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Dive into the research topics where Nobuchika Ozaki is active.

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Featured researches published by Nobuchika Ozaki.


The Journal of Thoracic and Cardiovascular Surgery | 1999

Long-term evaluation of treatment for functional tricuspid regurgitation with regurgitant volume: characteristic differences based on primary cardiac lesion

Takaki Sugimoto; Masayoshi Okada; Nobuchika Ozaki; Tadashi Hatakeyama; Toshihiro Kawahira

OBJECTIVES The aim of this study was to characterize differences in the long-term effects of treatment for functional tricuspid regurgitation based on the primary cardiac lesion. METHODS Ninety-six patients with valvular heart disease and 32 patients with atrial septal defects associated with tricuspid regurgitation were studied. The tricuspid annular diameter was associated with evidence of right heart failure. In valvular heart disease, a Kay annuloplasty was performed in 33 patients with a tricuspid annular diameter of >/=40 mm to 44 mm, a modified De Vega annuloplasty in 12 patients with a tricuspid annular diameter of >/=45 mm to 49 mm, and a modified De Vega annuloplasty, annuloplasty using a Carpentier ring, or tricuspid valve replacement in each of 4 patients with a tricuspid annular diameter of >/=50 mm. In atrial septal defects, a Kay annuloplasty was performed in 11 patients with a tricuspid annular diameter of >/=45 mm to 49 mm, and a modified De Vega annuloplasty was performed in 5 patients with a tricuspid annular diameter of >/=50 mm. A mean follow-up period was 79 months after operation. RESULTS In the patients with a tricuspid annular diameter of <50 mm, the hemodynamic and clinical findings and tricuspid regurgitation remarkably improved. In the patients with valvular heart disease with a tricuspid annular diameter of >/=50 mm, however, the right heart parameters also showed improvement but less so when compared with those patients with a tricuspid annular diameter of <50 mm. In addition, 4 patients undergoing a modified De Vega annuloplasty have had a gradual increase in tricuspid regurgitation and clinical manifestations late after the operation. In contrast, all 5 patients with atrial septal defects with a tricuspid annular diameter of >/=50 mm have shown remarkable improvement, similar to those with a tricuspid annular diameter of <50 mm. Preoperative analyses revealed that the right heart function in atrial septal defects had not deteriorated to the same extent as in valvular heart disease. CONCLUSION In the patients with a severely dilated tricuspid anulus (>/=50 mm), the postoperative change of tricuspid regurgitation differed between those patients with valvular heart disease and atrial septal defects.


Journal of Vascular Surgery | 2003

Transbrachial arterial insertion of aortic occlusion balloon catheter in patients with shock from ruptured abdominal aortic aneurysm.

Hitoshi Matsuda; Yosuke Tanaka; Yutaka Hino; Ritsu Matsukawa; Nobuchika Ozaki; Kenji Okada; Takuro Tsukube; Yoshihiko Tsuji; Yutaka Okita

OBJECTIVE Of 125 surgical patients with abdominal aortic aneurysm (AAA) treated from 1999, 11 patients with deep shock from ruptured AAAs who underwent aortic occlusion balloon catheter (AOBC) insertion before laparotomy were studied. METHODS With the patients under local anesthesia, the brachial artery was exposed and the balloon catheter was inserted into the thoracic aorta. The balloon was inflated halfway and pulled back gently to the orifice of the left subclavian artery, and was advanced with the aid of blood flow down to the abdominal aorta. After full inflation of the balloon, the catheter was pulled until the balloon was fixed at the proximal shoulder of the AAA. RESULTS AOBC insertion was completed within 16.1 +/- 5.1 minutes. Systolic blood pressure at presentation was 84.1 +/- 31.7 mm Hg, deteriorated to 60.9 +/- 15.4 mm Hg on arrival in the operating room, and increased significantly (P <.0001) to 123.4 +/- 25.3 mm Hg after AOBC insertion. The balloon burst in three patients. Embolic complications were observed in two patients. There were three deaths, two associated with the balloon bursting. In nine patients whose shock was successfully controlled by AOBC, operative mortality was 11%. CONCLUSION Transbrachial arterial insertion of an AOBC may be useful to ameliorate hemorrhagic shock in patients with ruptured AAAs.


