Accuracy of volume determination by two-dimensional echocardiography: defining requirements under controlled conditions in the ejecting canine left ventricle

The accuracy of two-dimensional echocardiographic left ventricular volume measurement in an isolated heart preparation was tested using Simpson's reconstruction of progressively fewer short-axis cross sections of known location. Echocardiographic images from five ejecting hearts submerged in a special tank were obtained under conditions designed for maximal accuracy of echocardiographic volume assessment. Echocardiographic determinations of 52 volumes at various times throughout the cardiac cycle were compared, by least-squares linear regression, with simultaneous direct-volume measurements by volumetric chamber (range 9.4-44.8 ml). Echocardiographic and direct measurements correlated well for all numbers of cross sections from 1-19 (r = 0.84-0.97); however, variability of direct volume predicted from a given echocardiographic measurement increased nonlinearly as the number of cross sections per heart decreased, and was especially large when three or fewer cross sections were used (SEE = 4.6-7 ml). The accuracy of echocardiographic measures was compared for each number of cross sections per heart, varying from one to 19; accuracy was defined as the mean absolute difference between echocardiographic and direct measurements of volume, ejection fraction, and maximal rate of ejection. The accuracy of echocardiographic measurements was significantly reduced with fewer than four cross sections per heart for ventricular volume, three cross sections for ejection fraction, and five cross sections for maximal rate of ejection. In light of what appears to be required for accurate echocardiographic volume measurement in this controlled, ejecting, noninfarcted, in vitro preparation, additional cross sections may be required in intact animals and human subjects, especially in those with diseases that cause ventricular asymmetry or regional dysfunction.     

Non-invasive left ventricular volume determination by two-dimensional echocardiography.

Twenty patients undergoing routine left ventricular single-plane angiography have been investigated by an ultrasonic triggered B-scan technique to provide a two-dimensional cross-sectional image of the left ventricle in end-systole end-diastole. An area-length method has been used to establish the correlation between the angiographic and the echocardiographic assessments of left ventricular chamber volume (r equals 0.88) and ejection fraction (r equals 0.81). Differences between the two techniques are discussed, and it is concluded that in approximately 80 per cent of patients triggered B-scanning may provide a safe, non-invasive, and convenient technique for the determination of volumes and certain functional parameters, especially in patients with dilated hearts and irregular left ventricular shape, where M-scanning is known to be less reliable.     

Approaches to determination of left ventricular volume and ejection fraction by real-time two-dimensional echocardiography.

Left ventricular volumes and ejection fraction were derived from real time two-dimensional echocardiographic images (2 DE) and single plane (RAO) left ventricular cineangiograms in a series of 50 patients. Prospective application of a series of 6 alternate algorithms showed that a modified Simpson's rule approach using mitral and papillary muscle cross sections and an apical four chamber view provided the best 2 DE - angiographic correlations: for end-diastolic volume r = 0.82, SEE = 39 ml; for end-systolic volume r = 0.90, SEE = 29 ml and for ejection fraction r = 0.80, SEE = 0.09. The large SEE for volume determination indicates that further refinements are necessary to predict left ventricular volumes adequately; however, ejection fraction can be derived with an accuracy which allows practical clinical decisions in patients with satisfactory 2 DE images.     

Accuracy of volume measurement by conductance catheter in isolated, ejecting canine hearts

We evaluated the accuracy of the recently reported technique of estimating intraventricular volume by measurement of intracavitary electrical conductance in six isolated, ejecting, canine left ventricles. Left ventricular volumes were measured directly by a previously validated servosystem that employed an electroconductive balloon placed in the left ventricular cavity. The volume measured continuously by the balloon method (Vbal) was compared with that estimated by the conductance method (Vcath). For this test, the hearts were made to eject and fill physiologically by the use of a previously described computer-simulated arterial loading system. Complex ejection and filling patterns were created by stimulating the atrium mechanically, which resulted in irregular arrhythmatic contractions spanning a wide range of volumes. We found that there was a highly linear relationship (r2 = .982 +/- .014) between Vbal and Vcath: Vcath = 0.82 (+/- .05) Vbal + 26.7 (+/- 11.8) ml. Despite the wide variation in the offset term of this relationship among the different hearts, the offset within a given heart was predicted within 3.5 ml by a previously detailed "dilution" method that is applicable to the heart in situ within a closed thorax. Thus, since the offset term is obtainable in situ, the conductance method provides a signal that is proportional to the actual volume. To determine whether right ventricular volume influenced the accuracy of left ventricular measurement, we compared the relationship between Vcath and Vbal obtained with right ventricular volumes of 0 and 30 ml. Increasing the right ventricular volume shifted the relationship upward by less than 3 ml in the working range.(ABSTRACT TRUNCATED AT 250 WORDS)     

