Anatomy of the coronary circulation & Angiographic VISUALIZATION Dr Sandeep Mohanan Department of Cardiology Calicut Medical College 1/10/12

OUTLINE Coronary arterial anatomy Variations in coronary circulation Coronary venous anatomy Angiographic views of coronary arteries

Coronary arterial anatomy 1st anatomical drawings- Leonardo da Vinci Oblique inverted crown

The coronary arteries and their major branches are sub-epicardially located

Pericardium (Epicardium) Epicardial Vessel Subepicardium Myocardium Subendocardium

LCA ostium ~ 4mm RCA ostium~ 3.2mm

The LEIDEN convention 1R2LCx pattern Each artery arises from respective aortic sinuses - Right coronary sinus(anterior) - Left coronary sinus(left posterior) - Non-coronary sinus(right posterior) 1R2LCx pattern

Right coronary artery ~ 9.8cm 1)Conus artery/ Infundibular/ Third coronary/ Adipose /Arteria of Vieussens Separate ostium in 23% - 51% - Circle of Vieussens

Right coronary artery 2) Atrial branches of the RCA - < 1mm SA nodal artery ( Ramus crista terminalis) – 55-65%

Right coronary artery 3) Right ventricular branches Acute right marginal artery Ramus crista supraterminalis (Superior septal artery) – 12 -20% , males

Right coronary artery 4) Posterior descending artery Dominance Posterior septal branches - < 15mm 5) AV nodal artery - 80 -90%

Right coronary artery 6) Postero-lateral branches to the LV - Inferior wall of the LV

Clinical division of the RCA Proximal - Ostium to 1st main RV branch Mid - 1st RV branch to acute marginal branch Distal - acute margin to the crux

Left coronary artery LMCA 10-15mm(upto 30mm) length & 3-6mm(upto 10mm diameter) Trifurcates in 1/3rd : Ramus intermedius/ median artery/ left diagonal artery/straight LV artery Rare variations – absent LMCA/ pentafurcation

Left anterior descending artery - ~ 14.7 cm ; Type I (22%) , Type II & Type III - 2-9 diagonal branches 90deg bend after turning around P. conus as it gives off 2nd diagonal branch Right ventricular branches( left conal/pre-infundibular A) ~ 10 septal perforating branches (40-80mm X 0.5-1.2mm) anchors the LAD LAD supplies 45-55% of LV

LAD(contd) 1st proximal septal A is prominent (His Bundle and LBB) Myocardial bridging – 0.5-1.6% overall (28% in children) Rarely dual LADs

Clinical division of the LAD Proximal - Ostium to 1st major septal perforator Mid - 1st perforator to D2 (90 degree angle) Distal - D2 to end

Left circumflex artery ~9.3 cm long ; 1.5 -5mm Left atrial branches Kugel’s artery (Arteria anastomotica auricularis magna) LV branches are called the Obtuse marginal arteries LCx supplies 15-25% of LV (40-50% in dominant LV)

Clinical division of the LCX Proximal - Ostium to 1st major obtuse marginal branch Mid - OM1 to OM2 Distal - OM2 to end

Coronary segment classification system CASS investigators – 27 segments BARI – 29 segments ( ramus intermedius and 3rd diagonal branch) - Obstructive CAD : > 50% stenosis

Prognostication scores Califf scoring system Gensini scoring system Candell-Riera scoring system CASS investigators: - no. of vessels - no. of proximal segments - Global LV function

“Dominance” A misnomer giving rise to PDA, at least 1 PLV & AV nodal A (BARI classification) - 85% right dominant 8% left dominant 7% co-dominant (70%/ 10%/ 20% – Hurst’s THE HEART) Left dominance is 25-30% in Bi-AoV Gensini GG. Coronary Arteriography. Mount Kisco,NY: Futura Publishing Co; 1975:260–274.

Nodal blood supply Studies on nodal blood supply principally by James (1961) and Hutchinson( 1978) - James : SA node - RCA 55% & LCA 45% AV node- RCA 90% & LCA 10% Hutchinson : SA node - 65% & 35% AV node- 80% & 20% AV node may have dual supply in 2% cases

Arterial anastomoses Seen at the intracoronary/inter-coronary levels in abundance– significant in development in collaterals in CAD Most abundant at the septum Intracoronary : 1-2cm X 20- 250 micm Inter-coronary: 2-3 cm X 20-350 micm

Coronary artery variations 2 coronary artery system is a recent evolutionary acquisition Fish and amphibia – 1 coronary artery Birds – ~ 40% have single coronary arteries. 1-5% of those undergoing CAG Angelini P – Coronary artery anomalies – current clinical issues. Definition, classifications, incidence, clinical relevance and treatment guidelines. Tex Heart Inst J 2002;29:271-278

