Echocardiographic determination of left ventricular stress-velocity relations.

The time course of left ventricular (LV) circumferential stress and fiber shortening velocity (Vcf) were determined at 20 msec intervals in 30 patients from simultaneous recordings of LV pressure (micromanometer) and LV dimensions (echography). In 12 patients with normal LV function, endocardial and midwall maximal (max) Vcf, Vcf at peak stress, and endocardial mean Vcf were significantly greater than in eight patients with myocardial disease. Peak stress was less in the normal subjects (mean equal 241 gl/cm2, range 180 to 310 g/cm2) than in those with myocardial diseases (mean equals 371 g/cm2, range 280 to 513 g/cm2). Vcf was reduced in five out of seven patients with chronic LV volume overload, while peak stress ranged from normal in three to increased in four. Max Vcf, mean Vcf, and peak stress were normal in three patients with chronic LV pressure overload; Vcf at peak stress was normal in two. Good correlation was observed between angiographic determinations of mean Vcf and endocardial max Vcf, Vcf at peak stress and mean Vcf. Induced changes in preload in five patients (dextran infusion at constant heart rate) produced a 12.2 per cent increase in peak stress (P small than 0.05), and insignificant changes in max Vcf (3.7 per cent increase, P = NS), in Vcf at peak stress (5 per cent decrease, P smaller than 0.05), in mean Vcf (0.7 per cent increase, P = NS). Increasing afterload with angiotensin in seven patients (peak stress increased by 45 per cent, P smaller than 0.01) reduced max Vcf, Vcf at peak stress and mean Vcf by 33 per cent, 39 per cent respectively. Lowering afterload in one patient (amyl nitrite) produced an increase in Vcf. Improvement in Vcf was observed in all instances during positive inotropic stimulation (isoproterenol in three normals, digoxin in four with myocardial disease). Thre response of endocardial and midwall Vcf to loading and contractility were similar. In man Vcf is an index of myocardial contractility which is affected minimally by changes in preload but responds inversely to changes in afterload. Its sensitivity to acute afterload changes may, at times, limit its clinical applicability.     

Echocardiographic studies of left ventricular wall motion and dimensions after valvular heart surgery

Echocardiograms obtained from 50 patients after valvular heart surgery (in 33 cases within 2 months of the procedure) were examined to study patterns of interventricular septal motion and left ventricular dimensional changes. Preoperative echograms were available in 28 cases. Before and after mitral commissurotomy septal motion and left ventricular diameters as well as the percent systolic shortening of the echocardiographic transverse axis were within normal limits. Before operation, aortic and mitral regurgitation were associated with increases in end-diastolic and end-systolic diameters, septal motion and percent systolic shortening of the left ventricular diameter. Septal dyssynergy, defined as paradoxical motion or marked hypokinesia, was seen within 2 months of operation in 91 percent of patients after aortic valve replacement and in 42 percent after mitral valve replacement. Of subjects studied more than 2 months postoperatively, none with mitral valve replacement and only 33 percent with aortic valve replacement manifested septal dyssynergy. After valve replacement for aortic or mitral regurgitation there were significant decreases in end-diastolic diameter, septal excursion and total and percent left ventricular systolic shortening. Two subjects not having valve replacement also demonstrated paradoxical septal motion postoperatively. The cause of septal dyssynergy after valvular surgery was not apparent although the use of cardiopulmonary bypass was an essential condition.We conclude that echocardiography can be utilized to follow up changes in left ventricular wall motion and dimensions after surgery for valvular heart disease, and that it may be of value in assessing the early and late postoperative results.     

Test of reliability of echocardiographic estimation of left ventricular dimensions and volumes.