Simultaneous contrast imaging of the left ventricle by two-dimensional echocardiography and standard ventriculography

Simultaneous contrast two-dimensional echocardiograms and contrast ventriculograms were analyzed for 19 cardiac cycles in 6 patients. Ventriculographic volume was underestimated by 40 ± 4.5% (p <.001) by the contrast echocardiograms, despite good correlation (r = 0.88). Discrepancies could not be assigned to changes in volume between studies nor to a lack of precise endocardial definition. Simultaneous imaging demonstrated that the ultrasonic transducer was located 33° cephalad to the cardiac apex. Although angiographic volume was severely underestimated, ejection fraction (r = 0.93) and stroke volume (r = 0.90) could be calculated from two-dimensional echocardiograms using regression equations.     

Pseudoaneurysm of the left ventricle complicated by Salmonella typhimurium infection: Recognition by two-dimensional echocardiography

A patient is described with a large posterior left ventricular pseudoaneurysm complicated by Salmonella typhimurium infection. M-mode echocardiography displayed a massive echo-free space behind the posterior left ventricular wall, and two-dimensional echocardiography specifically defined the orifice and saccular contour of the false aneurysm. These findings were confirmed by cardiac catheterization and surgery. The unusual features of Salmonella endovascular infection and the noninvasive methods to detect left ventricular pseudoaneurysms are reviewed.     

Technique for measuring regional two-dimensional finite strains in canine left ventricle

We developed a technique to measure regional two-dimensional deformations in the myocardium. Three piezoelectric crystals were implanted in a triangular array in the left ventricular anterior midwall in six anesthetized dogs. Each crystal was used in a dual function, to both transmit and receive ultrasonic signals from the other two crystals. In this manner, the three segment lengths of the crystal triangle throughout the cardiac cycle were simultaneously recorded. The orientation of the crystal triangle with reference to the left ventricular long and minor axes was determined. The orientation and three segment lengths of the crystal triangle were used to calculate the circumferential strain E11, the longitudinal strain E22, the in-plane shear strain E12, and the mutually perpendicular principal strains E1 and E2. Also, the orientation of the first principal direction or the in-plane angle was determined, which was defined as the angle between the first principal direction (E1) and the circumferential direction (0 degree). This information fully describes the regional two-dimensional myocardial deformations. This technique was applied to measure regional myocardial deformations at three different left ventricular end-diastolic pressures (LVEDP) of 2 +/- 1 (mean +/- SD), 8 +/- 1, and 17 +/- 2 mm Hg. The first principal direction at end-systole was oriented away from the circumferential direction at low LVEDP (-43 +/- 21 degrees) but became progressively closer in each animal to the circumferential direction as LVEDP increased to mid (-26 +/- 18 degrees) and high (-14 +/- 13 degrees) levels. The end-systolic ratio E11/E1 was 0.6 +/- 0.2 at low LVEDP, but increased toward unity in each animal to 0.9 +/- 0.1 at mid and high LVEDP. Thus, at low LVEDP, the greatest systolic deformation occurred in a direction different from the circumferential orientation. Therefore, circumferential strain measurements (E11) significantly underestimated the greatest systolic deformation (E1). However, as LVEDP increased, the first principal direction rotated closer toward the circumferential orientation, and circumferential strain measurements adequately estimated the greatest systolic deformation. Nevertheless, the presence of significant amounts of shortening along either the longitudinal (E22) or the second principal direction (E2) in the midwall necessitated the use of the two-dimensional method. The change in end-diastolic configuration as LVEDP increased from 1 +/- 1 to 16 +/- 1 mm Hg was also examined. Unlike the end-systolic data, the end-diastolic first principal direction did not deviate significantly from the circumferential direction at any LVEDP.(ABSTRACT TRUNCATED AT 400 WORDS)     

Instantaneous pressure-volume relation of the ejecting canine left atrium

To characterize the pump function of the left atrium, we determined the instantaneous pressure-volume relation of the isolated supported left atrium. A physiologic after-loading system for the low-pressure atrium was created by coupling it to a real-time computer-simulated ventricle and a simulated venous impedance network via a volume servo-pump. In 10 atria loaded with such systems, multiple isochronal sets of pressure-volume data were collected from many ejecting or isovolumic contractions obtained under a constant inotropic state, and the time-varying elastance, E(t), as well as the volume-axis intercepts, VO(t), were calculated. E(t) is the ensemble of slopes, and VO(t), the volume-axis intercepts resulting from the linear regression of instantaneous pressure on instantaneous volume at multiple instants throughout the cardiac cycle. The systolic portion of the left atrial E(t) was insensitive to loading conditions, as was VO(t), which, in addition, proved to be similar to the right atrial and right ventricular VO(t) waveforms in its time dependence. These results indicate that E(t) and VO(t) adequately represent the instantaneous pressure-volume relation of the left atrium in systole irrespective of the mode of contraction. Whatever the underlying mechanism might be, the load insensitivity and similarity of the basic shape of the left atrial E(t) among different atria suggests that the characterization reflects fundamental features of left atrial contraction.     

