| Leaflet MR | Chordal MR | Papillary MR |
| Endocarditis | Endocarditis | Papillary muscle dsyfunction e.g. MI |
| Rheumatic fever | Chordae rupture post-MI | |
| MV prolapse |
- LV failure (of any aetiology) may cause varying degrees of MR due to annular dilatation
Mitral Regurgitation
Mitral Regurgitation
Resources
- Mitral regurgitation is relatively common; the prevalence of moderate-severe MR is 10% by 75yrs
- Unlike AR, the regurgitant load occurs in ventricular systole
- The degree of regurgitation is determined by afterload, the size of the regurgitant orifice and the heart rate
- There is peripheral vasodilation to lower SVR and encourage forward flow
- There is progressive LA dilatation in order to keep LA pressure low
- Pulmonary congestion may present late
- To compensate for the reduced forward flow, the left ventricle becomes dilated and hypertrophied
- Once the regurgitant fraction is >60% of stroke volume there's compromised cardiac output and worsening congestive cardiac failure
- The regurgitant jet area can be assessed at TTE:
- <4cm2 = mild disease
- >8cm2 = severe disease
Flow-volume loop
- Increased area i.e. increased stroke work
- Normal isovolumetric relaxation
- Increased LVEDP
- No isovolumetric contraction as there is regurgitation
Medical
- Diuretics or nitrates to reduce filling pressures
- Reduce afterload with vasodilators
- Medical management of heart failure e.g. ACE-I, aldosterone antagonists
Interventional
- Use of an intra-aortic balloon pump as a bridge to surgery
- Transcatheter mitral valve repair
- Surgical repair or replacement
Perioperative management of the patient with MR
- History and examination as standard
Investigations
- BNP; low BNP has high NPV for further complications
- ECG; may show signs of (old) inferior infarct causing papillary muscle rupture
- TTE
- Assess valve function
- Assessment of LV function is difficult because the normal ejection fraction in MR is high (~70%) due to bidirectional ejection of blood
- An EF of ≤60% in MR may indicate LV dysfunction
- CPET
Monitoring and access
- AAGBI
- A-line
- ±CVC
- ±TOE
Haemodynamic goals
| Cardiovascular feature | Goal of management | Rationale |
| Heart rate | Avoid bradycardia (HR >60bpm) Maintain high-normal HR (80-100bpm) |
Reduces diastolic overdistension of the LV |
| Heart rhythm | Maintain sinus rhythm | Tolerate AF better than those with stenotic lesions |
| Afterload | Aim for low-normal SVR Avoid factors increasing PVR |
Encourages forward flow of blood |
| Contractility | Avoid negative inotropy | Positive inotropes increase CO and constrict MV annulus, reducing regurgitant area Ephedrine may be better than pure ɑ1-agonists for hypotension |
| Preload | Euvolaemia | Avoid excessive IV fluid as may exacerbate MR |
- HDU care
- LV dysfunction may be unmasked by loss of low-pressure route for ejection of blood i.e. backwards into the low-pressure left atrium
- This may necessitate use of inotropes, inodilators and an IABP until the ventricle adapts