Mechanism and Pharmacological Effects of Quinidine
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Questions and Answers

What is the primary mechanism of action of Quinidine related to Na+ channels?

  • It blocks activated Na+ channels. (correct)
  • It opens voltage-gated Na+ channels.
  • It increases the permeability of Na+ channels.
  • It enhances Na+ channel activation.

    • What occurs at low doses of Quinidine regarding AV conduction?

  • It has no effect on AV conduction.
  • It blocks conduction through the AV node completely.
  • It decreases AV conduction.
  • Its vagolytic action predominates, increasing AV conduction. (correct)

    • What is one of the pharmacological effects of Quinidine related to the heart?

  • It increases heart rate significantly.
  • It has a negative inotropic effect. (correct)
  • It stabilizes heart rate during arrhythmias.
  • It has a positive inotropic effect.

    • How does Quinidine affect the autonomic nervous system?

    <p>It blocks muscarinic and α receptors.</p> Signup and view all the answers

    What is the effect of Quinidine on action potential duration (APD)?

    <p>It increases action potential duration.</p> Signup and view all the answers

    What is the result of Quinidine's complex effects on AV conduction at therapeutic doses?

    <p>Its direct action predominates, decreasing AV conduction.</p> Signup and view all the answers

    What is the primary reason quinidine is rarely used today?

    <p>More effective and less toxic alternatives are available.</p> Signup and view all the answers

    Which of the following is NOT an adverse effect associated with quinidine?

    <p>Severe rash</p> Signup and view all the answers

    What can occur as a result of rapid intravenous infusion of quinidine?

    <p>Hypotension due to alpha-receptor blockade.</p> Signup and view all the answers

    Which statement best describes the mechanism that leads to paradoxical tachycardia in patients taking quinidine?

    <p>Quinidine has an atropine-like action that increases conduction.</p> Signup and view all the answers

    Which arrhythmias was quinidine historically used to treat?

    <p>Supraventricular and ventricular arrhythmias.</p> Signup and view all the answers

    Which of the following symptoms is directly associated with cinchonism from quinidine use?

    <p>Tinnitus</p> Signup and view all the answers

    What describes the implications of quinidine's atropine-like action?

    <p>It may lead to increased conduction and potentially tachycardia.</p> Signup and view all the answers

    When was quinidine primarily used in clinical practices?

    <p>Traditionally for various arrhythmias before better drugs were available.</p> Signup and view all the answers

    What action does amiodarone primarily block to affect the cardiac action potential?

    <p>K+ channels</p> Signup and view all the answers

    Which of the following arrhythmias is NOT typically treated with amiodarone?

    <p>Bradycardia</p> Signup and view all the answers

    What percentage of iodine does amiodarone contain?

    <p>40%</p> Signup and view all the answers

    What is a significant side effect of amiodarone due to its tissue accumulation?

    <p>Pulmonary toxicity</p> Signup and view all the answers

    Dronedarone differs from amiodarone in that it does not contain which element?

    <p>Iodine</p> Signup and view all the answers

    In terms of pharmacology, which mechanism does amiodarone NOT utilize?

    <p>Increasing excitability</p> Signup and view all the answers

    How does amiodarone affect the effective refractory period (ERP) of the cardiac action potential?

    <p>Increases ERP</p> Signup and view all the answers

    Which mechanism is primarily responsible for the negative inotropic effect of amiodarone?

    <p>Blockade of Ca2+ channels</p> Signup and view all the answers

    What is the mechanism of action of adenosine in the AV conducting system?

    <p>Opening of K+ channels and inhibition of Ca2+ channels</p> Signup and view all the answers

    What is the recommended bolus dose of adenosine for immediate termination of paroxysmal supraventricular tachycardia?

    <p>6 mg i.v.</p> Signup and view all the answers

    In which of the following conditions is adenosine contraindicated?

    <p>Asthma</p> Signup and view all the answers

    What effect does caffeine have on the efficacy of adenosine?

    <p>It decreases the effectiveness of adenosine.</p> Signup and view all the answers

    What is the primary indication for the use of direct current cardioversion?

    <p>For emergency control of any type of arrhythmia</p> Signup and view all the answers

    What is the half-life of adenosine?

    <p>8-10 seconds</p> Signup and view all the answers

    Which side effect is associated with the rapid administration of adenosine?

    <p>Bronchospasm</p> Signup and view all the answers

    How does direct current cardioversion function?

    <p>It applies electric shock to restore normal heart rhythm.</p> Signup and view all the answers

    What is the recommended duration of anticoagulation following electrical cardioversion?

    <p>4 weeks</p> Signup and view all the answers

    What is the primary purpose of laser ablation in treating arrhythmias?

    <p>To eliminate abnormal electrical pathways</p> Signup and view all the answers

    Which of the following statements about artificial pacemakers is true?

    <p>They are battery-powered devices implanted under the skin.</p> Signup and view all the answers

    What is the definitive treatment for Wolff-Parkinson-White (WPW) syndrome?

    <p>Catheter ablation</p> Signup and view all the answers

    Which aspect is critical before performing a procedure that involves heparin?

    <p>Ensuring the patient is heparinized</p> Signup and view all the answers

    What mechanism is employed during laser ablation to correct arrhythmias?

    <p>Delivering energy to targeted heart muscle areas</p> Signup and view all the answers

    Quinidine has a positive inotropic effect on cardiac muscle.

    <p>False</p> Signup and view all the answers

    Quinidine exhibits an atropine-like action by blocking muscarinic and α receptors, resulting in vagolytic effects.

    <p>True</p> Signup and view all the answers

    At therapeutic doses, quinidine tends to increase AV conduction.

    <p>False</p> Signup and view all the answers

    Quinidine primarily acts on K+ channels to prolong the action potential duration (APD).

    <p>False</p> Signup and view all the answers

    The effects of quinidine on action potential duration (APD) and effective refractory period (ERP) result in a decrease in excitability.

    <p>True</p> Signup and view all the answers

    Quinidine is considered a first-line treatment for all types of tachycardia currently.

    <p>False</p> Signup and view all the answers

    Digitalis or verrapamil should be administered after quinidine to improve AV conduction.

    <p>False</p> Signup and view all the answers

    Quinidine has no effect on the QT interval and does not predispose patients to torsades de pointes.

