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Related Concept Videos

ECG Interpretation of Arrhythmias I: Sinus Arrhythmias01:16

ECG Interpretation of Arrhythmias I: Sinus Arrhythmias

Arrhythmias are disturbances in the heart's rhythm that lead to abnormal heartbeats. These irregularities can originate from different parts of the heart and are classified based on their origin and nature.
Types of Arrhythmias
Sinus Node Arrhythmias
Sinus Bradycardia: Originating from the sinoatrial (SA) node, sinus bradycardia involves slower impulses, resulting in a heart rate of less than 60 beats per minute (bpm). Causes include sleep, vagal stimulation, beta-blockers, hypothyroidism, and...
Sinusoidal Sources01:18

Sinusoidal Sources

Direct current (DC) refers to an electric current that flows in a single direction, maintaining a constant polarity. This is in contrast to alternating current (AC), which periodically changes its direction and magnitude. AC forms the backbone of modern electricity transmission and distribution systems due to its efficient long-distance transmission capabilities.
In homes, the power supplies use sinusoidal sources to provide electricity. These sources generate a voltage that varies sinusoidally...
Conduction System of the Heart01:19

Conduction System of the Heart

Autorhythmicity is a term that refers to the heart's inherent ability to generate electrical signals and instigate muscle contractions. This self-regulating conduction system within the heart consists of two key components: the pacemaker cells and specialized conducting cells.
The pacemaker cells are located in two primary nodes: the sinoatrial (SA) node and the atrioventricular (AV) node. The SA node pacemaker cells can autonomously depolarize, triggering an action potential that leads to the...
Conduction System of the Heart01:20

Conduction System of the Heart

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:...
Graphical and Analytic Representation of Sinusoids01:20

Graphical and Analytic Representation of Sinusoids

Analyzing two sinusoidal voltages with equal amplitude and period but different phases on an oscilloscope, an instrument used to display and analyze waveforms, involves a three-step process.
The first step is measuring the peak-to-peak value, which is twice the amplitude of the sinusoid. This provides information about the maximum voltage swing of the waveform.
Secondly, the period and angular frequency are determined. The period is the time taken for one complete cycle of the waveform, while...
Electrophysiology of Normal Cardiac Rhythm01:19

Electrophysiology of Normal Cardiac Rhythm

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 of...

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Related Experiment Video

Updated: Jun 6, 2026

Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice
09:20

Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice

Published on: July 5, 2021

Sinus node revisited.

Dennis H Lau1, Kurt C Roberts-Thomson, Prashanthan Sanders

  • 1Cardiovascular Research Centre, Department of Cardiology, Royal Adelaide Hospital and the Discipline of Medicine, University of Adelaide, Adelaide, Australia.

Current Opinion in Cardiology
|November 25, 2010
PubMed
Summary
This summary is machine-generated.

Sinus node disease (SND) involves complex anatomy and pacemaking mechanisms. Recent research reveals multiple activation origins and highlights the "calcium clock" alongside the "membrane clock" in sinus node function and remodeling.

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High-resolution Optical Mapping of the Mouse Sino-atrial Node
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Methods for the Isolation, Culture, and Functional Characterization of Sinoatrial Node Myocytes from Adult Mice
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Methods for the Isolation, Culture, and Functional Characterization of Sinoatrial Node Myocytes from Adult Mice

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Last Updated: Jun 6, 2026

Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice
09:20

Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice

Published on: July 5, 2021

High-resolution Optical Mapping of the Mouse Sino-atrial Node
11:07

High-resolution Optical Mapping of the Mouse Sino-atrial Node

Published on: December 2, 2016

Methods for the Isolation, Culture, and Functional Characterization of Sinoatrial Node Myocytes from Adult Mice
09:32

Methods for the Isolation, Culture, and Functional Characterization of Sinoatrial Node Myocytes from Adult Mice

Published on: October 23, 2016

Area of Science:

  • Cardiology
  • Electrophysiology
  • Molecular Biology

Background:

  • Sinus node disease (SND) is a prevalent condition and the primary reason for permanent pacemaker implantation.
  • Understanding sinus node anatomy and its pacemaking mechanisms is crucial for managing SND.

Purpose of the Study:

  • To review the intricate anatomy of the sinus node.
  • To discuss the evolving comprehension of sinus node pacemaking mechanisms.
  • To examine atrial myopathy and sinus node remodeling in SND.

Main Methods:

  • High-density noncontact mapping of the human sinus node.
  • Review of recent molecular and cellular research on sinus node function.

Main Results:

  • High-density mapping revealed multiple sinus activation origins and exit sites with preferential conduction pathways.
  • A newly identified paranodal area with mixed cell types may explain discrepancies between anatomical and functional sinus node descriptions.
  • Both the 'membrane clock' (I(f)) and the 'calcium clock' are vital for sinus node automaticity.
  • Molecular links to sinus node remodeling include connexin-43 changes in aging, altered I(f) in heart failure, and calcium clock dysfunction in atrial fibrillation.

Conclusions:

  • Current research, utilizing advanced technologies, continues to refine our understanding of the sinus node, challenging century-old concepts.
  • New insights into sinus node physiology and pathology are emerging, impacting the management of SND.