Biomedical subjects

Soichiro Kitamura

Publications and source records attributed to Soichiro Kitamura.

123 records · Page 7Linked to original sources

PubMed2002

Total arch replacement with elephant trunk procedure for retrograde dissection.

BACKGROUND: The surgical management of type A dissection with the intimal tear in the descending aorta--retrograde dissection--has some challenging aspects because the standard approach through a median sternotomy for ascending aortic dissection is difficult in these cases in which the intimal tear is located in the descending aorta. METHODS: From January 1995 to December 2001, 12 (8.6%) consecutive patients aged 40 to 71 years underwent total arch replacement with an elephant trunk procedure through a median sternotomy for retrograde dissection of the ascending aorta (acute: 10, chronic: 2) among 139 patients with type A dissection. The intimal tear was located in the descending aorta in all patients. Dissection extended proximally to the aortic root in 7 patients and to the ascending aorta in 5, and extended distally to the abdominal aorta in 4 and to the common iliac artery in 8. RESULTS: Hospital mortality occurred in 1 patient (8%) owing to multiple organ failure after malperfusion of the renal arteries. Postoperatively the false lumen in the descending aorta was closed in all patients who survived but the false lumen in the abdominal aorta was patent in 9. The thoracic and abdominal aorta had slight dilatation in 2 patients. CONCLUSIONS: These data suggest that total arch replacement with an elephant trunk procedure through a median sternomy should be recommended in patients with type A dissection and the intimal tear in the descending aorta. This procedure induces thrombosis of the remaining false lumen in the distal aorta postoperatively.

Adult↗

PubMed2002

Impact of Cox maze procedure on outcome in patients with atrial fibrillation and mitral valve disease.

OBJECTIVE: We sought to determine whether the Cox maze procedure provides additional benefit to patients with atrial fibrillation undergoing mitral valve operations. METHODS: Between May 1992 and August 2000, we performed 258 Cox maze procedures with mitral valve replacement (n = 147) or mitral valve repair (n = 111). We compared the outcomes of these patients with those of 61 control patients with preoperative atrial fibrillation who underwent mitral valve replacement alone during the same interval. The three cohorts were similar in age, sex, and proportion of patients in preoperative New York Heart Association functional class 3 or 4. RESULTS: Although 5-year survivals were similar among the groups (94% for mitral valve replacement alone, 95% for mitral valve replacement plus maze, and 97% for mitral valve repair plus maze), freedoms from atrial fibrillation at 5 years were significantly higher in the mitral valve replacement plus maze group (78%) and the mitral valve repair plus maze group (81%) than in the mitral valve replacement group (6%, P <.0001). Freedoms from stroke at 5 years were 97% for the mitral valve replacement plus maze group, 97% for the mitral valve repair plus maze group, and only 79% for mitral valve replacement group (P <.0001). Multivariable analysis with Cox hazard model revealed that the most significant risk factor for late stroke was the omission of the Cox maze procedure (P =.003). CONCLUSIONS: The addition of the Cox maze procedure to mitral valve repair and replacement was safe and effective for selected patients. Elimination of atrial fibrillation significantly decreased the incidence of late stroke.

Aged↗

PubMed2002

The role of coronary bypass operation on children with Kawasaki disease.

BACKGROUND: Kawasaki disease, initially called mucocutaneous lymph node syndrome was reported 35 years ago as a new inflammatory disease in infants and children and is characterized by a variety of symptoms and signs resulted from systemic vasculitis. Although the etiology of the disease remains unknown, its serious coronary complications have been proved to cause ischemic heart disease in children, and are now the most common cause of pediatric coronary disease in the world. The incidence of serious coronary sequelae is fortunately low (2-3% of patients with Kawasaki disease), but once myocardial infarction occurs in children, the mortality is quite high (22% at the first infarction). Development of surgical treatment for the disease was essential in preventing premature death and improving the quality of life of children. METHODS AND RESULTS: Coronary revascularization surgery was attempted following careful evaluation of characteristic patters of coronary aneurysms and obstructions secondary to Kawasaki disease, although the surgical efficacy was initially questioned because the disease is inflammatory vasculitis in origin. The operation utilizing the pedicled internal thoracic artery has been demonstrated quite successful and now established as a reliable treatment for inflammatory coronary obstructions due to Kawasaki disease (the Kitamura Operation). There is valid evidence for the internal thoracic artery graft being a viable structure, accommodating in length and diameter for the growth of children. Results of the surgery and long-term prognosis are favorable and postoperative quality of life is markedly improved. CONCLUSIONS: Coronary bypass operation utilizing the pedicled internal thoracic artery is a safe and reliable surgical modality for coronary artery sequelae in children due to Kawasaki disease. Long-term follow-up results up to 20-years are quite satisfactory.

