PubMed Health⌕ Search

Biomedical subjects

Kiyoshi Yoshida

Publications and source records attributed to Kiyoshi Yoshida.

At least 37 records · Page 2Linked to original sources
PubMed2005

Visualization of neointima formation by optical coherence tomography.

Optical coherence tomography (OCT) has recently been proposed as a high-resolution imaging method. Our male patient, who had been treated with a coronary stent, died due to acute leukemia. Coronary artery images using intravascular ultrasound (IVUS) and OCT were obtained postmortem. We also compared the image of neointima formation after stent implantation evaluated by histopathological examination with that evaluated by IVUS and OCT. OCT visualized well-apposed stent struts and neointima formation, which could not be visualized completely by IVUS. OCT may be useful for monitoring structural changes after stent implantation.

Coronary Stenosis↗
PubMed2005

Geometric deformity of the mitral annulus in patients with ischemic mitral regurgitation: a real-time three-dimensional echocardiographic study.

BACKGROUND AND AIM OF THE STUDY: Saddle-shaped non-planarity of the mitral annulus has been investigated previously. The study aim was to further clarify the configuration of the mitral annulus in ischemic mitral regurgitation (MR) by using transthoracic real-time three-dimensional (3-D) echocardiography. METHODS: Twenty-five patients with previous myocardial infarction and left ventricular dysfunction (ejection fraction < 50%), and 10 healthy control subjects, were examined using real-time 3-D transthoracic echocardiography. The patients were allocated to either a non-MR group or an MR group. By using real-time 3-D echocardiography, the configuration of the mitral annulus was reconstructed in end-systole, and the height of the saddle-shaped mitral annulus calibrated (non-planar index). RESULTS: In controls, the mitral annulus appeared as non-planar 'saddle shape', with a non-planar index of 5.5 +/- 1.7 mm. The mitral annulus was flattened in both the non-MR and MR groups. The non-planar index was significantly smaller in the MR group than in the non-MR group (1.7 +/- 1.8 mm versus 3.8 +/- 1.2 mm, p < 0.05). The systolic annular area was significantly larger in the MR group than the non-MR group. CONCLUSION: The 'saddle shape' of the mitral annulus was deformed in patients with ischemic MR. Mitral annulus deformation may play a role in ischemic MR in conjunction with mitral valve tenting. These results suggest that a non-planar saddle-shaped annuloplasty ring would contribute to successful mitral valve repair durability in patients with ischemic MR.

Aged↗
PubMed2004

Quantitative assessment of right ventricular geometric remodeling in pulmonary hypertension secondary to left-sided heart disease using real-time three-dimensional echocardiography.

We assessed right ventricular (RV) geometric remodeling quantitatively in patients with chronic pulmonary hypertension (PH) secondary to left-sided heart disease using real-time 3-dimensional echocardiography by comparing segmental and total volumes to that in normal subjects. The comparison result revealed that RV geometric remodeling in the PH group mainly occurred at the basal, mid-basal, and mid-segments. Total RV end-diastolic and end-systolic volumes in the PH group were significantly larger than that in normal subjects.

Adult↗
PubMed2004

Evaluation of abnormal motion of interventricular septum after coronary artery bypass grafting operation: assessment by ultrasonic strain rate imaging.

We investigated whether strain rate imaging by echocardiography can quantify abnormal motion of interventricular septum (IVS) after coronary artery bypass grafting operation (CABG). Strain rate imaging was performed in 12 patients with angina pectoris treated by CABG; 12 patients with angina pectoris treated medically, with catheter intervention, or both (non-CABG); and 10 patients with previous anterior myocardial infarction. Peak systolic Doppler tissue velocity of mid-IVS was significantly lower in the CABG group than in the non-CABG group (2.15 +/- 0.58 cm/s vs 3.37 +/- 1.15 cm/s; P <.05). However, there was no significant difference in peak systolic strain (PSS) rate and PSS of mid-IVS between CABG and non-CABG groups. PSS rate and PSS of mid-IVS were significantly lower in the anterior myocardial infarction group than in the non-CABG group (-0.45 +/- 0.25/s vs -1.22 +/- 0.28/s and -5.8 +/- 4.9% vs -17.2 +/- 3.4%, respectively; P <.0001). Strain rate imaging can quantify accurate left ventricular function in cases of apparently reduced cardiac motion.

