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S Nanto

Publications and source records attributed to S Nanto.

At least 73 records · Page 4Linked to original sources
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

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

[Collateral circulation during exercise-induced angina: evaluation by coronary angiography].

The pathophysiological significance of coronary collateral vessels remains controversial, despite previous intensive studies. We performed the multistage supine ergometer stress test for 26 patients with effort angina and collaterals. The changes in the collaterals were observed during each anginal attack by coronary angiography before and after intravenous nitroglycerin. The collaterals of 21 patients disappeared or diminished during exercise-induced angina before nitroglycerin administration, and were unchanged in the remaining five cases. However, the collaterals of all patients after nitroglycerin administration were unchanged or increased during exercise-induced angina. Considering there were no significant changes in pulmonary arterial end-diastolic pressures during angina before and after nitroglycerin administration, a pressure gradient between the donor and recipient coronary arteries was suggested as being related to the patency of the collaterals. These results suggested the following: 1. It is not appropriate to postulate that the collaterals visualized at rest may remain unchanged during exercise-induced angina. 2. It is not reasonable to conclude that exercise accelerates the development of collateral circulation. 3. One favorable effect of nitroglycerin administration is the prevention of exercise-induced ischemia via collateral circulation.

Adult↗
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↗
PubMed1986

[Pulmonary arterial end-diastolic pressure noninvasively estimated by continuous wave Doppler echocardiography].

To estimate pulmonary arterial end-diastolic pressures noninvasively, we measured the pulmonary regurgitant flow velocity by continuous wave Doppler echocardiography in 17 patients with pulmonary hypertension (pulmonary arterial end diastolic pressure greater than or equal to 18 mmHg) and in 23 patients without pulmonary hypertension. Pulmonary regurgitation was successfully detected by continuous wave Doppler echocardiography in 14 of the 17 patients with pulmonary hypertension and in 14 of the 23 patients without pulmonary hypertension. The end-diastolic pulmonary artery-to-right ventricular pressure gradient was estimated from the Doppler-determined pulmonary regurgitant flow velocity by means of a simplified Bernoulli equation. The Doppler-determined end-diastolic pulmonary artery-to-right ventricular pressure gradient correlated well with the catheter measurement (r = 0.94). It also correlated well with the pulmonary arterial end-diastolic pressure (r = 0.92). Thus, continuous wave Doppler echocardiography was useful in estimating noninvasively pulmonary arterial end-diastolic pressures.

Adolescent↗
PubMed1985

Functional significance of transient collaterals during coronary artery spasm.

Coronary collateral vessels appear transiently during vasospasm. To examine the functional role of such collaterals in acute myocardial ischemia, regional coronary flow was determined in patients who showed isolated total spasm in the proximal left anterior descending coronary artery associated with (n = 7, group I) and without (n = 9, group II) collaterals, which were donated by the nonspastic right coronary artery during ergonovine provocative test. Aortic pressure and heart rate were not significantly different in the 2 groups before and during spasm. During vasospasm, the levels of pulmonary artery end-diastolic pressure were significantly higher in group II (19 +/- 2 mm Hg, mean +/- standard error) than in group I (15 +/- 1 mm Hg, p less than 0.05). Under these conditions, great cardiac vein flow (GCVF) measured by thermodilution was markedly reduced in group II (from 60 +/- 4 ml/min to 37 +/- 4 ml/min, p less than 0.01), whereas GCVF was slightly reduced in group I (from 56 +/- 4 ml/min to 51 +/- 4 ml/min), indicating that residual GCVF was greater in patients with than in those without collaterals (p less than 0.05). The calculated coronary collateral resistance index during vasospasm was significantly lower in group I (2.06 +/- 0.18 mm Hg min/ml) than in group II (2.91 +/- 0.30 mm Hg min/ml, p less than 0.05). Total left anterior descending coronary artery spasm with collaterals was less frequently associated with ST elevation in the precordial electrocardiogram recorded during spasm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Comparison of coronary hemodynamic and cardiac metabolic alterations during coronary artery spasm associated with ST segment elevation or depression.

