Acute Coronary Syndrome: Stable vs Unstable Angina

When dealing with stable and unstable angina, what you have to keep in mind is that both are due to low oxygenation of the heart. Angina technically means chest or heart pain.

Vasoconstriction versus Vasodilation

If a client has coronary artery disease (CAD) which is caused by high cholesterol, there is increased plaque formation within the lining of the blood vessels, and this causes the passageway to get constricted.

When a person becomes physically active or is caught up in a stressful situation, the fight and flight response is activated by the sympathetic nervous system. Once this happens, the blood vessels shrink and go into vasoconstriction. On the other hand, when a person is relaxed, like resting on a beach somewhere, vasodilation occurs. During vasodilation, rest and digest are activated.

Why Blood Vessels Constrict

When the body is exerting effort doing strenuous activities, the blood vessels constrict, and the heart rate and blood pressure increases.

The blood vessels constrict to increase oxygen delivery to the vital parts of the body like the heart, lungs, and brain. There is increased blood pressure and heart rate because the body is shunting all that oxygen into the blood vessels where it’s needed most.

Stable Angina

Stable angina is also known as the exercise-induced chest pain. This means that whenever a person exercises or does physical exertion, the plaque or inflamed vessels become very narrow which causes decreased oxygen delivery to the heart. The moment the person stops what he or she is doing, the chest pain also goes away, and breathing would go back to normal.

Unstable Angina

On the other hand, unstable angina happens when a person still experiences pain even after stopping a stressful physical activity. The blood vessels have expanded, but the pain has remained consistent. This is most likely a case of unstable angina which means that there is a blood clot that’s blocking the coronary artery.

Why does this happen?

When a person is exercising, the blood vessels shrink or become smaller to adequately and effectively deliver oxygenated blood to the vital organs in the body. As the body relaxes, the blood vessels expand, there will be tiny clots or platelets that are attached to the edges of the plaque, occluding the entire vessel.

So just a reminder, stable angina is relieved by rest while unstable angina still causes chest pain even during rest.

Unstable Angina Pharmacology

Since unstable angina is not relieved by rest, the suspected client will get started on MONA – morphine, oxygen, nitrogen, and aspirin.

MONA is a type of recipe or what is otherwise known as a core measure or best practice that the United States or the governing bodies of different hospitals have come up with. MONA has shown promising results to decrease events that can lead to death.

MONA is actually given as ANOM. How?

  1. Aspirin – is the first recipe that will be given to the clients to thin out the congregated platelets. Aspirin will break up the platelets to make sure that they will not form around the plaque.
  2. Nitrogen – is given for vasodilation or vaso-expansion.
  3. Oxygen – is given after vasodilation.
  4. Morphine – is the last recipe to be given, especially if the top three recipes weren’t able to take the chest pain away. Morphine is given last to determine if the client is experiencing myocardial infarction because if after administration of morphine and the client is still in pain, this would mean that the client is going to have a heart attack.

In our next lecture, we will focus on the different tests and studies done to determine a heart attack.

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Easy-to-Understand Myocardial Infarction Pathophysiology

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Today, we’ll be talking about the pathophysiology of myocardial infarction (MI) and the different therapeutic modalities concerning the condition.

MI as Traffic Accidents

Think of your myocardial infarction as one huge traffic jam inside the heart that’s causing blockage to the highway, impeding the circulation of blood and oxygen. Since there’s blockage, no cars (red blood cells) are getting through to oxygenate the heart.

Keep this concept in mind while we move on with our discussion to have a clearer and better understanding of what really happens with a client who has a myocardial infarction.

Basic Knowledge

We will have a quick stop with anatomy and physiology before getting into the details of what it means to have a myocardial infarction and how it can be treated.

The heart is composed of coronary arteries that are mainly responsible for feeding the heart with sufficient amount of oxygen. Therefore, the coronary arteries are the freeways or highways of the heart.

To sustain life, oxygen must circulate adequately to and from the heart. For this reason, people who are unable to receive enough oxygen due to life-threatening circumstances like drowning manifests cyanosis and dies in six minutes due to the inability of tissues to receive oxygen. This is what pretty much happens with myocardial infarction.

When the coronary arteries (highways of the heart) are occluded for some specific reason, backup and congestion are expected which may lead to a series of heart ailments.

Stable Angina

Stable angina is basically a pain in the heart occurring activities like exercise. When the sympathetic nervous system kicks in, it causes vasoconstriction which is basically the narrowing of blood vessels leading to inefficient oxygen distribution. The pain felt with stable angina is relieved by the rest because oxygen is now properly going to the apex of the heart.  

Unstable Angina

Unlike stable angina which is caused by vasoconstriction, unstable angina is caused by a blockage.

When dealing with unstable angina, what are the things that you need to provide?

  1. Nitroglycerin is given to promote vasodilation. This means that nitro is given to basically add more lanes to the freeway so that there is sufficient perfusion of blood and oxygen going to the apex of the heart.
  2. Aspirin 325 mg is given due to its anti-platelet property. Aspirin helps the blood to go around smoothly around the clot or whatever is obstructing oxygen flow.
  3. Morphine is another treatment modality that one should consider when taking care of a client with MI. Morphine is mainly given to relieve the pain stressing the heart.

If the pain is not relieved, unstable angina can lead to myocardial infarction or tissue death.

Why is there tissue death inside the heart? Due to lack of oxygen received by the tissues. It’s like tightly putting a tourniquet around your finger for about six minutes or so, causing the distal portion to become cyanotic and the chances of losing that finger are high. The tissues of your finger die because of the absence of oxygen. This is similar to MI.

  1. Give a beta-blocker or heparin drip. While heparin is not necessarily the medication responsible for cleaning up the heart from clots, it prevents further accidents or blockages from happening. A heparin drip is an anti-coagulant which contributes to lesser clamping inside the blood vessel.

So, that’s basically what a nurse should do in cases of myocardial infarction.

On our next topic, we’ll show what MI looks like on an EKG strip and provide you with further information about the condition.

See you there!