This document provides an overview of cardiac anatomy and various imaging techniques used to examine the heart. It describes the layers of the pericardium and positions of the heart within the chest. It then details the anatomy of each chamber of the heart and major vessels, as well as standard imaging planes and cardiac imaging modalities like echocardiography, CT, MRI, and angiography. Standard views like the two chamber, three chamber, and four chamber views are explained as well as how cardiac gating improves imaging by reducing motion artifacts.

1. CARDIAC ANATOMY AND
IMAGING TECHNIQUES
DR MRUDULA
FIRST YEAR PG

3. INTRODUCTION
• The heart lies in the anterior mediastinum and posterior to the
sternum.
• The heart is within a fibrous pericardial sac, extends till root of
the aorta and pulmonary artery.
• The pericardium is lined by two layers.
• The fibrous pericardium and the serous pericardium.
• Between these two layers is a very small amount of fluid ,it
allows free movement of the heart within the pericardial sac.
• The pericardium is normally paper thin measuring 2mm or less.

5. PERICARDIAL SINUSES
• SVC ,IVC and the pulmonary
veins are enclosed within a single
fold of pericardium, which contains
a recess known as the
oblique sinus. It is posterior to left
atrium.
• The outflow tracts- aorta
and pulmonary artery
are enveloped separately. Between
the major inflow and outflow
vessels there is a transverse
pericardial sinus.

6. CARDIAC SURFACES
• APEX:
Formed by left ventricle.
• BASE:
Formed by left atrium and little by right atrium.
• ANTERIOR SURFACE(sternocostal):
Formed mainly by the right ventricle,
• INFERIOR SURFACE(DIAPHRAGMATIC):
Formed by right ventricle mostly.
• RIGHT SURFACE:
Formed by the right atrium superiorly and right ventricle inferiorly.
• LEFT SURFACE:
Formed mainly by left ventricle and a little superiorly by left atrium.

7. • The apex of the heart is normally oriented downwards and leftwards.
• In tall slim individuals, hyperinflated lungs, younger age-
vertical orientation of heart.
• In short individuals, poor air entry, elder age – horizontal orientation.

8. RIGHT ATRIUM
• Right atrial
appendage is triangular and
broad based , contains
small muscular bundles(pectinat
e muscles) that run parallel to
atrium.

9. • The crista terminalis is a smooth
muscular ridge in the superior
aspect of the right atrium.
• Crista terminalis
separates posterior -sinus
venosus (smooth part of
the right atrium) and
anterior trabecularized part(right
atrial appendage).

10. • Coronary sinus, the major
draining vein of the heart runs in
the posterior AV groove and
enters the posterior wall of the
right atrium between the
tricuspid valve and the inferior
vena cava.
• This opening is guarded by valve
of coronary sinus or Thebesian
valve.

11. SUPERIOR VENA CAVA
• Normal diameter – upto 2 cm.
• Formed by the union of right and left brachiocphalic veins at the level
of first right coastal cartilage.
• It enters the right atrium at the level of third coastal cartilage.

13. INFERIOR VENA CAVA
• Formed by the confluence of two common iliac veins at the level of L5
vertebra.
• Drains venous blood from the lower trunk, abdomen, pelvis and
lower limbs to the right atrium of the heart.

14. RIGHT VENTRICLE
• Most anterior of the cardiac
chambers and has a heavily
trabeculated apex and papillary
muscles.
• It is rhomboid in shape and the
wall of right ventricle is thinner
compared to the left ventricle.
• 3 papillary muscles:
Anterior - largest
Posterior - smallest
septal

15. • Moderator band
aka septomarginal
trabeculation - a muscular band
extending from interventricular
septum to the base of
anterior papillary muscle and
contains the right branch of AV
bundle.

16. • The lower end conus has a
discrete muscular elevation,
the supraventricular crest,it
separates pulmonary valve from
the tricuspid valve.

17. PULMONARY ARTERY
• The pulmonary valve separates the right ventricular outflow tract of
the right ventricle from the pulmonary trunk.
• Its three leaflets or cusps - right , left and anterior.
• The main pulmonary artery passes posteriorly to the ascending aorta
and bifurcates, giving a right pulmonary artery and the left pulmonary
artery.
• The left pulmonary artery arches over the left main bronchus where
as the right pulmonary artery lies anterior to the right main bronchus
• The left pulmonary artery is slightly higher in position than right
pulmonary artery.

19. LEFT ATRIUM
• The left atrium is a smooth-walled
chamber
• Left atrial appendage is narrow-
based , pointing finger-like that
contains trabeculation is present
anteriorly
• The pulmonary veins drain through
posterior wall.
• It empties through the mitral valve
in its left lower anterior aspect.
• The left atrium usually lies slightly
higher than the right atrium

20. PULMONARY VEINS

21. LEFT VENTRICLE
• The left ventricle is a cone shaped structure with wall thickness of
1cm(right ventricle wall –4 or 5 mm).
• Its base is the fibrous skeleton of the mitral and aortic valves.
• Mitral leaflets are attached to chordae tendinae, which arise
from two large papillary muscles(anterolateral and posteromedial)
which attach to the free wall of the left ventricle.
• The outflow of the left ventricle is through the aortic valve.

