Black Pean information #8 (calm down TBS)

[tronella]

I think this was posted during/after the broadcast of episode 2. I don't think there are any spoilers past episode 1, but whether you read it is up to you, of course!

What is a SNIPE?

I expect a lot of people are wondering what kind of thing the “SNIPE” brought in by Takashina is and whether it really exists. The SNIPE is used in the drama as a “mitral valve treatment”. In this entry, Dr Yamagishi will give his explanation, starting with a discussion “about mitral valve treatment”, followed by “the differences between the Saeki method and the SNIPE” and “does the SNIPE really exist?”

About mitral valve treatment

The heart has four chambers, with gates (valves) between each chamber. This is to make sure that the blood flows in a single direction. The upper left chamber is the left atrium and the chamber below that is the left ventricle. The left atrium and left ventricle are separated by a valve called the mitral valve, and the left ventricle and the aorta are separated by the aortic valve. Blood that has taken in oxygen from the lungs enters the left atrium, passes from the left atrium through the mitral valve into the left ventricle, then passes through the aortic valve into the aorta and flows into the rest of the body.

Broadly speaking, there are two kinds of mitral valve disease. One is called mitral stenosis, a disease where the mitral valve doesn’t open properly and becomes narrower, restricting the blood flow from the left atrium to the left ventricle. The other is mitral valve insufficiency, a disease where the valve doesn’t close, so the blood doesn’t flow from the left ventricle into the aorta, but flows back into the left atrium instead.

There are two types of treatment (mitral surgery): mitral valve repair and mitral valve replacement.

Please think of repair surgery like mending a gate. It’s just like installing the gate’s frame securely, replacing the hinges and so on.

Replacement surgery is an operation where the valve is replaced with a completely new prosthetic valve.

You can think of it this way: if the damage to the valve is mild, it is repaired, and if it is severe, it is replaced.

Usually, the chest is cut open in the middle (midline incision, midline thoracotomy), a heart-lung machine is used and the heart is stopped to perform the surgery. These days, it is possible to make a small incision in the right chest for the operation (it is only possible in patients who meet specific criteria).

The differences between the Saeki method and the SNIPE

In Black Pean, two types of mitral surgery called “the Saeki method” and “the SNIPE” appear.

The Saeki method...?

The Saeki method is an operation (repair surgery) where a midline incision (thoracotomy) is performed, a heart-lung machine is used and the valve is repaired while the heart is still moving.

The SNIPE...?

Properly speaking, the SNIPE is a mitral valve replacement technique using a transapical (catheter) approach. You can think of “trans~” as meaning “going through the ~” here. So a transapical approach means inserting a catheter (a medical tube) through the apex, which is the tip of the heart’s left ventricle, to replace the mitral valve.

As Dr Takashina says, this does not require a heart-lung machine, and only a 4-cm incision is made in the left chest. There is a microsensor inside its tip, so it can reach the mitral valve exactly on target and replace it with a new one. X-ray imaging shows the new valve coming out of the SNIPE, but the new valve is inside that stent shaped like a jungle gym. After removing the device from the apex, a haemostatic device can be placed at the end to prevent bleeding (in some cases, sutures may be required).

Does the SNIPE really exist?

I mentioned the aortic valve above, and aortic valve replacement by catheter (a narrow tube-like object inserted into a blood vessel) is a treatment that can already be carried out (it is used in Japan too, and is possible in patients who meet specific criteria). It can be performed through the apex, or through an artery in the top of the leg called the femoral artery (of course, it can only be performed in patients who meet specific criteria).

The SNIPE (or a similar medical device) is not yet being used in Japan, and globally is still in the clinical testing phase. But the SNIPE (or a similar medical device) is being developed by dozens of medical device manufacturers throughout the world in a fierce competition, and it may be used in Japanese patients some day. Beyond that, in future there may come a time when it is possible to replace or perfectly repair a mitral valve through the femoral vein, a vein in the top of the leg. This is how mitral valve treatment is currently progressing worldwide.