Intracardiac Flow Analysis of the Tetralogy of Fallot Registry of 4D Flow Energetics and Kinetics (TREK) Multicenter study

Presenting Author(s)

• 

  Yue-Hin Loke, MD

  Associate Professor
  Children's National Medical Center

Primary Author(s)

• 

  Yue-Hin Loke, MD

  Associate Professor
  Children's National Medical Center

Co-Author(s)

• JB

  Jose Maria Lorenzo Bunag

  Research Trainee
  Children's National Hospital
• RO

  Ryan P. O'Hara, PhD

  Postdoc
  Children's National Hospital
• MA

  Mithra Agamy, BSc

  Research Trainee
  Children's National Hospital
• JK

  Jared D. Klein, MD

  Assistant Professor of Pediatrics
  Joe DiMaggio Children's Hospital
• MD

  Matthew Dove, MD

  Pediatric Cardiologist
  Vanderbilt
• 

  Laura Olivieri, MD

  Associate Professor of Pediatrics
  Children's Hospital of Pittsburgh of UPMC
• 

  Rajesh Krishnamurthy, MD

  Professor
  The Ohio State University
• AC

  Adam B. Christopher, MD

  Assistant professor
  UPMC Children's Hospital of Pittsburgh
• PV

  Pavlos P Vlachos, PhD

  Professor
  Purdue University
• EB

  Elias Balaras, PhD

  Professor
  George Washington University
• FC

  Francesco Capuano, PhD

  Assistant Professor
  Universitat Politecnica deCatalunya Barcelona Tech, Spain

Background: Patients with repaired Tetralogy of Fallot (rTOF) develop chronic pulmonary regurgitation (PR) leading to ventricular dysfunction. These patients also develop complex intracardiac blood flow inefficiencies which can be measured by time resolved three-dimensional phase-contrast imaging (4D flow). In our study, we quantified regional distributions of kinetic energy (KE) of the great vessels and ventricles in rTOF patients, using a new multi-center 4D flow registry (Tetralogy of Fallot Registry of 4D Flow Energetics and Kinematics –TREK).

Methods: 4D flow datasets of rTOF patients from 5 centers (Table 1) were retrospectively collected and analyzed. Cardiac magnetic resonance datasets with any stent artifact were excluded. Clinical outcomes included exercise capacity (% predicted VO_2-max) as measured by most recent exercise stress test. 3D models of the pulmonary arteries (PA), aorta (Ao), right and left ventricles (RV/LV) were segmented using 3D Slicer. 4D flow was post-processed using ITFlow (Cardioflow, Japan - Fig 1). The average KE indexed to body surface area (mJ/m²) was measured in both systole and diastole. Normal controls were included for comparison. In rTOF, measurements were correlated against conventional CMR metrics and % predicted VO_2-max using the Pearson correlation coefficient.

Results: 4D flow datasets from 82 rTOF patients (24.4±12.7 years; 1.6±0.4 BSA) and 49 normal controls (15.1±4.8 years; 1.6±0.4 BSA) were analyzed. In systole, rTOF patients had increased average KE of the PA with concomitant decrease in average KE of the Ao, whereas in diastole there increased average KE of the PA, RV, and LV (Fig 2). Pulmonary regurgitant fraction correlated with average diastolic KE in the PA (r= 0.4479, p< 0.0001) and RV (r=0.5132, p< 0.0001). Finally, % predicted VO_2-max was correlated with increased average systolic KE in the Ao (r=0.4083, p=0.00054).

Conclusion: The preliminary results of this multicenter 4D flow study verify the alterations to intracardiac flow energetics previously reported in literature, in addition to identifying an association between reduction of KE in the Ao with decreased exercise capacity. The TREK study is ongoing to determine 4D flow biomarkers that establish the association between intracardiac flow and disease progression in rTOF patients.

Figure 1. 3D segmentation and 4D flow Post-Processing Strategy.