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Biomedical subjects

A Kitabatake

Publications and source records attributed to A Kitabatake.

At least 253 records · Page 14Linked to original sources
PubMed1988

Effects of changes in coronary stenosis on left ventricular diastolic filling assessed with pulsed Doppler echocardiography.

To determine the effects of changes in coronary stenosis on left ventricular diastolic filling, diastolic filling was serially examined before and after percutaneous transluminal coronary angioplasty using pulsed Doppler echocardiography in 50 patients with stable exertional angina pectoris. Peak rapid filling velocity and the ratio of peak atrial filling to peak rapid filling velocities were measured from the transmitral flow velocity pattern before and 2 and 9 days after coronary angioplasty. Peak rapid filling velocity increased and the ratio of peak atrial filling to peak rapid filling velocities decreased gradually after coronary angioplasty. The improvement in left ventricular diastolic filling was greater in patients with severe (greater than 90%) coronary stenosis than in patients with mild (less than or equal to 90%) coronary stenosis. In the long-term follow-up period, the improved left ventricular diastolic filling worsened in only 11 patients with marked progression to greater than 90% coronary stenosis. Thus, left ventricular diastolic filling improved gradually after coronary angioplasty, possibly reflecting post-ischemic "stunned" myocardium. Serial examinations of left ventricular diastolic filling with pulsed Doppler echocardiography may be a means of noninvasively assessing the temporal changes in the coronary stenosis and predicting the occurrence of coronary restenosis after coronary angioplasty.

Adult↗
PubMed1988

Alpha 2-adrenoceptor activity exerts dual control of coronary blood flow in canine coronary artery.

To test the hypothesis that alpha 2-adrenoceptor activity exerts a dual control of coronary blood flow, i.e., vasoconstriction and augmentation of the vasodilatory effect of adenosine, four doses of adenosine were infused into left anterior descending coronary artery before and during alpha 2-adrenoceptor stimulation or attenuation in anesthetized open-chest dogs. During a moderate alpha 2-adrenoceptor attenuation (yohimbine or rauwolscine, ic), which did not alter coronary blood flow (CBF) at the base-line condition, the hyperemic response of CBF to infused adenosine was markedly reduced, whereas during the potent attenuation both base-line CBF and adenosine-induced hyperemic CBF were significantly increased. Inversely, the moderate alpha 2-stimulation (0.03 microgram.kg-1.min-1 norepinephrine with prazosin, ic, or 0.04 microgram.kg-1.min-1 clonidine ic, under propranolol pretreatment) augmented the adenosine-induced coronary vasodilation, but the potent alpha 2-stimulation (0.3 microgram.kg-1.min-1 norepinephrine with prazosin ic, or 0.3 microgram.kg-1.min-1 clonidine ic) reduced both base-line CBF hyperemic CBF. In contrast, alpha 2-adrenoceptor activity did not affect papaverine-induced coronary vasodilation. Moreover, the reactive hyperemic flow after a brief coronary occlusion was reduced significantly during the moderate alpha 2-adrenergic attenuation, but it was augmented during the potent one. These results indicate that the moderate activation of the alpha 2-adrenoceptor augments the hyperemic response of CBF to both exogenous and endogenous adenosine, whereas the potent alpha 2-activation may mask this vasodilatory effect through the coronary vasoconstrictive effect.

Adenosine↗
PubMed1988

Value and limitations of Doppler echocardiography in the quantification of stenotic mitral valve area: comparison of the pressure half-time and the continuity equation methods.

