Carditis is the inflammation of the heart or its surroundings. The plural of carditis is carditides.
It is usually studied and treated by specifying it as:
Pericarditis is the inflammation of the pericardiumMyocarditis is the inflammation of the heart muscleEndocarditis is the inflammation of the endocardiumPancarditis is the inflammation of the entire heart: the epicardium, the myocardium and the endocardiumReflux carditis refers to a possible outcome of esophageal reflux (also known as GERD), and involves inflammation of the esophagus/stomach mucosa