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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Effective and total left ventricular (LV) stroke volume were assessed in 31 patients with verified aortic or mitral regurgitation, or both, and in 22 patients with normal valvular function using combined first-pass and equilibrium radionuclide ventriculography. The difference between these 2 volumes as a fraction of LV stroke volume was taken as the radionuclide regurgitant fraction. The results were compared with the LV/right ventricular (RV) stroke count ratio and with the angiographic regurgitant fraction according to the method of Sandler and Dodge. Radionuclide regurgitant fraction derived from 2 determinations with a time interval of 1 week showed good reproducibility (n = 15, r = 0.96, SEE = 9.1). Sensitivity was 100% for radionuclide regurgitant fraction and 87% for LV/RV stroke count ratio at equal specificity (100%). Radionuclide regurgitant fraction was more sensitive, especially in severely ill patients, in whom additional RV volume overload led to false-low or false-negative ratios. Angiographic and radionuclide regurgitant fraction showed linear correlation (r = 0.79, p less than 0.001). In contrast, because 5 patients had RV volume overload, only a weak correlation could be noticed between angiography and LV/RV stroke count ratio (r = 0.47, p less than 0.05). Excluding these patients, correlation substantially improved (r = 0.74, p less than 0.001). The combination of first-pass and equilibrium radionuclide ventriculography is a sensitive, specific and well reproducible method for the evaluation of mitral and aortic regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Combined first-pass and equilibrium radionuclide ventriculography and comparison with left ventricular/right ventricular stroke count ratio in mitral and aortic regurgitation. 398 65

We investigated the effect of pacing from the atrium and various ventricular sites on the left ventricular end-systolic pressure-volume relation following autonomic blockade in a total of 10 dogs chronically instrumented to measure left ventricular pressure and determine left ventricular volume from three ultrasonic endocardial dimensions. During ventricular pacing, left ventricular end-diastolic volume, stroke volume, and end-systolic pressure were decreased, while the end-systolic volume was relatively unchanged. Left ventricular end-systolic pressure-volume relations were generated by vena caval occlusions during pacing at a constant rate from the left atria, and the epicardium of the right ventricular free wall, right ventricular apex, and left ventricular free wall. The left ventricular end-systolic pressure-volume relations were described by straight lines for each site (r greater than 0.96 and SEE less than 2.9 mm Hg in all but one instance). Compared to atrial pacing, the left ventricular end-systolic pressure-volume relations were shifted (P less than 0.001) to the right during pacing from ventricular sites. During atrial pacing, the volume intercept of the left ventricular end-systolic pressure-volume relation was 16.0 +/- 7.2 ml (mean +/- SD), and increased to 18.7 +/- 7.8 ml (P less than 0.05) during pacing from the right ventricular free wall, to 19.6 +/- 7.7 ml (P less than 0.05) during pacing from the right ventricular apex, and to 20.0 +/- 7.5 ml (P less than 0.05) during pacing from the left ventricular free wall. These volume intercepts correlated roughly with the extent of dyssynchronous activation as estimated by the QRS duration (r = 0.59 to 0.93) and the time for left ventricular endocardial activation (r = 0.92 and 0.95). During ventricular pacing, the slope of the left ventricular end-systolic pressure-volume relation changed only slightly. Similar results were obtained during pacing from right ventricular endocardial sites. We conclude that alterations of the normal activation sequence produced by ventricular pacing depress left ventricular pumping function independent of loading conditions, as indicated by a rightward shift of the left ventricular end-systolic pressure-volume relation. The extent of this shift appears to be in proportion to the degree of dyssynchronous activation. The decreased stroke volume during ventricular pacing is due both to a decreased end-diastolic volume (decreased preload) and the rightward shift of the end-systolic pressure-volume relation (decreased pump function).
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PMID:Effect of alteration of left ventricular activation sequence on the left ventricular end-systolic pressure-volume relation in closed-chest dogs. 405 4

This study examines the reproducibility of individual radionuclide attenuation factors used in the calculation of cardiac output and left ventricular volume by the nongeometric radionuclide method. Twenty male patients were studied at rest with thermodilution measurements of cardiac output on two separate days. Simultaneous equilibrium radionuclide angiograms were performed and left ventricular stroke volume and cardiac output were determined by the nongeometric method. Individual patient attenuation factors were calculated as the ratio of thermodilution and radionuclide cardiac output measurements at each study. There was a close linear relationship between radionuclide and thermodilution measurements of cardiac output in each study (r = 0.88 study 1, r = 0.97 study 2). A similar relationship was found for measurements of left ventricular stroke volume (r = 0.86, study 1, r = 0.97 study 2). Individual radionuclide attenuation factors ranged from 2.49 to 3.46 in study 1 and from 2.77 to 3.29 in study 2. The individual attenuation factors were reproducible to within 10% in 13 patients and to within 15% in 19 patients. When cardiac output was calculated from the radionuclide data of study 2, by means of individual attenuation factors previously determined in study 1, there was a good correlation with the simultaneous thermodilution measurements of cardiac output (r = 0.92, SEE = 0.38 L/min). Individual radionuclide attenuation factors show little variation in serial studies. Thus the nongeometric radionuclide technique can be used to make accurate serial measurements of cardiac output and left ventricular volume.
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PMID:The reproducibility of nongeometric analysis of cardiac output and left ventricular volume by radionuclide angiography. 406 Dec 54

