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Biomedical subjects

R Omoto

Publications and source records attributed to R Omoto.

At least 127 records · Page 7Linked to original sources
PubMed1989

Assessment of Doppler color flow mapping in quantification of aortic regurgitation--correlations and influencing factors.

Real-time two-dimensional Doppler echocardiography (Doppler color flow mapping) offers useful information on valvular regurgitation. In order to quantify aortic regurgitation by Doppler color flow mapping, this study determined the relationships between regurgitant jet dimensions and angiographic grades in 100 patients, and between regurgitant jet dimensions and regurgitant fractions or regurgitant volumes in 47. Doppler data were obtained using 4 different echo windows, parasternal long and short axes, and apical two- and four-chamber views. Maximum jet area, length and diameter taken from all available views were examined in relation to angiographic grades, regurgitant fractions and regurgitant volumes. Moreover, we analyzed the technical, biological and hemodynamic factors influencing these relationships. Significant correlations were found between all maximum jet dimensions and angiographic grade (diameter, r = 0.641; length, r = 0.549; area, r = 0.611; p less than 0.01). Means and standard deviations for maximum jet dimensions according to angiographic grading revealed significant differences between all grades except in jet length between grades 3 and 4. However, these relations tended to be influenced by various factors: equipment, echo window, shape of jet, coexistence with mitral stenosis or aortic stenosis, left ventricular size, left ventricular stroke volume, and diastolic blood pressure. On the other hand, with regurgitant fractions and regurgitant volumes, maximum jet dimensions correlated well (diameter, r = 0.614 and 0.567; length, r = 0.769 and 0.767; area, r = 0.791 and 0.773; p less than 0.01) when data associated with atrial fibrillation were excluded. Thus significant correlations between regurgitant jet dimensions in Doppler color flow mapping and angiographic grades can be obtained in all patients despite various factors influencing jet dimensions. Better correlations with regurgitant fractions or regurgitant volumes may be expected in patients with normal sinus rhythm.

Adult↗
PubMed1989

[Responses of aortocoronary bypass graft flow to nitroglycerin, nifedipine and exercise test: a two-dimensional color Doppler echocardiographic study].

To assess the effects of coronary vasodilators and exercise on the blood flow dynamics of aortocoronary bypass grafts (ACBG), two-dimensional Doppler echocardiography was performed in 43 consecutive patients with ACBG of the left coronary artery. Doppler velocity signals of 14 internal mammary artery grafts (IMAG) and three saphenous vein grafts (SVG) were imaged in 15 patients using 5MHZ and 7.5MHZ convex-linear Doppler flow probes. Cross-sectional blood flow velocities and graft internal dimensions were continuously measured before and after the sublingual administration of nitroglycerin (0.3 mg) and nifedipine (20 mg), during isometric handgrip and bicycle ergometer exercise tests. 1. Regurgitant flow in isometric contraction time to early systole was observed in 14 of the 15 patients. Pulsatile diastolic blood flow with mean velocity of 14 +/- 6 cm/sec and volume of 49 +/- 25 ml/min was significantly higher than those in systole (7 +/- 7 cm/sec and 8 +/- 7 ml/min) as observed in IMAG and SVG. IMAG showed smaller vessel dimensions, higher flow velocities and lower flow volumes compared with those of SVG. 2. Nitroglycerin and nifedipine increased blood flow volumes (75 +/- 12%, 79 +/- 11%) and velocities (29 +/- 8%, 28 +/- 8%) due to dilatation of graft vessels (18 +/- 3%, 19 +/- 3%). Nifedipine, in contrast to nitroglycerin, induced sustained increases in graft flows. 3. Isometric handgrip and ergometer bicycle exercise tests increased blood flow volumes (34 +/- 9%, 61 +/- 14%) and velocities (31 +/- 11%, 42 +/- 12%) with elevation of double products (22 +/- 14%, 37 +/- 26%). Ergometer bicycle exercise induced similar responses in systole and diastole, whereas isometric handgrip test induced higher ratios of graft flow volume in systole (67 +/- 25%) compared to those in diastole (28 +/- 9%). In conclusion, two-dimensional color Doppler echocardiography is a promising means for the quantitative analysis of blood flow dynamics, assessments of the variable effects of coronary vasodilators and the physiological responses to exercise tests for the aortocoronary bypass graft flow in the early postoperative state.

Aged↗
PubMed1989

[Changes in urinary immunoreactive-TXB2 and 2,3-dinor TXB2 in man following cardiopulmonary bypass].

We measured urinary levels of i-TXB2, 2,3-dinor TXB2 and NAG following cardiopulmonary bypass (CPB) and studied their clinical significance. Subjects studied were 8 patients undergoing cardiac surgery. In the CABG group, urinary i-TXB2, 2,3-dinor TXB2 and NAG level increased significantly (P less than 0.05) 3hrs after CPB, but decreased on and after the 1st postoperative day. In the DVR group, these levels showed similar changes, but i-TXB2 and NAG levels were significantly (P less than 0.05) higher than those of the CABG on the 1st or 3rd postoperative day. A significant correlation (r = 0.84, P less than 0.05) was observed between NAG and i-TXB2 on and after 2nd postoperative day. The results suggest that urinary i-TXB2 during the period immediately after CPB is derived from platelets and reflects the functional changes in renal urinary tubules, while urinary i-TXB2 level on and after the 2nd postoperative day reflects the function of the renal urinary tubules.

