Cardiac myopathy is a medical condition related to

Concept: A compound medical term is read from its parts — a root that names the affected organ or tissue, and a suffix that names the kind of disorder. In a reading passage such a term is usually glossed by the writer in an appositive, the phrase introduced by "or" immediately after it. That gloss is the author's own definition, so the meaning is settled from the text itself and needs no outside knowledge.

Application: The passage introduces the term and defines it in the same sentence.

1. The opening sentence reads: "…fresh hope for patients of cardiac myopathy, or enlargement of the heart." The appositive "or enlargement of the heart" is the passage's own gloss of the term, and it names the organ outright.

2. The closing sentence points to the same place: the condition is "marked by an increase in the size of the heart's chambers and a decrease in the efficiency of pumping." Chambers and pumping efficiency are properties of the heart.

3. The causative factors listed in between — viral attack, parasite infection, long-term alcohol abuse, blood pressure, childbirth, family history — are all described as bringing on that same enlargement, so they add causes without shifting the site of the condition.

4. The terminology agrees: "myo-" denotes muscle and "-pathy" denotes disease, so the term names a disease of heart muscle. Clinically this is cardiomyopathy, defined by NHLBI and CDC as a disease of the heart muscle that reduces its ability to pump blood.

Cross-check: Nothing in the passage points to any other site.

• Vision is never mentioned; a disorder of the eyes would be described through the retina or the optic pathway, not through chamber size and pumping efficiency.

• Limb musculature is never mentioned; a disorder confined to the thigh and calf muscles would show as weakness or cramping while walking, not as an enlarged chamber.

• Coordination of posture and locomotion is never mentioned; a movement disorder would be described through tremor, rigidity or unsteadiness.

Result: Cardiac myopathy is a medical condition of the heart.