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Biomedical subjects

K Mizushige

Publications and source records attributed to K Mizushige.

At least 55 records · Page 3Linked to original sources
PubMed2000

Sensitive detection of myocardial contraction abnormality in chronic hemodialysis patients by ultrasonic tissue characterization with integrated backscatter.

Since acoustic properties of the myocardium are sensitive to the myocardial structure and the contractile conditions of myocyte, the authors evaluated cardiac dysfunction based on the integrated ultrasonic backscatter in 18 hemodialysis (HD) patients (duration: 102 +/- 84 months, mean age: 57.6 +/- 9.7 years) and 11 age-matched normals. The cyclic variation of integrated backscatter (CV-IB) at interventricular septum (IVS) and left ventricular posterior wall (PW) was measured and compared with percent fractional shortening (%FS) and percent wall thickening (%Th). The CV-IB of HD patients was smaller than that of control subjects (IVS: 6.2 +/- 1.1 dB vs 8.2 +/- 1.1 dB, p = 0.0003 and PW: 8.4 +/- 2.2 vs 10.3 +/- 1.3, p= 0.025). No significant difference was observed in %FS and %Th between HD patients and control subjects. In HD, the ratio of velocities of early diastolic inflow (E) to late atrial inflow was decreased (0.7 +/- 0.2 vs 1.1 +/- 0.7, p = 0.049) and deceleration time of E was prolonged significantly (200 +/- 28 msec vs 159 +/- 30 msec, p = 0.0082). In the absence of overt cardiac systolic dysfunction, myocardial damage indicated as a decrease in CV-IB and diastolic dysfunction identified on transmitral velocity waveform were detected, which may reflect from the myocardial fibrosis. As a mechanism, pressure overload, hyperparathyroidism, and anemia were neglected, and the other humoral factors may contribute to the myocardial damage in chronic renal failure.

Aged↗
PubMed2000

Evaluation of effective aortic regurgitant orifice area and its effect on aortic regurgitant volume with Doppler echocardiography.

The authors measured the aortic regurgitant orifice area (ROA) using Doppler echocardiography and attempted to clarify how important the ROA is in determining the regurgitant volume (RV) in 22 patients with chronic aortic regurgitation (AR). The RV was calculated from the difference between the left ventricular ejection flow volume and transmitral inflow volume as measured by Doppler echocardiography. The ROA was obtained by two methods: RV/time velocity integral of AR jet measured by continuous wave Doppler (calculation method) and manual tracing of minimum cross-sectional area of short-axis color Doppler. The RV ranged from 10 to 90 mL/beat and the ROA by calculation method was from 0.05 to 0.35 cm2, which showed a strong correlation (r = 0.93, p < 0.001). The time velocity integral of aortic regurgitant jet showed a poor correlation with the RV (r = 0.45, p < 0.05). The values of ROA by the two methods showed a good correlation (r = 0.93, p < 0.001). Thus, the authors conclude that the ROA is a basic determinant of the RV in AR and that color Doppler can be employed to precisely assess the ROA.

Adult↗
PubMed2000

Effects of perindopril on left ventricular remodeling and aortic regurgitation in rats assessed by echocardiography.

This study investigated the effect of the angiotensin-converting enzyme (ACE) inhibitor perindopril on left ventricular (LV) remodeling and cardiac function in rats with aortic regurgitation (AR). Twenty male Sprague-Dawley rats in which AR was produced by closed-chest aortic valve puncture were divided into untreated and perindopril-treated (5 mg/kg/day) rats. Ten control rats were sham-operated. Blood pressure, body weight, and echocardiographic recordings were followed every 2 weeks for a period of 12 weeks. LV dimension (LVD) and fractional shortening (FS) were calculated. The heart was finally excised for weight, hydroxyproline measurements, and histopathology. At 12 weeks, end-diastolic LVD increased in untreated rats (10.8 +/- 0.2 mm) but did not dilate in treated rats (9.6 +/- 0.3 mm, p < 0.01 vs untreated rats). FS decreased from 6 weeks in untreated rats (27.3 +/- 0.9% at 12 weeks), but did not change in treated rats (33.8 +/- 0.5%, p < 0.001). The ratio of LV weight to body weight in untreated rats (2.62 +/- 0.11 mg/g, p < 0.05) was higher than in sham-operated rats (1.52 +/- 0.02 mg/g) and than in treated rats (1.95 +/- 0.07 mg/g). Interstitial collagen accumulation histopathologically increased in untreated rats and was inhibited in treated rats. LV collagen of untreated rats (1.46 +/- 0.08 mg/100 mg, p = 0.03) was higher than those of treated (1.08 +/- 0.09 mg/100 mg) and sham-operated rats (1.06 +/- 0.14 mg/100 mg). Perindopril inhibited LV remodeling induced by volume overload and preserved LV function in AR rats.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

Echocardiographic observation of acute myocarditis with systemic lupus erythematosus.

