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Biomedical subjects

Atsushi Yamamuro

Publications and source records attributed to Atsushi Yamamuro.

17 recordsLinked to original sources
PubMed2006

Coronary flow velocity pattern assessed noninvasively by transthoracic color Doppler echocardiography serves as a predictor of adverse cardiac events and left ventricular remodeling in patients with acute myocardial infarction.

BACKGROUND: Quantitative assessment of microvascular injury is possible in patients with reperfused anterior myocardial infarction by invasive method. Coronary flow velocity patterns can also be assessed by transthoracic color Doppler echocardiography (TTCDE). OBJECTIVES: The purpose of this study was to determine whether the coronary flow velocity pattern assessed by TTCDE serves as a predictor of adverse cardiac events and left ventricular remodeling. METHODS: The study population consisted of 64 consecutive patients. We could analyze coronary flow velocity patterns by TTCDE in 59 of 64 patients (92%) after coronary intervention. The patients were followed up for the occurrence of complications and underwent serial measurement of left ventricular volumes. RESULTS: In patients with a short deceleration time of diastolic flow velocity, the frequency of adverse cardiac events and left ventricular remodeling was higher. CONCLUSION: It is possible to predict clinical outcome by assessing coronary flow velocity pattern by TTCDE.

Blood Flow Velocity↗
PubMed2005

Annular geometry in patients with chronic ischemic mitral regurgitation: three-dimensional magnetic resonance imaging study.

BACKGROUND: Although animal studies showed that annular remodeling may be related to the pathogenesis of chronic ischemic mitral regurgitation (CIMR), little was known in humans. A better understanding of the precise 3D geometry of the mitral valvular-ventricular complex in CIMR is needed to devise a better surgical technique. The purpose of the study was to elucidate mitral annular geometry in patients with CIMR using cardiac MRI. METHODS AND RESULTS: Thirty-eight patients with previous inferior or posterior myocardial infarction were studied. With the 3D reconstruction of the mitral annulus and subvalvular apparatus from a series of longitudinal cine MRIs, end-systolic mitral annulus dimensions and 3D geometry were calculated. Patients were grouped by mitral regurgitation grade using echocardiography (> or =2+, n=15 versus < or =1+, n=23). Both septal-lateral and commissure-commissure mitral annular diameters were significantly greater in CIMR(+) patients (35+/-5 versus 30+/-4 mm, P=0.005; 46+/-6 versus 39+/-4 mm, P<0.001, respectively). The length of the fibrous annulus was significantly larger in CIMR(+) patients (28+/-3 versus 24+/-3 mm; P<0.001). The height of the annular "saddle horn" above a best-fit plane was lower in CIMR(+) patients (4.2+/-1.2 versus 6.0+/-1.8 mm; P=0.002), and the annular height to commissural width ratio was significantly lower in CIMR(+) patients (12+/-3 versus 21+/-5%; P<0.001). CONCLUSIONS: Patients with CIMR had greater septal-lateral and commissure-commissure mitral annular dimension, larger intertrigonal distance, and flattened saddle shape of mitral annulus. These associated geometric alterations may be important in the pathogenesis of CIMR.

Adult↗
PubMed2005

Quantitative assessment of harmonic power doppler myocardial perfusion imaging with intravenous Levovist in patients with myocardial infarction: comparison with myocardial viability evaluated by coronary flow reserve and coronary flow pattern of infarct-related artery.

BACKGROUND: Myocardial contrast echocardiography and coronary flow velocity pattern with a rapid diastolic deceleration time after percutaneous coronary intervention has been reported to be useful in assessing microvascular damage in patients with acute myocardial infarction. AIM: To evaluate myocardial contrast echocardiography with harmonic power Doppler imaging, coronary flow velocity reserve and coronary artery flow pattern in predicting functional recovery by using transthoracic echocardiography. METHODS: Thirty patients with anterior acute myocardial infarction underwent myocardial contrast echocardiography at rest and during hyperemia and were quantitatively analyzed by the peak color pixel intensity ratio of the risk area to the control area (PIR). Coronary flow pattern was measured using transthoracic echocardiography in the distal portion of left anterior descending artery within 24 hours after recanalization and we assessed deceleration time of diastolic flow velocity. Coronary flow velocity reserve was calculated two weeks after acute myocardial infarction. Left ventricular end-diastolic volumes and ejection fraction by angiography were computed. RESULTS: Pts were divided into 2 groups according to the deceleration time of coronary artery flow pattern (Group A; 20 pts with deceleration time > or = 600 msec, Group B; 10 pts with deceleration time < 600 msec). In acute phase, there were no significant differences in left ventricular end-diastolic volume and ejection fraction (Left ventricular end-diastolic volume 112 +/- 33 vs. 146 +/- 38 ml, ejection fraction 50 +/- 7 vs. 45 +/- 9 %; group A vs. B). However, left ventricular end-diastolic volume in Group B was significantly larger than that in Group A (192 +/- 39 vs. 114 +/- 30 ml, p < 0.01), and ejection fraction in Group B was significantly lower than that in Group A (39 +/- 9 vs. 52 +/- 7%, p < 0.01) at 6 months. PIR and coronary flow velocity reserve of Group A were higher than Group B (PIR, at rest: 0.668 +/- 0.178 vs. 0.248 +/- 0.015, p < 0.0001: during hyperemia 0.725 +/- 0.194 vs. 0.295 +/- 0.107, p < 0.0001; coronary flow velocity reserve, 2.60 +/- 0.80 vs. 1.31 +/- 0.29, p = 0.0002, respectively). CONCLUSION: The preserved microvasculature detecting by myocardial contrast echocardiography and coronary flow velocity reserve is related to functional recovery after acute myocardial infarction.

