An echocardiogram records an EDV of 150 mL and an ESV of 90 mL. What is the stroke volume?

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  Based on normal values, is this patient's stroke volume within the expected range?

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A. Blood is returned to the left side of the heart via the pulmonary veins.: The pulmonary veins are located posteriorly and return oxygenated blood from the lungs to the left atrium. From the left atrium, blood flows through the mitral (bicuspid) valve into the left ventricle during ventricular diastole. This describes normal anatomic blood flow into the left side of the heart.

B. The left ventricle contracts to push blood through the aortic semilunar valve.: The left ventricle forms the apex of the heart and has the thickest myocardial wall due to its role in systemic circulation. During left ventricular systole, it generates high pressure to open the aortic semilunar valve and eject blood into the ascending aorta.

C. The left ventricle fills after the blood passes through the bicuspid.: The bicuspid valve, also called the mitral valve, is located between the left atrium and left ventricle. During ventricular diastole, blood flows from the left atrium through this valve into the left ventricle. Proper opening of the mitral valve allows adequate ventricular preload before systole.

D. Blood in the left ventricle is deoxygenated.: The left ventricle receives oxygenated blood from the lungs via the left atrium and pulmonary veins. Its physiologic function is to pump oxygen-rich blood into the systemic circulation through the aorta. Deoxygenated blood is found on the right side of the heart, not within the left ventricular chamber.

Correct answer:

• Interventricular septum
• Atrioventricular (AV) bundle / Bundle of His

The highlighted area represents the interventricular septum, the thick muscular wall that separates the right and left ventricles. It forms the medial wall of both ventricles and extends from the atrioventricular valves superiorly to the apex inferiorly. Its primary physiologic function is to prevent mixing of oxygenated blood in the left ventricle with deoxygenated blood in the right ventricle while also contributing to ventricular contraction. The electrical conduction structure that passes through this area is the atrioventricular (AV) bundle / Bundle of His. The Bundle of His passes from the atrioventricular node into the membranous portion of the interventricular septum. It then divides into the right and left bundle branches, which travel along the septum toward the apex to distribute electrical impulses to both ventricles. This allows coordinated ventricular depolarization and synchronized contraction.