Introduction

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

Anatomy of and location of pulmonary valve 

The following figure represents the anatomical structure of the heart and displays the location of the pulmonary valve.³ The heart consists of four chambers: the right atrium, right ventricle, left atrium, and left ventricle. The pulmonary valve is located between the pulmonary artery and the right ventricle, separating those two parts. 

The pulmonary valves are made up of collagen fibres and elastin sheets. The following figure is a photograph of the anatomical structure of the pulmonary valve:⁴

Role of pulmonary valves

Circulation in the heart

The blood from the lungs, where the oxygen is filled within our blood, comes from the pulmonary vein into the left atrium. Then, blood fills into the left ventricle, which pumps oxygenated blood into the aorta, and is then delivered to the body cells. The blood delivered to the bodily cells becomes deoxygenated and is delivered into the right atrium, where it 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.

Heart conditions which require action

1. Pulmonary Atresia

Pulmonary atresia is a kind of birth defect that results in non-existence of the pulmonary valve. There are two versions of pulmonary atresia.⁵

2. 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. In  the case of pulmonary regurgitation, the pulmonary valve does not fully close.⁶ 

3. Pulmonic Stenosis

Pulmonic stenosis is a stiffness of the pulmonary valve that results in defects in blood circulation in the heart.⁷

Pulmonary valve repair

Pulmonary valve repair is the process of surgically repairing the original pulmonary valve of the heart. The main goal is to re-initiate the function of the pulmonary valve and prevent multiple operations required with the replacement method.⁸

There are three main techniques of the operations carried out for your pulmonary valve repair, and the decision is made depending on the condition specific to your pulmonary valve dysfunction.

1. Balloon Valvuloplasty

When you have pulmonic stenosis, this operation method is preferred to keep the pulmonary valve open when required. As shown in the figure below, a catheter with a balloon on the tip is inserted through the pulmonary valve.^9,10 The method is carried out by local anaesthetic injection, hence is known as a less invasive procedure. Then, the balloon is inflated by the surgical team, and subsequently, the valve leaflets are forced to open.

2. Commissurotomy 

This method of surgery is applied when the pulmonary valve leaflets are fused or thickened.¹¹ The aim of the surgery involves incision of the thickened or fused part of the valve leaflets to split them and recover their function.

3. Annuloplasty

This operation aims to re-maintain the ring shape of the pulmonary annulus consequently widening the right ventricular outflow tract (RVOT).¹¹ It is done by using patches or annuloplasty rings to maintain the actual shape of pulmonary leaflets to enhance the full closure of the valve. 

Pulmonary valve replacement

For the treatment of pulmonary artery defects, replacement surgery is another option of treatment apart from the pulmonary valve repair method. The types of replacement valves can be categorised into three main groups, and the decision is carried out by the healthcare providers due to the individual specificity of the heart condition. 

1. Mechanical Valves 

Mechanical valves are commonly used in situations where repetitive surgeries have been carried out and upcoming repetitions of the surgeries will have concerning consequences.⁸ The mechanical valves are constructed artificially using metal or carbon and replace the original pulmonary valve. This method is also considered when biological valves become non-durable and require re-operation.⁸ However, the mechanical valves require long-term use of blood thinning medication, and those medications have confirmed side effects with reduced quality of life.¹²

2. Biological Valves

The biological heart valves are also known as bioprosthetic valves.¹² Those biological valves are constructed from biological materials as an end-product of biology, biochemistry, and mechanical engineering branches. The biological valves do not require anticoagulants, known as blood thinners, for a long time.

3. Ross Procedure

When infants and children get the pulmonary valve replacement, the artificial valves do not grow as the patient grows. Therefore, the valve remains insufficient and re-operation is required for many years to change the size of the inserted valve. At this point, the Ross procedure is recommended where the donor is selected to transfer a real valve into the patient's body. This donor valve grows together with the child or the infant and is known as the pulmonary homograft.¹³ Compared to other techniques of pulmonary valve replacement, Ross's procedure confirmed to have almost no risk of embolism. Nevertheless, in 15-20 years another heart operation is required to tackle the regurgitation or stenosis acquired by the homograft valve.

