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← Cardiology indexChapter sections
Purpose and principlesIndications, selection and cautionsMethod and interpretationClinical next stepsRisks, monitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Chest radiography in cardiovascular disease

Cardiology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
!
Time-critical presentation

Do not delay reperfusion, CT aortography or treatment of pulmonary oedema for a chest radiograph when the clinical diagnosis already demands urgent action.

Purpose and principles

Use the chest radiograph as a targeted assessment of cardiac size, pulmonary circulation, devices and alternative thoracic disease without over-reading a normal film.

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.

Indications, selection and cautions

Pulmonary oedemaRed flag

Bilateral perihilar or diffuse air-space opacity, vascular indistinctness, septal lines and effusions support congestion; correlate with rapidity and volume status.

Cardiomegaly

A cardiothoracic ratio above 0.5 on an adequate PA film suggests enlargement but cannot identify the chamber or distinguish myocardium from pericardial fluid.

Aortic concernRed flag

Mediastinal widening, abnormal aortic contour, apical cap or displaced calcification can raise suspicion but a normal film does not exclude dissection.

Pericardial effusion clue

A rapidly enlarging globular silhouette may occur with a large effusion; echocardiography determines haemodynamic effect.

Device complicationRed flag

New lead discontinuity, displacement, pneumothorax, haemothorax or generator change after implantation requires prompt device and clinical review.

Method and interpretation

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 05
    Natriuretic peptide and renal function
    Why
    Support heart-failure assessment and guide further imaging.

Clinical next steps

01Preferred routeSuspected heart failureFirst stepPreferredDyspnoea, oedema or signs of congestion+
  1. 1Assess severity and treat hypoxaemia or pulmonary oedema immediately when present.
  2. 2Obtain ECG, natriuretic peptide, renal function and chest radiograph as clinically appropriate.
  3. 3AlternativeUse the film to identify congestion and alternative lung disease, not to measure ejection fraction.
  4. 4Arrange echocardiography under the heart-failure pathway; urgency follows natriuretic-peptide level and clinical condition.
02AlternativePost-device filmAlternativeRecent pacemaker, ICD or central-line procedure+

Risks, monitoring and follow-up

  • 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.

Special situations

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.

Common pitfalls

  1. 01

    Calculating a cardiothoracic ratio on a rotated AP portable film.

  2. 02

    Excluding acute heart failure because the heart is not enlarged.

  3. 03

    Reassuring a patient with suspected dissection because the mediastinum is not widened.

  4. 04

    Reporting lead position without checking pneumothorax and electrical function.

  5. 05

    Attributing every bilateral opacity to cardiogenic oedema without considering infection, haemorrhage or ARDS.

Practice

Two practice questions

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Question 1 of 2
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CardiologyOriginal SBA

Apparent cardiomegaly

A supine AP portable film appears to show an enlarged cardiac silhouette. What is the most appropriate interpretation?

Choose one answer, then submit
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE NG106: Chronic heart failure in adults
  • NICE CG95: Recent-onset chest pain
  • ESC 2024 Guidelines for chronic coronary syndromes
  • ESC 2024 Guidelines for peripheral arterial and aortic diseases

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
Interpretation and limitations
Interpret natriuretic peptide with rhythm, age, obesity and renal function; it is not replaced by radiographic congestion.
1
Confirm 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+
    1. 1Begin urgent clinical risk assessment, monitoring, analgesia and senior involvement.
    2. 2Do not use a normal chest radiograph to rule out the diagnosis.
    3. 3DefinitiveProceed to definitive aortic imaging selected for stability and contraindications.
    4. 4Engage the aortic or cardiothoracic service immediately when imaging confirms disease.