    <p>False</p> Signup and view all the answers

    Procainamide is equivalent to quinidine as an antiarrhythmic agent and has similar toxic effects.

    <p>True</p> Signup and view all the answers

    Long-term therapy with procainamide can lead to drug-induced systemic lupus erythematosus in all patients.

    <p>False</p> Signup and view all the answers

    Quinidine is commonly prescribed today due to its effective rate control and minimal side effects.

    <p>False</p> Signup and view all the answers

    Procainamide metabolism involves rapid hepatic acetylation in all patients.

    <p>False</p> Signup and view all the answers

    Quinidine should be given to patients with long QT syndrome to help manage their arrhythmias.

    <p>False</p> Signup and view all the answers

    The use of procainamide is less restricted than that of quinidine in current medical practice.

    <p>False</p> Signup and view all the answers

    Dosse-related pulmonary toxicity is the most significant adverse effect of calcium channel blockers.

    <p>True</p> Signup and view all the answers

    Verapamil and diltiazem primarily increase heart rate in the treatment of supraventricular tachycardia.

    <p>False</p> Signup and view all the answers

    Calcium channel blockers play a crucial role in the management of ventricular tachycardia.

    <p>False</p> Signup and view all the answers

    Bradycardia and heart block are potential side effects of calcium channel blockers.

    <p>True</p> Signup and view all the answers

    Thyroid dysfunction is caused by the high potassium content in certain medications.

    <p>False</p> Signup and view all the answers

    Corneal microdeposits associated with certain medications may affect vision permanently.

    <p>False</p> Signup and view all the answers

    Photosensitivity can lead to gray-blue skin discoloration in areas exposed to sunlight.

    <p>True</p> Signup and view all the answers

    Verapamil is safe to use in the acute management of ventricular tachycardia.

    <p>False</p> Signup and view all the answers

    Amiodarone is structurally related to cortisol and contains about 40% iodine.

    <p>False</p> Signup and view all the answers

    Dronedarone shares the same chemical structure as amiodarone but does not contain iodine.

    <p>True</p> Signup and view all the answers

    Amiodarone can lead to a wide range of adverse effects due to its long half-life and large volume of distribution.

    <p>True</p> Signup and view all the answers

    The mechanism of action of amiodarone includes blocking calcium channels, which leads to positive inotropic effects.

    <p>False</p> Signup and view all the answers

    Supraventricular arrhythmias can be treated effectively with amiodarone.

    <p>True</p> Signup and view all the answers

    Amiodarone primarily blocks Na+ channels to enhance cardiac excitability.

    <p>False</p> Signup and view all the answers

    Hypothetically, arrhythmia associated with mitral valve prolapse is effectively managed by Class III antiarrhythmic agents.

    <p>True</p> Signup and view all the answers

    Amiodarone has no effect on the effective refractory period of cardiac action potentials.

    <p>False</p> Signup and view all the answers

    Coronary heart disease is responsible for approximately 80% of cardiac arrest cases.

    <p>True</p> Signup and view all the answers

    Pulseless electrical activity (PEA) indicates the absence of any electrical activity in the heart.

    <p>False</p> Signup and view all the answers

    The preferred CPR compression-to-breath ratio is 30:2.

    <p>True</p> Signup and view all the answers

    Epinephrine should be administered when there is no response after the initial defibrillation.

    <p>True</p> Signup and view all the answers

    Ventricular fibrillation is characterized by a flat line on the electrocardiogram (ECG).

    <p>False</p> Signup and view all the answers

    Amiodarone is recommended to be administered at a dose of 1 mg every 3-5 minutes during resuscitation.

    <p>False</p> Signup and view all the answers

    Cardiac arrest can occur due to trauma, electrolyte imbalance, and drugs.

    <p>True</p> Signup and view all the answers

    The electrical defibrillation should be administered at a voltage of 500J.

    <p>False</p> Signup and view all the answers

    What is the primary purpose of anticoagulation after electrical cardioversion?

    <p>To prevent thromboembolic events.</p> Signup and view all the answers

    Describe the main mechanism used in laser ablation for treating arrhythmias.

    <p>Laser ablation uses energy directed through a catheter to disconnect pathways causing abnormal heart rhythms.</p> Signup and view all the answers

    Why is heparinization important before certain cardiac procedures?

    <p>Heparinization reduces the risk of thrombus formation during the procedure.</p> Signup and view all the answers

    What specific arrhythmia can be definitively treated with laser radiofrequency ablation?

    <p>Wolff-Parkinson-White (WPW) syndrome.</p> Signup and view all the answers

    What role do artificial pacemakers serve in cardiac management?

    <p>They monitor and pace the heart's electrical activity.</p> Signup and view all the answers

    What effect does quinidine have on action potential duration (APD) and excitability?

    <p>Quinidine increases action potential duration (APD) and decreases excitability.</p> Signup and view all the answers

    How does quinidine's action at therapeutic doses differ from its action at low doses regarding AV conduction?

    <p>At low doses, quinidine increases AV conduction due to vagolytic action, while at therapeutic doses, it decreases AV conduction due to its direct action.</p> Signup and view all the answers

    How does a catheter function during the laser ablation process?

    <p>It delivers energy to specific heart muscle areas to correct arrhythmias.</p> Signup and view all the answers

    What are the implications of quinidine's negative inotropic effect?

    <p>The negative inotropic effect can lead to decreased myocardial contractility, potentially worsening heart failure.</p> Signup and view all the answers

    Explain how quinidine's blockade of muscarinic and α receptors affects its pharmacological profile.

    <p>Quinidine's blockade of muscarinic and α receptors results in atropine-like effects, causing vasodilation and hypotension.</p> Signup and view all the answers

    What significant anti-malarial effect does quinidine exhibit, and against which organism?

    <p>Quinidine has an anti-malarial effect against Plasmodium falciparum.</p> Signup and view all the answers

    In what ways does quinidine's complex effect on AV conduction complicate its therapeutic use?

    <p>Quinidine's dual actions on AV conduction at different doses can lead to unpredictable effects, complicating its therapeutic use.</p> Signup and view all the answers

    What is the primary reason lidocaine is administered intravenously instead of orally?

