Pulmonary transit time measurement by contrast-enhanced ultrasound in left ventricular dyssynchrony.

Patrick Houthuizen,Hans C. van Assen,Salvatore Saporito,Harrie C. M. van den Bosch,Hendrikus H. M. Korsten,Ingeborg H. F. Herold,R. Arthur Bouwman,Anouk G. W. de Lepper,Massimo Mischi

doi:10.1530/erp-16-0011

Abstract

BackgroundPulmonary transit time (PTT) is an indirect measure of preload and left ventricular function, which can be estimated using the indicator dilution theory by contrast-enhanced ultrasound (CEUS). In this study, we first assessed the accuracy of PTT-CEUS by comparing it with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Secondly, we tested the hypothesis that PTT-CEUS correlates with the severity of heart failure, assessed by MRI and N-terminal pro-B-type natriuretic peptide (NT-proBNP).Methods and resultsTwenty patients referred to our hospital for cardiac resynchronization therapy (CRT) were enrolled. DCE-MRI, CEUS, and NT-proBNP measurements were performed within an hour. Mean transit time (MTT) was obtained by estimating the time evolution of indicator concentration within regions of interest drawn in the right and left ventricles in video loops of DCE-MRI and CEUS. PTT was estimated as the difference of the left and right ventricular MTT. Normalized PTT (nPTT) was obtained by multiplication of PTT with the heart rate. Mean PTT-CEUS was 10.5±2.4s and PTT-DCE-MRI was 10.4±2.0s (P=0.88). The correlations of PTT and nPTT by CEUS and DCE-MRI were strong; r=0.75 (P=0.0001) and r=0.76 (P=0.0001), respectively. Bland–Altman analysis revealed a bias of 0.1s for PTT. nPTT-CEUS correlated moderately with left ventricle volumes. The correlations for PTT-CEUS and nPTT-CEUS were moderate to strong with NT-proBNP; r=0.54 (P=0.022) and r=0.68 (P=0.002), respectively.Conclusions(n)PTT-CEUS showed strong agreement with that by DCE-MRI. Given the good correlation with NT-proBNP level, (n)PTT-CEUS may provide a novel, clinically feasible measure to quantify the severity of heart failure.Clinical Trial Registry: NCT01735838

Highlights

Intrathoracic transit time of blood flow can be used to estimate preload, blood volumes, and global ventricular function [1]
Pulmonary transit time (PTT), which is a component of intrathoracic transit time, might be suitable to quantify the severity of congestive heart failure, a disease characterized by increased circulation times and elevated filling pressures [3, 4, 5]
We investigated the agreement between the PTT measured by contrast-enhanced ultrasound (CEUS) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in a cohort of heart failure patients referred for cardiac resynchronization therapy (CRT)

Summary

Introduction

Intrathoracic transit time of blood flow can be used to estimate preload, blood volumes, and global ventricular function [1]. The relationship between the intrathoracic circulation time derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and different heart failure parameters has been confirmed [3, 4]. Pulmonary transit time (PTT), which is a component of intrathoracic transit time, might be suitable to quantify the severity of congestive heart failure, a disease characterized by increased circulation times and elevated filling pressures [3, 4, 5]. We hypothesized that PTT is a parameter related to the severity of congestive heart failure and correlates with MRI parameters of left ventricular dysfunction, echocardiographic estimates, and N-terminal pro-B-type natriuretic peptide (NT-proBNP)

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Discussion

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