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Biomedical subjects

Kazuo Niwaya

Publications and source records attributed to Kazuo Niwaya.

At least 19 recordsLinked to original sources
PubMed2007

Is extracorporeal life support contraindicated in elderly patients?

BACKGROUND: Extracorporeal life support (ECLS) using percutaneous extracorporeal membrane oxygenation (ECMO) is now considered an important means of resuscitation for patients suffering from refractory cardiogenic shock. The indications for the use of ECLS have yet to be established, however, and its use for elderly patients is still controversial. We retrospectively evaluated the impact of ECLS on the survival of patients with cardiogenic shock to determine the validity of using ECLS in elderly patients (> or = 75 years of age). METHODS: Between 2000 and 2004, 91 patients were emergently placed on percutaneous ECMO. The patients were divided into two groups by age (group 1, n = 79: less than 75 years; group 2, n = 12: 75 years or older), which were compared for clinical outcome. Logistic regression analysis of the variables was performed to identify predictors of ability to be weaned from ECLS. RESULTS: Weaning from ECLS was achieved in 50 patients in group 1 (63.3%) and 6 patients in group 2 (50%; p = 0.37). Thirty-five patients in group 1 (44.3%) and 5 patients in group 2 (41.7%) were discharged from the hospital (p = 0.86). Logistic regression analysis revealed that patients with a body surface area of more than 1.50 m2, patients with cardiomyopathy, and patients who underwent interventions under ECMO support were more likely to be successfully supported by ECMO. CONCLUSIONS: Extracorporeal life support using percutaneous ECMO systems provides excellent cardiac support. It is also effective in resuscitating elderly patients, yielding hospital survival similar to that for younger patients.

Adolescent↗
PubMed2006

Graft design strategies with optimum antegrade bypass flow in total arterial off-pump coronary artery bypass.

OBJECTIVE: In arterial conduits, graft flow is one of the major determinants of long-term patency. We sought to delineate the effect of strategy for graft arrangement and design to three-vessel disease by evaluation of the dominant flow direction in each segment of a bypass graft. MATERIALS AND METHODS: We reviewed coronary angiograms of 1571 bypass grafts in 395 patients who underwent total arterial off-pump coronary revascularization without aortic manipulation for three-vessel disease since December 2000. The graft flow graded as A (antegrade), B (competitive), C (reverse), and O (no flow=occlusion). The current arrangement and design has been introduced since March 2003, and consists of the in-situ left internal thoracic artery (ITA) to the anterior descending artery and the composite I-graft of the right ITA and radial artery to the left circumflex (LCX) and right coronary artery (RCA) territories. Either clockwise or counterclockwise orientation, the I-graft was chosen to achieve a sufficient antegrade flow. Group I consisted of 181 patients with a single in-situ ITA as a composite Y-graft. Group II consisted of 214 patients with bilateral in-situ ITAs, which subdivided into Subgroup II-A consisted of 80 patients with bilateral in-situ ITAs until February 2003, and Subgroup II-B consisted of 134 patients with bilateral in-situ ITAs since March 2003. RESULTS: The number of distal anastomoses was 3.52+/-0.63 in Group I, and 4.36+/-0.83 in Group II, respectively (p<0.0001). The overall graft patency rate was 98.6% (1549/1571), and there was no significance different between the groups. The rate of grade A in Group II was 863/933 (92.5%) and was significantly higher (p=0.049) than that of Group I 572/638 (89.7%). The rate of functioning bypass in Subgroup II-B was (95.8%) 568/593, and was significantly higher (p=0.03) than that in Subgroup II-A (92.4%) 314/340. In Subgroup II-B, 233/268 (86.9%) of the conduits had completely grade A bypass flow, and this ratio was significantly higher (p=0.04) than that in Subgroup II-A (79.4%) 127/160. CONCLUSION: Usage of bilateral ITAs and selecting the orientation of the I-graft to LCX and RCA branches provide maximal distal anastomotic sites with satisfactory graft patency rate, and simultaneously minimized the incidence of reverse and competitive flow.

