Dr/AHMED ESAWY

An Article By

Dr. Ahmed Esawy

MBBS M.Sc. MD

Dr/AHMED ESAWY

Dr/AHMED ESAWY

5 PARTS

• 1-CT radiological anatomy

• 2-pathology

• 3-technique

• 4-indication

• 5-Manifestation of coronary artery diseases in

MSCTCA/MRCA

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coronary

radiological

Anatomy

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Coronary arteries

The epicardial coronary artery system consists of the left and right coronary arteries.

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Normal Anatomy

R and L coronary arteries arise from the R and L aortic sinuses (of Valsalva)

Usually within 1cm superior to aortic valve

Arteries originate orthogonal to aortic wall

Epicardial (extramural course) course

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The aortic valve has three leaflets, each having a cusp or cup-like configuration. These are known as the left coronary cusp (L), the right coronary cusp (R) and the posterior non-coronary cusp (N). Just above the aortic valves there are anatomic diltations of the ascending aorta, also known as the sinus of Valsalva. The left aortic sinus gives rise to the left coronary artery. The right aortic sinus which lies anteriorly, gives rise to the right coronary artery. The non-coronary sinus is postioned on the right side.

Origin of coronary artery

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Coronary artery

• The coronary artery arises just

superior to the aortic valve and

supply the heart

• The aortic valve has three cusps –

#left coronary (LC),

#right coronary (RC)

#posterior non-coronary (NC)

cusps.

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Left coronary (LC), right coronary (RC) and posterior non-coronary (NC) cusp

The left coronary artery (LCA) is also known as the left main. The LCA arises from the left coronary cusp.

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RCA LCA

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On the left an overview of the coronary arteries in the anterior projection. Left Main or left coronary artery (LCA)

Left anterior descending (LAD) diagonal branches (D1, D2) septal branches

Circumflex (Cx) Marginal branches (M1,M2)

Right coronary artery Acute marginal branch (AM) AV node branch Posterior descending artery (PDA)

RCA, LAD and Cx in the anterior projection

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On the left an overview of the coronary arteries in the right anterior oblique projection. Left Main or left coronary artery (LCA)

Left anterior descending (LAD) diagonal branches (D1, D2) septal branches

Circumflex (Cx) Marginal branches (M1,M2)

Right coronary artery Acute marginal branch (AM) AV node branch Posterior descending artery (PDA)

RCA, LAD and Cx in the right anterior oblique projection

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On the left an overview of the coronary arteries in the lateral projection. Left Main or left coronary artery (LCA)

Left anterior descending (LAD) diagonal branches (D1, D2) septal branches

Circumflex (Cx) Marginal branches (M1,M2)

Right coronary artery Acute marginal branch (AM) AV node branch Posterior descending artery (PDA)

RCA, LAD and Cx in the lateral projection

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SEGMENTAL CORONARY ARTERY ANATOMY

16 SEGMENTS

MODIFIED 17 SEGMENTS

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Right coronary artery (1-4 segments)

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Left main coronary artery (5 segment)

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Left anterior descending coronary artery (6-10 segments)

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Left circumflex coronary artery (11-15 segments)

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ramus intermedius

The ramus intermedius is a variant coronary artery resulting from trifurcation of the left main coronary artery . It is present in 20% (range 15-30%) of the population. It can have a course similar to the obtuse marginal branches of the left circumflex artery or the diagonal branches of the left anterior descending and thus can supply either the anterior or medial aspect of the heart .

SEGMENT NAME VESSEL NAME SEGMENT NO

Ramus intermedius Ramus intermedius 17

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Modified 17-segment of the AHA reporting system Dr/AHMED ESAWY

Modified 17 segments AHA Right Coronary Artery

SEGMENT NAME VESSEL NAME SEGMENT NO

Proximal RCA Right coronary artery 1

Mid RCA 2

Distal RCA 3

Posterior descending artery 4

Right posterolateral 16

left posterolateral

15

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Modified 17 segments AHA Left Circumflex artery

SEGMENT NAME VESSEL NAME SEGMENT NO

Proximal LCA Left circumflex artery 11

Distal LCA 13

First obtusomarginal OM 12

second obtusomarginal OM 14

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Normal coronary arteries as seen on curved multiplanar reformations

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Left coronary artery

• Arises from left coronary

cusps

• Travels between RVOT

anteriorly and left atrium

posteriorly.

