What Is The Pulmonary Valve?

Overview

The pulmonary valve is located within the heart and regulates the blood flow out of the heart chambers. Its role is highly crucial and any malformation results in severe risk to health and can be lethal if remains untreated. Being aware of the disorders associated with the pulmonary valve is a way of safeguarding the general health of the pulmonary valve. The conditions linked to pulmonary valve health are predominantly pediatric. This article will introduce you to the topic and help you be aware of the possible signs.

The pulmonary valve separates the right ventricle of the heart from the pulmonary artery.¹ The role of the pulmonary valve is highly crucial in the circulatory system for the prevention of flowing blood in the wrong direction. The malfunctioning pulmonary valve results in severe diseases leading to death.²

The heart is made of four chambers; right atrium, right ventricle and left atrium, left ventricle. The pulmonary valve is located between the pulmonary artery and the right ventricle whereas it separates those two parts. The building materials of pulmonary valves are collagen fibres and elastin sheets.^3,4

Role of pulmonary valve

The oxygenated blood from the lungs comes from the pulmonary vein into the left atrium and then into the left ventricle. The left ventricle pumps oxygenated blood into the aorta, then, it is delivered to the body cells. The blood delivered to the bodily cells becomes deoxygenated due to various processes.

This blood is delivered into the right atrium and fills into the right ventricle. Later on, the right ventricle pumps the deoxygenated blood to the lungs via the pulmonary artery passing through the pulmonary valve. The pulmonary valve prevents the backflow of the blood into the right ventricle.

Pulmonary valve disorders 

In the presence of defects in the pulmonary valve, various types of disorders can arise. 

Pulmonary atresia

This is a kind of birth defect resulting in the pulmonary valve's non-existence. There are two versions of pulmonary atresia. The first one is with a ventricular septal defect, where the pulmonary artery is underdeveloped and remains small together with a non-existing pulmonary valve and the second one is pulmonary atresia with an intact ventricular septum meaning, the pulmonary artery is much smaller, the pulmonary valve is absent, and the wall between the right and left ventricle is complete and intact, which means there is no connection between the ventricles.^6,7

Although the causes of pulmonary atresia with an intact ventricular septum are still unknown, it is however assumed to occur as a result of disturbances to the normal development processes of the embryo and genetic factors.⁷ 

The symptoms of pulmonary atresia with ventricular septal defect include:⁵ 

• Symptoms of central cyanosis, abnormalities in the colouring of the face into a bluish appearance as well as around the mouth and lips depending on the severity of the case. The respiration rate is higher and there is a feeling of breath shortness. Evidence of fatigue such as weakness in crying in babies, diminished tone, and weak clasping onto the breast
• Difficulty feeding

The symptoms of pulmonary atresia with intact ventricular septum:⁷

• Oxygen desaturation in the blood
• Cyanosis

Treatment options for pulmonary atresia are highly varied depending on the individual anatomic structures of the defective tissues of ventricles, the severity of the condition, and the size of the other heart valves. Also, in the case of pulmonary atresia with an intact ventricular septum, there is a possibility of performing several procedures to save the patient which means the requirement of many forms of surgery and treatments.^5,7

Pulmonary regurgitation

When the blood is pumped from the right ventricle into the pulmonary artery, the pulmonary valve fully closes to prevent re-flow into the right ventricle. Nevertheless, in the case of pulmonary regurgitation, the pulmonary valve does not fully close.⁸ The source of this enclosure can be any pathological condition related to either the structure or functioning of the pulmonary valve.

The most common causes of regurgitation are surgical valvotomy and balloon valvuloplasty which are carried out to treat another pulmonary valve condition known as stenosis.⁸ The other reasons that are less prevalent can be listed as the following:

• Pulmonary arterial hypertension 
• Carcinoid disease 
• Infective endocarditis 
• Rheumatic heart disease

High frequency of patients with pulmonary regurgitation are asymptomatic. In some patients, exertional dyspnoea, which is the difficulty in breathing during physical activity, may be observed with a decline in physical ability. When the condition is severe, other symptoms such as pedal oedema, congestive hepatomegaly (liver enlargement), and jugular venous distention (JVD) (swelling of the veins on the neck) start to arise.

