Echocardiographic assessment of myocardial function and mechanics during veno-venous extracorporeal membrane oxygenation.

BACKGROUND: Transthoracic echocardiography (TTE) plays a fundamental role in the management of patients supported with extra-corporeal membrane oxygenation (ECMO). In light of fluctuating clinical states, serial monitoring of cardiac function is required. Formal quantification of ventricular parameters and myocardial mechanics offer benefit over qualitative assessment. The aim of this research was to compare unenhanced (UE) versus contrast-enhanced (CE) quantification of myocardial function and mechanics during ECMO in a validated ovine model. METHODS: Twenty-four sheep were commenced on peripheral veno-venous ECMO. Acute smoke-induced lung injury was induced in 21 sheep (3 controls). CE-TTE with Definity using Cadence Pulse Sequencing was performed. Two readers performed image analysis with TomTec Arena. End diastolic area (EDA, cm2), end systolic area (ESA, cm2), fractional area change (FAC, %), endocardial global circumferential strain (EGCS, %), myocardial global circumferential strain (MGCS, %), endocardial rotation (ER, degrees) and global radial strain (GRD, %) were evaluated for UE-TTE and CE-TTE. RESULTS: Full data sets are available in 22 sheep (92%). Mean CE EDA and ESA were significantly larger than in unenhanced images. Mean FAC was almost identical between the two techniques. There was no significant difference between UE and CE EGCS, MGCS and ER. There was significant difference in GRS between imaging techniques. Unenhanced inter-observer variability was from 0.48-0.70 but significantly improved to 0.71-0.89 for contrast imaging in all echocardiographic parameters. CONCLUSION: Semi-automated methods of myocardial function and mechanics using CE-TTE during ECMO was feasible and similar to UE-TTE for all parameters except ventricular areas and global radial strain. Addition of contrast significantly decreased inter-observer variability of all measurements.

Improving the echocardiographic assessment of pulmonary pressure using the tricuspid regurgitant signal-The "chin" vs the "beard".

AIM: Transthoracic echocardiography (TTE) is a fundamental investigation for the noninvasive assessment of pulmonary hemodynamics and right heart function. The aim of this study was to assess the correlation and agreement of Doppler calculation of right ventricular systolic pressure (RVSP) and pulmonary vascular resistance (PVR) using "chin" and "beard" measurements of tricuspid regurgitant velocity (TRVmax ), with invasive pulmonary artery systolic pressure (PASP) and PVR. METHODS: One hundred patients undergoing right heart catheterisation (RHC) and near simultaneous transthoracic echocardiography were studied. TRVmax was recorded for "chin" measurement (distinct peak TRVmax signal) and where available (63 patients), "beard" measurement (higher indistinct peak TRVmax signal). RESULTS: Measurable TRV signal was obtained in 96 patients. Mean RVSPchin 54.7 ± 22.7 mm Hg and RVSPbeard 68.6 = 23 ± 26.3 mm Hg (P < .001). There was strong correlation between both RVSPchin and RVSPbeard with invasive PASP (Pearson's r = .9, R2  = 0.82, P < .001 - r = .88, R = .78, P < .001, respectively.). Bland-Altman analysis for RVSPchin and RVSPbeard showed a mean bias of -0.5 mm Hg (95% limits of agreement -21.4 to 20.5 mm Hg) and -10.7 (95% LOA -35.5 to 14.2 mm Hg), respectively. Receiver operator characteristics of TRVmax "chin" and "beard" for diagnosis of pulmonary hypertension was assessed with optimal cut-offs being 2.8 m/s (sensitivity 93%, specificity 87%) and 3.2 m/s (sensitivity 91%, specificity 82%), respectively. There was similar correlation between PVRchin and PVRbeard (r = .87, R2  = 0.75, P < .001 and r = .86, R2  = 0.74, P < .001, respectively). At higher PVR, there was overestimation of calculated PVR using PVRbeard . CONCLUSION: The accuracy of noninvasive measurement of right heart pressures is increased using the "chin" in estimation of both RVSP and PVR.

Use of three-dimensional speckle-tracking echocardiography for quantitative assessment of global left ventricular function: a comparative study to three-dimensional echocardiography.

