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Biomedical subjects

Kazuhito Imanaka

Publications and source records attributed to Kazuhito Imanaka.

At least 19 recordsLinked to original sources
PubMed2006

Importance of luxury flow for critically ill patients receiving a left ventricular assist system.

The presence of a significant organ dysfunction does not immediately exclude patients from consideration for treatment with a left ventricular assist system (LVAS). However, in treating morbid circulatory shock patients with multiple organ failure, it is important to know the preoperative and postoperative factor or factors related to the recovery of the damaged organ function. In this study, we retrospectively analyzed patients receiving a LVAS at our institution and tried to determine the important factors related to the survival of patients with multisystem failure. Twenty-seven patients who underwent LVAS placement at Saitama Medical School Hospital between 1993 and 2003 were included in this study. The preoperative risk factors analyzed were renal dysfunction, respiratory dysfunction, hepatic dysfunction, the existence of active infection, and the combination of all four factors. As a postoperative factor, the pump flow index (mean LVAS pump flow during the first 2 weeks after LVAS surgery divided by the body surface area) was analyzed. None of the analyzed preoperative factors could predict survival after LVAS surgery, but a pump flow index of less than 2.5 l/min/m2 had a significant relationship with death after LVAS surgery. Further analysis revealed that all the patients with a pump flow index of 3.0 l/min/m2 or more could overcome preoperative organ dysfunction. Congestive heart failure patients with multisystem failure need luxury pump flow for successful LVAS surgery; this factor could be especially important in device selection and postoperative management.

Cardiac Output↗
PubMed2006

Active cerebral perfusion during carotid endarterectomy.

A patient with critical stenoses in the bilateral internal carotid arteries (ICA) required multivessel coronary revascularization. The diameter of the left ICA was far greater than the right, which strongly suggested that the cerebral circulation was highly dependent on the left. During left ICA endarterectomy, active cerebral perfusion of 300 mL x min(-1) at 23 degrees C using an extracorporeal circulation was employed through the ICA under repair. Subsequently, coronary bypass was performed on-pump with the heart beating. The postoperative course was very good.

Carotid Artery, Internal↗
PubMed2006

[Successful salvage of a patient with cardiac arrest caused by multiple pulmonary emboli and lung abscesses due to infective endocarditis of the tricuspid valve: a case report].

A 28-year-old female developed infective endocarditis in the tricuspid valve and multiple lung abscesses due to septic pulmonary emboli early after intensive therapy for ulcerative colitis. The pathogen was methicillin-resistant Staphylococcus aureus. Usual antibiotic agents and linezolid were administered. Three weeks later, she fell into cardiopulmonary arrest due to further pulmonary emboli and required mechanical circulatory assist. Fatal brain damage was suggested at first. Two days later, she fully regained consciousness and underwent tricuspid valve replacement using mechanical valve and extirpation of septic pulmonary embolus. Mechanical circulatory assist was discontinued on the next day. After strenuous administration of linezolid and other drugs for 9 weeks, she was discharged from hospital on foot. We believe that early surgical intervention should be considered in patients with infective endocarditis in the right heart and subsequent septic pulmonary emboli. Linezolid was very useful in this patient.

Acetamides↗
PubMed2005

Impact of postoperative blood pressure control on regression of left ventricular mass following valve replacement for aortic stenosis.

OBJECTIVE: Considerable left ventricular (LV) hypertrophy sometimes remains after aortic valve replacement (AVR) for aortic stenosis. For this issue, most previous studies have focused solely on transprosthetic pressure gradient, although true problem is not the pressure gradient itself but an elevated LV pressure. This study investigated the impact of blood pressure on postoperative LV mass regression, which had been overlooked in previous studies. METHODS: Seventy-nine adult patients with pure aortic stenosis who were treated with AVR using bileaflet mechanical valves underwent echocardiography before surgery, around 6 months later ('early'), and 2-3 years later (31.7+/-14.7 months, 'late'). Patients were divided into two groups whether postoperative systolic blood pressure was below (n=47; N group) or above 130 mmHg (n=32; H group) following recommendation of WHO-ISH and JNC 7th report. Preoperative LV mass (g/m2) did not differ significantly (232+/-80 vs. 243+/-76, P=0.91). RESULTS: LV mass became significantly smaller and regression was significantly more effective in N group than in H group both at 'early' (145+/-43 vs. 180+/-54, regression against preoperative value 34.6+/-19.1 vs. 19.9+/-26.6%, P=0.007) and 'late' (132+/-41 vs. 178+/-51, regression 41.1+/-16.0 vs. 21.0+/-27.0%, P<0.001) evaluations. Regression between 'early' and 'late' evaluations was significant only in N group (P=0.012). The LV mass index returned to the normal range at 'late' evaluation in 52.1% of N group and 12.5% of H group patients (P<0.001), and 25 out of 29 patients without residual LV hypertrophy were N group patients. Multivariate analyses revealed that preoperative LV mass index (P<0.001) and postoperative systolic blood pressure (P=0.007) showed significant influence on postoperative LV mass index, and postoperative systolic blood pressure alone significantly (P<0.001) influenced the regression ratio of the LV mass against the preoperative value. No prosthesis related variables (size, orifice area index, pressure gradient) had significant influence. CONCLUSIONS: For LV mass regression after AVR, postoperative blood pressure appeared to be more important than prosthesis selection. Controlling the systolic blood pressure below 130 mmHg was beneficial, which coincided with recommendation of WHO-ISH and JNC 7th report despite the pressure drop due to prosthesis in the aortic position.

