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ECG Interpretation of Arrhythmias I: Sinus Arrhythmias

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...

Dysrhythmias III: Characteristics of Dysrhythmias

Dysrhythmias III: Characteristics of Dysrhythmias

Dysrhythmias, also known as arrhythmias, are irregular heart rhythms that result from abnormal electrical activity in the heart, affecting its ability to circulate blood efficiently. Tachyarrhythmias, a subset of dysrhythmias, are characterized by abnormally fast heart rates exceeding 100 beats per minute. Here are some types of tachyarrhythmias with their distinct ECG features:Sinus Tachycardia:Sinus tachycardia presents a regular heart rhythm with an increased rate of 101-180 beats per minute.

Dysrhythmias IV: Characteristics of Bradyarrhythmias

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...

Disturbances in Heart Rhythm

Disturbances in Heart Rhythm

Arrhythmia or dysrhythmia refers to an abnormal heart rhythm caused by a defect in the heart's conduction system. It can cause the heart to beat irregularly, too quickly, or too slowly, leading to symptoms like chest pain, shortness of breath, and fainting. Factors such as stress, caffeine, alcohol, nicotine, cocaine, certain drugs, congenital defects, diseases, and electrolyte abnormalities can trigger arrhythmias.
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...

Dysrhythmias II: Classification of Tachyarrhythmias

Dysrhythmias II: Classification of Tachyarrhythmias

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...

Mechanism of Cardiac Arrhythmias

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.

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Related Experiment Video

Updated: Jul 13, 2026

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

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

Published on: July 5, 2021

Unusual sinus arrhythmia.

P Gratadour, A Cividjian, P Sagnard

International Journal of Cardiology

|August 21, 2007

Summary

In hypertensive patients after surgery, researchers observed unusual heart rate patterns (RR intervals) during spontaneous breathing. These heart rate variations were not directly linked to breathing cycles.

Area of Science:

Cardiology
Physiology
Critical Care Medicine

Background:

Hypertension is a significant risk factor for cardiovascular complications, especially post-surgery.
Monitoring heart rate variability (HRV) is crucial in assessing autonomic nervous system function in critical care settings.
Spontaneous ventilation is a common mode of respiratory support for post-operative patients.

Observation:

A notable juxtaposition of prolonged and shortened RR intervals was observed in two hypertensive patients.
These cardiac rhythm variations occurred during the recovery phase following major surgical procedures.
Sinus rhythm was confirmed throughout the entire observation period, ruling out arrhythmias.

Findings:

The observed oscillations in RR intervals were not directly correlated with individual respiratory cycles.

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Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection

Published on: February 17, 2015

Analyzing Long-Term Electrocardiography Recordings to Detect Arrhythmias in Mice

Analyzing Long-Term Electrocardiography Recordings to Detect Arrhythmias in Mice

Published on: May 23, 2021

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Last Updated: Jul 13, 2026

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

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Published on: July 5, 2021

Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection

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Analyzing Long-Term Electrocardiography Recordings to Detect Arrhythmias in Mice

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This suggests complex autonomic regulatory mechanisms are at play beyond simple respiratory-cardiac coupling.

The findings point to potential alterations in autonomic control in hypertensive patients post-surgery.

Implications:

Understanding these complex heart rate patterns may improve risk stratification for cardiovascular events in post-operative hypertensive patients.
Further research into the mechanisms underlying these oscillations could lead to novel therapeutic targets for managing autonomic dysfunction.
This observation highlights the need for detailed HRV analysis in specific patient populations recovering from surgery.