Abstract 13532: Comparison of Inferior Vena Cava and Subclavian Vein Collapsibility Index by Ultrasound for Determination of Relative Intravascular Volume in Acute Decompensated Heart Failure

Abstract

Introduction: Accurate assessment of relative intravascular volume is needed to guide management of acute decompensated heart failure (ADHF). Current assessments include history and physical examination (specific but not sensitive), and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) (sensitive but not specific).Ultrasound (US) of inferior vena cava (IVC) collapsibility with respiration is commonly used to assess intravascular volume and right atrial pressure (RAP) but may be technically challenging. US of subclavian vein (SCV) collapsibility may provide an alternative assessment. Hypothesis: In ADHF, SCV collapsibility index (CI) may correlate with IVC CI and RAP. Methods: Prospective study of non-ventilated patients with ADHF who had NT-proBNP within 24 hours of paired IVC and SCV diameter measurements by US. Results: Forty-two patients (median age 66.5 years, 45% female, and 64% white) were enrolled, with 52 encounters. Cardiovascular comorbidities included hypertension (93%), chronic kidney disease (64%), coronary artery disease (55%), atrial fibrillation/flutter (55%), and valvular disease (55%). Of 38 patients with known heart failure, 63% had HFrEF, 16% HFmrEF, and 21% HFpEF.Correlation of paired IVC CI and SCV CI with relaxed breathing was R = 0.65 (N = 36). Correlation of paired IVC CI and SCV CI with forced inhalation was R = 0.47 (N = 36). Log 10 NT-proBNP was inversely correlated with IVC CI (R = -0.35; N = 51) and SCV CI (R = -0.33; N = 36). For patients with right heart catheterization within 24 hours of US, correlation of RAP to IVC CI was R = -0.53 (N = 9), and RAP to SCV CI was R = -0.65 (N = 9). Moderate or severe tricuspid regurgitation decreased CI independently of intravascular volume and RAP (figure). Conclusions: US measurements of SCV CI correlate well with paired IVC CI in non-ventilated ADHF. RAP by RHC correlated better with SCV CI than with IVC CI. SCV CI may be a reliable alternative to IVC CI in assessing relative intravascular volume.