Angina Pectoris↗
PubMed2004

Assessment of regional myocardial strain by a novel automated tracking system from digital image files.

Myocardial strain imaging by Doppler tissue echocardiography is a useful method to quantify regional left ventricular function. However, this method has a problem of its Doppler angle dependency. We attempted to quantify myocardial strain by a newly developed automated tracking system from digital image files. In 6 anesthetized open-chest dogs, a pair of ultrasonic crystals was implanted at the inner site and outer site of the left ventricular wall to measure myocardial radial strain. B-mode echocardiographic images and trajectories of crystals were recorded simultaneously. Three conditions were examined by intravenous infusion of dobutamine. We used a pattern matching algorithm, which allowed us to track objects from one frame to the next. In 18 image sequences obtained in the 6 dogs, there was an excellent correlation in maximal myocardial strain between the two methods ( r = 0.92, P < .0001). Thus, this system is a promising tool to provide automated quantification of regional myocardial strain.

Algorithms↗
PubMed2004

Effect of nicorandil, a K+ATP -channel opener, on coronary capillary architecture and volume after early myocardial ischemia-reperfusion--a 3-dimensional confocal laser microscopic study--.

BACKGROUND: Previous experimental and clinical studies have reported that nicorandil, an adenosine triphosphate (ATP)-sensitive K+ channel opener, exerts a beneficial effect on microvascular function and clinical outcome after myocardial ischemia. The present study assessed whether intravenous administration of nicorandil affects the 3-dimensional (3-D) architectural characteristics of capillaries and their volume after early myocardial reperfusion. METHODS AND RESULTS: Using the hearts of open-chest anesthetized rats, the left anterior descending artery was occluded for 7 min followed by reperfusion. Nicorandil or saline was infused intravenously during occlusion and reperfusion. The entire coronary microvasculature was filled with contrast medium after the hearts were arrested. Capillaries were observed 3-dimensionally by confocal laser scanning microscopy in both the control area and reperfused area of all samples. The capillary volume fraction was computed from the 3-D images. The reperfused area in both the nicorandil and saline groups showed characteristic architectural changes of the capillaries. Capillary volume fraction in the reperfused area was significantly reduced in saline group, compared with nicorandil group [12.7+/-7.2% vs 18.1 +/-5.3% (p<0.01)]. CONCLUSIONS: Intravenous nicorandil administration has a beneficial effect on capillary damage after reperfusion.

Adenosine Triphosphate↗
PubMed2004

Three-dimensional microstructural abnormality of the coronary capillary network after myocardial reperfusion--comparison between 'reflow' and 'no-reflow'.

BACKGROUND: The 3-dimensional (D) structural abnormalities of the coronary capillary network and capillary volume changes after myocardial reperfusion were investigated using confocal laser scanning microscopy. METHODS AND RESULTS: Using open-chest anesthetized rats' hearts, the left anterior descending artery (LAD) was occluded for 7 min followed by reperfusion. The hearts were divided into 2 groups: (1) reperfused area stained well by intravenous indocyanine green after reperfusion (Reflow), and (2) lack of staining in the reperfused area (No-reflow). The entire coronary microvasculature was filled with contrast medium using a Langendorff's perfusion system. Capillaries were observed 3-dimensionally in the control and reperfused areas in both the Reflow and No-reflow group and the capillary volume fraction was computed from the 3-D images. The reperfused area in both groups showed decreased capillary diameter with waving and shrinkage configuration. In the No-reflow group, marked interruption of capillary network was observed. In the Reflow group the capillary volume fraction was significantly reduced in the reperfused area compared with the control area (14.8+/-4.1% vs 22.2+/-5.6%, p<0.05). Capillary volume fraction was further decreased in the No-reflow group compared with Reflow (5.3+/-1.4% vs 14.8+/-4.1%, p<0.01). CONCLUSION: The morphological changes in coronary capillaries after reperfusion were characterized by waving and shrinkage, which resulted in a reduction in capillary volume.

