Valvular heart disease - What is it? (Part 1 - Mitral Stenosis)

So to better understand what is a valve doing in our heart, let's look at definition and general anatomy of a heart :
According to wikipedia.com :

A heart valve normally allows blood to flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart. A heart valve opens or closes incumbent on differential blood pressure on each side.

The four main valves in the heart are:

• The two atrioventricular (AV) valves, the mitral valve (bicuspid valve), and the tricuspid valve, which are between the upper chambers (atria) and the lower chambers (ventricles).
• The two semilunar (SL) valves, the aortic valve and the pulmonary valve, which are in the arteries leaving the heart.

IMG SRC : https://www.thoughtco.com/heart-anatomy-373485

What can go wrong with those valves?

Valves as you can guess from the word, is a mechanical tool that god created in all of human beings to function as a guardian of the dynamic of blood. In this context, to prevent the back flow of blood. So that it will always reach from one chamber to another always.

In Valvular heart disease, this valve lost its function. It may results in inability to prevent back flow (which is termed REGURGITATION/INSUFFICIENCY) or the valve itself become hardened in some way thus making the orifice too small for blood to flow (which is termed STENOSIS)

MITRAL STENOSIS

Mitral here refer to mitral valve, which is situated on the left side of the heart. Left side of heart usually handles a bigger pressure compare to right side of heart. That's why valves on the left side for example aortic and mitral are usually the most encountered defect. The most common cause for mitral stenosis is rheumatic heart disease which is caused by the notorious bacteria call B-hemolytic streptococcus. After years, the condition worsened by calcification of mitral valve, cusp fusion and eventually severely narrowed orifice of mitral valve.

Pathophysiology

As you can see, left atrium receives blood from lungs via pulmonary veins. When there is more pooling of blood in atrium, it will directly affect the pressure in pulmonary vein -> pulmonary artery -> right side of heart. When atrium have to work hard to pump through the incompetent valve, atrium will become larger in size. And thus, the beating rhythm of atrium is disrupted, which cause atrial fibrillation. And atrial fibrillation further causes pulmonary edema.

What can you hear on auscultation?

If you ever tried to find out the sound of the heart, it will only produce two kind of sound. It's lub and dub. Lub is presented here as S1 and dub presented here as S2. S1 is caused by turbulence due to closure of mitral and tricuspid valve. S2 is caused by closure of pulmonary and aortic valve.

Since the patient is having problem with mitral valve. You can expect to hear some abnormalities with S1. So as the valve suddenly opens with increased force from atrium, an "opening snap" can be heard. Imagine blowing hard through a drinking straw with one finger covered the open end of straw, and suddenly release it. You will hear a quick sharp sound followed by rumbling sound as the turbulence progressively slow. The same happens in heart.

All of this occurs in the period when there's blood filling in the ventricles of heart which is called DIASTOLIC STAGE Coincidentally, it appears to be after S2 ( which is closing of mitral / tricuspid valve).

In a nutshell, you should hear MID DIASTOLIC MURMUR with opening snap just after S2

Diagnosis

• Chest X-ray

  1. Left atrial enlargement - double shadow in right cardiac silhouette)
  2. Calcified mitral valve
  3. Pulmonary oedema (Pulmonary valve congestion and pulmonary arteries enlargement)

• ECG (Electrocardiogram)

  1. P-mitrale on sinus rhythm, Right Ventricular Hypertrophy

• Echocardiography is diagnostic

  1. valve orifice < 1cm2/ m2 body surface area
     

Management

• Valvotomy
  (Surgical procedure to manually open the valve by means of balloon catheter, dilator)

• Valve replacement
  (Work successfully for >20 years but need to take anticoagulant drug for lifelong)
  

Additional video explanation, credit to medcram :

Congratulations if you made it to the end of this article! I know this article is too technical for average person, but I'm sure you'll learn something from it. For me, it's a revision and there's a saying goes you'll learn more when you teach others. And I find this saying to be really true. I hope you enjoyed it. Do give me feedback if I should make such post again.