What characterizes a ventricular septal defect?

A ventricular septal defect is characterized by the presence of a hole in the septum that separates the heart's ventricles. This anatomical defect allows blood to flow from the left ventricle to the right ventricle, which can lead to increased blood flow to the lungs and potential complications such as pulmonary hypertension or heart failure. This condition is significant because it can affect the heart’s efficiency and the overall circulation of blood within the body.

The other options describe different cardiac conditions: narrowing of the aortic valve refers to aortic stenosis, a condition that affects blood flow from the heart; a blockage in the pulmonary artery generally refers to pulmonary artery obstruction or pulmonary embolism; and abnormal thickening of the heart muscle describes hypertrophic cardiomyopathy. Understanding these distinctions in heart defects is essential for diagnosing and managing various cardiovascular issues.