Mitral Regurgitation

Question 1

what is the definition of mitral regurgitation?

Answer 1

• Backflow of blood from the left ventricle to the left atrium during systole

Question 2

what is the epidemiology of mitral regurgitation?

Answer 2

• Mild physiological mitral regurgitation (MR) is seen in 80% of normal individuals

Question 3

what is the aetiology of mitral regurgitation?

Answer 3

Most frequent cause is myxomatous degeneration (MVP) (weakening of the chordae tendinae) - resulting in a floppy mitral valve that prolapses (mitral valve prolapse) 
- Other causes include: 
• Ischaemic mitral valve 
• Rheumatic heart disease 
• Infective endocarditis 
• Papillary muscle dysfunction/rupture 
• Dilated cardiomyopathy

Question 4

what are the risk factors for mitral regurgitation?

Answer 4

• Associated with females
• Lower BMI
• Advanced age
• Renal dysfunction
• Prior MI

Question 5

what is the pathophysiology of mitral regurgitation?

Answer 5

• Regurgitation into the left atrium produces left atrial dilatation but little increase in left atrial pressure if the regurgitation is longstanding, since the regurgitant flow is accommodated by the large left atrium
• Pure volume overload due to leakage of blood into left atrium during systole
• Compensatory mechanisms: Left atrial enlargement, left ventricle hypertrophy (since left ventricle must put in same effort to pump less blood (due to regurgitation) so needs to pump harder to maintain cardiac output and thus hypertrophy to increase stroke volume) and increases contractility:
  • Progressive left atrial dilatation and right ventricular dysfunction due to pulmonary hypertension
  • Progressive left ventricular volume overload leads to dilatation and progressive heart failure

Question 6

what are the key presentations of mitral regurgitation?

Answer 6

Acsculation abnormalities, dyspnea on exertion
lower extremity oedema
risk factor presence

Question 7

what are the heart sounds associated with mitral regurgitation?

Answer 7

Soft S1 and a pan systolic murmur at the apex radiating to the axilla
Prominent third extra heart sound (S3) in congestive heart failure/left atrium overload
Increased stroke volume
Right heart failure
Heart failure

Question 8

what are the symptoms of mitral regurgitation?

Answer 8

Exercise intolerance
Dyspnea
Fatigue
palpitations

Question 9

what are the first line and gold standard investigations for mitral regurgitation?

Answer 9

• ECG:
  • May show left atrial enlargement, atrial fibrillation and left ventricle hypertrophy in severe MR
  • But not diagnostic
  transthroacic echo - presence and severity of MR; other structural and flow abnormalities

Question 10

what other investigations could be done for mitral valve regurgitation?

Answer 10

• CXR:
  • Left atrial enlargement and central pulmonary artery enlargement
• Echocardiogram:
  • Estimation of left atrium and left ventricle size and function
  • Also gives valve structure assessment
  • Transoesophageal is very helpful

Question 11

what are the differential diagnoses for mitral regurgitation?

Answer 11

ACS, inferctive endocarditis, Other mitral and aortic valve diseases, MI, prolapsed valve

Question 12

how is mitral regurgitation managed?

Answer 12

• Indications for surgery:
  • Any symptoms at rest or exercise then initiate repair if feasible
  emergency surgery, preoperative diuretics and intra-aortic balloon counterpulsation
• Medications:
  • Vasodilators such as ACE-inhibitors e.g. Ramipril or Hydralazine (smooth muscle relaxer)
  • Heart rate control for atrial fibrillation with Beta blockers (Atenolol), Calcium channel blockers and digoxin
  • Anticoagulation in atrial fibrillation and flutter
  • Diuretics for fluid overload e.g. Furosemide
  • Asymptomatic:
• If ejection fraction is less than 60%
• If new onset atrial fibrillation

Question 13

how is mitral regurgitation monitored?

Answer 13

• Serial echocardiography:
  • Mild: 2-3 years
  • Moderate: 1-2 years
  • Severe: 6-12 months

Question 14

what are the complications of mitral regurgitation?

Answer 14

Atrial fibrillation
Pulmonary artery hypertension
Dilation of the heart
Heart failure
Bacterial infection of the heart valves

Question 15

what is the prognosis of mitral regurgitation?

Answer 15

• Compensatory phase: 10-15 years
• Once patients ejection fraction becomes less than 60% and/or becomes symptomatic then mortality rises sharply
• Severe mitral regurgitation has a 5%/year mortality rate