Cases

Cases

Focused POCUS in an out-of-hospital cardiac arrest

The content below is supplementary to the poster entitled Focused POCUS in OOHCA.  Click below or scroll to go to the echo clips.

1. Suprasternal view - normal

The suprasternal view is obtained by placing the echo probe above the sternal notch with the  beam pointing down into the chest and the probe marker pointing to the patient’s left shoulder. 

It is part of the FUSIC HD dataset for aortic assessment (see image 2 below).

Image 1: FUSIC HD aortic assessment: Is the aorta abnormal?

Image 2: Anatomy of the aortic arch in the suprasternal view

Normal aortic arch

Normal aortic arch with colour

2. Suprasternal view - case

The flow on colour doppler appeared abnormal (see clip below). Flow is detected away (blue) and towards (red) the probe in the arch of the aorta. This raised our suspicion for an aortic dissection.

Bi-directional colour flow in the aortic arch with 2 distinct flow patterns raising the suspicion of an aortic dissection. Possible dissection flap seen in the arch of the aorta.

3. fTOE views

The TOE probe was inserted to the mid-oesophageal level and without any manipulation of the probe ‘clip 1’ below was obtained. This gave us the diagnosis immediately. 

There was a type A aortic dissection with intimal flap prolapsing through the aortic valve leading to severe aortic regurgitation (clip 1-4). There was also evidence of anterior wall hypokinesia likely from left coronary artery ostia compression from the dissection (see clip 5&6). This also correlated with the ECG changes. The dissection flap extended down the descending thoracic aorta (see clip 7&8).

Mid-oesophageal 5-chamber

Clip 1: Intimal flap at the level of the aortic root prolapsing through the aortic valve in diastole.

Clip 2: Colour doppler demonstrating severe free flowing aortic regurgitation (blue jet in diastole)

Mid-oesophageal aortic valve - short and long axis

Clip 3: Intimal flap at the level of the aortic valve in short axis

Clip 4: Initimal flap prolapse demonstrated in aortic valve long axis view

Mid-oesophageal 2 chamber view

Clip 5: Mid-oesophageal 2 chamber view - anterior wall (right of image) hypokinesia. (Not a good slice through apex of LV - note shortening of apex in systole)

Clip 6: Mid-oesophageal mitral commissural view - anterior wall (right of image) hypokinesia. Better slice through apex of LV.

Mid-oesophageal descending aorta short axis

Clip 7: Intimal flap is seen 'peeling' off the adventia. False lumen is larger than true lumen. The true lumen is extremely small and compressed.

Clip 8: In this case the true lumen is so small and compressed that the colour flow is turbulent and not well seen. This is not in keeping with the general rule that the true lumen has normal colour flow. (See below for other examples).

More information about aortic dissection complications and TOE assessment below. 

4. Aortic dissection

Aortic dissection is caused by an intimal tear (inner layer) in the aortic wall and allows blood to enter into the middle layer (media). This blood travels proximally and distally from the tear and causes the inner and outer wall of the aorta to dissect. 

The commonly used classification is Stanford classification and is classified as:

  • Stanford A – all dissections involving the ascending aorta – these are treated as a surgical emergency.
  • Stanford B – all dissections not involving the ascending aorta – these are managed medically unless complications arise.
Type A aortic dissections have twice the mortality of the type B dissections (25% vs 12%). The commonest cause of death is aortic rupture followed by aortic regurgitation which leads to heart failure and cardiogenic shock.⁵ 

Type A aortic dissection with intimal flap prolapse through the aortic valve

Complications

Common complications of aortic dissection⁵

  • Aortic regurgitation (40-75% of type A)
  • Cardiac tamponade (<20% of type A)
  • Cardiac ischaemia (10-15%)
  • Cardiogenic shock (<10%)
  • Stroke (<10%)
  • Large pleural effusion (15-20%)
  • Lower limb ischaemia (<10%)
  • Organ malperfusion 
    • Spinal cord ischaemia (1%)
    • Mesenteric ischaemia (<5%)
    • Acute renal failure (<20%)
Causes of aortic regurgitation in aortic dissection 
  • Aortic root dilatation – leading to coaptation defect 
  • Cusp prolapse – if the dissection extends and disrupts the attachment of the aortic valve leaflet/s.
  • Dissection flap prolapse – in diastole the the intimal flap prolapses through the aortic valve causing aortic regurgitation.

Intimal flap at the level of the aortic valve

Severe aortic regurgitation caused by intimal flap prolapse

Cardiac ischaemia

This is caused by extension of the false lumen of the dissection causing compression of the coronary ostia. It can also be caused by extension of the dissection down a coronary artery. This will lead to cardiac ischaemia with ST changes on ECG and regional wall motion abnormalities on echocardiography. 

RWMA seen in the anterior wall of the LV (right of the clip) in a patient with type A aortic dissection. There is reduced endocardial excursion and thickening indicating hypokinesia. Compare to the inferior wall (left of image). The false lumen is likely compressing the left coronary artery ostia.

True vs false lumen ⁶

The simplest way to identify the false lumen is most of the time the false lumen is larger than the true lumen. 

True lumen

False lumen

Smaller

Larger

Normal colour flow

Reduced flow on colour doppler

Spontaneous echo contrast

Expands in systole

Intimal flap towards true lumen in diastole

True vs false lumen - true lumen smaller, expands systole, smaller in diastole. False lumen - spontaneous echo contrast.

Normal colour flow on doppler in true lumen (which is smaller than false lumen) and no flow on colout doppler in false lumen.