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It is said that the coronary artery that gives the posterior descending artery(PDA) determines if the heart is right dominant(most cases) or left dominant. Is there any reason to this? Why PDA?

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  • $\begingroup$ Where/ By whom is that said? Could you please provide a reference? $\endgroup$ – Arsak Apr 23 at 13:55
  • $\begingroup$ source, please... $\endgroup$ – cell0 Apr 23 at 20:07
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This is purely an anatomical definition: right dominant is defined as coronary circulation where the PDA (posterior descending artery) is a branch of the RCA (right coronary artery) and left dominant is defined as coronary circulation where the PDA is a branch of the LCX (left circumflex artery). The Wikipedia article on coronary circulation is a reasonable reference for this question.

There's nothing else special about the statement "dominant" and it doesn't have any other importance for cardiac function, except that someone who is left dominant would have more serious issues if there is a blockage in their left main or LCX.

Typical human coronary artery anatomy consists of two ostia off the aorta, right and left. The "left main" branches fairly early on into the LAD (left anterior descending) artery, which follows the septum between left and right ventricles down the anterior side, and the LCX, which follows the 'top' of the left ventricle counter-clockwise (if looking down at the top of heart and rotating the heart so the atria are on top; in an actual human heart the atria actually point towards the midline a bit more than other species). The RCA travels in roughly mirror fashion, following the 'top' of the right ventricle in clockwise fashion. The RCA and LCX nearly meet on the other side of the heart, at the posterior septum.

In a majority of people, the RCA continues and follows the septum down to the apex (kind of like the LAD but on the opposite side). In a non-negligible minority, the supply of the posterior descending artery is either shared by RCA and LCX or is completely supplied by the LCX.

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  • $\begingroup$ Thank you for the answer. Could you elaborate on 'someone who is left dominant would have more serious issues if there is a blockage in their left main or LCX' Please? For wouldn't someone right dominant have equally serious problem with a blockage in left main artery? $\endgroup$ – ADP Apr 24 at 14:16
  • $\begingroup$ @ADP Of course a complete left main blockage is pretty much fatal already, but I meant it just as to a matter of degree: the more of the heart is supplied by that vessel the more severe a blockage is. The same goes on the other side: someone who is right-dominant would have more severe impacts from a RCA blockage than someone who is left-dominant. $\endgroup$ – Bryan Krause Apr 24 at 14:25

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