Aged↗
PubMed2006

Redo off-pump coronary bypass grafting with arterial grafts for Kawasaki disease.

Surgical revascularization for coronary artery lesions secondary to Kawasaki disease is relatively uncommon. The late stenosis of the saphenous vein graft is the problem to be solved. We report a case of redo off-pump coronary bypass grafting in a 35-year-old man, 20 years after bypass grafting using a saphenous vein graft. Off-pump total arterial revascularization was performed uneventfully. The procedure comprised grafting of bilateral internal thoracic arteries to left anterior descending branch and obtuse marginal branch, and radial artery to AV branch and posterior descending branch. Off-pump total arterial revascularization is a safe and less invasive procedure at the time of redo operation, even for patients with Kawasaki disease.

Adult↗
PubMed2006

The impact of mitral valve surgery combined with maze procedure.

OBJECTIVE: Recent studies indicated that successful maze procedure for atrial fibrillation (AF) adjunct to mitral valve surgery provided a lower incidence of stroke and recurrence of AF. The purpose of this study is to review the 13-year experience of these combined procedures and to identify the risk factors and late outcomes of successful maze procedures compared to failed maze procedures. METHODS: At a single institution, 521 consecutive patients underwent combined maze procedures with mitral valve replacements or valvuloplasties. Three kinds of maze techniques were primarily used: Cox-maze III, Kosakai maze, and cryo-maze procedure. Three months after the operation, 394 patients were in sinus rhythm (Group S) while the remaining 116 patients were in continuous or intermittent AF (Group F), excluding 11 early death patients. Risk factors for Group F were determined by the analysis of all patient demographics. Survival, freedom from stroke, cardiac events, and AF recurrence were analyzed. RESULTS: The proportion of the patients without any other simultaneous procedures was greater in Group S (41% vs 29%, P = 0.02). The distributions of mitral valve surgery and maze procedure techniques were similar in these two groups. A left atrium larger than 70 mm [hazard ratio (HR) = 2.6; 95% confidence interval range 1.04-6.3, P = 0.043], preoperative AF history longer than 10 years (HR = 8.2; 4.5-15.1, P < 0.001) and f-wave voltage in V1 smaller than 0.1 mV (HR = 6.2; 5.0-15.2, P < 0.001) were determined to be risk factors for unsuccessful maze procedures. All the results of Cox proportional hazards models showed superiority in Group S; actuarial survival rates (HR = 2.7; 1.04-7.0, P = 0.035), freedoms from stroke (HR = 3.0; 1.1-8.1, P = 0.003) and cardiac events (HR = 4.3; 2.9-6.1, P < 0.001). Freedom from AF recurrence rate was 98.4% at 5 years and 81.0% at 12 years in Group S, and 73.0% and 60.1% in overall patients. CONCLUSIONS: Patients with successful maze procedures resulted in higher survival rate, greater freedom from stroke and cardiac events. The large left atrium, small f-wave, and long AF duration were significant risk factors for failed maze procedures, suggesting that earlier surgical interventions would result in superior results in mitral valve surgery combined with maze procedure.

Adult↗
PubMed2006

Functional angiographic evaluation of individual, sequential, and composite arterial grafts.

BACKGROUND: To help optimize graft arrangement, we examined the effects of target vessel characteristics, conduit type, and interactions between the target vessels on the occurrence of flow reversal or occlusion. METHODS: The postoperative angiograms of 458 patients after total arterial revascularization with an off-pump, no aortic manipulation technique beginning in December 2000 were reviewed. Reverse flow was defined as the lack of opacification of a distal anastomotic site during graft angiography, but clear retrograde graft opacification during native coronary angiography. We analyzed characteristics of the target coronary branches, and bypass conduits. The potential interactions between coronary branches and sequential anastomoses were categorized as those with two 75% stenotic branches (situation 1); one 75% stenotic branch at the end of the graft and a 99% to 100% stenotic branch at the middle of the graft (situation 2); and a composite Y (or K) graft with one end to a 75% stenotic branch and the other to a 99% to 100% stenotic branch (situation 3). RESULTS: A total of 18 bypasses (1.1%) were occluded while reverse flow was found in 4.5% (74 of 1,627). In a multivariate analysis of the 521 bypass conduits having more than two distal anastomoses, the predictors of reverse flow or occlusion were a right coronary artery target with 75% or less stenosis (p = 0.006), more than three distal anastomoses with a conduit (p = 0.005), situation 1 (p = 0.04), situation 2 (p < 0.0001), and situation 3 (p < 0.0001). CONCLUSIONS: Interactions between coronary branches and graft arrangement play important roles in flow distribution. Graft arrangement should be adjusted for each patient to minimize reverse flow.

