Stenosis

Stenosis (from the Greek στένωσις — narrowing, compression) is a pathological, persistent narrowing of the lumen of any hollow anatomical formation (blood vessel, heart valve, digestive tract, respiratory tract, or spinal canal).

This narrowing prevents the normal passage of physiologic media (blood, air, food, cerebrospinal fluid) through it, which leads to impaired function of the corresponding organ or system. Clinical manifestations, severity, and prognosis of stenosis depend entirely on its localization, degree of narrowing and speed of development.

Aetiology and Pathophysiology

The narrowing can be caused either by pathologic changes in the wall of the structure itself or by its compression from the outside.

The primary causes of the development of stenosis:

• Degenerative processes: most common cause in adults.
  • Atherosclerosis: formation of cholesterol plaques in the walls of arteries (stenosis of coronary, carotid arteries).
  • Calcification: deposition of calcium salts in the flaps of the heart valves (aortic stenosis).
  • Osteoarthritis: bony growths (osteophytes) can cause stenosis of the spinal canal.
• Congenital abnormalities: malformations present from birth (congenital aortic stenosis, pylorostenosis in infants).
• Inflammatory and scarring changes: formation of scar tissue after injury, burns, inflammation, or surgery (scarred esophageal stenosis after reflux esophagitis, tracheal stenosis after prolonged intubation).
• Tumor: growth of a neoplasm that either blocks the lumen from the inside or compresses it from the outside.

Pathophysiologically, stenosis leads to two main consequences: increased stress on the chambers upstream of the narrowing site (e.g., myocardial hypertrophy in aortic stenosis) and inadequate blood supply or function of the sections downstream of the narrowing (ischemia, hypoxia).

Clinical relevance and examples

Stenosis is the basis of many widespread and clinically significant diseases.

The most common and important locations are:

• Cardiovascular system:
  • Stenosis of the heart valves: most commonly the aortic and mitral valves. Leads to shortness of breath, heart pain, and the development of heart failure.
  • Coronary artery stenosis: underlies coronary heart disease, causes angina and myocardial infarction.
  • Carotid artery stenosis: is the leading cause of ischemic strokes.
• Central nervous system:
  • Spinal canal stenosis: compression of the spinal cord or nerve roots, manifested by pain, numbness, and weakness in the extremities.
• Respiratory system:
  • Laryngeal and tracheal stenosis: a life-threatening condition that causes noisy breathing (stridor) and choking.
• Digestive system:
  • Esophageal stenosis: leads to difficulty swallowing (dysphagia).
  • Pylorostenosis (stenosis of the pylorus): in newborns, it is manifested by uncontrollable vomiting like a “fountain”.

Diagnosis and treatment

Stenosis is diagnosed using medical imaging techniques. For the vessels and valves of the heart, ultrasound with Doppler ultrasound (cardiac US, echoCG) is widely used. CT and MRI scans are used to evaluate the spinal canal, brain, and internal organs. “The gold standard” for the diagnosis of arterial stenosis is angiography.

Treatment is aimed at eliminating the narrowing. Depending on the cause and degree of stenosis, it can be conservative (drug therapy), minimally invasive (balloon angioplasty and arterial stenting) or surgical (heart valve replacement, bypass surgery, decompressive spinal surgery).