Luining, W. I. (Wietske) (2015) The effect of diffuse myocardial fibrosis in children with Tetralogy of Fallot on right and left ventricular function. thesis, Medicine.
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Abstract
Background Diffuse myocardial fibrosis (or scarring) of the heart muscle is associated with heart failure and ventricular dysfunction in many diseases. The aim of this study was to study the presence of myocardial fibrosis by T1 mapping CMR in pediatric patients with repaired Tetralogy of Fallot (TOF), and to correlate the degree of fibrosis with the extent of ventricular dysfunction. Furthermore, regional myocardial function of the right and left ventricle (RV and LV) was assessed with feature tracking (FT) CMR. Methods In 31 patients (mean age 13.9±2.4 years, 19 male) after surgical repair of TOF, T1 measurements were performed at the mid and basal ventricular levels in short axis (SA) in the entire LV, RV, interventricular septum (IVS) and free wall as well as in each LV segment separately. The extracellular volume (ECV) was calculated from native and post-contrast T1 times of myocardium, blood and the hematocrit. Global and segmental circumferential (LV), longitudinal (LV and RV) strain as well as the standard deviation of time to peak strain were measured using CMR FT software (TomTec, Germany). Sixteen asymptomatic children (mean age 13.4±2.6, 7 male) who had a CMR screening test for arrhythmogenic right ventricular cardiomyopathy were used as controls. Differences in ECV and cardiac contractility were compared between patients and controls with an unpaired t-test, as well as gender differences. The correlation of native T1 times and ECV with strain parameters was tested using Pearson’s coefficient. Native T1 times and ECV were correlated to exercise test results and surgical information. Results The mean pulmonary regurgitation (PR) fraction in TOF patients was 33.4±16.1% and RV end-diastolic and LV end-diastolic volumes were enlarged (RV EDV 148±40 ml/m2; LV EDV 91±12 ml/m2) with near-normal ejection fraction (RVEF 49.9±5%; LVEF 55.1±5.8%). Most native T1 times and ECV did not differ significantly between patients and controls. However, patients with a transannular patch repair and higher PR had higher ECV in some parts of the LV as compared to patients with a valve sparing or valved conduit surgery (e.g. ECV entire LV base 26.0±3.0 versus 22.8±2.7%). Also, longer bypass- and cross-clamp times at surgery were associated with higher native T1 times and ECV. In addition, patients of female gender had higher native T1 times and ECV as compared to males (i.e. ECV entire LV mid 25.2±2.9 versus 22.7±3.3, p<0.05). Some cardiomechanical values as measured with FT were lower in patients as compared to controls: the average of 6 segments in mid SA for circumferential strain (-21.51±3.79 versus -24.07±3.27, p<0.05) and circumferential strain rate (-1.31±0.29 versus -1.59±0.31, p<0.05) as well as some segmental values. LV ejection fraction correlated negatively with mid and basal SA circumferential strain averaged from 6 segments (r= -0.515, p<0.001 and r= -0.522, p<0.05), and with mid and basal SA circumferential strain rate averaged from 6 segments (r= -0.513, p<0.001 and r= -0.505, p<0.005). LV 4 chamber longitudinal strain, averaged from 6 segments, correlated with native T1 times in mid SA entire LV (r=0.511, p<0.05), mid IVS (r=0.546, p<0.05), basal IVS (r=0.495, p<0.05). Conclusion Our study revealed subtle increases in LV fibrosis in juvenile patients after TOF repair. Overall, however, the LV myocardium of adolescents appears remarkably healthy. Similarly, the abnormalities in myocardial strain and torsion in TOF were relatively modest. Our data reveal, however, that increased myocardial fibrosis can be associated with abnormal strain as a sign of adverse morphological and anatomical remodeling. The clinical consequences of these findings need to be examined in the future. Also, further work is necessary to substantiate the findings and to develop more sophisticated approaches to RV tissue characteristics.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Faculty supervisor: and Nieuwland, Dr. W. and Cardiologist Department of Cardiology University Medical Cen |
| Supervisor name: | Grosse-Wortmann, Dr. L. and Peadiatric Cardiologist Section head cardiovascular MRI Depa |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:43 |
| Last Modified: | 25 Jun 2020 10:43 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/436 |
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