Coronary vasospasms are usually indicated by ST elevation or depression in the electrocardiogram (ECG). To test the hypothesis that ST elevation represents more severe myocardial ischemia than does ST depression, we determined the coronary sinus blood flow (CSBF) and the transcardiac lactate extraction ratio (LER) in 19 selected patients who had focal vasospasms in the left anterior descending artery. In 10 patients, ergonovine (0.11 +/- 0.02 mg, mean +/- SEM) provoked severe (total or subtotal) coronary vasospasm with ST elevation. Under these conditions, CSBF significantly decreased (from 97 +/- 8 ml/min to 79 +/- 5 ml/min, p less than 0.01) with a marked reduction in LER (from 29 +/- 5% to -14 +/- 6%, p less than 0.01). In contrast, 10 vasospastic events with ST depression after ergonovine (0.15 +/- 0.04 mg, NS) were recognized as mild spastic narrowing or severe spasms with well developed collateral circulation. Alteration of CSBF was significant in only a few patients and the overall CSBF response was non-significant (from 106 +/- 12 ml/min to 103 +/- 13 ml/min). The reduction in LER in this group was less pronounced than those in patients with ST elevation (p less than 0.05). These results indicate that coronary vasospasm with ST elevation may be related to the more pronounced reduction in coronary blood flow accompanied by more severe myocardial ischemia. Such observations may support the contention that some ischemic events associated with ST elevation or depression can be interpreted as a continuous spectrum of vasospastic disorders.

Adult↗
PubMed1985

[Continuous wave Doppler echocardiography as a noninvasive evaluation of aortic regurgitation].

Continuous wave Doppler echocardiography permits measurement of high blood flow velocity, which is not obtained by conventional pulsed Doppler echocardiography. In this study, continuous wave Doppler echocardiography was used to measure aortic regurgitant flow velocity, and the utility of this method in evaluating aortic regurgitation (AR) was examined. Continuous wave Doppler recordings of the left ventricular outflow were obtained with the guidance of the long-axis two-dimensional echocardiogram from the apex in 20 patients with AR and 10 without AR. In 18 of the 20 patients with AR, Doppler signals of regurgitant flow were successfully detected. The recorded regurgitant flow velocity pattern had characteristic contours: the regurgitant flow was greater than 1.8 m/sec in velocity immediately after aortic valve closure, and gradually decelerated until the next ventricular systole. The Doppler half time index, which was the time profile to decline to 0.5 of the peak velocity, was significantly shortened in accordance with the degree of AR (p less than 0.01). Thus, continuous wave Doppler echocardiography is a simple, useful method for the noninvasive evaluation of AR.

Adult↗
PubMed1984

Hemodynamic and metabolic effects of vasodilator therapy for heart failure in acute myocardial infarction.

Hemodynamic effects of vasodilator agents (molsidomine, nitroglycerin, isosorbide dinitrate or prostaglandin I2) were studied in 53 patients with acute myocardial infarction. In 20 of these patients, effect on cardiac metabolism were also studied. Patients were divided into four groups according to the Forrester subset and hemodynamic effects of these agents were evaluated by the cardiac index (CI)-preload (PAEDP) relationship. In patients of Forrester subset II and IV, vasodilators were capable of producing a considerable reduction in preload without a significant decrease in cardiac output. However, in patients of Forrester subset IV, five of six patients had only a minimal improvement in cardiac performance with vasodilator therapy because of a severe pump failure. In these patients, a combination therapy with dopamine was necessary to maintain the cardiac output. In patients with Forrester subset III, vasodilator therapy decreased cardiac index and preload was also reduced. Thus, for these patients vasodilators could not be indicated but volume infusion may be indicated. In patients with Forrester subset I, although vasodilator therapy decreased cardiac output, coronary sinus flow and myocardial oxygen consumption were also decreased, indicating that the vasodilator therapy is also beneficial for patients even without heart failure because of the protective effect of unloading on ischemic myocardium. Three nitrate agents, i.e., molsidomine, nitroglycerin and isosorbide dinitrate, demonstrated the similar effect on hemodynamics; mean blood pressure and PAEDP decreased by 7-10% and 20-29%, respectively, while systemic vascular resistance was not significantly decreased. In contrast to nitrates, PGI2 decreased mean blood pressure and systemic vascular resistance significantly, whereas a decrease in PAEDP was minimal.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1983

Validity of contrast hyperemia for clinical assessment of coronary flow reserve: the optimal dose of contrast medium and reproducibility of the technique.

