Fetal echocardiography in cardiac tumors

Key points

Fetal cardiac tumors are extremely rare and most are benign.
They tend to appear between 20 and 30 weeks of pregnancy.
The most common types of fetal cardiac tumors are rhabdomyomas, teratomas, and fibromas respectively.
Fetal cardiac tumors may cause important complications, including arrhythmias, ventricular outflow or inflow obstruction, atrioventricular valve insufficiency, heart failure, and hydrops fetalis.
Cardiac tumors are generally easy to diagnose prenatally by fetal echocardiography.
Due to possible life-threatening complications, all cases should be referred to the perinatal center.
Pregnancy should be continued as long as possible if there are no significant cardiovascular complications.
The outcome of affected fetuses depends on the type of tumor and also on its location, size, number, cardiovascular complications, and associated extracardiac disorders.

Introduction

Fetal cardiac tumors are relatively rare, representing 0.02% to 0.13% of cases in fetal cardiac series. They tend to appear between 20 and 30 weeks of pregnancy . Most fetal cardiac tumors are benign, but they may cause important complications, including arrhythmias, ventricular outflow or inflow obstruction, atrioventricular valve insufficiency, heart failure, and hydrops fetalis . Rarely, interference with the coronary arterial circulation may cause sudden fetal death .

Heart tumors are generally easy to diagnose prenatally by fetal echocardiography. Due to possible life-threatening complications, all cases should be referred to the perinatal center .

Fetal primary cardiac tumors

Among the various histological types, the three most common types of fetal cardiac tumors are rhabdomyomas, teratomas, and fibromas, respectively . Most fetal primary cardiac tumors (FPCTs) are benign and fetal malignant and metastatic cardiac tumors are very rare .

Cardiac rhabdomyoma

Cardiac rhabdomyomas are the most common fetal cardiac tumors accounting for 70%–80% of cases in fetal cardiac series . Cardiac rhabdomyomas are benign tumors of striated muscle cells. Echocardiography shows a homogeneous, well-circumscribed mass that is significantly more echogenic relative to the myocardium .

Fig. 31.1, Fetal echocardiography at 26 weeks of gestation in 4-chamber (A) and short-axis view of ventricles (B) showing intracavitary rhabdomyomas (Supplementary Video 31.1).

Cardiac rhabdomyoma may be intracavitary or intramural, found within the ventricular free wall or septum, the apex, the outflow tract, the conus papillary muscles, or rarely, within the atria. They are multiple tumors in 90% of cases, with variable sizes, usually sessile but can occasionally be mobile .

Fig. 31.2, Left ventricular outflow tract (A) and right ventricular outflow tract (B) views of the same fetus as shown in Fig. 31.1 . Despite the presence of two large intracavitary tumors, there is no obstruction in the outflow tracts (Supplementary Video 31.2).

Cardiac rhabdomyoma may grow in size prior to 32 weeks and regress thereafter. Therefore serial assessment of an affected fetus is important particularly prior to 32 weeks . Symptoms depend on the size, number, and location of the rhabdomyomas. An intervention is only necessary when serious complications occur .

Fig. 31.3, Twenty-six weeks fetus with moderate tricuspid regurgitation due to large intracavitary rhabdomyoma in right ventricle. (A) Color Doppler and (B) pulsed Doppler flow of tricuspid regurgitation jet (Supplementary Video 31.3).

Despite the large size of tumors and flow obstruction or valve insufficiency, fetal hemodynamic compromise is rare in rhabdomyomas .

Fig. 31.4, Fetal echocardiography (four-chamber view) at 24 weeks, showing large rhabdomyoma of LV with mild pericardial effusion (A), the maximum diameter is approximately 46 mm (B). Several small tumors are also seen in RV free wall and right atrium (Supplementary Video 31.4).

Fig. 31.5, Multiple rhabdomyomas in 36 weeks fetus with arrhythmias (A) 4-chamber view (B) pericardial effusion (Supplementary Video 31.5).

Fetal outcome depends on the tumor size, impairment of flow, and rhythm disturbances. Early delivery at a viable age may be necessary for fetal hydrops with plans for neonatal intervention .

Fig. 31.6, Twenty-five weeks fetus with multiple rhabdomyomas. Four-chamber view shows a very large right atrial tumor without significant hemodynamic disturbance (Supplementary Video 31.6).

Rhabdomyomas are benign lesions and grow in utero due to the transmission of maternal estrogens to the fetus . In general, they tend to shrink after birth and an operation is rarely necessary .

Fig. 31.7, Early detection of cardiac rhabdomyomas in 20 weeks fetus. Four-chamber view (A) and basal short-axis view (B) show multiple small rhabdomyoma in LV and RV free wall, interventricular septum, and right atrium (Supplementary Video 31.7).

It should be noted that small tumors, when located in the septum or ventricular cavity, often mimic an echogenic focus, thus leading to difficulty in recognizing them through early ultrasonographic screening ( Supplementary Videos 31.1–31.7 ).

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