Parasternal short axis view (PSAX)

How to acquire PSAX views?

The PSAX views are obtained by rotating the transducer 90 degrees clockwise from the PLAX view.

The marker is now pointing towards the left shoulder (2 o’clock) and the beam is perpendicular to the long axis of the left ventricle.

Image 1 Position of the TTE probe - the marker is now pointing towards the left shoulder (2 o’clock)

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!!! By tilting the transducer up or down we can view multiple anatomic structures. 

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Which views do we need to obtain in PSAX ? :

1) PSAX - aortic valve level view

2) PSAX at Mitral Valve Level

3) PSAX at the Papillary Muscle level

4) PSAX at the Apex level

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1) PSAX - aortic valve level view

• Tilt the transducer superiorly and medially while the marker is still pointing towards the left shoulder
• Cross Section of aorta above the valve should be at the centre
• This view enables visual assessment of the Aortic Valve, RVOT, PA, PV, TV and interatrial septum (IAS)

Video 1 Normal aortic valve with three cusps in the centre - PSAX at the aortic valve and right ventricular outflow tract

Image 2 Aortic valve level view anatomy

‍Aortic Valve assessment

• Make a clip of the zoomed AV to demonstrate leaflet number and motion
• Assess cusp mobility and commissural fusion
• Assess valve calcification and thickening
• Zoomed AV image with CFD (colour flow Doppler) is recommended.
  

Video 2 Normal aortic valve with three cusps in the centre - PSAX at the aortic valve and right ventricular outflow tract, Colour flow doppler

Video 3 Normal aortic valve with three cusps in the centre, zoomed - PSAX at the aortic valve and right ventricular outflow tract

‍Tricuspid valve assessment

• adjust the sector to the tricuspid valve
• assess leaflet mobility, calcification and anatomy of TV
• Place the CFD over the TV to assess tricuspid regurgitation
• CWD (Continuous Wave Doppler) of assessment of mean pulmonary arterial pressure may be performed in this view

Video 4 Normal tricuspid valve with mild regurgitation - PSAX at the aortic valve and right ventricular outflow tract, CFD

Interatrial septum integrity assessment

• Zoom to the interatrial septum and apply CFD
• Watch out for any trans-septal flow
• The IAS is more commonly evaluated on TOE with contrast

Video 5 Interatrial septum intergrity assessment

Video 6 Interatrial septum intergrity assessment - Colour Doppler used

PSAX at the level of the great vessels (aorta and pulmonary artery)

• Tilt the transducer superiorly and medially while the marker is still pointing towards the left shoulder
• Cross Section of aorta above the valve should be at the centre
• RVOT, PV and the main PA bifurcation to left and right branches are visualized

‍Video 7 PSAX Right ventricular outflow tract view

Image 3 PSAX Right ventricular outflow tract view anatomy

‍RVOT measurement

• Proximal and distal measurements of RVOT are made in this view at end-diastole
• RVOT diameter in PSAX is more reproducible than in PLAX

RVOT 1 (proximal)

• is measured at end-diastole
• A caliper is placed at the interface of the compacted myocardium anterior RV wall and RV cavity and a line is extended to the aortic root.
  

RVOT 2 (distal)

• is measured at end-diastole
• The diameter is measured immediately proximal to the PV with inner edge-to-inner edge technique

‍Image 4 Proximal and distal RVOT measurement both in one picture

Main Pulmonary Artery (PA) diameter

• Measure in end-diastole
• Halfway between the pulmonary valve and the PA bifurcation or at 1 cm above the PV
• Use the inner edge-to-inner edge technique
• A PA diameter of >25mm measured by TTE is considered an indirect sign of pulmonary hypertension

Image 5 Pulmonary artery diameter = 25 mm

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2) PSAX at Mitral Valve Level

• Tilt the transducer towards the heart’s apex – inferiorly and slightly to the left till you see the whole Mitral Valve
• The anterior, lateral and inferior walls of the LV are visible
• The RV is seen at the top left part of the sector