The dose-response relation of contrast medium-induced hyperemic response in coronary blood flow (contrast hyperemia) was investigated to determine the optimal dose of contrast medium (CM, Urografin-76) for the assessment of coronary flow reserve in man. The great cardiac venous flow (GCVF) was determined with the continuous thermodilution method during the contrast hyperemia induced by the intracoronary injection of CM of three different doses, ie, 2, 4, and 6 ml/60 kg of body weight, into left coronary artery. Submaximal coronary vasodilation could be obtained by intracoronary injection of 4 ml of CM with minimal changes in systemic hemodynamics. The contrast hyperemia with this dose of CM was reproducible and also closely correlated with that obtained during pacing-induced angina. Thus, we conclude that the contrast hyperemic technique with intracoronary injection of 4 ml of Urografin-76 could be a reliable method to assess the coronary flow reserve.

Blood Circulation↗
PubMed1983

Transient collateral augmentation during coronary arterial spasm associated with ST-segment depression.

To examine the possible existence of collateral circulation during coronary artery spasm, we attempted to visualize the transient appearance of collateral vessels that could serve to salvage otherwise jeopardized ischemic areas. In three patients with vasospastic angina, total spastic obstruction of a major coronary artery was associated with transient collateral augmentation, which was supplied by the nonspastic artery during anginal period associated with ST-segment depression. These collateral vessels disappeared when the angina and ST changes resolved after nitroglycerin administration. These findings suggest that the collateral blood supply could transiently occur through preexisting vessels to perfuse the ischemic area during coronary artery spasm and that such collateral flow could have a role in preventing transmural myocardial ischemia, resulting in a lesser degree of ischemia associated with ST-segment depression.

Adult↗
PubMed1983

Arteriographic features of angina pectoris associated with ST segment depression during coronary arterial spasm.

To examine the angiographic features of vasospastic angina associated with ST segment depression, we attempted to analyze the coronary arteriograms of 12 patients who exhibited ST segment depression during the ergonovine provocative test. Right and left coronary arteriograms were obtained successively within a short period when the ergonovine administration revealed ST segment depression. Eight out of 12 patients showed non-total spastic obstructions in one of the major coronary arteries. Among them, a collateral augmentation was found only in one patient. Two cases exhibited the well-developed collateral channels during non-anginal periods and in one case a collateral blood supply was reduced by the spasm occurred in the donating artery. In another one, the collateral circulation did not change during anginal period. Three out of 4 patients who showed total spastic obstructions demonstrated transiently augmented collateral circulation which was supplied by the non-spastic artery. These findings may indicate that ST segment depression during coronary artery spasm could attribute to a subendocardial ischemia caused by an incomplete occlusion of large coronary artery and transient reduction or augmentation of collateral blood flow.

Adult↗
PubMed1983

Acute effects of intravenous trapidil on hemodynamics, coronary circulation and myocardial metabolism in man.

The acute effects of intravenous trapidil on hemodynamics, coronary circulation and myocardial metabolism were evaluated in 19 patients (Group I: 10 patients of chest pain syndrome; Group II: 9 patients of coronary heart disease). The heart rate increased (p less than 0.05) and aortic pressure decreased (p less than 0.01) during a 6-min study period. Pulmonary arterial end-diastolic pressure decreased slightly in both groups and cardiac output increased prominently in Group II. Myocardial oxygen consumption did not change significantly 3 and 6 min after trapidil injection. Coronary sinus flow increased slightly (statistically not significant) despite a decrease in aortic pressure, and thus, coronary vascular resistance decreased significantly in both groups. Coronary A-V O2 difference decreased 3 min after trapidil injection and no significant change in the lactate extraction ratio was observed. The diameter of the left main coronary artery increased by about 6% after an administration of trapidil. These results suggest that trapidil has the beneficial effect of coronary vasodilation and it increases cardiac output, despite a decrease in the preload, without a significant increase in myocardial oxygen consumption. The latter may be due to an afterload reduction effect of this drug.

Aged↗