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Biomedical subjects

Y Yokote

Publications and source records attributed to Y Yokote.

At least 91 records · Page 5Linked to original sources
PubMed1986

Doppler ultrasound examination of prosthetic function and ventricular blood flow after mitral valve replacement.

Two-dimensional color Doppler echocardiography enables delineation of the spatial and temporal distribution of blood flow in the heart. In this study, the method was applied for investigation of flow dynamics in multiple planes in the region of prosthetic mitral valves for comparison with that of native mitral valves. In 15 healthy subjects there was normal flow toward the transducer, coded in red, in the left ventricle along the posterolateral wall (left ventricular inflow region) and blue-coded flow away from the transducer in the left ventricular outflow region during diastole. In 40 patients with St. Jude mitral valve prosthesis and 17 with bioprosthesis the flow pattern in the left ventricle was reversed. Mitral inflow was directed against the interventricular septum, accordingly, into the left ventricular outflow region while the outflow pattern was displaced posterolaterally into the left ventricular inflow region during diastole. The angle between the aortic valve ring and the mitral annulus was significantly smaller than in the healthy subjects. The angle between the central axis of the mitral prosthesis and the mitral inflow, which was 0 degrees in healthy subjects, was increased by the medial deviation in particular, in those with mechanical St. Jude prostheses. The maximal transprosthetic velocity, measured in 70 patients, and the maximal pressure gradient calculated according to the Bernoulli equation was substantially greater than the values in healthy subjects. In contrast to findings associated with normally-functioning prostheses, in four patients with prosthetic malfunction there was a diastolic peak velocity of more than 2 m/s as well as marked turbulence in the inflow region.

Bioprosthesis↗
PubMed1986

[Immediate surgical revascularization following unsuccessful coronary thrombolysis: effects on myocardial salvage].

To reduce early and late mortality and morbidity following acute myocardial infarction (AMI), myocardial salvage of the jeopardized areas by coronary thrombolysis (PTCR) during the acute period is effective. However, unsuccessful thrombolysis or severe residual coronary stenosis may result in severe cardiac failure and high mortality in the early and late periods. This study was undertaken to demonstrate the effects of immediate coronary artery bypass surgery (CAB) following unsuccessful PTCR. Thirty-three patients with initial AMI were studied, in whom PTCR was performed within 10 hours of onset of chest pain but it was unsuccessful. In 16 cases (Group I) total occlusion could not be recanalized, and in 17 cases (Group II) subtotal residual stenosis (99% with delayed flow on coronary angiogram) remained. The effects of immediate CAB surgery (Group I-b: 4 cases; Group II-b: 9 cases) for myocardial salvage were evaluated by thallium-201 scintigraphy one to 14 months after onset of AMI, as compared to medical therapy (Group I-a: 12 cases; Group II-a: 8 cases). The thallium uptake in the jeopardized area was categorized as (1) defect (+), (2) decrease, and (3) defect (-). All 12 cases in Group I-a showed defect (+). In Group I-b, one case showed defect (+), one case decreased, and two cases defect (-). In Group II-a, seven of eight cases (88%) showed defect (+) and one case showed decrease; however, in Group II-b seven of nine cases (78%) showed defect (-) and two cases showed defect (+). The effects on myocardial salvage were significantly different between Group a and Group b (p less than 0.001) and Group II-a and Group II-b (p less than 0.01). In conclusion, immediate CAB surgery was superior to medical therapy for ischemic myocardial salvage following unsuccessful PTCR. These results encourage the application of immediate postinfarction CAB surgery in high-risk groups with severe residual coronary stenosis after PTCR.

Aged↗
PubMed1986

[Echo and Doppler cardiographic findings of isolated quadricuspid aortic valve: a case report and a review of the literature].