• Almost immediately

bifurcate into left anterior

descending and left

circumflex artery.

• Length – 10-15mm .

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LCA divides into LAD and Cx

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Left coronary artery

LAD

Diagonal artery

Lt Conus artery

Anterior Septal br

Circumflex artery

Obtuse marginal branches

Ventricular branches

Atrial rami

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LEFT CORONARY ARTERY Dr/AHMED ESAWY

LT CORONARY ARTERY

1) Left atrium.

2) Ventricles

i) Greater part of the left ventricle, except the area adjoining the posterior IV groove.

ii) A small part of the right ventricle adjoining the anterior IV groove.

3) Anterior part of the IV septum.

4) A part of the left br. Of the AV bundle.

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DOMINANCE • Determined by the arrangement that which artery

reaches the crux & supply posterior descending

artery

• The right coronary artery is dominant in 85% cases.

• 8% cases - - circumflex br of the left coronary artery

• 7% both rt & lt coronary artery supply posterior

IVseptum & inferior surface of the left ventricle-here

it is balanced dominance.

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Coronary dominance is based on the vessel that gives rise to the posterior descending artery which supplies the Atrio-ventricular node.

Recognized by the presence of septal perforating

branches, arises from the RCA in 80% from and the LCx in 10% of the population.

Co-Dominance is found in 10% of the population

where the posterior interventricular artery is formed by both the RCA and LCx.

Dominance

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Dominant RCA

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In 15% of cases a third branch arises in between the LAD and the Cx, known as the ramus intermedius or intermediate branch. This intermediate branche behaves as a diagonal branch of the Cx.

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The Left coronary artery

• Oblique volume-rendered image of the top of the heart shows the origins of the left main coronary artery.

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The LAD travels in the anterior interventricular groove and continues up to the apex of the heart. The LAD supplies the anterior part of the septum with septal branches and the anterior wall of the left ventricle with diagonal branches. The LAD supplies most of the left ventricle and also the AV-bundle.

LAD

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The Left Anterior Descending artery

• Oblique volume-rendered image shows the LAD artery

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CT image of the LAD in RAO projection

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The diagonal branches come off the LAD and run laterally to supply the antero-lateral wall of the left ventricle. The first diagonal branch serves as the boundary between the proximal and mid portion of the LAD. There can be one or more diagonal branches: D1, D2 , etc.

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The proximal left anterior descending coronary artery segment (6) is the anterior branch of the left main coronary artery (5, Panels A–D). Segment 6 of the left anterior descending coronary artery then bifurcates into the mid-left anterior descending (7) and the first diagonal branch (9, Panels A–D). Further

In Panels E and F, the conus branch (arrows, first side branch of the RCA), which travels cranial to the proximal RCA segment, is also visible.

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caudally, the mid-left anterior descending coronary artery gives off the distal segment (8) and the second diagonal (10, Panels E–J)

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The Cx lies in the left AV groove between the left atrium and left ventricle and supplies the vessels of the lateral wall of the left ventricle. These vessels are known as obtuse marginals (M1, M2...), because they supply the lateral margin of the left ventricle and branch off with an obtuse angle. In most cases the Cx ends as an obtuse marginal branch, but 10% of patients have a left dominant circulation in which the Cx also supplies the posterior descending artery (PDA). Marginal branches arise from the Cx and supply the lateral Margin of the left ventricle.

Circumflex (Cx)

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The Left Circumflex artery

• An axial oblique volume-rendered image shows the LCX artery

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Circumflex and LAD seen in Lateral projection

.