Aged↗
PubMed2006

Angiographic flow grading and graft arrangement of arterial conduits.

OBJECTIVE: We sought to delineate the effects of competitive and reverse flow on the intermediate-term patency of arterial conduits and examined graft arrangements for maximizing antegrade bypass flow. METHODS: The angiograms of 2083 bypass grafts in 570 patients who underwent off-pump total arterial revascularization without aortic manipulation since December 2000 were reviewed. The blood flow in the bypass grafts were graded A (antegrade), B (competitive), C (reverse), or O (occlusion). The mean number of distal anastomoses was 3.65 +/- 0.94 per patient. RESULTS: In the early angiography 91.3% (1901/2083) of the bypasses were grade A. Thirty (1.4%) bypasses were grade O, whereas 2.9% (61/2083) were grade B, and 4.4%(91/2083) were grade C. In the multivariate analysis the end-to-side anastomosis (P < .0001), 4 or more distal anastomoses of the conduit (P = .01), native coronary stenosis of less than 75% (P < .0001), and target branch location of the right coronary artery territory (P < .0001) and left circumflex artery territory (P = .02) significantly correlated with grade non-A. The patency rate in the late angiography of the bypasses graded B or C in the early angiography was 7 (28.0%) of 25, whereas that of the bypasses graded A was 164 (89.1%) of 184 (P < .0001). The actuarial graft patency rate of the bypasses graded A was 72.3% at 3 years and was significantly higher than that of the bypasses graded B or C (28.6% at 3 years after surgical intervention, P < .0001). CONCLUSIONS: The sufficient antegrade bypass flow had a favorable effect on the graft patency of arterial conduits. The graft arrangement should be adjusted for each patient so as to maximize the antegrade bypass flow and to confirm the advantage of arterial grafts.

Aged↗
PubMed2006

Off-pump coronary artery bypass grafting for acute myocardial infarction.

BACKGROUND: The aim of this study was to evaluate the surgical results of off-pump coronary artery bypass grafting (OPCAB) for patients with acute myocardial infarction (AMI) within 14 days of the infarction. METHODS AND RESULTS: From April 2000 to January 2005 among 841 patients who underwent OPCAB, 43 consecutive patients (5.1%) were examined. Mean age at operation was 69.5 years and mean time from the onset of AMI to surgery was 4.6 days. Seventeen patients (39.5%) had left main trunk disease. Three patients (7.0%) underwent OPCAB following unsuccessful percutaneous coronary intervention, and 1 patient (2.3%) underwent redo procedure 9 years after previous coronary artery bypass grafting (CABG). Six patients (14%) were admitted in cardiogenic shock. Intraaortic balloon pumping was inserted preoperatively in 20 patients (46.5%). The average maximum creatine kinase-myocardial band was 139+/-181 (U/L). The mean number of grafts was 3.2 and the rate of complete revascularization was 91%. Two of six patients with preoperative cardiogenic shock were converted to on-pump beating CABG due to ventricular arrythmia. The early graft patency rate was 98%. All patients survived except 2 with preoperative cardiogenic shock. CONCLUSIONS: OPCAB can be performed after AMI as a relatively low-risk procedure with an acceptable mortality rate, even within 14 days of the infarction.

Aged↗
PubMed2006

Long-term follow-up of transvenous defibrillation leads: high incidence of fracture in coaxial polyurethane lead.