Two Doppler methods, the pressure half-time method proposed by Hatle and the method based on the equation of continuity, were used to estimate stenotic mitral valve area noninvasively, and the accuracy of these methods was examined in patients with and without associated aortic regurgitation. Mitral valve area determined at catheterization by the Gorlin formula was used as a standard of reference. The study population consisted of 41 patients with mitral stenosis, and 20 of the 41 patients had associated aortic regurgitation. According to the equation of continuity, mitral valve area was determined as a product of aortic or pulmonic annular cross-sectional area and the ratio of time velocity integral of aortic or pulmonic flow to that of the mitral stenotic jet. Mitral valve area was determined by the pressure half-time method as 220/pressure half-time, the time from the peak transmitral velocity to one-half the square root of the peak velocity on the continuous-wave Doppler-determined transmitral flow velocity pattern. The pressure half-time method tended to overestimate catheterization measurements, and the correlation coefficient for this relation was .69 (SEE = 0.44 cm2). The correlation coefficient improved to .90 when the patients with associated aortic regurgitation were excluded. Mitral valve areas determined by the continuity equation method correlated well with catheterization measurements at a correlation coefficient of .91 (SEE = 0.24 cm2), irrespective of the presence of aortic regurgitation. The ratio of the time-velocity integral or aortic or pulmonic flow to the time-velocity integral of mitral stenotic jet also correlated well with mitral valve area determined by catheterization at a correlation coefficient of .84 (SEE = 0.10).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Regional myocardial perfusion in ischemic heart disease assessed by myocardial contrast echocardiography].

Myocardial contrast echocardiography is a new cardiovascular imaging technique that can be used to evaluate regional myocardial perfusion. Regional myocardial perfusion was studied in 12 patients with normal coronary arteries, 14 patients with old myocardial infarction, four patients with acute myocardial infarction, and 15 patients with effort angina. Conventional two-dimensional echo imaging was obtained during intracoronary injections of relatively small volumes (2 ml) of agitated Urografin-76. The echo intensities were measured before and after injecting contrast agents and the subtraction images were composed by a high-speed image processor (NEXUS 6400). Clear myocardial images were obtained in 10 of 12 the patients with normal coronary arteries, and they reflected well the epicardial arterial architecture by coronary angiography. In cases of old myocardial infarction, the infarcted areas appeared as contrast defects in seven and as slightly enhanced areas in three of the 10 patients. In cases of acute myocardial infarction, contrast defect areas in the myocardial images were less in two cases of successful early coronary thrombolysis or percutaneous transluminal coronary angioplasty (PTCA). However, contrast defects remained unchanged despite good recanalization in one case of delayed PTCA. In cases of effort angina, anginal attacks were successfully induced by rapid atrial pacing in six of the 15 patients. In four of the six patients, contrast enhancement in myocardial imaging during anginal attack decreased more in the endocardial than in the epicardial myocardium, possibly reflecting subendocardial ischemia. It is concluded that this technique can identify regional myocardial perfusion, which is not revealed by coronary angiography, and it is therefore useful for the clinical analysis of ischemic heart disease.

Angina Pectoris↗
PubMed1988

[Mitral valve prolapse: two-dimensional echocardiographic screening in apparently healthy students].

To elucidate the clinical features of mitral valve prolapse in apparently healthy young population, two-dimensional echocardiography was performed in the students (18-22 years) without documented organic heart diseases. Focusing on the systolic dislocation and configuration of the anterior mitral leaflet, a following two-dimensional echocardiographic criterion for grading prolapse was used: Grade I: subjects only with slight slip of the tip of the anterior mitral leaflet (AML) toward the left atrium, Grade II: those with considerable slip of the AML but keeping a normal convex shape in the leaflet body toward the left atrium, and Grade III: those with severe slip of the AML with its ballooning toward the left atrium. Among 2016 students examined, 1507 subjects (74.8%) were judged to be normal, 343 (17.0%) to be Grade I, 141 (7.0%) to be Grade II, and 25 (1.2%) to be Grade III. Of the 25 subjects in Grade III, 20 subjects underwent further examination including a questionnaire about the subjective complaints, physical examination, electrocardiograms at rest and during exercise, Doppler echocardiography and postural tests. Concerning the subjective symptoms, eight subjects had some complaints including chest pain, shortness of breath, dizziness, palpitation, fatigability and synocope, and four of the eight had more than three complaints. Mid-systolic click and a late systolic murmur were audible in four and funnel chest was observed in one. No specific findings were found by electrocardiograms. Mild mitral and tricuspid regurgitations were observed by Doppler echocardiography in four and nine subjects, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

A possible model of the anginal syndrome with normal coronary arteriograms: microembolization of canine coronary arteries.

