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Biomedical subjects

Kohei Kawazoe

Publications and source records attributed to Kohei Kawazoe.

At least 19 recordsLinked to original sources
PubMed2006

Risk factors for hypoxemia after surgery for acute type A aortic dissection.

PURPOSE: Postoperative hypoxemia is a frequent complication of surgery for acute type A aortic dissection. We tried to determine the factors associated with postoperative hypoxemia. METHODS: Between 1997 and 2003, 114 patients underwent surgery for acute type A aortic dissection. Multivariate logistic regression analysis was done to identify the independent predictors of postoperative hypoxemia, defined by an arterial partial oxygen/inspired oxygen fraction (PaO(2)/FiO(2)) ratio of 200 or lower. RESULTS: The overall in-hospital mortality was 6.1% (7 of 114 patients), being 5.2% in the hypoxemia group and 6.9% in the non-hypoxemia group. The ventilation time and intensive care unit stay were significantly longer in the hypoxemia group than in the non-hypoxemia group (P = 0.0044, P = 0.038, respectively). Logistic regression identified the following variables as predictors for postoperative hypoxemia: body mass index > or = 25 (odds ratio [OR], 5.6; 95% confidence interval [CI], 2.1-15.01; P < 0.001), preoperative PaO(2)/FiO(2) ratio < or = 300 (OR, 2.6; 95% CI, 1.09-6.13; P = 0.031), and the volume of transfused blood (OR, 1.08; 95% CI, 1.01-1.18; P = 0.037). CONCLUSIONS: Initiating early treatment for hypoxemia and reducing the volume of blood transfused intraoperatively may improve the postoperative clinical course of obese patients with preoperative hypoxemia.

Adult↗
PubMed2006

MR angiography and CT angiography of the artery of Adamkiewicz: state of the art.

It is very important to assess the artery of Adamkiewicz before repair of the thoracoabdominal or descending thoracic aorta. Several studies have demonstrated the feasibility and advantages of noninvasive assessment of the artery of Adamkiewicz with magnetic resonance (MR) angiography and multi-detector row computed tomographic (CT) angiography. Recent advances in MR angiography and CT angiography have led to changes in the detectability of this artery. In the present study, both MR angiography and CT angiography were performed without complications for preoperative evaluation of 30 patients who underwent repair of the thoracoabdominal or descending thoracic aorta. MR angiography provided detection rates as high as 93% and 80% with the morphologic "hairpin turn" criterion and the anatomic "continuity" criterion, respectively. Sixteen-detector row CT angiography provided detection rates as high as 83% and 60%, respectively. Use of both MR angiography and CT angiography provided higher detection rates of 97% and 90%, respectively. The collateral pathways were depicted in seven cases (23%). MR angiography is superior for depiction of the artery of Adamkiewicz, especially when it arises from the false lumen of a dissecting aneurysm. CT angiography has a wide field of view and allows depiction of significant collateral pathways associated with the internal thoracic artery and intercostal arteries.

Adult↗
PubMed2006

Magnetic resonance angiography in coronary artery bypass grafting.

An attempt was made to reduce the incidence of perioperative stroke by detecting cerebrovascular disease with preoperative head and neck magnetic resonance angiography and by selecting the coronary artery bypass grafting technique. This strategy was used in 268 patients with ischemic heart disease who had undergone both head and neck magnetic resonance angiography before elective coronary artery bypass in our hospital between May 1997 and April 2001. In patients with significant stenosis or obstruction detected by head and neck magnetic resonance angiography, the findings were evaluated and cerebral blood flow was examined using brain single-photon emission computed tomography. In those with a high risk of cerebrovascular ischemia, off-pump coronary artery bypass was performed to maintain cerebral blood flow. No stroke occurred during surgery, and hemodynamic cerebrovascular ischemia was prevented in all 268 patients. Postoperative stroke occurred in 3 patients (1.1%), but the incidence of perioperative stroke was reduced.

Adult↗
PubMed2006

[Surgical treatment of ischemic mitral regurgitation].

