Are there other intramyocardial vessels beyond septal branches?

Intramyocardial Vessels Beyond Septal Branches

Yes, there are several other intramyocardial vessels beyond septal branches that supply the myocardium, including diagonal branches, obtuse marginal branches, and posterolateral branches that can penetrate and course within the myocardium.

Types of Intramyocardial Vessels

1. Septal Perforator Vessels

• Anterior septal perforators: Originate from the LAD artery and supply the interventricular septum 1
• Posterior septal perforators: Originate from the posterior descending artery (PDA) and supply the inferior portion of the interventricular septum 1
• Right superior septal artery (RSSA): Originates from the proximal right coronary artery or directly from the right aortic sinus in about 27% of people 2

2. Diagonal Branch Vessels

• Diagonal branches: First, second, and third diagonal branches originate from the LAD artery and supply the anterolateral wall of the left ventricle 1
• These branches can have intramyocardial courses, particularly their distal segments and lateral branches 1

3. Obtuse Marginal Vessels

• Obtuse marginal branches: First, second, and third obtuse marginal branches originate from the left circumflex artery and supply the lateral wall of the left ventricle 1
• These branches frequently have intramyocardial segments, especially in their distal portions 1

4. Posterolateral Branches

• Posterolateral branches: Originate from either the right coronary artery in right-dominant circulation or from the left circumflex in left-dominant circulation 1, 3
• These vessels supply the posterolateral wall of the left ventricle and can have intramyocardial courses 1

Clinical Significance of Intramyocardial Vessels

Myocardial Blood Supply

• Intramyocardial vessels are crucial for adequate myocardial perfusion, particularly during increased oxygen demand 1
• The distribution of these vessels correlates with ECG findings during myocardial infarction 1

Collateral Circulation

• Intramyocardial vessels can form important collateral channels during coronary occlusion 4
• Retrograde flow in septal branches and other intramyocardial vessels can be detected by transthoracic Doppler echocardiography in patients with occluded coronary arteries 4

Interventional Considerations

• During septal reduction therapy for hypertrophic cardiomyopathy, the variability of septal blood supply is important 1
• Myocardial contrast echocardiography is essential prior to alcohol septal ablation to ensure proper localization 1
• The fixed anatomic distribution of septal perforator arteries limits the flexibility of alcohol ablation compared to surgical myectomy 1

Anatomical Variations

Coronary Dominance Impact

• In right-dominant circulation (70-80% of population), the PDA and posterolateral branches arise from the right coronary artery 3
• In left-dominant circulation (8-10%), these vessels arise from the left circumflex artery 3
• In co-dominant circulation (10-12%), the PDA comes from the right coronary artery while the posterolateral branches come from the left circumflex 3

Right Superior Septal Artery Variations

• The RSSA can originate from three different locations: proximal right coronary artery (most common), right coronary ostial area, or directly from the floor of the right aortic sinus (rare) 2
• The length of the RSSA varies from less than 10mm to up to 36mm in some cases 2

Clinical Applications

Diagnostic Imaging

• Coronary angiography and CT angiography can identify the major epicardial vessels but may miss smaller intramyocardial branches 3
• Echocardiography can detect flow in intramyocardial vessels, which is useful for identifying occluded coronary arteries 4

Therapeutic Considerations

• Understanding the distribution of intramyocardial vessels is crucial for planning revascularization procedures 5
• The small diameter (approximately 1mm) of many intramyocardial vessels limits their direct use in revascularization 5
• Patients lacking certain intramyocardial branches (such as the right superior septal artery) may be at risk for larger infarctions if the main supplying artery becomes occluded 6

In summary, the myocardium is supplied by a complex network of vessels beyond just septal branches, including diagonal branches, obtuse marginal branches, and posterolateral branches that can have intramyocardial courses. Understanding this vascular anatomy is essential for accurate diagnosis and effective treatment of coronary artery disease and other cardiac conditions.