BACKGROUND: As a result of longer follow-up after implantation of cardioverter defibrillators (ICD), fatigue of the leads has become a concern. The aim of this study was to determine the incidence and clinical presentation of ICD lead failures. METHODS AND RESULTS: The study population consisted of 241 patients with 249 ICD leads who underwent implantation of an ICD with a transvenous lead system. After device implantation, the patients were routinely followed up every 4 months. Five lead failures (2.0%) occurred as an oversensing of artifact during the follow-up period (2.6+/-2.1 years); 4 of those 5 patients received inappropriate shocks and 1 case of lead failure was identified in a patient with frequent episodes of non-sustained ventricular fibrillation. In particular, the right ventricular polyurethane transvenous lead in the Medtronic model 6936 failed in 4 (13%) of 31 cases. Percutaneous lead extraction was not available in all cases, so an additional ICD lead was inserted through the same site of the subclavian vein. CONCLUSIONS: Lead failures may occur 5 years after ICD implantation and polyurethane leads have an especially high incidence of failure. However, there were no follow-up parameters observed that predicted lead failures.

Adult↗
PubMed2005

Surgical treatment of aortic regurgitation due to Takayasu arteritis: long-term morbidity and mortality.

BACKGROUND: The goal of this retrospective study was to determine the late outcome of surgical treatment for aortic valve regurgitation due to Takayasu arteritis and correlate it with evidence of inflammation on pathological examination. METHODS AND RESULTS: Ninety consecutive patients who underwent surgery for aortic valve regurgitation due to Takayasu arteritis between 1979 and 2003 were studied. Intraoperative pathological specimens of the aortic wall from 69 patients were retrospectively examined for inflammation. Aortic valve replacement was performed in 63 patients (group A) and composite graft repair in 27 patients (group B). The aortic root diameter was 39.9+/-9.5 mm in group A and 54.4+/-13.6 mm in group B (P<0.0001). Preoperative steroid therapy was performed in 40 patients (44.4%). Hospital mortality was 4.8% (3/63) in group A and 7.4% (2/27) in group B. The overall 15-year survival rate was 76.1%. Detachment of the valve or graft occurred in 11.1% (7/63) of group A and in 3.7% (1/27) of group B patients (P=0.43). Late dilatation (>50 mm) of the residual ascending aorta occurred in 11.1% (7/63) of group A and in 3.7% (1/27) of group B patients (P=0.43). Active inflammation was confirmed in intraoperative pathological specimens of 10 patients, and detachment of the valve or graft occurred in 4 of these patients. Univariate analysis of background variables revealed active inflammation to be a risk factor for detachment (P=0.0001; risk ratio 55). CONCLUSIONS: Late dilatation of the ascending aorta after aortic valve replacement is a clinically important finding. Active inflammation could be related to valve or graft detachment.

Adult↗
PubMed2005

Late outcomes after isolated coronary artery bypass grafting for ischemic mitral regurgitation.

OBJECTIVES: Although ischemic mitral regurgitation (IMR) is one of the most important issues to determine therapeutic strategy for ischemic heart disease, long-term outcome after coronary artery bypass grafting (CABG) for IMR is still unclear. It is also controversial how patients who would benefit from mitral valve (MV) surgery in combination with CABG should be identified. The purpose of this study is to elucidate late outcomes after isolated CABG for moderate IMR and to assess the indication of combined MV surgery. METHODS: Two hundred and seventy-nine patients who had grade 2 or 3 IMR preoperatively and underwent isolated CABG between 1980 and 2002 in our institute were enrolled. Mitral regurgitation was assessed by 2-dimensional Doppler echocardiography and left ventriculography. Among them, 84 patients (30.1%) had left ventricular ejection fraction (LVEF) less than 30% and 186 patients (66.7%) had prior inferior myocardial infarction (MI). RESULTS: One hundred and twenty-nine patients (46.2%) remained grade 2 or greater MR early postoperatively. Actuarial survival and freedom from cardiac events, analyzed by the Kaplan-Meier method, were 90.9% and 87.7% at 1 year, 79.2% and 68.8% at 5 years, 54.9% and 49.1% at 10 years and 48.8% and 18.9% at 15 years. Independent predictive risk factors for cardiac events, analyzed by multivariate analysis using the Cox proportional hazard model, were grade 2 or greater MR which remained early postoperatively (p = 0.0002), LVEF < 30% preoperatively (p = 0.0006), no inferior MI preoperatively (p = 0.007) and no internal thoracic artery-left anterior descending artery graft (p = 0.049). More than a 15% decrease in LVEF at more than 3 years after the operation was seen despite patent bypass grafts in 17.2% of patients who received a late follow-up catheterization, although 41.4% of patients showed an increase or less than 5% decrease in LVEF during this period. CONCLUSION: Combined MV surgery with CABG for IMR should be considered in patients with poor LVEF or without prior inferior MI.