Ischemic mitral regurgitation (IMR) is a serious problem, which conveys adverse prognosis, doubling mortality after myocardial infarction. It is common and increases mortality even when mild. IMR is often associated with the occlusion of left circumflex coronary artery, such as second or third obtuse marginal branches by experimental model. However, cause of IMR still remains unclear in many respects. Several study using echocardiography and magnetic resonance imaging show some probable reasons left ventricular structure and deformity of left ventricle may cause mitral leaflet restriction and mitral annulus deformity, lead to tethering. The aim of surgical treatment of IMR is to reduce the grade of mitral regurgitation and left ventricular remodeling. Recent study clarified the advantage of valve repair in IMR opposed to valve replacement that may affect the patient poor quality of life. Some new technique of saddle shaped ring repair, second chordal cutting, edge-to-edge repair are available but these long-term outcome remain unclear. It may be effective combined left ventricular revascularization and mitral valve repair. Understanding mechanism of IMR will improve therapies for targeted primary causes with new therapeutic options provided a more flexible approach for surgical repair of IMR.

Cardiac Surgical Procedures↗
PubMed2006

Aortic valve repair for aortic regurgitation: intermediate-term results in patients with tricuspid morphology.

BACKGROUND AND AIM OF THE STUDY: Surgical results after aortic valve repair in patients with aortic regurgitation (AR) of tricuspid valve morphology and with no evidence of aortic root disease have not yet been clarified. METHODS: Between January 1994 and June 2001, aortic valve repair was performed in 40 patients (eight females, 32 males; mean age 61.0 +/- 10.5 years) of this type. Surgical results and follow up data were summarized after aortic valve repair (for AR) in these patients. RESULTS: One patient died in hospital (mortality 2.5%). The mean cardiopulmonary bypass time was 143.5 +/- 47.4 min, and mean aortic cross-clamp time 99.8 +/- 34.3 min. At follow up, the mean AR grade was 1.5 +/- 0.8 and mean NYHA class 1.0 +/- 0; both parameters showed significant improvement compared to preoperative status (p < 0.0001). Survival was 94.9% at one year and 82.6% at five years. The five-year reoperation-free rate was 87%. CONCLUSION: Aortic valve repair for AR in patients with tricuspid valve morphology is a safe procedure that provides good intermediate-term results.

Aortic Valve Insufficiency↗
PubMed2006

[Development of 64-channel magnetocardiography and clinical application].

A magnetocardiogram (MCG) can detect three-dimensional electric phenomena of the heart, because MCG does not influence the lung and torso form of the internal organs. In this symposium, we report the application of 64-channel MCG for the measurement of various arrhythmias (atrial flutter, atrial fibrillation), myocardial injury, and fetus arrhythmia. We composed function images of the conduction wave front and injured myocardium superimposed on a three-dimensional heart outline from the magnetic field. The injured myocardium was determined by a three-dimensional RT dispersion map. This algorithm allows the non-invasive determination of the space location of signal source and injured myocardium. In addition, 64-channel MCG can detect the fetal arrhythmias and autonomic nervous activity, which allows the diagnosis of fetus arrhythmia in detail before birth. Thus, MCG measurement is a useful non-invasive diagnostics procedure. However, there are several problems such as sealed room installation and the use of liquid helium. In the future, a newer technology that does not require liquid helium and a sealed room will be necessory.

Arrhythmias, Cardiac↗
PubMed2006

Dynamic morphologic changes in the normal aortic annulus during systole and diastole.