Although myocarditis from a series of autopsies of patients with systemic lupus erythematosus was frequently observed, the incidence of clinically apparent myocardial dysfunction was low. A 30-year-old woman with systemic lupus erythematosus was examined by echocardiography. An acoustic densitometry was followed at the left ventricular posterior wall throughout the clinical course. A decrease in the magnitude of cyclic variation of integrated backscatter (IB) was observed before treatment. Following the combined treatment, steroid and cyclophosphamide, a repeated ultrasonic tissue characterization showed an increase in the magnitude of cyclic variation of IB. It is thought that ultrasonic tissue characterization may be a useful method to evaluate the impairment of contraction, and to follow up the clinical course of myocardial involvement in systemic lupus erythematosus.

Adult↗
PubMed2000

Degos' disease with constrictive pericarditis: a case report.

A 47-year-old man with Degos' disease was examined by echocardiography, which showed hypokinesis of the apical left ventricular wall with pericardial effusion. To evaluate the myocardial perfusion and coronary flow reserve, 201Tl scintigraphy and intracoronary Doppler flowmetry were performed. The coronary flow reserve was not decreased nor was there angiographical coronary stenosis, although a pressure study revealed constrictive dysfunction of both ventricles. The constrictive pericarditis might have been induced by pericardial vasculitis, thereby causing the left ventricular wall motion abnormality.

Humans↗
PubMed2000

Transesophageal echocardiographic observation of multiple myeloma involving the pericardium: a case report.

This report presents a case of multiple myeloma with a mass lesion on the pericardium and pericardial effusion. The response to intrapericardial combination chemotherapy (cisplatin and betamethasone) was evaluated by repeated transesophageal echocardiograms. Following the treatment, complete resolution of the tumor and effusion were observed for 6 months after which the patient died of bacterial pneumonia. Intrapericardial combination chemotherapy can be an effective treatment for myelomatous involvement of the pericardium.

Aged↗
PubMed2000

Effects of valsartan on angiotensin II-induced migration of human coronary artery smooth muscle cells.

The migration as well as proliferation of coronary artery medial smooth muscle cells (SMC) into the intima is proposed to be an important process of intimal thickening in coronary atherosclerosis. In the current study, we examined the effects of the angiotensin type 1 receptor antagonist valsartan on angiotensin II (Ang II)-induced migration of cultured human coronary artery SMC using Boyden's chamber methods. Ang II significantly stimulated human coronary artery SMC migration in a concentration-dependent manner between 10(-6) and 10(-8) mol/l when cells of passage 4 to 6 were used. However, the migration response to Ang II was moderately decreased in cells of passage 10 to 12, and was markedly decreased in cells of passage 15 to 17, compared to that of passage 4 to 6. Ang II-induced migration was blocked by the Ang II type 1 (AT1) receptor antagonist valsartan in a concentration-dependent manner. By contrast, the Ang II type 2 (AT2) receptor antagonist PD 123319 did not affect Ang II-induced migration. Ang II modestly increased the cell number of human coronary artery SMC after a 24-h incubation. This increase in cell numbers was also clearly blocked by valsartan, but not by PD 123319. These results indicate that Ang II stimulates migration as well as proliferation via AT1 receptors in human coronary artery SMC when cells of passage 4 to 6 are used. Valsartan may prevent the progression of coronary atherosclerosis through an inhibition of Ang II-induced migration and proliferation in these cells, although in vivo evidence is lacking.

Angiotensin II↗
PubMed1999

Quantitative evaluation of left ventricular regional wall motion using a real-time wall thickness curve system with two-dimensional echocardiography.

The real-time wall thickness curve system was newly developed for recording left ventricular (LV) wall thickening (WT) on a 2-dimensional echocardiogram recorded in an arbitrary direction because of the scarcity of quantitative data on wall motion change during dobutamine-induced ischemia. This study tested the feasibility of this system for quantitative evaluation of wall motion. In normal subjects, accuracy and reproducibility of measurements were evaluated by comparison with measurements on a conventional M-mode echocardiogram and examination of inter- and intraobserver variability. In 28 patients with coronary artery disease, percent systolic wall thickening (%WT) was measured during dobutamine infusion in incremental doses of 6 microg/kg/min, from 6 to 30 microg/kg/min. Percent change in %WT by dobutamine was compared with percent coronary stenosis derived from quantitative coronary angiography. Analysis of the mean difference and 95% confidence intervals demonstrated good accuracy and reproducibility: 0.0 mm and intervals of -0.5 to 0.5 mm in diastolic wall thickening of LV posterior wall (PW) between both methods, -1% and -4% to 2% in %WT of IVS and LVPW between both observers, and -1% and -3% to 2% in that between both measurements. During dobutamine infusion, the percent change in %WT was significantly correlated with percent stenosis (r = 0.75, p<0.0001). The WT curve system enabled us to assess regional wall function as %WT and was available for quantitative observation of wall motion change during pharmacologic intervention. This system may reduce the effects of heart movement and may be of great clinical benefit in evaluating regional wall function.

