From the Guidelines
The myocardial wall is perfused by the coronary arteries, specifically the left and right coronary arteries, which branch from the aorta, and the intermediate artery, also known as the ramus intermedius, supplies blood to the anterolateral wall of the left ventricle when present. The coronary arteries further divide into smaller vessels, including intermediate arteries. The intermediate artery arises between the left anterior descending artery and the left circumflex artery from the left main coronary artery. When present, this intermediate artery supplies blood to the anterolateral wall of the left ventricle, perfusing this portion of the myocardium. This anatomical variant occurs in approximately 15-30% of people, as noted in various studies 1.
The presence of an intermediate artery is significant because it provides an additional blood supply route to the myocardium, which can be protective in cases of coronary artery disease affecting other vessels. However, if the intermediate artery itself becomes occluded, it can lead to myocardial infarction in the anterolateral region of the left ventricle. Recent guidelines, such as the 2021 ACC/AHA/SCAI guideline for coronary artery revascularization 1, emphasize the importance of understanding coronary anatomy in the management of patients with acute myocardial infarction.
Key points to consider include:
- The intermediate artery is a variant branch that can supply blood to the anterolateral wall of the left ventricle.
- The presence of an intermediate artery can provide additional protection against coronary artery disease.
- Occlusion of the intermediate artery can lead to myocardial infarction in the anterolateral region of the left ventricle.
- Understanding coronary anatomy is crucial in the management of patients with acute myocardial infarction, as highlighted by recent guidelines 1.
From the Research
Myocardial Wall Perfusion
The myocardial wall is perfused by various coronary arteries, including the left anterior descending (LAD), right coronary artery (RCA), and left circumflex (LCX) arteries.
- The LAD artery perfuses the anterior, anteroseptal, and apical segments of the left ventricle 2.
- The RCA artery perfuses the inferior and inferolateral segments, but no segment can be exclusively attributed to the RCA 2.
- The LCX artery perfuses the basal anterolateral segment, and may also perfuse the mid-anterolateral, basal inferior, basal inferolateral, mid-inferior, and mid-inferolateral segments 2.
Intermediate Artery Perfusion
An intermediate artery, also known as a diagonal artery, typically arises from the LAD and perfuses the anterior and anterolateral segments of the left ventricle.
- The intermediate artery may perfuse segments that are also perfused by the LAD or LCX arteries 2.
- The specific segments perfused by an intermediate artery can vary depending on the individual's coronary anatomy.
Clinical Relevance
Understanding the perfusion of the myocardial wall by different coronary arteries, including intermediate arteries, is important for diagnosing and treating coronary artery disease.