Correlation of right heart catheterization and duplex ultrasound to identify fistula volume flow

Arteriovenous fistula is the preferred form of hemodialysis access. Positive remodeling may result in high flow vascular access (HFVA), leading to elevated right heart pressures, cardiomyopathy and in advanced presentation-high-output heart failure (HOHF). Noninvasive duplex ultrasound (DUS) is the most commonly accepted mode of surveillance for HFVA. The reliability of DUS compared to the gold standard modality of right heart catheterization (RHC) to quantify access circuit volume flow (Qa) has not been reported. Our aim is to analyze a cohort of patients with suspected HOHF who underwent both studies and evaluate the concordance between Qa measurements.

We identified a consecutive cohort of eight patients with suspected HFVA and HOHF requiring diagnostic RHC. Qa was calculated by DUS and RHC. The association between the two measures was calculated using Pearson correlation, and agreement was assessed with Lin's concordance correlation coefficient. We evaluate the association between brachial artery (BA) diameter and the Qa agreement.

The mean Qa measured by DUS was 2623 ml/min, compared to a mean of 1538 ml/min measured by RHC. On average, the Qa measured by the DUS was 1086 ml/min greater than the RHC measurement, representing a 104% incremental difference. Only two of the eight cases (25%) had Qa measures within 500 ml/min. This discordance was greatest with a larger BA diameter, where a lower agreement measure of 0.39 and a moderate range correlation of 0.55 was found between Qa measured with RHC and DUS.

Although DUS is the most utilized modality to monitor Qa, low correlation is observed compared to RHC, discrepancy that is directly associated with BA diameter and may reflect true overestimation of Qa by DUS or result from measurements obtained under differing hemodynamic conditions (e.g. heart rate variability). RHC should be used more liberally for the diagnosis and management of HFVA, particularly when HOHF is suspected.