Electrocardiogram (ECG) is a rapid, non-invasive and safe cardiac assessment to detect and record changes in electrical activities of the heart. ECG is the gold standard for detecting heart rate, rhythm, conduction and possible arrhythmia. It also provides information on chamber enlargement. It is a fundament test in veterinary medicine that worth more attention.
Clinical applications of ECG – Diagnosis and recording of problematic arrhythmias
Arrhythmia shall be diagnosed through ECG. Although it is possible to detect arrhythmia during auscultation, ECG remains the golden standard for diagnosis. Detail recording of the rhythmic electrical activities are needed to make confirmative diagnosis. Therefore, ECG remains the gold standard for arrhythmia detection. Please find below scenarios related to arrhythmia commonly seen in daily practice:
ECG should be performed when arrhythmia is detected during physical examinations to distinguish different possible conditions, including bradycardia, tachycardia, arrhythmia in sinus or non-sinus nature.
Pets with a medical history of syncope, episodic muscle weakness, exercise intolerance and other clinical signs, may come with transient arrhythmia. Other than standard ECG, long-term monitoring using Holter or cardiac event recorder is needed to distinguish and rule out whether it is a temporary or a persistent arrhythmia.
Effective evaluation is needed for the treatment of arrhythmia and/or heart disease and its possible adjustment. It is noteworthy that medications (such as digoxin, pimobendan) used to treat related conditions may induce and increasse the chance of arrhythmia.
Pets suffering from systemic diseases may experience significant life-threatening arrhythmia under some conditions such as electrolyte imbalance (hyperkalemia, hyponatremia, hypercalcemia, hypocalcemia ), tumours (especially splenic tumours), gastric dilatation torsion (GDV) and sepsis etc. There is a need for ECG test in these cases to confirm the diagnosis of arrhythmia.
Beyond arrhythmia – Other applications of ECG
ECG provides also information about heart chamber size. Despite being less sensitive than cardiac imaging examinations for chamber enlargement detection, changes of the ECG wave pattern provide indirect evidence of chamber enlargement with high specificity. There is also literature mentioning specific ECG changes related to mitral valve disease. As the heart disease condition worsens, changes in ECG waveform provide evidence-based reference to veterinarians for effective disease treatment and tracking.
Other ECG findings that provide veterinarians insights for further investigations and diagnosis including (1) pericardial effusion caused by the potential ECG alternation and QRS amplitude reduction, (2) abnormal ECG caused by hypothyroidism or hyperthyroidism, and (3) changes in the ECG parameters caused by stimulation of the vagus nerve.
Different types of ECG
There is more than one type of ECG machine. Each type of ECG machine has its own application and cannot be replaced by one and the other. The following is a brief introduction to different types of ECG and their applications:
Single-lead ECG: Lead II is commonly used to obtain standard rhythm and PQRS waveforms information for single lead measurement. Most ECG findings could be obtained easily and quickly with minimal stress for the pet patient. Single-lead is suitable for initial assessment and under single lead measurement, it provides evidence for subsequent treatment or further investigations. CardioBird is the common choice for single-lead ECG on the market. Supported by both cardiologist team and proprietary AI technology, CardioBird empowers primary care veterinarians to offer initial cardiac assessment breaking through the barriers of time and resources. CardioBird is a helpful tool for veterinarians to perform pets’ initial cardiac assessment!
be used as a reference for subsequent treatment or further investigations. At present, CardioBird is a common single-lead ECG product available on the market. Supported by the cardiologist team and proprietary AI technology, CardioBird empowers the primary care veterinarians to break through the barriers: time and resources.
Diagnostic electrocardiogram (ECG): Standard diagnostic ECG usually goes with six or twelve leads, simultaneously records the electrical activity of the heart from different axis for advanced diagnosis. It usually requires a longer operation and interpretation time. There are different brands of diagnostic ECG on the market, which are suitable for further investigations and comprehensive evaluation.
Holter (Continuous ECG): It records ECG activities continuously for 24 hours to 48 hours. It could better determine the severity and clinical relevance a transient arrhythmia. However, the process could be complicated due to the specific setup and cooperation of the patient and the monitoring and interpretation required. Therefore, such service is rarely provided at primary care setting. It is recommended to refer the case to the Cardiology clinics or University Medical Center.
Common arrhythmia in dogs and cats – By Clinician’s Brief
Further reading – How can AI help veterinarians break through limitations on cardiac assessments for pets?
Rapid Cardiac Assessment at Primary Care – Sharing by Internal medicine veterinarian Dr. I-Ju Ho