Endothelial Cells and Vascular Function Quiz

Endothelial Cells and Vascular Function

• Endothelial cells line blood vessels, forming a single cell layer.
• These cells are mechanosensitive, reacting to blood flow and pressure.
• They actively regulate vascular tone (dilation and constriction).
• They are key regulators of vascular homeostasis, responding to various physical and chemical signals.

Pulse Wave Velocity (PWV)

• PWV measures arterial stiffness via ultrasound.
• It assesses the speed of pressure waves traveling through arteries.
• Calculated by dividing distance by pressure wave transit time.

Atherosclerosis

• Atherosclerosis involves lipoprotein buildup in artery walls, forming plaques.
• This process involves endothelial activation, inflammation, necrosis, fibrosis, and calcification.
• Plaque formation narrows vessels, increasing risk of thrombi and rupture.
• Obstructs blood flow to vital organs (heart, brain, extremities).
• Carotid artery plaque scans (ultrasound) use color-coded flow for visualization (red=normal, yellow=high, blue=very high).

Endothelial Response to Shear Stress

• Endothelial cells respond to shear stress (blood flow friction).
• Shear stress influences endothelial health, preventing or promoting cardiovascular disease (CVD).
• Response changes depending on blood flow type (laminar, disturbed).

Vascular Calcification

• Calcium deposits are common in arterial walls for individuals aged 60+.
• Calcification can occur within the intima or media layer.
• Increasingly recognized as a serious problem.
• Leads to vessel stiffness and increased blood pressure.

Consequences of Atherosclerosis: Coronary Artery Disease

• Ischemic Heart Disease (Angina):
  • Coronary artery blockage or spasm reduces myocardial oxygen supply.
  • Symptoms: triggered by exercise, stress, cold.
  • Treatment: nitrates, calcium channel blockers, beta-blockers.
• Acute Myocardial Infarction (Heart Attack):
  • Blocked coronary artery by an embolus leads to myocardial ischemia.
  • Severity varies based on blockage size.
  • Symptoms: chest pain, shortness of breath, weakness, anxiety.
  • Diagnosis aid: elevated serum troponin (cardiac muscle damage).
• In-Stent Restenosis:
  • Re-narrowing of an artery after stent placement.
  • Caused by neointimal hyperplasia (new tissue growth).
  • Treatment: drug-eluting stents (reduce proliferation).
• Coronary Artery Bypass Graft (CABG):
  • Surgical procedure for patients with advanced atherosclerosis.
  • Bypasses blocked coronary arteries using grafts (saphenous vein, internal mammary artery).

Consequences of Atherosclerosis: Stroke

• Ischemic Stroke: Compromised brain blood supply.
  • Caused by local thrombus or distant plaque rupture (often internal carotid artery).
  • Variable symptoms based on affected brain region.
  • Treatment: tissue plasminogen activator (tPA), anticoagulants, carotid endarterectomy.
• Carotid Artery Imaging:
  • Ultrasound assesses carotid artery condition, including stenosis (narrowing).
  • Severe stenosis (>70%) may necessitate carotid endarterectomy surgery.

Consequences of Atherosclerosis: Peripheral Vascular Disease (PVD)

• Atherosclerosis obstructs large arteries outside coronary & aortic arch vasculature.
• Primarily affects lower extremities, causing ischemia.
• Symptoms: intermittent claudication (leg pain), color changes, wounds that don't heal.
• Severe cases involve limb loss.
• Increased mortality after foot ulcer development in PVD patients.

Consequences of Atherosclerosis: Aortic Aneurysms

• Pro-atherogenic factors (high blood pressure, cholesterol, smoking, inflammation) contribute to aortic stiffening.
• Weakening and bulging of aortic wall.
• Often asymptomatic, but may present as a pulsating abdominal mass.
• Aortic aneurysm rupture is life-threatening.
• UK screening for men over 65 via ultrasound.
• At-risk patients may receive surgical grafting.