FRCA Notes

Aortic Regurgitation

Resources

  • Bacterial endocarditis
  • Aortic dissection
  • Rheumatic heart disease
  • Secondary AR due to dilation of the aortic root
    • Connective tissue disease e.g. Marfan's syndrome
    • Ankylosing spondylitis
    • Acquired conditions e.g. tertiary syphilis

  • Volume overload of the left ventricle due to regurgitant blood flow
  • This leads to LV dilatation and eccentric hypertrophy

  • The regurgitant load is determined by afterload and heart rate
    • A lower aortic pressure reduces LV afterload and therefore encourages forward flow
    • A higher HR reduces the time spent in diastole and therefore the time for AR to occur - patients may be tachycardic

Flow-volume loop

  • There is no isovolumetric relaxation
  • There is a higher LVEDP
  • Little-to-no isovolumetric contraction
  • Whole loop is shifted to the right due to increasing LV volumes

  • Acute AR is usually due to a primary cause e.g. endocarditis, aortic dissection
  • It presents with acute LV failure, pulmonary oedema
  • Requires emergency surgical correction

  • Chronic AR develops over years e.g. post-rheumatic fever or due to connective tissue diseases
    • The LV has time to adapt to an increased volume load
    • However, there will eventually be symptoms of LV failure owing to the rise in LVEDP
    • The onset of dyspnoea typically signifies a 2-4yr mortality

Perioperative management of the patient with aortic regurgitation


  • A full history and examination as standard

Investigations

  • ECG: may see voltage criteria for LVH
  • CXR: may see signs of cardiomegaly or (acute) LV failure
  • TTE: assess valve status, ventricular function
    • The pressure half-time index is the time it takes for the initial maximal pressure gradient in diastole to fall by 50%
    • If LV pressure rises rapidly in diastole, the pressure gradient decreases rapidly leading to a low pressure half time
    • LV pressure rises rapidly with greater regurgitant flow and/or lower LV compliance
Classification Pressure half-time
Mild >500ms
Moderate 500-200ms
Severe <200ms
  • Consider pre-operative valve repair in patients undergoing elective non-cardiac surgery with a functional capacity <4 METS (a flight of stairs)

Monitoring

  • AAGBI
  • A-line
  • Consider CVC for inotropic drugs
  • Consider TOE

Haemodynamic goals

Cardiovascular feature Goal of management Rationale
Heart rate Avoid bradycardia (HR >60bpm)
Maintain high-normal HR		 Reduces diastolic time and time for regurgitation to occur
Heart rhythm Maintain sinus rhythm Tolerate AF better than those with AS
Afterload Aim for low-normal SVR Encourages forward flow of blood
Contractility Avoid negative inotropy
Preload Euvolaemia

  • Regional techniques are well tolerated
  • Inodilators are useful as you will get positive inotropy, decreased SVR and some positive chronotropic effect