Adolescent↗

PubMed2002

Trends in the clinical and morphological characteristics of cardiac myxoma: 20-year experience of a single tertiary referral center in Japan.

The purpose of this study was to clarify whether or not a change in the clinical characteristics of cardiac myxoma has occurred during the past 2 decades. The clinical records of 57 patients (22 men, 35 women; age, 52+/-14 years) with myxoma that had been surgically treated between May 1978 and July 1997 at the National Cardiovascular Center in Japan were reviewed. All myxomas were discovered by transthoracic echocardiography. They were divided into an early group (n=30) treated in the first decade (1978-1987) and a late group (n=27) treated in the second decade (1988-1997). The incidence of myxoma, patient characteristics, preoperative symptoms and echocardiographic features did not differ between the 2 groups. In contrast, the maximal dimensions of myxoma in the early group were significantly larger than those in the late group (6.3 +/-2.7 cm vs 4.3+/-1.3 cm, p=0.012). The weight of myxoma in the early group tended to be heavier than that in the late group (76+/-80 g vs 25+/-18 g, p=0.054). The incidence of patients with asymptomatic myxoma also tended to increase in the late group (7% vs 26%, p=0.07). Although there was no difference in the incidence of myxoma, smaller and asymptomatic myxomas were more frequent during the last decade, probably as a result of the development of cardiac imaging, particularly echocardiography.

Adult↗

PubMed2002

Perioperative advantages of off-pump coronary artery bypass grafting.

For the first time in Japan, off-pump coronary artery bypass grafting (OPCAB) was compared with the conventional on-pump technique, retrospectively examining the morbidity associated with coronary artery bypass grafting (CABG) and assessing the efficacy of OPCAB. In 2000, 158 patients underwent CABG: 95 patients (60%) had OPCAB (Group I) and 63 patients (40%) had conventional CABG (Group II). The operating time, length of intensive care unit (ICU) stay, ventilation time, postoperative bleeding, transfusion, postoperative renal function, occurrence of stroke, and early graft patency were examined in both groups. There were no hospital deaths in either group. The operating time, ICU stay, and ventilation time were significantly (p < 0.0001, p = 0.013, and p < 0.0001, respectively) shorter in Group I (351 +/- 85 min, 3.0 +/- 1.4 days, and 5.1 +/- 2.8h) than in Group II (449 +/- 112 min, 3.6 +/- 1.8 days, and 13.7 +/- 18.0 h). The postoperative blood loss within 12h and the transfusion volume were significantly (p = 0.0004 and p < 0.0001, respectively) smaller in Group I (480 +/- 210 ml and 300 +/- 490ml) than in Group II (720 +/- 430ml and 1,230 +/- 1,180 ml). Peak serum blood urea nitrogen and creatinine concentrations (excluding patients with preoperative chronic renal failure, ie a preoperative serum creatinine > 1.5 mg/dl) were significantly (p < 0.0001 and p < 0.0001, respectively) lower in Group I (16.2 +/- 15.2mg/dl and 0.81 +/- 0.72 mg/dl) than in Group II (19.2 +/- 7.6 mg/dl and 0.92 +/- 0.28 mg/dl). There were no perioperative strokes in Group I, but 6.4% of Group II patients suffered a stroke. There was no significant difference in graft patency between the groups (95.6% vs 94.9%). OPCAB reduced the mortality and morbidity of coronary revascularization, with a shorter operating time and more rapid recovery from surgery.

