Cardiac: Parasternal Long Axis

Indication: Cardiac function assessment; effusion; valve pathology

How to Perform

1
Position patient supine or slight left lateral decubitus. Select phased array probe.
2
Place probe at 3rd–4th ICS, left sternal border, marker pointing to right shoulder.
3
Rotate probe until the cardiac long axis is aligned — LV, MV, aorta, and LA should all be in view.
4
Optimize depth so the descending aorta is just visible at the bottom of the screen.
5
Measure EPSS (E-point septal separation) in M-mode through the mitral valve — >1cm suggests reduced EF.
6
Measure LV internal dimension, posterior wall, IVS, LA diameter, and aortic root in 2D or M-mode.
7
Check posterior pericardial space for effusion. Note valve morphology and mobility.

LV End-Diastolic Diameter (LVEDD)

Where:M-mode or 2D at the level of the mitral valve leaflet tips, inner edge to inner edge, at end-diastole (largest LV dimension, onset of QRS).

Normal:3.9–5.3 cm (women); 4.2–5.9 cm (men); > 6.0 cm = dilated

Tip:Use M-mode through the PLAX view at the tip of the anterior mitral leaflet. Perpendicular to the long axis of the LV.

LV End-Systolic Diameter (LVESD)

Where:Same position as LVEDD, measured at end-systole (smallest LV dimension, peak of T-wave).

Normal:2.3–3.9 cm (women); 2.5–4.0 cm (men); > 4.0 cm = systolic dysfunction

Tip:Fractional shortening (FS) = (LVEDD − LVESD) / LVEDD × 100. Normal FS > 25%.

Interventricular Septum (IVS) Thickness

Where:Diastolic thickness of the IVS at the same M-mode position as LVEDD. Right side of septum to left side.

Normal:0.6–1.0 cm (women); 0.6–1.0 cm (men); > 1.2 cm = hypertrophy

Tip:Measure at end-diastole. Asymmetric hypertrophy (IVS/PW ratio > 1.3) suggests HCM.

Posterior Wall (PW) Thickness

Where:Diastolic thickness of the posterior LV wall, from the endocardial to epicardial surface.

Normal:0.6–1.0 cm; > 1.2 cm = hypertrophy

Tip:Measured at the same level as IVS (mitral valve tips). Increases with hypertension, HCM, amyloid.

Aortic Root / LVOT Diameter

Where:Aortic root: sinus of Valsalva to sinus of Valsalva at end-diastole, inner edge to inner edge.

Normal:Aortic root ≤ 3.7 cm (men) / ≤ 3.6 cm (women); LVOT ≈ 1.8–2.2 cm

Tip:Used to calculate stroke volume (SV = LVOT area × VTI from PSAX or A5C). Aortic root > 4.5 cm warrants referral.

Pericardial Effusion

Where:Largest echo-free space between pericardium and myocardium. Measure in diastole, in the view where effusion is largest.

Normal:< 0.5 cm = trivial; 0.5–1.0 cm = small; 1.0–2.0 cm = moderate; > 2.0 cm = large

Tip:PLAX is most sensitive. Confirm in PSAX and apical views. Circumferential vs. loculated. Tamponade: RV free wall collapse in diastole.

Probe at 3rd–4th ICS, left sternal border. Rotate counterclockwise to align with cardiac axis.

Pericardial effusionReduced EF (EPSS >1cm)Aortic dilationPosterior effusion

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