UNSTABLE ANGINA - NSTEMI
Previously: Coronary heart disease; angina
The heart is a muscular pump responsible for blood circulation. It is the engine of life.
The coronary arteries
This muscle is fuelled by oxygen, which is delivered by coronary arteries that run along it and penetrate it.
There diameter varies between 2 and 4mm.
Any alteration to the lumen, or diameter, of these vessels can compromise the heart’s functioning and even affect it permanently.
Three principals types of alteration
Three types of serious alteration can hinder coronary circulation. All three begin in the muscle layer, the media:
1. A spasm of the artery, either spontaneous or provoked by a substance such as cocaine. A coronary spasm is the contraction of the media’s muscle layer, which strangles the vessel. The consequences of this strangling will depend on the severity of the spasm, i.e., on whether the closure of the artery complete or partial as well as on the spasm’s duration.
2. The spontaneous dissection or tearing of the media. The cause is still not well understood, but it is thought that it could be related to an anomaly in the media. Once again, the consequences will depend on the severity of the vessel’s interior tear and whether it completely or partially obstructs the inside of the artery.
3. The rupture of an atheromatous plaque, better known as a cholesterol plaque. This is by far the most common cause of alteration in coronary circulation.
Let us examine the third type more closely.
By far, the most common cause of acute alteration that can inhibit coronary circulation is the rupture of an atheromatous plaque, better known as a cholesterol plaque. These plaques accumulate in the arteries’ muscle layer, called the media, and can break open spontaneously.
When a plaque ruptures, the body launches a process to fix the breach created by the rupture, beginning with the activation of blood platelets.
It is a “911” for platelets
Platelets are small particles that are found in the blood. More specifically, they are small pieces of large cells that are found in the bone marrow. They play an important role in blood coagulation, the process that stops bleeding.
When we cut ourselves, we bleed. The blood runs because there is a breach in the blood vessels. The organism sets off an alarm signal, like a 911 call, to cover or close the breach. This is what coagulation does.
The platelets are the first cells to enter into action.
When they come into contact with elements under the fine layer of the intima, the platelets change form, produce tentacles and stick together. They form the clot’s primary structure.
They also release substances that attract other platelets and activate the coagulation process by transforming certain blood proteins into small filaments.
The accumulation of these filaments around platelets and trapped red blood cells forms a net that further solidifies the clot and seals the wound.
The same process in coronary artery
The same process occurs when a cholesterol plaque creates a breach in the coronary artery by rupturing. The forming of a clot in a coronary artery can have two results: a partial obstruction or a complete obstruction of the blood vessel.
This vascular event in the coronary artery can have heavy consequences.
Partial obstruction of the coronary artery
In the case where the clot partially obstructs the coronary artery or one of its branches, the cardiac muscle it feeds still receives oxygen, but in potentially limited quantity.
This situation is unstable, this is unstable angina, now called NSTEMI.
A clot formation in the arteries, like in any other blood vessel, is a dynamic situation.
The body has a blood coagulation system, but it also has a blood clot dissolution system. The two mechanisms usually work in harmony. The first serves to stop up a breach in a vessel, and the second regulates its amplitude. These two mechanisms are like the yin and the yang. In constant interaction, they can vary the size of the clot.
Moreover, small pieces of the clot can detach and end up further down in the artery’s branches, causing small distal obstructions.
This fluctuation causes symptoms that can vary with time. In a classic case, chest pain and discomfort come and go in the form of multiple episodes of varied duration and intensity, either as a result of strain or not.
This situation is unstable. The artery could become completely blocked at any moment. It is a cardiac emergency!
You should consult a healthcare professional promptly in this situation and ideally make your way to the emergency room.
Treatment of unstable angina
The usual treatment for unstable angina aims to reduce blood coagulation and thus slow the formation of clots in the coronary arteries.
The doctor prescribes a medication to inhibit platelets and another to significantly slow down the coagulation process that leads to the forming of fibrin.
These small filaments stick together to form a net that solidifies the clot with platelets and red blood cells trapped inside.
The second step is usually to perform a coronary angiography and possibly an angioplasty, which is a non-surgical intervention to repair the coronary artery responsible for the symptoms.
What is a coronarography
A coronarography is an examination of the coronary arteries.
This exam is done under local aesthetic, although a sedative is also given to increase the patient’s comfort level during the procedure.
How they proceed
The patient lies on an exam table with a device above him or her including a camera to record images from different angles. A puncture must first be made into the artery of the thigh or wrist, which will serve as an “entryway” for the catheters, which are thin plastic tubes.
The rest of the exam is usually painless.
