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Second diagonal branch (D2) of LAD

The second diagonal branch (D2) is a major oblique branch of the left anterior descending (LAD) artery, arising distal to the first diagonal branch (D1). It typically courses laterally and superiorly over the anterolateral surface of the left ventricle, supplying the anterolateral free wall.

Diagonal branches (D1, D2, and occasionally more) vary in number, size, and course, but usually two prominent diagonals are seen, with D2 being smaller than D1 in most individuals. However, in some cases, D2 may be dominant, making it clinically significant. These branches are frequently considered in percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG), as they provide critical perfusion to the anterolateral left ventricular myocardium.

Synonyms

  • D2 branch of LAD

  • Second diagonal artery

  • Lateral diagonal branch

Function

  • Supplies arterial blood to the anterolateral free wall of the left ventricle

  • Contributes to collateral perfusion with branches of the circumflex artery

  • Plays a role in maintaining contractility and perfusion of the lateral left ventricle

  • Clinically relevant in myocardial ischemia, PCI, and CABG planning

Branches

  • Typically a terminal branch without named subdivisions

  • May form small collaterals with marginal branches of the left circumflex artery

MRI Appearance

T1-weighted images (non-contrast):

  • D2 lumen appears as a signal void (black) due to blood flow

  • Surrounded by hypointense vessel wall and epicardial fat providing contrast

T2-weighted images:

  • Flow void persists

  • Myocardial edema or infarction in D2 territory appears as hyperintensity in the anterolateral LV wall

STIR (Short Tau Inversion Recovery):

  • Fat suppression improves visualization of myocardial edema in D2 territory

  • Acute ischemia or myocarditis in the anterolateral wall appears bright hyperintense

T1 Post-Contrast (Gadolinium-enhanced):

  • Vessel lumen enhances brightly

  • Late gadolinium enhancement (LGE) demonstrates ischemic infarcts or fibrosis in D2-supplied myocardium

MRI Non-Contrast Cardiac-Gated 3D Coronary MRA:

  • Depicts D2 as a bright, oblique vessel arising from mid-to-distal LAD

  • Visualizes its origin, course, and perfusion territory without contrast

  • Useful in assessing anomalous course or pre-intervention planning in patients unable to receive contrast

CT Appearance

Non-contrast CT (Calcium Scoring):

  • Calcified plaques in the LAD–D2 junction appear as hyperdense foci

  • Contributes to total Agatston calcium score

CT Coronary Angiography (CCTA):

  • High-resolution visualization of D2 origin, course, and perfusion territory

  • Demonstrates stenosis, occlusion, calcified/non-calcified plaques, and anomalous course

  • Multiplanar and 3D reconstructions allow precise assessment for PCI or CABG graft placement

  • Helpful in risk stratification of lateral LV ischemia

MRI image

Second diagonal branch (D2) of LAD mri axial

CT image

Second diagonal branch (D2) of LAD anantomy CT axial image -img-00000-00000