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Related Concept Videos

Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers01:12

Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers

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Class III antiarrhythmic drugs are a group of medications that can prolong action potentials in the heart. They achieve this by blocking potassium channels or enhancing inward currents from sodium channels. However, these drugs have a unique property of "reverse use-dependence," which is most pronounced at slower heart rates and can lead to torsades de pointes—a specific type of arrhythmia. However, it is essential to note that excessive QT interval prolongation—a measure of...
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Dysrhythmias II: Classification of Tachyarrhythmias01:28

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Tachyarrhythmias are a type of dysrhythmia where the heart rate exceeds 100 beats per minute. Here are some common types of tachyarrhythmias:Sinus TachycardiaSinus tachycardia originates from increased impulses from the sinus node, leading to an elevated heart rate. It is often triggered by stress, fever, or exercise.Patients may experience palpitations, a sensation of a racing heart, dizziness, and chest discomfort.Causes and Risk Factors: Common causes include physical exertion, emotional...
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Desensitization and Tachyphylaxis01:20

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Tachyphylaxis is described as a rapid decrease in response to a drug after repeated or continuous administration of the same drug dose. It is a phenomenon where the body becomes less responsive to a particular substance or intervention over time, requiring higher doses or stronger interventions to achieve the same effect. It results from adaptive changes in the body's receptors, signaling pathways, or physiological processes that occur in response to prolonged exposure to a stimulus.
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Heart Failure Drugs: Inotropic Agents01:26

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Positive inotropic agents are commonly used as the first line of treatment for heart failure. One such agent is digoxin, derived from the genus Digitalis, which has been known for centuries but effectively utilized since 1785. However, these cardiac glycosides can have potentially toxic effects due to their mechanism of action, which involves inhibiting Na+/K+-ATPase and increasing contractility. Digoxin is absorbed orally and distributed in various tissues, including the CNS. It has a long...
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ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias01:25

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Arrhythmia is a condition characterized by an irregular heart rhythm, with ECG changes that differ based on its origin and nature. The types of arrhythmias discussed below include atrial, junctional, and ventricular arrhythmias.Atrial ArrhythmiasPremature Atrial Complexes (PACs): PACs are early atrial beats caused by stress, caffeine, alcohol, electrolyte imbalances, hypoxia, hyperthyroidism, or certain medications (e.g., bronchodilators and decongestants). The ECG shows early P waves with an...
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Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers01:22

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Class I antiarrhythmic drugs are used to treat various types of arrhythmias or irregular heart rhythms. These drugs block the sodium (Na+) channels in the cardiac cells, thereby affecting the movement of electrical impulses across the heart. Class I antiarrhythmic drugs are divided into three subgroups: Class IA, Class IB, and Class IC, each with distinct mechanisms of action and effects on the heart.
Class 1A Antiarrhythmic Drugs: These drugs work by moderately blocking sodium channels,...
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Refractory Torsades de Pointes Due to Dofetilide Overdose.

James Crosby1, Huzefa Bhopalwala1, Amrin Kharawala2

  • 1Appalachian Regional Healthcare, Whitesburg, KY, USA.

Journal of Investigative Medicine High Impact Case Reports
|December 13, 2021
PubMed
Summary

Dofetilide overdose, though rare, can cause prolonged Torsades de Pointes (TdP) requiring extensive interventions. This case highlights the need for advanced treatment strategies beyond standard guidelines for refractory TdP from dofetilide toxicity.

Keywords:
dofetilideoverdosetorsades de pointesventricular arrhythmia

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Area of Science:

  • Cardiology
  • Clinical Pharmacology

Background:

  • Dofetilide is a Class III antiarrhythmic used for cardiac arrhythmias.
  • Antiarrhythmic drugs, including dofetilide, can prolong the QT interval, leading to bradycardia and Torsades de Pointes (TdP).

Observation:

  • A rare case of intentional dofetilide overdose in a patient with multiple comorbidities is presented.
  • The patient experienced refractory TdP lasting four days, necessitating extensive interventions beyond initial stabilization.

Findings:

  • Both therapeutic and excessive dofetilide doses can induce TdP.
  • Standard guidelines for TdP management (magnesium, electrolyte correction) may be insufficient in severe dofetilide overdose.
  • Isoproterenol and dopamine were crucial in managing persistent TdP, serving as a bridge to overdrive pacing.

Implications:

  • This case underscores the scarcity of data on managing prolonged dofetilide overdose and refractory TdP.
  • Highlights the potential need for advanced interventions like isoproterenol and dopamine in severe cases.
  • Emphasizes the importance of continuous monitoring and tailored treatment strategies for dofetilide toxicity.