Cardiovascular system: Cardiovascular problem Flashcards
What is mitral regurgitation?
A condition in which the heart’s mitral valve doesn’t close tightly, which allows blood to flow backward in the heart.
What causes mitral regurgitation?
Dilated cardiomyopathy - where the ventricle/fibrous ring enlarges so that the mitral valve is unable to close properly
What causes dilated cardiomyopathy?
Cause is often unable to be identified (i.e. idiopathic, unknown condition) but most likely to be a viral infection where the muscle fibres are attacked by lymphocytes causing them to either die or be weakened and stretched
What happens to the mitral valve causing mitral regurgitation?
The mitral valve flaps no longer meet during systole so blood flows through gap
What is the left ventricle : right ventricle ratio of a normal heart vs a heart with dilated cardiomyopathy?
3:1 for a normal and dilated heart
What changes in the heart with a patient with dilated cardiomyopathy? How does this affect heart function?
the lumen is much bigger but the heart wall is relatively thinner so the heart is weaker
What is it called when the mitral valves don’t close properly?
Mitral impotence
Why does the heart develop mitral impotence as the heart enlarges?
The valve is made of collagen so it can’t grow as fast as the left ventricle expands therefore won’t close the gap that is getting larger
Which one of these diagram shows mitral regurgitation pressures in the heart? Why?
B because it shows the left atrium pressure increasing during systole which is what happens when blood flows back into the atrium and the peak pressure of the ventricle is lower. The other two options have continuously elevated pressures of the atrium or ventricle which is not what happens as it is only during VENTRICULAR EJECTION that there is an effect
Which one of these diagram shows mitral regurgitation sounds? Why?
B because there is only unusual sounds during VENTRICULAR EJECTION (i.e. the first segment of heart contraction). The other two options have sounds during filling which is when the mitral valve is open at the correct time
What happens to the lungs of people with elevated blood pressure? What does this lead to?
Their lungs are filled with more fluid
Leads to breathing difficulty
What cardiac circuit has an increased blood pressure due to mitral regurgitation?
The pulmonary circuit
Explain how mitral regurgitation causes breathing problems in patients
1 - Up to half of the blood pumped by the left ventricle is regurgitated per contraction back into the left atrium
2 - In order to maintain cardiac output, assuming the heart rate remains the same, the left ventricle must pump harder for the same stroke volume to get into the aorta
3 - This causes the left atrium pressure to increase which increases the pulmonary venous and capillary pressure (right atrium also pumps harder to push blood back into left atrium FYI)
4 - the capillaries are leaky so an increase in pressure causes more fluid to leak out
5 - This makes the lugs heavier, wetter and more rigid requiring more muscular work in order to breathe = breathing problems (Dyspnoea FYI)
What is dyspnoea?
Discomfort during breathing, consciousness of laboured breathing
How can dilated cardiomyopathy cause a patient to die?
The left ventricle dilates which causes mitral regurgitation which means that the left ventricle stretches in order to increase the amount of blood pumped per stroke increasing blood pressure in the left atrium therefore pulmonary circuit. This however exacerbates mitral regurgitation which causes the left ventricle to expand more increasing the blood pressure further in the pulmonary circuit. This continues until the heart is unable to maintain the systemic circuit = death
