A case of fetal ischemic cardiomyopathy diagnosed postnatally with cardiac magnetic resonance imaging (CMR)

Description of Clinical Presentation: A 30-week fetus with a history of hydrops at 16 weeks gestation, which had spontaneously resolved by 29 weeks, was seen in fetal cardiology clinic for suspected congenital heart disease. The fetal echocardiogram showed a hypertrophic and non-apex forming right ventricle (RV) and echo-bright segments in the interventricular septum. Tricuspid valve function was normal and there was antegrade flow across the pulmonary valve (PV) and ductus arteriosus. Given the appearance of the RV, pulmonary stenosis was suspected. The fetus delivered at 39 weeks and transitioned uneventfully. Transthoracic echocardiogram (TTE) showed a mildly hypoplastic and hypertrophic RV with mildly depressed systolic function, bidirectional flow across the atrial septum, but without evidence of pulmonary stenosis. By day of life three, the infant had weaned off supplemental oxygen with saturations in the low 90s and was discharged with close follow up and hope that RV compliance would improve with time. At 2 months old, the infant presented to the emergency department with fever and hypoxemia in the setting of rhinovirus infection. Repeat TTE showed a thin and akinetic RV free wall and suspected left ventricle (LV) aneurysm with moderately depressed biventricular systolic function. Origins and proximal courses of the coronary arteries were normal. CMR was performed for further function and tissue characterization.

Diagnostic Techniques and Their Most Important Findings: CMR was done on a 1.5T Siemens Magnetom Sola (Siemens Healthcare, Erlangen, Germany) scanner. A standard cardiomyopathy protocol was performed. ECG-gated free breathing balanced SSFP cines in standard views were performed for functional evaluation. To correct for breathing motion the number of signal averages was increased to four. Subsequently, free breathing motion-corrected late gadolinium enhancement (LGE) imaging (MOCO-PSIR) was obtained in standard views. The RV was moderately dilated with an ejection fraction of 17%. The entire RV free wall appeared very thin with only portions of the basal RV segments exhibiting contractility. The LV apical septal wall and apex were thinned and hypokinetic consistent with an LV aneurysm.

Learning Points from this Case: Based on LGE transmurality, and its correlation to the hypokinetic areas, along with the appearance of the RV on fetal echocardiogram, the diagnosis was most likely consistent with a fetal ischemic cardiomyopathy. In retrospect, the hydrops early in gestation was likely related (either causually or consequent to) ischemia. Unfortunately, the infant’s hemodynamic status precipitously declined, and the family elected for comfort care after receiving the CMR results.

Figure 1: (a) Fetal echocardiogram in the apical four chamber view in 2D showing a hypoplastic non-apex forming RV. (b) TTE on readmission showing an apical view of a mildly hypoplastic and hypertrophied RV with a thin and akinetic anterior apical wall and (c) a normal sized LV with thinning of the apical septal wall and apex consistent with a possible apical LV aneurysm(*). (d) PSAX showing normal PV and branch PAs.
Figure 2: ECG-gated SSFP short axis stack showing the moderately dilated RV (RV end diastolic volume 78ml/m2) with severely depressed function (ejection fraction 17%) and normal sized left ventricle (LV end diastolic volume 48ml/m2) with mildly depressed global systolic function (ejection fraction 45%).
Figure 3: (a) Free-breathing (MOCO-PSIR) short axis stack and (b) four-chamber showing extensive transmural late gadolinium enhancement involving the entire septal wall and right ventricular wall at the mid and apical ventricular segments corresponding with a hypokinetic LV apical aneurysm and akinetic portions of the RV wall.