Question 1

Which phase of the cardiac action potential is characterised by the opening of the sodium channel activation gate?&#10;A) Phase 0&#10;B) Phase 1&#10;C) Phase 2&#10;D) Phase 3

Accepted Answer

Phase 0 of the cardiac action potential is characterised by the rapid depolarisation of the membrane due to the opening of voltage-gated sodium channels. This is facilitated by the activation gate of the sodium channels opening, allowing sodium ions to rapidly influx into the cell.

Question 2

Atropine is especially useful in what sort of dysrhythmia?&#10;A)Tachycardia&#10;B)Bradycardia&#10;C)Pre-ventricular contraction&#10;D)AV conduction block

Accepted Answer

Atropine is particularly useful in treating bradycardia. It works by blocking the parasympathetic input of the vagus nerve to the sinoatrial (SA) node, increasing the heart rate. It is not effective in treating other dysrhythmias such as tachycardia, pre-ventricular contraction, or AV conduction block.

Question 3

Which electrolyte is not responsible for maintaining a normal heart rhythm?&#10;A)Calcium&#10;B)Potassium&#10;C)Sodium&#10;D)Magnesium

Accepted Answer

Magnesium

Question 4

Class II antidysrhythmic drugs are also known as what?&#10;A)Calcium channel blockers&#10;B)ACE inhibiters&#10;C)Beta blockers&#10;D)Adrenergic agonists

Accepted Answer

Class II antidysrhythmic drugs are beta blockers, which work by blocking the effects of adrenaline on the heart, thereby slowing down the heart rate and reducing the risk of arrhythmias. Calcium channel blockers (A) work by blocking calcium channels, which reduces the force of contractions in the heart muscle, while ACE inhibitors (B) work by dilating blood vessels and reducing blood pressure. Adrenergic agonists (D) activate the sympathetic nervous system and can increase heart rate and blood pressure, which may exacerbate arrhythmias.

Question 5

Which is an example of a prodysrhythmic agent?&#10;A)Fexofenadine&#10;B)Clarithromycin&#10;C)Haloperidol&#10;D)All of the above

Accepted Answer

All of the above options, Fexofenadine, Clarithromycin, and Haloperidol, can act as prodysrhythmic agents, meaning they have the potential to cause or worsen cardiac arrhythmias.

Question 6

Which one of the following mechanisms describes the general action of antidysrhythmic agents?&#10;A) Impeding the movement of ions across cardiac cell membranes&#10;B) Enhancing cardiac automaticity&#10;C) Shortening the cardiac action potential&#10;D) Enhancing impulse conduction in the heart

Accepted Answer

Antidysrhythmic agents typically work by impeding the movement of ions across cardiac cell membranes, which can help to stabilize the heart's electrical activity and prevent arrhythmias. This can involve various mechanisms, such as blocking ion channels, altering ion concentrations, or affecting ion exchange pumps. Enhancing cardiac automaticity (B) or impulse conduction (D) could actually increase the risk of arrhythmias, while shortening the cardiac action potential (C) might not be effective for all types of arrhythmias.

Question 7

Verapamil is a class IV antidysrhythmic agent.Verapamil belongs to what class of drug?&#10;A)Calcium channel blockers&#10;B)ACE inhibitors&#10;C)&#946;-blockers&#10;D)Inotropic agents

Accepted Answer

Verapamil is a calcium channel blocker, which is a type of drug that blocks the influx of calcium ions into cardiac and smooth muscle cells. This decreases the force of contraction of the heart and relaxes smooth muscle, making it useful in treating hypertension, angina, and certain types of dysrhythmias.

Question 8

Which drug listed below is an example of a class III antidysrhythmic?&#10;A)Dopamine&#10;B)Amiodarone&#10;C)Dobutamine&#10;D)Atropine

Accepted Answer

Amiodarone is a class III antidysrhythmic medication commonly used to treat ventricular and supraventricular arrhythmias. Choice A, dopamine, is a medication used to treat hypotension and shock. Choice C, dobutamine, is a medication used to treat heart failure. Choice D, atropine, is a medication used to treat bradycardia and as a preoperative medication.

Question 9

Which of the following are mechanisms of action of the class I antidysrhythmics?&#10;A)They have local anaesthesia properties.&#10;B)They have a high affinity for blocking active sodium channels.&#10;C)They affect phase four of the action potential.&#10;D)All of the above.

Accepted Answer

Class I antidysrhythmics have all of the mentioned mechanisms of action. They have local anaesthesia properties, high affinity for blocking active sodium channels, and affect phase four of the action potential.

Deck 50: Medicines Used to Treat Cardiac Dysrhythmia