The two-dimensional and pulsed Doppler echocardiographic features of a case of isolated quadricuspid aortic valve with aortic regurgitation are described. A 62-year-old woman was hospitalized for exertional palpitation and dyspnea. Her physical examination showed the typical findings of aortic regurgitation. Two-dimensional echocardiograms revealed the aortic valve to have four cusps of nearly equal size. The accessory cusp was situated between the right and left coronary cusps. By pulsed Doppler echocardiography, holodiastolic turbulent flow signals were observed in the left ventricle, and the aortic flow pattern showed holodiastolic reverse flow, indicating severe aortic regurgitation. These findings were confirmed by aortography and by surgery. The coronary arteries and pulmonary valve were normal. We attempted a classification of the anatomical variations of the previously reported 34 cases of isolated quadricuspid aortic valves, including our own. They were classified as one smaller (67%), four equal (18%), three smaller (6%), four unequal (6%) and two smaller (3%) types. Twenty of the 34 patients had aortic regurgitation. Bacterial endocarditis and congestive heart failure were the main causes of death.

Aortic Valve↗
PubMed1986

[Visualization of coronary blood flow by transesophageal Doppler color flow mapping].

For noninvasive evaluation of coronary blood flow, 22 patients were examined with transesophageal Doppler color flow mapping within six hours after cardiovascular surgery. The anatomical structure of the left main coronary trunk (LMT) was observed by conventional two-dimensional echocardiography (2-DE) in 20 patients (91%), and color flow of the LMT was visualized in 18 of 21 patients (86%) (one patient had total occlusion). The blood flow in the LMT began in mid-systole, but the flow was observed mainly in diastole. The peak of the flow was observed mainly in late diastole and the range of the peak velocity was 35 to 163 cm/sec (average = 76.9 +/- 31.4 cm/sec). The proximal portion of the right coronary artery (RCA) was observed in 13 patients (59%), and its color flow was visualized in only two patients (9%). In two patients intra-aortic balloon pumping (IABP) assist was performed postoperatively, and the direct effect of the assist on the coronary blood flow was clearly observed by transesophageal Doppler color flow mapping. The peak blood flow velocity of the LMT increased by 32% during the assist. In conclusion, human coronary blood flow can be visualized and evaluated noninvasively using transesophageal Doppler color flow mapping. This technique can be used for future investigation of coronary circulation.

Adult↗
PubMed1986

[Analysis of mitral inflow velocity pattern in relation to left ventricular end-diastolic pressure].

The relationship between mitral inflow velocity patterns and left ventricular end-diastolic pressure (LVEDP) was evaluated using pulsed Doppler echocardiography in 34 cases of heart disease, without significant valvular regurgitation. Flow patterns in 19 of the 34 cases were also examined before and after the elevation of LVEDP by methoxamine infusion, 0.01 mg/kg/min. The ratio of the peak velocities in the atrial contraction phase to that in the rapid filling phase (A/R) and the ratio of mean acceleration rates to peak velocities in the rapid filling phase (ACR/R) were determined from the mitral flow patterns obtained by the apical approach. 1. ACR/R correlated significantly with LVEDP (r = 0.49), but A/R did not. LVEDP in six cases with normal A/R (0.5 to 1.0) was 8.3 +/- 2.9 mmHg (mean +/- SD). Among 19 cases with A/R of 1.0 or more and ACR/R less than 13 sec-1, LVEDP showed 10.2 +/- 3.8 mmHg. In eight cases with A/R of 1.0 or more and ACR/R of 13 sec-1 or more, LVEDP was 17.9 +/- 6.2 mmHg. The average value of LVEDP in two cases with A/R less than 0.5 was 18.5 mmHg. 2. When the LVEDP was elevated after methoxamine infusion, A/R within normal range increased in five of six cases and decreased in the remaining case. A/R more than 1.0 decreased in 10 of 11 cases and ACR/R tended to increase with increasing LVEDP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

[The role of hypertension in apical hypertrophy].