Blood Flow Velocity↗
PubMed2005

Transthoracic Doppler echocardiographic assessment of coronary flow velocity pattern in patient with acute myocardial infarction implies progression of myocardial damage.

BACKGROUND: Coronary flow velocity (CFV) pattern with a rapid deceleration time of diastolic flow velocity and small average systolic peak velocity immediately after reperfusion implies poor wall-motion recovery in patients with acute myocardial infarction. Microvascular injury has been demonstrated to progress after coronary reperfusion. The purpose of this study was to assess whether CFV 1 day after reperfusion (day 1) may reflect accurately the degree of myocardial damage. METHODS: In the left anterior descending coronary artery in 29 patients with anterior acute myocardial infarction, CFV was measured immediately and 1 day after recanalization using transthoracic Doppler echocardiography, respectively. Regional wall motion was estimated as anterior wall-motion score index (AWMSI) by echocardiography before recanalization and 1 month after the onset of acute myocardial infarction. RESULTS: Although significant correlation was observed among deceleration time of diastolic flow velocity, average systolic peak velocity, and average peak velocity immediately after reperfusion and 1-month AWMSI (r = -0.62, P < .001; r = -0.61, P < .001; and r = -0.55, P < .01, respectively), much better correlation was demonstrated between those at day 1 and 1-month AWMSI (r = -0.72, P < .0001; r = -0.68, P < .0001; and r = -0.60, P < .001, respectively). Deceleration time of diastolic flow velocity, average systolic peak velocity, and average peak velocity in poor wall-motion recovery group (1-month AWMSI > 2.0, n = 14) were significantly smaller (P < .01, P < .05, and P < .05, respectively) at day 1 compared with those immediately after reperfusion. CONCLUSIONS: CFV pattern assessed by transthoracic Doppler echocardiography at day 1 provides the degree of myocardial damage much more accurately than that immediately after reperfusion. These results may suggest that myocardial damage progresses after reperfusion.

Blood Flow Velocity↗
PubMed2005

Thiazolidinedione treatment attenuates diffuse neointimal hyperplasia in restenotic lesions after coronary stent implantation in type 2 diabetic patients: an intravascular ultrasound study.

OBJECTIVES: Thiazolidinedione treatment reduces neointimal tissue proliferation after coronary stent implantation in diabetic patients. However, in-stent restenosis still persists in patients treated with thiazolidinedione. The effect of thiazolidinedione treatment on the pattern of in-stent restenosis remains unclear. This study investigated whether thiazolidinedione treatment attenuates diffuse neointimal hyperplasia in restenotic lesions after coronary stent implantation in diabetic patients. METHODS: Volumetric intravascular ultrasound was performed at 6 months after coronary stent implantation in 76 patients with restenotic lesions who received either conventional anti-diabetic treatment (control group, n = 56) or thiazolidinedione treatment (thiazolidinedione group, n = 20). RESULTS: There were no significant differences between the two groups in stent volume (99 +/- 32 vs 90 +/- 20 mm3, respectively, p = 0.26) or in minimal lumen area in the stent (1.4 +/- 0.6 vs 1.6 +/- 0.5 mm2, respectively, p = 0.11). However, there were significant reductions in neointimal volume (56 +/- 25 vs 36 +/- 11 mm3, respectively, p < 0.01)and neointimal index (56 +/- 11% vs 41 +/- 8%, respectively, p < 0.01) in the thiazolidinedione group. Coefficient of variation of neointimal tissue accumulation was greater in the thiazolidinedione group (45.5%) than in the control group (25.2%). CONCLUSIONS: Intravascular ultrasound study demonstrated that together with reduction of overall neointimal tissue proliferation, thiazolidinedione treatment caused greater point-to-point heterogeneity in the neointimal tissue accumulation in restenotic lesions after coronary stent implantation. This finding strongly suggests that thiazolidinedione treatment attenuates diffuse in-stent restenosis in diabetic patients.