Aged↗
PubMed2005

Early results of off-pump coronary artery bypass grafting for patients on chronic renal dialysis.

OBJECTIVE: Renal dialysis is one of the independent risk factors for coronary artery bypass graft surgery. Off-pump coronary artery bypass grafting (OPCAB) may become a good option for these patients. In this study, early results as well as surgical techniques of OPCAB in dialysis patients were analyzed compared with non-dialysis patients. METHODS: Between July 1997 and December 2002, 471 consecutive patients who underwent OPCAB were enrolled in this study. Among them, 20 patients (4.2%) had received hemodialysis regularly for more than 3 months until the operation. Severity of coronary artery disease or clinical presentations had no significant difference, however, left ventricular function was significantly impaired in dialysis patients. RESULTS: The average number of anastomosis was 2.8 +/- 1.0 in the dialysis group and 3.2 +/- 1.0 in the non-dialysis group (p=0.056). Twelve patients (60.0%) received 3 or more bypass grafts in the dialysis group. Among them, 6 patients were revascularized only by in-situ or composite arterial conduits using bilateral internal thoracic arteries with or without the gastroepiploic artery. No patients required aortic clamping in the dialysis group. There was no mortality or morbidity in dialysis patients. Perioperaitve bleeding and mechanical ventilation time in the intensive care unit was similar in both groups. No dialysis patients required prolonged mechanical ventilation and hemodialysis from the beginning of the operation to extubation. CONCLUSION: The rationale for OPCAB for dialysis patients has been established. Total arterial revascularization without aortic clamping is applicable for dialysis patients who require multivessel bypass grafts.

Aged↗
PubMed2005

Coronary embolism and subsequent myocardial abscess complicating ventricular aneurysm and tachycardia.

A 62-year-old female experienced a ventricular aneurysm and tachycardia caused by coronary embolism from mitral valve endocarditis. The patient underwent endoventricular patch plasty and cryoablation concomitant with valve replacement and survived without any operative complications. Pathological examination suggested that abscess formation played an important role regarding the disruption of the ventricular wall and development of the ventricular aneurysm and tachycardia. In previous reports, a myocardial abscess caused by a septic embolism has only been diagnosed using postmortem examinations as colony growth around the capillary vessels in the myocardium. We considered that our operation was effective and feasible in such an occurrence.

Abscess↗
PubMed2005

Off-pump coronary artery bypass grafting using only arterial grafts in elderly patients.