    <p>Lidocaine undergoes extensive first-pass metabolism, making oral administration ineffective.</p> Signup and view all the answers

    In which specific acute condition is lidocaine primarily used?

    <p>Lidocaine is used for the acute suppression of ventricular arrhythmia associated with acute myocardial infarction.</p> Signup and view all the answers

    Why is flecainide contraindicated in patients with structural heart disease?

    <p>Flecainide can increase the incidence of ventricular fibrillation and sudden death in these patients.</p> Signup and view all the answers

    What is the mechanism of action of Class II antiarrhythmics like beta blockers?

    <p>Beta blockers decrease sympathetic stimulation, inhibiting phase 4 depolarization and prolonging AV conduction.</p> Signup and view all the answers

    What distinguishes mexiletine from lidocaine in terms of administration?

    <p>Mexiletine can be given orally, while lidocaine is only administered intravenously.</p> Signup and view all the answers

    What role does phenytoin play in the treatment of arrhythmias?

    <p>Phenytoin is primarily used to treat digitalis-induced tachyarrhythmia.</p> Signup and view all the answers

    What effect do beta blockers have on automaticity in cardiac tissues?

    <p>Beta blockers depress automaticity in the cardiac tissues.</p> Signup and view all the answers

    How does lidocaine selectively target damaged tissues?

    <p>Lidocaine is highly selective for damaged tissues because it preferentially blocks Na+ channels in those areas.</p> Signup and view all the answers

    What is the main reason amiodarone can lead to a wide range of adverse effects?

    <p>Amiodarone has a long half-life and large volume of distribution, allowing it to accumulate in various tissues.</p> Signup and view all the answers

    Describe the structural relationship between amiodarone and thyroxine.

    <p>Amiodarone is structurally related to thyroxine, containing about 40% iodine.</p> Signup and view all the answers

    What types of arrhythmias are primarily treated using amiodarone?

    <p>Amiodarone is used to treat both supraventricular and ventricular arrhythmias.</p> Signup and view all the answers

    How does amiodarone affect cardiac excitability?

    <p>Amiodarone blocks Na+ channels, leading to decreased excitability in cardiac tissue.</p> Signup and view all the answers

    Identify a key difference between amiodarone and dronedarone.

    <p>Dronedarone does not contain iodine, unlike amiodarone.</p> Signup and view all the answers

    Explain the mechanism of action of amiodarone that leads to an increased effective refractory period (ERP).

    <p>Amiodarone primarily blocks K+ channels, which slows phase 3 of the action potential.</p> Signup and view all the answers

    What is the significance of amiodarone's long half-life in clinical practice?

    <p>Amiodarone's long half-life necessitates careful dosage regulation to avoid toxicity from accumulation.</p> Signup and view all the answers

    What arrhythmia is associated with Wolff-Parkinson-White (WPW) syndrome?

    <p>Atrial fibrillation (AF) is commonly associated with WPW syndrome.</p> Signup and view all the answers

    What is the underlying issue that characterizes cardiac arrest?

    <p>The cessation of cardiac mechanical activity confirmed by the absence of signs of circulation, such as absent pulse and apnea.</p> Signup and view all the answers

    Identify two common causes of cardiac arrest.

    <p>Coronary heart disease and cardiac arrhythmia, especially ventricular fibrillation.</p> Signup and view all the answers

    What is the purpose of CPR in the management of cardiac arrest?

    <p>To preserve life by restoring circulation through cycles of chest compressions and rescue breaths.</p> Signup and view all the answers

    What is the initial action recommended for a patient in complete asystole?

    <p>Administer 360J electrical defibrillation followed by 2 minutes of CPR.</p> Signup and view all the answers

    Explain the significance of epinephrine administration in cardiac arrest management.

    <p>Epinephrine is given to improve coronary and cerebral perfusion during CPR, enhancing survival rates.</p> Signup and view all the answers

    What distinguishes pulseless electrical activity (PEA) from ventricular fibrillation?

    <p>PEA shows some electrical activity on the ECG but lacks a detectable pulse, whereas ventricular fibrillation exhibits chaotic electrical activity.</p> Signup and view all the answers

    What is the sequence of actions to take if a patient shows no response after defibrillation?

    <p>Continue CPR for 2 minutes and then administer epinephrine 1 mg IV every 3-5 minutes.</p> Signup and view all the answers

    What is the role of amiodarone in the context of cardiac arrest treatment?

    <p>Amiodarone is administered after repeated shocks and CPR to help stabilize the heart's rhythm.</p> Signup and view all the answers

    Quinidine was historically used to treat ______ and ventricular arrhythmias.

    <p>supraventricular</p> Signup and view all the answers

    Cinchonism includes symptoms like tinnitus, headache, and ______.

    <p>diarrhea</p> Signup and view all the answers

    Hypotension can occur after rapid intravenous infusion due to ______ receptor blockade.

    <p>alpha</p> Signup and view all the answers

    Quinidine has an atropine-like action that may increase ______ conduction.

    <p>AV</p> Signup and view all the answers

    Quinidine is rarely used today due to the availability of more ______ and less toxic drugs.

    <p>effective</p> Signup and view all the answers

    Paradoxical tachycardia can occur as a result of quinidine's ______ effects.

    <p>atropine-like</p> Signup and view all the answers

    One of the adverse effects of quinidine is blurred ______.

    <p>vision</p> Signup and view all the answers

    Quinidine was used to maintain sinus rhythm after conversion from atrial ______.

    <p>flutter</p> Signup and view all the answers

    Digitalis or verrapamil should be given before ______ to offer rate control.

    <p>quinidine</p> Signup and view all the answers

    Quinidine can increase the ______ interval and may predispose the patient to torsades de pointes.

    <p>QT</p> Signup and view all the answers

    Procainamide is equivalent to quinidine as an antiarrhythmic agent and has similar cardiac and ______ effects.

    <p>toxic</p> Signup and view all the answers

    Long-term therapy with procainamide can lead to drug-induced systemic lupus ______ after long term therapy.

    <p>erythematosus</p> Signup and view all the answers

    Quinidine should not be given to patients with long QT syndrome or with other drugs that ______ the QT interval.

    <p>increase</p> Signup and view all the answers

    30% of patients, who are slow acetylators, develop drug-induced systemic lupus ______ after long-term therapy with procainamide.

