A nurse is caring for a client admitted to the intensive care unit for a cardiac dysrhythmia. The nurse understands the prescribed calcium channel blocker has which of the following mechanisms of action?
Acts on the beta cells within the heart and lungs to regulate cardiac rhythm
Increases heart rate and increases myocardial contractility
Reduces the contractility and conductivity of the heart
Increase oxygen to the systemic circulation
The Correct Answer is C
A) "Acts on the beta cells within the heart and lungs to regulate cardiac rhythm.": This statement is incorrect because calcium channel blockers do not primarily act on beta cells. Instead, they block calcium channels in cardiac and smooth muscle, which affects heart contractility and conductivity.
B) "Increases heart rate and increases myocardial contractility.": Calcium channel blockers typically do the opposite; they decrease heart rate and myocardial contractility by inhibiting calcium entry into the heart muscle cells. Therefore, this statement does not accurately describe their mechanism of action.
C) "Reduces the contractility and conductivity of the heart.": This statement accurately reflects the action of calcium channel blockers. By blocking calcium entry, these medications decrease myocardial contractility and slow down electrical conduction through the heart, which can help manage dysrhythmias.
D) "Increase oxygen to the systemic circulation.": While calcium channel blockers can improve blood flow and reduce myocardial oxygen demand by decreasing heart workload, their primary action does not directly focus on increasing oxygen delivery to systemic circulation. Their primary role is in managing heart contractility and rhythm.
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Correct Answer is A
Explanation
A) Gallstones: Gemfibrozil is associated with an increased risk of gallstones. This medication can alter the metabolism of lipids and bile, potentially leading to the formation of gallstones. Clients should be monitored for symptoms such as abdominal pain or discomfort that could indicate gallbladder issues.
B) Decreased PT time: Gemfibrozil does not typically affect prothrombin time (PT). Instead, it may interact with anticoagulants and potentially increase PT time, requiring careful monitoring in patients taking both medications.
C) Hyperkalemia: While hyperkalemia can occur with certain lipid-lowering medications, it is not a common side effect associated with gemfibrozil. This drug primarily affects triglycerides and cholesterol levels without significantly impacting potassium levels.
D) Increased creatinine clearance: Gemfibrozil is not known to increase creatinine clearance; in fact, it can sometimes affect renal function. Monitoring kidney function is important, but increased creatinine clearance is not an expected outcome with this medication.
Correct Answer is D
Explanation
A) Atenolol: This is a beta-blocker that can be used for various cardiac conditions, including hypertension and certain arrhythmias, but it is not typically the first-line treatment for acute life-threatening ventricular dysrhythmias in the emergency setting.
B) Lisinopril: This medication is an ACE inhibitor primarily used to manage hypertension and heart failure. It does not address acute ventricular dysrhythmias and would not be appropriate for immediate use in this scenario.
C) Adenosine: While adenosine is effective for certain types of supraventricular tachycardia, it is not indicated for life-threatening ventricular dysrhythmias. It has a very short duration of action and is not the drug of choice in this context.
D) Procainamide: This antiarrhythmic medication is specifically used to treat life-threatening ventricular dysrhythmias. It works by stabilizing the cardiac membrane and is indicated in emergency situations to manage these types of arrhythmias. Therefore, preparing procainamide is the most appropriate action for the nurse in this scenario.