The Annals of Thoracic Surgery | 1998

Influence of functional tricuspid regurgitation on right ventricular function

Takaki Sugimoto; Masayoshi Okada; Nobuchika Ozaki; Toshihiro Kawahira; Masato Fukuoka

BACKGROUND Although right ventricular (RV) function has been extensively studied during the past decade, few reports have described the influence of functional tricuspid regurgitation (TR) on RV function. METHODS One hundred forty-two patients with left-side valvular heart disease associated with TR were enrolled in the study and divided into three groups according to tricuspid annular diameter: group 1 (n = 66), tricuspid annular diameter less than 40 mm; group 2 (n = 58), tricuspid annular diameter of 40 to 50 mm; and group 3 (n = 18), tricuspid annular diameter greater than or equal to 50 mm. In groups 2 and 3, the right heart parameters had deteriorated to the point that TR repair was necessary. The mean follow-up period was 102 months after the operation. RESULTS In each of the three groups, as pulmonary arteriolar resistance index increased, RV forward stroke work index increased in a linear fashion. The slope of the linear regression line was progressively less in group 1, 2, and 3 preoperatively. Postoperatively, this line moved in a parallel manner in group 1 and became steeper in group 2, consequently becoming similar in both groups. However, in group 3, although the slope became steeper in spite of a remarkable decrease of TR, it remained less when compared with groups 1 and 2. In addition, the right heart parameters also improved, but still remained worse in group 3 than group 2; 7 patients undergoing a flexible annuloplasty have shown gradual aggravations in TR and late postoperative clinical manifestations. CONCLUSIONS Functional TR with severely dilated annulus may produce an irreversible deterioration of RV function. The preoperative relationship between pulmonary arteriolar resistance index and RV forward stroke work index, that is, RV systolic function to pressure afterload, might predict a postoperative fate of the right heart function.


Interactive Cardiovascular and Thoracic Surgery | 2010

Spontaneous dissection of the splanchnic arteries

Nobuchika Ozaki; Noboru Wakita; Akitoshi Yamada; Yosuke Tanaka

Three patients had severe abdominal pain of sudden onset. Computed tomography showed localized dissection in the superior mesenteric artery in two patients and in the celiac artery in one. With conservative therapy abdominal symptoms were self-remitted. All patients were successfully treated with medication and have been doing well during follow-up.


Surgery Today | 2007

Primary Cardiac Liposarcoma Causing Cardiac Tamponade: Report of a Case

Aki Kitamura; Nobuchika Ozaki; Nobuhiko Mukohara; Masato Yoshida; Tsutomu Shida

The intracardiac growth and extension of liposarcoma was observed in a 60-year-old woman. The epicardial tumor was identified to originate from the anterior wall of the right ventricle. She initially showed symptoms associated with cardiac tamponade. A surgical operation was performed but it resulted in incomplete resection due to massive invasion and dissemination. The recurrence of the tumors led to congestive heart failure. Finally, she died of heart failure and liver dysfunction as a result of tumor metastasis and invasion. An autopsy detected the primary cardiac liposarcoma. Only a few cases of cardiogenic liposarcoma have so far been reported. A further elucidation of cardiac liposarcoma could reveal mechanisms of the disease, and thus contribute to development of complementary therapies after surgical intervention.


The Cardiology | 1998

Evidence of Apoptosis Induced by Myocardial Ischemia: A Case of Ventricular Septal Rupture following Acute Myocardial Infarction

Yoshiya Toyoda; Tsutomu Shida; Noboru Wakita; Nobuchika Ozaki; Rei Takahashi; Masayoshi Okada

Recent studies have reported that apoptosis may be induced by reperfusion injury following ischemia in cardiomyocytes. We present a case with evidence of apoptosis induced by myocardial ischemia without reperfusion. DNA fragmentation was demonstrated in the nuclei of the myocardial cells surrounding the ventricular septal rupture following acute myocardial infarction without reperfusion in the infarct-related left anterior descending coronary artery. This finding suggests that ischemia without reperfusion may induce apoptosis in myocardial cells.


