Home Books Katzung & Trevor's Pharmacology: Examination & Board Review, 12e

Chapter 13: Drugs Used in Heart Failure

A 73-year-old man with an inadequate response to other drugs is to receive digoxin for chronic heart failure. He is in normal sinus rhythm with a heart rate of 88 and blood pressure of 135/85 mm Hg. Which of the following is the best-documented mechanism of beneficial action of cardiac glycosides?

(A) A decrease in calcium uptake by the sarcoplasmic reticulum

(B) An increase in a late transmembrane sodium current

(C) A modification of the actin molecule

(D) An increase in systolic cytoplasmic calcium levels

(E) A block of cardiac β adrenoceptors

Digitalis does not decrease calcium uptake by the sarcoplasmic reticulum or increase sodium current; it does not modify actin. Cardiac adrenoceptors are not affected. The most accurate description of digitalis’s mechanism in this list is that it increases systolic cytoplasmic calcium by inhibiting Na⁺/K⁺ transport by the ATPase sodium pump and indirectly altering Na⁺/Ca²⁺ exchange. The answer is D.

A 73-year-old man with an inadequate response to other drugs is to receive digoxin for chronic heart failure. He is in normal sinus rhythm with a heart rate of 88 and blood pressure of 135/85 mm Hg. After your patient has been receiving digoxin for 3 weeks, he presents to the emergency department with an arrhythmia. Which one of the following is most likely to contribute to the arrhythmogenic effect of digoxin?

(A) Increased parasympathetic discharge

(B) Increased intracellular calcium

(C) Decreased sympathetic discharge

(D) Decreased intracellular ATP

(E) Increased extracellular potassium

The effects of digitalis include increased vagal action on the heart (not arrhythmogenic) and increased intracellular calcium, including calcium overload, the most important cause of toxicity. Decreased sympathetic discharge and increased extracellular potassium and magnesium reduce digitalis arrhythmogenesis. The answer is B.

A patient who has been taking digoxin for several years for atrial fibrillation and chronic heart failure is about to receive atropine for another condition. A common effect of digoxin (at therapeutic blood levels) that can be almost entirely blocked by atropine is

(A) Decreased appetite

(B) Headaches

(C) Increased atrial contractility

(D) Increased PR interval on ECG

(E) Tachycardia

The parasympathomimetic effects of digitalis can be blocked by muscarinic blockers such as atropine. The only parasympathomimetic effect in the list provided is increased PR interval, a manifestation of slowed AV conduction. The answer is D

A 65-year-old woman has been admitted to the coronary care unit with a left ventricular myocardial infarction. She develops acute severe heart failure with marked pulmonary edema, but no evidence of peripheral edema. Which one of the following drugs would be most useful?

(A) Digoxin

(B) Furosemide

(C) Minoxidil

(D) Propranolol

(E) Spironolactone

Acute severe congestive failure with pulmonary edema often requires a vasodilator that reduces intravascular pressures in the lungs. Furosemide has such vasodilating actions in the context of acute failure in addition to its diuretic effect. Pulmonary edema also involves a shift of fluid from the intravascular compartment to the lungs. Minoxidil would decrease arterial pressure and increase the heart rate excessively. Digoxin has a slow onset of action and lacks vasodilating effects. Spironolactone is useful in chronic failure but not in acute pulmonary edema. Pulmonary vasodilation and removal of edema fluid by diuresis are accomplished by furosemide. The answer is B.

A 72-year-old woman has long-standing heart failure. Which one of the following drugs has been shown to reduce mortality in chronic heart failure?

(A) Atenolol

(B) Digoxin

(C) Furosemide

(D) Nitroprusside

(E) Spironolactone

Of the drugs listed, only spironolactone has been shown to reduce mortality in this highly lethal disease. Digoxin, furosemide, and nitroprusside are used in the management of symptoms. The answer is E.

Which of the following drugs increases the plasma levels of endogenous BNP and also blocks angiotensin receptors?

(A) Furosemide

(B) Losartan

(C) Nesiritide

(D) Sacubitril

(E) Spironolactone

Furosemide has no significant effect on peptide metabolism and does not block AT₁ receptors. Losartan blocks AT₁ receptors but has no effect on peptide metabolism. Nesiritide is a synthetic BNP and does not block AT₁ receptors. Spironolactone blocks the aldosterone receptor in the kidney. Only sacubitril/valsartan has the combined effect listed in the stem of this question. The answer is D.

Which one of the following drugs is associated with clinically useful or physiologically important positive inotropic effect?

(A) Captopril

(B) Dobutamine

(C) Enalapril

(D) Losartan

(E) Nesiritide

Although they are extremely useful in heart failure, ACE inhibitors (eg, captopril, enalapril), and angiotensin receptor blockers (ARBs, eg, losartan) have no positive inotropic effect on the heart. Nesiritide is a vasodilator with diuretic effects and renal toxicity. Dobutamine is a β₁-selective adrenoceptor agonist. The answer is B.

A 68-year-old man with a history of chronic heart failure goes on vacation and abandons his low-salt diet. Three days later, he develops severe shortness of breath and is admitted to the local hospital emergency department with significant pulmonary edema. The first-line drug of choice in most cases of acute decompensation in patients with chronic heart failure is

(A) Atenolol

(B) Captopril

(C) Carvedilol

(D) Digoxin

(E) Diltiazem

(F) Dobutamine

(G) Enalapril

(H) Furosemide

(I) Metoprolol

(J) Spironolactone

In both acute and chronic failure and systolic (HFrEF) and diastolic heart failure (HFpEF), the initial treatment of choice is usually furosemide. The answer is H

Which of the following has been shown to prolong life in patients with chronic congestive failure in spite of having a negative inotropic effect on cardiac contractility?

(A) Carvedilol

(B) Digoxin

(C) Dobutamine

(D) Enalapril

(E) Furosemide

Several β blockers, including carvedilol, have been shown to prolong life in heart failure patients even though these drugs may have a negative inotropic action on the heart. Their benefits presumably result from some other β-mediated effect, and at least one other β blocker has failed to show a mortality benefit. The answer is A.

A 5-year-old child was vomiting and was brought to the emergency department with sinus arrest and a ventricular rate of 35 bpm. An empty bottle of his uncle’s digoxin was found where he was playing. Which of the following is the drug of choice in treating a severe overdose of digoxin?

(A) Digoxin antibodies

(B) Lidocaine infusion

(C) Magnesium infusion

(D) Phenytoin by mouth

(E) Potassium by mouth

The drug of choice in severe, massive overdose with any cardiac glycoside is digoxin antibody, Digibind. The other drugs listed are used in moderate overdosage associated with increased automaticity. The answer is A.

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Chapter 13: Drugs Used in Heart Failure

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