Question 1

Which of the following drug categories is NOT used to treat cardiac arrhythmias?&#10;A) sodium channel blockers&#10;B) chloride channel blockers&#10;C) beta blockers&#10;D) calcium channel blockers&#10;E) drugs that prolong cardiac repolarization

Accepted Answer

Chloride channel blockers are not used to treat cardiac arrhythmias. The other drug categories listed (sodium channel blockers, beta blockers, calcium channel blockers, and drugs that prolong cardiac repolarization) are all commonly used to treat arrhythmias.

Question 2

While attempting to control one type of arrhythmia,antiarrhythmic drugs can exert &#34;proarrhythmic&#34; effects,which are indicated by&#10;A) a delay of 4 to 6 weeks before these drugs become effective&#10;B) common musculoskeletal abnormalities such as skeletal muscle fasciculations&#10;C) their ability to aggravate or initiate other cardiac rhythm abnormalities&#10;D) their ability to aggravate the proton pump in the stomach, resulting in gastric ulcers&#10;E) their ability to increase body temperature and cause fever

Accepted Answer

Proarrhythmic effects of antiarrhythmic drugs include their ability to aggravate or initiate other cardiac rhythm abnormalities. This is a serious concern as it can cause worsening of the patient's condition and even lead to life-threatening arrhythmias. The other options listed in the question are not indicative of proarrhythmic effects.

Question 3

Calcium channel blockers are useful in treating certain cardiac arrhythmias because they&#10;A) decrease the rate of discharge of the SA node&#10;B) increase conduction velocity through the AV node&#10;C) block the effects of catecholamines (epinephrine, norepinephrine) on cardiac tissues&#10;D) inhibit the ability of sodium to excite cardiac membranes&#10;E) none of the above are true; calcium channel blockers are not used to treat arrhythmias

Accepted Answer

Calcium channel blockers decrease the rate of discharge of the SA node and slow conduction through the AV node, which can help manage certain arrhythmias.

Question 4

An antiarrhythmic drug that prolongs the effective refractory period of the cardiac action potential&#10;A) will speed up repolarization of cardiac muscle cells&#10;B) will generally increase heart rate&#10;C) will decrease the time interval between cardiac action potentials&#10;D) all the above are true&#10;E) none of the above are true

Accepted Answer

Antiarrhythmic drugs that prolong the effective refractory period of the cardiac action potential do not speed up repolarization, generally increase heart rate, or decrease the time interval between cardiac action potentials. Instead, they slow down the heart rate by prolonging the period during which the heart muscle cannot be re-excited, helping to prevent arrhythmias.

Question 5

An antiarrhythmic drug used to treat bradycardia inadvertently creates tachycardia.The most likely reason is that this drug causes _____ of the ______.&#10;A) inhibition; sinoatrial node&#10;B) excitation; sinoatrial node&#10;C) inhibition; bundle of His&#10;D) excitation; bundle of His&#10;E) inhibition; atrioventricular node

Accepted Answer

An antiarrhythmic drug used to treat bradycardia would be expected to inhibit the heart rate by decreasing the rate of firing of the sinoatrial (SA) node. Therefore, if the drug inadvertently causes tachycardia, it suggests that the drug is stimulating the SA node instead of inhibiting it. Choice B correctly identifies this mechanism of action. The other options (A, C, D, and E) either do not involve the SA node or do not provide an explanation for why the drug would cause tachycardia.

Question 6

Depending on the dose and route of administration,lidocaine and similar drugs can be used as local anesthetics or cardiac antiarrhythmic drugs because these drugs affect the excitability of _____ ion channels.

A) sodium
B) potassium
C) chloride
D) calcium
E) magnesium

Accepted Answer

Lidocaine and similar drugs block sodium ion channels, which plays a role in controlling the excitability of nerves and heart muscle cells. By blocking these channels, the drug can prevent the transmission of pain signals or regulate abnormal heart rhythms. Potassium channels, chloride channels, calcium channels, and magnesium channels are not the primary targets of local anesthetics or antiarrhythmic drugs like lidocaine.

Question 7

Beta blockers are effective in treating certain cardiac arrhythmias because they _____ the excitatory effects of ______ on the heart&#10;A) increase; acetylcholine&#10;B) decrease; acetylcholine&#10;C) increase; catecholamines (epinephrine and norepinephrine)&#10;D) decrease; catecholamines (epinephrine and norepinephrine)&#10;E) increase; beta interferons

Accepted Answer

Beta blockers block the effects of catecholamines (epinephrine and norepinephrine) on the heart, thereby decreasing its excitatory effects and helping to control certain cardiac arrhythmias.

Deck 23: Treatment of Cardiac Arrhythmias