What type of defect involves valves that prevent blood from flowing in the correct direction?

Valvular defects specifically involve the heart valves failing to open or close properly, which leads to improper blood flow within the heart and to the rest of the body. These defects can include conditions such as stenosis (where a valve doesn't open fully) and regurgitation (where a valve doesn't close completely), both of which obstruct the normal directional flow of blood.

In contrast, coronary artery disease primarily affects the blood supply to the heart muscle itself and is related to the arteries rather than the valves. Cardiomyopathy is a disease of the heart muscle that affects its size, shape, or structure and can lead to heart failure but does not involve the heart valves directly. Arrhythmias are abnormal heart rhythms and also do not specifically concern the functionality of heart valves. Thus, valvular defects are the best choice for the condition that directly involves malfunctioning valves impacting blood flow direction.