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Biomedical subjects

N Ohte

Publications and source records attributed to N Ohte.

At least 37 records · Page 2Linked to original sources
PubMed1997

The cardiac effects of pimobendan (but not amrinone) are preserved at rest and during exercise in conscious dogs with pacing-induced heart failure.

We compared the effects of pimobendan (0.25 mg/kg i.v.), a Ca++ sensitizer, with some phosphodiesterase-III inhibition effects, and amrinone (1 mg/kg plus 10 microg/kg/min i.v.), a PDE-III inhibitor, on left ventricular (LV) systolic and diastolic performance, both at rest and during exercise, in seven conscious dogs before and after pacing-induced congestive heart failure (CHF). Before CHF, under resting conditions, both pimobendan and amrinone caused a similar significant decrease in left ventricle size and end-systolic pressure, arterial elastance, and the time constant of LV relaxation. Similar results were obtained during exercise. Both agents also produced a similar increase in E(ES), the slope of the LV end-systolic pressure-volume relation (3.4 +/- 1.5 vs. 4.2 +/- 1.1 mm Hg/ml; amrinone vs. pimobendan). After CHF, the vasodilatory effects of amrinone and pimobendan were preserved both at rest and during exercise; however, the inotropic actions were different. After CHF, pimobendan increased E(ES) (3.9 +/- 0.5 vs. 5.7 +/- 0.4 mm Hg/ml, P < .05), decreased the time constant of LV relaxation, increased the maximum rate of LV filling (37 +/- 19 ml/sec) (P < .05) and produced a downward shift of the early diastolic portion of LV pressure-volume loop. Pimobendan also augmented LV contractile performance during CHF exercise. In contrast, after CHF, amrinone no longer produced a positive inotropic effect. Amrinone improved LV relaxation and filling, both at rest and during exercise after CHF, but significantly less than pimobendan. We conclude that after CHF, the cardiac response to a PDE-III inhibitor is attenuated, but the response to Ca++ sensitizer is preserved. Thus, after CHF, pimobendan is more effective than amrinone in enhancing LV contractile state, LV relaxation and LV filling both at rest and during exercise.

Amrinone↗
PubMed1996

Altered ventricular and myocyte response to angiotensin II in pacing-induced heart failure.

Alterations in the cardiac response to angiotensin II (Ang II) may contribute to the functional impairment in tachycardia-induced heart failure (congestive heart failure [CHF]). Accordingly, we studied the response to Ang II in eight conscious instrumented dogs before and after inducing CHF. Left ventricular (LV) performance was assessed by measuring LV pressure and LV volume. Isolated myocyte function was evaluated using computer-assessed videomicroscopy. In conscious animals before CHF, Ang II produced a load-dependent slowing of the time constant of LV relaxation (tau) and did not depress intact LV contractile function. After CHF, although Ang II produced a similar increase in LV systolic pressure, the increases in LV diastolic pressure and time constant tau were much greater, and contractile performance was depressed. These changes persisted when the elevation of end-systolic pressure was prevented by nitroprusside. Similar changes were also present after autonomic blockade. In isolated myocytes, before CHF, Ang II (10(-6) mol/L) produced a slight positive inotropic effect. In contrast, after CHF, Ang II produced a negative inotropic effect and slowed the rate of relengthening. The effects in the intact LV and myocytes were reversed by an Ang II AT1 receptor blocker (losartan). We conclude that pacing-induced CHF alters the LV and myocyte response to Ang II, so that Ang II produces direct depressions in intact LV contraction, relaxation, and filling and exacerbates myocyte contractile dysfunction. These effects are mediated through the activation of AT1 receptors.

Angiotensin II↗
PubMed1995

Coexisting type III hyperlipoproteinemia and familial hypercholesterolemia: a case report.

