Question 3 : Complications of myocardial infarction

Discuss the use of Echocardiography/Doppler in the assessment of the complications of acute myocardial infarction

Acute/subacute complications

  • Cardiogenic shock
  • Thrombus formation
  • Myocardial rupture
  • Papillary muscle rupture
  • Ischaemic ventricular septum defect

Chronic

  • Remodelling of the heart
  • Aneurysm
  • Right heart failure
  • Late thrombus
  • Mitral regurgitation

Assessment using ECHO

Regional wall abnormalities

  • Will depend on size and coronary artery vessels affected. Need to do full cardiac views to evaluate properly

Cardiogenic shock :

  • Poor LV function on
  • EF : 2D ECHO using fractional shortening (inaccurate if RWA present , requires good PLAX views which are not oblique)
  • EF : Using Simpson’s Method ( (ED vol – ES vol) / EDvol X 100) ( requires good apical 4 chamber and 2 chamber views , takes time)
  • SV : LVOT VTI (cm) X Area of LVOT (requires good 3 or 5 chamber views for LVOT VTI  and good PLAX view to measure diameter of LVOT) Need to get an average of 3 measurements if patient is in AF
  • Measure contractility of LV dP/dt Nomal 1200mmHg /sec , reduced < 800 mmHg/sec   Measure the slope of the regurgitatant MR signal between 1 and 3  m/s (disadvantage need MR, inexact)
  • Size of LV : Normal if less than 5.5 cm but dependent on size of patient. Athletes may have 6cm – normal
  • Eye ball contractility of LV in PLAX and PSAX views and in 4 cardiac windows

Thrombus formation:

  • 2D ECHO to look for thrombus. Need to put the focus in the area of interest. Early on thrombi are completely anechoic and may not be seen
  • Put colour Doppler to check that thrombus does not perfuse
  • Visible in > 1 plane
  • Measure size to monitor treatment effects

Myocardial rupture

  • Pericardial effusion and tamponade
  • Pericardial effusion with associated tamponade
    Echo can assess and measure the effusion and assess haemodynamic effects of tamponade
    RV/RV collapse/LA collapse/Tricuspid inflow inspiratory E wave changes > 40% and inflow changes on expiration >25% through mitral valve

Papillary muscle rupture

  • Rupture of postero papillary muscle is more common than the anterolateral one which had a dual blood supply
  • Severe mitral regurgitation :
  • May have a lack of distinct mitral regurgitation jet due to a large regurgitant orifice and low flow velocity mitral regurgitation – need TEE
  • Triangular shape of mitral regurgitation because of low systolic blood pressure in shock and pressure equilibrium between the left ventricle and the left atrium
  • Flail papillary muscle
  • Left ventricular overload with dilatation of LV

Ischaemic ventricular septum rupture

  • Can see a disrupted interventricular septum (usually distal anterior or basal inferior)
  • Colour Doppler shows flow from LV to RV in systole
  • CW Doppler velocity depends on the size of the rupture and the pressure gradient between the right and left ventricles
  • Elevated pulmonary flow velocities across the pulmonary valve
  • Acute pulmonary hypertension

Aneurysm

  • Dilation and akinesis of aneurysmal area
  • Slow flow phenomenon in aneurysmal area
  • Best views 2CV and atypical views

Right heart  failure

  • Enlarged RV
  • Poor RV contraction

Late mitral regurgitation due to remodelling of the heart assess

  • Colour flow Doppler
  • Difficult to evaluate degree of MR if MR jet is eccentric
  • Look at vena contracta
  • If regurgitant jet on colour Doppler takes up > than 40% of LA then severe

Leave a Reply

Your email address will not be published. Required fields are marked *

Protected with IP Blacklist CloudIP Blacklist Cloud