Animals↗
PubMed2004

Adult case of isolated ventricular noncompaction discovered by complete atrioventricular block.

A 25-year-old male was admitted to hospital with a 3-day history of worsening faintness. The electrocardiogram showed complete atrioventricular block. Echocardiography showed generalized hypokinesis and prominent trabeculations ranged from the apex to the mid-ventricular lateral wall of the left ventricle as well. Furthermore, trabeculations in the left ventricle were seen in his sister and brother. Thus, isolated ventricular noncompaction (IVNC) was diagnosed and a permanent pacemaker was implanted. Common clinical symptoms of IVNC are heart failure, ventricular arrhythmias, and embolic events. This is the first reported adult case of IVNC disclosed by the presence of complete atrioventricular block.

Adult↗
PubMed2004

[Relationship between coronary flow reserve and recovery of regional left ventricular function in patients with tako-tsubo-like transient left ventricular dysfunction].

OBJECTIVES: This study assessed the relationship between coronary flow reserve and functional recovery of left ventricular wall motion in patients with tako-tsubo-like transient left ventricular dysfunction. METHODS: Coronary flow reserve was measured using the Doppler guide wire technique in the left descending coronary artery in nine consecutive patients (three men, six women, mean age 71 +/- 11 years) with tako-tsubo-like transient left ventricular dysfunction. Regional wall motion was analyzed to estimate anterior wall motion score index (anterior WMSI) by transthoracic echocardiography on admission and 3 weeks after the onset of symptoms. RESULTS: Anterior WMSI was 2.2 +/- 0.4 on admission and improved to 1.4 +/- 0.5 at 3 weeks later (p < 0.001). Coronary flow reserve on admission was not correlated to the anterior WMSI on admission (r = 0.19, p = 0.63). However, coronary flow reserve on admission was correlated to the improvement in anterior WMSI (r = 0.74, p = 0.02). CONCLUSIONS: Coronary microcirculation is damaged in acute phase of tako-tsubo-like transient left ventricular dysfunction. The severity of coronary microvascular dysfunction influences the degree of left ventricular wall motion recovery.

Aged↗
PubMed2004

[Mechanisms of impaired coronary flow reserve in patients with aortic stenosis: transthoracic Doppler echocardiographic study].

OBJECTIVES: Development of left ventricular hypertrophy in severe aortic stenosis is associated with coronary microcirculatory dysfunction, as demonstrated by impaired coronary flow reserve. Recently, coronary flow reserve can be assessed noninvasively by transthoracic Doppler echocardiography (TTDE). This study assessed the relationship between coronary flow reserve obtained by TTDE and the hemodynamic parameters and left ventricular mass index in patients with aortic stenosis. METHODS: Consecutive 29 patients (15 men, 14 women, mean age 72 +/- 11 years) with isolated mild to severe aortic stenosis were studied using TTDE to assess coronary flow reserve. Peak transvalvular pressure gradient across the aortic valve (peak AVG) and aortic valve area were measured by TTDE. Left ventricular mass index was measured by echocardiography. RESULTS: There were significant correlations between coronary flow reserve and peak AVG (r = -0.570, p = 0.001), left ventricular mass index (r = -0.620, p < 0.001), aortic valve area (r = 0.740, p < 0.001), and left ventricular rate pressure product (r = -0.660, p < 0.001). Multiple regression analysis showed that aortic valve area and peak AVG were independent factors for coronary flow reserve (p < 0.001, p = 0.048). CONCLUSIONS: Impairment of coronary flow reserve in patients with aortic stenosis is related to aortic valve area and peak AVG, rather than the degree of left ventricular hypertrophy.

Aged↗
PubMed2004

[Bilateral coronary ostial stenosis after aortic valve replacement with freestyle stentless bioprosthesis: a case report].