Aged↗
PubMed2004

Left atrial volume and the risk of paroxysmal atrial fibrillation in patients with hypertrophic cardiomyopathy.

Paroxysmal atrial fibrillation (PAF) is a common complication of patients with hypertrophic cardiomyopathy, often leading to acute or progressive heart failure and cerebral infarction. We assessed the echocardiographic data of 141 consecutive patients with hypertrophic cardiomyopathy, with and without PAF. In all, 31 patients (22%) had a history of PAF with spontaneous conversion to in sinus rhythm. Left atrial volume and left atrial volume indexed to body surface area were significantly increased for patients with PAF compared with those without PAF. Maximum left atrial volume was the most sensitive and specific parameter for the occurrence of PAF in patients with hypertrophic cardiomyopathy.

Atrial Fibrillation↗
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

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

Pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus: an intravascular ultrasound scanning study.

BACKGROUND: It has been reported that pioglitazone reduces neointimal hyperplasia after balloon-induced vascular injury in an experimental model. METHODS: To determine whether pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus, we studied 44 stented lesions in 44 patients with diabetes mellitus who underwent successful coronary stent implantation. Study patients were randomized into 2 groups: the pioglitazone group (23 patients with 23 lesions) and the control group (21 patients with 21 lesions). All patients underwent serial quantitative coronary angiography and serial intravascular ultrasound scanning studies. With a motorized pullback system, multiple image slices within the stent were obtained at every 1 mm. The stent area and lumen area were measured, and the neointimal area was calculated. Measurements were averaged over the number of selected image slices. The neointimal index was calculated as the averaged neointimal area divided by the averaged stent area multiplied by 100 (%). RESULTS: After 6 months of treatment, angiographic in-stent restenosis (17% vs 43%, respectively, P =.0994) and target lesion revascularization (13% vs 38%, respectively, P =.0835) were less frequent in the pioglitazone group than the control group; however, these differences did not reach significance. The intravascular ultrasound scanning study demonstrated that the neointimal index in the pioglitazone group was significantly smaller than that in the control group (28% +/- 9% vs 48% +/- 15%, respectively, P <.0001). CONCLUSION: A serial intravascular ultrasound scanning assessment demonstrated that pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus.

Aged↗
PubMed2003

Noninvasive assessment of flow velocity and flow velocity reserve in the right gastroepiploic artery graft by transcutaneous Doppler echocardiography: comparison with an invasive technique.

BACKGROUND: The measurement of flow velocity (FV) in coronary artery bypass grafts using a Doppler guidewire has provided useful clinical and physiologic information. The recently developed transcutaneous Doppler echocardiography is a noninvasive technique to measure FV and FV reserve (FVR) in the right gastroepiploic artery (GEA) graft. The purpose of this study was to evaluate whether transcutaneous Doppler echocardiography accurately measures FV and FVR in the right GEA graft in a clinical setting. METHODS: In 33 patients who underwent graft angiography for the assessment of the right GEA graft, FV in the right GEA graft was measured by transcutaneous Doppler echocardiography under the guidance of color flow Doppler imaging at the time of examination using a Doppler guidewire. FV in the midportion of the right GEA graft was measured at baseline and during hyperemic conditions using both transcutaneous Doppler echocardiography and a Doppler guidewire. RESULTS: There were excellent correlations between the value of FV obtained by transcutaneous Doppler echocardiography and those obtained with the Doppler guidewire (averaged peak velocity: y = 0.95 x + 1.46, r = 0.98, standard error of the estimate [SEE] = 2.94 cm/s; averaged systolic peak velocity: y = 0.94 x + 1.18, r = 0.97, SEE = 3.15 cm/s; diastolic peak velocity: y = 0.97 x + 1.62, r = 0.98, SEE = 4.40 cm/s; averaged diastolic peak velocity: y = 0.95 x + 1.75, r = 0.98, SEE = 3.60 cm/s). The FVR as determined by transcutaneous Doppler echocardiography showed a good correlation with that determined using the Doppler guidewire method (y = 0.90 x + 0.21, r = 0.92, SEE = 0.31). CONCLUSIONS: Transcutaneous Doppler echocardiography proved to be an accurate noninvasive method to measure FV and FVR in the right GEA graft.

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↗
PubMed2002

Coronary flow velocity pattern immediately after percutaneous coronary intervention as a predictor of complications and in-hospital survival after acute myocardial infarction.