BACKGROUND: The aim of this study was to determine whether global strains derived from three-dimensional (3D) speckle-tracking echocardiography (STE) are as accurate as left ventricular (LV) ejection fraction (LVEF) obtained by two-dimensional (2D) and 3D echocardiography in the quantification of LV function. METHODS: Two-dimensional and 3D echocardiography and 2D and 3D STE were performed in 88 patients (LVEF range, 17%-79%). Two-dimensional and 3D global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain, and global area strain were quantified and correlated with LV function determined by 2D and 3D echocardiographic LVEF. Reproducibility, feasibility, and duration of study to perform 3D STE were assessed by independent, blinded observers. RESULTS: A total of 78 patients (89%) underwent 3D STE. All 3D speckle-tracking echocardiographic parameters had strong correlations with assessment of LV function determined by 2D and 3D echocardiographic LVEF. Three-dimensional GCS was the best marker of LV function (r = -0.89, P < .0001). Subgroup analysis demonstrated that 3D speckle-tracking echocardiographic parameters were particularly useful in identifying LV dysfunction (LVEF < 50%). Receiver operating characteristic curve analysis demonstrated areas under the curve of 0.97 for 3D GCS, 0.96 for 3D global radial strain, 0.95 for 3D global area strain, and 0.87 for 3D GLS. An optimal 3D GCS cutoff value of magnitude < -12% predicted LV dysfunction (LVEF obtained by 2D echocardiography < 50%) with 92% sensitivity and 90% specificity. There was good correlation between 2D GLS and 3D GLS (r = 0.85, P < .001; mean difference, -1.7 ± 6.5%). Good intraobserver, interobserver, and test-retest agreements were seen with 3D STE. Time for image acquisition to postprocessing analysis was significantly reduced with 3D STE (3.7 ± 1.0 minutes) compared with 2D STE (4.6 ± 1.5 min) (P < .05). CONCLUSIONS: Global strain by 3D STE is a promising novel alternative to quantitatively assess LV function. Three-dimensional STE is reproducible, feasible, and time efficient.

The role of Doppler left ventricular filling indexes and Doppler tissue echocardiography in the assessment of cardiac involvement in hereditary hemochromatosis.

Although cardiac dysfunction in hereditary hemochromatosis (HHC) can be evaluated by conventional echocardiography, findings are often not specific. To test the hypothesis that the assessment of (1) conventional Doppler left ventricular filling indexes and (2) intrinsic elastic properties of the myocardium by Doppler tissue echocardiography can both enhance the accuracy of echocardiographic diagnosis of cardiac involvement in HHC, a group of 18 patients with HHC (mean age 50 +/- 17 years) and 22 age-matched healthy subjects were studied. The following indexes were characteristic for HHC: (1) the duration of atrial reversal measured from pulmonary venous flow (ms) was longer (118 +/- 20 vs 90 +/- 16; P <.001); (2) systolic lateral mitral, early-diastolic medial mitral, and early-diastolic lateral tricuspid annular velocities were reduced by 23%, 31%, and 13%, respectively; (3) late-diastolic mean myocardial velocity and myocardial velocity gradient (MVG) were also reduced by 22% and 34%, respectively. Late-isovolumic relaxation (late-IVR) MVG (s(-1)) was positive in HHC as opposed to negative in healthy subjects (1.72 +/- 0.85 vs -0.89 +/- 1.15; P <.001) indicating impaired early-diastolic subepicardial relaxation in HHC. The assessment of atrial reversal flow duration, the difference in duration between A-wave and atrial reversal flow, and the presence of positive late IVR-MVG findings were the most accurate variables to differentiate patients with HHC from healthy subjects (80%, 67%, 94% sensitivity and 90%, 95%, 86% specificity, respectively).

Echocardiographic assessment of cardiac structure and function in rats.

BACKGROUND: Echocardiography is used in humans to characterise the structure and function of the heart, yet is relatively uncommon in studies on the rat, the most commonly used model of human cardiovascular disease. The aim of this study was to show that echocardiography in rats provides useful information on cardiac changes occurring in thyroid dysfunction and can also be used to characterise cardiac abnormalities. METHODS: Transthoracic echocardiography and Doppler techniques with high frequency, high frame rate imaging were used to define cardiac dimensions and function in 240 Wistar rats and cardiac abnormalities in Wistar and spontaneously hypertensive rats (SHR). RESULTS: Echocardiographic assessment of left ventricular dimensions and function and aortic flows was technically feasible in almost all adult Wistar rats and SHR, including those with thyroid dysfunction and cardiac abnormalities. Pulsed-wave Doppler profiles of mitral inflows to estimate diastolic function were less reliably obtained. CONCLUSIONS: Echocardiography is a powerful technique for non-invasive and serial determination of cardiac structure and function in rat models of human cardiovascular disease.