A 39-year-old man presented with type III hyperlipoproteinemia in association with heterozygous familial hypercholesterolemia (FH). He had extensive tuberous xanthomas over the knees and elbows and xanthomas in the Achilles tendons. He also had palmar xanthomas. He exhibited severe hypercholesterolemia and hypertriglyceridemia. This patient was heterozygous for FH, as evidenced by low low-density lipoprotein (LDL) receptor function on lymphocytes, and had type III hyperlipoproteinemia, as determined by apolipoprotein (apo) E phenotype 2/2 in isoelectric focusing of the E isoproteins and the presence of a broad beta band on electrophoresis. Because therapy consisting of diet restrictions and lipid-lowering agents such as clinofibrate and niceritrol did not decrease serum total cholesterol ([TC] 15.26 mmol/L) and triglyceride ([TG] 10.79 mmol/L) levels effectively, the patient underwent plasmapheresis once every 2 weeks using a dextran sulfate-cellulose column. Repeated plasmapheresis markedly reduced serum TC and TG and induced complete regression of the palmar xanthoma after 6 months. The severity of tuberous xanthomas on the knees and elbows was reduced after 2.5 years. After plasmapheresis, TC decreased to 1.94 mmol/L from 10.40 mmol/L and TG decreased to 0.33 mmol/L from 7.90 mmol/L. Plasmapheresis performed with a dextran sulfate-cellulose column was highly effective in removing the lipoprotein-remnant particles in this patient, leading to generalized improvement in the lipoprotein profile.

Adult↗
PubMed1995

Diastolic mitral annular motion in normal subjects and patients with coronary artery disease.

The purpose of this study was to evaluate the characteristics of mitral annular motion during diastole in 28 normal subjects, 40 patients with prior myocardial infarction (MI), and 23 patients with coronary artery disease but without prior MI. Mitral annular motion during diastole was obtained from the apex by M-mode echocardiography at the posterior wall of the left ventricle. Determinants of mitral annular excursion during early (MAE-E) and late diastole (MAE-L) were investigated in all subjects. Differences in the MAE-E, MAE-L, and the MAE-L:MAE-E ratio were compared among the three patient groups. The Doppler-derived transmitral flow velocity-time integral during early (EI) and late (AI) diastole and mitral annular excursions during diastole were obtained in 55 other patients with a prior MI and in 29 healthy volunteers. The relationships between the MAE-L:MAE-E ratio and AI:EI ratio in these two groups were studied. The MAE-E was determined mainly by heart rate and left ventricular ejection fraction (LVEF). The MAE-L was determined only by age. The magnitude of MAE-E was significantly less in patients with a prior MI than in normal subjects (P < 0.01). However, the MAE-L did not differ among the three groups. The MAE-L:MAE-E was higher in patients with a prior MI than in normal subjects (P < 0.05), and was significantly correlated with AI:EI in healthy volunteers (r = 0.65, P < 0.001) and in patients with a prior MI (r = 0.50, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Effects of volume loading on pulmonary venous flow pattern in dogs with normal left ventricular function.

The effects of altered loading conditions on the pattern of pulmonary venous flow are poorly understood. The authors investigated such effects, therefore, by using volume loading in 6 open-chest dogs. The pulmonary venous flow volume rate curve was obtained with a transit-time ultrasonic flowmeter at a fixed heart rate. Measurements were performed in the control and several states during the intravenous infusion of dextran. The influences of volume loading on hemodynamic and pulmonary venous flow variables were compared between the control state and three interventional states in which mean left atrial pressure was approximately 1, 2, and 3 mm Hg above the control value. The systolic flow volume (SI), which corresponds to left atrial reservoir volume, significantly increased, but the early diastolic flow volume (DI), which corresponds to left atrial conduit volume, did not show significant change with volume loading. The flow volume during left atrial contraction significantly increased with volume loading. The flow volume during one cardiac cycle (PVF) significantly increased with volume loading. Approximately 73% of increased PVF was distributed to the systolic flow. The rest was distributed to the early diastolic flow (14%) and to the flow during left atrial contraction (12%). The change in the ratio of SI/DI significantly and positively correlated with the change in mean left atrial pressure (r = 0.87, P < 0.001). These findings indicate that increased pulmonary venous flow induced by volume loading in dogs with normal left ventricular function is mainly distributed to the left atrial reservoir volume.

Animals↗
PubMed1995

Four-barrel aortic dissection involving the ascending aorta. A case report.

A fifty-four-year-old woman was evaluated at the authors' hospital for symptoms of repeated chest and back pain. The symptoms had recurred for five months prior to admission. A dynamic computed tomographic scan was performed on admission and demonstrated an enlarged ascending aorta with four barrels secondary to split intimal flaps. This case is an extremely rare example of a patient with a four-barrel aortic dissection involving the ascending aorta.

