CXR in Heart disease: Part 1
Introduction
Despite advances in various imaging modalities, the chest radiograph remains an important initial diagnostic tool in cardiac patients. Interpreting a chest radiograph involves checking the side markers, determining the projection(PA, AP or supine), assessing technical adequacy of the film(exposure, rotation, inspiratory or expiratory), identify and assess position of medical devices, categorising detected abnormalities, reviewing previous films and suspecting cardiac disease based on preformed criteria’s. This article provides a guide to the systematic interpretation of a chest radiograph and a review of the classic radiological signs of cardiac disease
Outline of the Article |
A. Differentiation between Inspiratory vs Expiratory Film/Structures seen in PA and Lateral view |
B. Diagnosis of chamber enlargement |
C. Diagnosis of PAH, PVH and vascularity |
D. Diagnosis of cardiomyopathy and Pericardial diseases |
E. Diagnosis of Pulmonary and Aortic diseases |
F. X ray in congenital heart diseases |
- Differentiation between Inspiratory and Expiratory film and Structures seen in AP and Lateral view
PA view | AP view |
In erect patients | In supine patients |
Vertebral spines more | Vertebral bodies clear |
Scapulae clear of lungs | Scapulae overlap |
Clavicles are horizontal | Clavicles are oblique |
Gas bubble in fundus with a | Gas bubble in antrum |
No apparent cardiomegaly | Apparent cardiomegaly |
Overriding of clavicle and first rib | Not prominent |
Clavicle companion shadow | Absent |
- Assessment of Cardiomegaly and Chamber enlargement
- Assessment of cardiomegaly
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Normally less than 0.55 |
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>0.55 in Adults – Cardiomegaly |
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>0.60 in Newborns – Cardiomegaly |
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Any increase in transcardiac diameter > 2 cm compared to old x-ray |
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In old age and emphysema a transcardiac diameter more than 15.5 cm in males &>12.5 cm in females |
Clinical Vignette: Spurious causes of cardiac enlargement
- Portable Film
- Obesity
- Pectus excavatum
- Straight back syndrome
- Ascites
- Poor Inspiration
- Large epicardial pad of fat
- Absence of Pericardium
Clinical Vignette: Causes of Micro cardia
- Normal variant
- Severe malnutrition and dehydration
- Addison’s disease
- Emphysema
- Constrictive pericarditis
- Assessment of Right atrial enlargement
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Vertical Criteria |
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(i). Rt. Atrial border extends >3 intercostal spaces |
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(ii). Rt. Atrial border more than 50 percent of right heart border |
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Horizontal Criteria |
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(i). Rt. Atrial border extending 3.5 cm beyond lateral vertebral border |
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(ii). Rt. Atrial border extending 5.5 cm beyond mid vertebral line |
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(iii). Right Atrium occupying more than one third of right hemithorax |
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(iv). right atrial convexity is more than 50% of the cardiovascular height |
- Assessment of Left atrial enlargement
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(i). Widening of carina (normal 45-75 degree) |
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(ii). Elevation of left bronchus |
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(iii). Straightening of left border |
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(iv). Double atrial shadow (shadow within shadow) |
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Grade 1 –double cardiac contour |
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Grade2 – LA touches RA border |
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Grade 3 – LA overshoots the Rt. Cardiac border (atrial escape sign) |
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(v). Displaces the descending aorta to the left and esophagus to right seen in barium swallow |
- Assessment of right ventricular enlargement
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(i) PA view |
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1. Cardiophrenic angle is acute. |
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2. Clockwise rotation of heart causes RV to form the middle portion of the left heart border |
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(ii) RIGHT LATERAL VIEW |
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1. Obliteration of retrosternal space |
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(iii) LEFT LATERAL VIEW |
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• Rigler’s measurement will be 17mm or less |
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• Rigler’s measurement will be 7.5mm or more |
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• Eyeler’s ratio is 0.42 or less |
- Assessment of left ventricular enlargement
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PA view |
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(a)Left cardiac border gets enlarged and becomes more convex |
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(b)Lt. cardiac border dips into lt. dome of diaphragm |
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(c) rounded apical segment |
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(d) cardiophrenic angle is obtuse |
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Lateral view |
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(a) Left ventricle enlarges inferiorly and posteriorly |
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(b) Rigler’s measurement A is >17 mm |
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(c) Rigler’s measurement B is< 7.5 mm |
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(d) Eyeler’s ratio becomes > 0.42 |
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LA Oblique view Mild lt. Ventricular enlargement-obliteration of retrocardiac space |
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Mod. Lt.ventricular enlargement-cardiac shadow overlaps vertebral column |
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Marked Lt.ventricular enlargement-cardiac shadow overshoots vertebral column |
Clinical Vignette: Differential Diagnosis of Retrosternal filling on Lateral CXR
- RV dilatation
- TGA
- Ascending aortic aneurysm
- Non cardiovascular masses like lymphoma and thymoma
- Assessment of pulmonary artery and venous hypertension and vascularity
- Assessment of pulmonary artery hypertension
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• Prominent Main pulmonary Artery |
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• Right descending pulmonary artery |
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> 17 mm in males and > 16 mm in females. |
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• Pruning of peripheral pulmonary artery. |
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• Reduced retro-sternal space on lateral views due to RV dilatation |
Clinical Vignette
- Echo criteria for dilated pulmonary artery > 22 mm
- CT criteria for dilated pulmonary artery > 26 mm
- Assessment of Pulmonary venous hypertension
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LARRY ELLIOT’S CLASSIFICATION OF PVH |
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Radiographic grade of PVH |
Acute Disease PCWP(mm Hg) |
Chronic disease PCWP(mm Hg) |
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Grade 1 |
13-17 |
13-17 |
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Grade 2 |
18-25 |
18-30 |
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Grade 3 |
>25 |
>30 |
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Grade 4 |
Hemosiderosis and ossification |
Long standing PVH |
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GRADE 0 -PCWP<12 MM HG Upper lobe pulmonary veins are less prominent than lower lobe veins |
GRADE 1- PCWP 13-17MMHG Redistribution of blood flow with cephalization’ ‘ANTLER SIGN’ 1. increased resistance to flow due to interstitial odema 2. alveolar hypoxia in lower lobes causes reflex vasoconstriction 3. vasoconstriction of the arterioles due to LA or pulmonary vein reflex |
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GRADE 2-PCWP 18–25 mm Hg 1. Interstitial edema 2. Peribronchial cuffing 3. Kerley A,B,C lines
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GRADE 3 – PCWP> 25mm hg 1. Alveolar odema
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Kerley A lines |
Kerley B lines |
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Distended lymphatic channels within edematous septa coursing from peripheral lymphatics to central hilar nodes Towards the hilum Less specific for Pulmonary venous hypertension |
Horizontal lines 1-3 mm thick Perpendicular to pleural surface Towards the costophrenic angle Accumulation of fluid in interlobular septa and lymphatics Highly specific for PVH |
- Assessment of Pulmonary plethora
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• Pulmonary vessels are dilated and tortuous extending farther into the peripheral one-thirds of the lungs |
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• Diameter of a pulmonary artery is greater than the accompanying bronchus |
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• Right descending pulmonary artery to tracheal diameter Ratio > 1 |
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• End-on’s > 3 in one lung field and >5 in both lung fields. |
- Assessment of pulmonary oligemia
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• Small pulmonary artery |
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• Empty pulmonary bay |
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• Pulmonary vessels small |
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• Lung hyper translucent |
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• Lateral view shows diminution of hilar vessels |
