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Electrocardiogram Fundamentals

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...

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...

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

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...

Dysrhythmias V: Evaluating Dysrhythmias

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...

Electrocardiogram

Electrocardiogram

An electrocardiogram (ECG or EKG) is a critical diagnostic tool that records the electrical signals produced by the heart during each heartbeat. This recording is achieved through electrodes placed strategically on the arms, legs, and chest. The electrocardiograph amplifies these signals and produces 12 distinct tracings, offering a comprehensive understanding of the heart's electrical activity.
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and the T...

Peripheral Arterial Disease II: Clinical Manifestations and Diagnostic Evaluation

Peripheral Arterial Disease II: Clinical Manifestations and Diagnostic Evaluation

Clinical manifestationsPeripheral Arterial Disease (PAD) manifests through a range of symptoms, from the characteristic intermittent claudication to atypical presentations and severe complications in advanced stages. Intermittent claudication, a hallmark symptom of PAD, presents as exercise-induced muscle pain that typically resolves within minutes of rest. This pain is reproducible and stems from inadequate blood flow, leading to the accumulation of lactic acid produced during anaerobic...

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Updated: May 20, 2026

Electroencephalography Network Indices as Biomarkers of Upper Limb Impairment in Chronic Stroke

Electroencephalography Network Indices as Biomarkers of Upper Limb Impairment in Chronic Stroke

Published on: July 14, 2023

Two patients presenting with lower extremity paralysis and abnormal electrocardiogram.

Michael D Morgan¹, Adam Ligler, Michael D Boswell

¹Department of Internal Medicine, Carolinas Medical Center, Charlotte, NC 28232, USA.

The American Journal of Emergency Medicine

|July 17, 2012

Summary

Acute bilateral lower extremity paralysis can signal systemic disease, not just spinal cord issues. An abnormal electrocardiogram (ECG) can quickly identify metabolic or endocrine causes, guiding prompt diagnosis and treatment for this medical emergency.

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Paradigms of Lower Extremity Electrical Stimulation Training After Spinal Cord Injury

Paradigms of Lower Extremity Electrical Stimulation Training After Spinal Cord Injury

Published on: February 1, 2018

Area of Science:

Neurology
Cardiology
Endocrinology

Background:

Acute bilateral lower extremity paralysis is a critical medical emergency, often attributed to spinal cord pathology.
Systemic diseases, including metabolic and endocrine disorders, can mimic spinal cord injury, presenting as paralysis.
Early identification of systemic causes is crucial for appropriate patient management.

Observation:

Two previously healthy Hispanic men presented with sudden, severe lower extremity weakness, unable to ambulate.
Both patients exhibited abnormal electrocardiogram (ECG) findings upon initial medical evaluation.
The clinical presentation was remarkably similar in both cases.

Findings:

Abnormal ECGs served as an immediate indicator of a likely systemic etiology for the paralysis.
Diagnosis was rapidly confirmed through simple laboratory testing, revealing underlying metabolic or endocrine abnormalities.
This highlights the diagnostic value of ECG in cases of acute paralysis.

Implications:

Electrocardiogram (ECG) interpretation is vital for differentiating spinal cord pathology from systemic causes of paralysis.
Prompt diagnosis of systemic causes allows for targeted treatment, potentially preventing long-term complications.
This case series underscores the importance of a comprehensive diagnostic approach in acute paralysis.