• The literal meaning of stenosis is “narrowing”, and mitral stenosis is the narrowing of the mitral valve. This narrowing causes less blood to flow from the heart to the rest of the body. As a result, the upper heart chamber swells as pressure builds up which can lead to blood and fluid collection in the lung tissue (pulmonary edema). This is what causes the common symptom of shortness of breath [1].
  • The most common cause of MS is rheumatic fever, which is a condition that occurs when strep throat or scarlet fever is not properly treated, but it can also be congenital. It is much less common in developed countries than it is in underdeveloped countries; nevertheless, MS can lead to serious heart complications if left untreated, and can have risks for the mother during pregnancy [2].


  • Cough, possibly with bloody phlegm
  • Difficulty breathing during or after exercise (this is the most common symptom)
  • Trouble breathing while lying flat
  • Fatigue
  • Frequent respiratory infections
  • Palpitations
  • Swelling of feet or ankles
  • A murmur from mitral stenosis can be heard with a stethoscope. It typically sounds like a rumbling sound during the resting phase of the heartbeat, and usually gets louder just before the heart contracts. An irregular heartbeat and lung congestion may also be heard.

Possible Complications may include[1]:

  • Atrial fibrillation and atrial flutter
  • Blood clots
  • Congestive heart failure
  • Pulmonary edema
  • Pulmonary hypertension

Hemodynamic deterioration (poor circulation) usually occurs during the third trimester in women who have moderate-to-severe mitral stenosis. During labor and delivery, the increase in blood volume and heart rate also elevates left atrial pressure, which leads to pulmonary edema. This can cause labor to become hazardous, even more so when contractions cause additional displacement of blood volume.

Atrial fibrillation in a pregnant patient with mitral stenosis can lead to rapid decompensation. Many times, medications such as beta blockers are used to reduce heart rate and diuretics are used to reduce blood volume and pressure in the left atrium. Anticoagulants are typically also used since atrial fibrillation increases risk of stroke.


  • In mild cases, no treatment may be necessary. In serious cases however, a percutaneous mitral valvuloplasty may be performed. This procedure is when a catheter is inserted into a vein (usually in the leg), and is threaded up to the heart. There, a balloon at the tip of the catheter is inflated to widen the mitral valve and improve blood flow. Surgery may also need to be performed to repair or replace the mitral valve [1].
  • Women that have severe MS are advised to limit physical activity during pregnancy. This typically results in bed rest for the mother during the third trimester. Medications typically used are diuretics, beta-blockers, and anticoagulants [3].
  1. Mitral stenosis. NIH Web site. https://medlineplus.gov/ency/article/000175.htm. Accessed June, 2017.
  2. Kannan M, Vijayanand G. Mitral stenosis and pregnancy: current concepts in anaesthetic practices. Indian J Anaesth. 2010; 54(5): 439–444. doi: 10.4103/0019-5049.71043.
  3. Norrad RS, Salehian O. Management of severe mitral stenosis during pregnancy. Circulation. 2011; 124: 2756-2760. https://doi.org/10.1161/CIRCULATIONAHA.111.030601.

By: Stephanie Kramer