    <p>erythematosus</p> Signup and view all the answers

    The use of ______ is now very limited, much like quinidine.

    <p>procainamide</p> Signup and view all the answers

    Both quinidine and procainamide are classified as subclass ______ antiarrhythmics.

    <p>1A</p> Signup and view all the answers

    Lidocaine is exclusively a ______ channel blocker.

    <p>Na+</p> Signup and view all the answers

    Lidocaine undergoes extensive first-pass ______, so it is not given orally.

    <p>metabolism</p> Signup and view all the answers

    Flecainide blocks both Na+ and ______ channels.

    <p>K+</p> Signup and view all the answers

    Class II beta blockers inhibit phase 4 ______.

    <p>depolarization</p> Signup and view all the answers

    Mexiletine is used primarily for long-term treatment of ______ arrhythmias.

    <p>ventricular</p> Signup and view all the answers

    Phenytoin is primarily used in the treatment of digitalis-induced ______.

    <p>tachyarrhythmia</p> Signup and view all the answers

    Flecainide is contraindicated for patients with ischemic heart disease or structural heart ______.

    <p>disease</p> Signup and view all the answers

    Beta blockers are used for all arrhythmias induced by sympathetic ______.

    <p>overactivity</p> Signup and view all the answers

    Amiodarone is structurally related to ______ and contains approximately 40% iodine.

    <p>thyroxine</p> Signup and view all the answers

    Dronedarone is chemically similar to amiodarone but does not contain ______.

    <p>iodine</p> Signup and view all the answers

    Amiodarone blocks mainly ______ channels, contributing to the slowing of phase 3.

    <p>K+</p> Signup and view all the answers

    Amiodarone has a long half-life (t½) and large volume of distribution (Vd), leading to ______ in many tissues.

    <p>accumulation</p> Signup and view all the answers

    Amiodarone exerts negative inotropic and chronotropic effects by blocking ______ channels.

    <p>Ca</p> Signup and view all the answers

    Amiodarone is used for supraventricular and ______ arrhythmia treatment.

    <p>ventricular</p> Signup and view all the answers

    Amiodarone can be effective for arrhythmia resistant to other ______.

    <p>drugs</p> Signup and view all the answers

    The mechanism of action of amiodarone includes blocking Na+ channels, which leads to decreased ______.

    <p>excitability</p> Signup and view all the answers

    The patient should be _______ before the procedure.

    <p>heparinized</p> Signup and view all the answers

    Following electrical cardioversion, patients should be anticoagulated for at least ____ weeks.

    <p>4</p> Signup and view all the answers

    Laser ablation is used for many types of _________.

    <p>arrhythmias</p> Signup and view all the answers

    A catheter is inserted into a specific area of the ______.

    <p>heart</p> Signup and view all the answers

    Laser radiofrequency ablation is the definite treatment of _______ syndrome.

    <p>WPW</p> Signup and view all the answers

    Artificial pacemakers are implanted under the skin or in the chest ______ to monitor and pace the heart.

    <p>cavity</p> Signup and view all the answers

    Match the following effects of Quinidine with their descriptions:

    <p>Vagal effects = Increased AV conduction at low doses Negative inotropic effect = Decreased force of contraction Antimalarial effect = Active against P. falciparum Atropine-like action = Blocks muscarinic and α receptors</p> Signup and view all the answers

    Match the following dosing scenarios of Quinidine with their corresponding effects on AV conduction:

    <p>Low doses = Increased AV conduction Therapeutic doses = Decreased AV conduction High doses = Escalation in vagolytic effects Initial loading dose = Transient increase in excitability</p> Signup and view all the answers

    Match the Quinidine mechanism with its effects:

    <p>Blocks Na+ channels = Decreases rate of phase-0 depolarization Blocks muscarinic receptors = Leads to vagolytic effects Effects on action potential = Increases APD and ERP Negative inotropic effect = Decrease in cardiac contractility</p> Signup and view all the answers

    Match the following aspects of Quinidine with their implications:

    <p>Vagolytic action = Hypotension risk Complex effects on AV conduction = Potential for arrhythmias Antiarrhythmic use = Inconsistent AV conduction response Long-term use consequences = Possible symptoms of cinchonism</p> Signup and view all the answers

    Match the following descriptions of adverse effects associated with Quinidine:

    <p>Cinchonism = Tinnitus and headaches Hypotension = Due to vagolytic action Negative inotropic effect = Increased risk of heart failure Torsades de pointes = Prolonged QT interval risk</p> Signup and view all the answers

    Match the following conditions regarding Quinidine with their characteristics:

    <p>Therapeutic doses = Predominantly decrease AV conduction Vagal effects = Enhanced AV conduction at lower doses Mechanism of action = Involves blocking Na+ and other receptors Clinical relevance = Limited use due to side effects</p> Signup and view all the answers

    Match the antiarrhythmic agents with their characteristics:

    <p>Adenosine = Contraindicated in asthma due to potential bronchospasm Amiodarone = Contains high levels of iodine Dronedarone = Does not contain iodine Quinidine = Positive inotropic effect on cardiac muscle</p> Signup and view all the answers

    Match the usage of different electrical intervention methods in arrhythmias:

    <p>Direct Current Cardioversion = Emergency control of rapid AF in unstable patients Electrical Cardioversion = Utilized for rhythm restoration in persistent AF Defibrillation = Used for ventricular fibrillation Pacing = Provides electrical stimulus to manage bradycardia</p> Signup and view all the answers

    Match the antiarrhythmic concept with its description:

    <p>Half-life of Adenosine = 8-10 seconds Adenosine mechanism = Opens K+ channels and inhibits Ca2+ channels Cardioversion method = Application of electric shock to the chest Adenosine dosage = 6 mg i.v. bolus followed by 12 mg if necessary</p> Signup and view all the answers

    Match the arrhythmias with the respective treatment methods:

    <p>Wolff-Parkinson-White syndrome = Definitive treatment is ablation Atrial Fibrillation = Direct Current Cardioversion Supraventricular Tachycardia = Adenosine administration Ventricular Fibrillation = Defibrillation required</p> Signup and view all the answers

    Match the side effects or interactions with their respective agents:

