Ultrasonic imaging of myocardial strain using cardiac elastography.

Clinical assessment of myocardial ischemia based on visually-assessed wall motion scoring from echocardiography is semiquantitative, operator dependent, and heavily weighted by operator experience and expertise. Cardiac motion estimation methods such as tissue Doppler imaging, used to assess myocardial muscle velocity, provides quantitative parameters such as the strain-rate and strain derived from Doppler velocity. However, tissue Doppler imaging does not differentiate between active contraction and simple rotation or translation of the heart wall, nor does it differentiate tethering (passively following) tissue from active contraction. In this paper, we present a strain imaging modality called cardiac elastography that provides two-dimensional strain information. A method for obtaining and displaying both directional and magnitude cardiac elastograms and displaying strain over the entire cross-section of the heart is described. Elastograms from a patient with coronary artery disease are compared with those from a healthy volunteer. Though observational, the differences suggest that cardiac elastography may be a useful tool for assessment of myocardial function. The method is two-dimensional, real time and avoids the disadvantage of observer-dependent judgment of myocardial contraction and relaxation estimated from conventional echocardiography.

Secundum atrial septal defect is a dynamic three-dimensional entity.

BACKGROUND: The aim of this study was to evaluate the diagnostic relevance of 3-dimensional (3D) echocardiography in the assessment of secundum atrial septum defect (ASD2). METHODS AND RESULTS: Twenty-three patients (age 2 to 58 years) with an ASD2 were studied by transthoracic (n = 9) or transesophageal (n = 14) echocardiography for the acquisition of a 3D data set before undergoing surgical repair. Qualitative (location, shape, and structure) and quantitative (largest and smallest anteroposterior and superoinferior diameters) characteristics were analyzed and compared with surgical findings. Intraobserver and interobserver variability were assessed. The gross anatomy of the ASD2, shown by the 3D images, was confirmed by the surgeon in 21 of 23 patients, but the presence of membranous or fenestrated remnants of the valvula foramina ovalis in the defect was not optimally visualized in 7 patients. Three-dimensional echocardiography revealed changes in diameter and shape of the ASD2 during the cardiac cycle. The measured largest and smallest anteroposterior diameters and their intraobserver and interobserver agreement were 274 +/- 12 mm, r = 0. 95 (P <.001), r = 0.92 (P <.001), and 194 +/- 9 mm, r = 0.96 (P <. 001), r = 0.94 (P <.001), respectively. The measured largest and smallest superoinferior diameter and their intraobserver and interobserver agreement were 304 +/- 26 mm, r = 0.90 (P <.001), r = 0.97 (P <.001), and 204 +/- 10 mm, r = 0.83 (P <.001), r = 0.84 ( P <.001), respectively. The correlation coefficient between 2D and 3D echocardiography for the largest anteroposterior and superoinferior diameter was r = 0.69 (P <.001) and r = 0.68 (P =.05), respectively. The correlation coefficient between the measurements from 3D reconstructions and direct surgical measurements was r = 0.20 (P = not significant) and r = 0.57 (P <.05), whereas between 2D and surgery was r = 0.50 (P <.05) and r = 0.26 (P = not significant). CONCLUSIONS: ASD2 has a complex morphology. Three-dimensional echocardiography provides better qualitative and quantitative information on its dynamic geometry, location, and extension as compared with standard 2D echocardiography and might be useful for device selection during catheter-based closure of ASD2.

Safety and utility of atropine addition during dobutamine stress echocardiography for the assessment of viable myocardium in patients with severe left ventricular dysfunction.

OBJECTIVE: To assess the feasibility safety and side effects of the addition of atropine to dobutamine stress echocardiography for the detection of viable myocardium in patients with left ventricular dysfunction (ejection fraction < or = 35%) prior to coronary revascularization. BACKGROUND: The assessment of viable and/or ischaemic myocardium has high prognostic value as regards improvement of function and survival after coronary revascularization. The addition of atropine to dobutamine during echocardiographic testing for the presence of viable myocardium is not common practice. Consequently, no data exist on the safety and additional diagnostic value of this practice. METHODS: Two hundred patients with left ventricular ejection fraction < or = 35% were studied. RESULTS: Test end-points were: target heart rate in 164 (82%) of the patients, severe angina in 18 (9%), maximum dobutamine-atropine dose in six (3%), severe ST segment changes in five (2%), cardiac arrhythmias in four (2%), and hypotension in three (1%). Viability could be assessed echocardiogaphically in 105/200 (53%) from a biphasic response (improvement of wall motion with low dose dobutamine and worsening with high dose), in 93 from ischaemia and in 12 from sustained or late improvements. In 36/105 (34%) patients, ischaemic myocardium could only be assessed after the addition of atropine. Cardiac arrhythmias occurred in 11/200 (6%) and hypotension (decrease of systolic blood pressure >30 mmHg) in 21/200 (11%). Neither the use of atropine nor the induction of ischaemia were associated with an increased incidence of cardiac arrhythmias or hypotension. CONCLUSIONS: In a large group of patients with severe left ventricular dysfunction, dobutamine stress echocardiography is feasible and safe in 186/200 (93%); the addition of atropine was necessary in 34% to assess myocardial viability. Hypotension and cardiac arrhythmias were the most frequent side effects, but were not related to the induction of ischaemia or addition of atropine.

