Intraventricular Pressure Difference by Blood Speckle Tracking - Invasive Validation and Clinical Application

BackgroundEarly diastolic relaxation creates an intraventricular pressure difference (IVPD) and resulting diastolic suction. Non-invasive estimation by echocardiographic techniques would allow to clinically evaluate this IVPD as an important component of ventricular filling. Recently, Blood Speckle Tracking (BST) echocardiography was introduced, allowing two-dimensional assessment of ventricular flow dynamics. Mitral inflow BST data can be used to estimate IVPD. The aims of the current study were to evaluate the accuracy of BST-based IVPD estimation compared to invasive pressure measurements in an in vivo animal model, and to clinically apply the method by comparing IVPD in children with univentricular hearts (UVH) and healthy controls. MethodsThe accuracy of BST-based IVPD-estimates was assessed in an open-chest porcine model, comparing BST-based IVPD with simultaneous repeated invasive pressure measurements in six pigs using micromanometer catheters. BST-based IVPD assessment was performed in 120 healthy controls and 44 patients with UVH < 18 years of age. Total IVPD (from base to apex) and apical IVPD (from the apical 2/3 of the ventricle) during early diastolic filling of the systemic ventricle was compared between patients with UVH and healthy controls. ResultsThe validation in pigs included 103 measurements, demonstrating a mean difference of - 0.01mmHg (p=0.33) and high correlation (r = 0.95, p-value < 0.001) between IVPD from BST (-1.31 {+/-} 0.28 mmHg) and invasive measurements (-1.30 {+/-} 0.31 mmHg). In the pediatric patients, age range 2 days-17.76 years, feasibility was 96% in controls and 88.6% in UVH patients. Total and apical IVPD were significantly higher in controls compared to UVH (-1.82 vs -0.88 mmHg and -0.63 vs -0.33 mmHg, p < 0.001). Variability was low with intraclass correlation coefficients of 0.99/0.96 (interobserver) and 0.98/0.99 (intraobserver) for total and apical IVPD respectively. ConclusionsBST echocardiography provides accurate estimation of early diastolic IVPD. When clinically applied in children, we found high feasibility and reproducibility. IVPD was significantly lower in children with UVH compared to controls suggesting lower diastolic suction which can impact overall filling dynamics. Clinical perspectiveO_ST_ABSWhat is newC_ST_ABSO_LIBlood speckle tracking echocardiography provides non-invasive estimation of intraventricular pressure difference in early diastole using two-dimensional blood flow velocities C_LIO_LIIntraventricular pressure difference based on blood speckle tracking is highly feasible, accurate and reproducible C_LIO_LIBlood speckle tracking demonstrates significantly reduced intraventricular pressure difference in early diastole in children with univentricular hearts indicating impaired relaxation and suction in these patients C_LI What are the clinical implicationsO_LIIntraventricular pressure difference based on blood speckle tracking is a novel and potential sensitive echocardiographic parameter to describe early diastolic ventricular relaxation and diastolic function in children with univentricular hearts C_LIO_LIBlood speckle tracking could improve assessment of diastolic function in children with congenital heart disease C_LIO_LINon-invasive estimation of intraventricular pressure difference based on blood speckle tracking could improve assessment of diastolic function both in children and adults with heart disease C_LI