Final answer:
A left-dominant heart indicates that the left coronary artery is responsible for supplying the posterior descending artery. This anatomical configuration contrasts with a right-dominant heart, where the right coronary artery would supply the posterior descending artery.
Step-by-step explanation:
In terms of coronary circulation, the left coronary artery is responsible for distributing blood to the left side of the heart, including the left atrium and ventricle, and the interventricular septum. It also gives rise to the anterior interventricular artery (left anterior descending artery) and in some cases the circumflex artery, which may eventually provide branches that form anastomoses with the posterior descending artery.
The heart is known for its asymmetrical structure, with a larger left side compared to the right, correlating with the roles of the pulmonary and systemic circuits. A left-dominant coronary circulation is characterized by the left coronary artery or one of its branches, such as the circumflex artery, providing the blood supply for the posterior descending artery, which normally supplies the interventricular septum and portions of both ventricles. This contrasts with a right-dominant heart, where the right coronary artery would give rise to the posterior descending artery.