Coronary artery variations Definition of a coronary artery is not based on its origin and proximal course, but by focusing on its intermediate and distal segments/ its dependent microvascular bed. Angelini P – Coronary artery anomalies – current clinical issues. Definition, classifications, incidence, clinical relevance and treatment guidelines. Tex Heart Inst J 2002;29:271-278

? Coronary artery Variation vs Anomalies A broad spectrum of variations of which some may cause adverse effects Most of the coronary variations may have no clinical implications as can be proven by myocardial perfusion studies. The regional distribution of a coronary artery, rather than its absolute origin and characteristics.

Level of variables 1) Ostium 2) Size 3) Proximal course 4) Mid-course 5) Intramyocardial ramifications 6) Termination Anomalies without a shunt: 1. Abnormal number : 1/ 3/ 4 ostia 2. Anomalous origin: a) Outside SOV b) Independent origin from same sinus c) Opposite sinus d) Other artery 3. Myocardial bridge 4. Segmental stenosis/hypoplasia Anomalies with shunt: 1) Fistula 2) APOCA C. Aneurysms

A puzzling issue….. Proximal course of the LAD may be very different LCx may run over atrial or ventricular surface. An RCA that terminates in the AV groove well before the crux may not always be an obstruction: 7 – 10% (Grossman) Double ostia from the RCS All 3 arteries from a single sinus One single artery……………..and so on……

The most common coronary variation (Cleveland Clinic-1,26,000 patients) was separate ostia for LAD & LCX – 0.41% and 2nd commonest was LCX from RCS / RCA – 0.37% However, in another series of 1950 angiograms coronary anomalies were seen in 5.6% cases and split RCA (1.2%) was the commonest. 127,000 patients (Grossman) Angelina P. Coronary artery anomalies. Philadelphia, Lippincott Williams & Wilkins, 1999.

1) Ostium 2) Size 3) Proximal course Level of variables 1) Ostium 2) Size 3) Proximal course 4) Mid-course 5) Intra-myocardial ramifications 6) Termination MSCT with retrospective ECG gating is now considered the gold standard for characterization of coronary anomalies. Prompt a search for underlying CHDs 1) Shi H, Aschoff AJ, Brambs HJ. Multislice CT imaging of anomalous coronary arteries. Eur Radiol. 2004;14:2172-2182. 2) Memisoglu E, Hobikoglu G, Tepe MS. Congenital coronary anomalies in adults: Comparison of anatomic course visualized by catheter angiography and electron beam CT. Catheter Cardiovasc Interv. 2005;66:34-42.

Abnormal position of ostia Coronary orifice below the cuspal margin: - 10% RCS 15% LCS Coronaries above the sinotubular jn ~ 6% - leads to difficult cannulation, esp RCA with a high anterior ostium.

Abnormal number of coronary arteries Single coronary artery - 0.024%, usually benign D/d- 2 separate ostia from same sinus, atresia.. Course is important – in 25% a major branch crosses the infundibulum. 3 coronaries - 1) Separate origin of conus artery from RCS (36- 50%) 2) Absent LMCA with separate ostia for LAD & LCX 4 coronaries - case reports Dual LAD- 0.13 -1% (Morettin ,1976)

Absent LMCA ~0.4% - 1 ostia at the LCS/ 2 ostia in LCS/ 1 ostia in LCS & other RCS Increased incidence of Left dominance 6% incidence of bridging Not usually associated with CHDs Similar incidence of atherosclerosis Difficulty in selective cannulation Topaz et al. Absent left main coronary artery: angiographic findings in 83 patients with separate ostia of the left anterior descending and circumflex arteries at the left aortic sinus. Am Heart J.1991 Aug;122(2):447-52.

Shepherd’s-crook RCA ~5% Acute superiorly angled take-off of the RCA from the aorta. Difficult RCA lesion angioplasty Ethan Halpern. Cardiac CT . Functional anatomy.

Dual LAD (Duplication) ~0.13 - 1% of normal hearts Proximal LAD (LAD proper) bifurcates early into a short and long LAD -Type I : Short LAD in AIVS, Long LAD on prox AIVS, LV side, distal AIVS -Type II : Short LAD in AIVS, Long LAD on prox AIVS, RV side, distal AIVS -Type III: Short LAD in AIVS, Long LAD intra-myocardially in septum -Type IV: Very short LAD proper and short LAD, Long LAD from RCA Spindola-Franco H et al. Dual left anterior descending coronary artery: angiographic description of Important variants and surgical implications. Am Heart J 1983:105;445–55.

