Surgical anatomy of the coronary arteries
The coronary arteries branch off from the aortic root, specifically from the left and right aortic sinuses. These sinuses are formed by the cusps of the aortic valve: left, right, and non-coronary. The left coronary artery originates from the left coronary cusp, and the right coronary artery from the right.
Myocardial blood supply occurs predominantly during diastole. When the aortic valve closes, the blood ejected into the ascending aorta moves retrogradely and enters the coronary arteries. Additionally, the myocardial relaxation mechanism operates: during diastole, the coronary arteries are uncompressed and freely allow blood to pass.
- The left main coronary artery trunk (length 10–40 mm) divides into the anterior interventricular (anterior descending) artery and the circumflex artery.
- The anterior descending artery gives rise to diagonal branches (up to 6) and septal branches (up to 6).
- The diagonal branches supply the anterolateral wall of the left ventricle, and the septal branches supply the anterior two-thirds of the interventricular septum.
- The first septal branch supplies the muscle of Lancisi in the right ventricular outflow tract.
- The circumflex artery gives off obtuse marginal branches (first and second order) that supply the lateral wall of the left ventricle, including the anterolateral papillary muscle of the mitral valve.
- In 30% of cases, an intermediate (diagonal) artery originates between the anterior descending and circumflex arteries.
The right coronary artery gives off branches to the sinuatrial node, the conus artery, the AV nodal branch, and the acute marginal artery. The key branches for further clinical practice are the posterior interventricular artery and the posterior lateral branch, which supplies the posterior wall of the left ventricle. Knowledge of coronary anatomy is particularly important when planning heart valve surgeries.
Coronary angiography: indications and contraindications
Following positive results from an exercise ECG or stress echocardiography, the patient undergoes coronary angiography. Main indications:
- chronic stable angina;
- acute coronary syndrome (unstable angina, ST-elevation myocardial infarction, non-ST-elevation myocardial infarction);
- positive exercise stress test (e.g., ischemic ECG changes during a treadmill test);
- age over 40 with a history suggestive of coronary artery disease, prior to valve replacement — for potential simultaneous bypass surgery and valve replacement;
- post-successful resuscitation from cardiac arrest (as specified in clinical guidelines).
Relative contraindications include acute type A aortic dissection, infective endocarditis of the aortic valve with vegetations (risk of vegetation detachment and stroke during catheter advancement), active infection, decompensated heart failure with pulmonary edema, and severe renal dysfunction. An absolute contraindication is patient refusal of the procedure.
Access sites and complications of coronary angiography
Two main access sites are used for coronary angiography: the radial artery and the femoral artery.
Prior to radial access, the Allen test is performed: the radial and ulnar arteries are compressed, and then the ulnar artery is released. If the hand flushes pink within 10 seconds, the test is considered positive and radial artery access is safe — otherwise, hand ischemia may occur.
Femoral access is performed via palpation and puncture of the femoral artery.
Possible complications:
- local vascular complications (arterial rupture, bleeding, aneurysm, vascular spasm);
- contrast-induced nephropathy;
- cardiac tamponade due to perforation of the aorta or a coronary artery;
- coronary artery dissection (rupture) with false lumen formation;
- detachment of a guidewire fragment;
- cerebrovascular accident, myocardial infarction, mortality.
According to current guidelines, radial access is preferred over femoral access: a pressure bandage for 12 hours is sufficient after the procedure, and the patient is active and can be discharged the next day. Femoral access requires prolonged immobilization (more than 12 hours, sometimes 24 hours) and often urinary catheterization.
Choice of revascularization method: bypass surgery vs. stenting
Following coronary angiography, the treatment method is chosen: coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI), i.e., stenting.
- Single-vessel disease without proximal stenosis of the anterior descending artery — PCI is preferred.
- Single-vessel disease with proximal stenosis of the anterior descending artery — both methods are viable (PCI or CABG).
- Two-vessel disease without proximal stenosis — PCI is the method of choice.
- Two-vessel disease with proximal stenosis of the anterior descending artery — CABG is preferred.
- Left main coronary artery disease — bypass surgery is preferred due to the anatomical complexities of bifurcation stenting of the main trunk.
- Three-vessel disease, especially with a SYNTAX score greater than 22, as well as in diabetes mellitus — CABG is the method of choice.
The SYNTAX score is an anatomical grading tool to assess the severity of coronary artery disease, taking into account the type of circulation, dominant artery, affected segments, diameter and length of stenosis, presence of bifurcations and trifurcations, tortuosity, calcification, thrombosis, and diffuse lesions. The higher the score, the higher the likelihood that bypass surgery will be chosen.
Assessment of stenosis grade and blood flow
Stenosis is considered significant when vessel lumen narrowing exceeds 50%, critical when exceeding 70%, and occlusion is diagnosed at 90% or more (complete closure of the lumen).
To refine the treatment strategy, fractional flow reserve (FFR) is measured — determining the pressure before and after the stenotic lesion. Normally, the value is 1.0; a value below 0.8 indicates functionally significant ischemia and may alter the treatment strategy.
The degree of coronary blood flow is assessed using the TIMI classification:
- Grade 0 — absence of blood flow;
- Grade 1 — minimal blood flow, incomplete opacification of the distal bed;
- Grade 2 — sluggish filling of the distal bed;
- Grade 3 — normal antegrade flow with rapid opacification.
Stenting technique
Stenting is the placement via a guidewire of a metal scaffold (stent), which is expanded by a balloon inside the narrowed vessel to restore blood flow.
There are two main types of stents:
- bare-metal stents (BMS) — used previously;
- drug-eluting stents (DES) — recommended for all patients undergoing PCI regardless of clinical scenario (Class I, Level of Evidence A).
Radial access for PCI also holds a Class I, Level of Evidence A recommendation. Following stenting of one or two coronary arteries, the patient takes aspirin for life, and additionally receives a P2Y12 inhibitor (most commonly clopidogrel) for 12 months in the absence of contraindications and bleeding — this is dual antiplatelet therapy with a Class I, Level of Evidence A recommendation.
Key points
- The left coronary artery divides into the anterior descending and circumflex branches, supplying most of the heart.
- The right coronary artery gives off the posterior interventricular and posterior lateral branches.
- Coronary angiography is indicated in stable angina, acute coronary syndrome, and prior to valve replacement in patients over 40 years of age.
- Patient refusal is an absolute contraindication to coronary angiography.
- Radial access is preferred over femoral access in terms of safety and recovery time.
- The choice between bypass surgery and stenting depends on the lesion location, number of vessels involved, and the SYNTAX score.
- Drug-eluting stents are recommended for all patients undergoing PCI.
- Following stenting, dual antiplatelet therapy with aspirin and clopidogrel is prescribed for 12 months.