A novel single-beat approach to assess right ventricular systolic function

Abstract

Clinical assessment of right ventricular (RV) contractility in diseases such as pulmonary arterial hypertension (PAH) has been hindered by the lack of a robust methodology. Here, a novel, clinically viable, single-beat method was developed to assess end-systolic elastance (E_es), a measure of right ventricular (RV) contractility. We hypothesized that this novel approach reduces uncertainty and interobserver variability in the estimation of the maximum isovolumic pressure (P_iso), the key step in single-beat methods. The new method was designed to include a larger portion of the RV pressure data and minimize subjective adjustments by the operator. Data were obtained from right heart catheterization of PAH patients in a multicenter prospective study ( data set 1) and a single-center retrospective study ( data set 2). To obtain P_iso, three independent observers used an established single-beat method (based on the first derivative of the pressure waveform) and the novel method (based on the second derivative). Interobserver variability analysis included paired t-test, one-way ANOVA, interclass correlation (ICC) analysis, and a modified Bland-Altman analysis. The P_iso values obtained from the two methods were linearly correlated for both data set 1 ( R² = 0.74) and data set 2 ( R² = 0.91). Compared with the established method, the novel method resulted in smaller interobserver variability ( P < 0.001), nonsignificant differences between observers, and a narrower confidence interval. By reducing uncertainty and interobserved variability, this novel approach may pave the way for more effective clinical management of PAH. NEW & NOTEWORTHY A novel methodology to assess right ventricular contractility from clinical data is demonstrated. This approach significantly reduces interobserver variability in the analysis of ventricular pressure data, as demonstrated in a relatively large population of subjects with pulmonary hypertension. This study may enable more accurate clinical monitoring of systolic function in subjects with pulmonary hypertension.

Keywords: end-systolic elastance; pulmonary arterial hypertension; right ventricle; single-beat method; ventricular contractility.

Fig. 1.

Illustration of the single-beat method for the calculation of E_es.

Fig. 2.

Illustration of the fitting range determination and interpolation using the first derivative approach (A) and second derivative method (B).

Fig. 3.

Example RV pressure trace, whose second derivative exhibited multiple minima. The same minima were selected by all 3 independent observers, as they resulted in the best interpolation of the isovolumic ranges.

Fig. 4.

Representative analysis of the RV pressure signal collected from a 55 yr-old male subject with PAH associated with systemic sclerosis, using the first derivative approach (A) and second derivative method (B).

Fig. 5.

Comparison of P_iso from the two methods, for data set 1 (A) and data set 2 (B). The error bars indicate the SD of the data obtained from different observers.

Fig. 6.

Results of the one-way ANOVA performed on data set 2 using the current (first derivative) and novel (second derivative) single-beat method. The analysis indicated significant interobserver differences for the first derivative method (observers F1–F3), in contrast to the second derivative method (observers S1–S3).

Fig. 7.

Interobserver agreement based on a modified Bland-Altman analysis of data set 2, for the current (first derivative; A) and novel (second derivative; B) single-beat method. The dashed lines indicate the limits of agreement with the mean (95% confidence intervals), which were narrower for the novel (second derivative) method.