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.

 

What are Calcium Channel Blockers?

We did a couple of videos and articles discussing calcium channel blockers. But here, we’ll solely focus on calcium channel blockers as a negative chronotropic drug.

So, the primary goal of calcium channel blockers is to stop the depolarization or the contractility of the vessels of the heart, bringing the organ to a relaxed state.

Calcium Channel Blockers as a Negative Chronotropic

One of the notable characteristics of calcium channel blockers is that these drugs act as a negative chronotropic which is mainly focuses on the heart rate. Negative chronotropic drugs cause decreased electrical stimuli but do not deplete volume.

The “-Pine” and “-Zem” Drugs

An easy way to identify calcium channel blockers is to remember drugs ending in “-pine.” Most of the calcium channel blockers like Amlodipine (Norvasc), Nifedipine (Procardia), or the most popular, Diltiazem or Cardizem which is another popular drug used in hospitals.

The Indications

Clients who have experienced myocardial infarction or heart attack are given calcium channel blockers to soften up their hearts and relieve it of its hard contractions. Basically, we are also preventing the client’s potential to go into a hypertensive crisis. Calcium channel blockers are the best standard of care when dealing with heart attack clients.

Crucial Pointers

There are a couple of important things that you have to remember when administering calcium channel blockers or taking care of clients who are getting the treatment.

Check the BP and HR

Two of the most important things that nurses have to consider before giving calcium channel blockers are the client’s blood pressure and heart rate. It is advisable to check these two factors at least 30 minutes before the drug is given. Why?

A good example would be this hospital scenario:

A client has a low blood pressure of around 105/50. The client is supposedly getting blood pressure medications because her BP has been trending with a 105 systolic pressure for three days. Typically, the doctor will order blood pressure medications to decrease the client’s chances of going into hypertensive crisis.

Upon checking the blood pressure in the morning, the blood pressure is now up to a 115 systolic pressure so, as the nurse in charge, you will take note of that. With that BP, there is no need to withhold the drug. However, an hour or 30 minutes before the drug was given, the BP dropped to 82/40. So, the blood pressure medication will not be given at that moment.

The scenario provided above is a typical situation with hypertensive clients. For this reason, it is important to check the blood pressure and heart rate before giving any anti-hypertensive medications.

Take note: If you somehow obtained a bad vital sign reading with the client’s blood pressure, you have to retake using the other arm.

Low Blood Pressure

If a hypertensive client’s BP significantly drops, you should:

  • Withhold the medication
  • Inform the doctor
  • Put the client in Trendelenburg position
  • Advocate for an IV bolus to incorporate more fluids to the client
  • Re-check the blood pressure

Only hold the medication if the client’s blood pressure drops below 100 systolic pressure.

With or Without Meals?

Unlike other medications, calcium channel blockers are always given with meals. Food helps in the proper absorption of the medication.

That’s the end of our calcium channel blocker lecture. Our next one would focus on diuretics. Check it out on our SimpleNursing website and YouTube channel.

Quick Overview of Heart Failure Pharmacology

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We’ll be having a quick congestive heart failure review and we’ll also go over the drugs involved in treating the condition.

Antihypertensive drugs are responsible for relieving pressure that’s being set on the heart. The aim is to basically get the heart pumping normally that it can stretch and squeeze to eject and distribute blood to different parts of the body with as little effort as possible.

Congestive Heart Failure

In congestive heart failure (CHF), there is a lot of pressure from the peripheral veins that is being pushed on the heart. A primary cause of CHF would be increased sodium in the diet. Fortunately, there are tons of medications that can take this pressure off of the heart and promote proper blood flow.

What are the drugs that help in alleviating the pressure from the heart? These drugs are categorized into A-B-C-D. What does each letter stand for?

The Drugs for Heart Failure

A is for ACE Inhibitors

ACE inhibitors act on the renin-angiotensin-aldosterone system (RAAS) in the kidneys, which are responsible for bringing the pressure from the peripheral veins and blood vessels to decrease the pressure experienced by the heart.

B is for Beta-blockers

The basic function of beta-blockers is to block the beta receptors that have sympathetic nervous system response. And since the response is sympathomimetic, it’s basically the fight or flight reaction of the body which causes increased blood pressure and heart rate.

Blocking the beta receptors will result in relaxation of the heart, resulting to decreased blood pressure and heart rate.

