01Purpose and principlesWhat the assessment is for and the core concepts behind it.
Chest radiography provides context rather than a haemodynamic measurement. Projection and patient position can change apparent cardiac size, vascular distribution and effusion layering.
Read systematically: technical quality, airway and mediastinum, cardiac silhouette, hila and vessels, lungs and pleura, then bones, soft tissues and devices.
Integrate the film with examination, natriuretic peptide, ECG and echocardiography; discordance should prompt reconsideration rather than forced pattern matching.
Key points
- Confirm patient, date, projection, rotation, inspiration and exposure before interpreting the heart or mediastinum.
- Cardiothoracic ratio is meaningful on a well-inspired PA film; AP portable magnification can mimic cardiomegaly.
- Upper-lobe venous diversion, interstitial markings, septal lines, perihilar air-space opacity and pleural effusions form a congestion spectrum.
- Acute pulmonary oedema can occur with a normal-sized heart, and an early film may be normal.
- A widened mediastinum is neither sensitive nor specific for acute aortic syndrome; definitive aortic imaging is required when suspected.
- Check device generator, lead course, tip position, integrity and complications against prior films.
- Always inspect lungs, pleura, bones and soft tissues for non-cardiac explanations of symptoms.
02Indications, selection and cautionsWhen it is useful, when urgency changes and important limitations.
Bilateral perihilar or diffuse air-space opacity, vascular indistinctness, septal lines and effusions support congestion; correlate with rapidity and volume status.
A cardiothoracic ratio above 0.5 on an adequate PA film suggests enlargement but cannot identify the chamber or distinguish myocardium from pericardial fluid.
Mediastinal widening, abnormal aortic contour, apical cap or displaced calcification can raise suspicion but a normal film does not exclude dissection.
A rapidly enlarging globular silhouette may occur with a large effusion; echocardiography determines haemodynamic effect.
New lead discontinuity, displacement, pneumothorax, haemothorax or generator change after implantation requires prompt device and clinical review.
03Method and interpretationA systematic approach to the test and its findings.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
PA and lateral chest radiographsFirst step - Why
- Assess heart size, pulmonary vasculature, pleura and thoracic alternatives in a stable ambulant patient.
- Interpretation and limitations
- PA projection reduces cardiac magnification; compare with prior films and clinical volume status.
- 02
Portable AP chest radiograph - Why
- Rapid assessment in an unwell or immobile patient and line or device position.
- Interpretation and limitations
- Expect magnification, low inspiration and supine redistribution; avoid diagnosing cardiomegaly from ratio alone.
- 03
Transthoracic echocardiography - Why
- Clarify ventricular function, valve disease or pericardial fluid suggested by the film.
- Interpretation and limitations
- Echo answers structural and haemodynamic questions that radiography cannot.
- 04
CT aortography - Why
- Evaluate suspected acute aortic syndrome in a suitable patient.
- Interpretation and limitations
- Use the emergency aortic protocol; chest-radiograph appearance should not be a gatekeeper.
- 05
Natriuretic peptide and renal function - Why
- Support heart-failure assessment and guide further imaging.
- Interpretation and limitations
- Interpret natriuretic peptide with rhythm, age, obesity and renal function; it is not replaced by radiographic congestion.
04Clinical next stepsHow the result changes management or prompts escalation.
01Preferred routeSuspected heart failureFirst stepPreferredDyspnoea, oedema or signs of congestion+
- 1Assess severity and treat hypoxaemia or pulmonary oedema immediately when present.
- 2Obtain ECG, natriuretic peptide, renal function and chest radiograph as clinically appropriate.
- 3AlternativeUse the film to identify congestion and alternative lung disease, not to measure ejection fraction.
- 4Arrange echocardiography under the heart-failure pathway; urgency follows natriuretic-peptide level and clinical condition.
02AlternativePost-device filmAlternativeRecent pacemaker, ICD or central-line procedure+
- 1Confirm projection and compare lead or line position with the procedural record and prior image.
- 2Inspect both apices and pleural spaces for pneumothorax or haemothorax.
- 3Check electrical parameters separately because a normal film does not prove correct function.
- 4EscalationEscalate displacement, lead damage or a new pleural complication to the implanting team.
03EscalationPossible acute aortic syndromeEscalationAbrupt severe pain or examination red flags with or without abnormal radiography+
- 1Begin urgent clinical risk assessment, monitoring, analgesia and senior involvement.
- 2Do not use a normal chest radiograph to rule out the diagnosis.
- 3DefinitiveProceed to definitive aortic imaging selected for stability and contraindications.
- 4Engage the aortic or cardiothoracic service immediately when imaging confirms disease.
05Risks, monitoring and follow-upComplications, safety checks and further assessment.
- Compare serial films only after accounting for projection and position.
- Trend oxygen requirement, respiratory rate, weight, fluid balance and renal function when congestion is treated.
- Document device model and prior lead positions for future comparison.
- Ensure urgent or unexpected findings are directly communicated and acknowledged.
- Review whether follow-on echo, CT or specialist assessment actually occurred.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
Projection changes the diagnosis
Portable AP imaging enlarges the cardiac silhouette and can falsely suggest cardiomegaly.
Distribution follows gravity
Supine oedema and effusions may look diffuse or posterior rather than forming classic upright patterns.
Kerley B lines
Short peripheral basal lines reflect interlobular septal thickening but are not unique to cardiac failure.
Echo follows silhouette
A globular heart cannot distinguish dilatation from effusion; echocardiography is the discriminating test.
Check behind the heart
Retrocardiac consolidation and hiatus hernia can be missed when attention stops at the cardiac border.
07Common pitfallsFrequent interpretation and management errors.
- 01
Calculating a cardiothoracic ratio on a rotated AP portable film.
- 02
Excluding acute heart failure because the heart is not enlarged.
- 03
Reassuring a patient with suspected dissection because the mediastinum is not widened.
- 04
Reporting lead position without checking pneumothorax and electrical function.
- 05
Attributing every bilateral opacity to cardiogenic oedema without considering infection, haemorrhage or ARDS.