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Biomedical subjects

R Omoto

Publications and source records attributed to R Omoto.

At least 163 records · Page 9Linked to original sources
PubMed1985

Intraoperative color flow mapping by real-time two-dimensional Doppler echocardiography for evaluation of valvular and congenital heart disease and vascular disease.

We have developed real-time two-dimensional Doppler echocardiography, which can display color flow mapping on a two-dimensional echocardiogram. Intraoperative two-dimensional Doppler echocardiography was performed during cardiovascular operations before and after the definitive procedure in 33 patients, 14 with valvular disease, eight with congenital heart disease, and 11 with vascular disease. Its clinical usefulness was evaluated. In patients with valvular heart disease, 13 valve replacements, 10 valvuloplasties, and four untouched lesions were assessed. No paravalvular leakage and three instances of minimal physiological transvalvular leakage from St. Jude Medical valves in the mitral position were noticed. Regurgitation after valvuloplasty was graded by extent of the regurgitant flow. This grading, comparable to postoperative grading, indicated no need for an additional procedure. In congenital heart disease, preoperative diagnoses were confirmed. The effect of the corrective operation was evaluated and no significant leakage or stenosis was found. Interatrial shunt flow was shown to increase after operative balloon atrial septostomy in a patient with dextro-transposition of the great arteries. In 11 patients with dissecting aortic aneurysm, the aneurysm was totally visualized in the operative field, including the structure and flow dynamics. In two patients, the preoperative cineangiographic diagnosis regarding involvement of dissection was corrected. After the vascular procedure, sufficient flow in the major aortic branches was confirmed in all patients and minimal leakage at the suture line was noticed in four patients. In conclusion, intraoperative color flow mapping by two-dimensional Doppler echocardiography has enabled the precise diagnosis and the necessary operation to be determined before cardiopulmonary bypass. It has also allowed the effects of the operation to be assessed before chest closure.

Adult↗
PubMed1984

Dynamic patch artificial myocardium; effects on the residual myocardial function.

Dynamic patch artificial myocardium (D-PATCH) has been developed to replace the damaged left ventricular (LV) wall in severe cardiogenic shock patients with a massive myocardial infarction. This study was undertaken to demonstrate the effects of (1) single D-PATCH support on the global cardiac function (group 1, 12 dogs, whole heart model), (2) single D-PATCH support on the LV function and myocardial metabolism (group 2, 6 dogs, right heart bypass model), and (3) the concomitant support of D-PATCH and aortic counterpulsation (CP) on the regional myocardial function of the residual LV wall (group 3, 6 dogs, right heart bypass model with ultrasonic piezoelectric crystals). In group 1, mean aortic pressure and cardiac output were increased 20-36% (p less than 0.01) and 17-50% (p less than 0.01) respectively, and mean left atrial pressure was decreased 16% (p less than 0.01) by D-PATCH assist. In group 2, under constant preload volume, afterload pressure and heart rate, tension time index (TTI) was decreased 21-26% (p less than 0.01) and myocardial oxygen consumption was also decreased 24-29% (p less than 0.001) by D-PATCH assist. In group 3, although peak LVP was increased by single D-PATCH assist, when heart was assisted concomitantly by D-PATCH and CP peak LVP was significantly decreased (18%, p less than 0.01). Percent LV segmental shortening was not increased by CP assist, but increased 143% (p less than 0.02) by D-PATCH assist. In conclusion, D-PATCH can improve the global LV function and myocardial metabolism of the ischemic failing heart, also improve the regional myocardial function of the residual LV wall. Thus, D-PATCH is effective for the salvage of ischemic myocardium while maintaining the global cardiac function.

Animals↗
PubMed1984

The development of real-time two-dimensional Doppler echocardiography and its clinical significance in acquired valvular diseases. With special reference to the evaluation of valvular regurgitation.

A noninvasive method for real time blood-flow imaging using ultrasound has long been required in the fields of cardiology and cardiovascular surgery. Recently, we developed a method of two-dimensional Doppler echocardiography (hereafter abbreviated as "2-D Doppler") for clinical use which allows us to obtain noninvasively, intracardiac blood-flow images in real time. The main purpose of this paper is to describe the newly developed blood-flow imaging system "2-D Doppler" and to demonstrate its clinical usefulness in acquired valvular diseases, particularly in the evaluation of valvular regurgitation. The device, in principle, combines a conventional pulsed-Doppler system and a newly developed auto-correlator, in which blood-flow images within a given cross section of a beating heart are noninvasively displayed in real time, simultaneously with conventional two-dimensional echocardiograms. The system can provide three kinds of information, direction, velocity and turbulence of blood flow. The 2-D Doppler examinations were carried out on 72 patients with acquired valvular diseases whose diagnoses were confirmed by angiography and/or surgery. Studies were performed comparing the findings of the 2-D Doppler and those of angiography (for aortic and mitral lesions) or with operative findings (for tricuspid lesions) in the quantitative evaluation of valvular regurgitation. Aortic, mitral and tricuspid valvular regurgitation have been quantitatively demonstrated with 2-D Doppler, and, for each value, the severity of the regurgitation showed a high correlation between the findings of 2-D Doppler and of angiography or surgery. In conclusion, we have found that (1) 2-D Doppler is very useful in detecting and estimating the severity of valvular regurgitation, and that (2) 2-D Doppler may replace conventional angiography in some situations.

