Radiographic approach to cardiac enlargement

Radiographic approach to cardiac enlargement by Dr. Neelam Maharjan

1. Radiographic approach to cardiac enlargement Dr. Neelam Maharjan FCPS Resident, Bir hospital,NAMS

2. Anatomy Heart is pyramidal in shape and lies obliquely in the anterior mediastinum immediately posterior to the sternum and closely related to the central portion of the diaphragm. The left atrium forms base or posterior part with four pulmonary veins draining into it. The right atrium forms the right border with superior venacava and inferior venacava draining into its upper and lower part. The apex and left border is formed by left ventricle. The right ventricle forms the anterior part. The inferior or diaphragmatic part is formed by both ventricles anteriorly and a small part of right atrium posteriorly.

3. The interatrial and interventricular septa are said to lie in the left anterior oblique plane The transverse axis of the pair of valves are said to lie in the right anterior oblique plane.

4. Pericardium Closed sac consisting of parietal and visceral layers that enclose a potential space which contains 20-25 ml of serous fluid. Covers the heart and great vessels. Superior and inferior venacava and the pulmonary veins are all enclosed within a single fold of pericardium,which contain a recess known as oblique sinus. The outflow from the heart through the aorta and pulmonary artery is enveloped separately and between the major inflow and outflow vessels,there is a transverse pericardial sinus.

5. Right atrium -Triangular and broad based atrial appendage with trabeculations . -Superior and inferior venacava drain into the smooth posterior part. -Coronary sinus drain into the posterior wall between the orifice of IVC and tricuspid valve. - Crista terminalis separates atrial appendage from smooth part. - Interatrial septum bears an oval depression in its lower part, fossa ovalis , surrounded by superior limbus .

6. Left atrium Smooth walled chamber which gives rise to a narrow based and anteriorly pointing finger-like left atrial appendages. Lies slightly higher than right atrium Receives opening of four pulmonary veins in its posterior wall.

7. Right ventricle Roughly triangular and flattened from front to back. Its lower half normally touches the sternum on lateral view. Wall measures 4-5 mm Interventricular septum curves towards the right ventricle due to high pressure of LV Its inflow and outflow tract is separated by muscular conus or infundibulum . The interior of right ventricle has irregular muscular elevations called trabeculae carneae .

8. The entrance to the RV is tricuspid valve:has three leaflets( anterior,inferior and septal ) each attached to papillary muscles of ventricles by chordae tendinae . Pulmonary valves has three semilunar cusps:right and left anterior and a posterior cusps.

9. Left ventricle Most muscular chamber, finely trabeculated , being circular in cross section Wall thickness of 1 cm in diastole Fills through mitral valve with two leaflets; anterior and posterior attached to papillary muscles of ventricle by chordae tendinae Outflow through aortic valve;three cusps:right and left posterior and anterior. Above each cusp is a localised dilatation,k /a sinuses of valsalva

10. Coronary arteries and veins

11. Right coronary artery -Arises from anterior sinus of valsalva , passes to right in between pulmonary trunk and right atrium to descend in the right AV groove as the marginal artery. -On inferior surface of the heart, it anastomoses with the left coronary artery in the region of the posterior interventricular groove.

12. Branches Conus artery to the pulmonary outflow tract Atrial and ventricular branches Branch to sinoatrial node Acute marginal artery,which run anteriorly to supply the right ventricle Branch to atrioventricular node Posterior interventricular artery, supplies the inferior surface of left ventricle and the posterior two-thirds of the interventricular system.

13. Left coronary artery Arises from the left posterior sinus of valsalva , passes behind and to the left of the pulmonary trunk to reach to left AV groove. Bifurcates into left circumflex artery which anastomose with the right coronary artery and the anterior descending artery which descends in the interventricular groove.

