Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038454 (stroke)
147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two-dimensional echocardiography underestimates left ventricular volume compared with cineventriculography. To exclude the influence of difference in heart rate, blood pressure, respiration phases and any effect of the contrast material on left ventricular function, simultaneous studies of two-dimensional echocardiography and cineventriculography-echoventriculography were performed in 46 patients. Apical two-dimensional echocardiograms in the right anterior oblique (RAO) equivalent view were recorded before and during cineventriculography in the 30 degrees RAO projection. End-diastolic and end-systolic volumes (EDV and ESV) were calculated using a disc method with a semiautomatic computer system. The echo transducer position relative to the left ventricular apex and long axis was analyzed. For EDV determined by two-dimensional echocardiography and cineventriculography, the linear regression equation was y = 0.659x + 0.8, SEE = +/- 26.2 ml, r = 0.907. For ESV, the regression equation was y = 0.571x + 17.8, r = 0.938, SEE = +/- 18.6 ml, and for ejection fraction (EF) it was y = 0.606x + 13.0, r = 0.803, SEE = +/- 9.1%. Injection of contrast material resulted in only a small increase of stroke volume, caused by an increase of EDV as analyzed by echoventriculography. In all but two patients, the transducer position was found to be anterior and superior to the left ventricular anatomic apex, as evaluated by filming the echo transducer position during cineventriculography in 46 patients in the 30 degrees RAO projection and in 15 patients consecutively in the 60 degrees left anterior oblique and 30-40 degrees cranial projections. Thus, tangential cuts of the ventricle resulted in underestimation of diameters, long axis and ventricular volumes. These methodologic problems are exacerbated by slice-thickness artifacts. Furthermore, different outlining of left ventricular contour -- outer border of ventricular trabeculae for cine ventriculography and inner border for two-dimensional echocardiography -- seemed to result in underestimation of volume by echocardiography.
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PMID:Echoventriculography -- a simultaneous analysis of two-dimensional echocardiography and cineventriculography. 684 99

Digital subtraction angiography enhances the contrast to background signal, enabling the performance of angiography with reduced doses of contrast medium. The objectives of the present study were (1) to validate the accuracy of digital left ventriculography for measurement of left ventricular volumes and segmental contraction; and (2) to compare the hemodynamic effects resulting from low-and high-dose intraventricular contrast injections. Twenty-eight patients underwent digital left ventriculography, performed by intraventricular injection of 7 ml of contrast medium diluted in saline solution, followed by conventional cineangiography of the left ventricle performed with 45 ml of undiluted contrast medium. Left ventricular volumes calculated from digital ventriculograms correlated well with volumes calculated from conventional ventriculograms: end-diastolic volume (r = 0.97, standard error of estimate [SEE] 23.4 ml; end-systolic volume (r = 0.97, SEE 15.4 ml); stroke volume (r = 0.95, SEE 14.7 ml); and ejection fraction (r = 0.97, SEE 3.8%). Segmental left ventricular contraction, measured as percent chordal shortening of hemiaxes, correlated moderately well (r = 0.81, SEE 11.5%). After injection of undiluted contrast medium, left ventricular systolic pressure decreased (133 +/- 31 to 123.5 +/- 27 mm Hg; p less than 0.01) and left ventricular end-diastolic pressure increased (12.0 +/- 7 to 16.9 +/- 10 mm Hg; p less than 0.001). Left ventricular systolic and end-diastolic pressures did not change significantly after injection of diluted contrast medium, and patients had no discomfort. Thus, digital subtraction angiography permits the performance of left ventriculography with markedly reduced doses of contrast medium, obviating the hemodynamic effects resulting from injection of conventional doses of contrast medium. This new approach to left ventriculography provides high resolution ventriculograms for accurate measurement of left ventricular volumes, stroke volume, and ejection fraction.
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PMID:Validation of the angiographic accuracy of digital left ventriculography. 684 61

Radionuclide gated cardiac blood pool (GBP) imaging was used to quantitatively assess the severity of acute aortic valvular regurgitation produced experimentally in 10 anesthetized dogs. Right ventricular (RV) and left ventricular (LV) stroke counts (end-diastolic minus end-systolic counts in RV and LV regions of interest) were used as indices of the stroke volumes of the two ventricles. Regurgitant fraction (RFGBP) was derived by assuming that an excess of LV stroke counts compared to RV stroke counts was due to regurgitant flow: RFGBP = LV stroke counts - RV stroke counts/LV stroke counts X 100. Regurgitant fraction (RFEMF) was also estimated directly from an electromagnetic flowmeter (EMF) on the ascending aorta. Mean RFEMF was 55.8 +/- 17.9% (+/-SD). Close agreement was found between regurgitant fractions measured by GBP and EMF (RFGBP = 1.09, RFEMF - 4.7%, r = 0.88, p less than 0.001, SEE = 9.98%). The severity of regurgitation from blood pool images also correlated closely with aortic pulse pressure (r = 0.89) and the length of the tear in the aortic valve (r = 0.84). These results suggest that blood pool imaging may be sueful for noninvasive quantification of regurgitant flow in patients with valvular insufficiency.
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PMID:Quantification of aortic valvular regurgitation in dogs by nuclear imaging. 698 48

