Left Ventricular Outflow: Blood Flow Through the Aortic Valve to Systemic Circulation

Systemic Arterial Blood Flow from the Left Ventricle

Oxygenated blood ejection pathway:

1. Left ventricle systole: Pressure > aortic diastolic → aortic valve opens.
2. Ascending aorta: 5 cm; gives off right and left coronary arteries (only branches of ascending aorta).
3. Aortic arch: Curves posteriorly/left. Three branches (proximal to distal):
   • Brachiocephalic trunk → right subclavian + right common carotid.
   • Left common carotid artery.
   • Left subclavian artery.
4. Descending (thoracic) aorta: Posterior mediastinum → intercostal, bronchial, esophageal, pericardial branches.
5. Abdominal aorta: Diaphragm (T12) → bifurcation (L4).
   • Visceral branches: celiac trunk, SMA, IMA, renal, gonadal, suprarenal.
   • Parietal: inferior phrenic, lumbar, median sacral.
   • Terminal: common iliac arteries → internal (pelvic) + external (lower limb).

Key Physiology

• Windkessel effect: aortic compliance dampens pulsatility → continuous capillary flow.
• Coronary perfusion occurs mainly in diastole (aortic root pressure).
• Baroreceptors in aortic arch/carotid sinus → BP regulation.

Clinical Correlates

• Coarctation (post-ductal) → upper body HTN, lower body hypoperfusion.
• Aortic dissection: tearing chest/back pain, pulse deficits.
• Coronary ostial stenosis → ischemia.