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Parasternal Long-Axis Echocardiogram View

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Parasternal Long-Axis Echocardiogram View, PLAX View, E-point Septal Separation, EPSS, Aorta Diameter Measurement on PLAX View, Aortic Dissection on PLAX View

  • Background
  1. Improved window (bring heart closer to transducer and reduce rib shadowing)
    1. Patient positioned in left lateral decubitus position (if possible)
    2. Start along sternal border near the 3rd interspace and check several interspaces inferiorly and laterally (to left)
    3. View improves when patient breathes out
    4. More difficult view in COPD or Asthma
    5. Preferred view in Obesity, pregnancy or Ascites (increased abdominal pressure pushes the heart upward into the chest)
  2. Transducer orientation
    1. Transducer 3-5 cm to the left of the left sternal border at the 3rd to 5th intercostal space
    2. Transducer indicator pointed towards patient's right Shoulder (10:00 position) in cardiac mode
  • Technique
  1. Images
    1. UltrasoundHeartPLAXAndPSAX.jpg
    2. ultrasoundProbePositionEchoPLAX.jpg
    3. ultrasoundBMP_cvPLAX2.jpg
    4. PLAX.png
  2. Standard Parasternal Long Axis (PLAX) Landmarks
    1. Right ventricle or right ventricular outflow tract
    2. Left ventricle, aortic valve and proximal aorta
    3. Mitral valve and left atrium
    4. Descending Aorta
  3. Parasternal Long Axis Right Ventricular Inflow Landmarks (tilt toward right hip)
    1. Right Ventricle
    2. Tricuspid Valve Leaflets
    3. Right Atrium and right atrial appendage
    4. Eustachian Valveand distal inferior vena cava
    5. Coronary Sinus
  4. Parasternal Long Axis Right Ventricular Outflow Landmarks (tilt toward left Shoulder)
    1. Right Ventricular Outflow Tract, Pulmonic Valve and Pulmonary Artery
    2. Left Ventricle, Mitral Valve and Left Atrium
  • Interpretation
  • General
  1. Approach
    1. Visualizes the positions of the parasternal short axis cross sections (see below)
    2. Wall motion abnormalities (especially apex and septum)
    3. Valvular insufficiency (Mitral Regurgitation or Aortic Insufficiency) with color doppler
    4. Aortic root dilation (best imaged with same probe orientation but at the 3rd intercostal space)
  2. Measurements: 2D
    1. End-Diastole (maximal left ventricular dilation, when both aortic and mitral valves are closed)
      1. PLAX_End_Diastole.png
      2. Ultrasound machines typically have combined echo measurements
        1. All three of the following measurements are typically recorded by placing 4 points along a line
      3. Measure along diagonal line perpendicular to the LV long axis
        1. Line passes through the end of the closed distal mitral valve tips
        2. Measure IVSd: Intraventricular Septal width in diastole (immediately below the RVOT)
        3. Measure LVIDd: Left ventricular internal diameter in diastole
        4. Measure IVPWd: The inferior (posterior) wall width in diastole (inside the bright pericardial band)
      4. Measure aortic root diameter
        1. Measure AoRDd: Aortic root diameter in diastole (leading edge to leading edge)
      5. Measure ascending aorta (may require shifting up one rib space to visualize ascending aorta)
        1. The first 3 of these measurements are all considered part of the aortic root
        2. Measure aortic annulus (normal <=2.6 cm)
        3. Measure sinus of valsalva (bulge at proximal aorta, origin of coronary arteries, normal <=3.5 cm)
        4. Measure sino-tubular junction (sinuses of valsalva, normal <=3.4 cm)
        5. Meaure ascending aorta (normal <=3.4 cm)
    2. Early-Systole (just as the aortic valves have completely opened)
      1. PLAX_EarlySystole.png
      2. Measure Left Ventricular Outflow Tract
        1. Measure LVOT: LV Outflow Tract (inner edge to inner edge)
          1. LVOT is frequently underestimated
    3. End-Systole (smallest left ventricle diameter with mitral valves and aortic valves closed)
      1. PLAX_end_systole2.png
      2. Measure Left Ventricle Diameter (along same diagonal line perpendicular to the LV long axis measured in diastole)
        1. Line passes through the end of the closed distal mitral valve tips
        2. Measure LVIDs: Left ventricular internal diameter in diastole
      3. Measure Left Atrium Diameter
        1. Measure LAs: Left atrium (leading edge to leading edge) and starting at aortic sinuses
  3. Measurements: M-Mode
    1. Aortic Valve and Aortic Root
      1. Aortic Root End-Diastolic Diameter (AoRd)
        1. Anterior aortic root to posterior aortic root (leading edge to leading edge) at end-diastole (lowest point)
      2. Left Atrial End-Systolic Diameter (LAs)
        1. Greatest vertical distance (maximal atrial filling) between posterior aortic wall and left atrial wall
      3. Aortic Valve Systolic Separation (ACS)
        1. Maximal distance between aortic cusps
