Black Pean - Darwin information #5

[tronella]

Example of a disease that can be effectively treated by robot-assisted heart surgery

So far in Black Pean we’ve seen heart diseases like “aortic dissection”, “mitral incompetence”, “myxoma”, etc. but when I actually do robot-assisted surgery, I treat quite a lot of cases of atrial septal defects (ASD). This time, I’ll introduce that disease as an example.

◆ What is an atrial septal defect?

The wall between the heart’s right and left atria is called the “atrial septum”, and people with this disease are born with a hole (defect) in that wall. This accounts for about 6-10% cases of hereditary heart disease. It is twice as common in women as in men. Also, this hereditary disease is often discovered in adulthood, with many cases being identified in the patient’s 30s or 40s. In fact, it’s the most common hereditary heart disease found in adult patients. About 3% of the population have this disease, and about 10% of those have surgery. In other words, about 3 in every 1000 people have this surgery, and about 500 adults and 500 children have it per year.

The mechanism of ASD

In normal circulation, oxygenated (atrial) blood flows from the left atrium into the left ventricle, then is sent to the rest of the body. With ASD, some of the atrial blood goes through the hole (defect) from the left atrium into the right atrium, then goes back to the lungs again through the pulmonary circulation. In other words, there is more burden on the right atrium and right ventricle, and flow to the lungs increases in particular, which can cause pulmonary congestion or pulmonary hypertension.

Why does this disease develop?

Foetuses have this hole during their development to allow blood to flow from the left atrium into the right atrium. Foetuses don’t use their lungs, so blood returning from the rest of the body is cleaned by the mother’s body, and clean blood returning from the mother’s body is sent through her lungs as part of a single system. Usually, after the baby is born and starts breathing, this system stops working and the baby starts breathing with their lungs, at which point the hole in the septum usually completely closes up within a few days. This disease happens when it does not close completely but remains open.

Main symptoms of ASD

◇ Adult cases

Most people have no subjective symptoms until puberty, but from age 30 they develop arrhythmias and symptoms of heart failure like rising blood pressure in their pulmonary blood vessels and difficulty breathing. Complications can include atrial fibrillation, heart failure and pulmonary hypertension. In severe cases of pulmonary hypertension, surgery cannot be performed. In untreated cases, 50% of patients can live into their 40s or 50s.

It is also common for intravenous clots to flow into the heart or lungs and be disposed of there, but in unlucky cases where they flow from the right atrium into the left atrium, they can be carried into the brain and cause a stroke or cerebral abscess (paradoxical brain embolism).

◇ Newborn or infant cases

In cases where there is a lot of blood flow from the left atrium into the right atrium, newborns and infants can also have difficulty breathing, catch colds easily, gain weight easily, be unable to keep exercising for long periods and have other symptoms that require surgery.

Diagnosis and common treatment of ASD

If ASD is diagnosed by auscultation, chest X-ray or echocardiography, more detailed tests are performed and the patient’s suitability for surgery is considered. There are two types of treatment: catheter treatment or surgery.

Catheter treatment (Amplatzer method)

A catheter is used to close up the heart defect by placing a plug (Amplatzer septal occluder) to block the hole. An Amplatzer is a mesh-like occluder made from thin wires of a shape memory alloy that closes off the hole from both sides.

However, after catheter treatment the patient has to take anticoagulants, and there are also cases where catheter treatment is inappropriate due to the position or because of a metal allergy, so it cannot be used. There is also the risk that the occluder could fall out or make a hole by putting too much pressure on the wall of the nearby aorta. Recently, there have been reports of cases where the patient developed headaches or vision problems (scintillating scotoma) months or years after the surgery, so careful consideration is needed.

Surgical treatment

We can open up the right atrium and directly sew up the hole (defect) or close it with a patch. Regardless of the size or position of the hole, it is possible to close it up reliably.

ASD surgery is a simple procedure that just involves closing up the hole between the atria. In the many standard operations that have been done so far, a 20-25 cm(?)* midline incision is made in the chest, but when Team Watanabe do adult ASD surgery using the Da Vinci surgical assistant robot, we make several small holes and insert an endoscope to operate using a minimally-invasive procedure.

Why is it suitable for robot-assisted surgery?

By nature, this is a comparatively simple surgery that just involves closing a hole, the septum is soft so it is easy to suture, and it’s easy as far as heart surgery goes. Since it’s a simple surgery, we can also consider this as a method for reducing the burden on patients by not cutting a large hole in their chest, not requiring such a long recovery period and not causing postoperative pain or other symptoms.

However, from an organisational perspective, ASD surgery is not currently eligible for insurance, so I hope it will be covered soon.

Things I’d like you to know about ASD

Actually, most ASD patients have no symptoms until adulthood. Also, as patients grow older they can have similar symptoms due to arteriosclerosis, myocardial infarction, etc.

ASD is not a disease you can diagnose yourself from its symptoms, and surgical treatment isn’t possible if it’s discovered too late, so if you have strange symptoms like difficulty breathing or an irregular pulse, please go to the hospital for diagnosis.

* The Japanese text just says "20-25? incision", but I think it must mean cm.