Purpose or Case Report: Right ventricular (RV) function represents a prognostic marker in patients with congenital heart defects (CHD), essentially in patients with right bundle branch block (RBBB). Due to the limitations of echocardiographic ventricle volume assessment, cardiac magnetic resonance imaging (CMR) is nowadays the method of choice in the follow-up of these patients.
In a recently published study it has been shown that delayed RV contraction due to RBBB should be taken into account when performing CMR volumetric assessment with short axis plane method.
Since recent recommendations suggest axial plane volume measurements, therefore current work was designed to assess the impact of RBBB on cardiac volumetric parameters evaluated with the axial plane method.
Methods & Materials: 38 patients (aged 25.9±11.9 years) with Tetralogy of Fallot and RBBB were enrolled in this retrospective study. With post-processing CMR images RV end-systolic volume (ESV) and end-diastolic volume (EDV) were measured with axial plane method twice: once neglecting RBBB (group I) and once considering RBBB (group II). Consequently, RV stroke volume (SV) and RV ejection fraction (EF) were calculated separately for each group and then compared with each other. All of the measurements were obtained separately by two observers, one with many years, one with just a few experiences. Inter-observer agreement was also calculated regarding the RV volumetric data of all patients.
Results: A delayed RV contraction due to RBBB has been found. Therefore, RV-ESV of group I was 10.68%±5.08 higher compared to group II. Accordingly RV-SV and RV-EF were 19.1%±12.3 higher in group II. All of these differences were statistically significant (p<0.001). With considering RBBB EF shifted from reduced (<50%) to normal (≥50%) in 8% of the cases. A substantial intra-observer agreement (κ=0.68; 95% CI: 0.57-0.78) was found between the two observer regarding the right ventricle measurements.
Conclusions: Results confirm that delayed RV contraction due to RBBB should be also considered at CMR based volume measurements with axial plane method. Ignoring RV physiology in RBBB patients leads to underestimation of RV performance parameters respectively RV function.