Antihypertensives: Beta Blockers Part 3

After going through the different kinds of volume depletion drugs, we’ll be discussing what beta-blockers are. Beta-blockers are commonly given to hypertensive clients to manipulate the conduction system of the heart.

Decreasing Blood Pressure

There are a couple of ways to lower blood pressure. First is taking off the workload by decreasing the fluid volume, through the use of diuretics and ACE inhibitors. And the second is to decrease the rate of conduction inside the heart through the use of beta-blockers.

Defining Beta-blockers

Beta-blockers are negative chronotropic drugs that block the SA node of the heart increased, inappropriate contractions. But how do beta-blockers work?

Beta-blockers block the beta-adrenergic receptors – beta-1 and beta-2. Beta receptors can be found either in the heart or the lungs. Beta-1 receptors can be found in the heart, while beta-2 receptors are inside the lungs. To easily recall this information, beta-1 is for the heart because there’s only one heart; on the other hand, beta-2 is for the lungs because there are two lungs. In the case of beta-blockers, they block receptors found inside the heart that triggers accelerated contractions.

Beta-Blocker Mechanism

If beta-2 is stimulated by giving a client beta-2 agonist, this will cause bronchial dilation. However, if beta-2 is provoked, beta-1 is also triggered; meaning, the heart rate will rise, leading to tachycardia. This is the reason why clients who are receiving treatment for breathing problems have increased heart rate. So, beta-blockers technically decrease heartbeats.

The “-Lol” Drugs

Beta-blockers end in “-lol,” like laugh out loud. Some popular examples are atenolol and metoprolol.

What to Watch-Out-For

There are four Bs that healthcare providers need to be aware of when administering beta-blockers. What are these four Bs?

  1. Bradycardia

Bradycardia means that the heart rate has dropped to less than 60 beats per minute. Obviously, the aim for giving beta-blockers is to slow down the client’s heart rate, but not to kill the client by continuously administering anti-hypertensive drugs. Therefore, to determine if it is safe to give beta-blockers to a client who is taking several anti-hypertensive drugs, blood pressure must be taken.

Since beta-blockers affect the beta receptors in the heart, there will be no direct effect on blood pressure, but it is essential to observe the client’s trend or status.

So, how are anti-hypertensive medications given?

Give the client the least heavy dose first. Meaning, volume depletion medications must first be given before messing with chronological or electrical conduction drugs. Some volume-depleting drugs are:

  • Diuretics
  • ACE inhibitors
  • Angiotensin II receptor blocker (ARBs)

Major nursing exams and the NCLEX® tend to ask trick questions that are related to this kind of dilemma. Remember that if the scenario is questionable, the answer is most probably to hold the next dose of anti-hypertensive.

  1. Decreased blood pressure

Another side effect of beta-blockers is depreciating blood pressure. As mentioned, beta-blockers do not directly affect blood pressure; however, since it influences stroke volume resulting to decreased cardiac output, there is a possibility of decreasing blood pressure as well.

  1. Bronchoconstriction

This might be a bit confusing, but the logic behind this side effect is that anytime beta-1 is blocked since it’s non-specific, beta-2 is also blocked. If albuterol is given, there is a probability of causing an increased pulse rate.

  1. Blood sugar

Beta-blockers interact with insulin release, masking the signs and symptoms of low blood sugar and bradycardia.

To check out our previous beta-blocker lectures, and to find out more nursing-related videos, drop by our Simple Nursing website and YouTube channel.

Emergency Meds: Antidysrhythmics & Beta Blocker Differences

In this section of, we’ll be looking at two types of emergency medications – antidysrhythmics and beta blockers – and whether they’re inotropic, chronotropic, or dromotropic.

Let’s begin.

Antidysrhythmics

Amiodarone is a popular antidysrhythmic medication that has negative chronotropic effects and dromotropic effects. How does this happen?

Antidysrhythmics as a Negative Chronotropic

Antidysrhythmics are considered as a negative chronotropic because they can effectively bring down the heart rate. By targeting the SA node, antidysrhythmic drugs influence the contraction and conduction of electrical impulses. Since amiodarone is a negative chronotropic drug, its purpose is to decrease the electrical impulses coming from the AV node as well.

So, when a client is experiencing a detrimental rhythm, like ventricular fibrillation, the priority is to get them out of that state by providing chemical cardioversion in the form of Amiodarone or antidysrhythmics. After giving Amiodarone, the client will be given subsequent shocks using a defibrillator to restore the heart’s normal rhythm.

The main goal of antidysrhythmics is to decrease the heart rate because when a client has an irregular rhythm, the heart is going so fast.

Antidysrhythmics as a Negative Dromotropic

Since antidysrhythmics are focused on getting the electrical impulses down, they are also considered as negative dromotropic.

On the other hand, antidysrhythmics don’t have inotropic properties.

Beta Blockers

Beta blockers are non-specific medications that block the beta from the system. Beta blockers are those drugs that end in “-lol.” Some popular generic names are Atenolol and Metoprolol. As for some brand names, Lopressor is a widely known brand, as well as Coreg.

