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Evaluation of Myocardial Motion in Patients with Fontan Circulation by Using Tissue Phase Mapping Cardiac Magnetic Resonance
Xue-Jhe Lu1, Meng-Chu Chang1, Ming-Ting Wu2,3, Ken-Pen Weng4,5, and Hsu-Hsia Peng1

1Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan, 2Department of Radiology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, 3Faculty of Medicine & Institute of Clinical Medicine, National Yang Ming University, Taipei, Taiwan, 4Department of Pediatrics, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, 5Department of Pediatrics, National Yang-Ming University, Taipei, Taiwan

Synopsis

Patients with Fontan circulation nowadays have a well long-term survival with the improvement of post-surgery care and follow-up examination techniques. However, ventricular dysfunction and heart failure may occur in a couple years after surgery. To evaluate the risk of cardiac events in an early disease stage is important for patient managements. In this study, we measured myocardial motion velocity by tissue phase mapping. Fontan patients presented significantly decreased systolic and diastolic longitudinal velocity. In conclusion, evaluation of myocardial motion velocity could provide helpful information in detecting myocardial remodeling of functional ventricle in Fontan patients.

Introduction

Fontan procedure is a palliation for patients who have congenital heart diseases that lead to single functional ventricle. For patients have completed Fontan procedure, the symptoms of ventricular dysfunction have been reported1. The risk of heart failure can elevate in a couple of years after surgery2. Despite global ejection fraction was established as a predictor of ventricular function, the regional ventricular deformation was also able to provide helpful information in depicting cardiac events in patients with heart failure3. Speckle tracking echocardiography and MRI-based feature tracking were used to evaluate the myocardial function by measuring myocardial strain4,5. However, the limited acoustic windows in echocardiography and indirect measurements of strain in feature tracking can limit their usefulness. Tissue phase mapping (TPM) cardiac magnetic resonance, encoding myocardial motion velocity directly from the phase images by phase-contrast MRI, has been used in a variety of cardiac diseases6,7. The purpose of this preliminary research is to investigate the feasibility of TPM to quantify the altered myocardial motion velocity in the functional ventricle of patients with Fontan circulation.

Method

The study population recruited 6 Fontan patients (age: 15.8±4.7 y/o, 4 males, 2 females) and 11 normal volunteers (age: 21.9±1.6 y/o, 8 males, 4 females). The TPM data was acquired in a 3 Tesla MR scanner (Tim Trio or Skyra, Siemens, Erlangen, Germany) using the 12-channel-cardiac arrayed coil with prospective ECG trigging, sampling 90% of cardiac cycle and navigator-guided free-breathing technique. The images were acquired in a short-axis view at base, mid, and apex with parameters of TR/TE=6.6/4.4 ms, flip angle=7∘, voxel size= 1.37 × 1.37 × 6 mm3, and Venc=15 cm/s in-plane and 25 cm/s through-plane. The scanning time of one slice is around 2 min, depending on subject’s cardiac rate and respiratory rate. The regions-of-interest (ROIs) on basal, mid, and apical planes were manually determined on magnitude images and were applied to phase images for calculation of wall motion velocity (Figure 1). The ROIs of three planes in the left ventricle were divided into 16 segments as recommend by America Heart Association (AHA) with a home-developing program. The peak systolic and diastolic velocity in radial (Vr) and longitudinal (Vz) directions were evaluated. Two-sample Mann Whitney U test were employed and p < 0.05 was considered statistical significance.

Result

Figure 2 shows the segmental systolic and diastolic Vr and Vz in bull’s eye plots in normal and Fontan groups. Compared to normal group, Fontan group presented lower diastolic Vr only in the lateral segment at apex (p < 0.05). Fontan patients exhibited significant lower Vz in almost all 16 segments both in systole and diastole (p < 0.05 ~ 0.001). In slice-wise comparison shown in Figure 3, Fontan group presented similar Vr with normal group. On the other hand, significant lower systolic and diastolic Vz were shown in Fontan group than normal group in basal, mid, and apical slices (all p < 0.01 ~ 0.001).

