Biomedical subjects

Tomotsugu Tabata

Publications and source records attributed to Tomotsugu Tabata.

25 records · Page 2Linked to original sources

PubMed2002

The role of short- and long-axis function in determining late diastolic left ventricular filling in patients with hypertension: assessment by pulsed Doppler tissue imaging.

Left ventricular (LV) wall motion velocity during atrial systole is mediated by both transmitral flow and LV myocardial compliance at end-diastole. LV wall distensibility along the long- and short-axis during atrial systole and late diastolic LV filling may vary according to the remodeling of LV morphology. We measured LV wall motion velocities along the long and short axes using pulsed Doppler tissue imaging in 127 patients with hypertension to evaluate the relationship between the hemodynamic changes and LV morphology and to determine the role of both long- and short-axis function in late diastolic LV filling. Participants were classified into 3 groups according to LV dimension and end-diastolic wall thickness determined by M-mode echocardiography: group A (n = 62) without LV dilation or hypertrophy, group B (n = 55) with LV hypertrophy, and group C (n = 10) with LV dilation and systolic dysfunction. The time constant of the LV pressure decay during isovolumic diastole and the LV end-diastolic pressure were longest and greatest, respectively, in group C, compared with groups B and A. There were no significant differences in active left atrial emptying volume during atrial contraction determined by computerized echocardiographic 3-dimensional reconstruction among patient and control groups. The peak atrial systolic motion velocity of the LV posterior wall along the long axis was significantly lower in groups B and C, particularly in the latter group, than in group A. The peak atrial systolic motion velocity of the LV posterior wall along the short axis was greatest in group B and was lowest in group C compared with the other groups, respectively. The peak atrial systolic motion velocity of the LV posterior wall was greater along the long axis than the short axis in group A, but was less than the short axis in group B. In conclusion, the long- and short-axis function of the LV wall during atrial systole varies in patients with hypertension according to the severity of hemodynamic and morphologic abnormalities. The degree of LV wall expansion along the short axis is an important factor resulting from the atrial kick, and a determinant of its effectiveness.

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PubMed2002

Induction and maintenance of an experimental model of severe cardiomyopathy with a novel protocol of rapid ventricular pacing.

OBJECTIVE: An animal model of chronic severe heart failure is needed to evaluate new mechanical devices, surgical procedures, and medical therapies. The purpose of this study was to evaluate a unique new model of severe heart failure developed by means of a novel protocol of rapid ventricular pacing. METHODS: Heart failure was induced in 8 mongrel dogs by means of rapid ventricular pacing (230 beats/min) for 4 weeks. After a sham operation, maintenance pacing at a reduced rate (190 beats/min) was continued for another 4 weeks. RESULTS: Left ventricular systolic function was significantly reduced at week 4 and remained low at week 8, including the slope of the end-systolic pressure-volume relationship (2.4 +/- 1.0 vs 0.7 +/- 0.2 vs 0.8 +/- 0.3 mm Hg/mL [baseline vs week 4 vs week 8, respectively]), ejection fraction (63% +/- 5% vs 28% +/- 7% vs 33% +/- 5%), and cardiac output (3.1 +/- 0.7 vs 2.0 +/- 0.3 vs 2.2 +/- 0.7 L/min). Significant ventricular remodeling changes took place with increased ventricular volumes and circumferential wall stress, which were stable between weeks 4 and 8. Serum catecholamine and atrial natriuretic polypeptide levels also increased from baseline but stabilized between weeks 4 and 8. The end-diastolic pressure-volume relationship also showed stable diastolic function between weeks 4 and 8. CONCLUSIONS: Induction pacing at 230 beats/min readily created severe heart failure in all animals, and a new technique of maintenance pacing provided a consistent model of severe heart failure. This model can be used to study a variety of new interventions for heart failure.

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PubMed1999

Assessment of the Systolic Left Ventricular Myocardial Velocity Profile and Gradient Using Tissue Doppler Imaging in Patients with Hypertrophic Cardiomyopathy.

