Cardiac — Apical 4-Chamber (A4C)

Learning objectives

• Obtain an apical 4-chamber view from the point of maximal impulse.
• Identify all four chambers and the atrioventricular valves.
• Compare RV:LV size and recognize acute RV strain.

Maps to

• Resident: ACEP Emergency Ultrasound — Cardiac: Apical acquisition
• Resident: ACEP Emergency Ultrasound — Cardiac: RV assessment
• Tech: ARDMS Adult Echocardiography (AE) — apical views

Acquisition — getting the view

Probe

phased-array

Patient position

Left lateral decubitus improves the apical window.

Orientation convention

cardiology

Probe placement

Cardiac apex — below the left nipple / point of maximal impulse

Marker direction

Indicator to the patient's left (~3 o'clock), beam toward the right shoulder

Probe placement (3D)

Structures in the imaging plane (near → far): Chest wall · Left ventricle (apex nearest) · Right ventricle · Mitral valve · Tricuspid valve · Left atrium · Right atrium

Step by step

1. From left lateral decubitus, place the probe at the PMI, indicator to the patient's left, and aim up the heart's long axis.
   Why: Aligns the beam from apex to base for a true 4-chamber plane.
2. Adjust until both AV valves and all four chambers appear, LV apex at the top.
   Why: Foreshortening hides the true apex and distorts volumes.
3. Compare the RV and LV cavity sizes at end-diastole.
   Why: RV:LV ratio is the key screen for acute right-heart strain.

Troubleshooting

Foreshortened ventricle.

Move down an interspace and aim more cephalad to capture the true apex.

Poor apical window.

Roll further into left lateral decubitus and scan during held expiration.

Findings: normal

Normal A4C

RV smaller than LV (RV:LV < 0.6), both contracting well, with thin mobile AV valves.

Original schematic, dedicated to the public domain (CC0).

Findings: pathology

Acute RV strain

An enlarged RV approaching or exceeding LV size (RV:LV ≥ 1) suggests acute strain, as in massive pulmonary embolism.

Signs: RV:LV ≥ 1; RV dilation with poor function

Original schematic, dedicated to the public domain (CC0).

Interpretation practice

On A4C the right ventricle is as large as the left ventricle in a dyspneic, hypotensive patient. What does this suggest?

Original schematic, dedicated to the public domain (CC0).

Normal heartAcute RV strain (e.g., massive PE)Left heart failurePericardial effusion

Check your understanding

References

• ACEP SonoGuide — Echocardiography for Emergency Physicians · ACEP

Related modules

• Cardiac — Parasternal Long Axis (PLAX)
• Cardiac — Subxiphoid (Subcostal) 4-Chamber
• eFAST — Right Upper Quadrant (Morison's Pouch)
• eFAST — Suprapubic (Pelvic)
• Abdominal Aorta (AAA Screening)
• Lung — Anterior (BLUE Protocol)