Expansion
Right sinus gives the right coronary artery, left sinus gives the left, the posterior sinus is non-coronary
Expansion
Three dilatations sit above the aortic valve cusps:
- Right (anterior) sinus - gives the right coronary artery
- Left sinus - gives the left coronary artery
- Posterior sinus - non-coronary
The sinuses have two functions. They prevent the cusps from occluding the coronary ostia when the valve opens, and the eddy currents within them help close the cusps at the start of diastole.
Coronary filling occurs almost entirely in diastole, when the aortic valve shuts and pressure in the sinuses is maintained by elastic recoil of the aorta. This is why tachycardia, by shortening diastole, worsens myocardial ischaemia.