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相关概念视频

Mechanism of Cardiac Arrhythmias01:28

Mechanism of Cardiac Arrhythmias

Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.
Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers01:22

Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers

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

Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers

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 the heart's...
Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers01:20

Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers

Class IV antiarrhythmic drugs, such as verapamil and diltiazem, block calcium channels. They primarily affect the heart, slowing the conduction in calcium-dependent tissues like the SA and AV nodes. These drugs manage reentrant supraventricular tachycardia (SVT) and reduce ventricular rate in atrial flutter/fibrillation.
Verapamil, a calcium channel blocker, inhibits calcium movement across myocardial cell membranes and vascular smooth muscle. This results in the dilation of coronary and...
Dysrhythmias IV: Characteristics of Bradyarrhythmias01:18

Dysrhythmias IV: Characteristics of Bradyarrhythmias

Bradyarrhythmias are cardiac rhythm disorders characterized by a slower-than-normal heart rate, typically defined as fewer than 60 beats per minute. Some of which are discussed here:Sinus BradycardiaSinus bradycardia presents a heart rate lower than 60 beats per minute, with a regular rhythm originating from the SA node. The ECG typically shows normal P waves preceding each QRS complex, a normal PR interval (0.12 to 0.20 seconds), and a normal QRS duration (0.06 to 0.10 seconds).First-Degree AV...
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias01:25

ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias

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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Updated: Jul 20, 2026

Electrocardiogram Recordings in Anesthetized Mice using Lead II
04:16

Electrocardiogram Recordings in Anesthetized Mice using Lead II

Published on: June 20, 2020

慢性阿米奥达龙在获得长QT综合征的动物模型中,尽管QT延长,但没有引起torsade de pointes心律失常.

J M van Opstal1, M Schoenmakers, S C Verduyn

  • 1Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht, the Netherlands. m.vos@cardio.azm.nl

Circulation
|November 28, 2001
PubMed
概括

阿米奥达龙和德龙达龙可以延长QT时间. 与阿米奥达龙不同,dronedarone增加了Torsade de Pointes (TdP) 风险,这是由于增加了QT分散和早期的脱极化,而不是amiodarone.

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科学领域:

  • 药理学 药理学是指药理学的学科.
  • 心脏病学 心脏病学
  • 电力生理学 电力生理学

背景情况:

  • 阿米奥达龙是一种有效的抗失律药物,具有罕见的Torsade de Pointes (TdP) 风险.
  • 无胺的类似物dronedarone是为了减轻amiodarone的不良影响而开发的.
  • 这项研究比较了amiodarone和dronedarone的电生理学和前节律特性.

研究的目的:

  • 为了比较amiodarone和dronedarone的前节律潜力.
  • 在狗模型中评估QT间隔,动作潜能持续时间 (APD) 和TdP的影响.
  • 评估这些药物对APD (DeltaAPD) 和早期脱极化后 (EAD) 的腹腔间分散的影响.

主要方法:

  • 使用了一种患有慢性完全心房阻塞 (CAVB) 和获得长QT综合征的狗模型.
  • 口服阿米奥达龙或无人机阿米奥达龙4周.
  • 记录了表面ECG和心室单相作用潜力,以测量QTc,APD,DeltaAPD,EAD和TdP.

主要成果:

  • 艾米奥达龙和德龙达龙都延长了QTc间隔.
  • 德罗纳达龙显著增加了DeltaAPD和TdP发病率 (4/8狗),与阿米奥达龙 (0/7狗) 不同.
  • 与amiodarone相比,dronedarone还显示了EAD和心室外宫跳动的更高发病率.

结论:

  • 这两种药物都通过延长QT间隔来表现出III类抗失律作用.
  • 在这个模型中,阿米奥达龙缺乏TdP,这归因于同质的APD延长和没有EAD/异胎节拍.
  • 在CAVB狗模型中,Dronedarone显示出更高的前节律失常风险,与增加的DeltaAPD和EADs有关.