Quantitative assessment of regional myocardial function at rest and during stress with Doppler tissue imaging (DTI) plays an important role in daily routine echocardiography. However, reliable visual analysis is largely dependent on image quality and adequate border delineation, which still remains a challenge in a significant number of patients. In this respect, an ultrasound contrast agent (UCA) is often used to improve visualization in patients with suboptimal image quality. The knowledge of how DTI measurements will be affected by UCA present in the tissue is therefore of significant importance for an accurate interpretation of local myocardial motion. The aim of this paper was to investigate how signal contribution from UCA and nonlinear wave propagation influence the performance of the autocorrelation phase shift estimator used for DTI applications. Our results are based on model experiments with a clinical 2-D grayscale scanner and computational simulations of the DTI velocity estimator for synthetically-derived pulses, simulated bubble echoes and experimentally-sampled RF data of transmitted pulses and backscattered contrast echoes. The results show that destruction of UCA present in the tissue will give rise to an apparent bidirectional velocity bias of individual velocity estimates, but that spatial averaging of individual velocity measurements within a region-of-interest will result in a negative bias (away from the transducer) of the estimated mean or mean peak velocity. The UCA destruction will also have a significant impact on the measured integrated mean velocity over time, i.e., displacement. To achieve improved visualization with UCA during DTI-examinations, we either recommend that it is performed at low acoustic powers, mechanical index
5.
Clinical usefulness of tissue Doppler imaging in patients with mild to moderate aortic stenosis: a substudy of the aortic stenosis progression observation measuring effects of rosuvastatin study.
Jassal, DS, Tam, JW, Dumesnil, JG, Giannoccaro, PJ, Jue, J, Pandey, AS, Joyner, CD, Teo, KK, Chan, KL
Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 2008;(9):1023-7
Abstract
OBJECTIVE Although impaired diastolic function is common in aortic stenosis (AS), little is known about the clinical usefulness of tissue Doppler imaging (TDI) to detect diastolic dysfunction in patients with mild to moderate AS. The objective was to describe both conventional and TDI measurements of diastolic function in asymptomatic patients enrolled in the Aortic Stenosis Progression Observation Measuring Effects of Rosuvastatin study, a multicenter study to assess the effect of rosuvastatin on the progression of AS. METHODS Baseline echocardiography measurements, including left ventricular interventricular septal thickness, posterior wall thickness, cavity dimensions, and ejection fraction were obtained. Conventional Doppler indices, including peak early (E) and late (A) transmitral velocities, E/A ratio, and E-wave deceleration time, were measured from spectral Doppler. Tissue Doppler measurements, including early (E') and late (A') velocities of the lateral annulus, were determined, and E/E' was calculated. RESULTS The study population included 172 patients (aged 57 +/- 13 years; 73 were female) divided into three categories of AS severity on the basis of peak velocity at baseline (group I: 2.5-3.0 m/s; group II: 3.1-3.5 m/s; group III; 3.6-4.0 m/s). Baseline hemodynamics, left ventricular dimensions, and conventional diastolic functional parameters were similar among all 3 groups. In patients with greater severity of AS, the lateral E' was lower and the E/E' (as an estimate of increased left ventricular end-diastolic pressure) was higher (P <.05). CONCLUSION In patients with mild to moderate asymptomatic AS, TDI measures of diastolic function are abnormal and related to the severity of AS. These findings may help to predict the future development of symptoms in this population.
6.
Isovolumic acceleration measured by tissue Doppler echocardiography is preload independent in healthy subjects.
Dalsgaard, M, Snyder, EM, Kjaergaard, J, Johnson, BD, Hassager, C, Oh, JK
Echocardiography (Mount Kisco, N.Y.). 2007;(6):572-9
Abstract
BACKGROUND Isovolumic acceleration (IVA) as assessed by Tissue Doppler Imaging (TDI) has been proposed as a measure of left ventricular (LV) contractility. IVA is believed to be less dependent on preload than previously proposed estimates. IVA has been measured at different locations, and studies have shown conflicting results. OBJECTIVES We investigated the impact of increased preload on modern echocardiographic estimates of contractility, including IVA performed at different locations, in healthy volunteers. METHODS Seventeen young healthy individuals (male 13, age 31(+/- 9) years) with no prior history of cardiovascular or metabolic diseases had a Doppler and Tissue Doppler echocardiographic study performed at baseline and after a rapid infusion of 30 ml/kg of bodyweight of isotonic saline. Results are given as mean +/- standard deviation (SD), differences tested by paired t-test. RESULTS Echocardiographic parameters used to determine changes in preload, altered significantly. E/e' increased both at the lateral (5 +/- 1 vs 7 +/- 1 P < 0.01) and at the septal side of the annulus (7 +/- 2 vs 9 +/- 2, P < 0.01). Afterload remained unchanged. IVA was unchanged regardless of the measurement location: in the basal free wall (1.21 +/- 0.58 vs 0.98 +/- 0.41, not significant (NS)) or in the mitral annulus (1.18 +/- 0.56 vs 1.15 +/- 0.33, NS). Peak systolic strain, measured at the basal segment of LV septum, increased significantly (15.4 +/- 5.0 vs 20.7 +/- 5, P < 0.05), while all other measurements for strain or strain rate (SR) remained unchanged. CONCLUSION IVA is unchanged following significant increases in preload in healthy subjects, and thus is a potentially useful measure of global LV contractility.
