Posterior Descending Artery as a Continuity from the Left Anterior Descending Artery

Coronary angiogram revealed a posterior descending artery (PDA) as a continuity from the left anterior descending artery (LAD) following a course onto the posterior interventricular groove.

Eftihia S. Hamodraka, MD, Konstantinos Paravolidakis, MD, Thomas Apostolou, MD

The patient was a 44-year-old woman who was admitted to the hospital due to chest pain at rest. Two days later, the patient underwent a coronary angiogram. The angiogram revealed a left anterior descending artery (LAD) following a normal course along the anterior interventricular groove and terminating as a posterior descending artery (PDA) into the posterior interventricular septum (Figure 1). The right coronary artery was a small artery, and the circumflex artery followed a normal course. There were no atherosclerotic lesions in any of the above-mentioned arteries.
The posterior descending artery normally arises from the right coronary artery (RCA) in approximately 85% of people; however, in 10–15% of people, it arises from the left circumflex artery.1 There are few reported cases of the RCA arising from the LAD without an identifiable right coronary ostium.2 Another case reported the PDA arising from an aberrant branch of the LAD3 without the intraseptal course described in the case here. To our knowledge, this is the first case of a LAD continuing to the PDA along the posterior interventricular groove, supplying both the anterior and posterior interventricular septum with blood. The clinical importance of this variation is that if the LAD occluded, a severe infarction of the septum and inferior wall would be expected to develop. Such a risk is something an invasive cardiologist must be aware of whenever performing an angiogram on patients who have suffered a large infarction involving both the inferior and anteroseptal walls.

OIT studentsays: October 6.2011 at 11:53 am

I have a 2004 edition of the Atlas of Human Anatomy by Frank H. Netter, M.D. that shows the abarrant branch of the LAD you discuss in your 2005 article as a standard variation. In this variation I do not believe the artery would have descending flow, rather it would be ascending. "Posterior interventricular (posterior descending) branch absent. Area supplied chiefly by elongated anterior interventricular (left anterior descending) branch curving around apex" (Netter, 2004).

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