An 80-year-old woman underwent aortic valve replacement with Freestyle stentless prosthetic valve for the stenosis. Four months later, she was admitted with myocardial ischemia. Coronary angiography revealed severe stenosis in the ostium of both right and left coronary arteries. Coronary artery bypass grafting was performed. One year later, percutaneous coronary intervention was carried out for the bilateral coronary arteries because of unstable angina. Intravascular ultrasonography demonstrated localized, membranous, homogeneous, and severe stenoses in the ostium of the right and left coronary arteries. Histological examination of a specimen taken by directional coronary atherectomy showed intimal hypertrophy, mucinous degeneration, and hyaline degeneration without reactive change. There were no findings of atherosclerosis. These clinical, angiographical histological and intravascular ultrasonography findings suggest that the immunological reaction to the heterograft was the mechanism of the bilateral ostial coronary arteries stenoses in the present case. The possibility of immunological reaction after aortic valve replacement with heterograft should be considered. There have been no report on intravascular echocardiographic and histological findings.

Aged↗
PubMed2003

Prognosis of retrograde dissection from the descending to the ascending aorta.

BACKGROUND: Natural history of aortic dissection (AD) with intimal tear in the descending or abdominal aorta and retrograde extension into the ascending aorta (retrograde AD) remains unknown. The purpose of this study was to elucidate medium-term prognosis of patients with retrograde AD. METHODS AND RESULTS: Study population consisted of 109 patients with acute type A AD. There were 27 patients (25%) with retrograde AD and 82 patients (75%) with intimal tear in the ascending aorta (antegrade AD). In antegrade AD patients, 60 patients underwent surgery and 22 patients were treated medically. In retrograde AD patients, 14 patients showed localized crescentic high attenuation area along the ascending aortic wall without enhancement in computed tomography. Transesophageal echocardiography revealed complete thrombosis of false lumen (FL) in the ascending aorta (retrograde thrombosed). The remaining 13 patients showed incomplete or no thrombosis (retrograde nonthrombosed). All retrograde nonthrombosed AD patients underwent surgery except for 1 patient with stroke, whereas all retrograde thrombosed AD patients were treated medically. In-hospital mortality rate of retrograde AD patients was significantly lower than that of antegrade AD patients (15% versus 38%, P=0.027). The survival rates in retrograde AD patients were all 85% at 1, 2, and 5 years, which were significantly higher than those of antegrade AD patients (63%, 62%, and 57%, respectively)(P=0.009). CONCLUSIONS: Patients with type A retrograde AD have better medium-term prognosis than patients with antegrade AD. Retrograde AD patients with thrombosed FL in the ascending aorta could be treated medically with timed surgical repair.

Aged↗
PubMed2003

Long-term prognosis of patients with type B aortic intramural hematoma.

BACKGROUND: The long-term clinical course of patients with type B aortic intramural hematoma (IMH) and predictors for progression remains unknown. The difference of aortic pathology may have a different impact on clinical course compared with classic aortic dissection (AD). The purpose of this study was to investigate long-term clinical course and predictors of progression in patients with type B IMH. METHODS AND RESULTS: Clinical data were compared retrospectively between 53 patients with acute type B IMH (IMH group) and 57 patients with acute type B AD (AD group). All patients were treated initially with medical therapy. Two patients in IMH group and 14 patients in AD group underwent surgical repair because of aortic enlargement. The in-hospital mortality rate in IMH group was significantly lower than that in AD group (0% and 14%, P=0.006). Mean follow-up periods were 53+/-43 months, which revealed 3 and 5 late deaths, respectively. Eleven patients with IMH showed progression (development of aortic dissection or aortic enlargement) in follow-up imaging study. The actuarial survival rates in IMH group were 100%, 97%, and 97% at 1, 2, and 5 years, which were significantly higher than those in AD group (83%, 79%, and 79%) (P=0.009). Multivariate analysis identified age >70 years and new appearance of an ulcerlike projection as the strongest predictors of progression in patients with IMH. CONCLUSIONS: Patients with type B IMH have better long-term prognosis than patients with AD. Older age and appearance of an ulcerlike projection are predictive for progression in patients with type B IMH.

