A Complete Guide to Learning 2D Echocardiography

1. What is 2D Echocardiography?

2. Ultrasound Physics - The Foundation

Ultrasound Waves

• Sound waves with frequency >20,000 Hz (cardiac probes: 1-8 MHz)
• The fundamental equation: wavelength = speed / frequency (speed in tissue ~1540 m/s)
• Higher frequency = better resolution but less penetration
• Lower frequency = deeper penetration but less resolution

Tissue Interactions

The Transducer

• Contains piezoelectric crystals that convert electricity to sound and back
• Acts as both transmitter and receiver
• Pulse Repetition Frequency (PRF): how many pulses per second - limited by imaging depth

3. Image Production - How the 2D Picture is Made

1. A short ultrasound pulse is fired along each scan line
2. Reflected signals return to the transducer, with:
   • Amplitude proportional to angle of incidence and acoustic impedance difference
   • Timing proportional to distance from transducer (depth = time x speed/2)
3. Signals undergo amplification, time-gain compensation (TGC), and gray-scale mapping
4. All lines are assembled into one image frame

• More scan lines = better image density but slower frame rate
• Standard: ≥30 frames/second for cardiac motion (128 scan lines at 20 cm depth)
• Cardiac imaging needs high frame rate - do not sacrifice it for width

Key Instrument Controls

4. M-Mode vs. 2D vs. 3D

5. Acoustic Windows - Where You Put the Probe

6. The Standard Views - Systematic 2D Echo Exam

Parasternal Long-Axis (PLAX)

• Position: Left 3rd-4th intercostal space, adjacent to sternum; patient in left lateral decubitus
• What you see: Aortic valve, mitral valve, LV (basal/mid), LA, proximal ascending aorta, RV outflow tract, pericardium
• Structures NOT seen: Apical LV segments, RV apex
• Key measurements: LV wall thickness, LV internal dimension, aortic root diameter, LA diameter

Parasternal Short-Axis (PSAX)

• Rotate probe 90° clockwise from PLAX
• Sweep from base to apex to visualize different levels:
  • Aortic valve level - "Mercedes-Benz" aortic valve, LA, RA, RV, pulmonary valve, MPA
  • Mitral valve level - "Fish-mouth" MV opening, LV as circle
  • Papillary muscle level - Medial and lateral papillary muscles, LV wall segments
  • Apical level - LV tapers to a point

Apical Four-Chamber View (A4C)

• Position: Directly over the LV apex; patient in steep left lateral decubitus
• What you see: All 4 chambers simultaneously, both AV valves, interatrial septum, interventricular septum
• Key uses: LV/RV size and function, mitral/tricuspid valve disease, LV wall motion
• Pitfall: Foreshortening - if the LV looks too spherical, move medially until the true apex is seen

Apical Two-Chamber View (A2C)

• Rotate probe ~60° counterclockwise from A4C
• What you see: LV only (anterior and inferior walls), LA, mitral valve
• Used together with A4C for biplane LV volumes (Simpson's method)

Apical Long-Axis View (A-LAX / Apical 3-Chamber)

• Rotate another ~60° counterclockwise from A2C
• What you see: Aortic valve, mitral valve, LV (inferoseptum and anterolateral wall), LA, aortic root
• Equivalent plane to PLAX but from the apex - confirms PLAX findings

Subcostal Views

• Subcostal 4-chamber: Excellent for IAS (best view for detecting ASD), when parasternal/apical windows are poor (COPD, post-surgery)
• Subcostal short-axis: RV, aortic valve, pulmonary valve, IAS
• IVC view: Assess IVC diameter and collapsibility (used to estimate right atrial pressure)

Suprasternal Notch

• Aortic arch anatomy, coarctation assessment, descending aorta Doppler

7. Best Views for Each Structure

8. Imaging Artifacts - Don't Be Fooled

9. What to Assess Systematically on Every Echo

1. LV size and function - chamber dimensions, wall thickness, regional wall motion, ejection fraction
2. RV size and function - RV/LV ratio, wall motion, TAPSE
3. LA and RA size - chamber dimensions
4. Aortic valve - leaflet number, thickening/calcification, opening, any stenosis/regurgitation signs
5. Mitral valve - leaflet morphology, motion, prolapse, rheumatic changes
6. Tricuspid and pulmonary valves
7. Pericardium - effusion (size, location), tamponade signs (RA/RV collapse)
8. Aorta - root and ascending diameter, arch
9. IVC - diameter and respiratory variation (RA pressure estimation)

10. Key Measurements (Normal Values)

11. How to Learn - Practical Pathway

Resources

• Textbook of Clinical Echocardiography by Catherine M. Otto (Elsevier) - the gold standard reference used above
• American Society of Echocardiography (ASE) guidelines: aseuniversity.org - free online guidelines with images
• EchoFirst app and online simulators for self-study of views

• PW Doppler: Range-specific, low velocities - mitral inflow, LVOT VTI, pulmonary veins. Max ~1 m/s at 6 cm
• CW Doppler: No range limit, high velocities - aortic stenosis, TR jet for PASP, MR for dP/dt. Uses ΔP = 4V²
• Color Doppler: Shows WHERE flow is going, screens for regurgitation, guides CW beam alignment
• Tissue Doppler: Measures myocardial motion at the annulus - e', s', a' - key for diastolic function (E/e' ratio)