14. Branches Anterior descending artery Septal branches Diagonal branches that run over anterolateral wall of the left ventricle supplying it Left circumflex artery Obtuse marginal branches, which supply the lateral wall of the left ventricle Atrial branches

15. Coronary Veins

16. Techniques available for examination of the heart: 1)Plain chest radiography 2)Echocardiography 3)CT scanning 4)MRI scanning 5)Radionuclide imaging 6)Angiography

17. CHEST X-RAY commonest type of imaging examination of the heart. cardiac size and contour can be clearly demonstrated. evaluation of lung field: gives vital clues to cardiac function. demonstrates additional features related to cardiac disease which may include metallic or other implants, calcifications or bony anomalies.

18. Technical Factors Conventional PA film: Positioning High KVp technique FFD- 6 feets ( minimize cardiac enlargement) Centering – at T7 Short exposure time to reduce motion artifact of heart End inspiration

19. Cardiac Silhouette The image of the heart and great vessels on the chest radiograph is a two-dimensional display of dynamic three dimensional structures . The cardiovascular silhouette varies not only with the abnormality but also with body habitus , age, respiratory depth, cardiac cycle, and position of the patient

20. With good centring two thirds of the cardiac shadow lies to the left of midline and one-third to the right, although this is quite variable in normal subjects.

21. Cardiac shape Hyposthenics : long and narrow Hypersthenics : transverse Moderately built: oblique or globular in shape Infants: Transverse or globular

22. Cardiac Silhouette Cardiac contour PA view Right Heart Border Superior venacava Ascending aorta ( when tortous ) Right atrium inferior venacava Left heart Borders Aortic Knuckle Pulmonary Bay Left Atrial appendage Left ventricle

23. PA view demonstrating cardiac silhouette

24. Lateral Projection Anteriorly Right atrial appendage Right ventricle Posteriorly Left atrium Left ventricle

25. Right anterior oblique Anterior border from above downwards: transverse part of arch of aorta , pulmonary trunk, RV and LV Posterior border: LA above and RA below Diaphragmatic surface: IVC, RA and RV

26. Left anterior oblique anterior border from above downwards: innominate veins, SVC, ascending aorta, RA appendage and RV posterior border from above downward: small part of LA and LV

27. Heart Size on Chest Radiographs Assessment of Transverse cardiac diameter Females: 14.5 cm Males: 15.5 cm Transverse cardiothoracic ratio Normal : 50 % on a PA 55% in Asians and Africo-Carribeans 60 % on AP and in children

28. An increase in excess of 1.5 cm in the transverse diameter on comparable serial films is significant. However, heart shadow is enlarged with: Short FFD On expiration In supine AP projection when the diaphragms are elevated

29. The heart enlarges in two different haemodynamic situations diastolic volume overload excessive volume of blood during its filling phase pump failure.

30. Heart Disease according to cardiac enlargement No cardiomegaly ( CT<0.5) Aortic Stenosis Arterial hypertension Mitral Stenosis Acute Myocardial Infarction Hypertrophic cardiomyopathy Restrictive cardiomyopathy Constrictive pericarditis With cardiomegaly (CT>0.5) Aortic regurgitation Mitral regurgitation Tricuspid regurgitation High output states Congetive cardiomyopathy Ischemic cardiomyopathy Pericardial effusion Paracardiac mass

31. Generalized Cardiac Enlargement Global heart enlargement, with maintenance of an otherwise normal cardiac contour, usually is due to diffuse myocardial disease, abnormal volume or pressure overload as a consequence of valvular heart disease , hyperthyroidism, hypothyroidism, and anemia . Pericardial effusions also produce generalized enlargement of the cardiac silhouette

32. Gross cardiomegaly Pericardial effusion Cardiomyopathy Multivalve disease Congenital heart disease notably Ebstein’s anomaly Ischemic heart disease

33. Left atrial enlargement Posterior chamber without any part forming silhouette of heart on PA view Forms the posterior superior silhouette of heart on lateral projection The chamber is the most posterior structure and abutts the left main bronchus and oseophagus posteriorly

34. Left atrium sits in middle of heart posteriorly Left atrium forms no border of normal heart in PA view LA RA LV This inset from a CT scan of the chest shows how RA and LV obscure LA from forming a heart border on the frontal film.