Discussion and Conclusions

In this study, we found significant lower systolic and diastolic Vz in Fontan group. Fontan circulation was reported to be associated with increased afterload8. The systolic myocardial motion velocities were proven to decrease with increased afterload in patients with aortic stenosis and hypertensive heart disease9. Therefore, the lower systolic and diastolic Vz shown in this study depicted the increased afterload and the ventricular dysfunction in patients with Fontan circulation. A previous study described that longitudinal deformation is more sensitive to the alteration in afterload10. In our study, Fontan group presented abnormal myocardial motion velocities only in Vz might describe that the altered ventricular function in our recruited patients was in a relatively early stage. In conclusion, evaluation of myocardial motion velocity could provide helpful information in detecting myocardial remodeling of functional ventricle in patients with Fontan circulation.

Acknowledgements

No acknowledgement found.

References

  1. Goldstein, Bryan H., et al. Relation of systemic venous return, pulmonary vascular resistance, and diastolic dysfunction to exercise capacity in patients with single ventricle receiving Fontan palliation. The American Journal of Cardiology. 2010;105(8):1169-1175.
  2. Khairy, Paul, et al. Long-term survival, modes of death, and predictors of mortality in patients with Fontan surgery. Circulation. 2008;117(1):85-92.
  3. Cho, Goo-Yeong, et al. Global 2-dimensional strain as a new prognosticator in patients with heart failure. Journal of the American College of Cardiology. 2009;54(7):618-624.
  4. Schmidt, Renate, et al. Value of Speckle‐tracking Echocardiography and MRI‐based Feature Tracking Analysis in Adult Patients after Fontan‐type Palliation. Congenital Heart Disease. 2014;9(5):397-406.
  5. Singh, Gautam K., et al. Accuracy and reproducibility of strain by speckle tracking in pediatric subjects with normal heart and single ventricular physiology: a two-dimensional speckle-tracking echocardiography and magnetic resonance imaging correlative study. Journal of the American Society of Echocardiography. 2010;23(11):1143-1152.
  6. Foell, D., et al. Hypertensive heart disease: MR tissue phase mapping reveals altered left ventricular rotation and regional myocardial long-axis velocities. European Radiology. 2013;23(2):339-347.
  7. Chang, Meng-Chu, et al. Left ventricular regional myocardial motion and twist function in repaired tetralogy of Fallot evaluated by magnetic resonance tissue phase mapping. European Radiology. 2018;28(1):104-114.
  8. Senzaki, Hideaki, et al. Ventricular afterload and ventricular work in Fontan circulation: comparison with normal two-ventricle circulation and single-ventricle circulation with Blalock-Taussig shunts. Circulation. 2002;105(24):2885-2892.
  9. von Knobelsdorff‐Brenkenhoff, Florian, et al. Myocardial dysfunction in patients with aortic stenosis and hypertensive heart disease assessed by MR tissue phase mapping. Journal of Magnetic Resonance Imaging. 2016;44(1):168-177.
  10. Donal, Erwan, et al. Influence of afterload on left ventricular radial and longitudinal systolic functions: a two-dimensional strain imaging study. European Journal of Echocardiography. 2009;10(8):914-921.
  11. Leitman, Marina, et al. Two-dimensional strain–a novel software for real-time quantitative echocardiographic assessment of myocardial function. Journal of the American Society of Echocardiography. 2004;17(10):1021-1029.

Figures

Figure 1. (Left column) The regions-of-interest (ROIs) on the magnitude images of basal plane in one normal control (21 years, Male) and one Fontan patient (14 years, Female) at peak systole and diastole. The pseudocolor-coded Vr (middle column) and Vz maps (right column) were also shown.

Figure 2. The bullseye plots of the peak systolic and diastolic Vr demonstrated similar values between normal and Fontan groups (a-d) . (e-h) Fontan group presented significantly lower peak systolic and diastolic Vz than normal. *p<0.05, **p<0.01, ***p<0.001.

Figure. 3. The peak systolic and diastolic Vr (a,b) and Vz (c,d) at base, mid, and apex in normal and Fontan groups. Fontan patients exhibited significantly lower systolic and diastolic Vz than normal controls. **p<0.01. ***p<0.001.

Proc. Intl. Soc. Mag. Reson. Med. 27 (2019)
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