Heart Case Study

1. Caleb has abnormal heart sounds that tipped the doctor off to a problem.

a. Name the normal sounds of the heart and indicate what causes these sounds

The normal sounds of the heart are “lub” and “dub” and they occur with each heartbeat. They are referred to as S1 and S2, respectively. The atrioventricular valves closing causes the first heart sound. This immediately restricts the reverse blood flow and occurs at the beginning of the ventricular systole. The chordae tendinae, which are attached to the valves, become tense and the ventricles squeeze against the semilunar valves, which block the blood flow.

The closing of the semilunar valves causes the second heart sound and occurs at the end of ventricular systole and the beginning of ventricular diastole. As the pressure of the left ventricle falls below the pressure of the aortic valve, the aortic valve closes preventing the reversal blood flow from the left ventricle. As the pressure in the right ventricle falls below the pressure of the pulmonary artery, a similar situation occurs as the pulmonary valve closes. This results in the second sound of the heart.

These are the two main heart sounds that are heard in a heartbeat, but there are more subtle sounds that can be heard. For example, a protodiastolic/ventricle gallop, a presystolic/atrial gallop, but they don’t occur as often.

2. The defect in Caleb’s heart allows blood to mix between the two ventricular chambers.

b. Due to this defect would you expect the blood to move from left-to-right ventricle or right-to-left ventricle during systole?

The blood would most likely moved from the left ventricle to the right ventricle because in the case of a ventricular septal defect, the blood is mixed between the two chambers and so there is more blood being pumped into the lungs than normal.

c. Based on your understanding of blood pressure and resistance in the heart and great vessels, explain your answer to question 3a....