Aged↗
PubMed2005

Successful bridge to resynchronization therapy with a left ventricular assist system in a patient with idiopathic dilated cardiomyopathy.

Implantation of a left ventricular assist system (LVAS) in patients with idiopathic dilated cardiomyopathy (DCM) may improve cardiac function and allow explantation of the device. Generally, an ejection fraction of more than 40% is considered necessary for successful weaning from an LVAS, but less than 10% of DCM patients with an LVAS can achieve such a significant recovery of cardiac function. Cardiac resynchronization therapy, or atrial-synchronized biventricular pacing, has been found to treat congestive heart failure and ventricular dyssynchrony effectively. Here we report on a patient with an LVAS, in whom enough functional recovery could be obtained with resynchronization therapy for the device to be explanted successfully. A 32-year-old man was implanted with a Toyobo-NCVC paracorporeal LVAS to treat his intractable heart failure caused by idiopathic dilated cardiomyopathy. While on the LVAS for 8 months, his cardiac function recovered to some extent. The ejection fraction of his left ventricle (LVEF) improved from 9% to 41%. He chose explantation of the device rather than heart transplantation. Because he occasionally showed a wide QRS pattern on his ECG, epicardial biventricular pacing leads as well as a biventricular pacemaker were implanted on LVAS explantation surgery. An echocardiogram 2 weeks after explantation showed a marked difference in his LVEF by switching his biventricular pacing on and off (40% with biventricular pacing on and 29% with it off). Biventricular pacing may help recovery of cardiac function in selected LVAS patients and contribute to the increase in bridge to recovery cases.

Adult↗
PubMed2005

[Coronary artery bypass grafting in patients undergoing chronic hemodialysis: importance of wound healing and hypoproteinemia].

OBJECTIVES: Outcome of coronary artery bypass grafting (CABG) in patients undergoing chronic hemodialysis was studied. METHODS: Between January 1996 and August 2004, 49 consecutive hemodialysis patients [38 males and 11 females, mean age 60.0 years (range 47-74 years)] underwent CABG using cardiopulmonary bypass. Duration of hemodialysis was 5.2 years (range 1 month-21 years), and 32 patients were diabetics. Surgery was conducted on the emergency/urgency basis in 12 patients, and intraaortic balloon pumping was placed in 7. Left ventricular ejection fraction was 57.7 +/- 16.3% (range 27-84%). Nine patients underwent concomitant valve surgery. CABG was performed under hypothermic cardiopulmonary bypass and ventricular fibrillation except in one patient, and intraoperative hemodialysis was also performed. Continuous hemodiafiltration was used in the early period after surgery. RESULTS: Number of bypass grafts was 3.0 +/- 1.0 (range 1-6), and the unilateral internal thoracic artery was used in 29 patients. Operation time, cardiopulmonary bypass time, and aorta clamp time were 313 +/- 87, 145 +/- 63, and 49 +/- 43 min, respectively. Diffuse pericardial adhesion was present in five patients. Severely atheromatous ascending aorta precluded manipulation in seven patients. Although the 30-day mortality was 2.0% (one case), all in-hospital mortality over 9 months was 14.3% (seven cases). The morbid events were mediastinitis in seven cases, reexploration for hemorrhage in seven, pneumonia in two, abdominal complication in three, and stroke in one. Delayed onset mediastinitis was common. Risk factors for death were mediastinitis and serum albumin levels < 3.5 g/dl (both p < 0.05), both of which were wound healing-related factors. CONCLUSIONS: CABG in hemodialysis patients carries a high risk. Patients with hypoalbuminemia appear to require special consideration.

