Intraventricular Pressure Difference Estimation based on Blood Speckle Tracking - Invasive Validation and Early Clinical Application.

Aims: Ventricular relaxation creates an intraventricular pressure difference (IVPD) and resultant diastolic suction. Non-invasive estimation by echocardiographic techniques would allow to clinically evaluate IVPD as an important component of diastolic functional assessment. The aims of the current study were to evaluate the accuracy of IVPD estimation based on Blood Speckle Tracking (BST) echocardiography compared to invasive pressure measurements and to clinically apply the method in children with univentricular hearts (UVH) and controls.

Methods and results: The 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 during early diastolic filling was performed in 83 healthy controls and 44 patients with UVH and compared between the groups.The validation in pigs included 103 measurements, demonstrating a mean difference of -0.01 mmHg (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 6 months-17.76 years, feasibility was 93.9 % in controls and 88.6% in UVH patients. Median IVPD was significantly higher in controls compared to UVH (-1.82 vs -0.88 mmHg, p < 0.001). Intraclass correlation coefficients for variability of clinical BST-data were 0.99 (interobserver) and 0.98 (intraobserver) respectively.

Conclusion: BST echocardiography provides accurate estimation of IVPD in early diastole. IVPD was significantly lower in children with UVH compared to controls suggesting lower diastolic suction which can impact overall filling dynamics.