Hey everyone, it's Sarah with RegisteredNurseRN.com and today we're going to talk about calcium channel blockers. And as always, when you get done watching this YouTube video, you can access the free quiz that will test you on this medication. So let's get started. As we've been going through these medications in this pharmacology series, we have been remembering the word nurse because this allows us to remember those important concepts we need to know about these medications for exams. So first we're going to talk about the name of the drug. We're dealing with calcium channel blockers. And just as the name says, these drugs block calcium channels, specifically the L-type of calcium channels. Now these drugs do this in three specific areas. And if you can understand the mechanism of action of these three areas that calcium channel blockers affect, Understanding calcium channel blockers is really easy. It'll make sense while you're doing the things you are as a nurse and patient education and side effects. So these medications affect the calcium channels in the vascular smooth muscle. So we're talking about the coronary arteries and the peripheral arteries, not veins. Remember those coronary arteries are those arteries that sat on top of your heart muscle and help deliver that fresh oxygenated blood that your heart muscle needs. to work and to pump. Also it affects the calcium channels in the cardiac myocytes. The cardiac myocytes are the cells that make up your heart muscle that allow it to contract. So they control like the strength of contraction. In addition, it's going to affect the calcium channels in the cardiac nodal tissue, specifically the SA and the AV nodal tissue. And these nodes play a role in the electrical impulse of the heart. The SA node is known as the pacemaker of the heart, so it controls our heart rate and it's located in this area up here. And then we have the AV node and it's like the gatekeeper of the heart's electrical impulse and it controls the speed of conduction. So let's talk about how calcium channel blockers affect vascular smooth muscle first. So calcium plays a huge role in contraction. So you have these calcium channels that allow calcium through. Whenever that happens, contraction can occur. But if we block these calcium channels, calcium can't go through. So instead of having contraction, we will have relaxation. And that is what's happening with these vascular smooth muscles, particularly the coronary arteries and the peripheral arteries. So if we're not letting calcium through those channels we're going to get relaxation, hence vasodilation of these arteries. And when we vasodilate that's going to help decrease arterial blood pressure. And when we decrease arterial blood pressure we're going to help the heart out because we're going to decrease the systemic vascular resistance. And when you decrease systemic vascular resistance you're going to decrease cardiac afterload. And remember what cardiac afterload was. This is the resistance that really that left ventricle must overcome to squeeze the blood out of the heart. So for decreasing the resistance, it's going to have to go up against, you're going to decrease really the workload of the heart and how much it really has to squeeze to get that blood out of the left ventricle. Also, because we're blocking the calcium channels in the spascular smooth muscle. We're going to cause vasodilation and allow those coronary arteries to relax. So more blood flow is going to be able to perfuse this heart. Plus, it can decrease any type of possible vasospasms that might occur on the heart. So as you can see, These calcium channel blockers are very beneficial in treating patients who have high blood pressure, hypertension, because we're dilating arteries, we're decreasing pressure, and it can help with the prevention of angina or angina, either way you want to call it, in patients who have variant angina, also known as presbyatal angina. This is angina, chest pain, that occurs at rest due to one of these coronary arteries. having a spasm. So if we give them a calcium channel blocker, that can help prevent that from occurring and relax those coronary arteries. Now let's talk about how calcium channel blockers affect the cardiac myocytes. Because remember, they're responsible for the strength of the heart's contractions. So you have this cell, it plays a role in how strong the heart can really contract. Well, we're blocking that calcium channel. So calcium can't go in there and play a role with contraction. So we're going to get weaker contractions. It's going to decrease the strength of those heart contractions, which will produce a negative inotropic effect. And this is beneficial if we want to decrease the oxygen demand of that heart muscle, which would be helpful with patients who are having angina. But it wouldn't be so helpful for patients who have heart failure where this heart muscle is already damaged. It doesn't really pump very efficiently anyways. So we really don't want to throw on a medication that's even going to make those contractions weaker. And then lastly, calcium channel blockers affect that cardiac nodal tissue by inhibiting or blocking those calcium channels. and that calcium can't get into those cells of the nodal tissue and allow them to contract and do their job and we're specifically talking about the SA and the AV node so with the SA node whenever we're blocking those calcium channels we're going to really be slowing down that heart rate because remember your SA node is your pacemaker of the heart so it controls the heart rate so if we alter how it can control the heart rate and prevent its contractions we will get a slower heart rate which will produce a negative chronotropic effect. And the AV node, whenever we're inhibiting its calcium channels, it is going to slow down the speed of conduction of electrical impulses, which causes a negative dromatropic effect. Because remember, the AV node is the gatekeeper of the heart, and it relays the electrical impulse by slowing down the impulse that it received from the SA node. So... Because these medications deal with that electrical activity of the heart, it can be beneficial in treating some patients who have dysrhythmias. And here in a moment you're going to see that certain categories of calcium channel blockers are a little bit better at treating dysrhythmias because they're more selective in how they act on this cardiac nodal tissue. And some dysrhythmias that these medications can help treat are like supraventricular tachycardias and like atrial fibrillation. And this is where you have an abnormal fast heartbeat that can arise out of that AV node. So if we can throw on a calcium channel blocker that specifically alters these nodal tissues, we can help treat that dysrhythmia. Now let's talk about the different types of calcium channel blockers