Shinro Matsuo

Angiotensin-converting enzyme inhibition but not angiotensin II type 1 receptor antagonism augments coronary release of tissue plasminogen activator in hypertensive patients.

OBJECTIVESnWe compared the effects of perindopril and losartan on endothelium-dependent coronary vasomotor and fibrinolytic function.nnnBACKGROUNDnThe renin-angiotensin system regulates the vascular fibrinolytic balance. However, the effects of angiotensin-converting enzyme inhibitors and angiotensin II type 1 receptor antagonists on coronary fibrinolytic function have not been compared in hypertensive patients.nnnMETHODSnForty-five patients with hypertension were randomly assigned to three groups: 16 patients were treated with perindopril (4 mg/day) for four weeks; 15 were treated with losartan (50 mg/day) for four weeks; and 14 were not treated with either perindopril or losartan (control group). Graded doses of bradykinin (BK) (0.2, 0.6, and 2.0 microg/min) were administered into the left coronary artery. Coronary blood flow (CBF) was evaluated by Doppler flow velocity measurement.nnnRESULTSnBradykinin induced dose-dependent increases in CBF in all groups. The increases in CBF induced by BK in the perindopril and losartan groups were significantly greater than those in the control group. Net coronary tissue-type plasminogen activator (t-PA) release was enhanced by BK in all groups, and the increase in the perindopril group was greater than that in the losartan and control groups. Bradykinin did not alter plasminogen activator inhibitor type 1 levels in any of the groups.nnnCONCLUSIONSnPerindopril and losartan similarly augment BK-induced coronary vasodilation. Perindopril may have a greater potential to enhance the BK-induced coronary release of t-PA than losartan.

Left ventricular systolic/diastolic function evaluated by quantitative ECG-gated SPECT: comparison with echocardiography and plasma BNP analysis

Objective: The aim of this study was to evaluate the left ventricular (LV) functional parameters calculated using quantitative electrocardiography (ECG)-gated myocardial perfusion single photon emission computed tomography (QGS). In addition to LV systolic parameters, diastolic parameters were compared with those by ultrasound echocardiography (UCG) and also with plasma B-type natriuretic peptide (BNP) concentrations.Methods: We examined 46 patients with various forms of heart disease. By the QGS data with 16 framing data acquisition using technetium (Tc)-99m methoxyisobutylisonitrile (MIBI) perfusion, we calculated the following parameters: LV end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), peak filling rate (PFR), filling rate during the first third of the filling time ( 1/3FR) and first third filling fraction ( 1/3FF). By UCG, we measured mitral early to atrial (E/A) wave velocity ratio and pulmonary venous inflow systolic/diastolic (S/D) ratio as diastolic functional parameters. Plasma BNP concentrations were also measured.Results: There was a significant correlation between LVEDV, ESV and EF measured by QGS and UCG (EDV, r = 0.71, p < 0.001; ESV, r = 0.82, p < 0.001; EF, r = 0.75, p < 0.001). The PFR, 1/3FR and 1/3FF obtained by QGS correlated positively with E/A ratio (PFR, r = 0.54, p < 0.001; 1/3FR, r = 0.61, p < 0.001; 1/3FF, r = 0.42, p < 0.01) and negatively with S/D ratio (PFR, r = -0.40, p < 0.01; 1/3FR, r = -0.38, p < 0.05; 1/3FF, r = -0.39, p < 0.01) obtained by UCG. Plasma BNP concentrations in EF < 50% patients were greater than those in EF ≥ 50% patients (335.2 ± 60.2 vs. 101.2 ± 41.3 pg/m/, p < 0.01, both n = 17). Plasma BNP levels were also compared between higher and lower 1/3FF patients matched for LVEF. Plasma BNP concentrations in 1/3FF < 35% patients were significantly greater than those in 1/3FF ≥ 35% patients (312.9 ± 62.5 vs. 120.5 ± 32.8 pg/m/, p < 0.05, both n = 14).Conclusions: The degree of LV systolic and diastolic dysfunctions evaluated by QGS correlated with that by UCG or BNP. The QGS functional parameters offer useful information regarding cardiac failure.

Visual assessment of coronary artery stenosis with electrocardiographically-gated multislice computed tomography.

Background: With faster image acquisition times and thinner slice widths, multislice detector computed tomography (MSCT) allows visualization of human coronary arteries. Significantly improved image quality, with high resolution and new software for three-dimensional post-processing, has made non-invasive examination of the cavities within human body possible. Objective: The aims of this study are to evaluate the diagnostic accuracy of ECG-gated MSCT for the detection of significant coronary artery stenosis and occlusions. Methods: In 25 patients (19 male and 6 female aged 65 ± 9 years) with suspected obstructive coronary artery disease, ECG-gated MSCT angiography was performed with an 8-slice MSCT scanner. Visual coronary arteries were simulated in three coronary arteries. Conventional coronary angio-graphies were performed in all patients. And coronary lesions in MSCT were estimated by two observers, who did not know the results of the coronary angiography. Results: Current MSCT allows visual coronary artery with good image quality. The overall sensitivity for diagnosing significant coronary stenosis were 75.0%, the specificity was 95.6%. The positive and negative predictive values were 84.9 and 92.2%, respectively. The accuracy of MSCT for detecting coronary stenosis is the highest in the left main tranck and left anterior descending coronary artery, and lowest in the circumflex coronary artery. Conclusion: MSCT was feasible for the detection of coronary artery stenosis.