Aged↗

PubMed2002

Total arterial off-pump coronary revascularization with only internal thoracic artery and composite radial artery grafts.

OBJECTIVE: Total arterial off-pump coronary artery bypass (OPCAB) grafting with only internal thoracic artery (ITA) and composite radial artery (RA) grafts has been applied extensively to avoid cerebral complications and late vein graft failure. We evaluated the initial experience with this method by clinical and angiographic study. METHODS: Between April 2000 and May 2002, 257 patients underwent OPCAB grafting with this technique. The range of ages at operation was 42 to 86 years (mean, 66.1 +/- 8.6 years). On average, 3.28 +/- 0.86 grafts per patient were completed. More than 4 distal anastomoses were performed in 88 patients (34%). For coronary revascularization, 289 ITA and 555 RA grafts were used. The RA was used as a Y graft in 211 patients, as an I graft (for ITA extension) in 52 patients, and as a K graft (the side of the RA attached to the side of the left ITA) in 28 patients. Sequential bypass grafting was performed with 190 RA and 7 ITA grafts. The sites of distal anastomoses were 256 left anterior descending arteries (30%), 236 posterolateral branches (28%), 144 posterior descending arteries (17%), 106 diagonal branches (13%), 82 obtuse marginal branches (10%), and 19 right coronary arteries (2%). RESULTS: There were 1 operative death (0.4%) due to cerebral hemorrhage and 2 episodes of stroke (0.8%) during postoperative angiography. There were no clinical underperfusion syndromes or new intra-aortic balloon pump insertions. Perioperative myocardial infarction occurred in 12 patients (4.7%), sternal dehiscence in 5 (1.9%), and early coronary intervention in 4 (1.6%). There was no deep wound infection, reexploration for bleeding, or hand ischemia. The actuarial survival rate and the cardiac event-free rate at 2 years were 98.6% +/- 2.4% and 94.2% +/- 0.8%, respectively. Early postoperative angiography revealed a 97.8% (264/270) graft patency of ITAs and 97.9% (512/523) graft patency of RAs in 238 patients. Flow competition of the RA graft was recognized in 22 patients and, as indicated by follow-up angiographic study, did not cause late graft occlusion. CONCLUSIONS: OPCAB grafting with ITAs and composite RAs provides excellent early and intermediate clinical results and graft patency.

Adult↗

PubMed2002

[Heart transplantation for dilated cardiomyopathy possibly caused by fulminant acute myocarditis: a case report].

A 13-year-old boy [corrected] underwent heart transplantation for severe congestive heart failure due to dilated cardiomyopathy possibly caused by fulminant acute myocarditis. He suddenly suffered chest discomfort and loss of consciousness during running, and was referred to a hospital with cardiogenic shock. Electrocardiography showed ventricular tachycardia and echocardiography revealed severe hypokinesis in an extensive area of the left ventricular wall with markedly decreased left ventricular ejection fraction. Percutaneous cardiopulmonary support, intraaortic balloon pumping and artificial respiration were performed. He suffered from severe heart failure with septic shock and bleeding tendency. A left ventricular assist system was fitted at 73 days after onset, and he was transferred to the National Cardiovascular Center on the 119th hospital day. At 319 days after the left ventricular assist system operation, heart transplantation was performed. The etiology and treatment for severe heart failure, and several social problems which occurred during care for heart transplantation are discussed.

Acute Disease↗

PubMed2002

Eight-year experience of combined valve repair for mitral regurgitation and maze procedure.

