Anti-Anginal Effect of Calcium Channel Blockers
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Questions and Answers

Which of the following subclass IA antiarrhythmic preparations is rarely used for supraventricular arrhythmias?

  • Mexiletine
  • Quinidine (correct)
  • Procainamide
  • Lidocaine

What is the primary indication for IV procainamide in subclass IA?

  • Hemodynamically unstable ventricular tachycardia
  • Hemodynamically stable ventricular tachycardia (correct)
  • Supraventricular arrhythmias
  • Refractory ventricular arrhythmias

What is the mechanism of action of beta-adrenoblocker preparations?

  • Blockade of myocardial β–adrenergic receptors (correct)
  • Increase of AV conduction
  • Enhancement of phase 4 depolarization
  • Stimulation of the SA node

Which of the following subclass IB antiarrhythmic preparations is used for chronic treatment of ventricular arrhythmias?

<p>Mexiletine (C)</p> Signup and view all the answers

What is the primary indication for flecainide in subclass IC?

<p>Prophylaxis in paroxysmal atrial fibrillation (B)</p> Signup and view all the answers

What is the effect of beta-adrenoblocker preparations on the SA node?

<p>Slow the rate of the SA node (C)</p> Signup and view all the answers

Which of the following subclass IA antiarrhythmic preparations is used for acute conversion of atrial fibrillation?

<p>Procainamide (C)</p> Signup and view all the answers

What is the effect of beta-adrenoblocker preparations on AV conduction?

<p>Decrease AV conduction (B)</p> Signup and view all the answers

What is the primary indication for lidocaine in subclass IB?

<p>Ventricular arrhythmias (D)</p> Signup and view all the answers

What is the effect of beta-adrenoblocker preparations on automaticity?

<p>Suppress automaticity (A)</p> Signup and view all the answers

Study Notes

Antianginal Effects of Calcium Channel Blockers

  • Coronary artery dilatation and relief of coronary spasm (variant angina)
  • Decrease myocardial O2 demand due to:
    • Arteriolar dilatation, decreasing vascular resistance and afterload
    • Decrease in heart rate (HR)
    • Decrease in contractility
    • Decrease in AV conductivity

Preparations Used to Abolish Angina Pectoris Attacks

  • Organic nitrates:
    • Nitroglycerin
    • Isosorbide dinitrate
    • Isosorbide mononitrate
    • Trinitrolong
    • Nitrong
  • Ca channel blocking drugs:
    • Nifedipine
    • Diltiazem
    • Verapamil
    • Mibefradil
  • K channel activators:
    • Minoxidil
    • Pinacidil
    • Nicorandil
    • Diazoxide
  • Various drugs:
    • Amiodarone

Groups and Preparations Used in Acute Myocardial Infarction

  • Opioid drugs:
    • Fentanyl
    • Morphine
    • Trimeperidine
  • Anxiolytics:
    • Tranquilizers (diazepam)
    • Neuroleptics
    • Neurolepanalgesia (fentanyl, droperidol or talamonal)
  • Prevention of arrhythmias:
    • Antiarrhythmics (lidocaine)
  • Improvement of circulation:
    • Hexamethonium
    • Furasemide
    • Triperium iodide
    • Dopamine
    • Norepinephrine
    • Phenylephrine
  • Prevention of thromboses:
    • Anticoagulators (heparin)
    • Antiaggregants (fibrinolysine, aspirin)
  • Acido-base equilibrium:
    • Na bicarbonate
    • Dextran 40, 70
  • Cardiac failure:
    • Cardiotonics (dopamine, glycosides)
  • Decrease necrotic area:
    • Nitroglycerine
  • Amelioration of myocardial metabolism:
    • Cardioprotectors (omopatrylate, trimethasidine)
    • Antioxidants (coenzyme Q10)

Adenosine

  • Based on the influence on the efferent cardiac innervations
  • Remedies that stimulate the adrenergic influence:
    • β adrenomimetics (izoprenaline)
    • Sympathomimetics (ephedrine)
  • Remedies with cholinergic influence:
    • Anticholinesterases (Edrophonium)
    • α adrenomimetics (phenylephrine)
  • Remedies that decrease cholinergic action:
    • Atropine

Antiarrhythmic Preparations

  • Class II – Beta-adrenoblockers:
    • Propranolol
    • Metoprolol
    • Nadolol
    • Atenolol
    • Acebutolol
    • Pindolol
    • Sotalol
    • Timolol
    • Esmolol
  • Class III – K+ channel blockers:
    • Amiodarone
    • Ibutilide
    • Bretylium
    • Dofetilide
    • Sotalol
  • Class IV - Ca2+ channel blockers:
    • Verapamil
    • Diltiazem
    • Galapamil
    • Nifidifin
    • Alinidin

Indications for Antiarrhythmic Preparations

  • Subclass IA:
    • Supraventricular (atrial) and ventricular arrhythmias
    • Quinidine is rarely used for supraventricular arrhythmias
    • Oral quinidine/procainamide are used with class III drugs in refractory ventricular tachycardia patients with implantable defibrillator
    • IV procainamide used for hemodynamically stable ventricular tachycardia
    • IV procainamide is used for acute conversion of atrial fibrillation including Wolff-Parkinson-White Syndrome (WPWS)
  • Subclass IB:
    • Lidocaine is the drug of choice in emergency treatment of ventricular arrhythmias
    • Mexiletine is used for chronic treatment of ventricular arrhythmias associated with previous myocardial infarction
    • They are used in the treatment of ventricular arrhythmias arising during myocardial ischemia or due to digoxin toxicity
    • They have little effect on atrial or AV junction arrhythmias (because they don’t act on conduction velocity)
  • Subclass IC:
    • Refractory ventricular arrhythmias
    • Flecainide is a particularly potent suppressant of premature ventricular contractions (beats)
    • Supraventricular arrhythmias
    • Flecainide: Prophylaxis in paroxysmal AF

Mechanism of Action and Antiarrhythmic Effect of Beta-Adrenoblocker Preparations

  • Blockade of myocardial β–adrenergic receptors
  • Direct membrane-stabilizing effects related to Na+ channel blockade
  • Slows SA node and ectopic pacemaking
  • Increase refractory period
  • Negative inotropic and chronotropic action
  • Prolong (decrease) AV conduction (delay)
  • Diminish phase 4 depolarization, suppressing automaticity (of ectopic focus)

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Description

This quiz assesses the anti-anginal effects of calcium channel blockers, including coronary artery dilation, decreased myocardial O2 demand, and decreased O2 consumption.

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