Mr. Watson has been diagnosed with mitral insufficiency, or a malfunctioning mitral valve, which causes the valve to not close properly. Predict the signs and symptoms you might expect from a disease of this valve. What would happen to the patient's stroke volume and cardiac output? Explain. What might help improve his cardiac output?

Video transcript

Hi, everyone. Let's take a look at this practice problem together with mitral insufficiency, blood leaks backward from the left ventricle into the left atrium during systole. What is the effect of this regurgitation? The answer options are a reduced heart rate. B, reduced contractility, C reduced blood capacity and d decreased stroke volume. So, recall that normal flow during cysto or when the ventricles are contracting is that the blood will flow from the left ventricle to the aorta and then to systemic circulation. Now, with mitral insufficiency, the regurgitation means that there is less blood that will flow to the systemic circulation. So what is the overall effect of that regurgitation option? A reduced heart rate. This is not an effect of the regurgitation. Heart rate is set by the S A node. It is not affected by the amount of blood in the ventricles. So option A is incorrect. Option B, reduced contractility, cardiac muscle cell contractility is not affected by leakage of blood back into the left atrium. So we can eliminate. Option B. Option C reduced blood capacity. This is also incorrect. The blood capacity of the left ventricle is not affected even though there's blood leaking out of the ventricle. The left ventricle can still hold the same amount of blood as it always has. So, the blood capacity is unchanged. The correct answer is decreased stroke volume and recall that decreased stroke volume is the amount of blood pumped in a contraction. So, when blood leaks back into the left atrium, there is less blood to be pumped out of the left ventricle with each contraction. The correct answer is option d decreased stroke volume. All right, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.