Prognostic value of ECG-gated thallium-201 single-photon emission tomography in patients with coronary artery disease.

Background: The phenomenon of reversible impairment in LV function has been well described and is known as myocardial stunning.Objective: Thallium-201 myocardial perfusion gated SPECT was used to evaluate myocardial stunning and its incremental prognostic value in patients with coronary artery disease.Patients and Methods: Fifty-six patients (aged 63 ±11 years) with coronary artery disease were included in this study. All subjects underwent exercise thallium scintigraphy. ECG-gated SPECT was obtained both at post-stress (10 minutes after the injection of 111 MBq of thallium at the time of peak exercise) and at rest (180 minutes). The left ventricular ejection fraction (LVEF) and end-systolic and end-diastolic volume (ESV, EDV) were determined by a quantitative gated SPECT (QGS) program.Results: Follow-up was complete in all patients (mean 569 days). The magnitude of the depression of post-stress LVEF relative to the rest LVEF was correlated with the severity of ischemia (p < 0.05). The group with a median LVEF of more than 45% had a significantly higher event-free rate (p < 0.01).Conclusion: Assessment of post-stress left ventricular function by gated-SPECT provides incremental prognostic information and is useful in predicting cardiac events in patients with suspected or definite coronary artery disease.

Augmentation Index and Pulse Wave Velocity as Indicators of Cardiovascular Stiffness

The authors examine the clinical significance of radial augmentation index (rAI) and brachial-ankle pulse wave velocity (baPWV). In 78 hypertensive patients, rAI correlates inversely with pulse rate (PR; r = −0.57, P < .001), but baPWV does not. A weak correlation between rAI and systolic blood pressure (SBP) is observed (r = 0.28, P < .05). rAI has no significant correlation with diastolic blood pressure (DBP). In contrast, baPWV correlates positively with both SBP (r = 0.54, P < .001) and DBP (r = 0.43, P < .001). In 56 of these patients, baPWV correlates with the diastolic parameters—the mitral E/A ratio (r = —0.35, P < .01), pulmonary vein S/D ratio (r = 0.41, P < .01), and deceleration time (r = 0.28, P < .05)—by echocardiography, but AI.P75 (rAI corrected for PR 75 bpm because of PR dependence) does not. Therefore, for detection of diastolic dysfunction, baPWV may be more sensitive than rAI.

Detection of denervated but viable myocardium in cardiac sarcoidosis with I-123 MIBG and TI-201 SPECT imaging

A 58-year-old man, who had biopsy-proven cardiac sarcoidosis, underwent Tl-201 and I-123 MIBG cardiac scintigraphy. Although no perfusion defect was identified by Tl-201, mild heterogeneity of I-123 MIBG uptake was present in the myocardium. The denervated but viable myocardium was demonstrated in the heart with sarcoidosis. Cardiac sympathetic nerve function was impaired in cardiac sarcoidosis, slightly improved with steroid therapy. I-123 MIBG scintigraphy may be useful to assess extent of myocardial involvement and response to therapy.

Impact of endothelial dysfunction on left ventricular remodeling after successful primary coronary angioplasty for acute myocardial infarction —Analysis by quantitative ECG-gated SPECT—

BackgroundWe hypothesized that endothelial cell integrity in the risk area would influence left ventricular remodeling after acute myocardial infarction.Patients and MethodsTwenty patients (61±8 y.o.) with acute myocardial infarction underwent99mTc-tetrofosmin imaging in the sub-acute phase and three months after successful primary angioplasty due to myocardial infarction. All patients were administered angiotensin-converting enzyme inhibitor after revascularization. Cardiac scintigraphies with quantitative gated SPECT were performed at the sub-acute stage and again 3 months after revascularization to evaluate left ventricular (LV) remodeling. The left ventricular ejection fraction (EF) and end-systolic and end-diastolic volume (ESV, EDV) were determined using a quantitative gated SPECT (QGS) program. Three months after myocardial infarction, all patients underwent cardiac catheterization examination with coronary endothelial function testing. Bradykinin (BK) (0.2,0.6, 2.0 μg/min) was administered via the left coronary artery in a stepwise manner. Coronary blood flow was evaluated by Doppler flow velocity measurement. Patients were divided into two groups by BK-response: a preserved endothelial function group (n= 10) and endothelial dysfunction group (n = 10).ResultsAt baseline, both global function and LV systolic and diastolic volumes were similar in both groups. However, LV ejection fraction was significantly improved in the preserved-endothelial function group, compared with that in the endothelial dysfunction group (42 ± 10% to 48 ± 9%, versus 41 ± 4% to 42 ± 13%, p < 0.05). LV volumes progressively increased in the endothelial dysfunction group compared to the preserved-endothelial function group (123 ± 45 ml to 128 ± 43 ml, versus 111 ± 47 ml to 109 ± 49 ml, p < 0.05).ConclusionIn re-perfused acute myocardial infarction, endothelial function within the risk area plays an important role with left ventricular remodeling after myocardial infarction.