This test is based on the incompressibility of myocardium, which dictates that left ventricular wall volume remains constant throughout the cardiac cycle. The volumes occupied by the left ventricular cavity, by ventricular wall plus cavity, and hence by ventricular wall alone were estimated, both at end-systole and at end-diastole, from ecocardiographic measurements of cavity transverse dimension and wall thickness. Wall volumes were determined by assuming an ellipsoid shape (the major axis being predicted from aggression equations relating angiocardiographic and echocardiographic cavity dimensions) and also by the cube method. A discrepancy between systolic and diastolic wall volume estimates indicates either that the measurements of ventricular dimensions were unreliable or that the assumptions of ventricular geometry involved in the volume calculations were incorrect. Studies were made on 60 subjects. Using the ellipsoid formula, values for wall volume ranged from 66 to 719 ml; systolic and diastolic wall volumes correlated closely (r = 0-96, mean difference = 6-8 +/- 0-9 (SEM) %) supporting the reliability of the echocardiographic dimensions and estimates of cavity and wall volume. In the 12 patients with very large end-diastolic cavity transverse dimensions (6-5 to 8-6 cm) however, correlation was less good (r - 0-81, mean difference = 14-3 +/- 2-3 (SEM) 5). Using the cube method, which does not allow for the changing relation between minor and major cavity axes with increasing cavity size, wall volumes were greater (76 to 986 ml) but correlation was similar (r = 0-94, mean difference = 7-1 +/- 0-9 (SEM)%). Having established that it is possible to obtain close agreement between wall volumes determined at different points in the cardiac cycle, this test can be used to assess the reliability of echocardiographic left ventricular dimensions and volume estimates in individual subjects.     

Test of reliability of echocardiographic estimation of left ventricular dimensions and volumes.

This test is based on the incompressibility of myocardium, which dictates that left ventricular wall volume remains constant throughout the cardiac cycle. The volumes occupied by the left ventricular cavity, by ventricular wall plus cavity, and hence by ventricular wall alone were estimated, both at end-systole and at end-diastole, from ecocardiographic measurements of cavity transverse dimension and wall thickness. Wall volumes were determined by assuming an ellipsoid shape (the major axis being predicted from aggression equations relating angiocardiographic and echocardiographic cavity dimensions) and also by the cube method. A discrepancy between systolic and diastolic wall volume estimates indicates either that the measurements of ventricular dimensions were unreliable or that the assumptions of ventricular geometry involved in the volume calculations were incorrect. Studies were made on 60 subjects. Using the ellipsoid formula, values for wall volume ranged from 66 to 719 ml; systolic and diastolic wall volumes correlated closely (r = 0-96, mean difference = 6-8 +/- 0-9 (SEM) %) supporting the reliability of the echocardiographic dimensions and estimates of cavity and wall volume. In the 12 patients with very large end-diastolic cavity transverse dimensions (6-5 to 8-6 cm) however, correlation was less good (r - 0-81, mean difference = 14-3 +/- 2-3 (SEM) 5). Using the cube method, which does not allow for the changing relation between minor and major cavity axes with increasing cavity size, wall volumes were greater (76 to 986 ml) but correlation was similar (r = 0-94, mean difference = 7-1 +/- 0-9 (SEM)%). Having established that it is possible to obtain close agreement between wall volumes determined at different points in the cardiac cycle, this test can be used to assess the reliability of echocardiographic left ventricular dimensions and volume estimates in individual subjects.     

Echocardiographic assessment of left ventricular performance before and after marathon running

