Introduction The management of congenital patient’s frequently utilises cardiac magnetic resonance imaging to assess changes in patients cardiac function. Ventricular function assessment is challenging in this cohort due to complex ventricular geometry. Feature tracking uses routinely acquired MRI images to assess ventricular strain, a measure of cardiac contractility, which has been found in non-congenital cohorts to be a more sensitive marker of ventricular dysfunction than conventional imaging parameters.
We hypothesised that 1) patients with a systemic ventricle of right ventricular (RV) morphology would have impaired strain parameters compared to controls and 2) patients with a systemic RV in a single ventricle circulation would have more impaired contractility than those with a dual ventricular circulation.
Methods 3 groups were analysed: 1) 16 patients with hypoplastic left heart syndrome (HLHS) resulting in a single ventricle circulation (mean age 20±2 years; 81% male) 2) 16 patients with a systemic RV (sRV) in a dual ventricle circulation (age 32±5 years; 63% male) and 3) 16 healthy controls (mean age 30±4 years; 56% male). Participants underwent CMR at 1.5T for ventricular function assessment, analysis was undertaken using Circle cvi42 (v5.3) to calculate RV mid ventricular circumferential strain and peak longitudinal strain.
Results The two patient groups had increased RV volumes with reduced ejection fraction (EF), elevated RV mass, but similar stroke volumes compared to controls (Table 1).
The peak longitudinal RV strain was significantly reduced between the patient groups (HLHS mean −13±4; sRV −12±3) compared to controls (−18±5, p<0.001). However, there was no difference between the HLHS and sRV groups. Mid circumferential RV strain was not significantly different between both patient groups and also compared to controls (HLHS −13±4, sRV −12±4, controls −13±3, p 0.6). However comparison of mid circumferential RV strain to controls LV strain showed a significant reduction (controls LV mid circumferential strain mean −16±3, p 0.004) (Figure 1).
The peak longitudinal strain in patients correlated with the RV end diastolic volume index (r=0.38, p 0.03), RV end systolic volume index (r=0.52, p 0.002), RV EF (r=0.535, p?0.002) and RV mass index (r=0.43, p 0.01). The mid RV circumferential strain only correlated with RV EF (r=0.40, p 0.02) and no other remodelling parameters.
Discussion RV longitudinal strain was reduced in patients with a systemic RV irrespective of whether the ventricular configuration was single or dual. No difference was seen between the single circulation systemic RV compared to the dual circulation systemic RV, suggesting that RV remodelling is mostly in response to the systemic position rather than the ventricular configuration. Longitudinal studies will be required to assess the utility of the longitudinal strain in the prediction of outcomes in the follow up of these patients.
- Hypoplastic left heart
- Systemic right ventricle