Effect of Left Ventricular Systolic Pressure on Myocardial Strain Demonstrated by Transmural Myocardial Strain Profile

Utility of transmural myocardial strain profile for prediction of early left ventricular dysfunction in patients with Duchenne muscular dystrophy

Myocardial damage in Duchenne muscular dystrophy (DMD) has lethal outcomes, making early detection of myocardial changes in patients with DMD vital, because early treatment can help prevent the development of myocardial fibrosis. The aim of the present study was, therefore, to test the hypothesis that transmural strain profile (TMSP) analysis can predict future left ventricular (LV) dysfunction in patients with DMD with preserved ejection fraction. We studied 82 consecutive patients with DMD without LV wall motion abnormality, with an ejection fraction of 60 ± 5% (all ≥55%) and age 11 ± 3 years. Echocardiography was performed at baseline and 1 year of follow-up. TMSP in the posterior wall was evaluated from the mid-LV short-axis view. A normal TMSP pattern (1 peak in the endocardium, group 1) was seen in 44 patients, and TMSP with a notch (2 peaks in the endocardium, group 2) in the remaining 38 (46%). Wall motion abnormality in the posterior wall was observed in 16 patients (42%) in group 2 at 1 year of follow-up but in none of the patients in group 1 (42% vs 0%; p <0.001). Importantly, multivariate analysis showed that only TMSP with a notch (odds ratios 1.524, p <0.001) was an independent determinant of the presence of LV posterior wall motion abnormality at 1 year of follow-up. In conclusion, subclinical LV dysfunction can be detected by evaluation of TMSP in patients with DMD who do not have wall motion abnormalities by conventional echocardiography. TMSP with a notch proved effective for evaluating subtle early changes in patients with DMD and might be useful for predicting LV dysfunction.

A comparison of Doppler, tissue Doppler imaging, and strain rate imaging in the assessment of postexercise left ventricular function

Left ventricular (LV) function is characterized by contraction in the longitudinal, radial, and circumferential planes. Previous studies of postexercise changes in LV function have assessed global indices of LV function. The purpose of this study was to use 2-dimensional (2D) strain analysis to examine LV function following marathon running in the circumferential, radial, and longitudinal planes, and to compare these data with other global and regional indices of function. Fifteen (mean ± SD: age, 32 ± 7 years; stature, 1.76 ± 0.08 m; body mass, 77.8 ± 8.2 kg) competitors in the London Marathon were echocardiographically assessed pre- and postrace. 2D strain (ejection fraction (EF), Doppler (early (E) and late (A) trans-mitral filling), tissue Doppler imaging (TDI) (systolic (S′) and early diastolic (E′) wall-motion velocities); TDI-derived longitudinal strain (εTDI), and systolic and diastolic strain rate (SRTDI); and 2D-derived peak circumferential, radial, and longitudinal strain (ε2D), and systolic and diastolic strain rate (SR2D) were examined. Differences pre- and postrace completion were assessed using paired t tests, with alpha set at 0.01. All participants completed the marathon in a mean time of 213 ± 41 min. A varied response was observed for measures of LV systolic and diastolic function following completion of the marathon (mean ± SD): EF, 63 ± 6 vs. 63 ± 7% (p > 0.01); E:A, 1.70 ± 0.37 vs. 1.17 ± 0.37; E′:A′, 2.36 ± 0.79 vs. 1.60 ± 0.57 (p < 0.01); mean longitudinal εTDI, 19.1 ± 5.1 vs. 17.5 ± 4.2% (p < 0.01); mean longitudinal diastolic SRTDI, 1.81 ± 0.54 vs. 1.58 ± 0.51·s–1 (p < 0.01); mean longitudinal systolic SR2D, 0.73 ± 0.21 vs. 0.97 ± 0.22·s–1 (p < 0.01); mean longitudinal diastolic SR2D, 0.94 ± 0.34 vs. 1.01 ± 0.23·s–1 (p > 0.01); mean radial systolic SR2D, 1.20 ± 0.15 vs. 1.45 ± 0.32·s–1 (p < 0.01); mean radial diastolic SR2D, 1.19 ± 0.25 vs. 1.29 ± 0.41·s–1 (p > 0.01); mean circumferential systolic SR2D, –1.09 ± 0.16 vs. –1.24 ± 0.18·s–1 (p < 0.01); and mean circumferential diastolic SR2D, –1.27 ± 0.28 vs. –1.22 ± 0.31·s–1 (p > 0.01). Marathon running promotes a varied echocardiographic response, with some functional parameters showing no change, some increasing, and some decreasing postexercise. This varied response likely reflects the complexities of cardiac function and highlights the need to adopt a multimodality approach when assessing cardiac function following exercise.

