The Anatomy of the Posterior Interventricular Artery

The coronary arteries run along the surface of the heart and supply the heart muscle with blood. Usually, two main coronary arteries, the left and the right, arise from the base of the aorta and form a circle around the base of the heart.

A large coronary artery called the posterior interventricular artery, or posterior descending artery (PDA), runs lengthwise along the back of the heart, supplying blood to its posterior (bottom) portion.

Like the other coronary arteries, the posterior descending artery can be affected by coronary artery disease.

Anatomy

Structure

The heart is roughly cone-shaped, with a base (the wider part of the cone) and apex (the tip of the cone). There are four cardiac chambers: the smaller atria toward the base of the heart, and the larger ventricles toward the apex.

A groove that runs lengthwise along the heart, from the base to the apex, divides the right and left ventricles—this is called the interventricular groove, or sulcus. A groove that runs around the base of the heart divides the atria from the ventricles—this is called the atrioventricular groove.

The PDA is surrounded by fatty tissue (epicardial fat) and supplies blood to the bottom surface of the heart. Along its course, it gives off branches called septal perforators, which supply portions of the interventricular septum—a thick, muscular wall which divides the right and left ventricles.

At the cardiac apex, small branches of the PDA may meet branches of the large artery that supplies the front of the heart, the left anterior descending.

Location

The right and left main coronary arteries arise from the base of the aorta, from bulges called the coronary sinuses of Valsalva. The term “coronary” derives from the Latin for “crown,” and the two main coronary arteries encircle the base of the heart, along the atrioventricular groove, a bit like an incomplete crown.

Several large coronary artery branches arise from this crown, supplying blood to different portions of the heart. The major arteries that run along the interventricular groove are the left anterior descending artery and the posterior interventricular artery.

Anatomical Variations

Coronary artery anatomy varies a great deal from person to person. Most patients (about 60% to 85%) have a right-dominant circulation, in which the right coronary artery gives rise to the posterior descending artery. In people with a left-dominant circulation, the posterior descending artery arises from a large branch of the left coronary artery, the circumflex.

There are cases where both the left coronary artery and right coronary artery contribute to the posterior descending artery, a situation called codominant circulation.

The posterior descending artery arises near the crux cordis, where the atrioventricular groove meets the posterior interventricular sulcus. It travels along the sulcus, lengthwise along the cone, along the bottom of the heart.

Function

The posterior interventricular artery supplies blood to the heart’s posterior, or bottom, portion.

Clinical Significance

The coronary arteries can vary with respect to their origin, number, and course, and many variants have been described in medical literature. While many variants cause no symptoms, some may be significant.

The posterior interventricular artery may be very small in some patients. In this case, blood is supplied to the bottom of the heart via other branches of the right and left coronary arteries.

About 1% of patients have a split right coronary artery, in which the right coronary artery divides early and gives rise to two separate posterior descending arteries. This anomaly usually does not cause symptoms.

Surgery

The fact that there is so much variability in coronary artery anatomy is important in itself. Doctors performing a coronary intervention (such as angioplasty or stenting) or surgery (e.g., coronary artery bypass grafting) should be aware of potential variations so that unusual anatomy is not confused for disease.

For example, patients with left-dominant circulation tend to have a small right coronary artery, which may be confused for a blocked vessel. Surgeons performing a coronary artery bypass plan their surgeries with a detailed map of the patient’s coronary arteries, including any anatomic variations.

Like other coronary arteries, the posterior interventricular artery may be involved in coronary artery disease, in which atherosclerosis of the coronary arteries leads to an inadequate supply of blood to the heart muscle. Atherosclerosis occurs when there is a buildup of plaque—fatty deposits—in your arteries, leading to narrowing and hardening of the arteries.

Coronary artery disease is the leading cause of death in both developed and developing countries. It can lead to heart failure, arrhythmias, myocardial infarction, and other complications. In a myocardial infarction (heart attack), ruptured atherosclerotic plaque in a coronary artery cuts off the blood supply to the heart muscle.

Depending on coronary dominance, plaque in the right coronary artery or circumflex artery can cause a loss of blood supply to the posterior interventricular artery, resulting in ischemia to the bottom heart wall.