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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
CORONARY ANATOMY AND NORMAL VARIANTS
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CLINICAL INDICATIONS FOR CARDIAC CTA
Alison G. Wilcox MDSection Chief- Cardiothoracic ImagingUSC- Keck School of [email protected]
Acknowledgements/Disclosures
Dr Jabi Shriki –USC
Dr. Chris Lee-USC
Dr. Bonnie Garon- USC
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Dr. Jerold Shinbane- USC
Dr. Tony De France-CVCTA
Dr. John Lesser-Minneapolis Heart Institute
ObjectivesObjectives
• Understand the important role of Cardiac CT in the evaluation of coronary anatomy
• Recognize the normal and anatomic variants in coronary anatomy
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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.
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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
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Right Coronary Artery
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Conus branch RCA
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Sa nodal branch
Conus branch-separate orifice
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Left Coronary Artery
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LCA
LAD
SEPTAL PERFORATORS
diagonal
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CX RI
RI
3-D Anatomy:
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PDA
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PDA
PLA
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MID CX
OM 2
PROX CX AV CX
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OM 1
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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
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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
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PL/SEG 16
PDA/SEG 4
RCA
LAD 6
LM 5
LCX 11
LAD8
D9
D10
LAD 7
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LCA
CX/SEG 15
CX/SEG 13
OM /SEG12
OM/SEG 14
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OM /SEG12
LCA
DOMINANCE
- 85% right
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- 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
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left circ
CODOMINANT
Either right supplies PDA and AV groove branch of left circumflex terminates in PL branches OR
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branches, OR two PDA branches
Variant Anatomy
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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
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• 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.
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• 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.
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Classification of anomalies, variants:
Normal (minor) variants:• Separate conus branch (~35%).• Absence of LMCA (with separate CFX and
LAD) ( 2%)
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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
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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.
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• 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.
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Absent/Atretic LMCA:
• Rare variant.• ~ 20 cases in the literature.• May be under-recognized.
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• Usually significant, with RCA to left collaterals forming, which are usually not sufficient to LVs oxidative demands.
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Atretic LMCA:
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Atretic LMCA:
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LADLAD
CFXCFX
Atretic LMCA:
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Atretic LMCA:
CFXCFX
Bypass vesselBypass vessel
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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
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hemodynamically significant.
Duplication of the LAD:
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Duplication of the LAD:
Ao
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DUAL LAD
Diagonal branch supplies LAD distribution
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DUAL LAD
Conus branch supplies LAD distribution
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High origin:
• 1 cm above sinotubular junction.• Usually the RCA.• Not hemodynamically significant.• May complicate percutaneous interventions and
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• May complicate percutaneous interventions and surgery.
• Uncommon.• Association with bicuspid aortic valve.
High RCA origin:
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High RCA origin:High RCA origin:
Sinotubularjunction
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Normal RCA origin
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High Origin
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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.
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• C (Through the Crista supraventricularis)/Transseptal.• D (Dorsal to the aorta)/Retroaortic.• Intramyocardial course (myocardial bridging).• Shepherd’s crook RCA.
PrepulmonicInterarterial
RetroaorticTransseptal
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LAD Bridge
Common variant-15-20% of patients
Thought
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to be incidental, difficult to identify on cath
Bridge• Rarely
significant Narrowing greater in systole than diastole.
• Sparing of atherosclerosis
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• 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.
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• 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
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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
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There are classification systems, but the important details are the location of the “crook” and the acuity of the curvature.
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SHEPHERD’S CROOK
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Angioplasty and Stenting may be problematic
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Coronary May Traverse Chambers
• Right coronary through
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the right atrium
Conclusion
• Important to be familiar with normal anatomy, variant anatomy, and nomenclature
• Some variants are clinical relevant while
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• 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
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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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