Apical Chambers (4)

Orientation and Structure:
- Views include Interventricular Septum (IVS), Right Ventricle (RV), Aorta (Ao), Left Ventricle (LV), Left Atrium (LA), and Left Ventricular Outflow Tract (LVOT).
- Required for examinations: Must visualize the left ventricle apex through to aortic valve (AV), into ascending aorta.
Technical Details:
- S4-2 imaging system used at a frequency of 47 Hz, with 72% amplitude and a depth of 17 cm.
Image Tips:
  - Angle anteriorly from the Apical 4 Chamber (A4C) view.
  - Sometimes slight cranial-caudal (CC) rotation helps improve visualization.
  - Confirm opening and closing of AV leaflets; avoid immobile AV annulus imagery.

Imaging Protocol:
  - Starting Position: Rotate probe 60⁰ from A4C position until RV is not visible.
  - Use of Breathing Techniques:
    - Exploit respiratory variations for improved anterior wall visibility.
    - Instruct patient to hold breath out, then take a small sniff and hold it to help overcome rib interference.
  - Anatomical Features:
    - Characterized by long, lean left ventricle and the ability to visualize the Left Atrial Appendage (LAA).
    - Descending Aorta seen well in this orientation.

Optimization Process:
  - Assess the left atrium (LA) at its largest volume; measurement should reflect LA volume index.
  - Normal LA volume index: < 34 ml/m².
  - Measurements include yields such as LAESV (Left Atrial End-Systolic Volume).
  - Example Measurements:
    - LA volume: 44.73 ml.
    - LAESV Index: 25.27 ml/m².

Parameters for Evaluation:
- Indicators of LAE include LA volume indices exceeding normal values, e.g., 70.34 ml/m² with LAESV being 109.72 ml
- Importance of these metrics: Help assess potential cardiac dysfunction or pathology.

End-Diastolic Measurements:
- Trace using annulus-to-annulus calipers, while ignoring papillary muscles to assess LV (Left Ventricle) during its largest size.
- Utilize the chroma map to optimize visualization.
Comparative Technique for End-Systole:
- Keep the chroma map setting consistent while recording LV at its smallest volume, following similar tracing methods to those in End-Diastolic setting.

Orientation Details:
  - Similar to PLAX (Parasternal Long Axis) view, but probe rotated roughly 60⁰ counter-clockwise from A2C or 120⁰ from A4C.
  - AV and MV (Mitral Valve) leaflets should be clearly visible along with the endocardium at MV level.
  - Maintain a clear view of the LV focusing on apex to assess wall motion and overall cardiac functionality.

Segment Definition:
- LV wall segments classified as Basic Apex Level, Mid Level, and Base Level.
- Mid-level division marked by the papillary muscle.

Purpose of Reduced Depth View:
- Allow for enhanced visualization of anatomy and precise dimensions of the heart structures at critical phases of the cardiac cycle.
LA Volume Measurement Timing:
- Must be completed at end-diastole to obtain accurate volume metrics representing the highest volume state before contraction.
A2C Landmarks:
- Anatomical structures not visible that serve as helpful landmarks may include the descending aorta and various papillary muscles.

Palma, Richard. Echocardiographer’s Pocket Reference; Fifth Edition. 2020.
Mitchell et al, Guidelines for Performing a Comprehensive Transthoracic Echocardiographic Examination in Adults: Recommendations from the American Society of Echocardiography, 2018.

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