Aged↗
PubMed2003

Measurement of acetylcholine-induced endothelium-derived nitric oxide in aorta using a newly developed catheter-type nitric oxide sensor.

Intra-aortic measurement of nitric oxide (NO) would provide valuable insights into NO bioavailability in systemic circulation and vascular endothelial function. In the present study, we thus developed a catheter-type NO sensor to measure intra-aortic NO concentration in vivo. An NO sensor was encased and fixed in a 4-Fr catheter. The sensor was then located in the thoracic aorta via the femoral artery through a 7-Fr catheter to measure intra-aortic plasma NO concentration in vivo in anesthetized dogs. Infusion of acetylcholine (10 microg/kg) increased base-to-peak plasma NO level in the aorta by 2.4+/-0.4 nM (n=7). After 20-min infusion of N(G)-methyl-L-arginine (NO synthase inhibitor), changes in plasma NO concentration in response to acetylcholine were attenuated significantly (1.8+/-0.4 nM, P<0.003, n=7). In conclusion, the newly developed catheter-type NO sensor successfully measured acetylcholine-induced changes in intra-aortic plasma concentration of endothelium-derived NO in vivo and demonstrated applicability to direct evaluation of intravascular NO bioavailability.

Acetylcholine↗
PubMed2003

Assessment of coronary flow reserve by coronary pressure measurement: comparison with flow- or velocity-derived coronary flow reserve.

OBJECTIVES: This study sought to assess the reliability of pressure-derived coronary flow reserve (CFR) compared with flow- or velocity-derived CFR. BACKGROUND: Coronary flow reserve has been reported to have important clinical implications for the evaluation and treatment of coronary artery disease. METHODS: Using a pressure guide wire, coronary pressure distal to the stenosis was measured at rest and during hyperemia in seven dogs with various degrees of stenosis and in 30 patients with angina (29 and 34 stenoses in total, respectively). Pressure at the tip of the guiding catheter was also recorded with a fluid-filled transducer system. Pressure-derived CFR was calculated by the square root of the pressure gradient across the stenosis (DeltaP) during hyperemia divided by DeltaP at rest, using a proprietary software system. At the same time, coronary flow was monitored proximal to the stenosis with a flow meter in the experimental dogs, and coronary flow velocity distal to the stenosis was assessed using a Doppler guide wire in patients with angina. Flow-derived (or velocity-derived) CFR was compared with pressure-derived CFR. RESULTS: Except for one stenosis that showed no DeltaP at rest, a significant correlation was obtained between pressure- and flow-derived CFR in the animal study (y = 1.05x - 0.03, r = 0.92, p = 0.0001). A significant correlation was also seen between pressure- and velocity-derived CFR in the human study, except in three stenoses with no resting DeltaP (y = 0.70x + 0.37, r = 0.85, p = 0.0001). CONCLUSIONS: Similar to flow (or velocity) measurement, CFR can be assessed by pressure measurement, except in stenoses with minor resting DeltaP.

Aged↗
PubMed2003

Automated quantification of left ventricular function by the automated contour tracking method.

The automated contour tracking (ACT) method has been developed for the automated measurement of area volume using the energy minimization method without tracing a region of interest. The purpose of this study was to compare the ACT method and left ventriculography (LVG) for the measurement of left ventricular (LV) function in the clinical setting. An apical four-chamber view was visualized by two-dimensional echocardiography and recorded for off-line analysis in 14 patients with high-quality images who underwent LVG. The ACT method automatically traces the endocardial border from the recorded images and calculates LV volumes (end-diastole and end-systole) and ejection fraction (EF). Both ACT and LVG were compared by linear regression analysis for the measurement of EF. EF determined by the ACT method agreed well with that by LVG (r = 0.96, y = 0.94x + 4.6, standard error of the estimate = 3.9%). The mean difference between the ACT and LVG was -1.4%+/- 7.3%. In conclusion, the ACT method is reliable for noninvasive estimation of EF in high-quality images. This suggests that this new technique may be useful in the automated quantification of LV function.

Adult↗