Valvular disease - Mitral regurgitation Flashcards
(38 cards)
What is mitral regurgitation?
https://www.youtube.com/watch?v=nY4aaBezu9o
A disorder of the heart in which the mitral valve does not close properly when the heart pumps out blood. It is the abnormal leaking of blood backwards from the left ventricle, through the mitral valve, into the left atrium, when the left ventricle contracts, i.e. there is regurgitation of blood back into the left atrium
What abnormalities can cause mitral regurgitation?
Abnormalities of
- Valve leaflets
- The annulus
- Chordae tendineae
- Papillary muscles
- Left ventricle
Why does blood regurgitate backwards into the atrium?
Due to left atrial pressure being significantly lower than aortic pressure, blood regurgitates through the insufficient valve immediately after the start of ventricular contraction. By the time the aortic valve has opened, the almost a quarter of the SV may have entered the LA.
What happens to the left atrium due to chronic regurgitation?
Left atrial dilatation
What happens to the left atrium due to acute regurgitation?
The normal compliance of the left atrium does not allow much dilatation and the left atrial pressure rises. Thus, in acute mitral regurgitation the left atrial v-wave is greatly increased and pulmonary venous pressure rises to produce pulmonary oedema
In acute MR, what happens to preload?
Increased preload
In acute MR, what happens to afterload?
Decreased afterload
What happens to EDV in acute MR?
Increased EDV
What happens to ESV in acute MR?
Decreased ESV
What happens in response to decreased ESV in acute MR?
LV attempts to contract harder to eject as much blood as possible. This leads to further increased atrial pressure, which causes back pressure into the lungs, leading to PHT and pulmonary oedema
Why is left atrial pressure often normal in chronic compensated MR?
The left atrium has time to accomodate and dilate in repsonse to regurgitant volume
What type of LV hypertrophy develops in MR?
Eccentric hypertrophy
Why does MR worsen with LV hypertrophy?
The mitral annulus may stretch and prevent the mitral valve leaflets from closing properly during systole, thus worsening the MR and LV dilatation.
What is cardiogenic shock?
https://www.youtube.com/watch?v=1Gw0coR2Svo
A life-threatening medical condition resulting from an inadequate circulation of blood due to primary failure of the ventricles of the heart to function effectivelyAs this is a type of circulatory shock, there is insufficient perfusion of tissue to meet the demands for oxygen and nutrients. Cardiogenic shock is a condition that is difficult to fully reverse even with an early diagnosis, and as such is quite often fatal
What happens in chronic uncompensated MR?
In this phase, muscle dysfunction has developed. This results in a higher ESV and EDV, which in turn causes an elevation of LV and LA pressure, ultimately leading to pulmonary oedema and, if left untreated, cardiogenic shock
What are symptoms of acute MR?
- Acute breathlessness
- Symptoms of pulmonary oedema
What signs might you see in someone with acute MR?
- Pulmonary oedema
- Tachycardia
- Hypotension
- Peripheral vasoconstriction
- Pan-systolic murmur of MR
- Signs of RHF
- Cardiogenic shock
What are causes of acute MR?
- Infective endocarditis
- Papillary muscle dysfunction/rupture
- Rupture of chordae tendinae - infection, myxomatous degeneration
- Trauma
- Prosthetic valve malfunction
- Left atrial myxoma
- Acute rheumatic fever
- Marfan’s syndrome
What is an important differential to exclude if someone comes in with acute pulmonary oedema, other than acute MR?
VSD
What symptoms might you find in chronic MR?
- Dyspnoea
- Fatigue
- Palpitations - due to Afib
What signs might you see in someone with chronic MR?
- Displaced, hyperdynamic apex
- Soft S1
- S3
- Sign of PHT - Split S2, Loud P2, RV heave
- Pansystolic murmur at apex, radiating to axilla
- Signs of HF
Why might there be a displaced, hyperdynamic apex in MR?
Due to the eccentric hypertrophy that occurs due to mitral regurgitaiton
Why can the S1 heart sound become softer?
Owing to the incomplete apposition of the valve cusps and their partial closure by the time ventricular systole begins
Why is the murmur heard in MR pansystolic?
Owing to the occurrence of regurgitation throughout the whole of systole, being loudest at the apex but radiating widely over the precordium and into the axilla
