David E. Guyer

Echocardiographic measurement of right ventricular volume.

The volume of the right ventricle can be determined angiographically from its projections in two mutually perpendicular planes. Echocardiographic techniques for measuring right ventricular volume, however, have been more difficult and less successful. In this study, a method was developed for calculating right ventricular volume from two intersecting cross-sectional echocardiographic views: the apical four-chamber and subcostal right ventricular outflow tract views. First, the areas and lengths of casts of 12 human right ventricles obtained at autopsy were directly measured in the chosen views. Actual cast volumes correlated best with a formula giving volume as 2/3 times the area in one view times the long axis in the other view. The degree of correlation was similarly high for calculations involving the area derived from either view and the length of the roughly orthogonal section. This relationship for right ventricular volume was then confirmed with two-dimensional echocardiographic images of hollow latex molds made from the casts (r = .95, p less than .0001). The significance of these findings is discussed in relation to angiographic results and models of the right ventricle.

Hydrodynamic compression of the right atrium: a new echocardiographic sign of cardiac tamponade.

The relationship of right atrial inversion, a previously undescribed cross-sectional echocardiographic sign, to the presence of cardiac tamponade was examined. We studied 127 patients with moderate or large pericardial effusions. Cardiac tamponade was present in 19 and absent in 104. Four patients with equivocal tamponade were excluded from analysis. Right atrial inversion was present in 19 of 19 patients with cardiac tamponade and 19 of 104 without cardiac tamponade (sensitivity, 100%; specificity, 82%; predictive value, 50%). The degree of inversion as quantitated by the area-corrected curvature did not improve the ability to discriminate between patients with and without cardiac tamponade. However, consideration of the duration of inversion by the right atrial inversion time index (duration of inversion/cardiac cycle length) and an empirically derived cut-off of 0.34 did improve the specificity and predictive value (100% and 100%, respectively) without a significant loss of sensitivity (94%). We conclude that right atrial inversion, particularly if prolonged, is a useful echocardiographic marker of cardiac tamponade that may be of particular diagnostic value when the clinical picture is unclear.

Noninvasive tissue characterization: Diagnosis of lipomatous hypertrophy of the atrial septum by nuclear magnetic resonance imaging

An atrial septal mass was identified by echocardiogram in a patient with multiple subcutaneous lipomas. In order to differentiate the benign condition of lipomatous hypertrophy from myxoma, thrombus and other tumors, nuclear magnetic resonance and computed tomographic imaging were performed. Both techniques identified the adipose nature of the tissue noninvasively, consistent with the diagnosis of lipomatous hypertrophy. Pathologically demonstrated lipomatous hypertrophy in a postmortem heart was similarly characterized by nuclear magnetic resonance imaging.

Congenital aneurysms of the left atrium: recognition by cross-sectional echocardiography.

The two-dimensional echocardiographic features of three patients with congenital aneurysms of the left atrium are described. The aneurysm arose from the left atrial appendage in two patients and from the posterior left atrial wall in one. The aneurysms were characterized by their origin from an otherwise normal left atrium,- a well-defined neck, their position within the pericardial space, and distortion of the left ventricular free wall by the aneurysmal body. The differentiation of these structures from other abnormalities of the left atrium are also discussed. Two-dimensional echocardiography is a safe and reliable method for diagnosing congenital aneurysm of the left atrium, and such studies should be considered in any patient with an otherwise unexplained abnormality on the chest radiograph.

An echocardiographic technique for quantifying and displaying the extent of regional left ventricular dyssynergy

A convenient noninvasive method of mapping the left ventricular endocardial surface has been developed that can be used to display regional dysfunction and calculate the total area of abnormal endocardial excursion from data obtained in two orthogonal apical and three or more short-axis cross-sectional echocardiographic images. Visually identified regions of abnormal systolic function are plotted on end-diastolic, planar endocardial surface maps, and the extent of dysfunction can be expressed either as an absolute area or as a fraction of the total endocardial surface area involved. The extent of the left ventricular surface moving abnormally, calculated with this echocardiographic mapping technique, was compared with two histochemical measures of infarct size in a series of 11 closed chest dogs with acute circumflex coronary artery occlusions. Overall extent of abnormally moving left ventricular wall correlated closely with both the fraction of the endocardial area overlying infarct (r = 0.92, p less than or equal to 0.001) and the fraction of the myocardial volume infarcted (r = 0.86, p less than or equal to 0.001). This suggests that the echocardiographic mapping technique can be used to accurately quantify the global extent of abnormal systolic function in the presence of regional wall motion abnormalities.