Iodine-123 BMIPP scintigraphy in the evaluation of patients with heart failure.

Purpose: To investigate whether cardiac parameters obtained by I-123 15-(p-iodophenyl)-3-methyl pentadecanoic acid (BMIPP, a radioactive fatty acid analogue) myocardial scintigraphy are useful as indicators of disease severity and predictors of cardiac events in congestive heart failure (CHF). Material and Methods: Thirty-two CHF patients (functional class: 17 in NYHA II and 15 in NYHA III at the time of this study) were compared with 18 normal control subjects. Myocardial scintigraphy was performed 15u2005min and 3u2005hours after I-123 BMIPP injection. The heart-to-mediastinum count ratio of I-123 BMIPP on the initial (H/Mi) and delayed (H/Md) images and the washout rate (WR) were calculated. Results: Both H/Mi and H/Md were lower in CHF than in controls (H/Mi 1.96±0.18 vs. 2.30±0.29; H/Md 1.72±0.15 vs. 1.97±0.21; both P<0.001), but WR was higher in CHF than in controls (WR (%) 23.7±5.7 vs. 18.2±6.0, P<0.01). Both H/Mi (R = 0.42, P<0.05) and H/Md (R = 0.45, P<0.05) correlated positively with the left ventricular (LV) ejection fraction (EF), estimated by echocardiography. The WR correlated positively with the plasma B-type natriuretic peptide (BNP) level (R = 0.47, P<0.01). Kaplan-Meier analysis showed an earlier CHF progression for patients with a lower H/Mi (<1.94). Conclusion: Myocardial metabolic abnormality evaluated by I-123 BMIPP scintigraphy is related to the severity of CHF. Furthermore, it may be useful as a predictor for cardiac events.

Detection of Metabolic Abnormality in Asynergic Regions of Ischemic Human Myocardium Using 31P and 1H Magnetic Resonance Spectroscopy

To assess quantitatively phosphocreatine (PCr), adenosine triphosphate (ATP) and total creatine (CR) in asynergic regions of ischemic human myocardium using phosphorus (31P) and proton magnetic resonance spectroscopy (1H MRS). Patients were divided into two groups: 31P MRS and 1H MRS. In each group, patients were subdivided into three groups using echocardiography: a normokinetic [WN(P) (n = 6) in 31P MRS, WN(H) (n = 10) in 1H MRS], a hypokinetic [WH(P) (n = 13), WH(H) (n = 7)], and a- or dyskinetic wall motion groups [WA(P) (n = 14), WA(H) (n =6)]. They were compared with normal subjects of each group [CNP (n = 10), CN(H) (n = 10)]. 31P MRS spectra were obtained from the anterior and apical regions of the left ventricle by slice-selected 1D CSI. 1H MRS spectra were obtained from the 2 x 2 x 2-cm voxel set in the left ventricular wall by the PRESS method. In the 31P MRS group, myocardial PCr was significantly lower in the WH(P) and WA(P) groups than in the CN(P) group, but myocardial PCr in the WN(P) group did not differ from that in CN(P). A difference in ATP could not be detected among the four groups. In the 1H MRS group, myocardial CR was significantly lower in the WH(H) and WA(H) groups than in the CN(H) group. Myocardial CR in the WNH group did not differ from that in the CN(H). The noninvasive 31P and 1H MRS approach is useful in the assessment of metabolite reduction associated with wall motion abnormality.

Creatine depletion and altered fatty acid metabolism in diseased human hearts : Clinical investigation using 1H magnetic resonance spectroscopy and 123I BMIPP myocardial scintigraphy

Background: In the heart, the creatine kinase system plays an important role in energy reserves, and myocardial energy production essentially depends upon fatty acid metabolism. Purpose: To examine myocardial creatine (CR) concentration and altered cardiac fatty acid metabolism in various forms of heart disease. Material and Methods: Myocardial CR concentration of the septum was measured by gated 1H magnetic resonance spectroscopy (MRS), applying a point-resolved spectroscopy (PRESS) sequence in 34 patients with heart disease. Of these patients, 14 underwent 123I BMIPP (radioactive fatty acid analogue) myocardial scintigraphy to evaluate myocardial fatty acid metabolism. Cardiac 123I BMIPP uptake was calculated as the heart-to-mediastinum count ratio. Results: Myocardial CR concentration correlated positively with the left ventricular ejection fraction (LVEF) by echocardiography (R = 0.61, P<0.001, n = 34), suggesting that the degree of reduced CR is related to the severity of contractile dysfunction. Cardiac 123I BMIPP uptake also correlated positively with LVEF (initial image, R = 0.60, P<0.05; delayed image, R = 0.63, P<0.05; n = 14). There was a significant correlation between myocardial CR and cardiac 123I BMIPP uptake (initial image, R = 0.77, P<0.01; delayed image, R = 0.82, P<0.001; n = 14). Conclusion: Our study suggests an association between CR depletion and impaired fatty acid metabolism in various forms of heart diseases.