Tricuspid lateral annular systolic velocity (S’ wave)
The systolic velocity of the tricuspid lateral annulus reflects the
longitudinal contraction of the RV [18]. S’ wave velocity is
obtained in the apical 4-chamber view by aligning the ultrasound beam
with the longitudinal excursion of the RV and by placing the tissue
Doppler marker on the lateral tricuspid annulus [18, 19]. Like
TAPSE, it is an easy obtainable parameter, but it is angle-dependent,
and it does not reflect the global systolic function of the RV [18,
19]. A S’ wave value < 9.5 cm/s reflects RV systolic
dysfunction [16, 18].
Studies found that decreased TDI systolic velocity of the tricuspid
annulus is an independent predictor of either cardiac death [25] or
of cardiovascular death and rehospitalizations for HF [26] in
patients with LV systolic dysfunction. Damy et al. showed that S’
wave<9.5 cm/s is a strong independent predictor of outcomes in
patients with LVEF<35%, while having superior prognostic
value when compared to other RV systolic parameters such as FAC and
TAPSE [27]. Similar results were found by de Groote et al. [28],
who found no prognostic value for TAPSE in patients with LV systolic
dysfunction but found that S’ wave<9.7 cm/s is an independent
predictor of cardiovascular death, with an enhanced prognostic value
when combined with RVEF measured by radionuclide angiography. Meluzin et
al. showed that the assessment of both TDI systolic and diastolic
velocities of the tricuspid annulus provide an enhanced risk
stratification in symptomatic HF with reduced EF. The authors found that
both TDI systolic and diastolic velocity were independent predictors of
survival and of event-free survival, and that patients with combined
peak systolic tricuspid annular velocity<10.8 cm/s and peak
early diastolic tricuspid annular velocity<8.9 cm/s had the
worst prognosis [29].