C is for Calcium Channel Blockers

At SimpleNursing.com, there is a separate video about calcium channel blockers showing a detailed instruction on how calcium affects your body and, specifically, your heart.

So, when you think of calcium, the first thing that would come to mind is, it’s mainly found in the bones and is required for hardening the bone structure. That said, if there is an overload of calcium, the heart will be directly affected, causing it to harden. And if that happens, it will be very difficult for the heart to stretch and squeeze blood to the different parts of the body. Therefore, calcium channel blockers block the channels responsible for heart calcification, bringing back the normal function of the heart.  

D is for Diuretics

You can think of diuretics as the agents that open up the faucet inside your body – the faucet being your kidneys. And because the urinary tract primarily functions to excrete fluid from the body, it is imperative that the kidneys are properly working to relieve the heart of unnecessary pressure due to fluid overload.

Diuretics are effective in opening up these faucets (kidneys) to release toxins and fluids out of the body. Some of the main examples of diuretics are Lasix and hydrochlorothiazide. By decreasing the amount of blood or fluid that is going inside the heart, diuretics reduce stress and workload of the heart. Diuretics are basically calming down the increased pressure being pushed on the heart to the point of normalcy.

On our next discussion, we’ll take an in-depth look at the mechanism of action of ACE inhibitors, beta-blockers, calcium channel blockers, and diuretics.

You can drop by SimpleNursing.com and gain access to tons of topics that will help you pass major nursing exams and your NCLEX®. See you there!

Effects of Calcium Channel Blockers as Negative Chronotropic Drugs

When someone says “calcium channel blockers,” the first impression that would come to mind is that it blocks the channels responsible for calcium absorption. Yes, that’s what calcium channel blockers primarily do. But the question now is, how and why?

Before we dig deeper into calcium channel blockers, here’s a quick trivia question related to cardiac glycoside medications. One of the biggest questions that usually appear on nursing exams is:

Q: A client comes in complaining seeing halos, mostly green halos, what is the client experiencing and what is the nursing intervention?

A: Digitalis or Furosemide toxicity, monitor potassium.

This is especially a common inquiry on cardiac tests. Nurses need to monitor potassium for heart failure clients on Lasix, Furosemide, or other loop diuretics that wastes potassium.

So, that’s a bit of a refresher question that you should remember.

Now, let’s go into your calcium channel blockers.

The Cellular Channel

One should understand that calcium channel blockers act directly on the channels of the cells.

So, what are these cellular channels? If you wish to know more about the basics structure of the cell in a simplified manner, simplenursing.com has a video of Mike explaining the cells effortlessly, comparing it to a city that has the following structures:

  • The gates (channels)
  • A city hall (nucleus)
  • Bills and laws (DNA and RNA)
  • A post office (Golgi apparatus)
  • Power plants (mitochondria)
  • Trashmen (lysosomes)

Check that video out; it takes the stress off of memorizing the cellular structure and just have some fun working through the cell.

Calcium Channels

The cell’s city gates have channels, these channels are primarily responsible for letting things inside the cells and one of which is calcium.

Calcium is not bad for the body, especially the heart. However, if the client has hypertension, that’s when increased calcium consumption becomes dangerous since calcium is an electrolyte that causes electrical excitability or the state of being excited. So, calcium causes muscle spasms or constrictions.

That’s when calcium channel blockers come in – to block the channels so calcium won’t enter the cells and preventing spasms from occurring.

Calcium and Hypertension

On application, we can make sense of calcium by thinking about what calcium does to the body. The calcium deposits of the bones contribute to its hardened structures. Therefore, if you have increased calcium in your cells, the blood vessels become hard, and if that happens, the heart compensates by increasing the pressure to push on the hardening vessels. This is the reason why we need to block calcium from entering the cells – to soften the vessels and decrease hypertension.

So, calcium channel blockers:

  • Do not cause a force on the heart
  • Is a negative chronotropic drug – decreases the rate of contraction
  • Causes decreased cardiac output
  • Ceases arterial spasms (softening things up)
  • Causes vasodilation
  • Is not a dromotropic drug on the AV node level

So basically, calcium channel blockers are decreasing the rate regarding SA node output and electrical excitability. The direct mechanism of calcium channel blockers on the vascular beds is to block those electrolytes from getting inside, thereby softening the heart.

