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Coronary Anatomy / Normal VariantsAlison G. Wilcox, MD

CLINICAL INDICATIONS FOR CARDIAC CTA

Alison G. Wilcox MDAssociate Professor of Radiology

Section Chief- Cardiothoracic ImagingUSC- Keck School of Medicine

[email protected]

CORONARY ANATOMY AND NORMAL VARIANTS

USC School of MedicineCardiothoracic Imaging

CLINICAL INDICATIONS FOR CARDIAC CTA

Alison G. Wilcox MDSection Chief- Cardiothoracic ImagingUSC- Keck School of [email protected]

[email protected]

Acknowledgements/Disclosures

Dr Jabi Shriki –USC

Dr. Chris Lee-USC

Dr. Bonnie Garon- USC


Dr. Jerold Shinbane- USC

Dr. Tony De France-CVCTA

Dr. John Lesser-Minneapolis Heart Institute

[email protected]

ObjectivesObjectives

• Understand the important role of Cardiac CT in the evaluation of coronary anatomy

• Recognize the normal and anatomic variants in coronary anatomy


variants in coronary anatomy• Understand the importance of some

variants as they relate to surgical or percutaneous intervention

Role of Cardiac CT in Evaluation of Role of Cardiac CT in Evaluation of Coronary anatomyCoronary anatomy

• Cardiac computed tomography (CCT) has became modality of choice for evaluation of coronary anatomy.– A higher sensitivity for detection of coronary anomalies is

achieved, compared to conventional angiography.


ac e ed, co pa ed to co e t o a a g og ap y– The entire arterial and coronary arterial tree is opacified with

a single administration of contrast.– Other mediastinal vascular anomalies are detected as well

as the relationship between the coronary arteries and other vascular structures.

Normal anatomy


Right Coronary Artery


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Conus branch RCA


Sa nodal branch

Conus branch-separate orifice




Left Coronary Artery


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LCA

LAD

SEPTAL PERFORATORS

diagonal


CX RI

RI

3-D Anatomy:


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PDA


PDA

PLA


MID CX

OM 2

PROX CX AV CX


OM 1


Report of the Ad Hoc Committee for Grading of Coronary Artery Disease, Council on Cardiovascular Surgery, American Heart Association

WG Austen, et al. Circulation 1975 51: 5- 40 USC School of MedicineCardiothoracic Imaging

SCCT Coronary Segmentation Diagram. Axial coronary anatomy definitions derived, adopted, and adjusted from WG Austen,JE Edwards, RL Frye, GG Gensini, VL Gott, LS Griffith, DC McGoon, ML Murphy, BB Roe: A reporting system on patients evaluated forcoronary artery disease. Report of the Ad Hoc Committee for Grading of Coronary Artery Disease, Council on Cardiovascular Surgery,American Heart Association. Circulation. 1975;51:5–40.

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Segment Abbreviation Description

Proximal RCA pRCA Ostiumof the RCA (right coronary artery) to one half the distance to the acute margin of heart

Mid RCA mRCA End of proximal RCA to the acute margin of heart

Distal RCA dRCA End of mid RCA to origin of the PDA (posterior descending artery)PDA RCA R PDA PDA from RCA

PLB RCA R PLB PLB (posterior lateral branch) from RCA

LM LM Ostiumof LM (left main) to bifurcation of LAD (left anterior descending artery) and LCx (leftcircumflex artery)

Proximal LAD pLAD End of LM to the first large septal or D1(first diagonal), whichever is most proximal

Mid LAD mLAD End of proximal LAD to one half the distance to the apexDistal LAD dLAD End of mid LAD to end of LADDiagonal 1 D1 First diagonal branch D1


g gDiagonal 2 D2 Second diagonal branch D2

Proximal LCx pCx End of LM to the origin of the OM1 (first obtuse marginal)

OM1 OM1 First OM1 traversing the lateral wall of the left ventricle

Mid and distal LCx LCx Traveling in the AV groove, distal to the first obtusemarginal branch to the end of the vessel or

origin of the L PDA (left posterior descending artery)OM2 OM2 Secondmarginal OM2PDA LCx L PDA PDA from LCx

Ramus intermedius RI Vessel originating from the left main between the LAD and LCx in case of a trifurcationPLB L L PLB PLB from LCx