Aged↗
PubMed1999

Feasibility of right ventricular myocardial opacification by contrast echocardiography and comparison with left ventricular intensity.

To demonstrate the feasibility and quantify the intensity of right ventricular (RV) myocardial opacification by myocardial contrast echocardiography (MCE), we analyzed MCE produced by intravenous injection of 0.15 ml/kg of QW7437 in 8 closed-chest dogs. MCE could produce visual opacification of the RV wall similar in time course to that of the left ventricular wall, and the data supported the potential role of MCE in evaluating RV hypertrophy, contraction, and perfusion abnormalities.

Animals↗
PubMed1999

Effect of batroxobin on spontaneous echo contrast and hemorheology in left atrial appendage in atrial fibrillation assessed by transesophageal echocardiograpy.

Controversy exists regarding the effect of defibrination on spontaneous echo contrast and flow dynamics in left atrial appendage (LAA) in atrial fibrillation. We aimed to investigate the effect of batroxobin, which decreases plasma fibrinogen level, on the echo intensity of spontaneous echo contrast in LAA. In 36 patients with atrial fibrillation (duration 7 +/- 4 years), transesophageal echocardiography was performed at baseline and 24 hours after batroxobin administration (0.2 U/kg). At the orifice of the LAA, integrated backscatter of echo contrast and peak velocity of LAA emptying flow were measured. Plasma fibrinogen and whole blood viscosity were also measured. Fibrinogen and viscosity were significantly lower after batroxobin administration (96 +/-38 mg/dl and 4.35 +/- 0.56 cp) than those at baseline (320 +/- 61 mg/dl and 4.71 +/- 0.61 cp, both p <0.001). A significant positive correlation between changes in plasma fibrinogen and whole blood viscosity (r = 0.49, p = 0.002) was shown. The integrated backscatter significantly decreased from 14 +/- 3 to 12 +/- 3 decibels after batroxobin (p <0.001), and the changes in integrated backscatter and plasma fibrinogen was significantly correlated. Therefore, batroxobin administration improved blood rheology and decreased blood cell aggregation, which are effective in preventing left atrial thrombus formation.

Aged↗
PubMed1999

Induced hypertension treatment to improve cerebral ischemic injury after transient forebrain ischemia.

The effect of induced hypertension treatment on cerebral ischemia is still controversial. We investigated the preferred blood pressure manipulation level and pressor agent required to reduce cerebral ischemic injury following transient forebrain ischemia induced by bilateral occlusion of the common carotid arteries in anesthetized gerbils. Following 60-min cerebral ischemia, we evaluated the preferred blood pressure manipulation level and pressor agent required to treat cerebral ischemic injury after reperfusion by examining the effects of different levels of mean arterial blood pressure (MABP), increased with phenylephrine or angiotensin II or decreased by blood withdrawal, on cerebral blood flow (CBF), survival ratio, cerebral edema, and brain energy metabolism following transient forebrain ischemia in gerbils. Mild phenylephrine-induced hypertension treatment (21+/-4 mmHg) during post-cerebral ischemia-reperfusion improved the survival ratio and reduced cerebral edema, which was also associated with an increase in local CBF and a recovery of brain energy metabolism. However, intense phenylephrine-induced hypertension, angiotensin II-induced hypertension, or hypotension worsen the survival rate and produced extra cerebral edema, that were also associated with deterioration of brain energy metabolism. These results demonstrate that a mild induced hypertension with phenylephrine (21+/-4 mmHg above the baseline level) results in reduction of the cerebral edema and improves the survival ratio and brain energy metabolism. Furthermore, angiotensin II may have neurotoxic effect to use as the pressor agent for induced hypertension after cerebral ischemia.

Adenosine Triphosphate↗
PubMed1999

Quantitative analysis of myocardial response to dobutamine by measurement of left ventricular wall motion using omnidirectional M-mode echocardiography.