Recent advances in echocardiography have revealed that hypertension causes several types of cardiac hypertrophy. We classified hypertensive patients by type of cardiac hypertrophy, and evaluated left ventricular function and the severity of hypertension. The subjects consisted of 257 hypertensive patients, 13 patients with cardiac hypertrophy, and 95 normotensive controls. The hypertensives were classified in four groups: no hypertrophy, concentric hypertrophy, asymmetrical septal hypertrophy (ASH), and asymmetrical apical hypertrophy (AAH). The normotensive patients with cardiac hypertrophy included nine with ASH and four with AAH. Cardiac functions in these patients were determined by echocardiography, RI-angiocardiography and cardiac catheterization. The results were as follows: Among 257 hypertensive patients, the incidence of concentric hypertrophy, ASH, and AAH was 53%, 10%, and 4%, respectively. In patients with AAH and hypertension, the hypertensive blood pressure levels and hypertensive organ involvements were mild. The blood pressures of most of these patients fell to the normal range after admission. The cardiac index and left ventricular systolic function (FS, mVCF, and ejection fraction) were significantly higher in AAH with hypertension than in the other hypertensive groups or in the normotensive controls. The hypertensive patients showed lower E-F slopes and higher A/E ratios than the normotensive controls, as well as the normotensive patients with ASH or AAH. Cardiac function did not differ appreciably between normotensive AAH and hypertensive AAH. Left ventricular dimension and left ventricular end-diastolic volume index were larger in AAH with hypertension. The total peripheral resistance of the hypertensive AAH was significantly lower than that of the hypertensives with concentric hypertrophy (p less than 0.01), though it was higher than that of the normotensive AAH (p less than 0.01). It was, therefore, concluded that mild hypertension observed in patients with AAH may be the result of regulatory mechanisms in the hyperkinetic states.

Adolescent↗
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

[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

Amino-acid sequence of feather keratin from fowl.

The amino acid sequence of a single polypeptide chain, B-4, from fowl feather barbs has been determined. The B-4 chain was found to consist of 96 amino acid residues and to have a molecular weight of 10206 in the S-carboxymethylated form. The N terminus of this protein was an N-acetylserine residue. The B-4 protein contained seven S-carboxymethylcysteine residues, six of which are located in the N-terminal region (residues 1-26), and other one in C terminus. The central region of the peptide chain was rich in hydrophobic residues. There were homologous amino acids at 66 positions in the sequences of the feather keratins of fowl, emu and silver gull. The variation (substitution, deletion and insertion) in sequence was found to be localized in both terminal sections of the polypeptide chain. The B-4 protein structure was predicted to contain beta-sheet (about 30%), turn and random-coil-like structure, and no alpha-helix. beta-Sheet structure is mostly located in the central region (residues 22-70). On the other hand, both terminal regions are almost devoid of secondary structure.

Amino Acid Sequence↗
PubMed1983

[Echocardiographic findings in 3 cases of mucopolysaccharidosis].

Mucopolysaccharidosis (MPS) has been shown to cause cardiac involvements. However, echocardiographic features of MPS were not well understood. We examined echocardiographic findings in three adult patients with MPS. The diagnosis was confirmed by measuring urinary acid mucopolysaccharide and alpha-L-iduronidase activity in the white blood cell and skin fibroblast. The age ranged from 29 to 54 years. Two patients were Scheie syndrome (MPS I-S) and one was suspected to be Maroteaux-Lamy syndrome (MPS VI). All patients had a systolic heart murmur suggestive of aortic stenosis, and one had an additional apical systolic murmur consistent with mitral regurgitation. The echocardiogram revealed the following findings; 1) an abnormal thickening of all aortic leaflets with reduced valve opening in all cases, 2) diffuse and marked thickening of the mitral leaflets, chordae and papillary muscles, no upward motion of the posterior mitral leaflet in spite of reduced E-F slope (13, 23 and 17 mm/sec, respectively), and slight narrowing of the mitral orifice, and 3) a slightly thickened and dilated left ventricle (IVS: 11, PW: 12, EDd: 58, and ESd 44 mm) in the case with Maroteaux-Lamy syndrome. The last finding was probably due to deposition of mucopolysaccharide in the myocardium, because the coronary arteriogram in this case did not demonstrate any significant lesions. The echocardiographic characteristics in our adult MPS cases were similar to those reported in infant or juvenile cases with Hurler syndrome (MPS 1-H) or Hunter syndrome (MPS II). However, our Maroteaux-Lamy patient may be the first case, in which myocardial involvement by mucopolysaccharide was suggested echocardiographically.

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↗