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Patient 1

Situation: Lloyd, a 48-year-old male patient consults his primary care physician for a routine physical.

Background: Lloyd has a history of asthma, eczema, GERD, obesity, and IBS.

Assessment: HR: 78, BP 162/92, RR 16, SpO2 96% on RA, Temp 36.9. 

Recommendation: The MD diagnoses Lloyd with stage 2 hypertension and prescribes amlodipine, a calcium channel blocker. She provides education on the DASH diet and encourages Lloyd to lose excess weight. Lloyd is scheduled for a follow-up phone appointment in two weeks for evaluation and possible dose adjustment. 

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Patient 2

Situation: Sandy, a 55-year-old female patient visits the urgent care clinic for intermittent palpitations and feelings of lightheadedness that have been occurring for the past three weeks.

Background: Sandy has a history of migraines, uterine fibroids and hyperlipidemia.

Assessment: HR: 123, BP 118/72, RR 17, SpO2 97% on RA, Temp 37.1. A 12-lead ECG is done, showing atrial fibrillation. 

Recommendation: The MD diagnoses Sandy with paroxysmal atrial fibrillation, for which she prescribes the calcium channel blocker diltiazem along with an anticoagulant. She refers Sandy to a cardiologist for further evaluation and management.

What do these two patients have in common? They were both prescribed calcium channel blockers, though for very different reasons. 

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What are calcium channel blockers? 

Calcium channel blockers (CCBs) are medications used to treat hypertension, angina, and certain tachyarrhythmias including atrial fibrillation and supraventricular tachycardia. They exert their mechanism of action in a few ways: 

  • CCBs block the influx of calcium ions into smooth muscle and cardiac cells. In smooth muscle this leads to vasodilation, and in cardiac cells this leads to decreased contractility.  
  • CCBs decrease conduction from the SA node to the AV node, which slows the heart rate.
ProblemHow a CCB helps
HypertensionVasodilation decreases peripheral vascular resistance. When PVR is decreased, blood pressure decreases as well. 
AnginaWhen PVR is decreased, the heart doesn’t have as much pressure to pump against, so it doesn’t have to work as hard. This decreases myocardial oxygen demands and reduces occurrences of angina. CCBs also cause vasodilation of coronary arteries, which reduces incidences of angina (including those caused by coronary artery spasm).
TachyarrhythmiasCCBs block the influx of calcium into excitable cardiac cells, which reduces heart rate. CCBs also slow conduction at the AV node, which also slows the heart rate. 

In the above scenarios, our patients were prescribed different CCBs. The reason for this is there are two types of calcium channel blockers: dihydropyridine and non-dihydropyridine. 

The two types of calcium channel blockers

Dihydropyridine calcium channel blockers primarily act on the blood vessels to cause vasodilation and are mainly used to treat hypertension, which is why our patient Lloyd is taking it. You will also see them used to treat stable angina and angina caused by coronary artery spasm. A commonly used dihydropyridine calcium channel blocker is amlodipine. An easy way to recognize these drugs is they end in -pine (almodipine, nefedipine, nicardipine).

Non-dihydropyridine calcium channel blockers are mainly used because of the inhibitory action they exert on myocardial cells to reduce heart rate and slow conduction at the AV node. This type of CCB is often used to treat arrhythmias such as atrial fibrillation and supraventricular tachycardia, and that’s why our patient Sandy is taking it. You may also see this type of CCB used to treat angina as well. Common CCBs of this type are diltiazem and verapamil. Unfortunately there’s no easy way to recognize them by their naming convention since they don’t have one. You’ll just need to memorize these. 

Note that though the two types are primarily used for different purposes, they still share pharmacologic characteristics. For example, even though amlodipine mainly acts as a vasodilator, it can still cause bradycardia. And, even though verapamil is often used to reduce heart rate, it does have vasodilatory properties. Keep this in mind as you consider the adverse effects of the medications. 

Now let’s take a look at how a CCB is used for angina.

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Patient 3

Situation: Randal, a 67-year-old male patient visits his primary care physician to discuss his periodic episodes of chest pain. “By the time I get to the ER, the pain has stopped, so I go home.”

Background: Randal has a history of coronary artery disease, type 2 DM, hypertension, and BPH.

Assessment: HR: 64, BP 138/72, RR 22, SpO2 98% on RA, Temp 37.2. A 12-lead ECG shows sinus rhythm with no abnormalities suggestive of current or past myocardial infarction. He tells the MD the pain occurs when he is “doing stuff around the farm” and eases up with rest.

Recommendation: The MD diagnoses Randal with stable angina and refers him to a cardiologist for further evaluation. Which type of calcium channel blocker do you think will be prescribed for Randal?

Now that you know the key differences between the two types, which one is more appropriate for Randal? Most likely, Randal will be prescribed a dihydropyridine CCB such as amlodipine because a nondihydropyridine CCB could drop his heart rate too much, and it’s already borderline at 64 beats per minute. Good job!

Nursing implications for calcium channel blockers

  • Monitor blood pressure and heart rate before and after administration
  • Watch for serious adverse reactions which can include dysrhythmias, significant bradycardia (especially with nondihydropyridine CCBs), heart block, heart failure, and Stevens-Johnson syndrome
  • Watch for reflex tachycardia, which can occur with dihydropyridine CCBs like amlodipine and nifedipine. This occurs as the heart rate compensates for vasodilation and hypotension.
  • CCB toxicity can occur, which causes profound bradycardia, hypotension, and possibly even heart block. A patient experiencing CCB toxicity will need continuous ECG monitoring, medications to increase HR and blood pressure, and possibly external pacing.
  • Key things to teach your patient include:
    • How to measure heart rate and blood pressure at home
    • To avoid grapefruit juice because it can increase the plasma concentration of CCBs, leading to toxicity
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References:

Economy, K., & Abuhamad, A. (2001). Calcium channel blockers as tocolytics. Seminars in Perinatology, 25(5), 264–271. https://www.sciencedirect.com/science/article/abs/pii/S0146000501800331

McKeever, R. G., & Hamilton, R. J. (2024). Calcium Channel Blockers. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK482473/

National Institute of Diabetes and Digestive  and Kidney Diseases. (2017). Calcium Channel Blockers. LiverTox: Clinical and Research Information on Drug Induced Liver Injury. https://pubmed.ncbi.nlm.nih.gov/31643892/

Vallerand, A. H., Sanoski, C. A., & Quiring, C. (2023). Apixaban (Eliquis). In Davis’s Drug Guide (18th ed.). F. A. Davis Company. https://www.drugguide.com/ddo/view/Davis-Drug-Guide/109824/all/apixaban?refer=true

Welsh, J. (2022, December 19). List of Every Calcium Channel Blocker. Verywell Health. https://www.verywellhealth.com/calcium-channel-blockers-for-treating-angina-1745910