Aortic Dissection↗
PubMed1995

Clinical significance of reverse redistribution on 24-hour delayed imaging of exercise thallium-201 myocardial SPECT: comparison with myocardial fluorine-18-FDG-PET imaging and left ventricular wall motion.

UNLABELLED: Clinical significance of reverse redistribution on 24-hr delayed images after exercise 201Tl myocardial SPECT was investigated in 16 patients with recent myocardial infarction. METHODS: Findings of 24-hr delayed 201Tl SPECT imaging were compared with those of glucose-loaded 18F-fluorodeoxyglucose (FDG) imaging by myocardial PET and with left ventricular wall motion obtained by bi-plane contrast left ventriculography. In each patient, transaxial thallium images and corresponding 18F-FDG images were divided into five ROIs. RESULTS: Reverse redistribution was found in 15 of 80 regions. The mean FDG activity score in regions with reverse redistribution was significantly lower than that in regions having normal or slightly decreased thallium activity on 24-hr delayed imaging; it was significantly higher than that in regions having severely decreased or no thallium activity on 24-hr delayed imaging. The mean wall motion score in regions with reverse redistribution was significantly lower than in regions with normal or slightly decreased thallium activity, however, it was significantly higher than that in regions with moderately or more decreased thallium activity. CONCLUSION: These findings demonstrate that in regions showing reverse redistribution on 24-hr delayed 201Tl imaging, myocardial exogenous glucose utilization and left ventricular wall motion had deteriorated, but were not on a level with the scar.

Aged↗
PubMed1994

Percutaneous transluminal coronary angioplasty of "superdominant" left anterior descending artery. A case report.

A seventy-one-year-old woman suffering from angina pectoris had a superdominant left anterior descending artery with a 95% stenosis just after it extended the apex. This superdominant artery was demonstrated angiographically by the findings that it ran in the posterior interventricular sulcus and reached the crux of the heart. Percutaneous transluminal coronary angioplasty for the stenosis beyond the apex was successfully performed. After the procedure, she was relieved from chest pain.

Aged↗
PubMed1993

Detection of coronary artery stenosis by dipyridamole radionuclide ventriculography.

We assessed the usefulness of dipyridamole radionuclide ventriculography for detecting significant coronary artery stenosis in 89 patients who were undergoing cardiac catheterization. Radionuclide ventriculography was performed before and after the infusion of dipyridamole (0.56 mg/kg). The end-diastolic regions of interest of the left ventricle were divided into 5 sectors for calculation of the regional ejection fractions. Results were considered to be positive when the regional ejection fraction decreased by more than 5% after the infusion of dipyridamole. The presence of significant coronary artery stenosis (> 75%) was demonstrated by arteriography in 49 patients and was absent in 40 patients. A decrease in the regional ejection fraction greater than 5% was observed in 41 (84%) of the 49 patients with significant coronary artery stenosis and in 2 of the 40 without significant coronary stenosis. The sensitivity and specificity of this method for detecting significant coronary artery stenosis were 84% and 95%, respectively. We conclude that a decrease in the radionuclide-determined regional ejection fraction after the infusion of dipyridamole reflects left ventricular dysfunction and is a sensitive and specific indicator of significant coronary artery stenosis.

Adult↗
PubMed1992

Noninvasive evaluation of left ventricular performance by the shortest distance between mitral leaflets coaptation and interventricular septum at end-systole.

We attempted to evaluate left ventricular performance from the shortest distance between the mitral leaflets coaptation and the interventricular septum at end-systole (MVC-IVS distance). The subjects were 37 patients with coronary artery disease (CAD) with prior myocardial infarction (MI), 8 with CAD without prior MI, 22 with atypical chest pain, and 4 with aortic regurgitation. The MVC-IVS distance was measured on a two-dimensional echocardiogram obtained from the parasternal or apical long-axis view and frozen at end-systole. Left ventricular end-systolic volume and end-diastolic volume were obtained by left ventriculography, and the left ventricular ejection fraction was calculated. A significant positive correlation was observed between the MVC-IVS distance and the end-systolic volume (r = 0.83, p less than 0.001); a close correlation was observed between the MVC-IVS distance end-systolic volume and ejection fraction by monoexponential fitting (r = -0.91, p less than 0.001). Thus, a significant negative correlation was observed between the MVC-IVS distance and the left ventricular ejection fraction (LVEF) (r = -0.83, p less than 0.001). An MVC-IVS distance of greater than or equal to 30 mm suggests diagnosis of left ventricular dysfunction (LVEF less than 50%) with high sensitivity (94.4%) and specificity (90.6%), while a value less than 30 mm suggests that the left ventricular performance is likely to be normal. Thus one can easily evaluate the left ventricular performance noninvasively using this new index.