7.
Coronary flow reserve by contrast enhanced transesophageal coronary sinus Doppler measurements can evaluate diabetic microvascular dysfunction.
Nishino, M, Hoshida, S, Egami, Y, Kondo, I, Shutta, R, Yamaguchi, H, Tanaka, K, Tanouchi, J, Hori, M, Yamada, Y
Circulation journal : official journal of the Japanese Circulation Society. 2006;(11):1415-20
Abstract
BACKGROUND This study was undertaken to investigate whether coronary flow reserve (CFR) using coronary sinus flow (CSF), which can be measured by transesophageal Doppler echocardiography (TEDE), especially when contrast enhanced, is useful in evaluating microvascular dysfunction in patients with diabetes mellitus (DM). METHODS AND RESULTS CSF recordings using contrast enhanced TEDE were performed before and after adenosine triphosphate infusion (0.15 mg x kg(-1) x min(-1)) in 16 patients with type 2 DM and diabetic retinopathy and in 13 non-DM patients (control). Coronary angiography revealed normal epicardial coronary arteries. CFR was defined as the ratio of the antegrade flow velocity time integral in hyperemic conditions and basal levels. Clear envelopes of CSF were obtained in all DM patients using contrast-enhanced TEDE. CFR using CSF in the DM group was significantly decreased compared with the control group (1.4+/-0.4 vs 2.1+/-0.5, p<0.01), but there were no significant differences of age, ejection fraction, rate of hypertension and hypercholesterolemia between the 2 groups. Using 1.7 of CFR as the cut-off value, diabetic microvascular dysfunction could be detected with 82% sensitivity and 83% specificity. CONCLUSIONS CFR calculated by CSF using contrast-enhanced TEDE may be useful for evaluating diabetic microvascular dysfunction.
8.
Multicenter evaluation of SonoVue for improved endocardial border delineation.
Nanda, NC, Wistran, DC, Karlsberg, RP, Hack, TC, Smith, WB, Foley, DA, Picard, MH, Cotter, B
Echocardiography (Mount Kisco, N.Y.). 2002;(1):27-36
Abstract
OBJECTIVES Two multicenter studies were conducted to evaluate the safety and efficacy of SonoVue as a contrast agent for enhanced left ventricular endocardial border delineation (LVEBD), and to compare the efficacy of SonoVue and Albunex in adult patients with a suboptimal, nonenhanced echocardiogram. BACKGROUND The use of contrast to enhance echocardiographic assessment of LVEBD is well-established. SonoVue is a new microbubble contrast agent that contains sulfur hexafluoride. METHODS Patients were randomized to receive four injections of SonoVue (0.5, 1, 2, and 4 ml), or two injections of Albunex and two injections of hand-agitated saline (0.08 and 0.22 ml/kg). Echocardiographic images were evaluated at the study centers and by four blinded, offsite reviewers for degree of left ventricle opacification (LVO), duration of contrast enhancement, and LVEBD. RESULTS LVO scores were significantly higher for all doses of SonoVue. Patients with complete LVO ranged from 34%-87% for SonoVue and from 0%-16% for Albunex. The mean duration of useful contrast effect ranged from 0.8-4.1 minutes for SonoVue and < 15 seconds for Albunex. Mean increases in LVEBD scores ranged from 3.8-18.2 for SonoVue and 0.1-4.3 for Albunex. SonoVue (cumulative 7.5 ml dose) was well-tolerated, with a safety profile similar to that observed in the control group. CONCLUSIONS SonoVue is superior to Albunex for improving visualization of endocardial borders in patients with suboptimal noncontrast echocardiograms. Optimal increases in LVEBD, LVO, and duration of useful contrast effect were observed at the 2.0 ml dose of SonoVue.