Pharm: Calcium Channel Blockers for Heart Failure & MI

Heart failure is a condition that is identified as the heart’s inefficiency to pump blood supply to various areas of the body adequately. If there is an insufficient flow of blood, all primary functions of the body are disrupted. While there are instances wherein pumping difficulties cause the heart failure, other clients suffer due to stiffening and hardening of the muscles of the heart, resulting to reduction of blood flow.

This is where calcium channel blockers come in.

Calming the Heart

Here, we are informing the sympathomimetic response of the sympathetic nervous system to calm down by instructing the heart not to contract. This is done by taking the pressure off and blocking out the stimulus.

So, there are three types of medications that you can give to achieve this, namely:

  • Alpha-blockers (Catapres or Clonidine) – has vasodilation effects
  • Beta-blockers
  • Calcium channel blockers

Calcium Channel Blockers

As mentioned, one of the main problems with heart failure is increased volume and resistance inside the blood vessels; therefore, it is necessary that this resistance is relieved through calcium channel blockers. We are basically asking the blood vessels to relax and not be tensed.

Though Nitroglycerin is given to clients with myocardial infarction, the main goal is still taking off the electrical excitability from the blood vessels so as not to strain the heart muscles.

Cellular Level

The blood vessels are like rivers that are interlinked with each other. Looking at it at a cellular level, and taking into consideration a cell, which looks like a small city. Inside this city are various structures like the city hall (nucleus), power plant (mitochondria), trash company (lysosomes), and other parts like the Golgi apparatus, and endoplasmic reticulum.

In every city or cell, there are gates that allow elements to enter or exit, like in the case of sodium-potassium exchange. Fluids and electrolytes cause cellular excitability; calcium is an example of an electrolyte that causes tensed and constricted vessels.

Calcium: Bone versus Heart

Calcium causes bones to become stronger and more durable. Calcium for the heart, on the other hand, has a similar effect because it can cause the vessels to become stiff which would add to the resistance if there’s pressure, leading to hypertension.

Mechanism of Calcium Channel Blockers

Calcium channel blockers are given to make the heart very soft and supple. Like diuretics and beta blockers, calcium channel blockers decrease the rate and the hardness.

Calcium channel blockers are medications prescribed to relax the vessels of the heart, thereby increasing the blood supply and oxygen while reducing the workload. Some well-known calcium channel blockers are:

  • Diltiazem
  • Felodipine
  • Amlodipine

Other heart conditions wherein calcium channel blockers are applicable:

  • Hypertension
  • Hypertrophic cardiomyopathy
  • Coronary artery disease (CAD)

Client Teaching

When taking calcium channel blockers, you should advise your client that this type of medication has to be taken with either milk or food. Taking of blood pressure is also necessary to monitor any signs of side effects like decreased heart rate, hypotension, drowsiness, and lightheadedness.

For clients with myocardial infarction, emergency drugs are often given aside from maintenance medications. This will be discussed in our next article. You can also visit Simple Nursing’s website and YouTube channel to check out other nursing-related topics.

 

Congestive Heart Failure & Myocardial Infarction Drugs

Are you having a hard time differentiating congestive heart failure (CHF) drugs from myocardial infarction (MI) drugs? In this lecture, you will learn how to appropriately identify which medication is given to CHF clients and which is given to MI clients.

So the main question is: What is the difference between CHF and MI drugs?

To answer that question, one must first know what’s going on between the two conditions.

Pathophysiology: Congestive Heart Failure

One of the major differences between congestive heart failure and myocardial infarction is where the complication originated. For CHF, it’s due to the ventricles inside the heart that are primarily responsible for pumping blood throughout the different parts of the body, delivering oxygen where it’s needed.

If there’s increased volume being pushed down into the ventricles, the heart tends to give up, leading to congestive heart failure. Furthermore, if there is increased vascular resistance within the vascular beds, the ventricles get exhausted and can either give up or become hypertrophic. Hypertrophy is due to swelling caused by compensation done by the ventricles.

Decreasing the Volume

To take the volume off the heart, diuretics are given. The different types of diuretics are:

  1. Loop
  2. Thiazide
  3. Potassium-sparing
  4. Osmotic

While these diuretics somehow differ in how they react, they do have the same goal – to get the load off of the ventricles.

Loop and Thiazide

Loop diuretics act on the descending loop of Henle, which means that this medication is responsible for triggering the excretion of fluid within the glomeruli.

Loop diuretics and thiazides are potassium-wasting diuretics. This information is vital especially during examinations wherein questions regarding potassium would usually come up.

Digoxin Toxicity

Clients taking potassium-wasting diuretics and who are taking digoxin at the same time, are at risk for digoxin toxicity. Digoxin is a cardiac glycoside that helps in depolarizing, for cases like atrial fibrillation. Therefore, giving potassium-wasting diuretics to clients who have a depleting potassium level will resort to toxicity because as the potassium goes down, the digoxin level will go up.

Remember, anything greater than 2.0 ng/mL, is considered as digoxin toxicity. One of the best indicators for digoxin toxicity is if the client starts seeing halos.

NCLEX® Trick Question

A tricky NCLEX® question when it comes to digoxin toxicity is:

If your client’s digoxin level reaches 1.9 ng/mL, would you give or hold the administration of digoxin?

Answer: Yes, because that is still within digoxin’s therapeutic level.

Potassium-Sparing Diuretics

Spironolactone is a popular potassium-sparing diuretic that blocks aldosterone in the kidneys while keeping potassium inside the body. Aldosterone or Aldos-“Tyrone” can be considered as the bouncer that is responsible for the regulation of the renin-angiotensin-aldosterone system (RAAS).

A good nursing question for potassium-sparing diuretics would be:

A client is going to be placed on a potassium-sparing diuretic, what should be the nurse’s client teaching?

Answer: Tell the client to eat a normal, healthy diet but should avoid potassium-rich foods like spinach, bananas, and green leafy vegetables.

Osmotic Diuretics

Mannitol is the popularly known osmotic diuretic that is usually given to a client with increased intracranial pressure. Osmotic diuretics help in withdrawing all excess extracellular fluid from the brain down to the potty.

On our next discussion, we will tackle further about myocardial infarction and its medications.

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!