35. Left atrial enlargement Causes Volume loading – Mitral regurgitation, VSD, PDA Pressure loading –Left ventricular failure, Mitral stenosis , Mitral valve obstruction due to tumor

36. Causes of isolated left atrial enlargement: 1) Mitral valve stenosis caused by rheumatic heart disease. 2)Left atrial myxoma 3) Cor triatriatum Heart is normal sized with abnormal incorporation of Pulmonary venous structure in to the left atrium with unnecessary fibromuscular membranous sub-division through the atrial chamber => classic or cor triatriatum sinister (x ray changes similar to mitral stenosis ) similar in RA k/a cor triatriatum dexter

37. Radiographic features Elevation of left pulmonary artery Elevation and narrowing of left main bronchus Double right heart border: by projection of distended right ward margin of left atrium lying close to right atrial margin . {3 grades I to III: double border, flushes with RA border and overshoot RA and forms right heart border} The distance from the middle of the left atrial border on the double heart shadow to middle of left main bronchus more than 7cm

38. Convex left atrial appendage(third mogul sign):normally the left heart border just below the pulmonary outflow track should be flat or slightly concave.

39. Left atrial enlargement elevate the left main bronchus splaying of the carina straightening of the left heart border below the left main bronchus, then as a discrete bulge on the left Oesophageal indentation / displacement Left atrial shadow does not touch the right whereas vertical descent of right atrial touches the dome

40. Left atrial enlargement in combination with additional chamber involvement may be produced by various conditions, such as left ventricular failure, left-sided obstructive lesions, and certain shunts (e.g., ventricular septal defect, patent ductus arteriosus ,). However , left atrial enlargement is not seen with simple atrial septal defects . When left atrial enlargement is marked, it most often is due to rheumatic valvular disease

41. CT and MRI CT and MRI measurements of the left atrium rely on echocardiography data. Measurement is made at end ventricular systole when the left atrium is the maximum size Normal left atrial AP diameter Women<4 cm Men<4.1 cm AP measurement is made on the three chamber view on a gated cardiac CT

42. Atrial volume meaurements are considered more accurate then either an AP measurements or area measurements. Normal atrial volume Women : 53 ml Men : 59 ml Echocardiography data for left atrial enlargement slighly understimates the volume of the left atrium made by CT

43. Left ventricular enlargement Volume loading-AR,MR,PDA Pressure loading-HTN,AS Wall abnormalities-left ventricular aneurysm, cardiomyopathy

44. Signs on Xray Rounding of the apex of the heart Elongation of the long axis of the left ventricle - left and downwards In the lateral view, dilatation of the body of the left ventricular cavity is recognized when the shadow of the heart bulges behind the IVC

45. Obstruction to left ventricular emptying or increased afterload , as caused by systemic hypertension, aortic coarctation , or aortic valve stenosis , leads to hypertrophy initially, with rounding of the cardiac apex . Left ventricular dilatation with cardiac failure may follow. Dilated cardiomyopathy , especially ischemic cardiomyopathy , primarily enlarges the left ventricle.

46. Left Ventricle Left ventricle

47. Lateral view Left ventricle enlarges inferiorly and posteriorly (a)Hoffman Rigler’s measurement A is >17 mm (b) Eyeler’s ratio becomes > 0.42

48. Rigler’s measurement Rigler’s A & B used to differentiate left ventricular and right ventricular enlargement Possible only when IVC shadow present Jn. Of IVC with Lt. Atrium – J point Rigler’s A- from J point along line of IVC draw a line of 2 cm above and mark the point X.

