Mitral Regurgitation

Question 1

Define Mitral Regurgitation

Answer 1

Retrograde flow of blood from left ventricle to left atrium during systole due to mitral valve insufficiency

Question 2

Explain the aetiology/risk factors of mitral regurgitation? (2 mechanisms)

Answer 2

Functional Mitral Regurgitation

• Papillary muscle/Tendinous Chords rupture (post-MI) these muscles pull on tendinous cord to prevent eversion - MOST COMMON
• DILATED CARDIOMYOPATHY dilates the annulus/root

Disease of the leaflet itself

• Mitral valve prolapse (caused by myxomas /nodular growths on the valve)
• Rheumatic Heart disease
• Infective Endocarditis

Question 3

Explain aetiology and symptoms in ACUTE MR

Answer 3

• Acute mitral regurgitation classically occurs with a spontaneous chordae tendineae or papillary muscle rupture secondary to myocardial infarction.
• Ventricular Systole causes an sudden retrograde flow of blood at high pressure into a non-compliant atrium which equalises the pressure gradient - casuing increased pressures in both LA & LV
• In this state, a sudden volume and pressure overload occurs on an unprepared left ventricle and left atrium, with an abrupt increase in left ventricular stroke work.
• Increased LV filling pressures, combined with the reflux of blood from the LV into the LA during systole, results in elevated left atrial pressures.
• This increased pressure is transmitted to the lungs, resulting in:
  
  • Acute ‘flash’ pulmonary edema and consequently acute dyspnea, Wheeze (cardiac asthma) & diaphoresis

Question 4

Recognise the presenting symptoms (5)

Answer 4

Chronic MR - may be asymptomatic for a few years as LV & LA undergo hypertrophy to cope with increased pressures - this then leads to systolic HF which presents with:

MR has no pathognomic signs

1. Exertional dyspnoea (usually first)
2. Orthopnea
3. PND
4. Palpitations if in AF (LA dilation)
5. RHF symptoms
   
   • Leg swelling
   • RUQ pain (hepatic congestion)
   • Abdominal distension

Question 5

Recognise the signs of mitral regurgitation on physical examination

Answer 5

• Pansystolic murmur loudest at the apex, radiating to the axilla (get patient to do left lateral decubitus position)
• Mid-systolic click if mitral valve prolapse (as opposed to ejection click heard in bicuspid aortic valve)
• Diminished S1 as valves don’t close
• Loud P2 due to pulmonary HTN
• S3 & Laterally displaced apex beatndue to volume overload (systolic failure)
• Irregularly irregular pulse (if in AF due to LA dilation)
• Bi-basal crepitations
• Signs of RHF

Question 6

Identify appropriate investigations for mitral regurgitation and interpret the results

Answer 6

• ECG
  
  • NORMAL
  • May show AF or previous MI
• Echocardiography
  
  • Assess valve function and aetiology
  • Doppler echo to assess size and site of regurgitant jet​