Pulmonary Arterial Hypertension

Clinic

• PH or PHTN is a condition of increased blood pressure in the arteries of the lungs.

• Signs / Symptoms
  • Shortness of breath / Cyanosis
  • Fatigue
  • Chest pain
  • Palpitations
  • Right-sided abdominal pain
  • Poor appetite
  • Lightheadedness / Fainting
  • Swelling (legs/ankles)

Causes

• Primary PH (resulting from a disease of the pulmonary arteries)
• Secondary PH (resulting secondary to other, non-vascular causes).

Pathogenesis

• The pathogenesis of pulmonary arterial hypertension (WHO Group I) involves the narrowing of blood vessels connected to and within the lungs.
• This makes it harder for the heart to pump blood through the lungs, as it is much harder to make water flow through a narrow pipe as opposed to a wide one.
• Over time, the affected blood vessels become stiffer and thicker, in a process known as fibrosis.
• The mechanisms involved in this narrowing process include vasoconstriction, thrombosis, and vascular remodeling (excessive cellular proliferation, fibrosis, and reduced apoptosis/programmed cell death in the vessel walls, caused by inflammation, disordered metabolism and dysregulation of certain growth factors).
• This further increases the blood pressure within the lungs and impairs their blood flow.

Molecular pathology

• The molecular mechanism is not known yet, but it is believed that the endothelial dysfunction results in a decrease in the synthesis of endothelium-derived vasodilators such as nitric oxide and prostacyclin.
• Moreover, there is a stimulation of the synthesis of vasoconstrictors such as thromboxane and vascular endothelial growth factor (VEGF).
• These result in a severe vasoconstriction and vascular smooth muscle and adventitial hypertrophy characteristic of patients with PAH.

Mias ms

HHV-8