Three-dimensional echocardiographic planimetry of maximal regurgitant orifice area in myxomatous mitral regurgitation: intraoperative comparison with proximal flow convergence.

OBJECTIVES: We sought to validate direct planimetry of mitral regurgitant orifice area from three-dimensional echocardiographic reconstructions. BACKGROUND: Regurgitant orifice area (ROA) is an important measure of the severity of mitral regurgitation (MR) that up to now has been calculated from hemodynamic data rather than measured directly. We hypothesized that improved spatial resolution of the mitral valve (MV) with three-dimensional (3D) echo might allow accurate planimetry of ROA. METHODS: We reconstructed the MV using 3D echo with 3 degrees rotational acquisitions (TomTec) using a transesophageal (TEE) multiplane probe in 15 patients undergoing MV repair (age 59 +/- 11 years). One observer reconstructed the prolapsing mitral leaflet in a left atrial plane parallel to the ROA and planimetered the two-dimensional (2D) projection of the maximal ROA. A second observer, blinded to the results of the first, calculated maximal ROA using the proximal convergence method defined as maximal flow rate (2pi(r2)va, where r is the radius of a color alias contour with velocity va) divided by regurgitant peak velocity (obtained by continuous wave [CW] Doppler) and corrected as necessary for proximal flow constraint. RESULTS: Maximal ROA was 0.79 +/- 0.39 (mean +/- SD) cm2 by 3D and 0.86 +/- 0.42 cm2 by proximal convergence (p = NS). Maximal ROA by 3D echo (y) was highly correlated with the corresponding flow measurement (x) (y = 0.87x + 0.03, r = 0.95, p < 0.001) with close agreement seen (AROA (y - x) = 0.07 +/- 0.12 cm2). CONCLUSIONS: 3D echo imaging of the MV allows direct visualization and planimetry of the ROA in patients with severe MR with good agreement to flow-based proximal convergence measurements.

Left ventricular ejection fraction in patients with normal and distorted left ventricular shape by three-dimensional echocardiographic methods: a comparison with radionuclide angiography.

BACKGROUND: Serial evaluation of left ventricular (LV) ejection fraction (EF) is important for the management and follow-up of cardiac patients. Our aim was to compare LVEF calculated from two three-dimensional echocardiographic (3DE) methods with multigated radionuclide angiography (RNA), in patients with normal and abnormally shaped ventricles. METHODS AND RESULTS: Forty-one consecutive patients referred for RNA underwent precordial rotational 3DE acquisition of 90 cut-planes. From the volumetric data set, LVEF was calculated by (a) Simpson's rule (3DS) through manual endocardial tracing of LV short-axis series at 3 mm slice distance and (b) apical biplane modified Simpson's method ( MS) in 29 patients by manual endocardial tracing of the apical four-chamber view and its computer-derived orthogonal view. Patients included three groups: A, 17 patients with LV segmental wall motion abnormalities; B, 13 patients with LV global hypokinesis; and C, 11 patients with normal LV wall motion. For all the 41 patients, there was excellent correlation, close limits of agreement, and nonsignificant difference between 3DS and RNA for LVEF calculation (r = 0.99, [-6.7, +6.9] and p = 0.9), respectively. For the 29 patients, excellent correlation and nonsignificant differences between LVEF calculated by both 3DS and BMS and values obtained by RNA were found (r = 0.99 and 0.97, p = 0.7 and p = 0.5, respectively). In addition, no significant difference existed between values of LVEF obtained from RNA, 3DS, and BMS by the analysis of variance (p = 0.6). The limits of agreement tended to be closer between 3DS and RNA (-6.8, +7.2) than between BMS and RNA (-8.3, +9.7). The intraobserver and inter-observer variability of RNA, 3DS, and BMS for calculating LVEF(%) were (0.8, 1.5), (1.3, 1.8), and (1.6, 2.6), respectively. There were closer limits of agreement between 3DS and RNA for LVEF calculation in A, B, and C patient subgroups [(-3.5, +5), (-8.4, +5.6), and (-7.8, +8.6)] than that between BMS and RNA [(-8.1, +10.7), (-11.9, +9.3), and (-9.1, +11.3)], respectively. CONCLUSIONS: No significant difference existed between RNA, 3DS, and BMS for LVEF calculation. 3DS has better correlation and closer limits of agreement than BMS with RNA for LVEF calculation, particularly in patients with segmental wall motion abnormalities and global hypokinesis. 3DS has a comparable observer variability with RNA. Therefore the use of 3DS for serial accurate LVEF calculation in cardiac patients is recommended.