The catheter reach all the way to the heart’s arteries to directly access the affected vessel.
An iodine-based liquid is injected to colour the arteries so they are visible on an x-ray. Once they are visible, the artery responsible for the unstable situation can be identified.
Repair of the artery by balloon and metal prosthesis
If the situation permits a coronary angioplasty, the doctor will perform it immediately. The patient is always kept informed of the situation.
Coronary angioplasty repairs coronary arteries with the help of catheters. A catheter is placed at the entrance to the coronary artery in need of repair or that leads to the branch in need of repair. The catheter transports the material used for the repair.
A small metal guide wire acts as a "railway"
A very fine metal wire is inserted into the coronary artery to penetrate and break through the lesion.
This wire acts as a railway to carry materials in the affected artery.
A balloon catheter is brought through the centre of the clot in order to dilate the partial or complete obstruction. Once in position, the balloon is inflated. The plaque and the clot are crushed against the wall, leaving a bigger opening for blood to flow through once the balloon is deflated.
For better results in the short, medium and long term, a stent is usually placed at the site of the residual blockage.
It is a metal implement that looks like a spring.
The stent is put into place by a balloon catheter that transports it folded. When the balloon inflates, it opens the stent and presses it against the vessel wall. The balloon is then deflated and removed, leaving the stent in place forever.
Some stents are covered with medication that helps diminish the risk of recurrence at that location.
Not rejected by the human body
The stent is not rejected by the human body. However, it is a foreign body capable of stimulating platelet activity and the mechanism responsible for forming clots.
To avoid thrombosis
To avoid such a thrombosis, the doctor prescribes a combination of medications to take every day.
Aspirin must be taken for life, while the second antiplatelet medicine prescribed is taken for a year and sometimes for life.
The cells of the human body will completely cover the stent in the weeks or months following implantation.
Never stop your pills that protect the stent
One should never stop taking prescribed antiplatelets without consulting a cardiologist, even for a minor surgical procedure. Stopping medication could put the patient at risk of serious and potentially fatal consequences. In fact, failure to take one’s antiplatelet medication is the primary cause of sudden stent thrombosis.
“Open heart” surgery
In some cases, arterial repair may not be possible through angioplasty due to the quantity, complexity and location of the blockages.
Revascularization through a surgical procedure, commonly known as bypass surgery, is often possible for certain patients in this situation.
The “pills” option
In those for whom neither angioplasty nor surgery is possible, the only option is medication.
Two categories of treatment
During hospitalization for unstable angina or an infarction, the doctor prescribes two categories of treatment, one pharmaceutical and the other non-pharmaceutical.
Pharmaceutical therapy, in addition to antiplatelets, helps the heart work better and controls blood pressure as well as cholesterol levels. Remember that on top of this, aspirin must be taken for life.
The non-pharmaceutical therapy is just as important, if not more so.
The patient will have to make some lifestyle changes to reduce the risk of new cardiac events in the future. He or she must quit smoking, eat healthfully, lose weight, exercise regularly and monitor cholesterol levels and blood pressure.
One of the best ways to start this therapy is to exercise regularly. It is recommended to do 30 minutes of cardiovascular exercise 4 to 7 days a week. Improved blood pressure is rapidly perceptible with exercise. Walking is a good way to get used to exercising, since this activity is accessible to all and costs nothing.
Regular exercise often leads to a change in dietary habits. This lifestyle change makes achieving or preserving ideal weight easier and reduces waist size. It is recommended to eat more fruits and vegetables, cereals and fibre and to avoid trans fats.
Ideal weight is equivalent to a body mass index (BMI) of less than 25. Men should aim for a waist circumference below 40 inches, and women below 35 inches.
Quit smoking if you do
Just as regular exercise usually leads to improved dietary habits, it often leads to the realization that smoking doesn’t fit with this new lifestyle. It is an excellent opportunity to make the important decision to quit smoking.
Consumption of alcohol
It is also recommended to reduce your consumption of alcohol. For men, a little less than two alcoholic drinks per day is acceptable, whereas for women, a little more than one alcoholic drink per day is acceptable.
One alcoholic drink is equivalent to one beer, one glass of wine or an ounce and a half of spirits with a 40% alcohol content.
This non-pharmacological therapy is easy to consider, but not necessarily easy to adopt, since it requires changing several habits. However, it is very beneficial, and professionals can help you make these changes.
No one is safe
No one is safe from coronary artery disease. We must be vigilant, for ourselves and for the people around us, and know the signs and symptoms as well as the aggravating factors.
Prevention is always the best treatment.
Next chapter: Myocardial Infarction
Read more: Life after myocardial infarction