The purpose of this study is to evaluate four methods of determining left ventricular stroke volume (SV) from aortic valve (AV) and aortic root (AR) M-mode echocardiogram (Table I, formulas 1-4); secondly, to study relations between echocardiographic aortic variables and SV. We studied 20 patients (Pts) in our Coronary Unit, 14 men and 6 women; their ages ranged from 38 to 76 (mean 53.4) years. Seventeen Pts had acute myocardial infarction; two Pts had previous myocardial infarction and heart failure; one Pt had dilated cardiomyopathy and heart failure. Three out of the twenty Pts, had mitral insufficiency (Table II, clinical and hemodynamic data). Patients were studied with high quality M-mode echocardiography. Immediately after the examination repeated measurements of cardiac output by thermodilution technique (TD) were carried out, and values of SV calculated (SV-TD). Twenty-five complete procedures were accomplished. The formulas were applied to every patient's echocardiographic data, and results (SV-ECHO) compared with SV-TD (Table III). Echocardiographic variables, whether single or multiple (terms), were also studied with regard to their relation with SV-TD (Table IV). Mean +/- SD value of SV-TD of the study group was 60.3 +/- 24.7 ml; range 22.7 to 108 ml. Mean +/- SD values of SV-ECHO were as follows: Yeh's formula, based on squared mean AV opening and LVET, 56 +/- 22.6 (ml), r = 0.8278, SEE 12.98; Jacobs' formula, based on aortic box planimetry, 68 +/- 32.5 (ml), r = 0.7129, SEE 23.31.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Methods of determination of stroke volume from M-mode echocardiogram of the aortic valve and aortic root. A comparative evaluation]. 406 79

A system for reconstructing three-dimensional images of the left ventricle from randomly-recorded multiple short-axis two-dimensional images was developed. This system consisted of a real-time phased array sector scanner, a transducer-locating arm system for registering the spatial coordinates of the images, and a digitizer-computer system for digitizing the endocardial edge to display the reconstruction image and to calculate the left ventricular volume. The clinical applicability of this system was assessed by comparing the calculated left ventricular volumes by this system (3DE) with those measured by cineventriculography (LVG) for 10 patients. For end-diastolic volumes (EDV) determined by 3DE and LVG, the linear regression equation was EDV (LVG) = 1.07 EDV (3 DE)-3.4, SEE = 19.0 ml, r = 0.959. For end-systolic volumes (ESV), it was ESV (LVG) = 1.16 ESV (3 DE)-6.0, SEE = 13.1 ml, r = 0.970, and for stroke volumes (SV), it was SV (LVG) = 0.70 SV (3 DE) + 32.3, SEE = 24.5 ml, r = 0.606. This method was considered applicable to clinical non-invasive measurements of left ventricular volumes. Digitized images were easily processed by a computer, and much informations, such as volumes, shapes and wall motion, were assessable.
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PMID:[Three dimensional reconstruction of the human left ventricle from multiple cross-sectional echocardiograms: comparison with biplane cineventriculography using Simpson's rule]. 409 25

A method is described for three dimensional reconstruction of the left ventricle which uses four anatomically defined apical views. It is shown that the algorithms developed for reconstruction and volume estimation provide accurate results when applied to planar views with accurately defined boundaries. The linear regression equation was y = -6.32 + 1.04x, with SEE = +/- 3.4 ml, r = 0.999. For both "in vitro" and "in vivo" studies this method is found to be better than various geometrical models used to estimate volumes from two dimensional tomographic or projection views. The linear regression equation of in vitro fluid volume on volume estimate is y = 8.44 + 0.68x, with SEE = +/- 4.9 ml, r = 0.988. For pooled end diastolic and end systolic volumes (EDV and ESV) determined by three dimensional reconstruction (3-DR) and angiography the linear regression equation is y = 54.50 + 0.50x, with SEE = +/- 33.5 ml, r = 0.670. For stroke volume (SV), the regression equation is y = 21.10 + 0.40x, with SEE = +/- 12.8 ml, r = 0.750, and for ejection fraction (EF) it is y = 1.10 + 0.70x, with SEE = +/- 7.8%, r = 0.840. In patients with ischemic heart disease, the method presented is shown to be better than existing methods of volume estimation. Three dimensional perspective images can be plotted in any orientation as a visual aid to the cardiologist. In vivo studies demonstrate the feasibility of 3-DR, from anatomically defined apical views, in the clinical setting.
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PMID:Three dimensional reconstruction of the left ventricle from four anatomically defined apical two-dimensional echocardiographic views. 633 37