and what they're used to treat. So the first type of calcium channel blockers are the dihydropyridines and these medications are a little bit more vascular selective. So they're selective to that vascular smooth muscle which is going to allow them to be able to treat high blood pressure, hypertension or angina. And some medications that are considered the dihydropyridines are medications that end in pine, p-i-n-e, so be looking for that, like amlodipine, felodipine. and nifedipine. The other type of calcium channel blockers are the non-dihydropyridines and these are more selective to that myocardium so they're more selective to the heart. They can also provide some of that vascular smooth muscle effect too so they're helpful for treating hypertension and angina but they also have that antiarrhythmic effect where they can treat those dysrhythmias and we talked about that because it affects the nodal tissue and the cardiac myocytes. And some medications that fall into this are verapamil. And verapamil is considered a phenylalkylamine. And then we have deltiazem. And this is considered a benzothiazepine. So these medications, whenever your patient's, let's say, having one of those supraventricular tachycardias, Atrial Fibulation, they can give them these medications and it can help them this category of drugs because they are a little bit more selective to that myocardium. Now some miscellaneous conditions that calcium channel blockers can treat are like Renaud's syndrome, phenomenon or Renaud's however you want to say it. or like migraines or spasms of the vessels, specifically the cerebral vessels. Now let's wrap up this lecture and let's talk about the role of the nurse, side effects, and education pieces for the patient. So some of these calcium channel blockers can slow down the heart rate. But as the nurse, we want to make sure our patient's heart rate is not getting too low. So we're going to monitor for bradycardia. And that's really with verapamil and deltiazin because remember, they're a little bit more selective to this myocardium and this cardiac nodal tissue. And they can affect the SA and the AV nodes. So we want to make sure they're not getting bradycardic. Also, we want to monitor their blood pressure, making sure they're not experiencing hypotension because all these medications... allow the relaxation of really that vascular smooth muscle which can lower your arterial blood pressure. So we want to teach the patient because they're going to be taking this at home we won't be with them we want to teach them to monitor their heart rate and monitor their blood pressure regularly and to record it. Also, we want to monitor a patient for a condition called reflex tachycardia. What is this? This is where the blood pressure drops because it does with these medications, but if it drops too low, the heart will respond as like a compensatory mechanism and increase, trying to in a sense get the blood pressure up so we can maintain cardiac output throughout the body. So that's what can happen in some patients. So we want to monitor them for that because if they do, they can prescribe. Another medication to combat that tachycardia. Also teach your patient about orthostatic hypotension because we're altering pressures in the body. So whenever they're lying or sitting, they need to get up slowly because they can get dizzy and they can fall and get hurt. Also, as a nurse, you want to monitor the patient's EKG because, especially if they're on verapamil or diltiazem, which affects this nodal tissue, we could throw them into some dysrhythmias. Some patients may develop a first-degree AV block, and that's because these medications, verapamil and diltiazem, are slowing down the conduction. of the AV node. However, these medications are contraindicated if a patient has a second or third degree block. So always look at that EKG, make sure your patient doesn't have that while they're taking this medication. Also, we want to monitor our patient for signs and symptoms of heart failure. Now, why would they be at risk for developing heart failure? Well, remember when we were talking about how these medications work, they cause a negative inotropic effect because those cells, those myocytes... that cause contraction. They're not having the calcium enter into them so they contract. So we have decrease in the strength of contractions. Well, if we do this a little bit too much, the patient may have heart failure where that heart muscle really isn't contracting very well to pump out blood. So blood is backing up, leading to signs and symptoms of heart failure. And you want to be looking at your patient, listening to their lungs. Do their lungs sound wet like they have crackles? Are they having difficulty breathing? A big thing with heart failure patients literally getting up moving around in the bed or just getting to that bedside chair they will be really winded and they'll be huffing and puffing and normally they shouldn't do that. So be looking for that. Performing daily weights, are they gaining more than two pounds a day? That can mean that they're retaining fluid or they have edema, especially in their legs. And you want to teach your patient while they're taking this medication at home to watch for those signs and symptoms as well. If they develop that, report it to the doctor. Also, the patient wants to avoid taking these medications with grapefruit juice because grapefruit juice can increase the amount of these drug levels in the body. Also teach the patient to follow a high fiber diet, especially if they're taking like verapamil or deltaezyme because these slow down GI motility, which can lead to constipation. And they want to practice good oral hygiene, especially if they're taking the dihydropyridines because these medications can cause gingival hyperplasia where you have enlargement of the gum. So they'll want to go to their dentist regularly, make sure they're brushing their teeth and having good gum care. And lastly, if your patient is taking a calcium channel blocker and digoxin, you want to monitor for digoxin toxicity. Because sometimes patients who are taking calcium channel blockers are taking them for cardiac reason, and they may also be on digoxin. So those levels of dig will really be monitored. So what are some signs and symptoms that your patient may have digoxin toxicity without looking? at their drug level? Well, some early signs and symptoms are like GI related, where they're having nausea, vomiting, or they can have vision changes where they're seeing yellowish, greenish, halos, blurred vision, and they can have dysrhythmias, which that tends to be a little bit later on. And a normal DIG level where they're therapeutic would be 0.5 to 2 nanograms per milliliter. So anything greater than 2 you want to watch out for. Okay so that wraps up this review over calcium channel blockers.