Echocardiography was used to indirectly assess the effects of marathon running on myocardial performance. Thirteen marathon runners (mean +/- SEM:30 +/- 1.6 years) were submitted to a resting echocardiographic examination before racing and during early recovery from marathon racing. Indices of left ventricular performance were computed from M-mode recordings of left ventricular dimensions and aortic valve motions. Comparison of basal and post-marathon indices of left ventricular performance showed no significant differences in either pre-ejection period (PEP), left ventricular ejection index (LVEI), fractional shortening (% delta D), ejection fraction (EF), or mean rate of circumferential fiber shortening (mVcf). Cardiac output (Qc) computed from left ventricular end-diastolic (LVEDV) and end-systolic volumes (LVESV) were significantly higher following marathon running (4.9 +/- 0.4 to 6.7 +/- 0.7 L/min) because of a marked increase in resting heart rate (HR) (58 +/- 3 to 76 +/- 3 bpm). A significant decrease in systolic blood pressure (118 +/- 4 to 108 +/- 3 mm Hg), associated with a slight reduction in calculated total peripheral resistance was also observed after the race. These circulatory adjustments probably reflect thermoregulatory activity that allows a greater blood flow to the skin for heat dissipation, as well as persistence of reactive muscle hyperemia. Echocardiographic evidence suggests that marathon running does not lead to marked impairments in left ventricular performance. However, the absence of change in the end-systolic volume, despite a marked reduction in cardiac afterload, may suggest a slight alteration in contractility that could not be detected with the use of echocardiography.     

Echocardiographic determination of left atrial volumes in children with congenital heart disease.

The feasibility of determining left atrial volumes (LAV) from LA echo dimensions was assessed in 36 children (group I) with normal cineangiographically determined LAV and 16 children (group II) with LAV overload. Conventional LA echo dimensions, obtained within 24 hours of cardiac catheterization, were compared to the angiographic LA anterior-posterior minor axes (LAmA) and LAV. There was excellent correlation betweeh the LA echo dimensions and the LAmA. In all patients, the LA echo less than LAmA, the differences being more pronounced in group II. Good correlations were found between the LAV and the LA echo, and were expressed by the equations LAV = 7.5 LA echo1.8 (r = .85) and LAV = 8.1 LA echo2.1 (r = .86) for groups I and II, respectively. Changes in LA configuration with volume overload were shown to cause a disproportionate increase in LAmA compared to the other LA dimensions and the LA echo dimension, thus necessitating the separate regression equations. Echo LA to aortic ratios were 0.86 +/- 0.11 and 1.21 +/- 0.23 (mean +/- SD) for groups I and II, respectively. This method of estimating LAV can be useful in the management of left-to-right intracardiac shunts and mitral regurgitation in infants and children.     

Nongeometric determination of left ventricular volumes from equilibrium blood pool scans

This study assesses the utility of a scintigraphic, nongeometric technique for the determination of left ventricular volumes. Accordingly, gated blood pool scintigraphy and cineangiography were performed within a 24 hour period in 22 patients. Scintigraphic volume measurements were calculated from individual frames of a modified 35 ° left anterior oblique projection using an algorithm designed to consider (1) the background-corrected left ventricular activity normalized for activity per milliliter of peripheral venous blood; (2) total study time; (3) number of frames acquired per cardiac cycle; and (4) percent of the cardiac cycle acquired. Angiographic volumes were calculated by the area-length method and the Kennedy regression equation. There was an excellent correlation between scintigraphic and angiographic methods for all volume measurements grouped together (r = 0.985, standard error of the estimate [SEE] = 14.6 ml) as well as for segregated end-diastolic volumes (r = 0.985, SEE = 16.2 ml) and end-systolic volumes (r = 0.988, SEE = 14.7 ml). Prospective testing of the independent ability of scintigraphy to estimate ventricular volumes was provided for by studying an additional 13 patients, and good agreement was found between scintigraphic and angiographic determinations of left ventricular end-systolic and end-diastolic volumes. Thus, radio nuclide techniques, which are independent of geometric assumptions, may be utilized for the quantitation of left ventricular volumes.     

Echocardiographic diagnosis of left ventricular thrombi

Left ventricular thrombi have not been commonly recognized by M-mode or by cross-sectional echocardiographic techniques despite their frequency at postmortem examination in patients dying of cardiovascular disease. We discuss two patients, with left ventricular thrombi recognized echocardiographically and confirmed by pathologic and/or angiographic evaluation, whose M-mode and cross-sectional echocardiographic abnormalities add to the variable spectrum of appearance of left ventricular thrombi. The sensitivity and specificity of echocardiographic techniques in the diagnosis of intracardiac thrombi are discussed.     