To investigate whether disseminative coronary embolization with microspheres brings about a pathophysiological mimicking of the syndrome of exertional angina with a normal coronary arteriogram, 25 dogs were studied immediately and 2 weeks after the coronary embolization with microspheres 15 micron [2.5 X 10(5) or 5.0 X 10(5)/regional flow (ml/min)] and 25 micron [2.0 X 10(5)/regional flow (ml/min)] in diameter. Two weeks after embolization with the 15-micron microspheres, the resting coronary blood flow recovered to the control (preembolization) level with the absence of myocardial necrosis, but the coronary flow reserve was significantly lower. In ten dogs receiving the larger dose embolization (5 X 10(5)/regional flow (ml/min], lactate production or a marked decrease in lactate extraction was observed during rapid atrial pacing. In five dogs subject to 25-micron microsphere embolization, however, disseminative patchy myocardial necrosis was observed and the coronary flow reserve remained normal. These results indicate that the chronic state after microembolization with a large dose of 15-micron microspheres mimics the syndrome of exertional angina with a normal coronary arteriogram, whereas 25-micron microsphere embolization does not. Thus, the condition of some patients with a normal coronary arteriogram but with reduced coronary flow reserve may be attributable to microcirculatory disturbances in the coronary arterioles or smaller vessels. Moreover, we observed that the coronary flow at the induction of myocardial ischemia by pacing was much less than the reactive hyperemic flow. This discrepancy may be a characteristic feature in this syndrome.

Angina Pectoris↗
PubMed1987

Alpha 1-adrenoceptor activity regulates release of adenosine from the ischemic myocardium in dogs.

The goal of this study was to test the hypothesis that alpha 1-adrenoceptor activity plays a key role in the release of adenosine from the ischemic myocardium. In 51 open-chest dogs, the left anterior descending coronary artery was perfused through an extracorporeal bypass tube from the carotid artery, and adenosine release into the local coronary vein was measured by the radioimmunoassay technique following the reduction of perfusion pressure for 20 minutes under alpha 1-, alpha 2-, and beta-adrenoceptor attenuations. Adenosine and lactate concentrations in the coronary arterial and venous blood sampled from the perfused area were determined, as well as fractional shortening. In the untreated condition, adenosine release was significantly (p less than 0.01) increased from 1.7 +/- 0.8 (SEM) to 8.8 +/- 1.3 nmol/100 g/min, 20 minutes after the onset of hypoperfusion (coronary blood flow: 28 +/- 2 ml/100 g/min) following the initial overshoot release. Neither beta- nor alpha 2-adrenoceptor attenuation affected the increase in adenosine release during hypoperfusion except for the slight attenuation of the overshoot release by beta-attenuation. In contrast, intracoronary infusions of prazosin and phentolamine during coronary hypoperfusion markedly attenuated (p less than 0.01) release of adenosine (1.8 +/- 0.7 nmol/100 g/min at 20 minutes). The extents of decreases in fractional shortening and lactate production were comparable between the untreated and alpha 1-adrenoceptor attenuation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1987

[Cross-sectional visualization of regurgitant jet by color flow mapping to evaluate aortic regurgitation].

In the noninvasive evaluation of aortic regurgitation by Doppler echocardiography, flow mapping of the aortic regurgitant jet using the long-axis approach is of limited value in cases of combined mitral stenotic lesions. This is because the transmitral flow yields flow disturbances in the left ventricle, making it difficult to identify the extent of the aortic regurgitant jet. To overcome these limitations, the severity of aortic regurgitation was evaluated using the cross-sectional area of the aortic regurgitant jet at the level of the aortic valve as visualized by color flow imaging technique. The study population consisted of 16 patients with aortic regurgitation (10 with pure aortic regurgitation, five with superimposed mitral stenosis, and one with mitral valve replacement). Three normal subjects served as controls. The cross-section of the aortic regurgitant jet was visualized as a mosaic of yellow and blue in all patients with aortic regurgitation, but not in any of the controls. Planimetric measurements of the cross-sectional area of the regurgitant jet (J) and the aortic annulus area (Ao) were performed, and the Doppler parameter, J/Ao, was calculated. As a reference, the aortic regurgitant fraction (RF) was calculated from Doppler measurements of systolic aortic and pulmonary flows (AF and PF); RF (%) = (AF - RF)/AF x 100. The Doppler parameter, J/Ao, correlated well with the Doppler measurement of RF (r = 0.82, p less than 0.005), irrespective of the presence of associated mitral lesions. Thus, the cross-sectional area of the aortic regurgitant jet determined by color flow imaging technique would be a useful estimate of the severity of aortic regurgitation, even in the presence of associated mitral stenotic changes.

