cardiac wall segments | left ventricular segments diagram

The heart, a remarkable muscular pump, is responsible for circulating life-sustaining blood throughout the body. Its complex structure and function are critical for overall health. Understanding the anatomy of the left ventricle (LV), the heart's main pumping chamber, is paramount in diagnosing and managing various cardiac conditions. This understanding relies heavily on the concept of cardiac wall segments, a standardized method for dividing the LV into distinct regions, allowing for precise localization and assessment of myocardial function. This article provides a comprehensive overview of cardiac wall segments, focusing on the 17-segment model of the left ventricle, their clinical significance, and methods for their evaluation.

Why Divide the Left Ventricle into Segments?

The concept of dividing the left ventricle into segments serves several crucial purposes:

* Standardization: It provides a universally accepted nomenclature for describing regional myocardial abnormalities. This ensures clear communication among clinicians, radiologists, and other healthcare professionals.

* Localization: Precisely identifying the location of ischemia, infarction, or other pathology is essential for diagnosis, treatment planning, and prognosis. Segmental analysis allows for accurate localization of wall motion abnormalities or perfusion defects.cardiac wall segments

* Quantification: Segmental analysis facilitates the quantification of the extent and severity of myocardial dysfunction. This is important for tracking disease progression and evaluating the effectiveness of interventions.

* Correlation with Coronary Arteries: Specific segments of the LV are typically supplied by particular coronary arteries. Segmental analysis can help infer which coronary artery is likely affected in cases of ischemia or infarction.

* Image Interpretation: By having a standardized segmentation, it makes image interpretation more consistent, reproducible, and less subjective.

The 17-Segment Model of the Left Ventricle: A Detailed Look

The most widely used model for describing left ventricular segments is the 17-segment model, recommended by the American Heart Association (AHA). This model provides a detailed and comprehensive representation of the LV, facilitating accurate assessment of regional myocardial function. The 17 segments are derived from three short-axis slices (basal, mid-cavity, and apical) and a single long-axis slice (apical cap).

1. Short-Axis Slices:

The short-axis slices are obtained perpendicular to the long axis of the left ventricle, providing a cross-sectional view. These slices are typically acquired using cardiac imaging techniques such as echocardiography, cardiac MRI, or SPECT.

* Basal Level (Segments 1-6): The basal level is located at the base of the left ventricle, just below the mitral valve annulus. This level is divided into six segments:

* Anterior (Segment 1): The anterior segment is located on the anterior wall of the LV.

* Antero-septal (Segment 2): This segment lies between the anterior and septal walls.

* Infero-septal (Segment 3): Located between the inferior and septal walls.

* Inferior (Segment 4): The inferior segment corresponds to the inferior wall of the LV.

* Infero-lateral (Segment 5): This segment lies between the inferior and lateral walls.

* Antero-lateral (Segment 6): Located between the anterior and lateral walls.

* Mid-Cavity Level (Segments 7-12): The mid-cavity level is positioned halfway between the base and apex of the left ventricle. Similar to the basal level, it is also divided into six segments:

* Anterior (Segment 7): The anterior segment is located on the anterior wall of the LV.

* Antero-septal (Segment 8): This segment lies between the anterior and septal walls.

* Infero-septal (Segment 9): Located between the inferior and septal walls.

* Inferior (Segment 10): The inferior segment corresponds to the inferior wall of the LV.

* Infero-lateral (Segment 11): This segment lies between the inferior and lateral walls.

* Antero-lateral (Segment 12): Located between the anterior and lateral walls.

* Apical Level (Segments 13-16): The apical level is located at the apex of the left ventricle. This level is divided into four segments:

* Anterior (Segment 13): The anterior segment is located on the anterior wall of the LV.

* Septal (Segment 14): This segment corresponds to the septal wall of the LV at the apex.

* Inferior (Segment 15): The inferior segment is located on the inferior wall of the LV.

* Lateral (Segment 16): This segment corresponds to the lateral wall of the LV at the apex.

2. Apical Cap (Segment 17):

The apical cap represents the very tip of the left ventricle. This segment is not visible on the short-axis slices and is best visualized on long-axis views.

Visualizing and Interpreting Cardiac Wall Segments