Before treating the pulmonary regurgitation, at least two of the following criteria should be met. Accordingly, asymptomatic patients are not recommended to be treated. 

• Mild or moderate right ventricular systolic dysfunction (not being able to pump the blood properly) 
• Severe right ventricle dilation (this is a relaxation state of the right ventricle when it is not pumping any blood, during this stage blood fills inside the ventricle)
• Increased right ventricular systolic pressure (RVSP) (when the right ventricle contracts with high pressure while pumping the blood)
• Systematically decreasing capability of doing exercise

If at least two of the listed conditions above are present then the replacement surgery for the valve is carried out as a treatment option. However, if the underlying reason has nothing to do with previous surgery and the cause of the regurgitation is correlated with pulmonary arterial hypertension or carcinoid disease then medical therapy is recommended. For the poor surgical candidates, medical therapy such as diuretics, ACE inhibitors, and beta-blockers can be used as well.

Pulmonic stenosis

Pulmonic stenosis is a stiffness of the pulmonary valve that results in defects in blood circulation in the heart.⁹ It is a common situation in pediatric patients. The condition is not life-threatening and not a concerning situation, as long as there is an absence of complications and new onset of symptoms and is treated on time. In the cases of adult patients, other severe heart conditions are accompanied by pulmonic stenosis.

The roots of the pulmonic stenosis are linked to other underlying congenital structural cardiac syndromes like Fallot and Noonan syndrome.⁹ Additionally, maternal rubella syndrome, rheumatic heart disease, previously conducted cardiothoracic surgeries, and the presence of cardiac tumours can also yield pulmonic stenosis formation.

The patients most of the time remain asymptomatic until complications arise. On the contrary, in symptomatic patients, dyspnea or fatigue is monitored. Atypically, patients can experience angina or sudden cardiac arrest as well.

Only the severe stage patients are recommended to be treated by surgery such as pulmonary artery balloon angioplasty or stent placement. 

How to diagnose pulmonary valve disorders?

The type of diagnostic method is variable according to the type of pulmonary valve condition and co-existence of other congenital heart conditions as well as individual-specific disease conditions. The general list of diagnostic methods is as follows:^5,10

• Echocardiogram
• Cardiac magnetic resonance imaging
• Cardiac computed tomography
• Cardiac catheterisation
• Pulmonary angiography
• Chest X-ray
• Genetic testing
• Blood Test for haemogram and blood cell count
• Pulse oximetry for blood oxygen level

Prevention and maintenance of pulmonary valve health

Usually, pulmonary valve disorders are congenital, which means they are present at birth or arise during developmental stages before birth. Therefore, those cases cannot be prevented but the risk of acquired versions of it can still be prevented.¹¹

Enhancing the diet which contains high amounts of fruits, vegetables, whole grains, lean proteins, and unsaturated fats will help you to gain a healthier cardiovascular system. Avoiding saturated and trans fats, salty food, and additional sugars has been proven to lessen the risk of developing pulmonary valve disease. You can lower blood pressure by exercising regularly. 

Diabetic people especially have a higher chance of experiencing heart disease as well as pulmonary valve conditions. Smoking and over-consumption of alcohol are two enemies of the heart. Consequently, smoke-free life with a moderate level of alcohol consumption has a significant impact on your pulmonary valve health.

Furthermore, streptococcal infections lead to rheumatic fever which harms the pulmonary valve and results in pulmonary valve-related disorders. The vaccination programs for those infections are the best method of protection from developing heart conditions.

Summary 

The pulmonary valve is a very crucial part of the circulatory system and defects in the pulmonary valve can be lethal depending on the severity and being left untreated. Therefore, it is highly life-threatening to be aware of the conditions associated with pulmonary valve and take regular check-ups. Especially, the signs of problems in pulmonary valves should be monitored strictly, especially during babyhood and childhood since it is more prevalent in adolescence. 

In line with these, medical help is required to be accessed urgently. Finally, maintaining a healthy lifestyle and avoiding the risk factors can prevent you from the condition. For the cases where the condition is present with birth, acquired conditions can still be prevented to reduce the severity of the condition.