How to diagnose pulmonary valve diseases

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. General diagnostic methods are:^5,7,16

• Echocardiogram
• Cardiac Magnetic Resonance Imaging
• Cardiac Computed Tomography 
• Cardiac Catheterization
• Pulmonary Angiography
• Chest X-ray
• Genetic Testing
• Blood Test for Hemogram and Blood Cell Count
• Pulse Oximetry for Blood Oxygen Level

Deciding the treatment

The choice of type of operation for the pulmonary valve depends on a variety of factor evaluation. 

Condition of the pulmonary valve

• Repair: Pulmonary valve repair may be considered when the valve structure is amenable to correction. This could include addressing issues such as leaflet abnormalities, commissural fusion, or limited stenosis.
• Replacement: If the valve is severely damaged, or calcified, or the leaflets are beyond repair, replacement may be necessary.

Valve function

• Repair: If the valve has minimal dysfunction and can be effectively restored to normal function through repair techniques.
• Replacement: If the valve is severely regurgitated (leaking) or stenotic (narrowed) repair may not be sufficient to restore proper function.

Underlying heart conditions

• Repair: Patients with certain congenital heart defects or specific valve abnormalities may benefit from repair if the anatomy allows.
• Replacement: In cases where the valve dysfunction is part of a more complex heart condition, replacement may be a more suitable option.

Patient age and health

• Repair: Repair is often preferred in younger patients as it may avoid the need for lifelong anticoagulation therapy associated with some prosthetic valves.
• Replacement: In older patients or those with other health considerations, replacement may be chosen based on durability and long-term outcomes.

Type and severity of valve dysfunction

• Repair: Typically considered for mild to moderate valve dysfunction, where the underlying anatomy allows for effective correction.
• Replacement: Considered for severe valve dysfunction or if repair is not feasible due to the extent of damage.

Risk factors

• Repair: This may be favoured if the patient is at lower risk for complications and the repair is expected to have a good outcome.
• Replacement: Considered when the risk of repair is deemed too high or if replacement provides a more predictable and successful outcome.

Patient preferences

• Repair: Some patients may prefer repair if it aligns with their preferences, especially if it allows for a more natural valve and avoids the use of mechanical prosthetics.
• Replacement: Others may opt for replacement if the longevity and predictability of outcomes are more critical to them.

Preparation for the pulmonary valve surgery

The patient is registered into the hospital the day before the surgery for detailed documentation of the conditions such as:¹⁰

Evaluation of the patient's condition (age, weight, height)

• Obtaining medical history 
• Knowledge of previously or currently used medications including anticoagulants
• Clinical evaluation of heart, vascular, liver, kidney, and musculoskeletal functions 
• Monitoring for the presence of any other symptoms
• Checking the presence of any allergies
• Evaluation of complications that arose after the previous surgeries 
• Any known history of complications of anaesthesia or familial history 
• Documentation of social and sexual activities
• Restriction of food and drink after midnight 
• Cleaning of the chest and making it sterile

Prognosis after the pulmonary valve surgery

The mortality rate and reduced life quality are high after the pulmonary valve repair operations. The mortality is highly low and life quality is much higher after the pulmonary valve replacement operations. Especially the lack of requirement for anticoagulants after the replacement surgery shows impressive results in good quality of life. However, strict monitoring is required to prevent any complications and enhance early detection of the demand for a re-operation.¹⁷

In conclusion, for the long-term benefit of patients who have been undergoing open heart surgeries, replacement surgery is the most beneficial.¹⁸

Conclusion

Pulmonary valve repair surgery involves all the procedures carried out on the body’s natural pulmonary valve to resolve its functional defects. On the other hand, pulmonary valve replacement involves all the procedures carried out after the removal and disposal of the body’s natural pulmonary valve to replace it with a functioning one with a variety of options. The choice of operation is made including a range of factors but the most important ones are the age, the severity of the damage in the pulmonary valve, and the number of heart surgeries that have been done previously. Lastly, very careful monitoring is required due to the development of post-surgical complications and the necessity of several operations.