Geert Kleinnibbelink

Chapter 7 164 Invasive right ventricular (RV) pressure-volume loop provides the gold-standard to evaluate cardiac contractility, but also provides insight into cardiac function as increases in preload cause a rightward shift of the loop and elevates stroke volume (and vice versa ). Echocardiography has relevance in evaluating cardiac function but also in mechanics, specifically regarding the dynamic relationship between RV longitudinal strain and RV area; strain-area loop. 1 RV strain-area loop characteristics relate to afterload, whilst characteristics hold independent predictive capacity for morbidity/mortality in pulmonary arterial hypertension. 2, 3 Changes in preload alter cardiac dynamics that may induce shifts in the non-invasive RV strain-area loop (similar to shifts in RV pressure-area loops). To better understand the potential of RV strain-area loops in assessing RV function, we compared the impact of preload manipulation on RV strain-area loop versus pressure- area loop, and subsequently compared invasive and non-invasive assessment of cardiac contractility. We recruited 7 individuals (age 54±14 year, 71% female) undergoing right heart catheterisation (to diagnose pulmonary arterial hypertension). Participants provided informed consent prior to procedures. Study procedures were approved by local ethics committee (Radboudumc). During catheterisation a 24-mm AMPLATZER TM Sizing Balloon II (AGAMedical Corporation, Plymouth, USA) was introduced into the inferior vena cava for manipulation in preload. For direct time-point comparison between pressure, strain and area, we simultaneously recorded invasive RV pressure and 2D-echocardiographic images: 1) at baseline, 2) after intravenous infusionof 500ml saline (to increase preload), and 3) after intra-balloon inflation (to reduce preload). Echocardiographic data were analysed using QLAB V10.8 (Philips, Andover, USA) to measure RVLS and area (as previously described) 3, 4 , whilst RV pressure data were retrieved from Mac-Lab (GE Medical, Horton, Norway). After preload manipulation data were recorded within 1-minute after stabilization of the signal. Mean strain-area loops and characteristics across the time-points were compared using one-way ANOVA. The increase in preload caused a rightward shift of the pressure-area loop, whilst a decrease in preload caused a leftward shift and reduced stroke volume ( Figure 1 ). These characteristic shifts were also present in the strain-area loop, with an increase in preload inducing RV longitudinal strain decline and a decrease in preload causing an