23. AORTA
• The aortic valve has three cusps, cranial to it there is a slight dilatation
of aortic root called sinus of valsalva.
• It fills with blood during diastole, supplying the coronary arteries with
oxygen rich blood.
• The cusps of the aortic valves are named according to their
relationship with coronary arteries, namely the right coronary, left
coronary and non coronary cusp (R, L, N).

24. NORMAL AORTIC MEASUREMENTS :
• Aortic annulus: ~23 mm
• Aortic valve sinus / sinus of Valsalva: ~30 ± 5 mm
• Ascending aorta: 31 ± 4 mm
• Proximal to the brachiocephalic trunk: ~29 ± 4 mm
• Proximal transverse arch: ~28 ± 4 mm
• Distal transverse arch: ~26 ± 4 mm
• Aortic isthmus: ~25 ± 4 mm
• At the diaphragm: ~24 ± 4 mm

26. INTERATRIAL SEPTUM :
• A fibromuscular structure dividing the right and let atrium.
• The fossa ovalis is the small oval depression in the interatrial septum
at the site of the closed foramen ovale, which closes once fetal
circulation ceases in the first few minutes of postnatal life.

27. INTERVENTRICULAR SEPTUM
• The annulus of the tricuspid valve lies slightly more apically than the
annulus of the mitral valve and this creates a small segment of
septum lying between the left ventricle and the right atrium. This is
termed the 'ventriculoatrial septum’ .
• Superior part of the ventriculoatrial septum is very thin -the
membranous septum.
• Between the mitral and tricuspid valves ,the muscular portion of the
interventricular septum - inlet or basal septum.
• Further down septal areas are called mid and apical muscular septal
regions.

28. • The vascular territories of the myocardium are divided into 17
myocardial segments according to the AHA nomenclature.
• This standard segmentation model can be used in cardiac nuclear
tests, computed tomography, magnetic resonance imaging,
echocardiography and coronary angiography
• In the long axis, the left ventricle is divided into equal thirds named
the basal, mid and apical thirds. The tip of the apex forms a separate
final segment
• viewed in short axis they form rings that are numbered
counterclockwise.
LEFT VENTRICULAR SEGEMENTATION

30. CARDIAC IMAGING TECHNIQUES
The main techniques for examining the heart are:
• Plain chest radiography
• Echocardiography (cardiac ultrasound)
• CT scanning
• MRI scanning
• Radionuclide imaging
• Angiography

31. CHEST XRAY
1. cardiac size and contour - clue to chamber enlargement.
• PA chest film the cardiothoracic ratio can be measured.
• Cardiothoracic ratio is normally below 50%.
• AP films normal value can be accepted as 55%. In infants the
normal value can also be 55%.
2. evaluation of the lung fields –clue to cardiac function.
3. Additional features related to cardiac disease which may include
metallic or other implants, valvular calcifications.

33. CARDIAC AXIS IMAGING PLANES
• Cardiac imaging planes are standard orientations for displaying
the heart on MRI, CT, SPECT and PET similar to those used
in echocardiography.
• Include-
1. vertical long-axis (VLA) view or two chamber view
2. horizontal long-axis (HLA) view or four chamber view
3. Short axis view
4. Three chamber view
5. Five chamber view

34. TWO CHAMBER VIEW
• The 2-chamber view is achieved by
rotating the images
perpendicularly to the mitral valve
and parallel to the cardiac septum.
This axis gives an overview of the
left atrium ventricle and mitral
valve.
It is a good view for analyzing
ventricular function, especially that
of the inferior and anterior walls.

35. THREE CHAMBER VIEW
• When the border between the
mitral and aortic valves is
localized on the axial slices and
the images are rotated from this
point, a 3-chamber view like the
image on the left can be
reconstructed.

36. FOUR CHAMBER VIEW
• Achieved by rotating upwards from
the apex of the heart on the axial
slices.
• The right ventricle is projected next
to the right atrium, and the left
ventricle next to the left atrium.
The mitral valve comes into view
and - depending on the contrast
protocol - the tricuspid valve may
also be visible.
• The apex of the heart is well
demarcated.

37. FIVE CHAMBER VIEW
• similar to the 4-chamber view,
but additionally displays the
aortic valve and left ventricular
outflow tract.
This view is achieved by rotating
the 4-chamber view a little more
cranially.

38. SHORT AXIS VIEW
• Obtained in an oblique coronal
plane relative to thorax, down
the barrel of the LV lumen.
• As one progresses from
the MV toward the apex in
the short axis, the basal , middle
and apical portions of
the LV myocardium can
be evaluated.

39. CARDIAC GATING
• Cardiac imaging is degraded by motion artefact unless cardiac gated .
• There are two forms of cardiac gating
1. Prospective gating –
detects the QRS complex of the ECG then triggers the application of the
sequence, such that the image is formed from a specific part of the
cardiac cycle.
2. Retrospective gating-
sequence is repeated continuously with a constant repeat time while
the ECG is monitored. The data are sorted at the completion of the
sequence and adjusted to give images at specific parts of the cardiac
cycle.

40. REFERENCES
• David sutton text book of radiology and imaging
• Radiology assistant
• Radiopedia

41. THANKYOU