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The proximal LCX segment (11) is the posterior branch of the left main coronary artery (5, Panels A–D). Further down, the proximal left circumflex splits into the mid-left circumflex (13) and the first (obtuse) marginal branch (12, Panels E–H). The mid-left circumflex (13) then gives off the distal left circumflex (15, Panels F–H)

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obtuse) marginal branches (14, Panels E–J), which supply the inferolateral myocardial segments

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(In the case of left coronary artery dominance, the distal circumflex (15) ends as the posterior descending artery (4a), whereas in right coronary dominance, as in this case,the RCA gives rise to the posterior descending and at least one posterolateral branch. The sinus node artery (arrow in Panels A and B) is the first branch of the LCX in this patient.; Asterisk papillary muscles;

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Right coronary artery

• Originates from right coronary sinus of Valsalva

• Courses through the right AV groove between the right atrium and right ventricle to the inferior part of the septum

.

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Right Coronary Artery (RCA)

In 50-60% the first branch of the RCA is the small conus branch, that supplies the right ventricle outflow tract. The next branches are some diagonals that run anteriorly to supply the anterior wall of the right ventricle. The large acute marginal branch (AM) comes off with anacute angle and runs along the margin of the right ventricle above the diaphragm. The PDA supplies the inferior wall of the left ventricle and inferior part of the septum.

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Branches of RCA

Right coronary artery

Conus artery

Sinu nodal artery

Marginal artery

Post. Descending IV artery

AV nodal artery-

Conus branch

SINU NODAL BRANCH

AV Nodal Branch

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RCA, LAD and LCx in Anterior projection

.

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The Right coronary artery

• oblique volume-rendered image shows the RCA .

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• Conus branch – 1st branch supplies the RVOT

• Sinus node artery – 2nd branch - SA node.(in 40%

they originate from LCA)

• Acute marginal arteries-Arise at acute angle and runs

along the margin of the right ventricle above the

diaphragm.

• Branch to AV node

• Posterior descending artery : Supply lower part of the

ventricular septum & adjacent ventricular walls.

Arises from RCA in 85% of case.

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Right coronary anatomy

AO

LA

RCA

CONUS BR

RCA

SAN

1 2

3 4 RCA

AM

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RCA

AM AM

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Area of distribution RT CORONARY ARTERY----

1)Right atrium

2)Ventricles

i) greater part of rt. Ventricle except the area adjoining the anterior IV groove.

ii) a small part of the lt ventricle adjoining posterior IV groove.

3)Posterior part of the IV septum

4)Whole of the conducting system of the heart, except part of the left br of AV bundle

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LEFT: RCA comes off the right sinus of ValsalvaRIGHT: Conus artery comes off directly from the aorta

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The large acute marginal branch (AM) supplies the lateral wall of the right ventricle. In this case there is a right dominant circulation, because the posterior descending artery (PDA) comes off the RCA Dr/AHMED ESAWY

a

The RCA with all its segments in axial slices

thickness in the axial orientation for comparison (right panels). The proximal segment of the RCA (1) comes off the aorta, arising from the right sinus of Valsalva (Panels A and B). It first moves anteriorly and then (as segment 2) caudally in the right atrioventricular sulcus

(Panels C and D) to the posterior surface of the heart (Panels E and F), where it again moves in the horizontal plane on the diaphragmatic Dr/AHMED ESAWY

The RCA with all its segments in axial slices

face of the heart as segment 3. At the crux cordis, segment 3 bifurcates into the posterior descending artery (4a) and the right posterolateral branch (4b in Panels G and H).

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In cases of dominance of the RCA (as in this case), segments 4a and b are side branches of the RCA. In case of left coronary artery dominance, the posterior descending artery (4a) is part of the LCX

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Three dimensional reconstruction of the heart (A). Curved multiplanar reconstructions of the RCA (B), LAD (C) and LCx arteries (D) revealed the

absence of atherosclerotic abnormalities (LAD: left

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A- the RCA is a dominant patent artery of normal caliber. B- The circumflex artery is patent of normal caliber.

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