Double-chambered left ventricle in echocardiography

In this article, we describe a double-chambered left ventricle (LV) in a 37-year-old man. Its accessory chamber attached to the inferior and posterior wall of LV, and had normal systolic contraction without any regional wall motion abnormality. A double-chambered LV was suspected on echocardiography and confirmed by cardiac computed tomography scanning and cardiac magnet resonance imaging. Our aim is to accentuate the value of echocardiography in this rare anomaly     

Prognostic value of two-dimensional echocardiography before aneurysmectomy in anterior aneurysm of the left ventricle

The prognostic value of echocardiographic apical 4 chamber recordings was assessed retrospectively in 18 patients who underwent left ventricular aneurysmectomy following anterior wall myocardial infarction. After an average follow-up period of 2 years, 7 patients had died or remained in functional Classes III or IV (Group 1) and 11 patients had satisfactory clinical outcomes (Group 2). There were no significant clinical or coronary angiographic differences between the two groups. The left ventricular surface area, transverse diameter and fractional shortening of the surface were also comparable in the two groups. The surface area of the aneurysm was greater in patients in Group 1 (37.4 +/- 11.8 cm2 vs 21.1 +/- 15.8 cm2, p less than 0.05). However, the more discriminating parameters were those related to the non-aneurysmal contractile zones (NACZ). Patients in Group 1 had a smaller relative surface area of the NACZ than those in group 2; 6 of the 7 patients in Group 1 had NACZ of less than 40 per cent of the left ventricle compared with none of the patients in Group 2 (p less than 0.001). In addition, the function of the NACZ was significantly worse in Group 1: surface fractional shortening: 9.6 +/- 10.2% vs 32.6 +/- 8.3% (p less than 0.001); ejection fraction: 20.7 +/- 9.1% vs 41.6 +/- 6.1% (p less than 0.001). All patients in Group 1 and none in Group 2 had ejection fractions of the NACZ of less than 30 per cent. Therefore, the apical 4 chamber view provides valuable prognostic information in patients who are candidates for surgical resection of left ventricular anterior wall aneurysms.     

Diagnosis of left ventricular thrombi by two-dimensional echocardiography.

Sixteen patients had two-dimensional echocardiographic diagnosis of the presence or absence of left ventricular thrombi and anatomical, radiological, or clinical confirmation of the diagnosis. Eleven patients had positive diagnoses, which were confirmed in 10 and possibly incorrect in one. Five other records were reviewed because the patients had undergone aneurysmectomy after two-dimensional echocardiograms: three were true negative and two were false negative studies.     

End-systolic pressure-volume relations of isolated ejecting rabbit left ventricles after quick diastolic volume changes

The aim of the study was to investigate the influence of quick diastolic volume changes on systolic performance of ejecting left ventricles. To measure left ventricular systolic performance the maximum ratio of ventricular pressure (P) and volume (V) was calculated on beat-to-beat basis when the diastolic loading conditions were varied in different ways. These end-systolic P-V (P-VES) points were obtained from both isovolumic and ejecting contractions. A deviation from the P-VES relation is thought to result from factors changing the inotropic condition of the heart. When steady state isovolumic and ejecting P-VES data were collected linear P-VES relations were found. The relations coincided when stroke volumes were not too large. When the diastolic volume was quickly changed (ie 10 to 20 ms) late in diastole, the P-VES points of the resulting contractions showed a significant deviation from the steady state relation (p less than 0.001). This deviation was dependent on the magnitude of the volume step. After quick volume infusions the heart ejected to end-systolic volume (ESV) values that were smaller than expected from the steady state P-VES relation and the end-systolic pressure (ESP) was larger. After quick volume withdrawals ESV values were larger and ESP was smaller than expected. The magnitude of the effect was not dependent on the preset basic diastolic volume if the volume changes were considered as fractions end-diastolic volumes (EDV). It is concluded that when diastolic volumes are varied just before stimulation, a significant deviation of the P-VES point from the steady state P-VES relation is found in the following contraction. This phenomenon suggests an alteration in the inotropic state of the heart.     

