ISSN 2398-2942      

ECG: overview



  • An electrocardiogram (ECG), is a recording of the electrical potential generated within the heart during the cardiac cycle.
  • It is a measurement of voltage (amplitude), against time.
  • The electrical potential generated during the cardiac cycle is measured by connecting electrodes (attached to specific body sites), to a galvanometer and the changes in electrical potential with time are recorded on to graph paper.
  • The cardiac cycle is usually initiated by an electrical impulse from the sinus node and a wave of depolarization and subsequent repolarization spread throughout the cardiac myocardium.
  • The ECG machine measures the sum of this electrical activity, as detected by the surface electrodes, against time and, providing that the electrodes are placed correctly, an examination of the subsequent ECG tracing will provide useful information on cardiac structure and arrhythmias.
  • Under certain circumstances the ECG may be useful in the assessment of some electrolyte and acid-base disorders.

Connecting the ECG leads

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Interpreting the ECG

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Further Reading


Refereed papers


Anesthesia: for cardiovascular insufficiency

Anesthesia: for ruptured diaphragm

Anesthesia: for thoracic surgery

Anesthesia: in chest trauma

Anesthetic monitoring: esophageal stethoscope

Anesthetic monitoring: overview

Arthritis: borrelial

Atrioventricular valve dysplasia

Balloon valvuloplasty

Borax poisoning

Brachycephalic obstructive airway syndrome (BOAS)

Cardiotoxic plant poisoning

Cor pulmonale

ECG: ambulatory monitoring

ECG: principles of interpretation

Endocarditis: bacterial

Fluid therapy: for electrolyte abnormality

Heart: 3rd degree atrioventricular block

Heart: aortic stenosis

Heart: atrial fibrillation

Heart: atrial premature complexes

Heart: atrial septal defect

Heart: congestive heart failure

Heart: dilated cardiomyopathy (DCM)

Heart: dysrhythmia

Heart: first degree atrioventricular block

Heart: hypertrophic cardiomyopathy (HCM) and hypertrophic obstructive cardiomyopathy (HOCM)

Heart: mitral valve degenerative disease

Heart: myocarditis

Heart: pulmonic stenosis

Heart: second degree atrioventricular block

Heart: sinus block - arrest

Heart: tetralogy of fallot

Heart: tricuspid valve degenerative disease

Heart: ventricular septal defect


Kidney: acute kidney injury (AKI)

Lung: pulmonary thromboembolism

Patent ductus arteriosus

Pericardial cysts

Pericardial disease

Pericardium: constrictive disease

Pericardium: idiopathic hemorrhage

Pericardium: neoplasia (heartbase tumor)

Pre-renal azotemia

Spleen: neoplasia

Toad poisoning

Tracheostomy: temporary

Ventricular tachycardia

Vitamin D poisoning (cholecalciferol)

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