David Dawson

Three-Dimensional Speckle Tracking of the Right Ventricle : Toward Optimal Quantification of Right Ventricular Dysfunction in Pulmonary Hypertension

BACKGROUND Quantitative assessment of right ventricular (RV) systolic function largely depends on right ventricular ejection fraction (RVEF). Three-dimensional speckle tracking (3D-ST) has been used extensively to quantify left ventricular function, but its value for RV assessment has not been established. OBJECTIVES This study sought to prospectively assess whether 3D-ST would be a reliable method for assessing RV systolic function and whether strain values were associated with survival. METHODS Comprehensive 2-dimensional echocardiographic assessment, 3D-ST of the RV free wall, and measurement of RVEF was performed in 97 consecutive patients with established pulmonary hypertension (PHT) (RVEF 31.4 ± 9.6%, right ventricular systolic pressure [RVSP] 76.5 ± 26.2 mm Hg) and 60 healthy volunteers (RVEF 43.8 ± 9.4%, RVSP 25.9 ± 4.3 mm Hg). RESULTS Area strain (AS) (-24.3 ± 7.3 vs. -30.8 ± 7.2; p < 0.001), radial strain (23.2 ± 14.4 vs. 34.9 ± 18.2; p < 0.001), longitudinal strain (LS) (-15.5 ± 3.8 vs. -17.9 ± 4.4; p = 0.001), and circumferential strain (CS) (-12.2 ± 4.5 vs. -15.7 ± 6.1; p < 0.001) were all reduced in patients with PHT, compared with normal individuals. AS and CS strongly correlated to RVEF (r = 0.851, r = -0.711; p < 0.001). Systolic dyssynchrony index was greater in PHT (0.14 ± 0.06 vs. 0.11 ± 0.07; p = 0.003) and correlated to RVEF (r = -0.563, p < 0.001). AS (hazard ratio [HR]: 3.49; 95% confidence interval [CI]: 1.21 to 7.07; p = 0.017), CS (HR: 4.17; 95% CI: 1.93 to 12.97; p < 0.001), LS (HR: 7.63; 95% CI: 1.76 to 10.27; p = 0.001), and RVEF (HR: 2.43; 95 CI: 1.00 to 5.92; p = 0.050) were significant determinants of all-cause mortality. Only AS (p = 0.029) and age (p = 0.087) were predictive of death after logistic regression analysis. CONCLUSIONS PHT patients have reduced RV strain patterns and more dyssynchronous ventricles compared with controls, which was relatable to clinical outcomes. AS best correlated with RVEF and provides prognostic information independent of other variables.

Assessment of left ventricular function by different speckle-tracking software

AIMS Two-dimensional (2D) speckle echocardiography enables objective assessment of left ventricular function through the analysis of myocardial strain, which can be measured by different speckle-tracking software. The aim of this study was to compare two different commercially available cardiac ultrasound systems and their manufacturer-specific speckle-tacking software for the quantification of global myocardial strain in a healthy population. METHODS AND RESULTS Twenty-eight healthy subjects (age: 38 +/- 12, 64% males) underwent two 2D echocardiograms within the same day using different cardiac ultrasound systems: Vivid 7 (GE Ultrasound, Horten, Norway) and Artida 4D (Toshiba Medical Systems). Standard apical and short-axis views of the left ventricle were obtained in each subject with a frame-rate range of 60 +/- 20 frames/s. Global longitudinal, radial, and circumferential strain values were analysed using their respective speckle-tracking software for Vivid (2D-strain EchoPac PC v.7.0.1, GE Healthcare, Horten, Norway) and Toshiba systems (2D Wall Motion Tracking, Toshiba Medical Systems). Global strain values were estimated from the average of regional left ventricular strain values. Agreement between the two systems and software was assessed by Bland-Altman method. Mean left ventricular ejection fraction was 59 +/- 7%. Global longitudinal, radial, and circumferential strain values were, respectively, -21.95 +/- 1.8, 46.97 +/- 5.5, and -23.18 +/- 3.3% when using 2D-strain EchoPac and -22.28 +/- 2.1, 40.74 +/- 4.3, and -27.17 +/- 4.7% when 2D Wall Motion Tracking was used (P = NS). Limits of agreement between both speckle-tracking software were narrower for global longitudinal strain (-2.25 to 3.65) than for radial and circumferential strain (-2.23 to 12.44 and -1.36 to 10.54, respectively). CONCLUSION Two commercially available speckle-tracking software appear to be comparable when quantifying left ventricular function in a healthy population. Global longitudinal strain is a more robust parameter than radial and circumferential strain for the assessment of myocardial function when different cardiac ultrasound systems are used for analysis.