BACKGROUND AND AIMS OF THE STUDY: Although atrial fibrillation (AF) is often associated with severe mitral regurgitation (MR), a simultaneous maze procedure for AF associated with repair of MR remains controversial. In this study, mid-term results of combined mitral valve repair and the maze procedure were examined. METHODS: Between May 1992 and April 2001, 85 patients (61 males, 24 females) underwent valve repair for MR and the maze procedure. Mean age at surgery was 61.8+/-9.1 years; mean follow up was 4.7+/-2.3 years. Valve lesions were anterior in 26 patients (31%), posterior in 31 (36%), anterior + posterior in 23 (27%), and simple dilated annulus in five (6%). Chordal replacement with expanded PTFE sutures was performed in 40 patients (47%), and leaflet resection in 41 (48%). Ring annuloplasty was also applied in 61 patients (72%). Associated procedures were tricuspid valve annuloplasty in 33 (36%), coronary artery bypass grafting in four, atrial septal defect closure in two, aortic valve repair in one, and resection of abnormal septum in the left atrium in one. RESULTS: There was one hospital death (1%), and one late death (1%). Reopening the chest for bleeding was necessary in six cases (7%). One thromboembolic episode was detected during follow up (0.25%/patient-year). Reoperation for MR was performed in three patients (4%). Actuarial event-free survival rate was 90.0+/-6.4% at eight years. Sinus rhythm was regained in 68 patients (81%), and atrial A-wave was detected in 57 (68%) by pulsed Doppler study. Postoperative left ventricular diastolic and systolic dimensions were significantly (p = 0.001 and p = 0.017) smaller in patients who restored sinus rhythm than in those who did not (48.6+/-4.6 versus 54.6+/-4.7 mm, and 33.0+/-6.0 versus 38.1+/-6.9 mm). CONCLUSION: Combined mitral valve repair for MR and the maze procedure showed satisfactory midterm results. Postoperative sinus rhythm conversion by the maze procedure may reduce left ventricular size, and the incidence of thromboembolic episodes in mitral valve repair.

Adult↗

PubMed2002

Multiple off-pump coronary revascularization with "aorta no-touch " technique using composite and sequential methods.

BACKGROUND: Although off-pump coronary artery bypass grafting (OPCAB) has been widely applied in patients who are considered high risk for cardiopulmonary bypass (CPB), there is still a risk of stroke during the operation because of the ascending aortic partial clamp for proximal anastomosis. In the present study, we report the initial results of an "aorta no-touch " technique using an in-situ graft and composite and sequential grafting methods. METHODS: Between March 2000 and April 2001, 120 patients underwent OPCAB with this technique. The age of patients ranged from 47 to 86 years, with a mean age of 65.7 +/- 8.7 years. On average, 3.12 +/- 0.77 grafts per patient were completed. More than 4 distal anastomoses were performed in 32 patients (27%). As in-situ grafts, 140 internal thoracic arteries (ITAs) and 9 gastroepiploic arteries were used. The radial artery (RA) was used as a Y composite graft in 91 patients, as an I composite graft in 25, and as a K composite graft in 2. Sequential bypass grafting was performed using the RA in 60 patients, the saphenous vein (SV) in 6, the ITA in 4, and the gastroepiploic artery (GEA) in 3. Arterial grafts were used in 92% (345/374) of total bypass grafts. Distal anastomosed sites were 119 left anterior descending arteries (LADs) (32%), 90 posterolateral branches (24%), 64 posterior descending arteries (17%), 49 diagonal branches (13%), 39 obtuse marginal branches (10%), and 13 right coronary arteries (3.5%). RESULTS: There was no operative death or stroke. Early postoperative angiography revealed 95.5% (321/336) graft patency with 100% patency (119/119) of ITA to LAD grafts. Graft patency of the ITAs and RAs (98.5% and 95.9%) were significantly better than that of the GEA (79.0%, p = 0.0064 and p = 0.030) and saphenous vein (82.3%, p = 0.011 and p = 0.048). CONCLUSION: OPCAB performed with the aorta no-touch technique using an in-situ graft and composite and sequential grafting methods provides excellent early clinical results and graft patency.

Aged↗

PubMed2002

Effect of maze procedure in patients with atrial fibrillation undergoing valve replacement.