BACKGROUND AND AIM OF THE STUDY: The three-dimensional motion of semilunar attachment of the leaflet 'annulus' remains obscure. It has been suggested that the aortic root is distensible and moves during the cardiac cycle. In the present study, the aortic root was evaluated using two dimensions. The aortic root, notably motion of the aortic annulus, was evaluated using multidetector computed tomography (MDCT), and a three-dimensional reconstruction of the aortic annulus was performed. METHODS: Twenty-five patients (17 males, eight females) underwent MDCT. None of the patients had aortic root disease, aortic valve disease, bicuspid valve, myocardial infarction or atrial fibrillation. The aortic annulus was measured in systole and diastole, and divided into three parts: the right coronary cusp (RCC), left coronary cusp (LCC) and non-coronary cusp (NCC). The lengths of the aortic annulus, sinus of Valsalva and sinotubular junction (STJ) were also measured in systole and diastole on longitudinal views. RESULTS: The lengths of each aortic annulus part in systole and diastole were as follows. In systole: RCC 41.8 +/- 8.1 mm; LCC 39.3 +/- 5.9 mm; NCC 43.7 +/- 7.1 mm. In diastole: RCC 42.4 +/- 7.0 mm; LCC 38.6 +/- 7.8 mm; NCC 41.5 +/- 7.8 mm. No statistically significant differences were observed between lengths in systole and diastole. The longitudinal lengths of aortic annulus, sinus of Valsalva and STJ at each period were as follows. In systole: aortic annulus 22.5 +/- 2.2 mm; sinus of Valsalva 34.9 +/- 4.3 mm; STJ 28.1 +/- 3.2 mm. In diastole: aortic annulus 22.1 +/- 2.2 mm; sinus of Valsalva 34.4 +/- 4.7 mm; STJ 27.2 +/- 3.1 mm. The length of the STJ in systole was significantly greater than that in diastole. CONCLUSION: In the normal aortic root, no part of the aortic annulus changed length during the cardiac cycle. According to changes in aortic root dimensions, the commissures move outwards during the systolic phase.

Adult↗
PubMed2005

Three-dimensional recovery time dispersion map by 64-channel magnetocardiography may demonstrate the location of a myocardial injury and heterogeneity of repolarization.

BACKGROUND: QT dispersion reveals heterogeneities in the repolarization time in the three-dimensional (3D) structure of the ventricular myocardium. In this study, we report on a 3D function map of recovery time (RT) dispersions as measured by 64-channel magnetocardiography (MCG). METHODS: MCG were simultaneously recorded in 29 controls and 21 patients with previous myocardial infarction (MI). The 3D current density was calculated from 64-channel MCG data in the Bz component using a space filter. The heart outline, reconstructed from the integrated the current density, revealed both the atrium and ventricle. The RT for the intervals between QRS onset and the time of the maximum dT/dt of T wave, and the peak to the end of the T wave (T(peak)-negative dT/dt) were automatically measured by means of a computer from 3D MCG data. The corrected RT (RTc) and corrected T(peak)-negative dT/dt were then calculated using Bazett's formula. The 3D RTc and the corrected T(peak)-negative dT/dt dispersion map were superimposed on the heart outline generated by MCG. RESULTS: The RTc was significantly longer for the MI group than in the control group (67+/-25 ms1/2 vs. 16+/-6 ms1/2) (p<0.0001). The corrected T(peak)-negative dT/dt dispersions in each patient was also significantly longer for the MI group than in the control group (35+/-27 ms1/2 vs. 10+/-5 ms1/2) (p<0.0001). Furthermore, the 3D RTc and T(peak)-negative dT/dt dispersion maps corresponded with the space location of MI, as defined by Tc-99m tetrofosmin myocardial imaging CONCLUSIONS: 3D RTc and T(peak)-negative dT/dt dispersion maps in the ST segment, obtained by 64-channel MCG may be used demonstrate the location of a myocardial injury and heterogeneities of repolarization.

Adult↗
PubMed2005

Influence of gelatin-resorcin-formalin glue on mid-term redissection after aortic repair.

PURPOSE: To determine whether the development of mid-term redissection after surgery for acute type A aortic dissection using gelatin-resorcin-formalin (GRF) glue could be prevented by applying less formalin. METHODS: Between 1995 and 1999, 59 patients underwent surgery with GRF glue to repair acute type A aortic dissection. Forty-one patients underwent surgery before October 1998, and 18 patients underwent surgery after November 1998. An excessive amount of formalin was used in the former period and less was used in the latter period. RESULTS: Follow-up computed tomography was done for 34 patients in the former period (Former group) and for 16 patients in the latter period (Latter group). This showed redissection in 19 of the 34 patients in the Former group and in 6 of the 16 patients in the Latter group. There was no significant difference in the frequency of mid-term redissection between the two groups. CONCLUSION: The development of mid-term redissection of the aortic root was not prevented by applying less formalin in the GRF glue. Thus, we conclude that the cause of redissection is not entirely the result of too much formalin.

Aged↗
PubMed2005

Head and neck magnetic resonance angiography before coronary artery bypass grafting.