Prevalence of aortic valve prolapse with bicuspid aortic valve and its relation to aortic regurgitation: A cross-sectional echocardiographic study

Although aortic valve prolapse (AVP) has been suggested as a cause of aortic regurgitation (AR) in patients with bicuspid aortic valves, neither the frequency of AVP nor its relation to AR in this setting has been defined. To assess these relations, 64 patients with bicuspid aortic valves diagnosed by 2-dimensional echocardiography and 20 normal subjects, similarly distributed according to age and sex, were studied. The presence and degree of AVP were defined using 3 quantitative terms: aortic valve prolapse distance (AVPD), area (AVPA) and volume (AVPV). Each was corrected (c) for patient size with reference to the diameter of the aorta at the level of insertion of the valve cusps. In normal subjects, the AVPDc averaged 0.09 +/- 0.06 (range 0 to 0.16) and the AVPAc averaged 0.08 +/- 0.06 cm (range 0 to 0.15). In patients with bicuspid aortic valves, the AVPDc averaged 0.26 +/- 0.10 (range 0.11 to 0.59, p = 0.00005 vs normal subjects), whereas the AVPAc averaged 0.35 +/- 0.17 cm (range 0.05 to 0.90, p = 0.00005 vs normal subjects). When the AVPDc criteria were used, 81% of the bicuspid valves were abnormal; when the AVPAc criteria were used, 87% were abnormal. The degree of prolapse defined by the AVPVc, which considers both cusp area and degree of apical displacement, was significantly greater for patients with bicuspid aortic valve with clinical AR than for those without (p = 0.008). However, because of the overlap between groups, there was no point at which this measure uniquely separated patients with and without AR.(ABSTRACT TRUNCATED AT 250 WORDS)

A new echocardiographic model for quantifying three-dimensional endocardial surface area

A new technique for quantitatively mapping the three-dimensional left ventricular endocardial surface was developed, using measurements from standard cross-sectional echocardiographic images. To validate the accuracy of this echocardiographic mapping technique in an animal model, the endocardial areas of 15 excised canine ventricles were calculated using measurements made from echocardiographic studies of the hearts and compared with areas determined with latex casts of the same ventricles. Close correlation (r = 0.87, p less than 0.001) between these two measures of endocardial area provided preliminary confirmation of the accuracy of the maps. To further characterize the mapping algorithm, it was translated into computer format and used to map the surfaces of idealized hemiellipsoids. Areas measured with this mapping technique closely approximated the actual areas of idealized surfaces with a wide spectrum of shapes; maps were particularly accurate for ellipsoids with shapes similar to those of undistorted human ventricles. Also, the accuracies of area calculations were relatively insensitive to deviation from the assumed positions of the echocardiographic short-axis planes. Finally, although the accuracy of the mapping technique improved as data from more transverse planes were added, the procedure proved reliable for estimating surface areas when data from only three planes were used. These studies confirm the accuracy of the echocardiographic mapping technique, and they suggest that the resulting planar plots might be useful as templates for localizing and quantifying the overall extent of abnormal wall motion.

Comparison of the echocardiographic and hemodynamic diagnosis of rheumatic tricuspid stenosis