Right ventricular remodelling in pulmonary arterial hypertension with three-dimensional echocardiography: comparison with cardiac magnetic resonance imaging.

AIMS Right ventricular (RV) mass and volume calculations are important correlates of survival in patients with pulmonary arterial hypertension (PAH). We tested the hypothesis that RV mass, volumes and function could be measured accurately with real-time three-dimensional echocardiography (3DE) in patients with PAH and compared those against cardiac magnetic resonance (CMR). METHODS AND RESULTS Sixty consecutive PAH patients and 20 normals were examined with 3DE and CMR. RV end-diastolic volumes (EDV), end-systolic (ESV), stroke volume (SV), ejection fraction (EF), and mass were measured in all patients and in normals. Two independent observers assessed variability using the Bland-Altman analysis agreement. RV volumes (in mL) and mass were similar between 3DE and CMR in PAH patients: [EDV (in mL) 183.2 +/- 38 vs. 187.3 +/- 41, P = 0.32; ESV (in mL) 122 +/- 33 vs. 126 +/- 36, P = 0.99; SV (in mL) 63 +/- 15 vs. 65 +/- 19, P = 0.06; EF (in %) 33 +/- 7 vs. 31 +/- 9, P = 0.16 and RV mass (g) 99 +/- 20 vs. 96 +/- 22, P = 0.42], respectively. Interobserver variability was similar between 3DE and CMR in PAH for all variables, with CMR showing less interobserver variability for EDV compared with 3DE in both patients and normals (patients: mean bias: CMR-EDV: 0.4 +/- 16 mL vs. 3DE-EDV: 6.9 +/- 17.9 and in normals: CMR-EDV: 0.1 +/- 9.8 vs. 3DE-EDV: 5.7 +/- 16.3, respectively), whereas EF and RV mass were poorly reproducible with no correlation between observers for 3DE and CMR. CONCLUSIONS RV remodelling in PAH patients can be accurately assessed with both 3DE and CMR. Both modalities are robust and reproducible with CMR being more reproducible for measurements of EF and RV mass.

Echocardiographic assessment of pulmonary hypertension: standard operating procedure

Patients with suspected pulmonary hypertension (PH) should be evaluated using a multimodality approach to ensure that they receive a correct diagnosis. The series of investigations required includes clinical evaluation, noninvasive imaging techniques and right heart catheterisation (considered to be the “gold standard” for the diagnosis of PH). Current guidelines recommend that a detailed echocardiographic assessment is performed in all patients with suspected PH. In this review we summarise a protocol adopted by the National Pulmonary Hypertension Centres of UK and Ireland and approved by the British Society of Echocardiography for the evaluation of these patients. The views and measurements described are recommended for diagnosis, assisting in prognosis and providing a noninvasive means of following disease progression or response to therapy.

Cardiac tissue velocities and strain rate in the early detection of myocardial dysfunction of asymptomatic boys with Duchenne’s muscular dystrophy: relationship to clinical outcome

Duchenne’s muscular dystrophy (DMD) is one of the most common neuromuscular disorders. Boys with DMD lose independent ambulation by the age of 12 and die of respiratory failure or cardiomyopathy in their late teens or early 20s.1 Histological changes in the heart include fibrosis, degeneration and fatty infiltration starting from the left ventricular posterior wall, which is a specific finding for DMD.2 The posterior wall can be more sensitive in identifying impaired myocardial function. Recent consensus guidelines on the early cardiac follow up and for the treatment of asymptomatic dysfunction have been proposed.3 An unresolved issue is, however, the timing of introducing treatment. Some authors have proposed that, in view of the almost invariable development of dilated cardiomyopathy (DCM), treatment should be started even in the absence of echocardiographic signs of dysfunction. It is therefore important to be able to identify early changes that precede DCM.3 We hypothesised that strain rate (SR) can identify early myocardial dysfunction in young asymptomatic boys with DMD without conventional echocardiographic signs of DCM. We related SR to the development of cardiomyopathy over a three-year follow up. Fifty six consecutive asymptomatic boys with DMD (mean age 8.8 (2.85) years) were enrolled. Diagnosis was confirmed by DNA analysis, unequivocal findings in muscle biopsy, or positive family history. The patients were not taking any cardiac drugs and had normal ECGs and routine echocardiograms (fractional shortening > 29%). Twenty two healthy volunteers (mean age 9 (SD 2.96) years) were recruited from the children’s outpatient department. We used the HDI 5000 (Phillips Medical Systems) machine equipped with a P4-2 transducer for conventional and tissue Doppler imaging echocardiographic studies. The conventional study included two dimensional and Doppler blood flow velocity measurements …

Morphologic and functional remodeling of the right ventricle in pulmonary hypertension by real time three dimensional echocardiography.

