ObjectiveTo assess left ventricular (LV) strain and displacement and their relations to LV geometry in patients with aortic stenosis (AS).DesignCross-sectional echocardiographic study in patients with AS. Peak circumferential, radial and longitudinal strain, and radial, longitudinal and transverse displacement were measured by 2D speckle tracking. Severity of AS was assessed from energy loss index (ELI). LV hypertrophy was present if LV mass/height2.7 ≥46.7/49.2 g/m2.7 in women/men and concentric LV geometry if relative wall thickness ≥0.43. LV geometry was assessed from LV mass/height2.7 and relative wall thickness in combination.SettingDepartment of Heart Disease, Haukeland University Hospital, Bergen, Norway.Patients70 patients with AS (mean age 73±10 years, 54% women).InterventionsNone.Main outcome measuresAssociation of regional and average LV myocardial strain and displacement with LV geometric pattern and degree of AS.ResultsAverage longitudinal strain was lower in the hypertrophy groups and correlated with higher LV mass index and relative wall thickness, lower stress-corrected mid-wall shortening and smaller ELI (all p<0.05). Average strain and displacement in other directions did not differ between geometric groups. In multivariate regression analysis, lower average longitudinal strain was associated with higher relative wall thickness (β=0.15), lower ejection fraction (β=−0.16), systolic blood pressure (β=−0.16) and energy loss index (β=−0.20) (all p<0.05) (R2=0.72). When relative wall thickness was replaced with LV mass, lower longitudinal strain was also associated with higher LV mass (β=0.21, p<0.05) (R2=0.73).ConclusionsIn patients with AS, lower average longitudinal strain is related to higher LV mass, concentric geometry and more severe AS.

Real-time elastography is a method for visualization of the elastic properties of soft tissue and may potentially enable differentiation between malignant and benign pathologic lesions. Our aim was to validate the method on a tissue-mimicking (TM) phantom and to evaluate the influence of different scanning parameters and investigator variability. A TM-phantom containing eight spherical inclusions with known storage modulus was examined using two different transducers on an ultrasound (US) scanner equipped with software for real-time elasticity imaging. The ultrasound transducers were moved vertically in a repetitive manner to induce strain. Two investigators performed series of standardized elastography scans applying a 0-4 categorical quality scale to evaluate the influence of seven parameters: dynamic range of elasticity, region-of-interest, frequency of transducer movement, rejection of elastogram noise, frame rate, persistence and smoothing. Subsequently, repeated examinations of four selected inclusions were performed using a visual analog scale (VAS) where investigators marked a 100 mm horizontal line representing the span in image quality based on experience from the first examination. The hardest and softest inclusions were imaged more clearly than the inclusions with elasticity more similar to the background material. Intraobserver agreement on elastogram quality was good (kappa: 0.67 - 0.75) and interobserver agreement average (kappa: 0.55 - 0.56) when using the categorical scale. The subsequent VAS evaluation gave intraclass-correlation coefficients for the two observers of 0.98 and 0.93, respectively, and an interclass-correlation coefficient of 0.93. Real-time elastography adequately visualized isoechoic inclusions with different elastic properties in a TM-phantom with acceptable intra- and interobserver agreement. Dynamic range of elasticity was the parameter with most impact on the elastographic visualization of inclusions.

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Mapping of blood velocities across the lumen of the ascending aorta was performed in eight patients during open-heart surgery. A Doppler ultrasound probe was constructed to measure velocities in 2 mm steps from the maximum convexity to the maximum concavity of aorta, 6 to 7 cm above the aortic valve. In five patients with angina and normal aortic valves, velocity profiles were very similar and showed the following main features: a skewed peak systolic velocity profile with the highest velocity along the left posterior wall, a bidirectional velocity profile in late systole and early diastole with retrograde velocities along the left posterior wall, and a sustained antegrade flow along the convexity well into diastole. The resultant mean velocity profile had the highest velocity at the convex side and a central minimum velocity. In patients with Medtronic-Hall tilting disc prostheses, where the larger opening was oriented backwards and to the right, mean flow velocity profile was skewed in the opposite direction of normal. Moreover, instant systolic velocity profiles were much more irregular and dependent on the exact orientation of the prosthesis. In one patient with aortic valvular disease, very irregular and different velocity profiles were found. Based on a symmetry assumption, overall mean velocity for the total cross section was computed, and the magnitude of error in estimation of total flow from measurement of velocities at different depths was calculated. Whereas aortic velocity profiles commonly refer to the systolic propulsion of blood, less is known about diastolic events in the ascending aorta. That mean diastolic flow in the ascending aorta is low compared with systolic flow does not preclude an important effect of diastolic velocities on the time-integrated or mean velocity profile. The scarce reports on this subject8 10 concluded that mean velocity profile in the ascending aorta is relatively flat, until recent reports from Vielli and Jenni and their co-workers12 13 showed that timeintegrated velocity varied considerably across the lumen of the ascending aorta.Current knowledge of this subject stems from computational models," 2 in vitro preparations,1 6 intraluminal and transluminal registrations in animals,7'-or noninvasive estimates in patients.

The aims of this study were to investigate gastric antral geometry and stress-strain properties by using transabdominal ultrasound scanning during volume-controlled distensions in the human gastric antrum. Seven healthy volunteers underwent stepwise inflation of a bag located in the antrum with volumes up to 60 ml. The stretch ratio and Cauchy stress and strain were calculated from measurements of pressure, diameter, and wall thickness. A second distension series was conducted in three volunteers during administration of the anticholinergic drug butylscopolamine. Analysis of stretch ratios demonstrated positive strain in the circumferential direction, negative strain in the radial direction, and no strain in the longitudinal direction. The stress-strain relation was exponential and did not differ without or with the administration of butylscopolamine. The wall stress was decomposed into its active and passive components. The well-known length-tension diagram from in vitro studies of smooth muscle strips was reproduced. The maximum active tension appeared at a volume of 50 ml, corresponding to a stretch ratio of 1.5. We conclude that the method provides measures of antral biomechanical wall properties and can be used to reproduce the muscle length-tension diagram in humans.