Two-dimensional echocardiography has proved to be reliable in the diagnosis of mitral, aortic and pulmonary stenosis. Its role in the diagnosis of rheumatic tricuspid stenosis is still being defined; therefore, the tricuspid valve echograms of 147 patients with rheumatic heart disease were examined. Thirty-eight of these patients also underwent hemodynamic evaluation. Tricuspid stenosis was defined echocardiographically as diastolic anterior leaflet doming, thickening and restricted excursion of the other two tricuspid leaflets and decreased separation of the leaflet tips. Using these criteria, the sensitivity and specificity of the echocardiogram in detecting tricuspid stenosis were 69 and 96%, respectively, in the group of 38 patients who had both echocardiographic and hemodynamic evaluations. However, when the smaller group of 17 patients who had simultaneous right atrial and right ventricular pressure recordings were considered separately, there was complete agreement between the echocardiographic and hemodynamic data. Thus, the two-dimensional echocardiogram is a sensitive and specific test for diagnosing rheumatic tricuspid stenosis. In addition, these data provided an opportunity to determine the prevalence of tricuspid stenosis in this group of patients with chronic rheumatic valvular disease. Tricuspid stenosis was present in 14 (9.5%) of the total group of 147 patients who had two-dimensional echocardiograms, and in 10 (26.3%) of the 38 who had both echocardiographic and hemodynamic studies. In patients with rheumatic heart disease about to undergo cardiac catheterization, an echocardiographic study should prove useful in making the diagnosis of tricuspid stenosis.

The natural history of regional wall motion in the acutely infarcted canine ventricle

Two-dimensional echocardiography was employed to define the natural history of regional wall motion abnormalities in a canine model of acute experimental myocardial infarction. Serial short-axis two-dimensional echocardiograms were recorded in 11 closed chest dogs before coronary occlusion and 10, 30, 60, 180 and 360 minutes after permanent coronary ligation. Radiolabeled microsphere-derived blood flows were obtained in each study period and the histochemical (triphenyltetrazolium chloride) extent of infarction was determined at 6 hours. Previously published methods were used to quantitate field by field (every 16.7 ms) excursion of 36 evenly spaced endocardial targets. The circumferential extent of abnormal wall motion was followed sequentially using previously published definitions of abnormality: 1) systolic fractional radial change of less than 20%; 2) dyskinesia (systolic bulging) at the point in time (echocardiographic field) in which there is maximal dyskinesia; and 3) correlation with composite normal ray motion falling outside the 95% confidence limits defined in the control period. On the basis of the triphenyltetrazolium chloride staining pattern, the ventricle was divided into five zones: central infarct zone, zone with greater than 25% transmural infarction, total infarct zone, border zones and normal zone. Mean systolic fractional radial change was calculated for each zone and used as an index of the magnitude of abnormal wall motion. Regardless of the definition of abnormality employed, the circumferential extent of abnormal wall motion manifested at 10 minutes after occlusion did not significantly change, even up to 6 hours later. Similarly, 10 minutes after coronary occlusion the three infarct zones and border zones demonstrated significantly reduced systolic fractional radial change. This remained stable over the remainder of the 6 hour study period. It is concluded that once established at 10 minutes after coronary occlusion, the circumferential extent and magnitude of abnormal wall motion do not significantly change in the immediate postinfarct (6 hour) period.

Comparison of high pulse repetition frequency and continuous wave Doppler echocardiography in the assessment of high flow velocity in patients with valvular stenosis and regurgitation.

Continuous wave Doppler echocardiography has proved useful in detecting and quantitating the high velocity flow disturbances that characterize many stenotic and regurgitant valvular lesions. Pulsed Doppler echocardiography, in contrast, is limited in its ability to quantitate the high velocities that are detected. Recently, new pulsed Doppler systems have been developed that employ high pulse repetition frequencies and can theoretically measure higher flow velocities than those measured by the standard pulsed Doppler systems. To determine the ability of high pulse repetition frequency Doppler echocardiography to accurately measure high velocity flow signals in comparison with the continuous wave method, 80 patients undergoing routine echocardiographic examination for the assessment of valvular heart disease were studied using both techniques. A total of 113 high velocity flow disturbances were detected in 68 patients. In 41 instances, the maximal velocities by the two methods were within 0.5 m/s of each other. In 68 of the 113 high velocity lesions, however, the high pulse repetition frequency technique underestimated the peak velocity found with continuous wave Doppler echocardiography by more than 0.5 m/s. Comparison of the peak velocities recorded by the two methods for the total group showed no significant correlation (r = 0.04, p = NS). Comparison of the difference in peak velocities obtained by the two techniques with the maximal continuous wave velocity (n = 94, r = 0.70, slope = 0.71) suggested that the underestimation becomes greater as the peak velocity increases. Fifteen of the study patients with aortic stenosis subsequently underwent catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)