Dashed lines represent division between RCA, LAD, and LCx and the end of the LMPLB 5 PLV

(posterior left ventricular branch) Additional nomenclature may be added for example: D3,

R PDA2, SVG (saphenous vein graft) mLAD

RCA/SEG 3

RCA/SEG 2

RCA/SEG 1


PL/SEG 16

PDA/SEG 4

RCA

LAD 6

LM 5

LCX 11

LAD8

D9

D10

LAD 7


LCA

CX/SEG 15

CX/SEG 13

OM /SEG12

OM/SEG 14


OM /SEG12

LCA

DOMINANCE

- 85% right


- 7.5% left- 7.5% co-dominant

RIGHT DOMINANT

Right supplies both PDA and PL branches


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LEFT DOMINANT

Left supplies PDA via AV groove branch of


left circ

CODOMINANT

Either right supplies PDA and AV groove branch of left circumflex terminates in PL branches OR


branches, OR two PDA branches

Variant Anatomy


Classification Scheme for Anomalies

• Normal (minor) variants (separate conusbranch, ramus intermedius, often ignored).

• Abnormal number of coronary arteries (absence or duplication).Ab l i i


• Abnormal origin • Abnormal course (often includes origin). • Abnormal termination (anything other than

the myocardium).

Scheme

• Potentially Hemodynamically significant:– Atresia.– Shunts: ALCAPA, fistulae, etc.– Course: Interarterial variant.


• Non-hemodynamically significant:– Lots of these and finding more every day…..

Non-atherosclerotic diseases:

Variants. Anomalies.


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Non-atherosclerotic diseases:

Significant. Incidental.


Classification of anomalies, variants:

Normal (minor) variants:• Separate conus branch (~35%).• Absence of LMCA (with separate CFX and

LAD) ( 2%)


LAD) (~2%).• SA nodal branch from CFX (~20%).• Ramus intermedius (~25%).

Conus branch:• No independent clinical

significance.• Some argue that this

artery should be l ti l th t i d


selectively catheterized.• Variety of names:

– Adipose, infundibular, third coronary artery.

Ramus intermedius:• Separate artery between

LAD and CFX (trifurcation of LMCA).

• Not significant.• Variable in size.


• Usually has some inverse relationship with diagonal arteries

“Absent” LMCA:• Separate origins of the

LAD and CFX.• Not significant, but may

necessitate separate catheterization of ostia.


Absent/Atretic LMCA:

• Rare variant.• ~ 20 cases in the literature.• May be under-recognized.


• Usually significant, with RCA to left collaterals forming, which are usually not sufficient to LVs oxidative demands.

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Atretic LMCA:


Atretic LMCA:


LADLAD

CFXCFX

Atretic LMCA:


Atretic LMCA:

CFXCFX

Bypass vesselBypass vessel


LAD

Coronary Artery DuplicationCoronary Artery Duplication

• Duplication of a coronary artery is an uncommon finding.• The LAD is the most commonly duplicated artery,

although duplication of other coronary arteries has been reported.

• Variants of coronary artery duplication are usually not h d i ll i ifi t


hemodynamically significant.

Duplication of the LAD:


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Duplication of the LAD:

Ao


DUAL LAD

Diagonal branch supplies LAD distribution


DUAL LAD

Conus branch supplies LAD distribution


High origin:

• 1 cm above sinotubular junction.• Usually the RCA.• Not hemodynamically significant.• May complicate percutaneous interventions and


• May complicate percutaneous interventions and surgery.

• Uncommon.• Association with bicuspid aortic valve.

High RCA origin:


High RCA origin:High RCA origin:

Sinotubularjunction


Normal RCA origin

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High Origin


High left

High right

Classification of anomalies, variants:

Anomalies of course:• A (Anterior to right ventricular outflow

tract)/Prepulmonic.• B (Between aorta and pulmonary trunk)/Interarterial.


• C (Through the Crista supraventricularis)/Transseptal.• D (Dorsal to the aorta)/Retroaortic.• Intramyocardial course (myocardial bridging).• Shepherd’s crook RCA.

PrepulmonicInterarterial

RetroaorticTransseptal


LAD Bridge

Common variant-15-20% of patients

Thought


to be incidental, difficult to identify on cath

Bridge• Rarely

significant Narrowing greater in systole than diastole.