Aged↗
PubMed2005

[Perioperative cardiovascular evaluation and management for non-cardiac surgery in patients with valvular heart disease].

A significant perioperative cardiac morbidity and mortality should be anticipated during non-cardiac surgery when patients have cardiac risks. Especially the non-cardiac surgical risk is very high in the patient with aortic stenosis. Non-cardiac surgery should be postponed to cardiac interventions, such as balloon valvuloplasty or prosthetic valve replacement, in patients with severe heart failure. Non-cardiac surgery can be performed with a relatively low risk even if the patients have a symptomatic regurgitatant valvular heart diseases, however, the cardiac risk is always very high in the patients with left ventricular ejection fraction lowerer than 40%. Surgical invasion, anesthetic agents, analgegic agents, and fluid transfusion during the non-cardiac surgery will give a significant effects on the circulatory condition, therefore, non-cardiac surgery should be performed with an adequate cardiac monitoring and careful perioperarive managements according to the pathophysiology of each valvular heart disaease. Afterload control is very important in the patients with regurgitant valvular heart diseases, contrary preload control is very important in the patients with stenotic valvular heart diseases. Anesthetic agents and methods are not the determinant factor of the clinical outcome, but the associated cardiac diseases and the surgical procedure are important determinant factor of the clinical outcome of the non-cardiac surgery.

Blood Pressure↗
PubMed2005

[Active infective endocarditis remaining latent for six weeks after discontinuation of antibiotic therapy: a case report].

A 75-year-old man was treated for 4 weeks with penicillin administration for infective endocarditis in the mitral valve caused by Enterococcus faecalis. The infection recurred, so he received penicillin administration for a further 6 weeks. He remained afebrile and all laboratory examinations were within normal limits for 6 weeks after the antibiotic treatment was discontinued, but the vegetation remained large and highly mobile. Since the onset, possible embolic episodes had occurred three times. He underwent mitral valve repair with annuloplasty. Although the infection appeared to have healed by antibiotic therapy, resected tissue was strongly positive for Enterococcus faecalis. This case suggests that surgery should be aggressively considered if the vegetation does not shrink markedly.

Aged↗
PubMed2004

Lethal thrombus in the carotid artery during operation for acute aortic dissection with cerebral malperfusion.

A drowsy patient with acute type A aortic dissection and cerebral malperfusion required emergency operation. Because the right carotid artery was totally obstructed, cerebral perfusion was first restored by cannulating it and the left femoral artery before midline sternotomy. However, a long fresh thrombus was found flowing backward from the obstructed carotid artery. This thrombus was removed, and both arteries were connected through a Y-shaped extracorporeal circulation circuit to reperfuse the brain. During the subsequent aortic procedure, both arteries were used for arterial inflow. Such thrombi can cause grave postoperative neurologic dysfunction. Carotid artery cannulation is mandatory in such cases.

Acute Disease↗
PubMed2004

Successful treatment of ascending aortic graft infection after operation for acute aortic dissection with peripheral malperfusion.

Mediastinitis with infection of an ascending aortic graft is hard to heal and is a highly fatal complication. We had a patient in whom mediastinitis with infection of such a graft as well as an ascending aorta-femoral artery bypass graft developed after the initial operation for type A aortic dissection accompanied by peripheral malperfusion. We treated it successfully by inserting a stent into the true lumen of the thoracoabdominal aorta and using a cryopreserved homograft to replace the infected ascending aortic fabric graft.

Acute Disease↗
PubMed2004

Surgery for active, culture negative endocarditis.

Culture negative infective endocarditis (CNE) poses very difficult problems during treatment. In this study it was found that of 132 surgically treated patients with infective endocarditis, causative organism was not identified in 46 (34.8 %). Pre- and perioperative conditions and clinical results of these patients were evaluated. CNE remained very frequent even in these years, and it did not decrease with time. Antibiotic treatment prior to microbiological examinations was commonly observed (nearly 90% orally, and 70% intravenously). In average, it took more than 2 months to establish the diagnosis of CNE after the onset, and both aortic and mitral valves were affected frequently (19.0 %). New York Heart Association functional class IV was observed significantly more commonly (61.9%) than culture positive patients. Frequencies of prosthetic valve endocarditis (12.2%), periannular abscess (36.3%), and embolism (21.4%) were similar. Infection was fairly controllable before surgery in 43.9% of CNE patients and in-hospital mortality rate was 14.3%, both of which were comparable to those of all culture positive patients. However, recurrence rate was relatively higher (10.0%). The conditions and outcomes of CNE were comparable to Staphylococcal endocarditis in some aspects, and were relatively worse than overall culture positive endocarditis.

