Mitral regurgitation

Definition

• Incompetent mitral valve allowing backflow across the annulus
• Can be primary, from myxomatous degeneration or senescence, or secondary, from LV dilatation and functional regurgitation

Etiology

• Inflammatory
  • Rheumatic heart disease
  • Lupus
  • Scleroderma
  • Rheumatoid arthritis
• Degenerative
  • Myxomatous degeneration (MVP)
  • Marfan syndrome
  • Ehlers-Danlos syndrome
• Infective endocarditis, after healing
• Structural
  • Ruptured chordae tendinae (spontaneous, post-MI, MVP, trauma, IE)
  • Ruptured or dysfunctional papillary muscle (MI)
  • Mitral annular dilatation from LV dysfunction (also called secondary MR)
  • Hypertrophic cardiomyopathy (due to systolic anterior motion of the MV; SAM)
  • Paravalvular leak of prosthetic valve
• Congenital
  • MV cleft or fenestration
  • Parachute mitral valve

Pathophysiology

• LV compensates by eccentric hypertrophy (increased LV end-diastolic volume)
• LVEF supra-normal >60%
• LA dilates to compensate for MR and maintain normal LA pressure

Grading

• Severe
  • Central jet >40% of LA
  • Holosystolic eccentric jet of MR
  • Vena contracta ≥0.7cm
  • Regurgitant volume ≥60ml
  • Regurgitant fraction ≥50%
  • ERO ≥0.4cm2
  • Other findings: LA enlargement and high RVSP
• Secondary MR
• Severe
  • ERO ≥0.2
  • Regurgitant volume ≥30ml
  • Regurgitant fraction ≥50%
• Progressive
  • Otherwise

Clinical Manifestations

Physical Examination

• Palpation
  • PMI is prominent and displaced left
  • Systolic expansion of LA may be palpable in RSB
• Auscultation
  • Soft S1
  • Widely split S2 (A2 occurs early because decreased forward flow over the aortic valve)
  • Holosystolic, blowing, high-pitched murmur at the apex
  • May hear S3

Investigations

• Consider TEE if severity or mechanism is unclear fro TEE, especially if eccentric jet
• Consider cardiac MRI if volumes are unclear from TTE
• Consider exercise echo if discrepancy between severity on TTE and symptoms

Management

• ACEi, beta blocker, MRA for HFrEF if surgery not planned
• Don't use vasodilators unless hypertensive
• Surgery: repair preferred to replacement when possible
  • Symptomatic severe LVEF >30%
  • Asymptomatic severe with LVEF ≤060% or LVESD ≥40mm
  • Undergoing another cardiac surgery
  • Asymptomatic chronic severe with normal LVEF and dimesion in whome likelihood of successful repair iss >95% and expected mortality <1%
  • Asymptomatic severe with new AFib or resting pHTN
• Secondary MR
  • Treat the LV first per heart failure guidelines
  • Consider CRT (cardiac resynchronization therapy) before valvular intervention
  • Surgery if
    • Undergoing another cardiac surgery like CABG and AVR
    • Consider for severe symptomatic patients