    <p>Adenosine with caffeine = Decreased efficacy of adenosine Adenosine in asthmatics = Can cause bronchospasm Quinidine and long QT syndrome = Potential exacerbation of arrhythmias Procainamide = Risk of drug-induced lupus erythematosus</p> Signup and view all the answers

    Match the antiarrhythmic agents with their primary mechanism:

    <p>Adenosine = Purinergic A1 receptor agonist Quinidine = Acts primarily on K+ channels Amiodarone = Multiple mechanisms including ion channel blockade Dronedarone = Selective blocking of potassium ion channels</p> Signup and view all the answers

    Match the drug names with their specific dosing recommendations:

    <p>Adenosine = 6 mg i.v. bolus, then 12 mg if needed Quinidine = Titration based on patient response Amiodarone = Loading dose followed by maintenance dose Dronedarone = 600 mg bid with food</p> Signup and view all the answers

    Match the terms with their definitions in cardiology:

    <p>Bronchospasm = Contraction of airway muscles typically seen in asthma Supraventricular Tachycardia = Rapid heart rate originating above the ventricles Cardiac Dysrhythmia = Abnormal heart rhythm Hyperpolarization = Increased negativity of the membrane potential</p> Signup and view all the answers

    Match the following antiarrhythmic agents with their primary indications:

    <p>Lidocaine = Acute suppression of ventricular arrhythmias associated with acute MI Mexiletine = Long-term treatment of ventricular arrhythmias Flecainide = Atrial and ventricular arrhythmia Phenytoin = Digitalis-induced tachyarrhythmia</p> Signup and view all the answers

    Match the following pharmacological actions with their corresponding antiarrhythmic class:

    <p>Beta blockers = ↓ sympathetic stimulation Flecainide = Blocks Na+ and K+ channels Lidocaine = Na+ channel blocker Phenytoin = Class 1B activity</p> Signup and view all the answers

    Match the following statements about antiarrhythmic drugs with their respective characteristics:

    <p>Lidocaine = Not given orally due to first-pass metabolism Flecainide = Contraindicated in patients with ischemic heart disease Mexiletine = Can be given orally Phenytoin = Used primarily for digitalis-induced tachyarrhythmia</p> Signup and view all the answers

    Match the following adverse effects with the antiarrhythmic agents they are associated with:

    <p>Lidocaine = Neurologic effects Flecainide = Increased incidence of ventricular fibrillation Phenytoin = Limited role in other ventricular arrhythmias Mexiletine = Similar profile to lidocaine</p> Signup and view all the answers

    Match the following characteristics of arrhythmia treatments with the appropriate agents:

    <p>Lidocaine = Only intravenous administration Flecainide = Used for maintenance of sinus rhythm Mexiletine = Long-term ventricular arrhythmia management Phenytoin = IV loading dose over 10 minutes</p> Signup and view all the answers

    Match the following effects of antiarrhythmic drugs with their mechanisms of action:

    <p>Beta blockers = Depress automaticity Lidocaine = Highly selective for damaged tissues Flecainide = Slows AV conduction Phenytoin = Phase 0 depolarization effect</p> Signup and view all the answers

    Match the following arrhythmia treatments with their routes of administration:

    <p>Lidocaine = Intravenous only Mexiletine = Oral Phenytoin = Intravenous Flecainide = Oral for atrial flutter maintenance</p> Signup and view all the answers

    Match the following antiarrhythmic effects with their classes:

    <p>Class 1B = Na+ channel blockade Class 1C = Na+ and K+ channel blockade Class II = ↓ heart rate Class 1A = Ventricular arrhythmia management</p> Signup and view all the answers

    Match the following procedures with their descriptions:

    <p>Heparinization = Patient preparation before a procedure Anticoagulation after electrical cardioversion = At least 4 weeks of treatment Laser ablation = Energy is directed through a catheter to correct arrhythmias Artificial pacemakers = Battery-powered devices to monitor and pace the heart</p> Signup and view all the answers

    Match the arrhythmia treatment with its specific function:

    <p>Laser radiofrequency ablation = Definitive treatment for WPW syndrome Catheter insertion = Targets specific areas of the heart Electrical cardioversion = Restores normal heart rhythm Anticoagulation = Prevents thromboembolic events post-cardioversion</p> Signup and view all the answers

    Match the following concepts with their purposes:

    <p>Heparin administration = Prevention of clot formation before surgery Anticoagulation therapy duration = Ensures stable heart rhythm post-procedure Ablation energy = Disrupts abnormal electrical pathways in the heart Pacemaker function = Maintains appropriate heart rate and rhythm</p> Signup and view all the answers

    Match the following cardiac interventions with their characteristics:

    <p>Anticoagulation = Maintains heart health after procedures Catheter ablation method = Uses energy to disconnect abnormal rhythms Electrical cardioversion timing = Requires monitoring for weeks post-procedure Implantation of defibrillators = Provides emergency cardiac pacing and shock</p> Signup and view all the answers

    Match the following arrhythmia-related terms with their definitions:

    <p>Arrhythmias = Abnormal heart rhythms requiring treatment Heparinization = Initiation of heparin therapy before a procedure Ablation process = Targeted destruction of abnormal heart tissue Wolff-Parkinson-White syndrome = Condition effectively treated with laser ablation</p> Signup and view all the answers

    Match the heart device types with their functionalities:

    <p>Artificial pacemakers = Monitors and maintains heart rhythm Implantable cardioverter defibrillators = Delivers shocks for life-threatening arrhythmias Laser ablation catheters = Corrects arrhythmias via energy application Anticoagulants post-procedure = Reduces risk of blood clot formation</p> Signup and view all the answers

    Match the following antiarrhythmic agents with their characteristics:

    <p>Quinidine = Prolongs QT interval and may cause torsades de pointes Procainamide = Metabolized by hepatic acetylation Digitalis = Improves AV conduction when used with quinidine Verrapamil = Used for rate control in arrhythmias</p> Signup and view all the answers

    Match the following conditions with the appropriate antiarrhythmic recommendation:

    <p>Long QT syndrome = Avoid quinidine Drug-induced systemic lupus erythematosus = Associated with procainamide long-term therapy Torsades de pointes = Risk increased with quinidine use Cinchonism = Possible effect of quinidine</p> Signup and view all the answers