Comparative angiographic right and left ventricular volumes

Comparative angiographic right and left ventricular volumes and right and left ventricular ejection fractions have been reported in the same normal infants and children. This relationship was assessed in adult patients to determine if these pediatric observations persist in later life. Seventeen adults, who had both right and left ventricular angiograms and who had no demonstrable organic heart disease, were studied. Right ventricular end-diastolic volume ranged from 54 to 98 (76 +/- 14, mean +/- SD) cc/m2 and left ventricular end-diastolic volume ranged from 48 to 90 (70 +/- 12) cc/m2; p less than 0.03. Right ventricular end-systolic volume ranged from 22 to 47 (33 +/- 8.0) cc/m2 and left ventricular end-systolic volume ranged from 13 to 34 (22 +/- 5.3) cc/m2; p less than 0.00005. Calculated right ventricular stroke volume ranged from 31 to 60 (43 +/- 8.3) cc/m2 and left ventricular stroke volume ranged from 29 to 70 (48 +/- 11) cc/m2; p = NS. Calculated right ventricular ejection fraction ranged from 0.48 to 0.62 (0.57 +/- 0.04) and the left ventricular ejection fraction ranged from 0.57 to 0.84 (0.68 +/- 0.07; p less than 0.00005. Both right ventricular end-systolic and end-diastolic volumes were greater than left ventricular end-systolic and end-diastolic volumes. This resulted in decreased right ventricular ejection fraction compared to left ventricular ejection fraction. The difference between the two ventricles may be due to compliance, muscle mass, and anatomic configuration with a net result of one chamber more completely emptying than the other. Thus it appears that the relationships between right and left ventricular volumes noted in infancy and childhood persist in adult life.     

Echocardiographic and anatomic evaluation of left ventricular thrombosis

The aim of this study was to assess the correspondence between two-dimensional echocardiographic (2D-Echo) and anatomic features of left ventricular thrombi (LVT), with particular reference to LVT shape and dimensions. The study population was composed of 23 patients who were admitted to our intensive cardiac care unit with an anterior acute myocardial infarction and who died during the hospitalization. Every patient underwent serial echocardiographic examinations, the last one performed within the 24 hours preceding death. The diagnosis of LVT required the agreement of three independent observers. Doubtful cases were considered as negative. With regard to shape, the LVT were defined as mural or protruding. Two measures of the LVT were obtained in each case: the longest dimension and the greatest one perpendicular to the initial dimension. At post-mortem examination we obtained sections of the heart comparable with an echocardiographic four chamber view. LVT were detected by 2D-Echo in 12/23 cases. Post-mortem examination confirmed the presence of LVT in these 12 patients. A thin apical thrombotic layer, whose presence had been defined previously as doubtful, was observed in another patient. The sensitivity of 2D-Echo was 92% and the specificity 100%. At 2D-Echo, shape was mural in 2 patients and protruding in 10. Complete agreement was found between 2D-Echo and anatomic findings as far as the morphology of LVT is concerned. The 2D-Echo measurements of LVT showed a high correlation with autopsy (r = 0.95; r = 0.86); we conclude that 2D-Echo provides accurate evaluations of the shape and the dimensions of LVT.     

Echocardiographic diagnosis of left ventricular hypertrophy.

Echocardiograms were obtained on 27 adults with electrocardiographic criteria of left ventricular hypertrophy (LVH) to determine how echocardiograms might best identify LVH. Both the left ventricular (LV) posterior wall thickness and interventricular septal thickness were found by echocardiography to be increased (greater than or equal to 12 mm) in only 13 of 27 patients (48%) with LVH. The LV was dilated (greater than or equal to 58 mm) in the absence of posterior wall thickening in 9 of 27 patients (33%). The LV mass, estimated from standardly measured dimensions, was increased (greater than 200 g) in 21 of 27 patients (78%) and when measurements were made by the Penn method, mas was increased in all patients. These observations indicate that the echocardiographic estimation of LV mass is a more sensitive indicator of LVH than LV posterior wall and septal thickness. Since LVH is defined as an increased mass of LV muscle, these observations are consistent with this fundamental definition of left ventricular hypertrophy.     