Adolescent↗
PubMed1987

Current development in Doppler echocardiography. The real-time two-dimensional Doppler flow imaging system.

Recent advances in ultrasound instrumentations have provided a new Doppler modality capable of displaying the spatial distribution of blood flow velocities by colors on the monochromatic echo image on the real time basis, called the real-time two-dimensional Doppler flow imaging system. With this new Doppler technique, we can noninvasively relate the dynamic flow pattern to the anatomy and the motion of the cardiac structures and can further our understandings of flow dynamics in the circulatory system in health and disease. In clinical cardiology, the Doppler flow imaging technique offeres a quite sensitive approach to the detection of flow abnormalities caused by valvular insufficiency or stenosis and congenital shunt diseases. The spatial distribution of the regurgitant jet flow visualized by the Doppler flow imaging technique provides a semiquantitative approach to the evaluation of the severity of the valvular insufficiency. Furthermore, we can appreciate the spatial and angular orientation of the stenotic or regurgitant jet flow, which allows us to measure the velocity of the jet flow with the optimal beam direction. Though there are some limitations and pitfalls in the Doppler flow imaging system at present, it has provided the mapping of the dynamic distribution of flow velocities, which has never been available with the conventional Doppler technique, and has expanded Doppler capabilities and utilities in clinical cardiology. The Doppler flow imaging system is now widely used as a routine part of noninvasive cardiac examination and is improving its clinical significance.

Coronary Circulation↗
PubMed1986

Clinical assessment of elastic properties of large coronary arteries: pressure-diameter relationship and dynamic incremental elastic modulus.

Vascular elastic properties in vivo (dynamic incremental elastic modulus [Ep(dyn)]) of large coronary arteries were assessed from the pressure-diameter relationships of the large coronary arteries in 46 patients with suspected ischemic heart disease. Ep(dyn) represents the vascular stiffness primarily determined by the organic sclerotic changes of the vascular wall and the vascular smooth muscle tone. Coronary arterial diameter was obtained from the magnified cine coronary arteriograms by using a computerized caliber measurement technique. The mean Ep(dyn) of the left main coronary artery and the proximal portions of the left anterior descending and circumflex coronary arteries with apparently normal angiograms were significantly (P less than 0.01) increased as the number of involved coronary vessels was increased. Mean Ep(dyn) values in multi-vessel disease were comparable with those of dilated segment by the percutaneous transluminal coronary angioplasty, indicating that the vascular sclerotic changes are not localized to the narrowed segments but diffusely distributed to the angiographically normal vascular wall. In 4 patients who had successful percutaneous transluminal coronary angioplasty, Ep(dyn) of the dilated coronary segment showed markedly higher values (0.21-0.30 X 10(6) Nm-2) than the normal values (0.16 +/- 0.06 X 10(6) Nm-2 in left anterior descending coronary artery). In contrast, there was no significant difference in Ep(dyn) values of the angiographically normal left main coronary trunk, proximal portions of left anterior descending and circumflex arteries between patients with and without vasospastic angina. During myocardial ischemia induced by ergonovine maleate, vasospastic response of the non-diseased segment was comparable with that in patients who did not have an anginal attack during the ergonovine test. Thus, in contrast to the sclerotic change, abnormal vasoconstrictive property of the coronary artery may be localized to the diseased segment.

Adult↗
PubMed1986

Role of adenosine in hyperemic response of coronary blood flow in microembolization.