Adult↗
PubMed1992

Evaluation of a new systolic time interval, the Q-V peak: effects of heart rate, contractile state, and loading conditions in dogs.

The authors investigated the effects of alterations in heart rate, contractility, and loading conditions on a newly defined systolic time interval, the Q-V peak, in 46 anesthetized dogs. The Q-V peak was measured as the time from the beginning of the electrocardiographic Q wave to the moment at which the blood flow rate reached its peak in the ascending aorta as determined with an electromagnetic flowmeter. The Q-V peak did not change significantly as the heart rate was varied by atrial pacing between 70 and 110 beats/minute. The Q-V peak shortened when the contractility was augmented with dobutamine (p = 0.0001) and was prolonged when it was depressed with propranolol (p = 0.0001). However, the Q-V peak did not change significantly when the left ventricular end-diastolic pressure or the mean aortic blood pressure was increased to 130% or decreased to 70% of the baseline values. These findings suggest that one may also evaluate left ventricular performance by measuring the time to systole, which the authors define as the Q-V peak.

Animals↗
PubMed1992

[Differentiation between "pseudonormal" from normal transmitral flow velocity waveforms by evaluating isovolumic relaxation time].

We tried to differentiate "pseudonormal" from normal transmitral flow velocity waveforms by evaluating isovolumic relaxation times (IRT) in patients with old myocardial infarction. Forty-three healthy volunteers and 54 patients with old myocardial infarction were studied. Transmitral flow velocity waveforms were obtained by pulsed Doppler echocardiography with a phonocardiogram. Early peak filling velocity (E) and late peak filling velocity (A) were measured, and the E/A ratio was calculated. The time from the beginning of the IIA sound to the onset of transmitral flow was defined as IRT. We observed a significantly positive correlation between IRT and age in the healthy volunteers (r = 0.56, p < 0.01). Based on these results, we selected age-matched healthy subjects (control group, n = 23) older than 35 years from the healthy volunteers. We divided the patients into 2 groups; those with a mean pulmonary capillary wedge pressure (mPCWP) of > or = 16 mmHg (H group, n = 9) and those with an mPCWP of < 16 mmHg (L group, n = 45). E, E/A, IRT, mean blood pressure (mBP), and heart rate were compared among the H, L, and control groups. There was no significant difference in mBP or heart rate between these 3 groups. Both E and E/A were significantly lower in the L group than in the control group (p < 0.05), however, no significant difference was observed in E and E/A between the H and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Severity of coronary atherosclerosis correlates with the respiratory component of heart rate variability.

Decreased vagal activity is frequently observed in coronary artery disease, but the mechanism of this association is unknown. We investigated cardiac autonomic function by relating heart rate spectral components to clinical and angiographic findings in 80 patients who were undergoing coronary angiography. The age- and sex-adjusted magnitude of the respiratory spectral component, which is an index of cardiac vagal tone, showed a significant negative correlation with the extent of coronary atheromatosis (r = -0.43, p less than 0.0001) and a less significant negative correlation with the severity of coronary stenosis (r = -0.30, p = 0.0070). These relationships were independent of previous myocardial infarction and of left ventricular function. Stepwise regression analysis showed that the respiratory spectral component contributed to atheromatosis independently of established coronary risk factors (partial R2 = 9.4%, p = 0.002), but not to stenosis. Our results support the hypothesis that decreased cardiac vagal activity is associated with an increased risk of coronary atherosclerosis.

Adult↗
PubMed1991

Continuous-wave Doppler echocardiography for evaluating left ventricular performance--clinical significance of a new systolic time interval.