    Match the following statements to their corresponding antiarrhythmic drug:

    <p>Procainamide = Similar cardiac effects as quinidine Quinidine = Historically used for treating arrhythmias Verrapamil = Rate control drug, affects AV conduction Digitalis = May be used before quinidine</p> Signup and view all the answers

    Match the following characteristics with the correct arrhythmic treatment:

    <p>Quinidine = Not recommended for patients with long QT syndrome Procainamide = Adverse effects include lupus-like syndrome Digitalis = Administered before quinidine for rate control Verrapamil = Acts by reducing AV node conduction</p> Signup and view all the answers

    Match the following adverse effects with their respective antiarrhythmic drugs:

    <p>Quinidine = Prolongs QT interval leading to arrhythmias Procainamide = Can cause drug-induced lupus Digitalis = Improves AV conduction Verrapamil = Given after quinidine for rate control</p> Signup and view all the answers

    Match the following drugs with their usage recommendations:

    <p>Quinidine = Not prescribed due to significant side effects Procainamide = Limited use due to toxicity considerations Digitalis = Used to manage heart rate Verrapamil = Effective for rate control in arrhythmias</p> Signup and view all the answers

    Match the following terms related to antiarrhythmic drugs with their definitions:

    <p>Acetylation = Metabolic process affecting procainamide Torsades de pointes = Severe arrhythmia linked to QT prolongation Cinchonism = Side effect associated with quinidine Systemic lupus erythematosus = Possible outcome of prolonged procainamide use</p> Signup and view all the answers

    Match the following antiarrhythmic drugs with their primary mechanism of action:

    <p>Quinidine = Affects Na+ and K+ channel activity Procainamide = Blocks Na+ channels similar to quinidine Digitalis = Increases vagal tone to control heart rate Verrapamil = Calcium channel blocker to manage arrhythmias</p> Signup and view all the answers

    Study Notes

    Quinidine Overview

    • Class 1A antiarrhythmic drug.
    • Mechanism: Blocks activated Na+ channels, decreasing phase-0 depolarization, excitability, and increasing action potential duration (APD) and effective refractory period (ERP).
    • Effects: Vagal stimulation leads to increased AV conduction at low doses; direct action decreases AV conduction at therapeutic doses.
    • Additional actions: Blocks muscarinic and α receptors causing vagolytic effects and hypotension.
    • Indications: Previously used for supraventricular and ventricular arrhythmias and to maintain sinus rhythm post-atrial flutter and fibrillation; usage has declined due to availability of safer alternatives.

    Adverse Effects and Precautions

    • Cinchonism: Symptoms include tinnitus, headache, blurred vision, vomiting, and diarrhea.
    • Hypotension: Can occur after rapid IV infusion due to α-receptor blockade.
    • Paradoxical tachycardia: Quinidine's atropine-like action can increase AV conduction and cause "paradoxical tachycardia."
    • Risk factors: Associated with arrhythmias in hypertrophic obstructive cardiomyopathy (HOCM) and mitral valve prolapse.

    Amiodarone Overview

    • Class III antiarrhythmic drug, structurally similar to thyroxine, containing ~40% iodine.
    • Mechanism: Blocks K+ channels, slowing phase 3 and increasing ERP; blocks Na+ channels and Ca2+ channels.
    • Pharmacokinetics: Long half-life and large volume of distribution lead to accumulation and various adverse effects.
    • Indications: Used for both supraventricular and ventricular arrhythmias, including Wolff-Parkinson-White (WPW) syndrome and refractory arrhythmias.

    Adenosine Overview

    • Purinergic A1 receptor agonist, opens K+ channels and inhibits Ca2+ channels, causing hyperpolarization and inhibiting AV nodal conduction.
    • Extremely short half-life of 8-10 seconds.
    • Drug of choice for immediate termination of paroxysmal supraventricular tachycardia, administered as a 6 mg IV bolus followed by 12 mg if necessary.
    • Less effective with adenosine receptor blockers (e.g., theophylline, caffeine) and contraindicated in asthma patients due to potential bronchospasm.

    Non-Pharmacological Methods

    DC Cardioversion

    • Direct current delivery via electric shock for emergency control of arrhythmias, especially unstable rapid AF.
    • Patients should be heparinized prior to the procedure and anticoagulated post-procedure for at least 4 weeks.

    Laser Ablation

    • Catheter insertion into specific heart areas, where energy is applied to abnormal rhythm-causing tissue.
    • Laser radiofrequency ablation is definitive treatment for WPW syndrome.

    Artificial Pacemakers and Implantable Cardioverter-Defibrillators

    • Battery-powered devices implanted under the skin or in the chest cavity to monitor and pace the heart.

    Quinidine (Subclass 1A)

    • Blocks activated Na+ channels, decreasing phase-0 depolarization rate, excitability, increases action potential duration (APD) and effective refractory period (ERP).
    • Inhibits muscarinic and α receptors, leading to atropine-like vasodilatory effects and hypotension.
    • Effects on AV conduction are complex:
      • Low doses enhance AV conduction due to predominant vagolytic action.
      • Therapeutic doses reduce AV conduction via direct action.
    • Exhibits negative inotropic effects and has anti-malarial properties against Plasmodium falciparum.
    • Must administer digitalis or verapamil prior to quinidine to control AV conduction and heart rate.
    • Can prolong QT interval, posing a risk for serious arrhythmias (like Torsades de Pointes).
    • Contraindicated in patients with long QT syndrome.

    Procainamide (Subclass 1A)

    • Comparable antiarrhythmic agent to quinidine with akin cardiac and toxic effects; currently used less frequently.
    • Metabolized by hepatic acetylation; 30% of patients (slow acetylators) may develop drug-induced systemic lupus erythematosus (SLE) with long-term use.
    • Effective for arrhythmias associated with hypertrophic obstructive cardiomyopathy (HOCM) and supraventricular arrhythmias (such as atrial fibrillation).

