Arrhythmias Flashcards
A patient presents with a supraventricular tachycardia. The rhythm is terminated with adenosine. Which of the following correctly describes the pharmacology of adenosine?
Answer
A Beta-1 receptor agonist B Calcium channel antagonist C Potassium channel agonist D Sodium channel antagonist E Adenosine receptor agonist
E
Adenosine receptor agonist
Adenosine works by activating A1 receptors in the AV node, causing transient AV block which can terminate re-entrant arrhythmias involving the AV node.
Which of the following drugs is used to control ventricular rate in a patient presenting in atrial fibrillation with a rapid ventricular response?
Answer
A Quinidine B Digoxin C Lidocaine D Procainamide E Mexiletine
B
Digoxin
Incorrect
Digoxin acts to slow AV nodal conduction through a vagal effect. Although not effective for preventing exercise induced increases in heart rate, it does decrease resting heart rate.
The pharmacist has received a new prescription for oral amiodarone for JC. The pharmacist will counsel the patient on risks to which organs with amiodarone therapy?
Answer
A Liver, kidney, and eyes B Liver, colon, and kidney C Kidney, gall bladder, and CNS D Thyroid, pancreas, and liver E Thyroid, liver, and lungs
E
Thyroid, liver, and lungs
The commonly accepted therapeutic range for digoxin differs when used for heart failure versus atrial fibrillation. What is the therapeutic range for digoxin when used for atrial fibrillation?
Answer
A < 0.5 ng/mL B 0.5 - 0.9 ng/mL C 0.8 - 2 ng/mL D 2.5 - 3.5 ng/mL E 5 - 10 ng/mL
C
0.8 - 2 ng/mL
The therapeutic range for digoxin when used for atrial fibrillation is higher (0.8 - 2 ng/mL) than when used for heart failure (0.5 - 0.9 ng/mL).
JC is a 64 year-old male with a past medical history of NYHA Class III heart failure, dyslipidemia and hypertension. He smokes ½ pack of cigarettes daily.
Medications: Digoxin 0.25 mg daily Lasix 40 mg daily Coreg CR 20 mg daily Lovastatin 80 mg with dinner Lisinopril 40 mg daily
Physical Exam / Vitals: Height: 6’1” Weight: 199 pounds BP: 151/75 mmHg HR: 56 BPM RR: 14 BPM Temp: 98.2°F Pain: 2/10 CV: RRR Pulm: lungs clear Ext: trace edema
Labs: Na (mEq/L) = 137 (135 – 145) K (mEq/L) = 3.2 (3.5 – 5) Cl (mEq/L) = 101 (95 – 103) HCO3 (mEq/L) = 25 (24 – 30) BUN (mg/dL) = 43 (7 – 20) SCr (mg/dL) = 1.4 (0.6 – 1.3) Glucose (mg/dL) = 132 (100 – 125) Ca (mg/dL) = 8.9 (8.5 – 10.5) Mg (mEq/L) = 1.5 (1.3 – 2.1) PO4 (mg/dL) = 2.6 (2.3 – 4.7) INR = 1.1 (0 - 1.2) PT (sec) = 13 (10 - 13) aPTT (sec) = 36 (22 – 38) A1C (%) = 6.4 WBC (cells/mm3) = 6.2 (4 – 11 x 103) Hgb (g/dL) = 14.5 (13.5 – 18 male) Hct (%) = 43.4 (38 – 50 male) Plt (cells/mm3) = 342 (150 – 450 x 103) AST (IU/L) = 54 (10 – 40) ALT (IU/L) = 49 (10 – 40) Digoxin (ng/mL) = 0.9 (indication specific) Albumin (g/dL) = 3.5 (3.5 – 5)
Question
The pharmacist has received a new prescription for oral amiodarone for JC. Before the prescription is filled, the pharmacist should call the prescriber to recommend the following medication change/s: (Select ALL that apply.)
Answer
A Decrease dose of lovastatin. B Discontinue lisinopril. C Increase dose of digoxin. D Decrease dose of digoxin. E Increase dose of Lasix. Incorrect
A Decrease dose of lovastatin. D Decrease dose of digoxin. Amiodarone is an inhibitor of CYP 2C9, 2D6, 3A4 and p-glycoprotein. When starting amiodarone, the dose of digoxin must be decreased by 30-50%. Lovastatin (Mevacor) should not exceed a maximum daily dose of 40 mg in patients on amiodarone.
What is the goal resting heart rate in patients with symptomatic atrial fibrillation?
Answer
A HR < 150 BPM B HR < 110 BPM C HR < 100 BPM D HR < 80 BPM E HR < 60 BPM
D
HR < 80 BPM
In patients with symptomatic atrial fibrillation, heart rate should be maintained at < 80 BPM. A higher goal may be appropriate (< 110 BPM) in asymptomatic patients with preserved EF.
A prescriber calls to speak to a pharmacist. A positive antinuclear antibody (ANA) was reported on his patient’s labs. The pharmacist realizes that several drugs can cause this. Which antiarrhythmic drug carries a boxed warning regarding this?
Answer
A Sotalol B Propafenone C Amiodarone D Dofetilide E Procainamide
E
Procainamide
Procainamide is notable for causing drug-induced lupus erythematosus (DILE) in up to 20-30% of patients who use it long-term. A positive antinuclear antibody (ANA), though generally nonspecific, points toward SLE or DILE.
JC has been using amiodarone for nine months. Long-term therapy with amiodarone can cause the following thyroid problems: (Select ALL that apply.)