To investigate the pathophysiology of acute embolization of small coronary vessels and the role of adenosine in this abnormality, regional coronary blood flow (CBF), coronary vascular resistance, arteriovenous O2 difference, lactate extraction ratio, and adenosine release were studied in 39 anesthetized open-chest dogs after acute coronary embolization with microspheres of three different diameters (15 +/- 1, 94 +/- 8, and 293 +/- 23 microns). In 16 dogs, the left anterior descending coronary artery was embolized by repetitive injections of 15-microns microspheres, up to 4.4 +/- 0.4 X 10(5)/g myocardium; at this point CBF, determined by the electromagnetic flowmeter at the proximal site of the artery, was reduced toward zero. Up to 37% of total embolization, resting CBF increased to 175 +/- 36% of control; thereafter it decreased almost linearly as the extent of embolization was increased. After embolization, coronary arteriovenous O2 difference was significantly (P less than 0.01) decreased with a marked release of adenosine in the coronary vein. Despite a hyperemic flow response of CBF in the embolized area, myocardial ischemia was not prevented; maximal increase in CBF after 100-microns microsphere embolization (141 +/- 11% of control CBF, n = 6) was significantly (P less than 0.05) less than that in 15-micron microsphere embolization, whereas 300-microns microsphere embolization minimally increased CBF (123 +/- 13%, P greater than 0.1; n = 5). Hyperemic flow remained unchanged for at least 3 h when adenosine was persistently released. Theophylline significantly attenuated this response. These results indicate that in embolization with microspheres less than 300 microns in diameter, hyperemic response of coronary blood flow occurs, probably due to the hyperemia of nonoccluded vessels in the adjacent area of ischemic foci to adenosine released from the ischemic myocardium.

Adenosine↗
PubMed1986

Noninvasive evaluation of aortic regurgitation by continuous-wave Doppler echocardiography.

Continuous-wave Doppler echocardiography was used to examine the aortic regurgitant flow velocity pattern in 32 patients with aortic regurgitation (AR) and 10 patients without AR. The aortic regurgitant flow velocity patterns, characterized by a rapid rise in flow velocity immediately after closure of the aortic valve, high peak flow velocity, and a gradual deceleration until the next aortic valve opening, were successfully obtained in 30 of the 32 patients with AR (sensitivity 94%, specificity 100%). The velocity decline was greater in patients with severe AR; thus, the slope of the velocity decline (deceleration) and the time to decline to half the peak velocity (half-time index) were measured from the flow velocity pattern. The deceleration became greater and the half-time index shortened in accordance with angiographic grading of AR (p less than .01). The deceleration and the half-time index also correlated well with the aortic regurgitant fraction (r = .79, p less than .01; r = -.89, p less than .01). Because the half-time index could be measured easily and independently of Doppler incident angle, it seemed a simple and accurate index of assessing the severity of AR. Thus continuous-wave Doppler echocardiography permitted the noninvasive evaluation of AR.

Adult↗
PubMed1986

Continuous-wave Doppler echocardiographic detection of pulmonary regurgitation and its application to noninvasive estimation of pulmonary artery pressure.

Continuous-wave Doppler echocardiography was used to estimate pulmonary artery pressures by measuring pulmonary regurgitant flow velocity in 21 patients with pulmonary hypertension (mean pulmonary artery pressure greater than or equal to 20 mm Hg) and 24 patients without pulmonary hypertension. The pulmonary regurgitant flow velocity patterns, characterized by a rapid rise in flow velocity immediately after closure of the pulmonary valve and a gradual deceleration until the next pulmonary valve opening, were successfully obtained in 18 of the 21 patients with pulmonary hypertension and in 13 of the 24 patients without pulmonary hypertension. As pulmonary artery pressure increased, pulmonary regurgitant flow velocity became higher; the pulmonary artery-to-right ventricular pressure gradient in diastole (PG) was estimated from the pulmonary regurgitant flow velocity (V) by means of the simplified Bernoulli equation (PG = 4V2). The Doppler-determined pressure gradient at end-diastole correlated well with the catheter measurement of the pressure gradient at end-diastole (r = .94, SEE = 3 mm Hg) and with pulmonary artery end-diastolic pressure (r = .92, SEE = 4 mm Hg). The peak of Doppler-determined pressure gradient during diastole correlated well with mean pulmonary artery pressure (r = .92, SEE = 5 mm Hg). Thus continuous-wave Doppler echocardiography was useful for noninvasive estimation of pulmonary artery pressures.

