Velocity Transfer Function In The Right Pulmonary Artery And Impaired Cardiopulmonary Reserve In COPD

Abstract

Oleg F Sharifov,1 Thomas S Denney Jr,2 J Michael Wells,1,3,4 Gregory A Payne,1,4 Swati Gulati,1,3 Himanshu Gupta,5 Mark T Dransfield,1,3,4 Steven G Lloyd1,4 1Department of Medicine, University of Alabama at Birmingham (UAB), Birmingham, AL, USA; 2Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, USA; 3UAB Lung Health Center, Birmingham, AL, USA; 4Birmingham VA Medical Center, Birmingham, AL, USA; 5Advanced Cardiovascular Imaging, Valley Medical Group, Paramus, NJ, USACorrespondence: Steven G LloydDepartment of Medicine, University of Alabama at Birmingham, 1808 7th Avenue South, BDB 201, Birmingham, AL 35294-0012, USATel [phone]Fax [phone]Email [email protected] hypertension (PH) is an important prognostic indicator in patients with chronic obstructive pulmonary disease (COPD); however, PH in these patients is typically mild-to-moderate severity and invasive testing is not typically utilized.1 Though echocardiography can be used to screen for PH, it has limited accuracy in measuring pulmonary artery (PA) pressure and often hindered by window limitations in COPD patients.2 Cardiovascular magnetic resonance (CMR) does not have window limitations and can accurately evaluate the right ventricular (RV) and PA function. Therefore, there is a growing interest in the use of CMR for the diagnosis and management of PH, including patients with lung diseases. Recently, we have validated a novel non-invasive CMR-derived parameter that, similar to impedance, reflects pulsatile and resistive properties of the PA.3 This approach relies on the principle that compliant PA vessel walls cause changes in the velocity profile as it travels through the PA over the cardiac cycle. The frequency-dependent relationship between the input and output velocity profiles is described by a velocity transfer function (VTF), which is the relationship between the frequency spectra of input and output velocity.3 In suspected PH patients who underwent right heart catheterization, we found that VTF correlates with invasive PA impedance and the mean high-frequency modulus (MHFM) of VTF correlates with the pulmonary vascular resistance (PVR) and RV remodeling.3 Moreover, MHFM >1 accurately predicted an increased PVR.3 We hypothesized that elevated MHFM of VTF, reflecting increased PVR and pulmonary vascular disease, would be associated with reduced exercise capacity measured by 6-mins walk distance (6MWD) in a COPD cohort.

Keywords

• cardiac magnetic resonance imaging
• pulmonary hypertension
• 6 minute walk test