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Related Concept Videos

Conduction System of the Heart01:20

Conduction System of the Heart

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The cardiac conduction system produces and transmits electrical impulses that prompt myocardial contraction, ensuring efficient heart function. This intricate system ensures that the heart beats in a coordinated and efficient manner, beginning with the atria and then the ventricles. The conduction system optimizes cardiac output by maintaining this precise sequence, which is crucial for adequate blood circulation.
This system relies on the unique properties of nodal and Purkinje cells:...
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Electrophysiology of Normal Cardiac Rhythm01:19

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The normal cardiac rhythm is a synchronized electrical activity that facilitates the regular and coordinated contraction of the heart muscle. This process is essential for efficient blood circulation throughout the body. The fundamental elements involved in establishing and maintaining this rhythm include the unique electrical properties of cardiac muscle cells, the sinoatrial (SA) node's pacemaker function, the specialized conducting system, and the ionic mechanisms underlying each phase...
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Cardiac Action Potential01:30

Cardiac Action Potential

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Cardiac action potentials are essential for proper heart function, enabling the rhythmic contractions needed for adequate blood circulation. Nodal cells and Purkinje fibers, specialized for electrical conduction, generate these action potentials.
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
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The Cardiac Cycle01:13

The Cardiac Cycle

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The heart beats rhythmically in a sequence called the cardiac cycle—a rapid coordination of contraction (systole) and relaxation (diastole).
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Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers01:20

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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.
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GPCRs are primarily responsible for our sense of smell, taste, and vision.  The binding of a sensory stimulus activates GPCR to stimulate effector proteins, many of which are ion channels in the sensory organs. GPCRs modulate the opening and closing of the target ion channels either directly by binding them, or by releasing second messengers that activate these channels. As ions move across the membrane, the membrane potential is altered, which induces an appropriate response.
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Related Experiment Video

Updated: May 26, 2025

Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice
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HCN4 in the atrioventricular node.

Jaël S Copier1, Arie O Verkerk2, Elisabeth M Lodder1

  • 1Experimental Cardiology, Amsterdam UMC, Amsterdam, The Netherlands; Heart Failure & Arrhythmias, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands.

Heart Rhythm
|February 23, 2025
PubMed
Summary
This summary is machine-generated.

Hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) is crucial for heart rhythm. This review highlights HCN4's significant, yet understudied, role in the atrioventricular node (AVN) and its implications for heart conditions.

Keywords:
Atrioventricular node (AVN)HCN4I(f)IvabradineSinoatrial node (SAN)

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Area of Science:

  • Cardiology
  • Molecular Biology
  • Electrophysiology

Background:

  • The funny current, driven by Hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4), is vital for cardiac pacemaker function.
  • While HCN4's role in the sinoatrial node is established, its function in the atrioventricular node (AVN) remains less understood.
  • HCN4 is expressed throughout the AVN across mammalian species, suggesting conserved importance.

Purpose of the Study:

  • To review and summarize current findings on HCN4's role in the atrioventricular node (AVN).
  • To explore the regulators and pathological implications of HCN4 in the AVN.
  • To highlight the significance of HCN4 for normal and abnormal AVN function.

Main Methods:

  • Review of existing literature on HCN4 expression, regulation, and function in the AVN.
  • Analysis of data from knockout/knockin mouse models and clinical studies.
  • Examination of the effects of HCN4 modulators like ivabradine.

Main Results:

  • HCN4 expression is consistent in the AVN across species.
  • AVN-specific HCN4 dysfunction in animal models leads to reduced funny current and AV block.
  • HCN4 expression changes are linked to aging, disease states, and altered cardiac conduction parameters (e.g., PR interval).

Conclusions:

  • HCN4 plays a critical role in AVN function, impacting cardiac rhythm regulation.
  • Dysregulation of HCN4 in the AVN contributes to various cardiac conduction abnormalities and heart diseases.
  • Further research into HCN4's AVN-specific mechanisms is essential for understanding and treating cardiac arrhythmias.