To determine the systolic characteristics of the hypertrophied myocardium in patients with hypertrophic cardiomyopathy (HCM), we evaluated the left ventricular [left ventricle (LV)] myocardial velocity profile (MVP) and gradient obtained from tissue Doppler imaging (TDI). Transmural wall-motion velocities in the ventricular septum and LV posterior wall were recorded in 12 patients with asymmetric septal hypertrophy and 12 healthy volunteers, and their profiles and gradients were determined. The maximum systolic myocardial velocity gradient in the ventricular septum was significantly lower in the HCM group than in the control group (0.88 +/- 0.35 versus 2.24 +/- 0.41; P < 0.001), whereas the gradient in the LV posterior wall was only slightly lower in the HCM group than in the control group (2.69 +/- 0.82 versus 3.45 +/- 0.96). In the control group, the MVPs in the ventricular septum and LV posterior wall were closely linear, suggesting that the transmural velocity is uniform during systole. MVPs in the ventricular septum and LV posterior wall in the HCM group also were closely linear, whereas the distribution of velocities in the ventricular septum was fairly dispersed compared with the control group. The myocardial velocity gradient on the right ventricular side of the ventricular septum decreased or disappeared in the patients with HCM, suggesting a nonuniform distribution of velocities. In conclusion, the MVP and gradient obtained from TDI may represent new indices for evaluating regional LV contractile abnormality in patients with HCM.

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PubMed1998

Left Atrial Contribution to Left Ventricular Filling in Patients with Mitral Stenosis: Combined Analysis of Transmitral and Pulmonary Venous Flow Velocities.

We recorded transmitral and pulmonary venous flow velocities using transthoracic continuous-wave and transesophageal pulsed Doppler echocardiography, respectively, in 36 patients with mitral stenosis who were in sinus rhythm to investigate the left atrial contribution to left ventricular filling in mitral stenosis. The mitral valve area was determined by transthoracic two-dimensional short-axis echocardiography. Patients were classified as having mild stenosis (>/=1.5 cm(2), n = 17) or moderate stenosis (<1.5 cm(2), n = 19). The mean pulmonary capillary wedge pressure and left atrial maximal diameter were significantly larger, and left atrial volume change during atrial contraction was significantly smaller in the moderate group than in the mild group. The percent left atrial contribution to left ventricular filling, estimated from the transmitral flow velocity, the peak atrial systolic velocity, and the percent ratio of left atrial systolic regurgitation to left atrial filling, estimated from the pulmonary venous flow velocity, were significantly lower in the moderate group than in the mild group. The percent left atrial contribution to left ventricular filling, the peak atrial systolic velocity, and the percent ratio of left atrial systolic regurgitation to left atrial filling were positively correlated with the mitral valve area and negatively correlated with the mean pulmonary capillary wedge pressure. These results suggest that the left atrial contribution to left ventricular filling in patients with mitral stenosis in sinus rhythm decreases as the severity of valve stenosis increases, and that analysis of the atrial systolic waves of the transmitral and pulmonary venous flow velocities provides important information for evaluation of left atrial systolic performance in patients with mitral stenosis.

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PubMed1998

Transesophageal Pulsed Doppler Echocardiographic Study of Systolic Flow Velocity Patterns of the Pulmonary Vein in Patients with Atrial Fibrillation.

We recorded pulmonary venous flow velocity in 27 patients with atrial fibrillation using transesophageal pulsed Doppler echocardiography to investigate the cycle length-dependent characteristics and background of early systolic reversal and second systolic forward waves. The study group consisted of 15 patients with mitral stenosis, 5 patients with left atrial myxoma, and 7 patients without underlying organic heart disease; they were compared with 20 normal controls in sinus rhythm. The mean pulmonary capillary wedge pressure was significantly greater in patients with mitral stenosis and left atrial myxoma than in normal controls and in patients with isolated atrial fibrillation. The mean peak velocity of the early systolic reversal wave was also significantly greater in patients with mitral stenosis and left atrial myxoma than in patients with isolated atrial fibrillation. The mean peak velocity of the second systolic forward wave was significantly lower in patients with mitral stenosis and left atrial myxoma than in controls and in patients with isolated atrial fibrillation. The preceding RR interval had significant negative correlations with the peak early systolic reversal velocity, left atrial pressure during closure of the mitral valve, and peak V wave height of the pulmonary capillary wedge pressure in patients with mitral stenosis and left atrial myxoma. In the same patient groups, the preceding RR interval had significant positive correlations with the peak second systolic forward velocity and amplitudes of the mitral annular and interatrial septal motions during ventricular systole. The variations in the peak velocities of the early systolic reversal and second systolic forward waves with the preceding RR interval were smaller in patients with more severe mitral stenosis. In conclusion, early systolic reversal waves of the pulmonary venous flow velocity reflect left atrial pressure, and the second systolic forward waves reflect left atrial filling. Both velocities vary with disease conditions or preceding RR intervals in atrial fibrillation.