Aortic Valve Insufficiency↗
PubMed1984

[Clinical advantages of echocardiography in evaluating the left ventricular function].

This communication reported the present understanding on clinical advantages of echocardiography in evaluating practically left ventricular function. To evaluate the global function of the left ventricle, Sarnoff's function curve is clinically applicable, although it is quite difficult to change the preload in most clinical situations. Instead of the plotted function curve, only one functioning point is commonly used for the evaluation, the address of which is determined by the parameters related to preload and cardiac output, respectively. Echocardiography has been the most acceptable method for the clinical evaluation of left ventricular function as the noninvasive nature. The left ventricular size, shape, and function are not independent, but interrelated parameters. In estimating left ventricular volume based on the M-mode echocardiographically measured short axis, several calculation methods have been proposed. Various parameters of left ventricular pump function, such as ejection fraction, percent fractional shortening rate, and mean velocity of circumferential fiber shortening are basically calculated using left ventricular dimensions. However, these calculations are valid only when the dimensions are determined appropriately in the presence of symmetric and uniform contractions of the left ventricle. All these are satisfied, then, ejection fraction and fractional shortening are the most practical parameters for the global function. In ischemic diseases, problems of regional left ventricular function and segmental wall motion analysis are particularly indispensable. The regional function should be differentiated from the global function. It is extremely difficult to display the entire left ventricle in one echocardiographic section, and a combination of the parasternal and apical views can provide an adequate segmental wall motion analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography↗
PubMed1984

[Distribution of ethanolamine oleate after injection in esophageal varices].

The purpose of this study is to know the systemic distribution of sclerosant injected into esophageal varices. Sclerotherapy for esophageal varices was performed for 14 times in 11 patients. The patients were divided into two groups according to the content of sclerosant. Seven patients received a total of 9 intravariceal injections (IVI) with 7 to 30ml of 5% ethanolamine oleate (EO) which contained meglumine diatrizoate (Angiographin) and four patients received a total of 5 IVI with 10 to 20ml of 4.5% EO which contained a 10% volume of 99mTcO-4 solution (EO-99mTc). Distribution of injected materials was observed by X-ray fluoroscopy in the former group and by a scintillation camera in the latter. In both methods most of the sclerosant disappeared from the injected site within five minutes leaving a trace in the varices. Then, the sclerosant was disseminated throughout the body via portal vein. When more than 20ml of sclerosant was injected, some flowed into the azygos vin through the periesophageal vin. After IVI the varices showed atrophic changes, though the sclerosant did not stay in the varices.

Adult↗
PubMed1984

[Real-time two-dimensional Doppler echocardiography in congenital heart disease: its clinical significance].

This study demonstrated the diagnostic usefulness of the newly-developed real-time two-dimensional Doppler echocardiography (2-D Doppler) in congenital heart disease. Among fifty-four patients with congenital heart disease, 18 had ASD; 16, VSD; 6, T/F; 3, PDA; 3, d-TGA; 3, ECD; and 1 each, DORV, PA, PS, Ebstein's anomaly, and ruptured aneurysm of the sinus of Valsalva. Each diagnosis was confirmed by cardiac catheterization and/or surgery. Forty normal cases were subjected as the control. The study cases included 26 adults and 28 children under 15 years old, 13 infants and seven newborns. In 52 cases (96.3%) 2-D Doppler provided diagnostic abnormal intracardiac blood flow images which were compatible with the data of cardiac catheterization and cardiac angiography and/or patients' cardiac anatomy observed during surgery. The blood flow data obtained by 2-D Doppler facilitated determining the appropriate timing of palliative surgery such as the Blalock-Taussig shunt procedure. 2-D Doppler was effective in evaluating medical (pharmaco-echocardiography) and surgical therapy including radical and palliative procedures for congenital heart disease. Thus, 2-D Doppler proved a non-invasive and useful diagnostic method for congenital heart heart disease. Our data suggest that with this technique cardiac surgery can be performed without cardiac catheterization or cardiac angiography in some cases of congenital heart disease.

Adult↗
PubMed1983

A new technique in echocardiology: B-mode to M-mode transformation.

