In its classic definition, by FranÃ§ois-Louis Ganshof (1944), feudalism describes a set of reciprocal legal and military obligations among the warrior nobility revolving around the three key concepts of lords, vassals and fiefs.
The exact cause of intracardiac echogenic foci remains unclear; however, they appear to be caused by small deposits of calcium in the papillary muscle of the fetal heart.
Intracardiac echogenic foci are typically 1 to 4 millimeters in diameter, but can be as large as 18 millimeters. When observed sonographically, they are described as peas, bright reflectors, bright spots or golf balls, reflecting the fact that they appear as white as bone.