BACKGROUND AND AIMS OF THE STUDY: The study aim was to elucidate the impact of the maze procedure on late outcome after valve replacement. METHODS: Between 1992 and 2000, 241 patients underwent the maze procedure combined with valve replacement. Patients were allocated to three groups: aortic valve replacement (AVR/maze, n = 16); mitral valve replacement (MVR/maze, n = 148); and combined aortic and mitral valve replacement (DVR/maze, n = 77). RESULTS: Mean follow up was 3.9 +/- 2.3 years. Hospital mortality was 0% in the AVR/maze group, 2.0% (n = 3) in the MVR/maze group, and 3.9% (n = 3) in the DVR/maze group. Elimination of atrial fibrillation (AF) at discharge was achieved in 74.3-75.9% of cases. Freedom from recurrence of AF/atrial flutter was 71.2% in the AVR/maze group, 68.2% in the MVR/maze group, and 64.0% in the DVR/maze group at five-year follow up. By multivariate analysis, risk factors for recurrence of AF/atrial flutter included preoperative enlarged left atrial dimension >70 mm, decreased postoperative fractional shortening <30%, and absence of postoperative left atrial contraction. Freedom from stroke was 93.6% in patients who achieved regular rhythm (normal sinus rhythm or junctional rhythm), and 80.9% in those with recurrence of AF at five years after surgery (p = 0.03). CONCLUSION: The combined maze procedure and valve replacement is safe and effective in selected patients. Restoration of regular rhythm significantly reduced the incidence of late stroke.

Adult↗

PubMedDate not supplied

Partial left ventriculectomy--The Third International Registry Report 2002.

BACKGROUND: An international registry of partial left ventriculectomy (PLV) has been expanded, updated, and refined to include 440 cases voluntarily reported from 51 hospitals in 11 countries. RESULTS: Gender, age, ventricular dimension, etiology, ethnology, myocardial mass, operative variation or presence or absence of mitral regurgitation as well as transplant indication had no effects on event-free survival, which was defined as either absence of death or ventricular failure requiring ventricular assist device or listing for transplantation. Preoperative patient condition such as NYHA functional class IV, depressed contractility, and decompensation requiring an emergency procedure were associated with reduced event-free survival. Other risk factors included early date of surgery, lack of experience, and extended myocardial resection. Performance of PLV reached a peak by 1998 and was largely abandoned by 2000 except in Asia, where experienced institutes continue to perform PLV in patients in better condition with preserved myocardial contractility. CONCLUSION: Avoidance of delineated risk factors appears to improve recent survival and may help stratify high- or low-risk patients for PLV. An integrated approach with mechanical and biological circulatory assist may improve prognosis for patients with dilated failing hearts. While frequency of PLV has decreased, the concept of ventricular volume reduction has been extended to other volume reduction procedures and less invasive procedures now under clinical trial.

Adolescent↗

PubMedDate not supplied

Observation of cavitation in a mechanical heart valve in a total artificial heart.

Recently, cavitation on the surface of mechanical heart valves has been studied as a cause of fractures occurring in implanted mechanical heart valves. The cause of cavitation in mechanical heart valves was investigated using the 25 mm Medtronic Hall valve and the 23 mm Omnicarbon valve. Closing of these valves in the mitral position was simulated in an electrohydraulic totally artificial heart. Tests were conducted under physiologic pressures at heart rates from 60 to 100 beats per minute with cardiac outputs from 4.8 to 7.7 L/min. The disk closing motion was measured by a laser displacement sensor. A high-speed video camera was used to observe the cavitation bubbles in the mechanical heart valves. The maximum closing velocity of the Omnicarbon valve was faster than that of the Medtronic Hall valve. In both valves, the closing velocity of the leaflet, used as the cavitation threshold, was approximately 1.3-1.5 m/s. In the case of the Medtronic Hall valve, cavitation bubbles were generated by the squeeze flow and by the effects of the venturi and the water hammer. With the Omnicarbon valve, the cavitation bubbles were generated by the squeeze flow and the water hammer. The mechanism leading to the development of cavitation bubbles depended on the valve closing velocity and the valve stop geometry. Most of the cavitation bubbles were observed around the valve stop and were generated by the squeeze flow.

Biomechanical Phenomena↗

PubMedDate not supplied

Three-dimensional cardiac tissue engineering using a thermoresponsive artificial extracellular matrix.