Answer
A
Hypothyroidism, as demonstrated by a high TSH and low FT4
B
Hypothyroidism, as demonstrated by a low TSH and high FT4
C
Hyperthyroidism, as demonstrated by a low TSH and high FT4
D
Hyperthyroidism, as demonstrated by a high TSH and low FT4
E
Amiodarone does not affect the thyroid
A
Hypothyroidism, as demonstrated by a high TSH and low FT4
C
Hyperthyroidism, as demonstrated by a low TSH and high FT4
Amiodarone-induced thyroid dysfunction occurs in about 4% of patients. The effects range from abnormal thyroid function test findings to overt hyperthyroidism or hypothyroidism. All patients taking amiodarone should be monitored for symptoms that could indicate thyroid dysfunction and have thyroid function monitored with labs (FT4 and TSH) on a regular basis. Refer to the Thyroid Disorders chapter for interpretation TSH and FT4.
The pharmacist overhears the cardiologist saying that a “rate control strategy” will be used for a patient. Which group of medications is most appropriate for a patient being treated with a rate control strategy?
Answer
A Dofetilide + aspirin B Digoxin + flecainide C Diltiazem + clopidogrel D Propafenone + warfarin E Metoprolol + apixaban
E
Metoprolol + apixaban
When treating atrial fibrilation, a decision must be made between a rate and rhythm control strategy. With the rate control strategy, the patient remains in atrial fibrillation with a rate controlling medication(s) and stroke prophylaxis (with aspirin or anticoagulation) based on CHADS2 score (refer to the Anticoagulation chapter). Clopidogrel (and other P2Y12 inhibitors) are not appropriate by themselves for stroke prophylaxis. P2Y12 inhibitors can be used with aspirin in a patient who does not tolerate oral anticoagulation, but this is not common.
MJ is a 52 year old male with paroxysmal atrial fibrillation, hypertension and dyslipidemia.
Medications: Hydrochlorothiazide 12.5 mg daily Norvasc 10 mg daily Quinidine gluconate 324 mg Q12H Xarelto 20 mg with dinner Lipitor 10 mg daily
Question:
The patient calls his pharmacist because he read online about cinchonism caused by quinidine. The pharmacist can reassure the patient that cinchonism is usually reversible if the drug is stopped and by counseling him to watch for the following signs/symptoms of cinchonism:
Answer
A
Ringing in the ears, blurred vision, confusion
B
Dry mouth, constipation and urinary retention
C
Confusion, tremor and dyspnea
D
Loss of smell, gingival hyperplasia and headache
E
Blurred vision, blue skin discoloration and insomnia
A
Ringing in the ears, blurred vision, confusion
Correct
Quinidine comes from the bark of the cinchona tree. Cinchonism is a well-known (and frequently tested) side effect of quinidine, though this antiarrhythmic is rarely used in contemporary practice. Common complaints in cinchonism include tinnitus (ringing in the ears), headache, confusion and blurred vision.
Which of the following statements regarding amiodarone is correct?
Answer
A
Long intravenous infusions should be administered in glass or polyolefin containers.
B
Amiodarone is available only as an intravenous injection.
C
Amiodarone is administered four times per day when treating arrhythmias.
D
Unlike other antiarrhythmic drugs, amiodarone is not proarrhythmic.
E
Patients taking amiodarone should be monitored for tachycardia and hypertension.
A
Long intravenous infusions should be administered in glass or polyolefin containers.
Amiodarone infusions longer than 2 hours must be aministered in non-PVC containers. When administered orally, it is generally given once or twice daily (which makes sense based on its half-life). Bradycardia and hypotension are expected side effects due to beta blocking properties of amiodarone.
CAST is a landmark arrhythmia trial. Patients were randomized to use of certain antiarrhythmic drugs vs placebo to suppress PVCs after MI. Which antiarrhythmic was associated with increased mortality in CAST?
Answer
A Amiodarone B Flecainide C Ibutilide D Quinidine E Mexiletine
B
Flecainide
Two Class Ic antiarrhythmics, flecainide and encainide (now discontinued), were studied in CAST and associated with increased mortality. Today all Class I antiarrhythmics carry a boxed warning about increased mortality in this specific population (non-life threatening ventricular arrhythmias in post-MI patients). Flecainide is still recommended for certain patients in guidelines for atrial fibrillation. CAST did not involve patients with atrial arrhythmias.
Which of the following are well-established side effects of amiodarone therapy? (Select ALL that apply.)
Answer
A Hemolytic anemia B Taste perversions C Hypothyroidism D Microdeposits in the cornea E Photosensitivity
C Hypothyroidism D Microdeposits in the cornea E Photosensitivity
Hypothyroidism, corneal microdeposits and photosensitivity are well-established side effects of amiodarone. Other common side effects include nausea, dizziness, hypotension and bradycardia.
Lopressor acts as an antiarrhythmic by blocking which of the following ion channels in the SA and AV nodes?
Answer
A Sodium B Potassium C Calcium D Chloride E Magnesium
C
Calcium
Beta blockers and calcium channel blockers act as antiarrhythmics by blocking calcium channels in the SA and AV nodes.
The primary pathway of metabolism of procainamide is:
Answer
A Oxidation B Esterification C Glucuronidation D Acetylation E Sulfation
D
Acetylation
Procainamide is metabolized in the liver by acetylation to N-acetylprocainamide (NAPA), an active metabolite. Both compounds contribute to the efficacy of the drug as an antiarrhythmic. Due to ethnic and individual differences in acetylation status, the ratio of procainamide and NAPA is different in each patient.