Intravascular volume dependency of left ventricular mass calculation by two-dimensional guided M-mode echocardiography

BACKGROUND: Increased left ventricular mass (LVM) is an independent risk factor for cardiovascular morbidity and mortality, and may be used for risk stratification. Two-dimensional echocardiography, the most commonly used technique for estimation of LVM, uses the third power of the left ventricular internal diameter (LVID) for the calculation. OBJECTIVES: To determine whether a decrease in intravascular volume after dialysis may cause inaccurate estimation of LVM by echocardiography. METHODS: Thirty-eight patients undergoing hemodialysis due to chronic renal failure constituted the study group (14 women [37%] and 24 men [63%], mean age +/- SD 38.7+/-10.9 years). LVID, and interventricular and posterior wall thicknesses were measured by two-dimensionally guided M-mode echocardiography. Stroke volume and cardiac output were calculated using left ventricular outflow tract diameter and the pulsed-wave Doppler time-velocity integral obtained from left ventricular outflow tract. LVM was calculated by using Devereux's formula, and was indexed for body surface area and height. All echocardiographic parameters were measured or calculated before and after dialysis (on the same day), and then compared. RESULTS: There were no significant changes in wall thickness; however, LVID, LVM, the LVM/body surface index and the LVM/height index significantly decreased after dialysis (P<0.001 for each parameter). There was a significant correlation between the change in LVID and the change in LVM (P<0.001, r=0.59). Stroke volume and cardiac output also decreased significantly after hemodialysis (P<0.001 for each parameter). CONCLUSIONS: Intravascular volume-dependent change in LVID causes inaccurate estimation of LVM, so volume status should be kept in mind, especially in serial assessment of LVM.     

Comparison of single-plane and biplane volume determination by two-dimensional echocardiography 1. Asymmetric model hearts

In asymmetric model hearts volume was estimated by two-dimensionalechocardiography (2-dE) and radiography, and the results comparedto directly measured volume in the range from 10 to 320 ml (n= 22). The disc method, and the area-length and ellipsoid methodswere used for both single-plane and biplane calculations. Whenbiplane 2-dE measurements were calculated by the disc methodand compared with directly measured volumes the regression equationwas acceptably linear. For single-plane calculations, no linearitywas found. For the disc method, the regression equation wasgiven by y = 0.91x + 8.4, the correlation coefficient (r) was0.989, and the standard error of estimate (s.e.e.) was ±12.8 ml. The confidence interval was 0.85 to 0.98. With thearea-length method the regression equation was y = 0.93x + 7.4,r = 0.987, s.e.e. = ± 14.0 ml. For the ellipsoid method,the regression equation was y = 0.89x + 1.2, r = 0.966, s.e.e.= ±22.0 ml. With radiographic biplane calculations compared to directlydetermined values the regression equation was also found tobe linear. For single-plane calculations such linearity wasnot found. For the disc method the regression equation was y= 0.99x + 5.9, r = 0.991, and s.e.e. = ±12.6 ml. Theconfidence interval was 0.93 to 1.06. For the area-length methodthe regression equation was y = 1.01x + 9.0, r = 0.987, s.e.e.= ±15.0 ml, and for the ellipsoid method y = 0.97x –3.3, r = 0.992, s.e.e. = ±11.2 ml. Thus, 2-dE is an accurate method for volume determination inasymmetric model hearts using biplane calculations and the discmethod. Area-length and ellipsoid methods seemed to be lessaccurate. Compared to radiography, 2-dE yielded similar correlation coefficientsand s.e.e.s. Whereas 2-dE slightly underestimated model heartvolume (–4.5 ± 14.7 ml, NS), radiography overestimatedthe volume (+5.7 ± 12.3 ml, P<0.05). The mean differencebetween 2-dE and radiography was 10.2 ± 21.2 ml, P<0.05).These results ought to be taken into account when left ventricularvolume determinations are done in patients with coronary arterydisease.     

Infarction of the right ventricle. Contribution of two-dimensional echocardiography

This study, based on 39 cases, confirms the value of two-dimensional echocardiography in the diagnosis of right ventricular infarction during the acute phase. This diagnosis is confirmed by the presence of abnormalities of the segmental kinetics always present in the inferior wall and less frequently in the anterior wall. The inferior part of the septum is affected in two thirds of cases. Right ventricular dilation is frequently observed, but is not constant. Two-dimensional echocardiography has a diagnostic sensitivity similar to that of isotope ventriculography, but greater than that of haemodynamic investigations. Finally, apart from the easy demonstration of complications (tricuspid incompetence, septal rupture, intracardiac thrombosis), two dimensional echocardiography can be used to evaluate right ventricular function.