Unraveling septal perfusion abnormalities in Ebstein's anomaly: A case report contrasting PET MPI with myocardial reality

Abstract

In Ebstein's anomaly, septal perfusion abnormality poses a challenge in traditional interpretations of myocardial blood flow. We report a single case of a 43-year-old female with known Ebstein's anomaly who was referred for preoperative cardiac evaluation prior to bariatric surgery. Due to her multiple cardiovascular risk factors and vague chest discomfort, positron emission tomography (PET) myocardial perfusion imaging (MPI) and cardiac magnetic resonance imaging (MRI) were performed. PET MPI demonstrated a partially reversible septal perfusion defect involving 30% of the left ventricular myocardium with fixed (12%) and ischemic (18%) components, while gated images revealed preserved wall motion. Cardiac MRI confirmed normal septal wall thickness and no myocardial fibrosis. These findings suggest that dyssynchronous atrial contraction and a shortened diastolic perfusion window associated with atrialization of the right ventricle are responsible for the observed perfusion abnormality rather than coronary artery disease or myocardial scar.

Keywords: Dyssynchronous atrial systole; Ebstein's anomaly; Myocardial perfusion imaging; PET MPI.

Fig. 1

PET myocardial perfusion images and corresponding polar map illustrating septal perfusion abnormality at rest, with larger perfusion abnormality at stress. (A) PET stress (top row) and rest (bottom row). (B) PET MPI polar maps with normal database comparison : stress (top row) and rest (bottom row).

Fig. 2

Quantitative myocardial blood flow (MBF) and myocardial flow reserve (MFR) measurements at rest and stress, illustrating relatively lower septal MBF compared to other LV territories at rest. Same relatively lower septal MBF pattern repeatedly seen during stress due to shortened diastolic perfusion. (A) Global and regional (3-vessel territory) MBF and MFR measurements at rest and stress. (B) Polar map (20-segment model) showing segmental MBF and MFR measurements. At rest (heart rate 75 bpm), septal segments show relatively lower MBF (0.6-1.0 mL/min/g) compared to other LV territories due to a shortened diastolic time. Under stress (heart rate 103 bpm), further diastolic shortening leads to reduced stress MBF in septal segments (1.4-1.8 mL/min/g) relative to other LV regions.

Fig. 3

Cardiac MRI imaging of Ebstein’s anomaly patient confirming no septal scar. (A) Static short-axis steady-state free precession (SSFP) MRI demonstrating normal septal thickness and morphology, without gadolinium enhancement. (B) Static SSFP 4-chamber view showing septal distortion characteristic of Ebsteins anomaly. (C) Late gadolinium enhancement (LGE) short-axis image demonstrates no enhancement, confirming the absence of fibrosis or scarring in the septum.

Fig. 4

Schematic diagrams illustrating septal perfusion dynamics at rest and stress in normal hearts versus those with Ebstein’s anomaly. (A) At rest in normal myocardium, coronary perfusion occurs during ventricular diastole, with atrial systole contributing to diastolic filling; septal perfusion is preserved. (B) Under stress in normal myocardium, increased heart rate shortens ventricular diastole, however coronary vasodilation maintains septal perfusion. (C) At rest in Ebstein’s anomaly, dyssynchronous contraction of the atrialized RV truncates the ventricular diastolic perfusion time; the overlap with dyssynchronous atrial systole further reduces the time available for septal perfusion, leading to diminished septal blood flow at rest. (D) Under stress in Ebstein’s anomaly, the increased heart rate further shortens diastole, exacerbating septal perfusion reduction, resulting in ischemia.