To improve the accuracy of scintigraphic ventricular volume determination, which is limited by photon attenuation between the heart and the gamma camera, a method was developed for directly measuring the photon attenuation of radioactivity delivered as a bolus through a Swan-Ganz catheter into the right atrium. Comparison of the count rate recovered from this bolus with the total ex vivo measured activity determined by imaging an aliquot of the administered activity allowed calculation of the attenuation factor. Left ventricular stroke volumes determined scintigraphically by the count method in gated blood pool studies and then corrected with this attenuation factor correlated well with stroke volumes determined from thermodilution cardiac output and heart rate (r = 0.92; SEE, 6.1 ml). The agreement between the two measurements was markedly less when an average attenuation factor was employed for correction of scintigraphic volumes (r = 0.52; SEE, 14.8 ml). The results indicate that correction for photon attenuation is needed for accurate measurement of left ventricular volumes. Correction of left ventricular counts based on body weight or body surface area improves the accuracy of volume estimates.
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PMID:Left ventricular stroke volume determinations from radionuclide ventriculograms: the effects of photon attenuation. 647 88

A double-lumen polyethylene pigtail catheter (F8, length 100 cm) for the determination of cardiac output (CO) in the arterial system is described. Following femoral insertion of the catheter, 10 ml of ice-cold saline is injected into the left ventricle through the distally ending lumen (0.8 mm2). Through the second lumen (0.8 mm2) which opens 50 cm behind the catheter tip, a thermistor probe (F3, teflon) is advanced into the descending aorta for recording of thermodilution curves. In 21 patients CO was determined first by the Fick method and then by thermodilution in the arterial system. CO by thermodilution correlated favorably with CO by Fick (r = 0.92, SEE 518 ml = 11% of the mean value). There was no systematic deviation from the reference CO. A similarly good correlation existed between stroke volume (SV) by thermodilution and SV by Fick (r = 0.86 SEE 11 ml = 15% of the mean value). Heart rate during thermodilution was 71 bpm, during Fick output estimation 72 bpm (not significant). Following withdrawal of the thermistor probe, simultaneous measurements of left ventricular and aortic pressures can be performed.
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PMID:[A new thermodilution catheter for the determination of heart-minute volume in the arterial system]. 651 61

The main objective of this paper was to assess the efficacy of a laboratory prototype cardio impedance meter, to determine stroke volume in experimental dogs, using Kubicek's classic model. A second objective, complementary to the first, was to evaluate the method itself, under the carefully controlled condition in which cardiac frequency was increased from the initial to the final value. Measurements were performed on ten mongrel dogs (average body weight = 15.2 kg, SD = 4.7), employing the standard thermodilution procedure as reference. Based on a total of 179 determinations (about 18 per animal), the following regression equation was obtained: SVd = (0.36 SVz + 3.94) ml where SVd = stroke volume by thermodilution, SVz = stroke volume by impedance, with a standard error of the estimate SEE = 4.26 ml, a coefficient of variation CV = 32.8%, and 0.84 as correlation r. Thus, the impedance technique overestimated consistently by an average factor in the order of 2. These conclusions were made: In the experimental dog, the impedancimetric method can measure non-invasively directional and relative changes in stroke volume; this permits the effect of several types of maneuvres to be followed on a beat-to-beat basis. The lack of accuracy would require the development of a more sophisticated mathematical model; however, a practical statistical expression for laboratory use is easily derivable, making the determination as if the measurement had been made with the thermodilution procedure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Stroke volume in the dog: measurements by the impedance technique and thermodilution. 666 46

Fourteen patients, aged 1 month to 13 years, with congenital semilunar valve stenosis (11 pulmonary and 3 aortic) were studied for orifice area quantification calculated from a Doppler echocardiographic equation: Area = SV/0.88 X V2 X VET, where SV = stroke volume, V2 = maximal velocity and VET = ventricular ejection time. Results from individual measurements used in this formula and derived area were compared with individual results from cardiac catheterization and valve area derived from the Gorlin formula. Ventricular ejection time by cardiac catheterization ranged from 0.17 to 0.44 second (mean +/- standard deviation [SD] 0.27 +/- 0.09), and by Doppler study from 0.20 to 0.41 second (mean +/- SD 0.29 +/- 0.06) (r = 0.65, standard error of the estimate [SEE] = 0.03, y = 0.149 + 0.528x). Pressure gradient by catheterization ranged from 30 to 125 mm Hg (mean +/- SD 56.6 +/- 33.1), and by Doppler study from 17.6 to 100 mm Hg (mean +/- SD 46.8 +/- 27.9) (r = 0.91, SEE = 8.8, y = 1.23 + 0.904x). Stroke volume was measured by Doppler study simultaneously with cardiac catheterization in nine patients; results at cardiac catheterization with thermodilution measurements (cardiac output/heart rate) ranged from 5.5 to 53.4 cc (mean +/- SD 24.7 +/- 20), and by Doppler study from 5.8 to 46.9 cc (mean +/- SD 23 +/- 18) (r = 0.96, SEE = 3.5). Area quantification was performed in two ways. In Group 1, heart rate-matched stroke volumes from cardiac catheterization were used in the derived equation for Doppler study (all patients). In Group 2, the stroke volume used was that obtained by Doppler study, which was performed simultaneously with cardiac catheterization (nine patients).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Noninvasive quantification of stenotic semilunar valve areas by Doppler echocardiography. 670 77


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