Although dobutamine stress echocardiography is important for assessing cardiac ischemia and viability, analysis of wall motion is qualitatively performed. We quantitatively evaluated left ventricular wall motion using a newly developed omnidirectional M-mode echocardiography that can depict the M-mode at the site of region of interest on the 2-dimensional image in real time, and established its usefulness for analyzing the myocardial response to dobutamine infusion. Dobutamine stress echocardiography with omnidirectional M-mode was performed in 57 patients with coronary lesions. In 38 of these patients, exercise stress single-photon emission computed tomographic thallium scintigraphy (Tl-201 SPECT) was performed. Endocardial excursion of 103 regions was measured from omnidirectional M-mode at baseline, low-dose (6 microg/kg/min), and at peak dose (30 microg/kg/min) dobutamine. A decrease and increase in wall excursion was scored (from -3 to 3) for a changes of every 2 mm, and a quantitative wall motion score (QWMS) was calculated as a summation of the scores from baseline to low dose and from low to peak doses. Quantitative coronary stenosis score (QCSS) was calculated as a summation of stenotic and collateral scores. The stenosis scores were graded as: 1 = 0% to 50%, 2 = 50% to 75%, 3 = 75% to 90%, 4 = 90% to 95%, 5 = 95% to 100%; collateral scores were graded as: -1 = poor collateral, -2 = good collateral. Based on the QWMS at each dose of dobutamine, the serial changes in wall motion were divided into 4 groups: augmented, biphasic, no change, and worsening. The QCSS was clearly different among these groups. QWMS was significantly correlated with QCSS (r = 0.657, p <0.001). The incidence of redistribution in Tl-201 SPECT was high in the region with low score of QWMS. In conclusion, omnidirectional M-mode is useful for quantitatively determining the grade of cardiac ischemia by assessing the serial change of ventricular wall motion during dobutamine infusion.

Adrenergic beta-Agonists↗
PubMed1999

Effect of olprinone, a phosphodiesterase III inhibitor, on arterial wall distensibility: differentiation between aorta and common carotid artery.

Although the effects of phosphodiesterase III (PDE III) inhibitors as vasorelaxants have been well documented, there are only few data on the wall response of different arteries. We evaluated the artery-specific effect of olprinone (OP), one of the PDE III inhibitors, on the major branches of human arteries and peripheral circulation. In 14 healthy subjects (average age: 57.5 +/- 21.2 years), systolic and diastolic diameters (Ds and Dd, respectively) and the time velocity integral (VI) of flow velocity patterns were measured by M-mode and Doppler echocardiography in the carotid artery (CA), the ascending aorta (asAo), the abdominal aorta (abAo), and the left ventricular outflow tract. Blood pressure (BP) was simultaneously measured using a cuff sphygmomanometer. Measurements were taken before and 20min after a bolus injection of OP (0.2 microg/kg). Distensibility (Ds - Dd), stiffness parameter beta (In(systolic BP/diastolic BP)/(Ds/Dd - 1)), cardiac output (CO: (Flow Area) x VI x HR at left ventricular outflow), selective flow volume (FV: (Flow Area) x VI x HR at CA or abAo), and vascular resistance (VR: mean BP/(CO or FV)) were then calculated. The distensibility increased significantly after OP administration (P = 0.0015), but that of the asAo or abAo did not change. Although there was a significant increase in CO (P = 0.001) and a significant decrease in systemic VR (P = 0.001) following OP administration, the FV and VR of both CA and abAo did not change significantly. The selectiveness of the effect of OP was demonstrated in terms of the CA wall distensibility. This was thought to be attributable to the differences in the structural components or the reactivity of smooth muscle cells to OP.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1999

Relationship between myocardial tissue density measured by microgravimetry and sound speed measured by acoustic microscopy.

If myocardial tissue can be assumed to be fluid-like, myocardial tissue elasticity can be estimated by the sound speed of tissue based on the equation K = rho(c)2, where K is the elastic bulk modulus, rho is density, and c is the sound speed of tissue. However, little data exist regarding the relationship between the sound speed of tissue and tissue density. The purpose of the present study was to evaluate the relationship between the sound speed of tissue and tissue density of various diseased myocardia. Myocardial tissue specimens at autopsy were obtained from 10 control patients without cardiovascular disease, 8 patients with pressure overload left ventricular hypertrophy (POLVH), and 8 patients with cardiac amyloidosis (AMD). Myocardial tissue sound speed was measured using a scanning acoustic microscope operating in the frequency of 450 MHz, and tissue density was measured by microgravimetry. The sound speed in POLVH (1639 +/- 17 m/s) was higher and that in AMD (1565 +/- 11 m/s) was lower than that in control patients (1615 +/- 15 m/s) (p < 0.001) at the temperature of 20-22 degrees C. The density in POLVH (1.087 +/- 0.004 g/cm3) was higher and that in AMD (1.072 +/- 0.003 g/cm3) was lower than that in control patients (1.082 +/- 0.003 g/cm3) (p < 0.001). Tissue density correlated with sound speed in all three groups (r = 0.96, p < 0.001). Therefore, myocardial tissue sound speed data obtained by acoustic microscopy enabled us to evaluate tissue elasticity without measuring tissue density directly.

