Masses Related to Fetal Heart
· Papillary muscles/chordae- These may sometimes be normally prominent and present as small discrete echogenic masses; they should not be confused with pathological tumors.
· Moderator band-The moderator band is normally placed within the apex of the RV. Occasionally this band is prominent and mimics a true mass.
· Eustachian valve- The valve of IVC (the eustachian valve) may be seen as a bright linear reflector, which is a normal anatomical structure.
· Chiari's network- Chiari’s network represents remnants of embryonic valves, visualized within the RA as echogenic linear reflectors. They are usually of no significance.
· Rhabdomyoma- This is the most common cardiac tumor occurring in the fetus. It is an intramural tumor but may protrude as a pedunculated echogenic mass into the cardiac lumen. They have been diagnosed as early as 16 weeks but are more usually seen at 24 weeks. Associated with tuberous sclerosis.
· Fibroma- These tumors lie within the cardiac wall but may present as echogenic pedunculated intracavitary masses. Arrythmias and sudden death are common.
· Hamartoma-This tumor has been reported as an intracavitary mass lesion in a newborn who presented with an arrhythmia.
· Hemangioma-An intra-atrial hemangioma has been identified retrospectively in a fetus, associated with hydrops.
· Rhabdomyoma- This is usually sessile and arises from the myocardium. The tumor is usually of the same echogenicity as normal myocardium but can be highly echogenic. Fetal arrythmias are common. Larger masses may obstruct blood flow. They may be associated with tuberous sclerosis.
· Fibromas- Fibromas are rare cardiac mass lesions. They may be solitary or multiple and may lie within the cardiac wall or be pedunculated, protruding into the cardiac cavity. The appearances may therefore be identical to rhabdomyomas.
· Brochogenic cyst- These lung/mediastinal masses/ may rarely occur within the myocardium and may even project into the ventricle or pericardial space. They have been reported in the newborn but not the fetus and do not usually cause hemodynamic disturbance.
· Mesothelioma of atriventricular node- This is an extremely rare intramural mass lesion which may present with cardiac arrhythmia.
· Teratina- Teratoma is the second most commonly occurring cardiac tumor in the fetus. It arises from the pericardium and may be cystic and pedunculated and may calcify. It is often associated with a pericardial effusion and may cause cardiac tamponade. Hydrops may also occur, particularly if masses obstruct the right ventricular inflow.
· Morgagni's hernia- Rarely the pericardium may be continuous with the peritoneum via the foramen of Morgagni. Bowel or liver may therefore herniate into the pericardium and mimic a teratoma.
· Pericardial cyst- The majority of these cysts are present at the right cardiophrenic angle, although some have been reported on the left. The cysts are usually attached to the pericardium, and vary in size from one to several centimeters. They are usually filled with clear fluid. Larger cysts may project into the anterior or posterior mediastinum.
· Teraroma- This is usually a pericardial tumor but may project into the peripericardial space. When cystic they may be indistinguishable from pericardial cysts. They may calcify and are associated with pericardial effusions, cardiac tamponade and fetal hydrops.