Which of the following medications does the nurse identify as a calcium channel blocker used to treat tachycardia and manage heart rate?

Choice A rationale:

Dopamine was once considered a first-line vasopressor for cardiogenic shock. However, recent studies have shown that it is associated with increased mortality compared to norepinephrine.

Dopamine has dose-dependent effects on dopamine receptors, beta receptors, and alpha receptors. At low doses (1-5 mcg/kg/min), it primarily stimulates dopamine receptors, leading to renal vasodilation and increased urine output. At moderate doses (5-10 mcg/kg/min), it stimulates beta receptors, resulting in increased heart rate and contractility. At high doses (>10 mcg/kg/min), it stimulates alpha receptors, causing vasoconstriction.

The main concern with dopamine is its potential to cause arrhythmias, particularly at higher doses. This is due to its effects on beta receptors, which can increase heart rate and myocardial oxygen demand.

Additionally, dopamine can cause tachyphylaxis, meaning that its effects can diminish over time, requiring higher doses to achieve the same effect.

Choice B rationale:

Norepinephrine is a potent alpha-adrenergic agonist that causes vasoconstriction, leading to an increase in blood pressure. It has minimal effects on beta receptors, so it is less likely to cause tachycardia and arrhythmias compared to dopamine.

Norepinephrine also has some inotropic effects, meaning that it can increase the strength of contraction of the heart muscle.

Studies have shown that norepinephrine is associated with improved survival rates in patients with cardiogenic shock compared to dopamine.

It is generally well-tolerated, with the most common side effects being hypertension and peripheral vasoconstriction.

Choice C rationale:

Epinephrine is a potent alpha- and beta-adrenergic agonist that causes vasoconstriction, increased heart rate, and increased contractility.

It is typically used as a second-line agent in cardiogenic shock, after norepinephrine has failed to achieve adequate blood pressure.

Epinephrine can cause significant tachycardia and arrhythmias, so it should be used with caution in patients with underlying heart disease.

Choice D rationale:

Vasopressin is a hormone that causes vasoconstriction by acting on V1 receptors in vascular smooth muscle. It is sometimes used as an adjunct to norepinephrine in patients with refractory cardiogenic shock.

Vasopressin has the potential to cause coronary vasoconstriction, so it should be used with caution in patients with coronary artery disease.

Choice A rationale:

Sildenafil (Viagra) is a phosphodiesterase-5 (PDE-5) inhibitor that is primarily used to treat erectile dysfunction. However, it also has vasodilatory effects, meaning it widens blood vessels. This can lead to a significant drop in blood pressure, especially when combined with nitroglycerin, another potent vasodilator.

Nitroglycerin is commonly used to treat chest pain (angina) and heart failure. It works by relaxing the smooth muscles in blood vessels, which allows them to widen and increase blood flow to the heart. This can help to relieve chest pain and improve heart function.

When sildenafil and nitroglycerin are taken together, their combined vasodilatory effects can cause a severe drop in blood pressure, known as hypotension. This can lead to a number of serious complications, including: dizziness, lightheadedness, fainting, heart attack, stroke.

The risk of hypotension is particularly high in patients who are already taking other medications that can lower blood pressure, such as alpha-blockers or nitrates. It is also important to note that the effects of sildenafil can last for up to 24-48 hours, so it is important to avoid taking nitroglycerin within this timeframe.

Due to the significant risk of hypotension, it is generally recommended that sildenafil be avoided within 24-48 hours of nitroglycerin administration.

Rationales for other choices:

Choice B: Aspirin

Aspirin is an antiplatelet medication that is often used to prevent blood clots. It does not have significant vasodilatory effects and does not interact with nitroglycerin in a way that would contraindicate its use.

Choice C: Adenosine

Adenosine is a medication that is used to treat certain types of arrhythmias (irregular heartbeats). It can cause a brief drop in blood pressure, but this effect is usually mild and transient. Adenosine does not interact with nitroglycerin in a way that would contraindicate its use.

Choice D: Oxygen

Oxygen is a gas that is often used to treat patients with respiratory problems. It does not have any direct vasodilatory effects and does not interact with nitroglycerin.