‍MV morphology is assessed in this view

• visualize all 6 scallops of the anterior A1/A2/A3 & posterior P1/P2/P3 leaflets and both commissures entirely
• planimetry of the MV area is performed by tracing the orifice in a frozen frame where the valve is at a point of maximal opening
• Apply CFD to assess presence of any regurgitant jets

‍LV wall motion of the basal segments

• Using the Eyeballing method, the LV function is assessed 
• Observe the wall thickening and endocardial motion of the basal myocardial segments pictured in the schematic below – the segments 1-6 (Image 6)

https://www.annals.in/viewimage.asp?img=AnnCardAnaesth_2009_12_2_174_53438_b2.jpg

‍Video 8 PSAX at mitral valve level

‍Image 6 PSAX Mitral valve level anatomy

Video 9 Normal mitral valve with mild regurgitation - PSAX at mitral valve level, Colour flow Doppler

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3) PSAX at the Papillary Muscle level

• further inferior tilt of the transducer below the MV leaflets tips reveals papillary muscles and the whole circumference of the LV
• LV should appear circular and the papillary muscles don’t wobble
• LV global and regional wall motion and RV wall thickness is assessed

LV wall mobility

• Using the Eyeballing method, the LV function is assessed 
• Observe the wall thickening and endocardial motion of myocardial segments at mid level of the papillary muscles – the segments 7-12 on the schematic above (More in Systolic dysfunction)
• Apply CFD to assess integrity of the interventricular septum

Video 10  PSAX - papillary muscle level - normal wall motion

Image 7 PSAX - Papillary muscle level anatomy

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4) PSAX at the Apical level

• tilt the transducer inferiorly or slide the transducer 1-2 interspaces lower and laterally to acquire view of the apical third of LV and the apex
• Make the LV appear round in shape, no papillary muscles should be seen
• Look for: any abnormality in shape or motion, apical aneurysm, apical thrombus, pericardial effusion, apical wall thickness (hypertrophic CM, no-compaction CM), LV wall mobility of the apical segments (anterior, septal, inferior, lateral and the apex itself)

Video 11 PSAX - Apical level - normal wall motion

Image 8 PSAX - Apical level anatomy

References

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3. Ayan R Patel, MD (2021). Transthoracic echocardiography: Normal cardiac anatomy and tomographic views. In I. Susan B Yeon, MD, JD, FACC (Ed.), UpToDate. Retrieved August 4, 2021 from https://www-uptodate-com.ezproxy.is.cuni.cz/contents/transthoracic-echocardiography-normal-cardiac-anatomy-and-tomographic-views?search=echocardiography%20chambers&source=search_result&selectedTitle=5~150&usage_type=default&display_rank=5
4. CAMM, A. J., LÜSCHER, T. F., & SERRUYS, P. W. (2009). The ESC textbook of cardiovascular medicine. Oxford, Oxford University Press
5. http://pie.med.utoronto.ca/tte/TTE_content/standardviews.html#introduction
6. Galiè N, Humbert M, Vachiery JL, Gibbs S, Lang I, Torbicki A, Simonneau G, Peacock A, Vonk Noordegraaf A, Beghetti M, Ghofrani A, Gomez Sanchez MA, Hansmann G, Klepetko W, Lancellotti P, Matucci M, McDonagh T, Pierard LA, Trindade PT, Zompatori M, Hoeper M; ESC Scientific Document Group. 2015 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension: The Joint Task Force for the Diagnosis and Treatment of Pulmonary Hypertension of the European Society of Cardiology (ESC) and the European Respiratory Society (ERS): Endorsed by: Association for European Paediatric and Congenital Cardiology (AEPC), International Society for Heart and Lung Transplantation (ISHLT). Eur Heart J. 2016 Jan 1;37(1):67-119. doi: 10.1093/eurheartj/ehv317. Epub 2015 Aug 29. PMID: 26320113.