Myocardial strain imaging for early detection of cardiac involvement in patients with Duchenne's progressive muscular dystrophy

OBJECTIVE

In patients with Duchenne's progressive muscular dystrophy (DMD), myocardial fibrosis begins from the epicardial half of the left ventricular posterior wall. Myocardial strain imaging by tissue Doppler echocardiography is a new method for assessing regional myocardial function. We hypothesized that this method might be useful for the early detection of subclinical myocardial involvement in DMD patients.

METHODS

Myocardial radial strain of the left ventricle was measured in 25 DMD patients (age: 14.8 +/- 3.1 years) with a normal left ventricular shortening fraction and 25 age-matched healthy controls.

RESULTS

Peak systolic radial strain of the posterior wall in a short-axis view of the left ventricle was significantly lower in DMD patients compared to control subjects (P < 0.0001). In the interventricular septum, peak systolic radial strain was not significantly different between the two groups. Receiver operating characteristic curve analysis differentiated DMD patients from control patients with 92% sensitivity and 92% specificity, when the cutoff value for systolic peak strain of the posterior wall was 61%. When radial strain was measured separately for the inner and outer halves of the posterior wall, a systolic negative strain was more frequently observed in the outer half than in the inner half of the posterior wall (6/25 vs. 0/25, P < 0.05).

CONCLUSIONS

Myocardial strain imaging in DMD patients was characterized by decreased peak systolic strain of the posterior wall despite normal standard echocardiographic findings. Strain measurement might be useful for early detection of subtle regional myocardial dysfunction.

Evaluation of transmural distribution of viable muscle by myocardial strain profile and dobutamine stress echocardiography

Transmural distribution of viable myocardium in the ischemic myocardium has not been quantified and fully elucidated. To address this issue, we evaluated transmural myocardial strain profile (TMSP) in dogs with myocardial infarction using a newly developed tissue strain imaging. TMSP was obtained from the posterior wall at the epicardial left ventricular short-axis view in 13 anesthetized open-chest dogs. After control measurements, the left circumflex coronary artery was occluded for 90 min to induce subendocardial infarction (SMI). Subsequently, latex microbeads (90 microm) were injected in the same artery to create transmural infarction (TMI). In each stage, measurements were done before and after dobutamine challenge (10 microg.kg(-1).min(-1) for 10 min) to estimate transmural myocardial viability. Strain in the subendocardium in the control stage increased by dobutamine (from 53.6 +/- 17.1 to 73.3 +/- 21.8%, P < 0.001), whereas that in SMI and TMI stages was almost zero at baseline and did not increase significantly by dobutamine [from 0.8 +/- 8.8 to 1.3 +/- 7.0%, P = not significant (NS) for SMI, from -3.9 +/- 5.6 to -1.9 +/- 6.0%, P = NS for TMI]. Strain in the subepicardium increased by dobutamine in the control stage (from 23.9 +/- 6.1 to 26.3 +/- 6.4%, P < 0.05) and in the SMI stage (from 12.4 +/- 7.3 to 27.1 +/- 8.8%, P < 0.005), whereas that in the TMI stage did not change (from -1.0 +/- 7.8 to -0.7 +/- 8.3%, P = NS). In SMI, the subendocardial contraction was lost, but the subepicardium showed a significant increase in contraction with dobutamine. However, in TMI, even the subepicardial increase was not seen. Assessment of transmural strain profile using tissue strain imaging was a new and useful method to estimate transmural distribution of the viable myocardium in myocardial infarction.