    Amiodarone (Class III)

    • Structurally related to thyroxine with approximately 40% iodine content; dronedarone is a similar compound without iodine.
    • Long half-life and high volume of distribution lead to tissue accumulation and various adverse effects.
    • Mechanism of action:
      • Mainly blocks K+ channels, slowing phase 3 depolarization, thus increasing ERP.
      • Also blocks Na+ channels, reducing excitability.
      • Blocks Ca2+ channels, leading to negative inotropic and chronotropic effects.
    • Used for both supraventricular and ventricular arrhythmias, as well as Wolff-Parkinson-White (WPW) syndrome.
    • Adverse effects include dose-related pulmonary toxicity (fibrosis), hepatic toxicity, thyroid dysfunction, corneal microdeposits (reversible), bradycardia, heart block, and photosensitivity leading to skin discoloration.

    Calcium Channel Blockers (Class IV: Verapamil and Diltiazem)

    • Mechanism of action: decrease activity in the Sinoatrial Node (SAN) and AV conduction.
    • Primarily used to reduce heart rate in supraventricular tachycardia and arrhythmias linked to HOCM.
    • Not recommended for chronic management of ventricular tachycardia (VT).
    • Acute use in VT is contraindicated due to potential for hemodynamic collapse.

    Management of Cardiac Arrest

    • Cardiac arrest characterized by cessation of mechanical heart activity, confirmed by absence of circulation signs (absent pulse and apnea).
    • Common causes include coronary heart disease (~80%), cardiac conditions (HOCM, Brugada syndrome), arrhythmias (especially ventricular), trauma, electrolyte imbalances, electrical shock, and drug-related issues.
    • Patterns of cardiac arrest:
      • Asystole: Flat line on ECG.
      • Ventricular fibrillation: ECG shows fibrillation waves.
      • Pulseless electrical activity (PEA): Electrical activity present without detectable pulse.
    • Treatment aims to preserve life with early CPR (30:2 cycles).
    • Additional management steps include:
      • Electrical defibrillation at 360J followed by 2 minutes of CPR.
      • If no response, administer epinephrine 1 mg IV every 3-5 minutes with CPR.
      • If still unresponsive, apply DC shocks and continue CPR for 2 minutes.
      • Administer amiodarone 300 mg IV if no response persists.

    Quinidine (Class 1A)

    • Blocks activated Na+ channels, leading to decreased phase-0 depolarization, reduced excitability, increased action potential duration (APD), and increased effective refractory period (ERP).
    • Inhibits muscarinic and α-adrenergic receptors, producing atropine-like (vagal) effects and causing hypotension.
    • Exhibits complex effects on AV conduction:
      • At low doses, vagolytic action increases AV conduction.
      • At therapeutic doses, direct action decreases AV conduction.
    • Has a negative inotropic effect and is an effective antimalarial against Plasmodium falciparum.

    Lidocaine (Class 1B)

    • A selective Na+ channel blocker, primarily acting on damaged cardiac tissues; not administered orally due to extensive first-pass metabolism.
    • Used intravenously for acute ventricular arrhythmia management, particularly after myocardial infarction (MI). Typical dose is 50-100 mg IV, repeat half dose after 5-10 minutes if required.
    • Has no effect on AV conduction; not suitable for supraventricular arrhythmias.
    • Adverse effects are predominantly neurologic.
    • Mexiletine, similar to lidocaine, is orally available for long-term ventricular arrhythmia treatment post-MI.
    • Phenytoin, an antiepileptic with Class 1B activity, primarily treats digitalis-induced tachyarrhythmia and has limited use for other ventricular arrhythmias. IV loading dose is 250 mg over 10 minutes.

    Flecainide (Class 1C)

    • Blocks both Na+ and K+ channels, decreasing phase-0 depolarization and slowing AV conduction; APD remains unchanged.
    • Utilized for atrial and ventricular arrhythmias and maintaining sinus rhythm post-conversion from atrial flutter and fibrillation.
    • Increases risk of ventricular fibrillation and sudden death post-MI (proarrhythmic effect), contraindicated in ischemic or structurally compromised hearts.

    Class II: Beta Blockers

    • Reduce sympathetic stimulation by inhibiting phase 4 depolarization, decreasing automaticity, prolonging AV conduction, decreasing heart rate, and lowering contractility.

    Therapeutic Uses of Beta Blockers

    • Effective for arrhythmias induced by sympathetic overactivity, thyrotoxicosis, hypertrophic obstructive cardiomyopathy (HOCM), supraventricular arrhythmias like atrial fibrillation, and arrhythmias associated with mitral valve prolapse.

    Amiodarone (Class III)

    • Structurally related to thyroxine with ~40% iodine content; Dronedarone is similar but iodine-free.
    • Long half-life and large volume of distribution lead to accumulation in various tissues, causing diverse adverse effects.
    • Mechanism of action:
      • Primarily blocks K+ channels, slowing phase 3 depolarization, increasing ERP.
      • Also inhibits Na+ channels, reducing excitability, and blocks Ca2+ channels, producing negative inotropic and chronotropic effects.

    Therapeutic Uses of Amiodarone

    • Treats both supraventricular and ventricular arrhythmias, including Wolff-Parkinson-White syndrome and arrhythmias resistant to other drugs.
    • Patients may require heparinization prior to procedures and anticoagulation for at least 4 weeks after electrical cardioversion.

    Laser Ablation

    • Involves catheter insertion into specific heart areas; utilizes directed energy to treat abnormal rhythms.
    • Radiofrequency ablation is the definitive treatment for WPW syndrome.

    Artificial Pacemakers and Implantable Cardioverter Defibrillators

    • Battery-powered devices implanted under the skin or in the chest to monitor and regulate heart rhythm.

    Management of Cardiac Arrest

    • Cardiac arrest signifies cessation of mechanical cardiac activity with no circulation signs (absent pulse and apnea).
    • Major causes include coronary heart disease (~80%), cardiac conditions (e.g., HOCM, Brugada syndrome), arrhythmias, trauma, electrolyte imbalances, and drugs.

    Patterns of Arrest

    • Complete asystole: ECG displays a flat line.
    • Ventricular fibrillation: ECG presents fibrillation waves.
    • Pulseless electrical activity (PEA): Some electrical activity present without detectable pulse.