• Sparing of atherosclerosis


• Deeper bridging may be more significant. > 2.3mm below surface

• Difficult to identify arteries during coronary artery bypass surgery.

Right Coronary Bridge


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Extracardiovascular Coronary Artery Extracardiovascular Coronary Artery TerminationTermination

• Coronary artery termination on non-cardiac and non-vascular structures.

• Coronary artery may give off branch to supply extracardiac structure.

• Difficult to identify on CCT due to small caliber of vessels.


• May be normal connections between coronary vasculature and bronchial or other arterial systems. (Greenberg)

• Pathways may be accentuated in the presence of atherosclerosis when a significant pressure gradient is present between the two vascular systems. (Moberg)

Extracardiovascular Coronary Artery Extracardiovascular Coronary Artery TerminationTermination

PDA draining into extracardiac

diaphragmatic vessel


PDA Phrenic arteryShriki et al, in press

Shepherd’s crook RCA:

• Usually an excessively tortuous RCA.• The curvature makes catheterization and

subsequent instrumentation somewhat difficult.• There are classification systems, but the


There are classification systems, but the important details are the location of the “crook” and the acuity of the curvature.



SHEPHERD’S CROOK


Angioplasty and Stenting may be problematic

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Coronary May Traverse Chambers

• Right coronary through


the right atrium

Conclusion

• Important to be familiar with normal anatomy, variant anatomy, and nomenclature

• Some variants are clinical relevant while


• Some variants are clinical relevant while others are thought to be relatively benign

• Variants are often important in surgical or interventional planning

• CCTA reveals 3D relationships more readily than angiography

Resources1.Cademartiri F, La Grutta L, Malagò R, Alberghina F, Meijboom WB, Pugliese F, et al . Prevalence of anatomical variants and coronary anomalies in 543 consecutive patients studied with 64-slice CT coronary angiography. Eur Radiol2008;18:781-91.2.Li J, Soukias ND, Carvalho JS, Yen Ho S. Coronary arterial anatomy in tetralogy of fallot: morphological and clinical correlations. Heart 1998;80:174-183. Isolated Coronary Artery Anomalies—emedicine J Li,a N D Soukias,b J S Carvalho,b S Yen Hoa

3.Roberts, William O., Maron, Barry J. Evidence for Decreasing Occurrence of Sudden Cardiac Death Associated With the Marathon. J Am Coll Cardiol 2005 46: 1373-1374.4.Eckart R, Scoville S, Campbell C, Shry E, Stajduhar K, Potter R, et al. Sudden Death in Military Recruits. Ann Intern Med December 7, 2004 141:I-26.5.Basso C, Thiene G. Congenital coronary artery anomalies at risk of myocardial ischaemia and sudden death: A report. Business Briefing: European Cardiology 2005.6.Elena Peña, Elsie T. Nguyen, Naeem Merchant, and Garole Dennie ALCAPA Syndrome: Not Just a Pediatric

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Disease Radiographics March 2009 29:553-565.7.NeufeldHN, Lester RG, Adams P Jr, et al. Congenital communication of a coronary artery with a cardiac chamber or the pulmonary trunk (coronary artery fistula). Circulation 1961;24:171–179.8.ReaganK, Boxt LM, Katz J. Introduction to coronary arteriography. Radiol Clin North Am 1994; 32:419–433.9.Geiringer E. The mural Coronary. Am Heart J 1951, Ishii T, Asuwa N, Ishikawa Y. The effects of myocardial bridge in coronary atherosclerosis and ischaemia. J Pathol 1998; 185:4-910.Zeina, Abdel-Rauf, Odeh, Majed, Blinder, Jorge, Rosenschein, Uri, Barmeir, Elisha Myocardial Bridge: Evaluation on MDCT Am. J. Roentgenol. 2007 188: 1069-1073.11.TioRA, Van Gelder IC, Boonstra PW, Crijns HJ. Myocardial bridging in a survivor of sudden cardiac near-death: role of intracoronary Doppler flow measurements and angiography during dobutamine stress in the clinical evaluation. Heart1997;77:280–282.12.GreenbergMA, Fish BG, Spindola-Franco H. Congenital anomalies of coronary artery: classification and significance. Radiol Clin North Am 1989;27:1127–1146.13.Moberg A. Anastomosis between extracardiac vessels and coronary arteries. Acta Radiol 1967;6: 177–192.

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