Adult↗
PubMed2004

[Aortic root replacement using an allograft for active infective endocarditis with periannular abscess: single center experience].

OBJECTIVES: Results of aortic root replacement using an allograft for active infective endocarditis in the aortic position and periannular abscess were studied. METHODS: Aortic root replacement using a cryopreserved aortic allograft was performed 13 times in 12 patients (9 men, 3 women, mean age 52.8 years) at Saitama Medical School. Allografts were obtained from the Tokyo University Tissue Bank. Infection affected the prosthetic valve in 6 patients and the native valve in 7. Causative organisms were Staphylococci in 7 patients, Streptococci in 2, and unknown in 4. New York Heart Association functional class was II in 2 patients, III in 3, and IV in 8. Six patients required inotropic support. Four were mechanically ventilated. Two were in a state of profound shock. Four had multiple organ failure. Surgery was conducted under hypothermic cardiopulmonary bypass and cardioplegic arrest. Allograft was sewn into place by monofilament continuous sutures. Carrel patch technique was used for coronary artery reconstruction. Five patients underwent concomitant procedures (replacement of the ascending aorta in 2 patients, coronary artery bypass grafting in 1, mitral valve repair in 1, pulmonary artery reconstruction in 1). RESULTS: Duration of surgery, cardiopulmonary bypass, and aortic clamping were 507 +/- 154, 307 +/- 111, and 189 +/- 49 min, respectively. Two patients required intraaortic balloon pumping, and one required percutaneous cardiopulmonary support. Two patients in a state of shock died(hospital mortality: 15.4%). Duration of mechanical ventilation was 2.9 +/- 3.7 days. Intensive care unit stay was 4.6 +/- 5.5 days, and hospital stay was 61 +/- 26 days. One patient died of cancer 18 months later. One patient required reoperation 11 months later. Including operative death cases, cumulative survival at 2 years was 66.5% and freedom from cardiac events was 72.7%. CONCLUSIONS: Aortic root replacement with an allograft yielded acceptable clinical results.

Abscess↗
PubMed2004

[Surgical treatment of active infective endocarditis: analysis of 20 years' experience].

OBJECTIVES: Changes in perioperative condition and outcomes of surgically treated patients with active infective endocarditis were evaluated during the last 20 years. METHODS: Between 1983 and 2002, 132 patients with active infective endocarditis underwent surgery at Saitama Medical School. Changes in frequency, pathogens, clinical features, surgical results, and perioperative treatment were compared between four periods of 5 years. RESULTS: The percentage of surgery for infective endocarditis remained almost the same among all cardiovascular procedures. Staphylococcal infective endocarditis increased significantly (p < 0.01), and prosthetic valve infective endocarditis and periannular abscess became more common. Surgery tended to be performed in severely ill patients significantly more frequently (p < 0.01). If all patients were included, hospital mortality did not decrease significantly, at 1.7% in stable patients, but 50% in critically ill patients. Intensive care unit stay became relatively longer. Recurrent infection was observed significantly more frequently in critically ill patients and in patients with prosthetic valve infective endocarditis. Patients were referred for surgery following diagnosis and underwent surgery at increasingly more appropriate timing. However, the diagnosis of infective endocarditis took 1.5 months to establish regardless of the patient's condition or the clinical outcome. Moreover, antibiotics were administered orally in around 90% and intravenously in nearly 70% of the patients without microbiological tests, and negative cultures remained very frequent. CONCLUSIONS: Critically ill patients underwent surgery increasingly more frequently, and surgical outcomes remained unsatisfactory over the last 20 years. Early diagnosis and avoidance of premature antibiotic therapy may be important for future improvement.

Endocarditis, Bacterial↗
PubMed2004

[Pseudoaneurysm of the left ventricle following suppurative pericarditis and sepsis due to Staphylococcus aureus: a case report].

A 35-year-old diabetic man presented with a left ventricular aneurysm very close to the mitral valve annulus. He had been conservatively treated for suppurative pericarditis and sepsis due to Staphylococcus aureus during the previous 3 weeks. The left ventricular aneurysm rapidly enlarged (6 cm in diameter) and the patient underwent emergent surgery. Cardiopulmonary bypass and cardioplegic arrest were induced, and the left ventricular aneurysm orifice was closed with a double layer of autologous pericardium. Mitral valve function was not impaired. He has been doing well for 4 years. Surgery is indicated as soon as possible after the diagnosis of infective left ventricular aneurysm.

Adult↗