Coronary artery Ectasia 1 - 5% in angiographic series, more in males 20- 30 % are congenital Dialatation of a segment to at least 1.5times of the adjacent normal coronary artery.

Coronary venous anatomy Targeted drug delivery Retrograde cardioplegia administration Potential conduit to bypass cor. artery stenosis Stem cell delivery to the infarcted region Access to LA & LV myocardium for arrythmia mapping & ablation LV epicardial pacing in CRT

Coronary venous anatomy

THEBESIAN veins – Venae cordis minimae

Conventional coronary venous nomenclature Coronary sinus - Thebasian valve Anterior IV vein(Great cardiac vein) - Vieussens valves - Left marginal vein of LV - Postero-lateral LV vein Middle cardiac vein Small cardiac veins SEGMENTAL CLASSIFICATION The highly variable existence of the conventional veins calls for segmental classification (ant, lat, post, base, mid and apex -9 segments of the LV) of coronay veins for better epicardial localization of veins for interventional electrophiography purposes.

Segmental venous classification Thus 9 LV venous segments are derived which when added with the conventional classification gives the best comprehensive information to place the epicardial LV leads for CRT purposes

Retrograde coronary venography Lateral LV wall venous branches can be profiled by individualizing the different radiological views- considering the anterior IV vein and middle cardiac vein as reference points.

MDCT angiogram delineating coronary veins along with arteries Before venogram for better characterisation of coronary vein variations. However additional 60ml contrast and 9-11mSv exposure.

Coronary Angiographic Views Cardiac Cath 1st by Werner Forssman in 1929 1st contrast angiography by Chavez in 1947 CART 1st performed by F. Mason Sones in 1958 a high-resolution image-intensifier television system with digital cineangiographic capabilities. - Radiograph tube below and Image intensifier above (Flouroscopic imaging system with C-arm) - Physiologic monitoring system, sterile supplies, resuscitation equipment, Contrast injector (3-8ml/sec) and contrast media Xray generator, Xray tube , Image intensifier and detector, digital angio imaging. A higher angulation increases the radiation scatter. Fluoroscopy has only 1/5th rad exposure of cine angiography NCRPM guideline: not >3 rem per 3months.. Advised safe limit is 100mrem/week for cath lab personnel. Skin and thyroid- 15rem/year, gonads, eyes, bonemarrow- 5rem/yr Cxray= 3 -5 mRoentgen ( 1 R = 1 rad for skin, 1R= 4rad for bone due to more absorption) R= radiation exposure, Rad = radiation absorptioon) Rem= radiation equivalent dose in man. 1 rem= 1rad. 1SV= 1J/kg=1Gy 1gy=100rad 1Sv= 100rem 1mrem=10micSv

Information from a CAG: CAG helps visualization of the major epicardial arteries up to their 2nd and 3rd order branches - Coronary anatomy Characteristics and distribution of coronary stenosis Distal vessel size Intracoronary thrombus Index of coronary flow Mass of myocardium served Collateral vasculature Optimal injection rate: 7ml (2.1ml/s) for LCA and 4.8ml (1.7ml/s) for RCA

Pitfalls of CAG – A Lumenogram

Interpretation of the significance of a lumenogram Multiple projections from different angles, preferably orthogonal Knowledge of the normal calibre of major coronaries: LMCA: 4.5 ± 0.5 mm LAD: 3.7 ± 0.4 mm LCX : 3.5 ± 0.5 mm ( 4.2 mm if dominant) RCA: 3.9 ± 0.6 mm ( 2.8 mm if non-dominant) IVUS Functional studies : FFR

Mistakes in CAG interpretation Inadequate number of projections used Improper/inadequate contrast injection Super-selective injection Catheter induced vasospasm Coronary artery variations Myocardial bridges Total ostial occlusions Wire induced spasm (ACCORDION EFFECT) Accordion effect: A mechanical alteration in the geometry and curvature of the vessel due to straightening and shortening of the artery due to wire advancement.

Angiographic projections LAO and RAO views help furnish the true PA and lateral views of the heart D/A s - foreshortening - superimposition Cranial view: Image-intensifier tilted towards head Caudal view: Image-intensifier tilted towards the feet -however the optimal angiographic view varies with coronary anatomy, body habitus and location of lesion

Angiographic projections Kern MJ. Cardiac Catheterization Handbook. 5th edition,2011.