The purpose of this study was to try to reconstitute three-dimensional cardiac tissue using a thermoresponsive artificial extracellular matrix, poly (N-isopropylacrylamide)-grafted gelatin (PNIPAM-gelatin), as the scaffold. PNIPAM-gelatin solution gels almost immediately when heated above 34 degrees C. We thought this property could become advantageous as scaffolding for reconstituting three-dimensional tissue. Because PNIPAM-gelatin solution gels so quickly, all seeded cells in PNIPAM-gelatin solution would become entrapped and uniformly distributed toward three dimensions. Thus it would be possible to reconstitute three-dimensional tissue by a very simple method of mixing cells and PNIPAM-gelatin solution. Fetal rat cardiac cells were mixed with PNIPAM-gelatin solution, incubated at 37 degrees C to allow the mixture to gel, and cultured in vitro. To define suitable culture conditions the following parameters were tested: (1) PNIPAM-gelatin concentration, 0.04 approximately 0.125 mg/ml; (2) cell seeding density, 1 approximately 50 x 10(6) cells/ml; and (3) addition or not of hyaluronic acid. With a PNIPAM-gelatin concentration of 0.05 mg/ml, a cell seeding density of 50 x 10(6) cells/ml, and the addition of hyaluronic acid, tissue was reconstituted and it contracted synchronously. After hematoxylin and eosin staining, the cells reconstituted three-dimensional tissue, and the tissue cross-section was approximately 60 microm thick.

Acrylic Resins↗

PubMedDate not supplied

Mechanisms of mechanical heart valve cavitation in an electrohydraulic total artificial heart.

Until now, we have estimated cavitation for mechanical heart valves (MHV) mounted in an electrohydraulic total artificial heart (EHTAH) with tap water as a working fluid. However, tap water at room temperature is not a proper substitute for blood at 37 degrees C. We therefore investigated MHV cavitation using a glycerin solution that was identical in viscosity and vapor pressure to blood at body temperature. In this study, six different kinds of monoleaflet and bileaflet valves were mounted in the mitral position in an EHTAH, and we investigated the mechanisms for MHV cavitation. The valve closing velocity, pressure drop measurements, and a high-speed video camera were used to investigate the mechanism for MHV cavitation and to select the best MHV for our EHTAH. The closing velocity of the bileaflet valves was slower than that of the monoleaflet valves. Cavitation bubbles were concentrated on the edge of the valve stop and along the leaflet tip. It was established that squeeze flow holds the key to MHV cavitation in our study. Cavitation intensity increased with an increase in the valve closing velocity and the valve stop area. With regard to squeeze flow, the Björk-Shiley valve, because it is associated with slow squeeze flow, and the bileaflet valve with low valve closing velocity and small valve stop areas are better able to prevent blood cell damage than the monoleaflet valves.

Heart Valve Prosthesis↗

PubMedDate not supplied

Left ventricular volume reduction surgery: The 4th International Registry Report 2004.

BACKGROUND AND METHODS: An international registry of left ventricular volume reduction (LVVR) procedures, including partial left ventriculectomy, has been expanded, updated, and refined to include 568 cases voluntarily reported from 52 hospitals in 12 countries. RESULTS: Gender, age, ventricular dimension, ethnology, myocardial mass, presence or absence of mitral regurgitation, as well as transplant indication, had little effect on event-free survival, which was defined as either absence of death or ventricular failure requiring mechanical assist or transplantation. Poor preoperative patient condition such as New York Heart Association classification IV, depressed contractility and decompensation requiring an emergency procedure were associated with reduced event-free survival. Other risk factors included an early surgery date, lack of experience, dilated cardiomyopathy as the underlying pathology and extended myocardial resection. Performance of LVVR reached a peak by 1998, but was largely abandoned by 2001, except in Asia, where experienced institutes continue to perform it in patients in better condition with preserved myocardial contractility. CONCLUSION: Avoidance of risk factors appears to have contributed to the recent survival improvement and may help stratify patients for LVVR. While performance has been decreasing, the concept has been extended to other LVVR and less invasive procedures, which are now under clinical trials.

Adolescent↗