Acetylglucosaminidase↗
PubMed1989

[Visualization of internal mammary artery bypass graft flow using a linear color flow mapping system with a convex type transducer].

To evaluate noninvasively the patency of aortocoronary bypass grafts using the left internal mammary artery (LIMAG), color flow mapping Doppler echocardiography was performed in 23 consecutive patients. There were 22 males and one female. The average number of involved coronary arteries per patient was 2.5 +/- 0.6. The average number of bypassed graft anastomoses was 2.7 +/- 0.9, including 22 isolated LIMAG and one sequential LIMAG. The color flow mapping system used was a linear type 2-D Doppler system (Aloka SSD350) with a convex type transducer. Clear color flow visualization of LIMAG flow was obtained in nine of the 23 patients (39%) studied, with an average peak diastolic velocity of 22.5 +/- 8.7 cm/sec and an average systolic peak velocity of 12.6 +/- 5.7 cm/sec. The coronary angiograms of eight patients were obtained within two weeks after the echocardiographic examinations which demonstrated good graft patency in all LIMAG. Color flow visualization of LIMAG was obtained in four of the eight patients (50%). Although the detection rate was limited, LIMAG flow could be clearly visualized in nearly half the cases studied with stable reproducibility from the transcutaneous echo window. Thus, this technique can be a useful diagnostic means for long-term follow-up of LIMAG and for investigating coronary circulation in the future.

Aged↗
PubMed1988

Effects of propranolol and nitroglycerin on cephalad collateral venous flow in patients with cirrhosis: evaluation using transesophageal real-time two-dimensional Doppler echography.

We used transesophageal real-time two-dimensional Doppler echography (TE2DD) to assess the effects of propranolol (n = 18, 6 mg each) and nitroglycerin (n = 18, 0.5 mg each) on blood flow in the intercostal veins, azygos vein, thoracic aorta, and esophagogastric varices. The primary disease in all of the patients was liver cirrhosis. Propranolol infusion markedly reduced the flow velocity in the varices, intercostal vein, azygos vein, and thoracic aorta (-24%, -41%, -34%, and -24%, respectively). It also significantly reduced the blood flow volume index (BFVI), defined as mean velocity in cm/sec X the square of the diameter in cm2 of both the azygos vein and the aorta (-34%, -21%, respectively). Nitroglycerin infusion did not cause significant changes in the hemodynamics of the above vessels, because the hemodynamic responses to the drug differed from individual to individual. The BFVI of the azygos vein correlated well with the azygos venous flow measured by the conventional thermodilution technique (r = 0.79, p less than 0.01). TE2DD appears to be a useful method for studying the hemodynamics of ascending collaterals in patients with portal hypertension.

Aged↗
PubMed1988

Ultrasonic real time guidance for subclavian venipuncture.

To minimize the complications arising from the subclavian venipuncture, ultrasonically (2-D Doppler) guided puncture was tried upon ten patients. Venipuncture was successful in nine patients whose subclavian vein was visualized by 2-D Doppler. In one patient, the subclavian vein had shifted cephalad, so the subclavian venipuncture was abandoned. Ultrasonically guided venipuncture is thought to be safer and a more sure method for subclavian venipuncture.

Catheterization, Central Venous↗
PubMed1987

Technical and biologic sources of variability in the mapping of aortic, mitral and tricuspid color flow jets.

The quantification of valvular regurgitation by 2-dimensional Doppler imaging depends on identifying and minimizing variability. Aortic, mitral and tricuspid regurgitant jet areas were measured in 50 patients with sinus rhythm or atrial fibrillation to analyze the variables of reading error, valve site, jet size, rhythm and frame rate. One technician recorded jet velocities at 1 frame/cycle at a triggered interval after the electrocardiographic R wave and at frame rates of 7.5 and 15 frames/s. Jet areas from 5 consecutive beats were measured by planimetry by 1 observer. Coefficients of variation between and among groups were compared by analysis of variance; mean values were 14 to 22%. Jets grouped less than 2.5, 2.5 to 5 and greater than 5 cm2 showed the variance of small jets exceeding that of medium and large jets. Aortic regurgitant jets were largest and had smaller variance than mitral tricuspid jets. Variability due to atrial fibrillation and the slower frame rate was marginal. Intraobserver error was 4.3% and interobserver 15.4%. Thus, reproducing jet areas carries a minimum variability of 15% or higher, depending on jet size. Valve site could not be excluded as a separate variable. Comparative quantification is best limited to 1 observer.

Adolescent↗
PubMed1987

Clinical experience with intraoperative Doppler color flow imaging in hepatectomy.

Real-time two-dimensional Doppler echography (2-D Doppler), which permits both structural and blood flow evaluations simultaneously, was applied during hepatectomy in three cases. Intrahepatic portal flow was observed in one case both before and after Pringle's maneuver. Hemihepatic blood flow interruption, which was guided by 2-D Doppler imaging, was tried in two cases. Extrahepatic blood flow was also detected easily with 2-D Doppler techniques. This approach is useful for both anatomic and hemodynamic evaluation during hepatic surgery.

Aged↗