Definition and Overview

Pulmonary stenosis is the narrowing of the pulmonary valve or artery resulting in limited blood flow from the heart to the lungs. The condition forces the heart muscle to work harder to pump more blood. Over time, this can lead to the thickening of the heart muscle, which increases the patient’s risk of heart failure.

Pulmonary stenosis usually develops before birth (congenital) but it can also be a complication of another illness like rheumatic fever and carcinoid syndrome. It can be treated by widening the narrowed valve or artery through a catheter-based procedure or the surgical repair or replacement of the damaged valve using either tissue (bioprosthetic) or mechanical valve.

Causes of Condition

Pulmonary valve stenosis can be a congenital defect that occurs when the valve fails to develop properly during pregnancy. It is often observed in children who also have other congenital heart abnormalities and rare genetic conditions, particularly Noonan and Williams syndromes.

In adults, it may develop due to other medical conditions that tend to increase the risk of heart valve injuries. These include:

  • Carcinoid syndrome - Occurs when a carcinoid tumour secretes certain chemicals into the bloodstream, causing the heart valve to thicken and eventually leak. About 40% of patients with this condition develop carcinoid heart disease associated with heart valve dysfunction.

  • Rheumatic fever - Causes rheumatic heart disease that commonly affects the heart’s chambers. It can result in valve stenosis and regurgitation as well as damage to the heart muscle.

Key Symptoms

Patients with mild to moderate pulmonary stenosis are usually asymptomatic. However, in severe cases where a significant amount of blood is unable to get through the pulmonary valve or artery, the baby’s tongue and lips may appear bluish (cyanotic), which indicates that not enough oxygen gets to his or her lungs. This is a medical emergency that requires immediate surgical correction.

Adult patients, on the other hand, commonly experience chest pain, fatigue, breathlessness, or even fainting.

If not managed properly, pulmonary stenosis can lead to a number of life-threatening complications, including heart enlargement (which can permanently weaken the heart), infection, heart failure, and even death.

Who to See and Types of Treatments Available

Pulmonary stenosis is often suspected when a heart murmur is detected during a baby’s routine check-up. A heart murmur, which is a common symptom of a congenital heart disease, refers to an unusual swishing or whooshing sound that can be heard through a stethoscope during a physical examination. To determine what causes it, the following tests are often carried out:

  • Chest x-ray

  • Echocardiogram

  • Electrocardiogram (ECG)

  • Magnetic resonance imaging (MRI)

  • Cardiac catheterisation

The results of the above tests help doctors determine if the symptoms are caused by the narrowing of the pulmonary valve/artery. The same tests are used to assess the severity of the condition. For mild to moderate cases, doctors usually advice watchful waiting or active surveillance where patients are monitored and required to undergo periodic tests and exams to ensure that their condition is not worsening and causing complications. This is often prescribed when the risks of treatments are greater than their possible benefits.

Severe cases, on the other hand, are commonly corrected with surgical procedures, such as:

  • Balloon valvuloplasty - A minimally invasive procedure that aims to open or widen the narrowed pulmonary valve or artery. It is often the treatment of choice for infants and young children because it is less risky. For this procedure, the surgeon will insert a thin catheter into a vein in the leg and then thread it to the heart using imaging guidance. When the catheter reaches the narrowed valve, a small balloon at the end of the catheter is inflated and deflated until the opening of the valve widens and normal blood flow is restored. Although the procedure is minimally invasive, patients may be required to stay at least one night in the hospital for close monitoring. Balloon valvuloplasty is highly effective especially when performed in younger patients but it does not provide a guarantee that the valve won’t narrow again in the future. If this happens, the patient will undergo another surgery to replace the valve or artery.

  • Open-heart surgery - If the patient has other heart problems that require surgical correction or is considered not a good candidate for balloon valvuloplasty, open-heart surgery is performed. The procedure requires cutting the chest open, which gives the surgeon access to the heart muscles, arteries, and valves. It is performed under general anaesthesia and depending on the number of congenital heart defects that need to be corrected, it can last for several hours.

If the valve or artery is damaged beyond repair, it is replaced with a mechanical valve made from synthetic materials or biological valve made from pig or cow valves. Both options have pros and cons, which the surgeon will discuss at length with the patient or the patient’s parents or guardians before the procedure. Manufactured valves are made from strong durable materials and can last for several years. However, patients must commit to taking blood-thinning medications for the rest of their lives to prevent the formation of blood clots. Tissue or bioprosthetic valves, on the other hand, do not require long-term use of blood-thinning medications but they typically need to be replaced later in life as they can also deteriorate.

When compared to balloon valvuloplasty, open-heart surgery is far riskier as it can result in a number of serious complications, including the following:

  • Blood clots

  • Bleeding

  • Arrhythmias

  • Heart attack

  • Stroke

  • Infection

References:

  • Options for heart valve replacement. American Heart Association. http://www.heart.org/HEARTORG/Conditions/More/HeartValveProblemsandDisease/Options-for-Heart-Valve-Replacement_UCM_450816_Article.jsp#.WBjmPmXT8lZ.

  • Pulmonary valve stenosis http://www.heart.org/HEARTORG/Conditions/CongenitalHeartDefects/AboutCongenitalHeartDefects/Pulmonary-Valve-Stenosis_UCM_307034_Article.jsp

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