A nongeometric technique for the determination of left ventricular volumes from the count data derived from gated equilibrium blood pool scans was previously described and validated by the demonstration of an excellent correlation between the derived data and angiographically determined left ventricular volumes. To provide a further prospective evaluation of this method and to validate its ability to determine stroke volume and cardiac output by a technique that is itself independent of geometric assumptions, simultaneous measurements of cardiac output by the thermodilution technique and gated scintigraphy were performed in 21 patients without valve regurgitation or intracardiac shunts. To substantiate the reliability of scintigraphic measurements at high levels of cardiac output, seven patients had multiple measurements of cardiac output at rest and during an infusion of isoproterenol. There was an excellent correlation between thermodilution and scintigraphic values for cardiac output (scan cardiac output = 0.99 thermodilution cardiac output - 0.005 liters/min; n = 31, standard error of the estimate [SEE] = 0.175 liters/min, r = 0.97) as well as between thermodilution and scintigraphic stroke volumes (scan stroke volume = 1.03 thermodilution stroke volume - 2.8 ml; n = 31, SEE = 2.5 ml, r = 0.95). In addition, the relation between scintigraphic and angiographic measurements of left ventricular volumes continued to be excellent: In 15 patients with technically adequate angiograms, scintigraphic left ventricular volume = 0.90 angiographic left ventricular volume + 7 ml (n = 30, SEE = 10 ml, r = 0.91). Thus, this study further validates the nongeometric method of measuring left ventricular volumes with gated scintigraphy and demonstrates its ability to measure left ventricular stroke volume and cardiac output reliably.
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PMID:Direct measurement of cardiac output by gated equilibrium blood pool scintigraphy: validation of scintigraphic volume measurements by a nongeometric technique. 722 52

Recent echocardiographic ABD algorithms can estimate LV volume on-line from a single long-axis plane. The objective of this study was to assess the capability and limitations of transesophageal ABD to estimate stroke volume and cardiac output in patients before and after coronary artery bypass surgery by correlating these data with simultaneous thermodilution measurements. ABD data were acquired on-line from the transverse-plane four-chamber view and the longitudinal-plane two-chamber view and calculated by automated area-length and Simpson's rule formulas for volume. Thirty-three studies were attempted in 18 patients. Technically adequate ABD data were available in all patients from at least one view. Twenty-two (67%) of 33 studies from the four-chamber view and 27 (82%) of 33 studies from the two-chamber view were technically adequate. Cardiac output by all ABD methods was significantly correlated with thermodilution values (r range 0.72 to 0.89; SEE range 0.48 to 0.55 L/min). The two-chamber view underestimated cardiac output slightly, by an average of 0.4 L/min, whereas the four-chamber view consistently underestimated cardiac output by an average of 1.9 L/min. The area-length and Simpson's rule algorithms produced similar results. Biplane transesophageal ABD is an alternative method for estimating cardiac output; the two-chamber view in particular has potential for on-line volume determination.
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PMID:Utility and limitations of biplane transesophageal echocardiographic automated border detection for estimation of left ventricular stroke volume and cardiac output. 803 7

Although color Doppler flow mapping has been used to quantitate the severity of mitral regurgitation, this approach has various limitations. Doppler color flow mapping of a proximal isovelocity surface area (PISA), defined by a blue-red aliasing interface, has been shown in vitro to be accurate for estimating volume flow rate across an orifice. Volume flow rate can be calculated as PISA x aliasing velocity. To evaluate the clinical applicability of the PISA method, we compared the regurgitant stroke volume estimated by the PISA method with the conventional pulsed wave Doppler method in 18 patients with mitral regurgitation. The mean systolic aliasing radius was calculated from color overlayed M-mode (Q/M-mode) images. The mitral regurgitant stroke volume calculated by the PISA method correlated well with that calculated by the pulsed Doppler method (r = 0.89, SEE = 6.0 ml). Thus, the color Doppler PISA method can be applicable to calculating the regurgitant volume in patients with mitral regurgitation.
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PMID:[Quantification of mitral regurgitant stroke volume by the proximal isovelocity surface area method]. 816 37

Stroke volume (SV) and systolic time intervals (STI) were measured automatically using impedance cardiography signals (ICG) and compared with those obtained by pulsed-wave Doppler echocardiography using the apex approach. The comparison was made in 9 healthy male subjects, mean age 24.9 +/- 12.2 years, using recordings of 10 heart cycles simultaneously obtained by the two methods. During measurements the subjects rested in the supine position. There were no differences between mean values of SV determined by the two methods as well as between mean values of ejection time (ET) (p > 0.8 and p > 0.9, respectively). The pre-ejection period (PEP) estimated by ICG was 22 ms longer than that determined by echocardiography (p < 0.001). The relationship between SV values measured by impedance cardiography (SVA) vs those calculated by echocardiography (SVE) was found to be close to the line of identity in the range of measurements. The regression equation for SV was: SVA = 0.784.SVE + 15 (r = 0.69, p < 0.001, SEE = 10.7 ml). We conclude that automatic determination of SV and ET from ICG signals provides results comparable in absolute values with those obtained by the pulsed wave Doppler ultrasonocardiography using the apex approach for subjects remaining in the supine position.
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PMID:A comparison between the automatized impedance cardiography and pulsed-wave Doppler echocardiography methods for measurements of stroke volume (SV) and systolic time intervals (STI). 824 26

