Origins of the coronary arteries and their significance

Abstract

Objective: To describe the normal and variant anatomy of the coronary artery ostia in Indian subjects.

Introduction: Anomalous coronary origins may cause potentially dangerous symptoms, and even sudden death during strenuous activity. A cadaveric study in an unsuspected population provides a basis for understanding the normal variants, which may facilitate determination of the prevalence of anomalies and evaluation of the value of screening for such anomalies.

Methods: One hundred and five heart specimens were dissected. The number of ostia and their positions within the respective sinuses were observed. Vertical and circumferential deviations of the ostia were observed. The heights of the cusps and the ostia from the bottom of the sinus were measured.

Results: No openings were present in the pulmonary artery or the non-coronary sinus. The number of openings in the aortic sinuses varied from 2-5 in the present series; multiple ostia were mostly seen in the anterior sinus. The majority of the ostia lay below the sinutubular ridge (89%) and at or above the level of the upper margin of the cusps (84%). Left ostial openings were mainly centrally located (80%), whereas the right coronary ostia were often shifted towards the right posterior aortic sinus (59%).

Discussion: The preferential location of the ostia was within the sinus and above the cusps, but below the sinutubular ridge. On occasion, normal variants like multiple ostia, vertical or circumferential shift in the position, and slit-like ostia may create confusion in interpreting the images and pose a difficulty during procedures like angiography, angioplasty, and coronary artery bypass grafting.

Keywords: Aortic cusps; Aortic sinuses; Commissures; Coronary ostium; Sinutubular ridge.

Figure 1a

Schematic diagram of an opened aortic orifice showing: 1 - sinutubular ridge; 2 - commissures; 3 - coronary ostium; 4 - ventriculoarterial junction; 5 - attached margin of the aortic cusp; 6 - free upper margin of the aortic cusp. Arrows a and b indicate the heights of the ostium and the cusp from the bottom of the sinus, respectively

Figure 1b

The aortic orifice viewed from the arterial aspect in order to show the aortic sinuses; ‘aas’ indicates the right coronary artery (RC); ‘lps’ indicates the left coronary artery (LC), and ‘rps’ indicates the non-coronary sinus (NC). Commissures (I, II, III) can be seen. Arrows indicate the circumferential deviation of the ostia towards the commissures

Figure 2

Multiple ostia (arrows) in the anterior aortic sinus (aas). The left posterior sinus (lps) shows separate ostia (arrows) for the left anterior descending and the left circumflex arteries

Figure 3

The left coronary ostium (arrow a) in the left posterior sinus (lps). The sinutubular ridge is arched to accommodate the ostium within the sinus. The right coronary ostium is present at the ridge (arrow b)

Figure 4

The left coronary ostium (arrow) above the level of the sinutubular ridge

Figure 5

The right coronary ostium below the level of upper margin of the cusp (arrow a) in the anterior aortic sinus (aas). A slit-like ostium (arrow-b) of the left coronary artery is also seen in the left posterior sinus (lps)

Figure 6

The circumferential deviation of the right coronary ostium (arrow a) towards Commissure I. The left coronary ostium is similar to a horizontal slit. The margin of the slit has been lifted and the lower margin is at arrow b. Aas - anterior aortic sinus; lps - left posterior sinus