Left anterior descending artery (LAD)
The left anterior descending artery, preferably known as the anterior interventricular artery (AIV), is the continuing branch of the left coronary artery. It is located subepicardially within the anterior and inferior interventricular sulci of the heart.
The artery gives off conal, anterior ventricular and interventricular septal branches. They contribute mainly to the blood supply of the anterior surface of the left ventricle and the distal two thirds of the interventricular septum, both anterior and inferior. By supplying large areas of the heart with blood, an occlusion of the AIV can quickly lead to an extensive heart attack and death. Therefore, it is colloquially known as the widow maker artery.
This article will discuss the anatomy and function of the anterior interventricular artery.
|Origin||Left coronary artery|
|Branches||Conal, anterior ventricular (right, left), interventricular septal (anterior, inferior)|
|Supply||Anterior surface of left ventricle, distal two thirds of anterior and inferior interventricular septum|
Origin and course
The AIV stems from the left coronary artery at the superior end of the anterior interventricular sulcus. It courses obliquely and anteroinferiorly along the anterior surface of the heart towards its apex, within the anterior interventricular sulcus. The AIV curves around the apex of the heart and continues superiorly along the inferior surface of the heart, within the inferior interventricular sulcus. The artery ends approximately halfway along the inferior surface by anastomosing with the inferior interventricular branch (a.k.a posterior interventricular/posterior descending branch) of the right coronary artery.
Within the anterior interventricular sulcus, the AIV is accompanied on the right side by the anterior interventricular vein. This represents the first part of the great cardiac vein.
Branches and supply
The AIV has several branches:
- The conal branch is a small branch which supplies the left aspect of the conus arteriosus, anastomosing with the larger conus artery of the right coronary artery.
- Anterior ventricular branches, which are divided into right and left. The right anterior ventricular branches are small, supplying a small part of the anterior surface of the right ventricle directly adjacent to the anterior interventricular sulcus. The left anterior ventricular branches are more significant. They extend diagonally along the entire anterior surface of the left ventricle, supplying it with oxygenated blood. The left anterior ventricular branch can give off up to seven or eight diagonal branches (D1-D7/D8)
- Interventricular septal branches, which are divided into anterior and inferior. The anterior interventricular septal branches supply the anterior two thirds of the interventricular septum and the atrioventricular bundle. The inferior interventricular septal branches supply the distal third of the inferior interventricular septum.
Master the branches of the coronary arteries, including the AIV, using the articles, videos, quizzes and illustrations in the following study unit.
The extensive cardiac blood supply provided by the AIV can result in a life threatening situation during an occlusive event. As a result, the artery is commonly known as the widow maker artery. Prompt recognition of an occlusion of the AIV is extremely important. Electrocardiogram (ECG) findings associated with such an event include ST elevation and pathological Q wave formation in the V1-V4 precordial leads, which correspond to the anterior and septal territories of the heart. These changes are mirrored by a reciprocal ST segment depression in the inferior leads (II, III, aVF).
In case of an atypical presentation of an AIV occlusion, Wellen’s syndrome should be searched for. This represents one of the earliest signs of such a specific occlusion. It is characterised by symmetrical, deep or biphasic T waves in leads V-V6 during pain free periods in a patient with recent chest pain, no elevation of cardiac enzymes, no pathological Q waves and no significant ST segment elevations.