PURPOSE: To evaluate the incidence of vascular lesions in the head and neck by magnetic resonance angiography (MRA), and investigate the factors correlated with severe stenosis. METHODS: Elective coronary artery bypass grafting (CABG) was performed in 413 patients at our center between May 1997 and April 2001. We used MRA to detect head and neck vascular lesions, then evaluated the occlusive lesions and determined their prevalence. RESULTS: Neck MRA was performed in 335 patients and head MRA was performed in 335 patients. We found > or = 60% stenosis or total occlusion of the extracranial carotid and vertebral artery in 43 patients (12.8%) and > or = 60% stenosis or occlusion of the intracranial carotid and basilar artery, or stenosis accompanied by poor peripheral perfusion or occlusion of the cerebral arteries in 45 patients (13.4%). Occlusive lesions of the neck were significantly correlated with mean age, peripheral vascular disease (PVD), and old myocardial infarction. Occlusive lesions of the brain were significantly correlated with age, hypertension, PVD, and left main trunk disease. CONCLUSIONS: We found an equal incidence of intracranial and extracranial vascular lesions. Thus, searching for intracranial lesions is just as important as searching for extracranial lesions before CABG.

Adult↗
PubMed2005

Late complications following surgery for type A acute aortic dissection using gelatin-resorcin-formaldehyde glue: report of two cases.

Gelatin-resorcin-formaldehyde (GRF) glue has been widely applied during operations for acute aortic dissection (AAD). At our institution, GRF glue was applied in 40 patients who underwent surgical procedures for AAD from 1995, two of whom needed a reoperation because of the development of a redissection and/or a pseudoaneurysm at the anastomotic sites. The operative findings and histological examinations suggested that the application of GRF glue during the initial operations might be related to the development of a redissection and/or a pseudoaneurysm.

Aged↗
PubMed2005

Construction of a three-dimensional outline of the heart and conduction pathway by means of a 64-channel magnetocardiogram in patients with atrial flutter and fibrillation.

BACKGROUND: Magnetocardiography (MCG) has the potential for collecting three-dimensional (3D) intracardiac electric information, because the magnetic field is unaffected by the shape of the lungs and torso. In the present study, we report on the generation of a 3D heart outline and conduction pathway by means of a current density map using a 64-channel SQUID system, and an evaluation of its significance in patients with atrial flutter (AFL) and atrial fibrillation (AFIB). METHODS: The subjects consisted of 20 healthy volunteers, and 3 patients with AFL and 4 patients with AFIB. A 64-channel MCG was recorded after digitization at 500 Hz, and a 3D current density was reconstructed from the magnetic fields using a space filter in conjunction with the minimum normalization method of Tikhonov. A 3D heart outline was generated from the integrated current density by the space filter. The conduction pathway was superimposed on a heart outline generated by a magnetic field. The heart outline was verified by the silhouette on the magnetic resonance (MR) images. An MCG was recorded pre- and post interventional therapy, and therapeutic efficacy was evaluated. RESULTS: The 3D heart outline of the atrium and ventricle corresponded to the silhouette of the right atrium and left ventricle, respectively, on an MR image. The serial conduction pathway of the QRS segment superimposed on the 3D heart outline map demonstrated the conduction pattern generated within the heart. The MCG revealed a counter-clockwise rotation in patients with AFL, and random micro-reentry in the case of AFIB. After interventional therapy, restoration of the sinus rhythm was verified in patients with both AFL and AFIB. CONCLUSIONS: A 64-channel MCG was used to evaluate the 3D heart outline and conduction pathway in patients with AFL and AFIB without the need for MR images. Condensed Abstract A 64-channel MCG was used to evaluate the 3D heart out line and conduction pathway in patients with AFL and AFIB.

Aged↗
PubMed2005

Effective use of fibrin glue for acute aortic dissection.

The use of gelatin-resorcine-formalin (GRF) glue for reconstruction of the vascular wall in the context of acute aortic dissection has become more common. However, anecdotal evidence suggests that use of the GRF glue results in higher rates of postoperative redissection. We describe an alternative method of reinforcing the dissected aorta with fibrin glue that may avoid this complication. A fabric sheet is presoaked in fibrinogen solution and then placed within the false lumen. Thrombin solution is then applied to the fabric sheet. That results in obliteration of the false lumen and effective reinforcement of the dissected wall.

Aortic Aneurysm, Thoracic↗