Acoustics↗
PubMed1999

Enhancement of ultrasound-accelerated thrombolysis by echo contrast agents: dependence on microbubble structure.

The combination of ultrasound (US) exposure and ultrasound contrast agent (UCA) further increases the amount of drug-mediated thrombolysis. The aim of this study was to examine the efficacy of the combination of US and UCA on tissue plasminogen activator (tPA) thrombolysis, and the dependence on the microbubble structure. A catheter-type transducer capable of US emission (10 MHz, spatial peak temporal average intensity = 1.02 W/cm2 and peak negative pressure = 0.33 MPa) in the continuous-wave mode was employed. In 28 artificial white thrombi, serial changes in acoustic properties monitored by echography and histopathology during the tPA-mediated thrombolysis were analyzed. The thrombi were assorted to 4 groups; UCA nontreated (Control), sonicated albumin (A)-, SH-U508A (SH)- and dodecafluoropentane emulsion (DDFP)-treated groups. Persistence of microbubble opacification and thrombus weight were also measured. After the sample was suspended in a beaker with tPA (8000U) and 100 mL of saline, the UCA was administered and the mixture exposed to US for 10 min. Weight reduction of the thrombus was greatest in the DDFP Group (-49 +/- 8%), and that in the A Group (-8 +/- 5%) was not significantly different from that in the Control Group (-5 +/- 1%). The persistence of the microbubbles expressed as the decay of the time-intensity curve, was longest in the DDFP Group. The echo intensity of the superficial layer of the thrombus exposed to US was high and weight loss was marked. Multiple cavity formation was observed histopathologically. The stability of the microbubbles was an important factor of the US and UCA enhancement effect on tPA-mediated thrombolysis. This combination therapy has potential for clinical application in patients with thrombotic arterial and venous occlusion and left arterial thrombus.

Adult↗
PubMed1999

Dependence of power Doppler image on a high pass filter instrumented in ultrasound machine.

The aim of this study was to examine the influence of flow velocity, beam incident angle and a wall motion filter on the intensity of power Doppler image of steady flow in vitro. Power Doppler images of flow were recorded using a 7.5-MHz linear transducer with the fixed repetition frequency, gain and frame rate settings at the velocity levels of 15, 20, 35 and 65 cm/s with the beam incident angles of 30 degrees and 60 degrees. The power (P) of received Doppler signal was digitized to 25 gray values (G) for imaging using a wall motion filter with the transfer function: G = a x log P + b (a, b = constant values). Image intensity was measured at the center of the flow image off-line and compared with the flow velocity measured by conventional pulsed wave Doppler. Below the Nyquist limit, G increased as velocity increased, and G with the incident angle 30 degrees was lower than those with 60 degrees. Overall relationship between the Doppler shift frequency and the image intensity exhibited an excellent correlation when fit to the theoretical curve derived from the filter property (r = 0.97). The signal intensity of power Doppler image of flow depends upon the mean Doppler frequency shift or the flow velocity and was clearly affected by the wall motion filter.

Echocardiography, Doppler↗
PubMed1999

The effect of combination therapy with interferon and cryofiltration on mesangial proliferative glomerulonephritis originating from mixed cryoglobulinemia in chronic hepatitis C virus infection.

Cryofiltration, which has developed from double filtration plasmapheresis (DFPP) with a cooling unit, is an on-line technique to remove cryoglobulin. We report on a patient who suffered from progressive edema and renal insufficiency caused by cryoglobulinemic membranoproliferative glomerulonephritis (MPGN), probably due to chronic hepatitis C virus (HCV) infection. To remove cryoglobulins and terminate the HCV infection, we utilized combination therapy with cryofiltration and interferon-alpha injection with corticosteroids. Interferon-alpha was capable of decreasing proteinuria but not diminishing cryoglobulin. Additional cryofiltration could remove cryoglobulin to an undetectable level. This combination therapy was partially successful to reduce proteinuria and prevent the progressive deterioration of renal function. The major adverse effects of this therapy were bleeding and myelosuppression. We conclude that this combination therapy may be effective and should be considered as treatment for cryoglobulinemic MPGN.

Aged↗