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K Dohi

Publications and source records attributed to K Dohi.

At least 163 records · Page 9Linked to original sources

Contribution of long axis motion of left ventricular outflow to calculation of left ventricular stroke volume.

Stroke volume can be calculated by using noninvasive Doppler techniques. The products of pulsed Doppler stroke distance of left ventricular outflow and left ventricular outflow area can often be used to calculate stroke volume. However, left ventricular outflow also moves longitudinally toward the apex of the ventricle during systole, so that zero velocity flow cannot be detected by the usual pulsed Doppler studies. We evaluated the contribution of these zero velocity flow to the noninvasive estimation of left ventricular stroke volume in 20 patients with left ventricular disease and in 20 age matched healthy controls. Left ventricular stroke distance was calculated by summing the Doppler stroke distance and the outflow long axis motion. The percentage of zero velocity flow for total stroke volume was calculated in each group. Cardiac output was also measured by thermo-dilution technique. The percentage of zero velocity flow for total noninvasive stroke volume in patients with left ventricular disease was 2.5 +/- 1.1 ml (4.0 +/- 1.5%), significantly lower than in normal subjects, 3.6 +/- 1.0 ml (5.5 +/- 1.5%) (p < 0.05). These long axis motions are significantly reduced, especially in left ventricular disease. Amplitudes of the left ventricular outflow long axis motion were correlated with Doppler stroke distance in all (r = 0.54, p < 0.01). In patients with myocardial infarction, stroke volume by thermo-dilution methods and calculated stroke volume showed good correlation both only by Doppler stroke distance (y = 1.044x + 0.547, r = 0.968) and by Doppler and long axis motion (y = 0.989x + 0.521, r = 0.974). Compared with stroke volume measured by thermodilution method, stroke volume calculated only by Doppler stroke distance was underestimated. We thus demonstrated the influence of zero velocity flow on left ventricular outflow both in patients with left ventricular disease and in normal subjects.

Adult↗

Estimation of the right ventricular volume and ejection fraction by transthoracic three-dimensional echocardiography. A validation study using magnetic resonance imaging.

AIMS: To validate the use of three-dimensional transthoracic echocardiography compared with the magnetic resonance imaging for determination of right ventricular volume and ejection fraction. METHODS AND RESULTS: We recorded transthoracic echocardiographic images starting from the apical four-chamber view in which the RV is clearly visualized in 15 healthy volunteers. The scanning plane of the RV was obtained by the rotational scanning technique in 2 degree angular increments for three-dimensional reconstruction. The RV volumes in end-diastole and end-systole were calculated using a Tomtec three-dimensional reconstruction computer. We also assessed the RV by cine magnetic resonance imaging using the Siemens Magnetom Impact Expert (1.0 T). Cine gradient echo images were obtained in the short axis of the RV. The RV volume at each phase was calculated by Simpson's method. We also calculated the RV ejection fraction. The RV volumes in end-diastole and end-systole were 111 +/- 22 ml and 52 +/- 13 ml, respectively as determined by three-dimensional echo, and 115 +/- 18 ml and 55 +/- 14 ml determined by MRI. The right ventricular volumes at end-diastole and end-systole determined by three-dimensional echo were correlated with the volumes determined by MRI (r = 0.94 and 0.97, respectively, p < 0.001). The RV ejection fraction determined by three dimensional echo was also correlated with the ejection fraction determined by MRI (r = 0.90, p < 0.01). CONCLUSIONS: Three-dimensional transthoracic echocardiography provided reliable calculations of the right ventricular volume and ejection fraction.

Adult↗

Assessment of the normal adult right ventricular diastolic function using M-mode echocardiographic measurement of tricuspid ring motion.

Right ventricular function can be evaluated echocardiographically by assessing the longitudinal motion of the tricuspid ring recorded in the apical four chamber view. In this study, we applied this technique to assess the right ventricular diastolic function in 10 healthy Japanese men (mean age: 28 +/- 6 years; age range: 20-43 years). Echocardiographic studies were performed with a phased-array imaging system using a 2.5 MHz probe. Tricuspid ring motion was measured by two-dimensional echo guided M-mode echocardiogram of the right lateral tricuspid ring. The excursion of the tricuspid ring during early diastole (DS; mm) and the peak rate of change of the excursion (dS/dt; mm/sec) were measured. We also assessed the right ventricular function by cine magnetic resonance imaging (MRI). Cine gradient echo images were obtained along the short axis of the right ventricle. The right ventricular volume at each phase of the cardiac cycle was calculated by Simpson's method and time-volume curves were constructed. The peak filling rate (dV/dt; ml/s) was determined from these time-volume curves. The dS was 12.8 +/- 2.5 mm, dS/dt was 132 +/- 27 mm/sec and dV/dt was 269 +/- 66 ml/s. There were significant positive correlations between dS and dV/dt (r = 0.80, P < 0.01), and between dS/dt and dV/dt (r = 0.45, P < 0.05). Based on our results, M-mode echocardiographic measurements of tricuspid ring motion may be used to assess the right ventricular diastolic function.

Adult↗

The outcome of liver transplantation at various times (70, 120, and 134 days) after the initiation of carcinogenesis in rats.

The therapeutic results of liver transplantation for primary liver cancer have not been satisfactory. The high rate of recurrence appears to be due to the inadequate care taken in selecting the most appropriate candidates for orthotopic liver transplantation (OLT), the presence of circulating hepatocellular carcinoma (HCC) cells and micrometastases at the time of liver transplantation, and the tumor growth-promoting effects of immunosuppressive agents. We believe that HCC patients must be carefully staged in order to identify those most suitable for OLT. We therefore induced HCC in pure-strain rats by the oral administration of diethylnitrosamine (DEN) and studied the outcomes of liver transplantation at various time points (70, 120, and 134 days) after the initiation of carcinogenesis. The mean survival time (MST +/- SD) of the non-OLT control group (N = 14) was 18.2 +/- 5 days after Day 120. The survival time of the four rats in the OLT Day 120 group was 81.3 +/- 20.6 days after transplantation. One rat showing full weight recovery soon after transplantation survived for 97 days after transplantation and then succumbed to recurrence. The survival time of the four rats in the OLT Day 134 group was 7.3 +/- 5.0 days after transplantation. The survival time of the three rats in the OLT Day 70 group was 145.3 +/- 70.0 days after transplantation, with a maximum survival of 221 days until death. Significantly prolonged survival, as compared with that in the non-OLT group, was observed in the OLT Day 70 and OLT Day 120 groups (p < 0.01), while there was no significant prolongation in the OLT Day 134 group (NS). The timing of liver transplantation is a very important factor. Preoperative assessment of factors potentially affecting recurrence in HCC patients is imperative for selecting the most appropriate candidates for OLT. Careful selection of candidates for OLT should always be considered the key to successful liver transplantation (i.e., long-term survival) for patients with liver cancer.

Animals↗