    2. Mitral Valve
      1. Appears as 2 peaks, the E point representing diastolic filling and the A point representing the atrial kick
      2. E-F Slope
        1. Represents filling of the left the ventricle via the mitral valve
        2. Normally the E-F slope is relatively steep
        3. However in Mitral Stenosis it is more flat and the E wave merges into the A wave
          1. Flattening may also occur in severe Diastolic Dysfunction (noncompliant left ventricle)
      3. D-E Excursion
        1. Maximal excursion of the anterior mitral valve leaflet (height of the E Wave)
      4. E Point Septal Separation (EPSS)
        1. Distance between the E-point to the lowest intraventricular septum point
    3. Left Ventricle (measured with line perpendicular to LV long axis through the end of the closed distal mitral valve tips)
      1. Similar measurements to the 2D left ventricular measurements may be obtained
      2. End-Diastole (maximal left ventricular dilation, when both aortic and mitral valves are closed)
        1. Right Ventricular Internal Diameter in end-diastole (RVIDd)
        2. Intraventricular Septal Diameter in end-diastole (IVSDd)
        3. Left Ventricular Internal Diameter in end-diastole (LVIDd)
        4. Left Ventricular Posterior (inferior) Wall Diastolic diameter in end-diastole (LVPWd)
      3. End-Systole (smallest left ventricle diameter with mitral valves and aortic valves closed)
        1. Intraventricular Septal Thickness in end-systole (IVSs)
        2. Left Ventricular Internal Diameter in end-systole (LVIDs)
        3. Left Ventricular Posterior (inferior) Wall Diastolic diameter in end-systole (LVPWs)
  4. Visualization: Color Flow Doppler
    1. PLAX_color_flow_doppler.png
    2. Standard PLAX View with color directed over both the Aortic valve and Mitral valve regions
      1. Single view can demonstrate Aortic Regurgitation, Aortic Stenosis, Mitral Regurgitation and Mitral Stenosis
  1. Decreased contractility of left ventricle
    1. Normal
    2. Depressed or severely depressed
    3. Hyperdynamic
  2. Decreased ejection fraction
    1. Precaution
      1. PLAX View estimate of EF (fractional shortening) is a less ideal estimate than the apical view biplane method
      2. The PLAX View-based EF assumes symmetric left ventricular function, allowing for a single point of measure
    2. Gross Estimate
      1. Estimate visually what percentage difference is seen between the left ventricle volume in systole and diastole
      2. M-mode compare end-systolic (ESD) and end-diastolic (EDD) diameters
    3. Linear calculation: Ultrasound calc package (Fractional Shortening or FS)
      1. In M-Mode or 2D, measure left ventricle end-diastolic (LVIDd) and end systolic (LVIDs) internal diameters
      2. Fractional Shortening = 100 * (LVIDd - LVIDs) / LVIDd
        1. Normal women: 27 to 47% (contrast with normal EF >=55%)
        2. Normal men: 25 to 43% (contrast with normal EF >=55%)
  3. Dilated left ventricle (end diastolic diameter >56 mm)
    1. Measure across widest point between septum and posterior wall
    2. Chordae tendinae may obscure true posterior wall
  4. E-point Septal Separation (EPSS) on M-Mode or cine
    1. Distance between the septum and the mitral valve leaflet when maximally open
    2. Normal is <8-10 mm (>13 mm is correlated with an EF<30%)
  5. Aorta Diameter Measurement on PLAX View (for Aortic Dissection)
    1. Evaluate for Thoracic Aortic Dissection (Type A)
    2. Obtain Parasternal Long-Axis Echocardiogram View (PLAX View)
    3. Measure the maximal distance between anterior and posterior walls of aorta
      1. Probe should be perpendicular to the two aorta walls
      2. Distance >4 cm is concerning for Aortic Dissection (aortic root is normally 2 to 3.5 cm)
      3. Other suggestive findings: Pericardial Effusion, flap within the aorta
  • Interpretation
  • Other findings
  1. Mitral valve stenosis
    1. Vitral valve will have a hockey stick appearance at flap distal end (curving away from septum)
    2. Incomplete opening of the mitral valve septum
  • Resources
  1. Parasternal Long Axis View Video (Sonosite)
    1. http://www.youtube.com/watch?v=4qerzEW_ASU
  2. Echocardiographer
    1. http://echocardiographer.org/
  • References
  1. Palma, Bourque and Jordan (2019) Introduction to Adult Echo Ultrasound Conference, GulfCoast Ultrasound, St. Petersburg
  2. Jordan (2019) Cardiac Ultrasound Protocol Manual, Gulfcoast Ultrasound, p 13-22
  3. Mateer and Jorgensen (2012) Introduction and Advanced Emergency Medicine Ultrasound Conference, GulfCoast Ultrasound, St. Pete's Beach
  4. Noble (2011) Emergency and Critical CareUltrasound, Cambridge University Press, New York, p. 61-88
  5. Orman, Dawson and Mallin in Majoewsky (2013) EM:Rap 13(1): 4-6
  6. Reardon (2011) Pocket Atlas Emergency Ultrasound, McGraw Hill, New York, p. 61-106
  7. Reynolds (2018) The Echocardiographer's Pocket Reference, Arizona Heart Association, p. 323-4