Echocardiographic automated border detection can determine the interface between blood and myocardial tissue and calculate left ventricular (LV) cavity area in real-time. The objective was to determine if on-line measurements of LV cavity area by transesophageal automated border detection could be used to determine beat-to-beat changes in stroke volume in humans. Studies were attempted on 9 consecutive patients, aged 66 +/- 8 years, undergoing coronary bypass surgery. Stroke volume was measured by electromagnetic flow from the ascending aorta, and LV cavity area was measured at the midventricular short-axis level. Simultaneous area and flow data were recorded on a computer workstation through a customized interface with the ultrasound system. Recordings were performed during baseline apnea and rapid alterations induced by inferior vena caval occlusions before and after cardiopulmonary bypass. Measurements of stroke area (maximal area-minimal area) were correlated with stroke volume for matched beats. Data were available for analysis on 8 of 9 patients before and on 5 patients after cardiopulmonary bypass for 644 beats. Stroke area was closely correlated with stroke volume both before (mean R = 0.94 +/- 0.03, SEE = 0.33 +/- 0.12 cm2) and after (mean R = 0.92 +/- 0.05, SEE = 0.59 +/- 0.81 cm2) cardiopulmonary bypass. The slopes of these stroke area-stroke volume relations were quite reproducible from before to after cardiopulmonary bypass in the same patient but varied between individual patients. Transesophageal automated border detection has potential for on-line estimation of changes in stroke volume in selected patients.
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PMID:On-line estimation of changes in left ventricular stroke volume by transesophageal echocardiographic automated border detection in patients undergoing coronary artery bypass grafting. 824 52

Flow rate across an orifice can be determined from color Doppler echocardiographic maps of the flow convergence region proximal to the orifice. Different methods have been developed in vitro. The proximal velocity profile method was prospectively evaluated in patients with mitral regurgitation. Color Doppler echocardiography was performed in 74 patients before cardiac catheterization. The increasing velocities within the flow convergence region were determined in an apical plane on the straight line from the transducer to the leak; thus the proximal velocity profile was established and plotted on a nomogram. Instantaneous regurgitant flow rate was derived from the position of the resulting curve in relation to the nomogram's reference curves, which were derived from in vitro measurements. Regurgitant stroke volume was calculated as regurgitant flow rate.regurgitant velocity-time integral/regurgitant peak velocity, using additional continuous-wave Doppler. The 55 patients with angiographic regurgitation had a close association between regurgitant flow rate (0 to 600 ml/s) and angiographic grade (Spearman's rank correlation coefficient = 0.91; p < 0.0001). Regurgitant flow rate did not overlap between grades < or = 2+, 3+ and 4+. In 16 patients, regurgitant stroke volume by echocardiography correlated well with that by the angiography/Fick method (r = 0.88; SEE = 17.1 ml), with a regression line close to identity (y = 0.89x + 12.7 ml). The proximal velocity profile method enables determination of mitral regurgitant flow and estimation of regurgitant volume.
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PMID:Color Doppler echocardiographic determination of mitral regurgitant flow from the proximal velocity profile of the flow convergence region. 842 86

A new method to measure cardiac output using transgastric continuous-wave Doppler was evaluated in 31 consecutive patients undergoing cardiac surgery with simultaneous measurement of cardiac output by the thermodilution technique. A 5 MHz single-plane imaging/5 MHz continuous-wave Doppler transesophageal transducer was used to image the left ventricular outflow tract, aortic valve and ascending aorta from a modified transgastric short-axis plane. The continuous-wave Doppler cursor was aligned parallel with blood flow across the aortic valve to obtain the maximal Doppler velocity spectra. Stroke volume was obtained by multiplying the mean Doppler flow velocity integral by the aortic annulus area, which was calculated from its diameter measured from the esophageal 5-chamber view. The stroke volume was multiplied by heart rate to yield cardiac output. A total of 57 simultaneous thermodilution and Doppler studies were attempted. Doppler data were technically limited for 2 patients both before and after cardiopulmonary bypass and for 3 patients before cardiopulmonary bypass with a result of 50 adequate studies of 57 (88%) attempted. The Doppler-derived cardiac outputs were correlated with the simultaneous measurements of cardiac output by the thermodilution technique. Linear regression analysis revealed a close correlation with R = 0.91, SEE = 0.8 liter/min, and y = 1.01x + 0.2 (p < 0.001). In conclusion, transgastric continuous-wave Doppler across the aortic valve is a promising new technique that may be used in selected patients for accurate measurement of cardiac output.
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PMID:Transgastric continuous-wave Doppler to determine cardiac output. 845 66


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