    Management Protocol for Cardiac Arrest

    • Initial goal: preserve life through early CPR (30 chest compressions followed by 2 rescue breaths).
    • Initiate electrical defibrillation (360J), then resume CPR for 2 minutes.
    • If unresponsive, administer epinephrine (1 mg IV every 3-5 minutes with CPR).
    • Continue with direct current (DC) shock if no response; administer amiodarone (300 mg IV) with ongoing CPR.

    Therapeutic Uses of Antiarrhythmic Drugs

    • Quinidine: Historically used for supraventricular and ventricular arrhythmias; now rarely prescribed due to availability of more effective, less toxic alternatives.
    • Procainamide: Comparable to quinidine; limited use due to similar effects and risk of drug-induced systemic lupus erythematosus (SLE) in some patients.
    • Lidocaine: Selectively blocks Na+ channels, primarily used intravenously for acute ventricular arrhythmias, especially post-myocardial infarction (MI). Oral administration is avoided due to extensive first-pass metabolism.
    • Flecainide: Blocks both Na+ and K+ channels, suppressing atrial and ventricular arrhythmias. Risks include increased chances of ventricular fibrillation and sudden death after MI, making it contraindicated for patients with ischemic or structural heart disease.

    Class II: Beta Blockers

    • Reduce sympathetic stimulation, which inhibits phase 4 depolarization and depresses automaticity.
    • Therapeutic applications: Manage arrhythmias induced by sympathetic overactivity, thyrotoxicosis, hypertrophic obstructive cardiomyopathy (HOCM), atrial fibrillation (AF), and mitral valve prolapse.

    Class III: Amiodarone

    • Structurally related to thyroxine, contains about 40% iodine; dronedarone shares similar properties but without iodine.
    • Long half-life and large volume of distribution allow tissue accumulation, leading to diverse side effects.
    • Mechanism: Primarily blocks K+ channels, slowing phase 3 repolarization, and also blocks Na+ and Ca2+ channels, reducing excitability and providing negative inotropic and chronotropic effects.
    • Used for a wide range of arrhythmias, including supraventricular and ventricular types, Wolff-Parkinson-White (WPW) syndrome, and refractory rhythms.

    Laser Ablation Therapy

    • Utilizes a catheter inserted into specific heart areas; energy is directed to ablate abnormal cardiac tissue responsible for irregular rhythms.
    • Effective in treating various arrhythmias and is the definitive treatment for WPW syndrome.

    Implantable Devices

    • Artificial pacemakers and implantable cardioverter-defibrillators (ICDs) are battery-powered devices implanted under the skin to monitor heart rhythms and provide pacing as needed.

    Quinidine (Subclass 1A)

    • Blocks activated Na+ channels, reducing phase-0 depolarization, excitability, while increasing action potential duration (APD) and effective refractory period (ERP).
    • Antagonizes muscarinic and α receptors resulting in atropine-like vagolytic and hypotensive effects.
    • Exhibits dual actions on AV conduction:
      • At low doses, it enhances AV conduction due to vagolytic activity.
      • At therapeutic doses, it decreases AV conduction due to direct action.
    • Has negative inotropic effects and anti-malarial properties against Plasmodium falciparum.
    • Prior administration of digitalis or verapamil may help control AV conduction rate.
    • Prolongs QT interval and predisposes patients to torsades de pointes; contraindicated in patients with long QT syndrome.

    Procainamide (Subclass 1A)

    • Comparable to quinidine as an antiarrhythmic agent with similar cardiac effects and toxicity.
    • Limited usage in modern medicine.
    • May cause drug-induced systemic lupus erythematosus (SLE) in slow acetylators after long-term therapy.

    Lidocaine (Subclass 1B)

    • Exclusively a Na+ channel blocker, highly selective for damaged tissues.
    • Undergoes extensive first-pass metabolism; not suitable for oral administration.
    • Administered intravenously for acute ventricular arrhythmias associated with myocardial infarction (MI).
    • Does not affect AV conduction; not indicated for supraventricular arrhythmias.
    • Common adverse effects are primarily neurological.
    • Mexiletine, related to lidocaine, is orally effective for long-term ventricular arrhythmia management.
    • Phenytoin, an antiepileptic, has class 1B activity useful in digitoxin-induced tachyarrhythmias.

    Flecainide (Subclass 1C)

    • Blocks both Na+ and K+ channels, slowing phase-0 depolarization and AV conduction without altering action potential duration.
    • Indicated for atrial and ventricular arrhythmias and maintenance of sinus rhythm post-conversion from atrial flutter/fibrillation.
    • Increases risk of ventricular fibrillation and sudden death post-MI; contraindicated in patients with ischemic or structural heart disease.

    Class II: Beta Blockers

    • Reduce sympathetic stimulation, inhibit phase 4 depolarization, decrease automaticity, prolong AV conduction, increase heart rate, and reduce contractility.
    • Used for arrhythmias induced by sympathetic overactivity and those related to thyrotoxicosis.

    Adenosine

    • Acts as a purinergic A1 receptor agonist, enhancing K+ channel opening and inhibiting Ca2+ channels, leading to hyperpolarization in the AV system.
    • Short half-life of 8-10 seconds.
    • First-line treatment for rapid termination of paroxysmal supraventricular tachycardia, administered as an i.v. bolus.
    • Efficacy reduced in the presence of adenosine receptor blockers such as theophylline or caffeine.
    • Should not be used in patients with asthma due to bronchospasm risk.

    Non-Pharmacological Methods

    DC Cardioversion

    • Application of direct current shock to the chest wall for rapid arrhythmia control, especially in unstable patients.
    • Important to anticoagulate patients post-procedure.

    Laser Ablation

    • Targets specific cardiac areas via catheter insertion to treat various arrhythmias by disconnecting abnormal impulse pathways.
    • Radiofrequency ablation is the definitive treatment for Wolff-Parkinson-White syndrome.

    Artificial Pacemakers and Implantable Cardioverter-Defibrillators

    • Battery-powered devices implanted under the skin or in the chest cavity to monitor and regulate heart rhythms.

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    Quinidine (Subclass 1A) Pharmacology PDF

    Description

    This quiz focuses on the pharmacological effects and mechanisms of Quinidine, a medication used in treating cardiac arrhythmias. It covers its action on activated Na+ channels, effects on phase-0 depolarization, excitability, and action potential duration. Dive in to test your understanding of this vital topic in pharmacology.

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