Mitral regurgitation

Question 1

Definition + normal mechanism preventing mitral regurg?

Answer 1

Incompetent (floppy) mitral valve allows backflow of blood from LV to LA during systole
- normally during systole, the papillary muscles contract→ chordae tendinae are pulled taut to close the 2 mitral valve cusps & prevent them prolapsing into the LA

Question 2

Causes & RISK FACTORS (5)

Answer 2

MOST COMMON = myxomatous degeneration of mitral valve (chordae tendinae are weakened so can’t be pulled taut to shut valve cusps)- associated with connective tissues disorders Marfan’s & Ehlers Danlos syndrome
- rheumatic fever
- infective endocarditis (if fever & new regurgitant murmur → suspect IE as DDx)
- papillary muscle rupture/dysfunction e.g. post-MI

Risk factors = CT disorders, females, old age, low BMI, previous MI

Question 3

Pathophsyiology

Answer 3

Incompetent (floppy) mitral valve allows backflow of blood from LV to LA during systole→ volume overload in left side of heart→ backlogged blood in pulmonary vessels causes pulmonary hypertension & right heart failure
- LV has reduced ejection fraction so develops systolic heart failure- congestive heart failure
- LV undergoes compensatory hypertrophy in response to volume overload & increased preload. Eventually LV fails & RV fails (due to pulmonary hypertension) = CHF
- LA dilates due to volume overload → atrial fibrillation

Question 4

Signs

Answer 4

• Pansystolic murmur radiating to left axilla (continuous murmur THROUGHOUT systole as blood is flowing back from LV → LA)
• Soft S1 heart sound (2 valve cusps don’t close properly)
• S3 heart sound in severe cases of congestive heart failure (heard in early diastole

Signs of heart failure: raised JVP, hepatomegaly (due to congestion in hepatic veins), bi-basal crackles on auscultation (due to pulmonary oedema)

Question 5

Symptoms

Answer 5

• Dyspnoea on exertion + exercise intolerance (pulmonary hypertension from backlogged blood CO)
• Fatigue
• Symptoms of heart failure: peripheral/ankle oedema, palpitations, orthopnoea, paroxysmal nocturnal dyspnoea, productive cough with pink frothy sputum (due to pulmonary oedema)

Question 6

Diagnosis

Answer 6

• GS = transoesophageal echocardiogram -assess LA & LV size & function
• CXR (not diagnostic, may show LA enlargement & pulmonary artery enlargement)
• ECG- may show atrial fibrillation- absent P waves, narrow QRS complexes, irregularly irregular rhythm. P mitrale = bifid P waves due to left atrial enlargement, been seen in lead II

Question 7

Treatment

Answer 7

MEDICAL treatment (if ejection fraction >60%/not severe):
- Vasodilators (ACE-i) - to decrease afterload & increase forward flow in a volume overloaded heart
- Beta blockers for rate control (-ve inotoropes, -ve chronotropes, prevent progression to CHF)
- AND serial transoesophageal echocardiogram monitoring
SURGICAL repair of mitral valve/ replacement if ejection fraction < 60%

Question 8

Treatment

Answer 8

MEDICAL treatment (if ejection fraction >60%/not severe):
- Vasodilators (ACE-i) - to decrease afterload & increase forward flow in a volume overloaded heart
- Beta blockers for rate control (-ve inotoropes, -ve chronotropes, prevent progression to CHF)
- AND serial transoesophageal echocardiogram monitoring
SURGICAL repair of mitral valve/ replacement if ejection fraction < 60%