Non-invasive evaluation of energy loss in the pulmonary arteries using 4D phase contrast MR measurement: a proof of concept

Abstract

BackgroundThe repair surgery of congenital heart disease (CHD) associated with the right ventricular (RV)-pulmonary artery (PA) pathophysiology often left patients with critical post-operative lesions, leading to regurgitation and obstruction in the PAs. These lesions need longitudinal (with time) assessment for monitoring the RV function, in order for patients to have appropriate treatment before irreversible RV dysfunction occurs. In this research, we computed energy loss in the branch PAs using blood flow and pressure drop data obtained from 4D phase contrast (PC) MRI, to non-invasively quantify the RV-PA pathophysiology.Methods4D PC MRI was acquired for a CHD patient with abnormal RV-PA physiology, including pulmonary regurgitation and PA stenosis, and a subject with normal RV-PA physiology. The blood velocity, flow rate, and pressure drop data, obtained from 4D PC MRI, were used to compute and compare the energy loss values between the patient and normal subjects.ResultsThe pressure drop in the branch PAs for the patient was −1.3 mmHg/s and −0.2 mmHg/s for the RPA and LPA, respectively, and was larger (one order of magnitude) than that for the control. Similarly, the total energy loss in the branch PAs for the patient, -96.9 mJ/s and −16.4 mJ/s, for the RPA and LPA, respectively, was larger than that for the control.ConclusionsThe amount of energy loss in the pulmonary blood flow for the patient was considerably larger than the normal subject due to PA regurgitation and PA stenosis. Thus, we believe that the status of RV-PA pathophysiology for CHD patients can be evaluated non-invasively using energy loss endpoint.

Ventricular kinetic energy may provide a novel noninvasive way to assess ventricular performance in patients with repaired tetralogy of Fallot

“…10,20,21 The development of 4D flow magnetic resonance imaging has provided a noninvasive method of collecting 4D velocity data needed to determine pressure, flow, and energy measurements throughout the cardiac cycle. 19 Noninvasive measurements of KE in the LV and RV were first described in prior studies utilizing 4D flow acquisitions and were thought to provide a nondirectional measure of the amount of work invested in overcoming the inertia of intracardiac blood during the cardiac cycle. 12,22 Although KE comprises only approximately 1% of the total LV work and 6% of total RV work at rest, 10,22 it plays a larger role in the myocardial work under exercise conditions than at rest.…”

Altered Right Ventricular Kinetic Energy Work Density and Viscous Energy Dissipation in Patients with Pulmonary Arterial Hypertension: A Pilot Study Using 4D Flow MRI

“…Lee et al studied the rates of pressure-flow and KE transferred between the branch PA and the MPA, as well as flow resistance due to MPA bifurcation, also relations derived from the Navier—Stokes equations. They showed that patients with congenital heart disease had considerably increased energy loss in the branch PAs compared to normal subject with normal PA physiology [ 36 ]. Besides energy loss, a modification in the 4D flow technique with asymmetrical 4-point motion encoding has allowed measurement of irreversible pressure loss through characterization of turbulent KE (34).…”

Aortic Dissection: Simulation Tools for Disease Management and Understanding

“…In order to analyse the reduction in flow resistance caused by the stenting operations, the kinetic energy loss (assuming negligible gravitational effect) in the system was analysed, similarly to the approach used by Lee et al (2013). The rate of kinetic energy loss (KE) at each boundary i at each time instance is given byK…”