Audience: echocardiographers, cardiology trainees and clinicians interpreting cardiac ultrasound. Evidence reviewed: September 2026.

Key message

An echocardiographic image is a physical measurement, not a photograph. Diagnostic confidence depends on understanding how pulse frequency, propagation, beam geometry, signal processing and Doppler assumptions shape what appears on screen.

Learning objectives

• Relate frequency, wavelength and propagation speed to image quality.
• Distinguish axial, lateral and elevational resolution.
• Choose pulse-repetition frequency, scale, gain and filters intelligently.
• Recognise common artefacts before they become diagnostic errors.

How the pulse becomes an image

Piezoelectric elements convert electrical energy into ultrasound and returning mechanical energy into voltage. In soft tissue, scanners assume a propagation speed of approximately 1540 m/s. Depth is estimated from round-trip travel time. Because this speed is assumed rather than measured in each tissue, speed error can misplace structures.

Wavelength equals propagation speed divided by frequency. Higher-frequency imaging shortens wavelength and generally improves resolution, but attenuation rises and penetration falls. Adult transthoracic studies therefore require a compromise: use the highest frequency that still visualises the structure of interest.

Resolution is directional

Doppler: measure the component along the beam

The Doppler shift depends on transmitted frequency, blood velocity and the cosine of the insonation angle. Alignment matters: an angle error causes velocity underestimation and the error is amplified when velocity is squared in the simplified Bernoulli equation, ΔP = 4v².

Pulsed-wave Doppler provides range specificity but aliases when the Doppler shift exceeds the Nyquist limit, equal to half the pulse-repetition frequency. Continuous-wave Doppler measures high velocities without aliasing but cannot assign them to a unique depth. Colour Doppler displays mean velocity and variance within each sample region; it is a mapping tool, not a direct measure of regurgitant severity.

Controls that change the answer

• Overall gain and time-gain compensation: optimise signal without manufacturing tissue or erasing weak boundaries.
• Depth and sector width: keep only the anatomy needed to improve frame rate.
• Focus: place at or just below the structure of interest.
• Velocity scale and baseline: adjust to the expected flow; a low colour scale increases sensitivity but also blooming.
• Wall filter: suppresses low-frequency tissue motion but can remove genuine low-velocity flow.
• Dynamic range: changes contrast; excessive compression can conceal subtle boundaries.

Artefacts worth naming

Reverberation creates repeated interfaces; acoustic shadowing follows strongly attenuating structures; mirror artefact duplicates anatomy across a strong reflector; side lobes and grating lobes place off-axis reflectors in the main beam; refraction may duplicate or laterally displace anatomy. Confirm a suspected mass, defect or dissection plane in orthogonal views and with altered transducer position and settings.

A disciplined optimisation sequence

Begin with the clinical question. Select the window and frequency, minimise depth and sector width, position the focus, then adjust gain and compression. For Doppler, align the beam, choose the correct modality, optimise scale and sweep speed, and record several representative beats—more when rhythm or respiration varies. Measurements should follow current chamber and valve standards rather than a visually attractive but non-standard view.

Selected references

• ASE: comprehensive adult transthoracic echocardiography guideline.
• British Society of Echocardiography protocols and guidelines.
• ASE/EACVI chamber-quantification recommendations.

Educational material only. Apply local protocols, equipment-specific guidance and specialist review to individual patients.

Audience: cardiology trainees, sonographers and clinicians interpreting adult echocardiography.
Evidence reviewed: 19 September 2026.

Key message: echocardiography estimates the probability and consequences of pulmonary hypertension (PH). It does not establish PH from a single pulmonary artery systolic pressure cut-off. Right-heart catheterisation (RHC) remains the reference method when haemodynamic confirmation will affect management.

Learning objectives

• Acquire and interpret peak tricuspid-regurgitation velocity correctly.
• Combine TR velocity with supporting signs from the ventricles, pulmonary artery and IVC/right atrium.
• Estimate RV systolic pressure while recognising major sources of error.
• Report RV adaptation and likely aetiology, not pressure alone.

Start with the invasive definition

The 2022 ESC/ERS definition of PH is a resting mean pulmonary artery pressure above 20 mmHg measured at RHC. Classification additionally requires pulmonary arterial wedge pressure and pulmonary vascular resistance. An echo-derived PASP cannot replace these measurements.

1. Measure peak TR velocity

Use continuous-wave Doppler from multiple windows, including the RV-focused apical four-chamber, parasternal RV inflow, parasternal short-axis and subcostal views where useful. Record the highest complete, well-aligned envelope. Do not trace artefact, excessive spectral broadening, an incomplete envelope or a post-ectopic beat.

In sinus rhythm, use representative beats. In atrial fibrillation or marked beat-to-beat variation, average five to seven suitable beats acquired under comparable loading conditions. A weak or absent TR signal does not exclude PH.

2. Determine echocardiographic probability

The BSE probability algorithm uses peak TR velocity as its first branch. A peak velocity above 3.4 m/s supports high probability. A velocity at or below 2.8 m/s supports low probability only when additional PH signs are absent. Intermediate values require supporting evidence. The 2025 ASE guideline similarly emphasises an integrated approach rather than fixed PASP severity bands.

Use findings from more than one domain. No single adjunctive sign is diagnostic in isolation.

3. Estimate RV systolic pressure carefully

When there is no RVOT or pulmonary-valve obstruction:

RVSP = 4 × (peak TR velocity)² + estimated right-atrial pressure

If peak TR velocity is 3.0 m/s and estimated RAP is 15 mmHg, RVSP is 4 × 9 + 15 = 51 mmHg. Report this as an estimate. Do not label PH mild, moderate or severe from fixed PASP bands.

RAP estimation is less reliable with positive-pressure ventilation, raised intra-abdominal pressure, pregnancy, athletic remodelling, severe TR and poor subcostal imaging.

Important pitfalls

• Underestimation: poor alignment, incomplete envelope, weak TR, advanced RV failure, severe free-flowing TR or early RV–RA pressure equalisation.
• Overestimation: tracing noise, excessive gain, spectral broadening, a post-ectopic beat or an incorrect RAP estimate.
• RVSP approximates PASP only when there is no obstruction between the RV and pulmonary artery.
• An ultrasound-enhancing agent may improve a weak envelope, but overgaining creates a falsely traceable signal.

Assess the RV and seek the cause

Report RV geometry, basal diameter, wall thickness where relevant, TAPSE, lateral S′, FAC, RV free-wall strain when available, RA size, TR mechanism/severity and pericardial effusion. Consider left-heart disease, valve disease, congenital shunt, lung disease/hypoxia, chronic thromboembolic disease, pulmonary arterial hypertension and mixed causes.

Suggested report

Peak TR velocity is 3.2 m/s. RV dilatation, systolic septal flattening and a dilated IVC with reduced inspiratory collapse indicate a high echocardiographic probability of pulmonary hypertension. RV systolic function is reduced by FAC and RV free-wall strain. Clinical correlation and specialist assessment are advised. Consider RHC if confirmation and haemodynamic classification will alter management.

References

1. Mukherjee M, et al. ASE right-heart and PH guideline. JASE. 2025;38:141–186.
2. Humbert M, et al. 2022 ESC/ERS PH guideline. Eur Heart J. 2022;43:3618–3731.
3. Augustine DX, et al. BSE PH protocol. Echo Res Pract. 2018;5:G11–G24.
4. Zaidi A, et al. BSE right-heart guideline. Echo Res Pract. 2020;7:G19–G41.

Educational content for clinicians. It does not replace patient-specific assessment, local protocols or specialist advice.