49. Eyeler’s ratio Valid when IVC shadow is absent or cannot be visualised . Mark the point of joint where postero inferior cardiac border meets the dome as B From this point B draw a horizontal line to the posterior border of sternum-AB From point B - draw another horizontal line posteriorly to the inner border of the rib- B C Ratio of AB/BC is Eyeler’s ratio < 0.42

50. LV enlargement Rigler’s measurement A: >17 mm Rigler’s measurement B: <7.5 mm or obscured Eyeler’s ratio: >0.42 RV enlargement Rigler’s measurement A: 17 mm or less Rigler’s measurement B: 7.5 mm or more Eyeler’s ratio: 0.42 or less {Normal values} = in RV enlargement

51. Aortic valve regurgitation and mitral valve regurgitation enlarge the left ventricle and are associated with dilatation of the aorta and left atrium, respectively. Left ventricular aneurysms, usually the result of a previous myocardial infarction, occasionally result in a localized bulge that projects beyond the normal ventricular contour or an angulation of the left ventricular contour In the absence of heart failure, left ventricular hypertrophy must be massive before the heart shadow enlarges.

52. Right atrial enlargement Secondary to right ventricular failure Volume loading-Tricuspid regurgitation, ASD, VSD, Anomalous pulmonary venous return Pressure loading-Tricuspid stenosis , tricuspid valve obstruction from tumor or thrombus

53. Isolated right atrial enlargement is uncommon and usually is due to tricuspid stenosis or right atrial tumor. Right atrial dilatation associated with other chamber enlargement, primarily right ventricular enlargement, can be seen in several conditions, such as tricuspid regurgitation, pulmonary arterial hypertension, shunts to the right atrium, and cardiomyopathies .

54. Selective Right Atrial Enlargement Enlarged and globular heart right heart border becomes more convex protrudes to the right away from the midline (>5-5.5cm ), >3cm from right lat vertebra.

55. There may be associated with dilatation of SVC and IVC that causes widening of right superior mediastinum and an additional border in right cardiophrenic angle Fill in of the space between the sternum and the front of the upper part of the cardiac silhouette in the lateral radiograph

56. Marked isolated right atrial enlargement resulting in a “box-shaped” heart is seen in Ebstein’s malformation of the tricuspid valve . This configuration of the heart is the result of marked angulation at the superior vena caval -right atrial junction as the right atrium enlarges.

57. Right ventricular enlargement Volume loading-Tricuspid regurgitation, pulmonary regurgitation, ASD, VSD, Anomalous pulmonary venous drainage Pressure overload-Pulmonary HTN, Pulmonary stenosis , Acute PE

58. Signs Area of contact between the front surface of the heart and the sternum increases . The characteristic elevation of the apex of the heart . Dilatation of the right ventricle may cause tilting-up and posterior displacement of the left ventricle if this is normal in size. Selective right ventricular enlargement include a large main pulmonary artery and abnormal peripheral pulmonary arteries, which may be increased, pruned, or decreased .

59. Pericardial effusion

60. Narrow vascular pedicle Cardiomegaly directly proportional to severity of pericardial effusion This shadow has a rounded, globular appearance with NON particular chamber enlargement Cardiophrenic angle become more and more acute Oligaemic pulmonary vascular markings Marked change in cardiac silhouette in decubitus posture

61. Pulmonary vasculature Pulmonary arteries and veins provide information about the cardiovascular system Visualisation of their abnormalities can only be achieved reliably with a technically good erect PA chest film. Visualisations depend on the silhouette sign Underexposed film may make vessels appear more prominent.

62. Normal Pulmonary venous hypertension Pulmonary arterial hypertension Increased flow Decreased MAIN PULMONARY ARTERY RIGHT PULMONARY DESCENDING ARTERY DISTRIBUTION OF VESSELS- CENTRAL VS PERIPHERAL, UPPER LOBE VS LOWER LOBE WHAT TO SEE

63. Main Pulmonary Artery

64. Normal Pulmonary vascular pattern Begins with main pulmonary artery which forms convexity on the left mediastinal border between the arch of aorta and the straight left heart border. Divides into left and right pulmonary arteries, which divide in an orderly manner and gradually taper towards periphery.