Beta blockers block beta receptors of the heart and lungs. To remember which beta blocker is given to the heart and lungs, you just have to keep in mind that beta 1 refers to the heart because there’s only one heart; while beta 2 is given to the lungs because there are two lungs.

Side Effect

A typical side effect that nurses have to watch-out-for when giving beta blockers to clients is that, aside from being anti-hypertensive drugs, they are also anti-rate drugs. This means that beta blockers are non-specific that even if the intention to give the drug is to block the increased heart rate, the agonists used for breathing are also blocked. Therefore, the client is expected to have decreased respiration.

Beta Blocker as a Negative Chronotropic

Since beta blockers decrease the heart rate, it is considered as a negative chronotropic drug because of the primary goal of decreasing the heart rate.

Beta Blocker as a Negative Dromotropic

On the other hand, beta blockers are also considered as a negative dromotropic because they block electrical conductivity inside the heart, telling it to slow down and stabilizing the electrical impulses; thus steadying the rhythm. This is similar to telling the SA and AV nodes to calm down.

The Different Mechanism of Action

Antidysrhythmics and beta blockers are different regarding the mechanism of action in bringing down the excitability of the electrical impulses which results in bringing down the heart rate.

Antidysrhythmics affect the SA and AV node directly; while beta blockers affect the beta receptors.

So, that’s basically the huge difference between the two drugs, but their goal is similar.

In our next lecture, we’ll be tackling calcium channel blockers and cardiac glycosides (Digoxin). 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!

Antihypertensive Drugs: A Closer Look at Beta-Blockers

Beta-blockers are, in the simplest sense, heart medications for clients with hypertension that is mainly focused on the conduction system of the heart.

Just to refresh your memory, there are two ways to lower blood pressure.

  1. Relieving pressure from the pipes by decreasing fluid volume. These are your ACE inhibitors and diuretics.
  2. Decrease rate of conduction in the heart. These are your beta-blockers and calcium channel blockers.

Mechanism of beta-blockers

Beta-blockers are negative, chronotropic drugs that block that SA node from contracting excessively. Beta-blockers block the beta-adrenergic receptor also known beta-1 and beta-2. Beta-1 are receptors in the heart stimulates increased heart contraction. If stimulated, these beta receptors can cause contraction at higher rates. Similarly, this concept applies to beta-2 in the lungs.

Study tip: Beta-2 is for the lungs (since you have two lungs) and beta-1 is for the heart (since you have one heart)

Beta-2 agonist causes bronchial dilation. One typical example is albuterol. Dosing someone with albuterol will antagonize beta-2. However, it will also affect beta-1 which means that there will be a noticeable rise in your heart rate. This is the reason why treatment of beta-2 causes tachycardia in clients.

Beta-blockers block beta. Beta excited the heart. When the beta is blocked, the heart rate decreases. It’s as simple as that. Cool!

Beta-blockers make you LOL

According to the FDA, identification of these types of drugs must be through their suffix. One of the easiest ways to identify your beta-blockers is to know, by heart, that it can make you laugh out loud (LOL). Meaning, beta-blockers generic names end in –lol. A typical example is atenolol and metoprolol. 

Beta-blocker warnings – the 4 Bs

When giving beta-blockers to your clients, you have to watch out for these adverse effects.

Bradycardia

This is a condition wherein the heart rate of your client drops below 60 per minute. Yes, the goal of beta-blockers is to slow down the heart rate but that doesn’t mean killing your client in the process.

In giving anti-hypertensives, it is advised to give the client the least heavy doses first. Meaning, give your volume depleters first; this will be your diuretics, ACE inhibitors, ARBs, and potassium-sparing diuretics. Don’t opt for electrical or chronological conduction drugs until you have given the volume-depleting drugs and have thoroughly assessed your client’s vitals.

This thought is going to be very useful during exams with borderline, tricky questions. Remember, the most likely answer is holding the drug if the systolic pressure drops to 100.

Blood pressure is decreased

If you’re going to administer a couple of anti-hypertensive drugs, make sure that you ask yourself how safe is it to give. Always run scenarios inside your head especially in terms of the possible out if you gave beta-blockers with other anti-hypertensive drugs. Getting the blood pressure is the best way to assess the necessity of administering the drug. If the blood pressure has significantly dropped after an hour or so, chances are, you won’t be giving the drug.

Yes, we have mentioned that beta-blockers do not decrease blood pressure and only affects Beta-1 in the heart; however, if the stroke volume is decreased, the cardiac output is decreased as well. Low blood pressure is a possible side effect.

Bronchi constriction

Yes, it was mentioned that beta-blockers are for blocking Beta-1; however, there is a probability that Beta-2 can also be blocked. Though it may be specific, it can happen.

Blood sugar masking

If your client has low blood sugar, beta-blockers can mask the signs and symptoms of bradycardia.