HEART valve conditions are some of the commonest reasons why persons are referred to a cardiac surgeon. To help you understand these conditions, you will need to get through a few basics.

BASIC HEART FUNCTION

The heart is a muscular pump whose purpose is to pump blood to the lungs and the rest of the body. It is divided into two sides, right and left, with the right having the responsibility of accepting blood returning from the body and pumping it to the lungs to pick up oxygen. This oxygen-rich blood from the lungs then travels to the left side of the heart where it is pumped to the rest of the body. This coordinated one-way flow of blood through the heart is ensured by the heart valves, two being present on either side of the heart.

Each side of the heart has an upper chamber called an atrium, and a lower chamber called a ventricle. A valve separates these two chambers. The ventricle is the chamber responsible for squeezing blood out of the heart. On its way out of the heart to the lungs or rest of the body, blood will flow across another set of valves. These cardiac valves should offer a low resistance to blood flowing in the right direction and should be able to close completely if blood tries to flow backwards.

There are a variety of disease states that can affect these valves and cause them to not work the way they should. These conditions can lead either to the valves becoming very narrow or very leaky. Narrowing of a cardiac valve is called stenosis and in this situation, blood has a very difficult time passing through. This will lead to an insufficient amount of blood reaching either the lungs or the rest of the body, depending on which side of the heart is affected. A leaky cardiac valve is said to be incompetent or regurgitant and in this situation the back flow of blood within the heart can eventually have serious consequences on heart function.

Most adults referred for heart valve surgery tend to have conditions affecting the valves on the left side of the heart. The mitral valve is present between the left upper chamber (atrium) and the lower chamber (ventricle). The aortic valve is located between the left ventricle and the aorta, which is the major blood vessel leaving the left side of the heart to the rest of the body. Either of these valves can develop stenosis or regurgitation.

CAUSES

The list of causes of cardiac valve disease can be quite exhaustive so we will look at the common ones that we see in practice. In Jamaica, rheumatic fever is still relatively common in comparison to developed countries. This condition, over a long time, can affect the cardiac valves — a condition termed rheumatic heart disease.

In most cases, this leads to stenosis of either the mitral or aortic valve. As persons age, the aortic valve can also become narrower due to the deposition of calcium on the valve tissue. A leaking valve can develop from rheumatic heart disease as well, and at times, both stenosis and regurgitation can exist in the same valve.

However, valvular regurgitation can also result from valve infections, heart attacks and also a general lack of supporting tissue that make up the valve.

SYMPTOMS

The symptoms of heart valve disease can be similar for both stenosis and regurgitation. These include:

• Shortness of breath, especially with activity;

• Easy fatigability: People may realise that everyday tasks are becoming more and more difficult and they may have to stop and rest quite often.

• Cough, which may be associated with frothy sputum;

• Inability to lie flat: People may notice that they have to be sleeping on more than one pillow to be comfortable.

• Chest pain, especially on exertion;

• Passing out (syncope);

• Palpitations: An awareness of the heartbeat.

Some of these symptoms are also seen in other conditions so it is important to see your doctor if you are experiencing any of them.

SPECIAL TESTS

The distinction between stenosis and regurgitation can be made when the person is examined by their physician. However, there are specific tests that are done which give a lot more information. Key to the diagnosis of heart conditions is the echocardiogram. This is an ultrasound test of the heart, which uses sound waves to create an image of the heart. This test can give quite detailed anatomical and functional information and most times is enough to make a recommendation on surgery. Other tests may also include computerised tomography or magnetic resonance imaging scans.

With confirmed significant valve disease, some patients accepted for surgery may also be asked to have a coronary angiogram performed to look at the blood vessels supplying the heart muscle.

Based on all the factors, a recommendation for surgery may be made and at this time, the person will be referred to see a cardiac surgeon.

SURGICAL OPTIONS

A diseased cardiac valve can either be repaired or replaced. A decision on this will be taken by the surgeon after many factors are considered including, how badly the valve is damaged and how sick the patient is at the time of presentation.

In general, a repair is undertaken when feasible, especially when dealing with the mitral valve. However, if a good repair is not possible, the surgeon will choose to replace the valve.

When a valve replacement is necessary there are generally two valve types to choose from: a mechanical valve or a bioprosthetic valve. We usually involve the patient in this decision-making process and ultimately they will decide on which type would suit them.

A mechanical valve is constructed from all man-made material. It consists of a fabric ring into which two leaflets, made from a hard carbon material, are mounted. This is the valve type recommended in young persons.

Advantages include its durability as it is expected to last a lifetime without undergoing any form of structural deterioration. However, the main drawback of this valve type is the need for anticoagulants (blood thinners).

A bioprosthetic valve is made from natural tissue which, in most instances, comes from pigs, cows or humans. With this valve type, lifelong anticoagulation is not necessary. However, the body will react to this foreign tissue by mounting a response that, over time, can degrade the valve. Patients may therefore require another replacement. This response is pretty exaggerated in young persons, hence why tissue valves are usually not recommended for this age group. In people over the age of around 60 years, the body’s responses are much less potent and tissue valves can last for a very long time and may not need replacement, considering average life expectancy.

At surgery, there are a variety of ways to approach the procedure depending on which valve is affected. Standard surgery includes entering the chest in the middle and placing the patient on what is called cardiopulmonary bypass. This machine serves as the heart and the lungs during the procedure and is controlled by a specially trained person called a perfusionist.

After establishing the patient on this machine, valve repair or replacement can then proceed. After completing the procedure, the patient is gradually weaned off the bypass support while their own heart takes back over control of the circulation. Newer methods have been developed and, depending on what needs to be done, open surgery can be entirely replaced with more minimal options.

Heart valve disease remains a common condition and in Jamaica, rheumatic heart disease is a major contributor. Valve replacement remains a viable option and it is important that patients with symptoms seek medical attention early to avoid the development of long-term and possible detrimental complications.

With early intervention, most patients can expect to lead normal lives after recovering from surgery.

Dr Sunil Stephenson is a consultant cardiothoracic surgeon at the University Hospital of the West Indies. He is also a lecturer in the Faculty of Medical Sciences at the University of the West Indies, Mona. Please send questions and comments to sunilstephenson@hotmail.com. He may be contacted through the office numbers 977-6883 or 927-1270.