Preload dependence of pulmonary haemodynamics and right ventricular performance

Systolic pulmonary artery pressure (SPAP) and right heart adaptation in relation to pre-existing preload are often disregarded. To determine volume-related changes in the pulmonary-right ventricle (RV) unit and the preload dependence of its components, we analysed pulmonary haemodynamics and right ventricular performance, taking advantage of the plasma volume removal associated to haemodialysis (HD).

Fifty-three stable patients on chronic HD with LVEF > 50% and without heart failure were recruited (mean age 63.0 ± 12.4 years; 31.2% women; hypertension in 89% and diabetes in 53%) and evaluated just before and after HD (mean ultrafiltration volume 2.4 ± 0.7 l). SPAP from both times were available in 39 patients. After HD, SPAP decreased (42.2 ± 12.6 to 33.7 ± 11.6 mmHg, p < 0.001) without modification of non-invasive pulmonary vascular resistance (1.75 ± 0.44 to 1.75 ± 0.40 eWU, p = 0.94). Age and drop in the E/e' ratio were the variables associated with greater reduction in PASP (p = 0.022 and p = 0.049, respectively). A significant reduction of right chamber sizes was observed, along with a diminution in measures of RV contractility, excluding RV longitudinal strain. Functional tricuspid regurgitation (FTR) diminution was observed in 26% of patients, occurring in every case with more than mild FTR. On multivariate analyses, left atrial size was the only predictor of pulmonary hypertension (defined as SPAP > 40 mmHg) (OR 1.29 (1.07-1.56), p = 0.006).

Rapid volemic changes may affect FTR grading, RV size and contractility, with RV longitudinal strain being less variable than conventional parameters. SPAP decreases after HD, and this reduction is related to age and greater diminution of the E/e' ratio.