Radial versus longitudinal myocardial deformation from gray-scale echocardiography

The objectives of this work are to evaluate a novel non-Doppler-based echocardiographic method that makes it possible to simultaneously obtain the radial and longitudinal components of myocardial velocity (V) and strain (S), and to assess whether left ventricular fiber architecture affects the net function of the myocardium. Previous reports state that differences in the estimation of regional function between septum and lateral walls can be related to the anatomic disposition of myocardial fibers. In this work we measure and compare in 21 healthy volunteers longitudinal and radial peak systolic velocity V (V(long), V(rad): cm/s), peak systolic strain S (S(long), S(rad): %) and time-to-peak S and V (T-Smax, T-V(max): ms) at the midsegments of the septal and lateral walls. Results show that V was higher, both in the radial and longitudinal components, in the lateral wall than in the septum (V(rad): 4.77 +/- 0.26 cm/s vs. 3.77 +/- 0.20 cm/s, p = 0.007; V(long): 5.60 +/- 0.48 cm/s vs. 4.13 +/- 0.11 cm/s, p = 0.01). Radial strain was higher in the septum (S(rad): 28.63 +/- 2.25% vs. 22.54 +/- 1.5%, p = 0.015), and longitudinal strain, in the lateral wall (S(long): -25.89 +/- 1.43% vs. -22.20 +/- 0.87%, p = 0.02). There was a significant delay in longitudinal T-Smax between the lateral and septal medial segments (mean: 14.5 ms; CI 95%: 0.3-28.6 ms; p = 0.04), with no difference in radial T-Smax (277.1 +/- 8.6 ms vs. 277.2 +/- 12.4 ms, p = 0.93). The assessment of regional myocardial function by this new method enables the simultaneous analysis of its radial and longitudinal components. These measurements correlate well with previous anatomical knowledge of the architecture of myocardial fibers, emphasizing its functional significance in regional myocardial function analysis.