BACKGROUND: Recently, it was reported that the degree of microvascular injury and left ventricular functional recovery during the chronic period can be predicted after treatment of the infarct-related artery based on the coronary flow velocity (CFV) pattern assessed using a Doppler guidewire. The aim of this prospective study was to examine whether the CFV pattern may predict complications and in-hospital survival after acute myocardial infarction (AMI). METHODS AND RESULTS: The study population consisted of 169 consecutive patients with a first anterior AMI successfully treated with percutaneous coronary intervention (PCI). We examined the CFV pattern immediately after PCI using a Doppler guidewire. In accordance with previous findings, we defined severe microvascular injury as a diastolic deceleration time < or =600 ms and the presence of systolic flow reversal. Patients were divided into two groups: those without severe microvascular injury (n=118; group 1) and those with severe microvascular injury (n=51; group 2). All of the patients who had cardiac rupture were in group 2. Congestive heart failure (CHF) was observed more frequently in group 2 than in group 1 (53% versus 8%, P<0.001). The in-hospital cardiac mortality rate was significantly higher in group 2 than in group 1 (18% versus 0%, P<0.001). Nine patients in group 2 died, 5 patients because of CHF and 4 patients because of cardiac rupture. CONCLUSIONS: These findings suggest that the CFV pattern is an accurate predictor of the presence or absence of complications and of in-hospital survival after AMI.

Angioplasty, Balloon, Coronary↗
PubMed2002

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

BACKGROUND: Recent studies have shown an favorable short-term prognosis of patients with type A acute aortic intramural hematoma (IMH). 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 elucidate clinical features and long-term prognosis of patients with type A IMH. METHODS AND RESULTS: Clinical data were compared retrospectively between 30 patients with acute type A IMH (IMH group) and 101 patients with acute type A AD (AD group) who were admitted to our institutions from 1988 to 1998. In AD group, 72 patients underwent surgical repair and 29 patients were treated medically. All patients in IMH group were treated initially with supportive medical therapy. Thirteen patients who demonstrated progression to AD or increase in size of hematoma underwent timed surgical repair except for 1 patient. The overall in-hospital mortality rate in IMH group was significantly lower than that in AD group (7% and 34%, P=0.004). Follow-up periods were 56+/-37 (IMH group) and 60+/-42 months (AD group), which revealed 1 and 6 late deaths, respectively. The actuarial survival rates in IMH group were all 90% at 1, 2, and 5 years, which were significantly higher than those in AD group (67%, 66%, and 62%, respectively; P=0.004). CONCLUSIONS: Patients with type A IMH have better long-term prognosis than patients with AD.

Aged↗
PubMed2002

Effects of microvascular dysfunction on myocardial fractional flow reserve after percutaneous coronary intervention in patients with acute myocardial infarction.

Fractional flow reserve (FFR) has emerged as a lesion-specific index of the functional severity of coronary stenosis in patients with chronic coronary artery disease. As the coronary blood flow in acute myocardial infarction (AMI) patients with microvascular damage is restricted, the pressure drop across the stenosis during hyperemia may be smaller than expected. However, the effects of microvascular dysfunction on FFR in AMI patients remain undetermined. The study comprised 33 AMI patients who underwent coronary stenting within 12 hr of onset, and 15 patients with stable angina pectoris who underwent elective stenting. Assessment of the 48 lesions by means of intravascular ultrasound and pressure measurements after stenting showed that postinterventional FFR was higher in AMI than angina pectoris patients (0.95 +/- 0.04 vs. 0.90 +/- 0.04; P = 0.002), although there were no significant differences in intravascular ultrasound parameters. AMI patients were divided into two subgroups based on their postprocedural Thrombolysis on Myocardial Infarction (TIMI) flow grade (23 patients with TIMI 3 and 10 with TIMI 2). There were no differences in intravascular ultrasound parameters between the AMI subgroups, while FFR was greater in the patients with TIMI 2 than in those with TIMI 3 (0.98 +/- 0.02 vs. 0.93 +/- 0.05; P = 0.017). No significant correlation was found between FFR and intravascular ultrasound parameters in either AMI subgroup, while FFR of more than 0.94 was observed in all TIMI 2 cases independent of residual stenosis severity. We conclude that in patients with marked microvascular dysfunction, FFR may not be reliable for the assessment of coronary lesion severity and may underestimate coronary lesion severity.

Aged↗
PubMedDate not supplied

Impact of insulin resistance on neointimal tissue proliferation after coronary stent implantation. Intravascular ultrasound studies.

Serial intravascular ultrasound (IVUS) studies in 55 nondiabetic patients showed that neointimal tissue proliferation after stent implantation in patients with impaired glucose tolerance (IGT) was greater than that in patients with normal glucose tolerance at follow-up. Multiple regression analysis showed that the sum of insulin levels was the best predictor of the greater neointimal index at follow-up. Another group of serial IVUS studies were performed in 62 stented lesions in 52 patients with Type 2 diabetes mellitus (DM). The study patients were randomized into a troglitazone group and a control group. The neointimal tissue proliferation at follow-up in the troglitazone group was significantly smaller than that in the control group.

Blood Glucose↗