BACKGROUND: This study aimed to elucidate the safety and feasibility of off-pump coronary artery bypass grafting with only arterial grafts for elderly patients. METHODS: Of 653 patients who underwent off-pump coronary artery bypass grafting from April 2000 to December 2003, 581 patients did so with only arterial grafts. The average age was 66.9 +/- 9.3 years. The patients were divided into the elder group E (75 years old or more: 111 cases) or the younger group Y (younger than 75 years old: 470 cases). The mean follow-up term was 21 +/- 12 months. RESULTS: Additive and logistic EuroSCOREs of group E were significantly higher than those of group Y (p < 0.0001). The number of bypass grafts was 3.3 +/- 0.9 in group E and 3.3 +/- 1.1 in group Y (p = 0.43). The proportion of total revascularization was 74% (82 of 111) in group E and 80% (377 of 470) in group Y (p = 0.15). The number of bilateral implementations of internal thoracic artery was 10 (9.0%) in group E and 196 (42%) in group Y (p < 0.0001). The graft patency rate was 98.7% in group E and 97.8% in group Y (p = 0.96). Hospital mortality was 2.7% (3 of 111) in group E and 0.2% (1 of 470) in group Y (p = 0.095). The causes of death were unrelated to cardiac events. Major adverse cardiac events occurred in 5 patients (5.1%) in group E and in 24 patients (5.6%) in group Y (p > 0.99). CONCLUSIONS: Off-pump coronary artery bypass grafting using only arterial grafts in elderly patients is as safe and feasible as in young patients.

Age Factors↗
PubMed2005

Impact of preoperative and postoperative atrial fibrillation on outcome after mitral valvuloplasty for nonischemic mitral regurgitation.

OBJECTIVE: We sought to determine the impact of preoperative or postoperative atrial fibrillation on survival, stroke, and cardiac function after mitral valvuloplasty for mitral regurgitation. METHODS: Between 1991 and 2003, 1026 patients with nonischemic/noncardiomyopathy mitral valve regurgitation underwent mitral valve plasty in 3 centers; 663 patients remained in sinus rhythm (group A), and 363 patients had atrial fibrillation or flutter preoperatively (group B) with concomitant maze procedures (group BM, n = 163) or without maze procedures (group BN, n = 200). RESULTS: Eight-year freedom from cardiovascular-related death was better in group A (99.3%) than group B (BM: 96.9%, BN: 81.6%) ( P < .001) and also better in group BM than group BN ( P = .007). The adjusted hazard ratio of group B versus group A for preoperative differences was 5.1 (95% confidence interval: 1.8-14.8). Eight-year freedom from stroke was better in group A (99.2%) than group B (BM: 98.2%, BN: 82.6%) ( P < .001) and also better in group BM than group BN ( P < .001). Patients with preoperative atrial fibrillation had larger left atria and left ventricular systolic dimensions. The adjunct maze procedure improved left ventricular systolic dimensions over mitral repair alone (group A vs B: P = .359; group BM vs BN: P = .001). CONCLUSION: Preoperative permanent/persistent atrial fibrillation was associated with a dilated left atrium and reduced left ventricular function in patients with mitral regurgitation. Including the maze procedure with mitral repair improved survival, late cardiac function, and freedom from late stroke.

Actuarial Analysis↗
PubMed2005

Mitral valve repair and cryo-Maze procedure in Ehlers-Danlos syndrome.

A 48-year-old man presented with typical features of Ehlers-Danlos syndrome, such as soft and hyperextensible skin, subcutaneous nodules, clubbed feet, and a mild degree of pigeon chest. In addition, his past history revealed congenital dislocation of the hip joint, retinal detachment, and repeated episodes of congestive heart failure due to severe mitral regurgitation and atrial fibrillation. We subjected the patient to surgical repair of the mitral valve combined with the maze procedure, which proved successful.

Atrial Fibrillation↗
PubMed2005

Successful excision of a cystic tumor of the atrioventricular nodal region.

Cystic tumor of the atrioventricular nodal region is a rare cardiac primary tumor that can cause heart blockage and sudden death. Antemortem diagnosis and successful excision of the atrioventricular nodal region are extremely rare. A 45-year-old woman who presented with palpitations is reported. Electrocardiography revealed first-degree atrioventricular block. Echocardiography, computed tomography, and magnetic resonance imaging scans revealed a cystic mass attached to the interatrial septum. Complete surgical excision of the mass was achieved, although placement of a permanent pacemaker was required for complete heart blockage. Histopathological examination revealed the mass to be a cystic tumor of the atrioventricular nodal region. A 5-year follow-up has revealed no sign of recurrence.

Atrioventricular Node↗