Critical Thinking Question

How do calcium channel blockers affect EKG readings?

Hypercalcemia causes sluggish ST waves which are just fancy terms for the heart becoming very hard and is not relaxed. Increased calcium causes increased constriction and excitability; therefore, it would show that there will be:

  • Sluggish or too much ST contractions
  • The absence of a good T-wave
  • No repolarization
  • ST elevation

This, however, does not necessarily mean that the client is having a heart attack or a STEMI, it just means that there is too much calcium. Blood tests and EKG readings are important to draw cardiac enzyme and to make sure that the client is not experiencing myocardial infarction (MI).

Simplenursing.com has tons of videos that primarily focuses on EKG readings that can immensely help students to be familiar with the P, T, and QRS waves. So, might as well check that out.

Antihypertensive Medication: Calcium Channel Blockers – Part 2

Calcium channel blockers are antihypertensive medications that technically reduce hypertension or blood pressure; thus, relieving stress from the heart.

How does one quickly spot a calcium channel blocker?

More often than not, calcium channel blockers end in “-pine.” Not to be confused with another antihypertensive medication known as beta-blockers that end in “-lol.” The most popular calcium channel blocker used in a hospital setting, which doesn’t end in “-pine” is Cardizem (Diltiazem). Cardizem drip is given to clients who have significantly high blood pressure and suffers chronic stable angina or chest pain.

Anatomy of the Heart

How do calcium channel blockers relieve the pressure on the heart that results to smooth contraction? All your questions will be answered momentarily but first, let’s do quick anatomy and physiology of the heart.

The heart’s primary responsibility is to pump blood. Think of the heart as a pumping station that pumps fuel to a car, the car is your body. Blood is composed of nutrients as well as oxygen. If the heart is dysfunctional, blood will not be sufficiently pumped, and the organs will malfunction which leads to the deterioration of the system.

Now, the veins vacuum deoxygenated blood into the heart to be re-oxygenated while the arteries send oxygenated blood away from the body. So remember:

  • Veins – Vacuum
  • Arteries – Away

The left ventricle, one of the main chambers of the heart, is the chamber that is mainly responsible for pumping oxygenated blood throughout the entire body. For this reason, the left ventricle is the thickest and the largest chamber of the heart.

If the peripheral vessels (arteries) are stiff, this causes the left ventricle to push hard against the resistance. If this happens, a lot more energy is required, and the left ventricle exerts more stress to pump more blood into the system.

If there was less resistance, the heart does not suffer. The tendency is for the heart to push as much as it can just to suffice different parts of the body with the blood it needs to function correctly. To lessen the strain on the heart and bring the blood pressure down, you need your calcium channel blockers.

How does calcium works inside the body?

Blood vessels are composed of epithelial cells. Imagine that every cell operates as a city – it has walls, a city hall, a cleaning or trash department, a post office, and gates. The central area that we will be focusing on is the city gates which are known as “channels” of the cell. The primary functions of these barriers are:

  • Break down enzymes
  • Allow enzymes into the cell
  • Releases enzymes from the cell

One of the main channels that you want to block in cases of hypertension is calcium. Why do you want to prevent calcium from coming inside the cell? This is because calcium is a mineral that contributes to the following:

  • Cellular connection
  • Blood clot
  • Muscle contraction
  • Nerve function
  • Teeth and bone strength

Calcium hardens the cells which then makes the arteries rigid. Increased cardiac output and stroke volume are two identifiers that the left ventricle is putting a lot of effort to pump blood into the stiff vessels.

Mechanisms of calcium channel blockers

This is where calcium channel blockers come in. Calcium channel blockers prevent calcium from entering the cells which lessens the cell’s hardness thereby making the blood vessels or the highways of the heart more flexible. It is now easier for the left ventricle to push blood out of the heart and into the vessels resulting to lower blood pressure.

For those who haven’t had a copy of the Pathophysiology Bible, get yourself a copy now. It contains more 70 concept maps that you can utilize for your clinical days. Concept maps vary from nursing outcomes, interventions, signs and symptoms, and pathophysiology of the Top 70 diagnoses of common admissions inside the hospital. With the Pathophysiology Bible, your study time will be cut by 200%.

For our next discussion, we will be tackling Nitroglycerin and vasodilators. See you on our next lecture!