LV function echocardiography

LV Function and Haemodynamic Assessment Echocardiography

SYSTOLIC FUNCTION

Global Function

• stroke volume: end-diastolic volume – end-systolic volume
• cardiac output:

Q = SV X HR
= (Aortic Area x V x Tej) x HR

Q = cardiac output
Aortic area = cross sectional area
V = velocity for each beat
Tej = time period during ejection
HR = heart rate

• ejection fraction: take two orthogonal views (apical four chamber and apical two chamber) ⇒ trace around endocardial border at the end of diastole and systole

EF = (EDV-ESV/EDV) x 100
(normal = 50-85%)

• fractional shortening: percentage change in LV internal dimensions between systole and diastole (normal 30-45%)
• preload: end-diastolic volume (if low think -> hypovolaemia, low SVR, severe AR or MR, VSD)
• afterload: end-systolic wall stress (rarely used in clinical practice)
• LV wall thickness: > 1.5cm = LVH, < 0.6cm = LV thinning

Regional Function

• 16 segments
• contractility: grades
  1 = normal or hyperkinetic
  2 = hypokinetic
  3 = akinetic
  4 = dyskinetic (paradoxical systolic motion)
  5 = aneurysmal

DIASTOLIC FUNCTION

• relaxation requires energy (ATP)
• phases of relaxation = isovolumetric relaxation, early filling, diastasis (when LA passively fills LV and then stops), atrial contraction
• diastolic dysfunction = disorder of LV filling where LV is unable to fill to a normal LVEDV without an increase in end-diastolic pressure.
• m-mode ‘slow relaxation’ in motion of the anterior mitral valve leaflet.

• normal = E > A
• abnormal = A > E
• pseudonormal = E > A (LA dilated to compensated for lack of LV relaxation)
• restrictive = E >>> A

References and Links

• Echo: Left ventricular systolic function