Adolescent↗
PubMed1986

Cardiotonic activity of a new inotropic agent, 3,4-dihydro-6-[4-(3,4-dimethoxybenzoyl)-1-piperazinyl]-2(1H)- quinolinone (OPC-8212), in the dog with and without beta-blocker and Ca++-antagonist pretreatment.

Hemodynamic effects of a new inotropic agent, OPC-8212 (2(1H)-quinolinone derivative) were studied in anesthetized open chest dogs pretreated with propranolol and diltiazem. Three doses (1, 3 and 10 mg/kg) of OPC-8212 were administered intravenously and the net hemodynamic effect (% change) was obtained by subtraction of the effect of the solvent from the gross effect, since the vehicle has a transient, but significant hemodynamic effect. The maximal inotropic effect occurred 3 minutes after administration: LV dP/dt max and cardiac output (CO) increased by 19 +/- 2.5% and 28 +/- 8.5%, respectively, at 3 mg/kg. These cardiotonic effects were dose-dependent, whereas heart rate, peak LV pressure (PLVP) and mean aortic pressure were minimally changed at any dose. Accordingly, systemic vascular resistance (SVR) decreased in a dose-dependent manner although the decrease was much less than that in administration of isoproterenol. The inotropic effect was not blocked by beta-adrenoceptor blockade (propranolol 1 mg/kg), indicating that the cardiotonic action of this agent is not due to beta-adrenergic stimulation. Thus, this agent could reverse beta-blocker-induced heart failure. During infusion of diltiazem (0.1 mg/kg/min following bolus intravenous administration of 0.5 mg/kg), the increases in LV dP/dt max and CO due to OPC-8212 were similar to those in the control study. In contrast to the effects under beta-adrenoceptor blockade, however, decreased PLVP was restored by OPC-8212. Neither chronotropic nor rrhythmogenic effects were observed in the control or with either pharmacological intervention. These results indicate that OPC-8212 has a potent inotropic action with modest vasodilatory effect even with propranolol or diltiazem pretreatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Beneficial effects of atrioventricular sequential pacing on cardiac output and left ventricular filling assessed with pulsed Doppler echocardiography.

There has been increased interest in the beneficial effects of atrio-ventricular (AV) pacing over ventricular (V) pacing. This study attempted to evaluate the changes in cardiac output and left ventricular filling dynamics when the pacing mode was switched from V pacing to AV pacing. Study population consisted of 26 patients with multiprogrammable AV pacemakers. Cardiac output was determined as a product of echocardiographically determined cross sectional area of the aortic annulus and Doppler-determined velocity integral of left ventricular outflow over systole. Left ventricular peak rapid filling rate (PFR) and peak atrial filling velocity to peak rapid filling velocity ratio (A/R) were determined from measurements at the mitral annulus. Cardiac output showed a significant improvement when the pacing mode was switched from V to AV pacing, and the percent change ranged from 3 to 73% (average 26%). The improvement in cardiac output brought about by AV synchrony was greater in patients with smaller PFR (r = -0.71, p less than 0.01) and larger A/R ratio (r = 0.77, p less than 0.01). On the other hand, PFR was greater with V pacing than with AV pacing. Greater increment of the PFR was produced by the loss of atrial contraction in patients with smaller PFR (r = -0.82, p less than 0.01) and larger A/R ratio (r = 0.76, p less than 0.01). Thus, AV pacing provides a great improvement in left ventricular filling, i.e., cardiac output, which cannot be obtained with V pacing even with the compensatory enhancement of left ventricular rapid filling. These beneficial effects of AV pacing seemed to be greater in patients with impaired left ventricular rapid filling.

Adolescent↗
PubMed1986

[Quantitative integrated backscatter characteristics in the normal and infarcted canine myocardium].

