Which one of the following drugs predictably prolongs the PR interval and increases cardiac contractility?

Correct Answer: A

Rationale: In this question, the correct answer is A) Digoxin. Digoxin is a cardiac glycoside that acts by inhibiting the sodium-potassium pump, leading to an increase in intracellular calcium levels. This increase in calcium enhances cardiac contractility, making the heart muscle more efficient at pumping blood. Digoxin also predictably prolongs the PR interval by slowing down the conduction of electrical impulses through the atrioventricular (AV) node. This effect is important to note as it can be seen on an electrocardiogram (ECG) when monitoring patients on digoxin therapy. Now, let's discuss why the other options are incorrect: - B) Lidocaine is a local anesthetic and antiarrhythmic drug that primarily works by blocking sodium channels in the heart to prevent abnormal electrical activity. It does not affect the PR interval or increase cardiac contractility. - C) Propranolol is a beta-blocker that decreases heart rate and blood pressure by blocking beta-adrenergic receptors. It does not predictably prolong the PR interval or increase cardiac contractility. - D) Quinidine is an antiarrhythmic medication that works by blocking sodium and potassium channels in the heart. While it can prolong the QT interval on an ECG, it does not specifically prolong the PR interval or increase cardiac contractility like digoxin. In an educational context, understanding the effects of different cardiovascular drugs on the heart's electrical conduction system and contractility is crucial for healthcare professionals, especially those working in cardiology or critical care settings. Recognizing the unique actions of each medication helps in making informed decisions regarding treatment options and monitoring for potential side effects or complications.

Correct Answer: B

Rationale: In the context of cardiovascular drugs, the correct answer to the question is B) Depression of cardiac contractility. Quinidine is a class I antiarrhythmic drug that primarily works by blocking sodium channels in cardiac myocytes. The depression of cardiac contractility is not a desirable effect clinically because it can lead to a decrease in cardiac output and exacerbate heart failure in patients with compromised cardiac function. Option A) Shortening of A-V nodal refractory period due to vagolytic action is a useful property of quinidine as it can help in managing certain types of arrhythmias by affecting the conduction of electrical impulses in the heart. Option C) Decrease in the automaticity of the normal pacemaker is also a desirable effect of quinidine as it helps in reducing abnormal electrical activity in the heart and can be beneficial in treating arrhythmias. Option D) Reduction in the slope of slow diastolic depolarization is another useful property of quinidine as it can help in stabilizing the heart's electrical activity and preventing the occurrence of certain types of arrhythmias. From an educational perspective, understanding the pharmacological properties of cardiovascular drugs like quinidine is crucial for healthcare professionals involved in the management of cardiac conditions. Knowing the desired effects as well as the potential adverse effects of these drugs is essential for safe and effective patient care. This knowledge helps in making informed decisions regarding drug selection, dosing, monitoring, and managing potential drug interactions or adverse effects.

Correct Answer: B

Rationale: In this question, the correct answer is B) Beta blocker. Class II anti-arrhythmic agents, such as beta blockers, work by blocking beta-adrenergic receptors in the heart, leading to a decrease in heart rate and contractility. This effect helps in managing arrhythmias by stabilizing the heart's electrical activity. Option A) Calcium channel blocker primarily works by blocking calcium channels, affecting the heart's contractility and conductivity. While calcium channel blockers are used in various cardiovascular conditions, they do not belong to Class II anti-arrhythmic agents. Option C) Sodium channel blocker, like Class I anti-arrhythmic agents, work by blocking sodium channels in the heart, affecting the depolarization phase of cardiac action potentials. This class is different from Class II agents. Option D) ACE inhibitor is not an anti-arrhythmic agent. ACE inhibitors work by inhibiting the conversion of angiotensin I to angiotensin II, primarily used in conditions like hypertension and heart failure. Understanding the classification and mechanisms of action of different cardiovascular drugs is crucial for healthcare professionals to make informed decisions in managing patients with cardiac conditions. Identifying the correct Class II anti-arrhythmic agents, such as beta blockers, ensures appropriate treatment selection and optimal patient outcomes.

Correct Answer: C

Rationale: Gemfibrozil is a fibric acid derivative used to lower cholesterol and triglyceride levels in the blood. The correct answer is C) Active gallbladder disease. Gemfibrozil can increase the risk of gallstones and aggravate existing gallbladder conditions. Educating the client about this contraindication is crucial to prevent complications. Option A) History of MI is incorrect because gemfibrozil can actually benefit individuals with a history of MI by reducing their risk of cardiovascular events. Option B) History of elevated triglyceride levels is incorrect because this is the very condition gemfibrozil is used to treat. Option D) Taking aspirin with gemfibrozil is incorrect because there are no known significant interactions between these two medications. In an educational context, it's important for nurses to understand the contraindications of medications to provide safe and effective care to their patients. By explaining the rationale behind the correct answer and why the other options are incorrect, nurses can better guide patients in their medication management and promote positive health outcomes.

Correct Answer: C

Rationale: In this scenario, the correct answer is C) Hypotension. Nitrous oxide is known to have vasodilatory effects, leading to a decrease in systemic vascular resistance and subsequently causing hypotension. This effect is particularly important to monitor in patients undergoing dental procedures where nitrous oxide is used as an anesthetic agent. Option A) Airway resistance increases apically is incorrect. Nitrous oxide is actually a bronchodilator, making this option inaccurate. Option B) Bronchodilation is also incorrect as nitrous oxide, being a smooth muscle relaxant, leads to bronchodilation rather than bronchoconstriction. Option D) Redirection of blood flow to the heart is incorrect. While nitrous oxide may affect blood flow dynamics, it does not specifically redirect blood flow to the heart. Educationally, understanding the physiological effects of nitrous oxide is crucial for healthcare providers, especially in scenarios like dental procedures. Knowing that nitrous oxide can induce hypotension informs providers to monitor patients closely and be prepared to manage any hemodynamic changes that may occur during or after the procedure.