Right ventricular end-diastolic wall stress: does it impact on right atrial size, and does it differ in right ventricular pressure vs volume loading conditions?

BACKGROUND: Right ventricular (RV) diastolic dysfunction precedes RV systolic dysfunction. Improvement in noninvasive assessment of RV diastolic function may enable earlier detection of RV dysfunction, especially important in the assessment of patients with congenital heart disease. We investigated a new parameter we call RV end-diastolic wall stress (RVEDWS) in an effort to better characterize RV diastolic function.

METHODS: We retrospectively studied consecutive adults with right-sided congenital heart disease between January 2005 and November 2006. RVEDWS was calculated with the Laplace law: r × p/λ, where r = basal RV dimension at end-diastole, p = RV end-diastolic pressure obtained from catheterization of the right side of the heart, and λ = thickness of RV free wall at end-diastole in the subcostal view. Calculated RVEDWS was correlated to echocardiographically derived right atrial (RA) measurements by means of the Pearson correlation.

RESULTS: Twenty-four patients, aged 41 ± 15 years, were included in the study. Mean RVEDWS was 20 ± 11 g/cm(2) (range, 3-46 g/cm(2)). RVEDWS correlated significantly with RA area and volume (r = 0.71, P < 0.0001; r = 0.69, P < 0.001, respectively). An RVEDWS > 17 g/cm(2) had a sensitivity of 91% and specificity of 85% in predicting significant RA enlargement. RVEDWS was significantly higher in patients with RV volume overload compared with those with pressure or normal loading conditions (28 g/cm(2) vs 17 g/cm(2), P = 0.01).

CONCLUSIONS: RVEDWS correlates significantly with RA size and differs considerably between RV volume and pressure overload states. Further work is needed to determine whether this RV diastolic parameter can be predictive of clinical outcomes in patients with RV loading lesions.