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=Coronary anatomy and imaging planes=
=Introduction and History=


==Aortic arch with its branches and internal mammary arteries==
Coronary angiography is a minimally invasive procedure to access the coronary circulation and blood filled chambers of the heart using a catheter. It is performed for both diagnostic and therapeutic purposes.


The aortic arch has three main branches. Coming from the heart the brachiocephalic trunk is the first. It gives rise to the right subclavian artery and the right common carotid artery. The next branches coming out of the aortic arch are the left common carotid and left subclavian arteries. Anatomic variations in these vessels can make coronary angiography via the radial artery more challenging than via the femoral artery. The Left and right internal mammary arteries start in the proximal part of both subclavian arteries and run down following the inner thoracic wall outside the pleural cavity.  
It has become such a common tool in diagnosing coronary artery disease, that it is hard to understand it’s relatively short history. Radner was the first researcher in 1945 to visualize the coronary arteries in humans, through a transsternal puncture <cite>Radner</cite>. In 1958 Sones at the Cleveland Clinic succeeded in injecting small amounts of contrast material directly in the coronary arteries<cite>Sones</cite>. In the late sixties Judkins developed the percutaneous transfemoral approach and used pre-bent catheters to cannulate the coronary ostia. In the seventies Charles Dotter and Andreas Gruntzig extended the catheterization to therapeutic uses. In the nineties, vascular acces via the radial artery became a realistic alternative.


 
== References ==
[[File:Aortic arch.gif|thumb|none|300px| Aortic arch and its branches]]
<biblio>
 
#Radner pmid=19023714
 
#Sones pmid=13915182
==Aortic root==
#Jukema Jukema JW, Vliegen HW, Bruschke AVG. Coronary angiography: principles, technique and interpretation. 1e druk, Leiden, the Netherlands, 2009. Chapter 1: 7
 
The aortic root starts proximal of the SinoTubular Junction (STJ) which seperates the aortic sinuses from the tubular part (ascending aorta) (Fig 1). The right coronary artery has its ostium in the right coronary cusp. The left coronary artery has its ostium in the left coronary cusp (Fig 2). Note in the long axis view that both coronary arteries start just beneath the STJ. Because the aortic valve is somewhat tilted in the coronal plane the proximal part of the Right Coronary Artery (RCA) often runs a more downward course than the Left Main Coronary Artery (LMCA) which runs more horizontally. This effect is more pronounced when the ascending aorta and root are dilated. In these patients engaging the right coronary ostium in coronary angiography can sometimes be more difficult and require different catheters.
 
 
[[File:Aortic root LA Image.jpg|thumb|none|400px|Fig 1: Long axis CT of aortic root]]
 
 
[[File:Aortic root sa.jpg|thumb|none|400px|Fig 2: Short axis CT of aortic root]]
 
 
==Coronary arteries==
 
The two main coronary trunks lie in two perpendicular planes (Fig 1); The Right Coronary Artery and Left Circumflex Artery (LCX) run in the atrioventricular groove. The Left Anterior Descending (LAD) or Ramus Descendens Anterior (RDA) and Right Posterior Descending (RDP) run in the interventricular groove in de plane of the interventricular septum. In the standard Right Anterior Oblique (RAO) 30 we are looking down the plane of the AV-valves and have the LAD and the IVS running form left to right on the screen (Fig 2). In the Left Anterior Oblique 45 (LAO) projection we will be looking directly onto the AV-plane.
 
 
[[File:699px-Heart_left_anterior_oblique_diagrams.svg.png|thumb|none|300px|Left anterior oblique view of the coronary arteries]]
 
 
[[File:1000px-Heart right anterior oblique diagrams.svg.png|thumb|none|300px|Right anterior oblique view of the coronary arteries]]
 
 
===Right Coronary Artery===
 
The right coronary artery has its ostium just beneath the Sinotubular junction in the Right Coronary Cusp (RCC). It gives rise to the conus branch which supplies the Right Ventricular Outflow Tract. In about 60% of the cases the SA node is supplied by a proximal branch arising from the RCA (The other 40% via a left atrial branch comming from the RCX). The RCA follows the AV-groove giving rise to one or more Marginal Branches (which supply the RV free wall). Continuing in the AV-groove in the most common anatomical form it gives rise to a right posterior descending (RDP; supplies the inferior septum) artery and a  right posterolateral branch (RPL) (Fig 1 and 3). At the junction with the RDP a small side branch supplies the AV-node (AV-nodal artery)
Several anatomical variants are common. Both the PL- and DP-branches can also be sidebranches from the LCX. A left dominant circulation is present when the LCX also supplies the RDP.  In a left dominant circulation the right coronary artery is usually small. A balanced system is present when the LCX supplies a parallel descending branch also supplying the inferior septum.  Left dominant circulation is seen in about 8% of the patients.
 
 
* [[Left Coronary Artery - Right Dominant]]
* [[Left Coronary Artery - Left Dominant]]
 
* [[Right Coronary Artery - Right Dominant]]
* [[Right Coronary Artery - Left Dominant]]
===Left Coronary Artery===
 
The Left Coronary Artery (LCA) arises from the superior portion of the of the left aortic sinus just below the sinotubular junction. Typically it begins as a Left Main (LMCA) for about 0 to 10mm before giving rise to the LAD and LCX. In less than 1% there is no LMCA and the LAD and LCX originate directly from the left sinus of valsalva; so-called seperate ostia.  The left main can also give rise to intermediate or anterolateral (AL) branches that originate from the left main inbetween the LAD and LCX.
 
* [[Separate ostia]]
* [[Intermediate branch]]
===Left anterior descending===
 
The LAD runs on the epicardial surface in the interventricular groove towards the apex. The major branches coming from the LAD are the septal and diagonal branches. The septals pass into the interventricular septum. The diagonals run anterolateral on the epicardial surface. There is a wide variability in both the number and size of septal and diagonal branches.
 
===Ramus Circumflex===
 
The LCX follows the posterior AV-groove giving rise to obtuse marginal branches supplying the posterolateral wall of the heart. As described before in some cases the LCX also supplies the sinus node via a left atrial branch. In left dominant circulation the circumflex supplies the inferior interventricular septum via a descendens posterior artery.
 
 
[[File:Coronary_anatomy_AHA.svg|thumb|none|500px| Coronary anatomy with AHA classification <cite>AHA</cite>]]
 
* [[Left ventriculogram]]
 
==References==
<biblio>
<biblio>
#AHA pmid=1116248
</biblio>
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