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EASy MAPSubcostal 4-Chamber
View 1 · probe position A · the cardiac window
Machine setup
- Sector (phased-array / cardiac) probe — the same probe for all six views.
- Adult Cardiac preset, B-mode.
- Marker indicator on the upper right of the screen (cardiology convention).
- Depth 21 cm.
- Frequency at the probe's lowest setting (typically 2 MHz).
- TGC on; increase far gain to fill in the far field.
Acquire
- Gel the transducer. Patient supine if tolerated and practical.
- Place the probe 2 cm inferior to the xiphoid process, marker toward the patient's left (3 o'clock), overhand grip.
- Trap a small skin fold under the probe; significant inward pressure is often needed. Attend to comfort in awake or lightly sedated patients.
- Angle the probe tail caudally and toward the patient's right, coming slightly out of the axial plane — this aims the beam cephalad and toward the patient's left.
- A segment of liver should appear in the superficial image: the left lobe is the acoustic window that carries the beam to the heart.
Pitfalls
- Not enough gel, or not enough probe pressure — the commonest cause of a poor novice image.
- Gripping the probe too far from the emitter, or too tightly, kills fine control.
- Subcostal alone can underestimate RV size and miss the cardiac midsegment and apex.
- In very low-flow states or on mechanical support, swirling heterogeneous echogenicity in the ventricles is stasis, not a gain problem.
- A poor-quality cardiac view (≤ 6) is not usable for cardiac decisions — the IVC, lung and pleural findings may still be actionable.
Optimize
- At 21 cm the sector should already extend slightly beyond the posterior LV wall, so the whole pericardium is included — if the heart still doesn't fit, add depth.
- Set gain so blood filling the chambers is black; some visible turbulent flow is acceptable.
- Off-axis chambers → rotate counterclockwise. Chambers cut off or off-centre → rock right or left.
- LVOT in view → you are in a 5-chamber plane; lift the tail to drop it out.
Confirm before you record
A correctly acquired view shows both ventricles, both atria, and the tricuspid and mitral valves — but not the left ventricular outflow tract. Record a 4 s clip (longer if the ventricular rate is < 30 bpm).
Read it in this order
- Pericardium — non-trivial effusion (> 10 mm, through systole and diastole). Tamponade is a clinical diagnosis, supported by atrial collapse in systole or ventricular collapse in diastole.
- RV size and function — an RV larger than the LV (RV/LV > 1) is severe dilation; look for a diastolic free wall > 1 cm or an enlarged RA as signs of chronicity.
- Septum — thinning, rupture, hypertrophy; shift toward the LV if the RV is dilated.
- LV size and function — severe dilation, marked wall thickening, or minimal systolic cavity reduction with poor mitral annular motion.
- Then integrate with the IVC, the lung profile and the clinical picture — not before.
12-point quality score
| Score each 0–2 | Total |
|---|---|
| Pericardium · RV size · RV function | 10–12 good |
| Septum · LV size · LV function | 7–9 adequate |
| 0 = not assessable, 1 = usable, 2 = clear | ≤ 6 poor |