To develop ultrasonic cardiac tissue characterization, serial changes in intensity of backscattered ultrasound from the normal and infarcted myocardium were studied in vitro, with frequency-domain analysis. As an index of backscattered signal intensity, quantitative integrated backscatter [(10 X log-S2/S1)] (dB), S1 and S2 = areas of power spectra of digitized (sample rate = 100 MHz, 8 bits) ultrasonic signals from a perfect reflector and good specimens) were calculated for 60 regions of the myocardium (N = 20, MI = 40) excised from 10 dogs 3 days, 1, 2, and 4 weeks after coronary artery ligation in 2, 3, 3, and 2 dogs, respectively. The myocardial specimens and a stainless steel reflector were mounted at the focal distance of a newly-developed wide-band transducer having a center frequency of 4.0 MHz, in a water bath filled with degassed physiological saline. Tissue concentrations of hydroxyproline (HP) were also established using a HPLC (Hitachi amino acid analyzer model 835). The results obtained were as follows: 1. No significant changes in the integrated backscatter of the normal myocardium were observed throughout the experimental period (3 days = -52.5 +/- 0.7, one week = -53.6 +/- 1.8, two weeks = -51.6 +/- 0.8, four weeks = -52.8 +/- 1.4 (dB) (mean +/- SE). 2. Integrated backscatter of the infarcted myocardium [3 days = -47.3 +/- 0.6, one week = -49.2 +/- 1.3, two weeks = -40.7 +/- 1.3, four weeks = -39.6 +/- 2.0 (dB)] was significantly increased compared with the integrated backscatter of the normal myocardium in the early stage of myocardial infarction, before tissue concentrations of hydroxyproline increased, as well as in the chronic stage of myocardial infarction. 3. Results of histological examinations suggest that minute changes in structure, such as interstitial edema or neovascular proliferations, may be the cause of an early increase in integrated backscatter. The results suggest that quantitative integrated backscatter is a sensitive parameter for detecting both early and old myocardial infarction by cardiac tissue characterization.

Animals↗
PubMed1986

[Coronary thrombolytic therapy in acute myocardial infarction: time dependence of beneficial effects assessed by two-dimensional echocardiography].

To elucidate the effects of coronary thrombolytic therapy in acute myocardial infarction, we observed serially the degree of left ventricular (LV) wall motion immediately after on day 1, and on days 7, 14, 21 and 28 after thrombolytic therapy, in 22 patients with acute anteroseptal myocardial infarction. Base-line coronary arteriography revealed significant lesions in the proximal portions of the left anterior descending artery of all the patients. The patients were categorized according to results of thrombolytic therapy as Group I-a: seven patients with spontaneous or successful recanalization within three hours of onset of chest pain; Group I-b: nine patients with successful recanalization between three and seven hours, with a mean of 4.8 hours from onset; and Group II: six patients in whom thrombolytic therapy was unsuccessful and infarct-related vessels remained totally occluded. The LV wall motion index (WMI) was defined as the sum of point scores for the degrees of regional wall motion at nine segments on serial two-dimensional echocardiograms, and used for quantitative assessments of LV function. Results were as follows: On day 1, immediately after thrombolytic therapy, the WMI of Group I-a was smaller than that of Group II. However, there was no significant difference between Groups I-a and I-b and between Groups I-b and II. These findings suggest that LV function cannot be recovered immediately after recanalization of occluded arteries unless recanalization occurs exceptionally early. Percent improvement of the WMI from days 1 to 28 in Group I-a, 65 +/- 14%, was significantly greater than that in Group I-b, 31 +/- 18%. However, Group II did not show significant improvement in the WMI. The WMI in Group I-a decreased significantly from days 1 to 7 (9.0 +/- 1.6 vs 7.1 +/- 1.8, p less than 0.05); whereas, the WMI in Group I-b showed no significant decrease until day 21. On day 1, the regional wall motion of the antero-apical wall was akinetic or dyskinetic in all patients studied. On day 28, it improved in six of seven patients in Group I-a, while it remained akinetic or dyskinetic in all patients in Groups I-b and II.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