RAO and LAO projections

Optimal angiographic views for coronary segments Carlo Di Mario, Nilesh Sutaria. CORONARY ANGIOGRAPHY IN THE ANGIOPLASTY ERA: PROJECTIONS WITH A MEANING Heart 2005;91:968–976.

RAO- LCA When the LMCA, LAD, LCX have an initial leftward course the long axis of these arterial segments are projected away frm the image intensifier and prevent optimal visualisation in the RAO view.

RAO- RCA

Optimal angiographic views for coronary segments Carlo Di Mario, Nilesh Sutaria. CORONARY ANGIOGRAPHY IN THE ANGIOPLASTY ERA: PROJECTIONS WITH A MEANING Heart 2005;91:968–976.

Shallow RAO cranial - LCA

AP cranial - LCA

RAO cranial - RCA

Optimal angiographic views for coronary segments Carlo Di Mario, Nilesh Sutaria.CORONARY ANGIOGRAPHY IN THE ANGIOPLASTY ERA: PROJECTIONS WITH A MEANING Heart 2005;91:968–976.

RAO caudal - LCA

Optimal angiographic views for coronary segments Carlo Di Mario, Nilesh Sutaria.CORONARY ANGIOGRAPHY IN THE ANGIOPLASTY ERA: PROJECTIONS WITH A MEANING Heart 2005;91:968–976.

AP (Shallow RAO) caudal- LCA

Optimal angiographic views for coronary segments Carlo Di Mario, Nilesh Sutaria.CORONARY ANGIOGRAPHY IN THE ANGIOPLASTY ERA: PROJECTIONS WITH A MEANING Heart 2005;91:968–976.

LAO - LCA

LAO - RCA

Optimal angiographic views for coronary segments Carlo Di Mario, Nilesh Sutaria. CORONARY ANGIOGRAPHY IN THE ANGIOPLASTY ERA: PROJECTIONS WITH A MEANING Heart 2005;91:968–976.

LAO cranial - LCA Some overlap with LCX can be overcome by more 60 degree LAO tilt. However when the proximal LCA is superiorly directed it is not an optimal view- use LAO caudal

LAO cranial - RCA

Optimal angiographic views for coronary segments Carlo Di Mario, Nilesh Sutaria.CORONARY ANGIOGRAPHY IN THE ANGIOPLASTY ERA: PROJECTIONS WITH A MEANING Heart 2005;91:968–976.

LAO caudal (Spider view) - LCA Enhanced by maximal expiration as the heart becomes more horizontal

Optimal angiographic views for coronary segments Carlo Di Mario, Nilesh Sutaria.CORONARY ANGIOGRAPHY IN THE ANGIOPLASTY ERA: PROJECTIONS WITH A MEANING Heart 2005;91:968–976.

Lateral view Mid & distal LAD Proximal LCX Mid RCA LIMA graft to LAD

Optimal angiographic views for coronary segments There is no single magical projection that can be applied uniformly to all patients for visualizing a particular coronary atery According to Grossman: For LCA – RAO caudal and LAO caudal for LMCA and proc LAD in orthogonal & RAO cranial and LAO cranial for mid and distal LAD in orthogonal For RCA: LAO for proximal RCA and RAO cranial for distal, PDA, PLV and Lateral view for mid Carlo Di Mario, Nilesh Sutaria. CORONARY ANGIOGRAPHY IN THE ANGIOPLASTY ERA: PROJECTIONS WITH A MEANING Heart 2005;91:968–976.

Panoramic coronary angiography GIORGIO TOMMASINI et al. Panoramic Coronary Angiography. JACC 31(4),March 15, 1998:871–7

References Hurst’s The Heart 13th Edition Braunwalds Heart Disease 9th edition Grey’s Anatomy Kern’s Handbook of Interventional Catheterization Kjell C Nikus. Coronary angiography. Grossman’s Textbook of Cardiac Catheterization Carlo Di Mario, Nilesh Sutaria. CORONARY ANGIOGRAPHY IN THE ANGIOPLASTY ERA: PROJECTIONS WITH A MEANING Heart 2005;91:968–976 David M Fiss. Normal coronary anatomy and anatomic variations. Applied Radiology, Jan 2007. Horia Muresian. Coronary arterial anomalies and variations. MAEDICA. A journal of clinical Medicine,1(1), 2006. Singh et al. The coronary venous anatomy. A segmental approach to aid CRT 2005, 46(1), 68-74. Shilpa Bhimali et al. A STUDY OF VARIATIONS IN CORONARY ARTERIAL SYSTEM IN CADAVERIC HUMAN HEART. World Journal of Science and Technology 2011, 1(5): 30-35 ISSN: 2231 – 2587.

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