Echocardiographic demonstration of decreased left ventricular dimensions and vigorous myocardial contraction during syncope induced by head-up tilt

Two-dimensional echocardiography was performed during a head-up tilt test in 11 control subjects (group I) and 18 patients with recurrent unexplained syncope. In four patients (group II), the head-up tilt test was negative at baseline and after isoproterenol infusion. Syncope was induced during baseline head-up tilt in nine patients (group III) and after isoproterenol challenge in five (group IV). The echocardiographic variables assessed were left ventricular end-systolic and end-diastolic areas and percent fractional shortening. At the end of head-up tilt, end-systolic area decreased by 4.5 +/- 1.3 and 3.0 +/- 1.2 cm2 in groups III and IV, respectively, compared with 0.5 +/- 0.7 and 0.2 +/- 0.1 cm2 in groups I and II, respectively (p less than 0.04). Similarly, end-diastolic area decreased by 5.5 +/- 2.6 cm2 in group III compared with 2.7 +/- 1.9 and 1.75 +/- 0.4 cm2 in group I and II, respectively (p less than 0.04). Additionally, at the end of the baseline study, fractional shortening was significantly greater in group III and group IV (43 +/- 5%) than in groups I and II (p less than 0.01). In conclusion, syncope induced by head-up tilt is associated with vigorous myocardial contraction and a significant decrease in left ventricular end-systolic dimensions. This left ventricular hypercontractility may play an important role in the pathogenesis of syncope induced by head-up tilt.     

Intracardiac ultrasound determination of left ventricular volumes: In vitro and in vivo validation

Objectives. This study was designed to assess the feasibility of calculating left ventricular volumes using intracardiac ultrasound.Background. Previous studies have validated transthoracic echocardiographic determinations of left ventricular volumes and have indicated the superiority of Simpson rule reconstruction algorithms. The feasibility of imaging the left ventricle with intracardiac ultrasound has also been demonstrated.Methods. The determination of left ventricular volumes with Simpson rule reconstruction of intracardiac ultrasound images was evaluated in two phases. In vitro validation was performed in 29 animal hearts preserved in either a nondistended or distended state. Latex cast volumes were the reference standard. In vivo studies used 14 pigs, and compared intracardiac ultrasound volumes and ejection fraction with single-plane contrast angiographic values. A 12.5-MHz device was used to record short-axis images at 0.5-cm intervals. These were used to reconstruct the ventricle as a stack of cylindric elements using all imaged levels as well as sections recorded every 1 and 2 cm and at a single midventricular level.Results. In the in vitro hearts, when all recorded sections were used, there was excellent agreement between intracardiac ultrasound and latex cast volumes (intracardiac ultrasound volume = 0.89 latex cast volume + 2.22, r = 0.95; intracardiac ultrasound volume = 0.97 latex cast volume + 0.91, r = 0.99) for nondistended and distended hearts, respectively. In vivo, there was again close correspondence between ultrasound and angiographic volumes (intracardiac ultrasound volume = 1.04 angiographic volume −3.6, r = 0.91). The relation between intracardiac ultrasound and angiographic ejection fraction was fair (intracardiac ultrasound ejection fraction = 1.00 angiographic ejection fraction + 6.85, r = 0.69). Excellent correlations for the volumes were maintained as the number of cross sections was reduced to those recorded every 1 and 2 cm (r = 0.87 to 0.99). With a single midventricular site more variable but generally good correlations were obtained (r = 0.77 to 0.99).Conclusions. The application of Simpson rule reconstruction to short-axis images of the left ventricle obtained with intracardiac ultrasound provides accurate determination of left ventricular volumes in animal hearts. This technique may prove useful in the analysis of left ventricular structure and function.