65. Left Pulmonary Artery continues as a branch of main pulmonary artery before branching. Right pulmonary artery arises sharply from the main pulmonary artery, passing rightwards into the mediastinum . Descending branch of RPA is identified on the lower border of right hilum whose maximum diameter is 16 mm for males and 15 mm for females. LPA and left hilum are 1 cm above the RPA

66. Veins are wider, less well defined and branch less often than the companion arteries. Located medial to companion arteries in the upper zones, overlap each other in mid zone and lateral to the artery in the lower zone. Pulmonary veins converge in to the left atrium 2-3 cm below the hilum .

67. The lower lobe vessels are 2-3 times larger than the upper lobe vessels. In erect chest radiography, vessels in 1 st ICS are <3mm in diameter and those just above the diaphragm are upto 6 mm.

68. If we draw a tangent line from the apex of the left ventricle to the aortic knob (red line) and measure along a perpendicular to that tangent line (blue line) The distance between the tangent and the main pulmonary artery (between two small green arrows) falls in a range between 0 mm (touching the tangent line) to as much as 15 mm away from the tangent line

69. 27 Small pulmonary artery Truncus arteriosus Tetralogy of Fallot Main pulmonary artery is more than 15 mm from tangent

70. Abnormal pulmonary vascular patterns Pulmonary arterial hypertension Pulmonary venous hypertension Pulmonary plethora Pulmonary oligemia

71. Pulmonary arterial hypertension Systolic pressure more than 30 mm Hg in the presence of normal systemic pressure. Causes : Long standing L-R shunts Intrinsic lung disease Pulmonary thromboembolic disease. Secondary to increase in pulmonary venous pressure.

72. Features Increased convexity of the pulmonary artery on the left heart border Increased diameter of descending RPA Discrepancy between central and peripheral vessels Cardiomegaly Calcification of MPA and proximal branches

73. Increased pressure Increased flow Main pulmonary artery projects beyond tangent

74. 16

75. Venous hypertension PVH is said to be present when the pulmonary capillary wedge pressure exceeds the normal range:8-12 mm of Hg. Causes: impairment to the forward flow of blood through the left side of heart ( mitral stenosis , impaired left ventricular function) Stage 1: cephalisation of the blood flow (13-19 mm of Hg)

76. RDPA >16

77. Stage 2: interstitial edema , pleural effusion (19-25mm Hg) Kerly lines, peribronchial cuffing Background haze Septal and interstitial oedema

78. Stage 3 : Alveolar oedema (>25) Bat wing appearance

79. Signs of plethora 1 Presence of shunt vessels, end on vessels more than 2 times the diameter of accompanying bronchus 2. Prominent upper and lower zone vessels . En-face vessels below 10 th posterior rib Prominent vessels below the crest of diaphragm RDPA diameter more than that of trachea RDPA >16mm in diameter >6 vessels in peripheral one third of lung Prominent hilar vessels on lateral view In infants and children, generalized mottling may be seen

80. Pulmonary Oligemia  Decreased flow proximal to origin of main pulmonary artery  Small pulmonary artery  Empty pulmonary bay  Pulmonary vessels small  Lung hypertranslucent  Lateral view shows diminution of hilar vessels

81. Approach Is left atrium enlarged? Is main pulmonary artery Big or bullous ? Is main pulmonary artery segment concave? Is heart globular?

82. Enlarged left atrium Assess Pulmonary vasculature Normal Mitral regurgitation ( cardiomegaly ) Pulmonary venous HTN Mitral stenosis ( normal Heart size) Left atrial myxoma Papillary muscle dysfunction Left heart failure Increased flow Shunts- VSD, PDA Pulmonary arterial hypertension MS- with features of PVH VSD, PDA with features of pulmonary plethora