In conventional two-dimensional Echocardiography with sector scanning, M-mode is simultaneously displayed on TV-monitor as the time based ultrasound signals. With conventional system, one end of the cursor-line in B-mode image which indicates the beam direction of M-mode, is always fixed at the point corresponding to the transducer tip. This system has the capability to transform B-mode to M-mode images in any desired direction. However, the time resolution in M-mode is limited to about 33 milli-seconds.

Biometry↗
PubMed1982

Echocardiographic evaluation of left ventricular size, shape and function--advantages and limitations of this method.

Both M-mode and two-dimensional echocardiographies are now available in most institutions and hospitals. Correct understanding of the characteristics of M-mode and two-dimensional echocardiography, such as time resolution, will lead us to a successful application of each of these two displays. Detection of changes in ventricular wall and visualization of segmental wall motion are the most unique abilities in echocardiography. These characteristics permit echocardiographic evaluation of left ventricular function. Left ventricular size, shape and function are not independent parameters, but are interrelated. Various parameters on left ventricular function are calculated from the dimensions of the left ventricle. However, these estimations are valid only when the dimensional determination is optimized and all the assumptions on the model of the left ventricle are satisfied. The simultaneous display system of M-mode and two dimensional echocardiograms on the same frame has been shown particularly useful for an optimization of the measurements. For ischemic heart disease, a knowledge of regional function of the left ventricle and the analysis of segment wall motion are indispensable. One of the major problems in evaluating the left ventricle using echocardiography is a limited acoustic window. A combination of standard parasternal approaches and other approaches is commonly required for obtaining an entire image of the left ventricle.

Cardiac Volume↗
PubMed1980

The comparison of hemodynamic effects of concomitant use of intra-aortic balloon pumping and veno-arterial bypass with atrio-arterial bypass.

Atrio-Arterial Bypass (AAB) and concomitant use of Intra-Aortic Balloon Pumping (IABP) and Veno-Arterial Bypass (VAB) were performed, using 7 dogs with induced cardiogenic shock. AAB was established by draining blood from the left atrium and subsequently returning this blood to the carotid artery. VAB was also accomplished by draining blood from the right atrium and then returning this blood to the femoral artery. And bypass flow rates were set at approximately one third of the baseline cardiac output. Evaluation of hemodynamic effects of concomitant use of IABP and VAB was carried out, compared with AAB. The following findings were obtained. 1) In concomitant use, the left ventricular afterload was decreased to lower level (mSPr and TTI) and the total perfusion flow was increased to higher level than in AAB. 2) In AAB the left ventricular preload (mLAP) decreased to lower level than in concomitant use. 3) In concomitant use and AAB, the left ventricular stroke work decreased to the same level.

Animals↗
PubMed1978

Intra-aortic oxygen distribution during veno-arterial bypass (VAB) without oxygenation in circulatory assist.

Right atrium-femoral artery VAB without oxygenation was performed in 7 dogs at 3 different bypass ratios, 15% 30%, and 45%. Respiration and cardiac output were controlled. Precise intra-aortic distributions of PO2 and O2 saturation were determined by means of a PO2 catheter probe and an oxygen analyzer. The following was concluded: 1) The blood pumped from dog heart produced a narrow "mixing zone" in the mid-aorta with the blood pumped from VAB. The area of the "mixing zone" was in the distal half between renal artery and bifurcation at 15% bypass ratio, in the proximal half between renal artery and bifurcation at 30% bypass ratio, and from celiac artery to below renal artery at 45% bypass ratio. It shifted proximally as the bypass ratio increased. 2) In order to supply necessary oxygen to abdominal viscera, it is recommended that the bypass flow should not exceed 30% of the baseline cardiac output.

Animals↗
PubMed1978

Hemodynamic effects of the concomitant use of intra-aortic balloon pumping and venoarterial bypass without oxygenation in cardiogenic shock.

The concomitant use of INTRA-AORTIC BALLOON PUMPING (IABP) and venoarterial bypass (VAB) without oxygenation (VABsO) was performed in 10 experiments using 6 dogs in cardiogenic shock. VABsO was accomplished with the cricuit from the right atrium to the femoral artery and bypass flow rates were set at approximately one third of the baseline cardiac output. Displacement volume of the IABP balloon was 10 or 20 ml. Evaluation of hemodynamic effects of the concomitant use was carried out, as compared with the single use of IABP or VABsO. The following findings were obtained: (1) In the concomitant use, left ventricular afterload decreased, while mean aortic root pressure increased. Increase in total perfusion flow, decrease in mean left atrial pressure and decrease in left ventricular stroke work were shown more effective than each of the single uses. (2) These results suggest that the concomitant use of IABP and VABsO can be used as a second step assisted circulation when IABP is shown uneffective in the case of severe cardiogenic shock.

Animals↗