Surgery Today | 2007

Inflammatory aneurysm of the ascending aorta: report of a case.

Masato Yoshida; Nobuhiko Mukohara; Tasuku Honda; Nobuchika Ozaki; Tsutomu Shida

Inflammatory aortic aneurysms are found most commonly in the infrarenal abdominal aorta. We report the case of a 78-year-old man with an inflammatory aortic aneurysm of the ascending aorta, which is extremely unusual. Surgery revealed that the ascending aorta was adherent to the superior vena cava and pulmonary artery, but a dissection membrane was not found. The wall of the ascending aorta was up to 20 mm thick with perianeurysmal fibrosis. Pathologic examination revealed an inflammatory aneurysm with adventitia remarkably thickened by fibrotic tissue and infiltrated by lymphocytes and plasma cells. Our search of the literature found only seven other cases of an inflammatory ascending aortic aneurysm. Preoperative diagnosis was very difficult in most of these cases; however, improved scanning techniques using multidetector row computed tomography may allow the differential diagnosis of this clinical entity.


Radiation Medicine | 2006

Percutaneous balloon fenestration and stent placement for lower limb ischemia complicated with type B aortic dissection

Masato Yamaguchi; Koji Sugimoto; Yoshihiko Tsuji; Nobuchika Ozaki; Masakatsu Tsurusaki; Takanori Taniguchi; Carlos A. Zamora; Yutaka Okita; Kazuro Sugimura

We report a case of lower limb ischemia secondary to type B aortic dissection, which was successfully treated with endovascular aortic fenestration and stent placement. In this case, we were not able to restore adequate flow to the ischemic limb by means of aortic balloon fenestration alone, so additional stent placement was required to buttress the true lumen and fenestra. There was no recurrence of lower limb ischemia complications during the follow-up period. Aortic balloon fenestration with stent placement seems to be a safe and effective technique to salvage an ischemic lower limb complicated by acute aortic dissection.


The Japanese Journal of Thoracic and Cardiovascular Surgery | 2006

Pulmonary thromboendarterectomy for chronic pulmonary thromboembolism in protein C deficiency.

Masato Yoshida; Nobuhiko Mukohara; Hidefumi Obo; Nobuchika Ozaki; Tsutomu Shida; Yutaka Okita

Pulmonary thromboendarterectomy was performed on a patient with chronic pulmonary thromboembolism showing thrombophilia. The patient was a 56-year-old female with the above condition complicated by congenital protein C deficiency. She was admitted to our hospital with severe dyspnea accompanied by right ventricular failure. A pulmonary arteriogram showed occlusion and stenosis from lobar to segmental arteries. Cardiac catheterization showed marked pulmonary hypertension. A lung perfusion scintigram revealed multiple defects in the right and left lungs. After the insertion of an inferior vena cava filter, she was operated on. Following a median sternotomy, thromboendarterectomy of the bilateral pulmonary arteries was performed using deep hypothermia and intermittent circulatory arrest. Circulatory arrest was employed in three periods totaling up to 36 minutes. After surgery, she had improvements in pulmonary hypertension and pulmonary vascular resistance. She maintained improved lung functions, and remained in the New York Heart Association functional class I for more than two years and eight months after surgery.


European Journal of Cardio-Thoracic Surgery | 2012

The life-threatening complication of a vascular graft rupture early after a thoracic aortic replacement

Nobuchika Ozaki; Noboru Wakita; Yosuke Tanaka; Daisuke Yuji

A 74-year old male presented with a dilatation of the thoracic aorta late after an acute aortic dissection. Computed tomography (CT) showed chronic dissecting aortic aneurysms just below the distal aortic arch. The total descending thoracic aorta was surgically replaced. Four weeks later, a massive bloody effusion developed in the right thorax and a subsequent CT scan revealed an extravasation of the contrast material out of the vascular prosthesis. Emergency surgery disclosed bleeding from a small vascular graft rupture and a successful repair was performed.

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