coronary artery is not graftable, in combination with bypass surgery to the other coronary branches. Myocardial perfusion and LV global and regional function will be evaluated, based on the micromanometer-tipped catheter method, single-photon emission tomography, and myocardial enhanced and color tissue Doppler echocardiography at baseline and during 12 month follow-up. CONCLUSIONS: This project will demonstrate that intramyocardial injection of ABMMCs with or without coronary artery bypass surgery could be a safe and effective method for therapeutic neovascularization, resulting in an improvement of cardiac function in patients with severe CAD.

Bone Marrow Cells↗
PubMed2006

Measurement of cerebral-oxygenation status when commencing cardiopulmonary bypass in pediatric open-heart surgery.

OBJECTIVE: We hypothesize that there is a difference in the cerebral-oxygenation status between cyanotic and non-cyanotic congenital heart disease when commencing a crystalloid-primed cardiopulmonary bypass (CPB). We tested this hypothesis by using near-infrared spectroscopy (NIRS). METHODS: Group 1 consisted of ten patients with non-cyanotic congenital heart diseases, including atrial septal (n=4) and ventricular septal defects (n=6), while group 2 consisted of ten patients with cyanotic congenital heart diseases, including tetralogy of Fallot (n=7) and univentricular heart (n=3). Changes in cerebral-oxygenated, deoxygenated and total hemoglobin concentrations were measured by NIRS just before and every minute for the first 10 min after commencing CPB. Arterial blood analysis was performed at those same time times. RESULTS: NIRS showed a rapid fall and plateauing of cerebral-oxygenated, deoxygenated and total hemoglobin in group 1. However, although group 2 showed a rapid fall and plateauing of cerebral-oxygenated hemoglobin, a rapid fall and continuous gradual decrease in cerebral-deoxygenated and total hemoglobin were also seen. Cerebral-deoxygenated and total hemoglobin decreased more markedly in group 2 than in group 1 (P<0.001, 0.01, respectively). CONCLUSION: NIRS revealed that the cerebral-oxygenated hemoglobin could be maintained at a similar level at the beginning of CPB in both groups. However, it showed a different distribution of cerebral-deoxygenated and total hemoglobin between the groups. An inadequate cerebral-oxygenation status may occur in the early phase of CPB in patients with cyanotic congenital heart diseases.

Analysis of Variance↗
PubMed2005

Surgery for calcific aortic root stenosis in homozygous familial hypercholesterolemia.

A 35-year-old female with homozygous familial hyperlipidemia (IIa) was referred to our hospital for an operation against supravalvular and valvular aortic stenosis. She had been treated with low-density lipoprotein apheresis for 20 years, and total cholesterol ranged between 200 and 400 mg/dl under this treatment. She had undergone percutaneous coronary intervention for ostial stenosis of the right coronary artery three times since the age of 19. Unenhanced three-dimensional computed tomography showed supravalvular stenosis, funnelling and heavily calcified aorta. An operation was performed under deep hypothermic circulatory arrest without aortic cross clamping. After the ascending aorta had been replaced with a one-branched vascular graft, arterial perfusion was resumed. The stenosed ascending aorta was resected at the sinotubular junction. Because the aortic root was still extremely small, the noncoronary sinus and the commissure between left and right coronary cusp were incised, and the aortic root was enlarged with linguiform vascular-graft patches. A 21-mm mechanical valve was implanted. The postoperative course was uneventful.

Adult↗
PubMed2005

Early clinical results of St. Jude Medical Symmetry aortic connector.

An automated anastomosis device named St. Jude Medical symmetry aortic connector has been used worldwide for off-pump coronary artery bypass grafting. However, early graft obstruction was recently reported, and its predictors should be clarified. From April 2002 to March 2004, 38 patients in our institution underwent off-pump coronary artery bypass grafting using the St. Jude Medical Symmetry aortic connector for saphenous vein graft (SVG) procedures; measurement of intraoperative graft flow and postoperative coronary angiography was performed. Early SVG events occurred in 9 (24%) patients: 8 occlusion cases and 1 case of stenosis. Predictors of early SVG events were assessed from a comparative study. Univariate logistic regression identified hyperlipidemia as the only significant predictor of early SVG events (P = 0.02, odds ratio 7.78). Lower SVG flow rate and poor ejection fraction did not show statistical significance (P = 0.09, odds ratio 1.09 and P = 0.09, odds ratio 0.96). The SVG event rate was much higher for the left circumflex branch compared with other locations (31% vs. 9%, P = 0.03) and decreased with increasing aortic connector size (small, 32%; median, 14%; large, 0%). Multivariate analysis did not identify a predictor of SVG events. The aortic connector is associated with a high incidence of early SVG events. Patients should be cautiously selected and the procedure should not be used for left anterior descending coronary artery or culprit lesions.

Aged↗
PubMed2005

Thoracic aneurysm rupture due to graft perforation after endovascular stent-grafting via median sternotomy.

We performed emergency repeat surgery for aneurismal rupture due to graft perforation with mechanical stress of the Z stent in a kinking graft after frozen elephant trunk procedure. Graft kinking occurred due to cranial migration of the Z stent. It is important to prevent stent dislodgement in order to achieve long-term durability and reliability in the frozen elephant trunk procedure.

Aged↗
PubMed2005

Arch-first technique performed under hypothermic circulatory arrest with retrograde cerebral perfusion improves neurological outcomes for total arch replacement.

OBJECTIVE: From 1998, we have adopted the arch first technique (reconstruction of arch vessels first and distal anastomosis second) instead of the distal anastomosis first technique for total arch replacement. The aim is to reduce the period of deep hypothermic circulatory arrest and the retrograde cerebral perfusion time. We evaluate the surgical results of the arch first technique. METHODS: The arch first technique was used in 50 cases (38 male and 12 female), of average age 68 years, from 1998 to 2003. There were 33 true aneurysms and 10 chronic and seven acute type A dissections. Clinical results were evaluated and compared with the distal first technique used in 24 cases operated on between 1992 and 1998. These were 14 males and 10 females, with an average age of 68 years. There were 16 true aneurysms, and three chronic and five acute aortic dissections. RESULTS: For the arch first technique there is a significantly shorter circulatory arrest time (32 vs. 72min, P<0.0001), but similar body ischemic times (76 vs. 72min, N.S.). With the arch first technique, all but two patients awoke within 24h, with an average delay of 9.3h. In the distal first technique, two patients did not awaken and three patients showed delayed awakening, with an average awakening time of 24h. The arch first technique led to one hospital death (2%), due to residual aneurysm rupture. Reversible ischemic neurological deficit (RIND) was complicated in three cases (6%), but no stroke occurred during operation. In the distal first technique there were four strokes, one RIND and three hospital deaths (12.5%). The arch first technique gave a significantly lower intra-operative stroke rate (P=0.0030) and smaller hospital mortality (P=0.0615). The arch first technique led to five late deaths, with an 84.5% 3 year survival rate, and the distal first technique led to six late deaths with a 59.1% 3-year survival rate. CONCLUSIONS: The arch first technique is clearly superior to the conventional distal first technique in surgical mortality and morbidity regarding neurological outcome, and provides a higher survival rate and better quality of life. The arch first technique is an excellent method for total arch replacement.

Adult↗