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Related Concept Videos

Electrocardiogram Fundamentals01:28

Electrocardiogram Fundamentals

Introduction
An electrocardiogram (ECG) is a diagnostic tool for identifying cardiac conditions such as arrhythmias, conduction abnormalities, and myocardial ischemia.
Definition
An electrocardiogram (ECG) visualizes the heart's electrical activity by tracing the electrical movement associated with each heartbeat on a graph or monitor. As the heart beats, an electrical wave passes through it, correlating with the cardiac cycle events.
Parts of an ECG
An ECG utilizes electrodes on the skin to...
Dysrhythmias V: Evaluating Dysrhythmias01:30

Dysrhythmias V: Evaluating Dysrhythmias

Dysrhythmias, also known as arrhythmias, are disturbances in the heart's rhythm that range from benign to life-threatening. A thorough evaluation is crucial for appropriate management and involves a comprehensive medical history, physical examination, and various diagnostic tests.Medical HistorySymptoms: Collect detailed information on palpitations, dizziness, syncope, chest pain, and fatigue. Note their onset, frequency, and triggers.Previous Cardiac Issues: Document any history of heart...
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...
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...
Dysrhythmias I: Introduction01:15

Dysrhythmias I: Introduction

Dysrhythmias refers to abnormalities in the heart's rhythm. They result from disruptions in the heart's electrical conduction system, which includes the sinoatrial(SA)node, atrioventricular(AV) node, the bundle of His, bundle branches, and Purkinje fibers.Definition and PathophysiologyDysrhythmias result from disorders of impulse formation, impulse conduction, or both. The heart contains specialized cells in the sinoatrial node, atrioventricular node, and the bundle of His and Purkinje fibers...
Dysrhythmias II: Classification of Tachyarrhythmias01:28

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...

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Electrocardiogram Recordings in Anesthetized Mice using Lead II
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Electrocardiogram Recordings in Anesthetized Mice using Lead II

Published on: June 20, 2020

Limb lead interchange in thorough QT/QTc studies.

Vaibhav Salvi1, Dilip R Karnad, Gopi Krishna Panicker

  • 1Quintiles Cardiac Safety Services, 502 A, Leela Business Park, M.V. Road, Andheri (East), Mumbai 400 059, India. vaibhav.salvi@quintiles.com

Journal of Clinical Pharmacology
|January 7, 2011
PubMed
Summary

Electrocardiogram (ECG) limb lead interchanges occurred in 17.9% of subjects, more often with Holter devices. Quality control is crucial for accurate QT interval measurements and diagnosis.

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Area of Science:

  • Cardiology
  • Medical Device Technology
  • Clinical Diagnostics

Background:

  • Electrocardiograms (ECGs) are vital for cardiac assessment.
  • Limb lead interchanges are a known source of ECG artifact.
  • Thorough QT/QTc studies require high-fidelity ECG data.

Purpose of the Study:

  • To quantify the incidence and types of inadvertent limb lead interchanges in clinical studies.
  • To evaluate the effectiveness of different methods in identifying these interchanges.
  • To assess the impact of limb lead interchanges on QT interval measurement and diagnosis.

Main Methods:

  • Analysis of 85,133 ECGs from 484 subjects across 5 thorough QT/QTc studies.
  • Utilized a dedicated quality control process in a central ECG laboratory.
  • Compared identification rates between ECG devices, experienced readers, and quality control.

Main Results:

  • Limb lead interchanges were found in 3.4% of ECGs (17.9% of subjects).
  • Holter devices showed significantly higher interchange rates (7.5%) than 12-lead ECGs (0.8%).
  • Experienced readers identified 79% of interchanges, with 21% detected solely by quality control.

Conclusions:

  • Limb lead interchanges are a common issue in ECG acquisition, particularly with Holter monitors.
  • Dedicated quality control processes are essential for accurate ECG interpretation.
  • Undiagnosed interchanges can lead to erroneous QT interval measurements and misdiagnosis.