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PubMed1997

Left Atrial Systolic Performance in the Presence of Elevated Left Ventricular End-Diastolic Pressure: Evaluation by Transesophageal Pulsed Doppler Echocardiography of Left Ventricular Inflow and Pulmonary Venous Flow Velocities.

We recorded left ventricular inflow (LVIF) and pulmonary venous flow (PVF) velocities by transesophageal pulsed Doppler echocardiography in 25 patients with a ratio of peak atrial systolic to early diastolic LVIF velocity of <1 and a left ventricular end-diastolic pressure (LVEDP) of 15 mmHg or greater, as well as in 30 normal subjects. The group consisted of 14 patients with prior myocardial infarction, 7 with dilated cardiomyopathy, and 4 with cardiac amyloidosis, and were divided into: (1) group A (n = 7): peak atrial systolic LVIF velocity of 40 cm/sec or greater; (2) group B (n = 7): peak atrial systolic LVIF velocity of <40 cm/sec and peak atrial systolic PVF velocity of 30 cm/sec or greater; and (3) group C (n = 11): peak atrial systolic LVIF velocity of <40 cm/sec and peak atrial systolic PVF velocity of <30 cm/sec. Although LVEDPs in groups B and C were significantly greater than in group A, there was no difference between groups B and C. The mean pulmonary capillary wedge pressure (mPCWP) in group C was significantly greater than in groups A and B, but there was no difference between groups A and B. The difference between LVEDP and mPCWP (LVEDP - mPCWP) in group B was significantly higher than in groups A and C. Dilatation of the left atrium (LA) was seen in all three groups, particularly in groups B and C. There were no differences in peak atrial systolic LVIF velocity and LA volume change during atrial contraction between group A and the control group, and there were no differences in LA volume change and peak second systolic PVF velocity between groups A and B. LA volume change and peak second systolic PVF velocity were significantly less in group C than in groups A and B. Among the four patients whose courses could be observed after medical treatment with diuretic and vasodilator, one changed from group B to A, one from group B to C, one from group C to A, and one remained in group C. Thus, recording of peak atrial systolic LVIF and PVF by transesophageal pulsed Doppler echocardiography permits detailed evaluation of LA systolic performance in the presence of elevated LVEDP. These two variables provide important information for less invasive differentiation of LA afterload mismatch from LA myocardial failure.

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PubMed1996

A Case of Cardiac Amyloidosis Presenting with Mid- to Late Diastolic Retrograde Flow from the Left Atrium to the Pulmonary Vein: Transesophageal Pulsed Doppler Echocardiographic Observations.

A patient of cardiac amyloidosis was found to have mid- to late diastolic retrograde flow from the left atrium (LA) to the pulmonary vein. Congo-red staining was positive for amyloid in the rectal tissue. M-mode and two-dimensional echocardiograms revealed symmetric hypertrophy and typical speckled pattern of the left ventricle (LV). The LV pressure curve showed a dip and plateau configuration during diastole, and end-diastolic pressure was 28 mmHg. In addition, the LV pressure was high at mid-diastole, surpassing the pulmonary capillary wedge pressure from mid- to late diastole. The transmitral flow velocity revealed "restrictive" pattern, and the pulmonary venous flow velocity showed retrograde flow from the LA to the pulmonary vein during mid-diastole and atrial systole. It is suggested that recording of the pulmonary venous flow velocity by transesophageal pulsed Doppler echocardiography is useful for understanding the mechanism of the development of pulmonary congestion or edema. (ECHOCARDIOGRAPHY, Volume 13, November 1996)

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