Left ventricular performance was evaluated in 51 patients with acute myocardial infarction and angina pectoris using parameters derived from the flow velocity waveform at the ascending aorta. Flow velocity waveforms were obtained from the suprasternal notch by continuous-wave Doppler echocardiography and were recorded on a line-scan recorder at a paper speed of 100 mm/sec with lead II ECG. The peak flow velocity and the systolic time interval from the beginning of ECG Q wave to the peak flow velocity (Q-V peak interval) were measured. Relationships were investigated between these parameters and the left ventricular ejection fraction (LVEF) obtained from multigated equilibrium blood pool imaging with 99mTc-pertechnetate. The peak flow velocity did not correlate with LVEF (r = 0.27). However, a highly significant negative correlation was observed between the systolic time interval Q-V peak and LVEF (r = -0.84, p less than 0.001). The regression equation was LVEF = -0.46 X (Q-V peak) + 142. We conclude that left ventricular performance can be evaluated in patients with coronary artery disease at the bedside using the Q-V peak interval measured from simultaneous recording of the velocity waveform at the ascending aorta and the ECG.

Adult↗
PubMed1991

[Determinants of mitral inflow velocity profiles in relation to left ventricular volume change: evaluations by pulsed Doppler echocardiography and left ventriculography].

We evaluated relationships between pulsed Doppler echocardiographic (PDE) parameters of flow velocity profiles across the mitral orifice and left ventriculographic (LVG) parameters of left ventricular volume changes. Subjects consisted of 19 patients with coronary artery disease and 12 patients with chest pain syndrome. Peak flow velocities at the rapid filling (E) and atrial contraction (A) were measured by PDE. Time constant of left ventricular relaxation (T), left ventricular minimum pressure (LVPmin), LV end-diastolic pressure (LVEDP) and pulmonary capillary wedge V wave pressure (PCW-V) were measured during cardiac catheterization. From the analysis of LVG, the rapid filling fraction (RFF), and the atrial filling fraction (AFF) were obtained. The left ventricular chamber stiffness (K) was identified by the analysis of the pressure-volume relationship of the left ventricle. We investigated the relationship between A/E and AFF/RFF by univariate linear regression analysis. We then performed stepwise multivariate linear regression analysis to predict E, A, A/E, RFF, AFF and AFF/RFF by the variables of left ventricular filling, i.e., T, LVPmin, LVEDP, PCW-V, K, heart rate (at the examination of PDE or LVG), mean arterial blood pressure (at PDE or LVG) and age. The A/E correlated significantly with AFF/RFF (r = 0.50, p < 0.01). The results of the multivariate linear regression analyses were as follows: [sequence: see text] The correlation of A/E and AFF/RFF were explained by some variables, except the variable T. The results of uni- and multivariate linear regression analyses showed that factors affecting the flow velocity profile across the mitral orifice did not account for the left ventricular volume changes. We also observed that, even in subjects with coronary heart disease, aging is a main factor that influences peak flow velocity at atrial contraction (A).

Adult↗
PubMed1990

Decreased magnitude of heart rate spectral components in coronary artery disease. Its relation to angiographic severity.

We analyzed the spectral components of RR interval variability under controlled respiration (15 breaths/min) in 56 patients (age range, 35-73 years) referred for coronary angiography; 14 patients had multivessel disease (group M), 21 had one-vessel disease (group S), and 21 had nonsignificant disease or normal coronary artery (group N). There were 43 healthy controls (age range, 36-71 years) (group C). The patients had no clinical evidence of heart failure, hypertension, diabetes mellitus, or acute stage of infarction and had taken no medication for 3 days. The autoregressive power spectral density of RR interval variability contains two major components, respiratory sinus arrhythmia (RSA) (0.25 Hz) and Mayer wave-like sinus arrhythmia (MWSA) (0.04-0.15 Hz), which have magnitudes that are quantitative markers of cardiac vagal activity and sympathetic activity with vagal modulation, respectively. We represented the magnitudes by the coefficient of component variance (CCV), which provided the amplitude relative to the mean RR interval. The age- and sex-adjusted mean of CCVRSA significantly decreased with advancing angiographic severity (1.64 +/- 0.09%, 1.66 +/- 0.12%, 1.22 +/- 0.13%, and 0.81 +/- 0.16% for groups C, N, S, and M, respectively) (p = 0.0001). The CCVRSA was unrelated to left ventricular function, previous myocardial infarction, or stenosis of any specific artery including the sinoatrial and atrioventricular node arteries. The CCVMWSA decreased only in group M (p = 0.0462). These results indicate that coronary artery disease is associated with vagal dominant impairment in autonomic cardiac function and that reduction in the vagal cardiac function correlates with the angiographic severity.

Adult↗