The aims of this study were to assess the right ventricle in different causes of pulmonary hypertension (PH) and to assess the changes of the tricuspid apparatus during this remodeling. The functional and morphologic changes of the right ventricle and the tricuspid apparatus in relation to different causes of PH remain elusive. A total of 141 consecutive patients were prospectively recruited, of whom 55 had pulmonary arterial hypertension (PAH), 32 had chronic thromboembolic disease (CTED), and 34 had PH secondary to mitral regurgitation (MR). Twenty age- and gender-matched healthy volunteers were also studied to serve as controls. Real-time 3-dimensional echocardiography was used to assess right ventricular (RV) volumes and tricuspid valve mobility. Overall, RV diastolic volumes were greater and RV ejection fractions lower in patients with PAH compared to those with CTED and MR (186.4 ± 48.8 vs 113.5 vs 109.4 ml, p < 0.001, and 33.2% vs 36.8% vs 66.8%, p < 0.001, respectively). Among the 3 PH groups, tricuspid valve mobility was most restricted in the CTED group and least restricted in the MR group. Tricuspid tenting volume was greater in the CTED and PAH groups than in the MR group (p < 0.01). Most patients with PAH (54.6%) had at least moderate tricuspid regurgitation, while in the CTED group, most (59.4%) had mild and only 37.5% had moderate tricuspid regurgitation (p < 0.01). Conversely, patients with MR (85%) had only mild tricuspid regurgitation. There was no correlation between RV systolic pressures and the RV ejection fraction or tenting volume. In conclusion, this study demonstrates that different causes of PH may lead to diverse RV remodeling, with the most adverse remodeling being in patients with PAH. In addition, changes of the tricuspid apparatus also differed, with the most adverse effects seen in patients with CTED.

Right ventricular function in patients with pulmonary hypertension; the value of myocardial performance index measured by tissue Doppler imaging

AIMS Myocardial performance index (MPI) measured by conventional Doppler is routinely used to assess right ventricular (RV) systolic function in patients with pulmonary hypertension (PH). Our aim was to determine whether MPI measured by Doppler tissue imaging (tMPI) is effective in assessing RV function in these patients. METHODS AND RESULTS Retrospectively, we have studied 196 patients with chronic PH [pulmonary arterial systolic pressure (PASP) 81 +/- 40 mmHg] and 37 healthy volunteers (PASP of 27 +/- 7 mmHg). According to the exclusion criteria, 172 patients were included in the final study cohort. All patients were evaluated for RV systolic function by different parameters. MPI was measured by both conventional and tissue Doppler imaging. Bland-Altman analysis showed moderate agreement between MPI and tMPI (the mean difference was -0.02, absolute difference = -0.32 to 0.29; 95% intervals of agreement, percentage of average = -46.6 to 40.8%). In 50 consecutive PH patients where additional parameters were calculated, we found a significant correlation between tMPI and RV ejection fraction (r = -0.73, P< 0.0001) and RV fractional area change (r = -0.58, P< 0.0001). No significant inter- and intra-observer variability was identified. CONCLUSION This study demonstrated a moderate agreement between two methods of measuring MPI. A good correlation of tMPI with RV ejection fraction and RV fractional area change was found indicating that tMPI might be superior to MPI Doppler. tMPI is a parameter unaffected by RV geometry and importantly has the advantage of simultaneously recording the time intervals from the same cardiac cycle.

The association between tricuspid regurgitation velocity and 5‐year survival in a North West London population of patients with sickle cell disease in the United Kingdom

Raised tricuspid regurgitant velocity (TRV) occurs in approximately 30% of adults with sickle cell disease (SCD), and has been shown to be an independent risk factor for death. TRV was assessed in 164 SCD patients who were subsequently followed up for survival. Raised pulmonary pressures were defined as a TRV jet ≥2·5 m/s on echocardiography. Elevated TRV was present in 29·1% of patients and it was associated with increased age and left atrial diameter. There were 15 deaths (9·1%) over a median of 68·1 months follow up; seven patients had increased TRV, and eight patients had a TRV<2·5 m/s. Higher TRV values were associated with a greater than 4‐fold increased risk of death (Hazard Ratio: 4·48, 99% confidence interval 1·01‐19·8), although we found a lower overall mortality rate than has been reported in previous studies. TRV was not an independent risk factor for death. We have confirmed the association between raised TRV and mortality in a UK SCD population whose disease severity appears to be less than that reported in previous studies. Further prospective studies are needed to more clearly characterize which patient factors modify survival in SCD patients with raised TRV.

Validation of the isovolumetric relaxation time for the estimation of pulmonary systolic arterial blood pressure in chronic pulmonary hypertension

AIMS Transthoracic echocardiography is a useful technique for non-invasive detection of pulmonary arterial systolic pressure (PASP). Isovolumic relaxation time (IVRT) measured by Doppler tissue imaging (DTI) is a sensitive measurement of changes in pulmonary vasculature. Our aim was to validate IVRT in the echocardiographic assessment of pulmonary hypertension (PH) patients. METHODS AND RESULTS We studied 196 PH patients (67% women, mean age 51.8 ± 16.6 years, mean PASP: 81 ± 24 mmHg) and 37 consecutive age- and sex-matched controls (58% women, mean age 44.7 ± 16.4 years, mean PASP 27.7 ± 5.5 mmHg). The estimation of PASP was derived from tricuspid regurgitation velocity according to the Bernoulli equation. The measurement of IVRT was calculated using pulsed tissue Doppler. In the PH group and in the healthy volunteers group (P < 0.0001), the average IVRT was 113.4 ± 28.5 ms [95% confidence interval (CI): 109-117] and 41 ± 12.5 ms (95% CI: 37-45), respectively. We found a strong correlation between IVRT and systolic pulmonary pressure in the PH group (r = 0.52, P < 0.0001) and a cut-off of 75 ms showed a sensitivity and specificity of 94% and 97%, respectively, for the prediction of elevated PASP. CONCLUSION The determination of IVRT by DTI is a simple and reproducible method that correlates well with PASP. It is, therefore, a parameter to consider in the echocardiographic assessment of patients with PH, and may be particularly important when the tricuspid Doppler signal is poor.

Early detection of subclinical left ventricular myocardial dysfunction in patients with chronic kidney disease

AIMS To identify subclinical left ventricular (LV) myocardial dysfunction using speckle tracking echocardiography (STE) in patients with chronic kidney disease (CKD), preserved LV ejection fraction (LVEF), and no cardiovascular history or symptoms. METHODS AND RESULTS Cross-sectional comparisons of conventional and STE parameters were performed between controls and patients with different stages of CKD. CKD patients were followed up for major adverse cardiovascular events (MACEs). We recruited 106 CKD patients and 38 controls. Mean age was 54.4 ± 15.1 and 36.9 ± 11.5 years, respectively (P < 0.001), with 49.1 vs. 52.6% being female (P = 0.705). There were 29 (27.4%) patients with CKD stages 1/2, 38 (35.8%) with stage 3, and 39 (36.8%) with stages 4/5. Global longitudinal strain (GLS) was more impaired when moving from controls to CKD stages 4/5 (-20.67 ± 3.06, -20.39 ± 2.29, -18.33 ± 3.81, -18.01 ± 2.64, controls vs. CKD stages 1/2, vs. CKD stage 3, vs. CKD stages 4/5, respectively, Padjusted = 0.016), whereas LV twist (16.2 ± 4.8, 18.51 ± 4.36, 19.91 ± 5.35, 24.6 ± 5.35, Padjusted < 0.001) and LV twist rate (101.7 ± 30.3, 110.4 ± 30.1, 121 ± 31.4, 154.8 ± 36.7, Padjusted < 0.001) increased. Risk factor-adjusted GLS (standardized beta β = -0.245, P = 0.025), strain rate (SR) [global longitudinal strain rates (GLSRs); β = -0.236, P = 0.019], and early diastolic longitudinal strain rate (GLSRe; β = 0.247, P = 0.019) were significantly associated with estimated glomerular filtration rate (eGFR), whereas LV twist (β = -0.432, P < 0.001), LV twist rate (β = -0.433, P < 0.001), and number of segments with diastolic dysfunction (β = -340, P < 0.001) were inversely and independently associated with eGFR. Impaired GLS (more than -16%) was observed in almost a quarter of CKD patients and associated with a reduced estimated MACE-free survival at 12-month follow-up (88.5 vs 93.7%, Plogrank = 0.038). CONCLUSION In CKD patients with no cardiovascular symptoms or history and preserved LVEF, STE can identify subclinical abnormalities of both systolic (decreased GLS and GLSR, increased LV twist, and twist rate) and diastolic (decreased GLSRe and increased number of segments with diastolic dysfunction) LV function.