Arrhythmia Research



What is an Arrhythmia?
An arrhythmia occurs when the electrical impulses that coordinate heart rhythm are not working properly. This can lead to abnormal heart rhythms, causing the heart to beat too fast, too slow or irregularly. 


Why Measure Arrhythmias?

Arrhythmias occur spontaneously in normal, healthy animals at a low incidence. Many arrhythmias are not harmful and have no clinical significance; however, some may have more serious effects and lead to cardiac arrest or sudden death. Changes in the incidence rate or type of arrhythmia may indicate disease progression or treatment effect. The underlying pathophysiology of arrhythmias is complex and still not fully understood. Animal models ranging from mice to pigs are frequently used in arrhythmia research, with dogs and primates being two of the most commonly used in treatment evaluations. 


The tables below shows the most prevalent arrhythmias in the beagle dog and the cynomolgus monkey. Both the dog and the cynomolgus monkey can have prevalent occurrences of sinus rhythms to include bradycardia, tachycardia, sinus arrhythmia and premature ventricular complexes. 



Incidence/prevalence of spontaneous arrhythmia: beagle dog1

 Arrhythmia  Incidence   Found  Incidence   Rate
 Sinus rhythms
 2450  100%
 Ventricular premature complexes 
 4  0.16%
 Second degree AV block
 14
 0.57%
 Bundle branch block (right)
 1
 0.04%
 Ventricular pre-excitation and 
Wolff-Parkinson-White syndrome
 3
 0.12%




Incidence/prevalence of spontaneous arrhythmia: cynomolgus monkey1

 Arrhythmia  Incidence   Found  Incidence   Rate
 Sinus rhythms
 1563  100%
 Atrial premature complexes
 2  0.12%
 Ventricular premature complexes
 6  0.38%
 Ventricular tachycardia
 1  0.06%
 Ventricular bigeminy
 1  0.06%
 Bundle branch block (right)
 11  0.7%
 Ventricular escape rhythms
 1  0.06%


Factors that can Cause Arrhythmias
  • Cardiac diseases
  • Electrolyte imbalances
  • Cardiomyopathy
  • Injury from myocardial infarction
  • Healing post cardiac surgery
  • Smoking
  • Drug abuse
  • Stress or anxiety
  • Medications
  • Genetics




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The most common arrhythmia types1

Classification of Cardiac Arrhythmias
Normal sinus impulse formation
Normal sinus rhythm
Sinus arrhythmia
Wandering sinus pacemaker
Disturbances of sinus impulse formation
Sinus arrest/block
Sinus bradycardia
Sinus tachycardia
Disturbances of supraventricular impulse formation
Atrial premature complexes
Atrial tachycardia
Atrial flutter
Atrial fibrillation
Atrioventricular junctional rhythm
Ventricular premature complexes
Disturbances of ventricular impulse formation
Ventricular tachycardia
Ventricular asystole
Ventricular fibrillation
Sinoatrial block
Disturbances of impulse conduction
Persistent atrial standstill
Atrial standstill
Ventricular pre-excitation
First degree AV block
Second degree AV block
Complete AV block
Bundle branch block
Sick-sinus syndrome
Disturbances of both the impulse formation and impulse conduction
Ventricular pre-excitation and Wolff-Parkinson-White syndrome
Atrial premature complexes with aberrant ventricular conduction
Ventricular escape rhythms
Junctional escape rhythms
Ventricular escape rhythms




How are Arrhythmias Measured?
Arrhythmias are identified by looking at an electrocardiogram (ECG) signal and assessing the rate and regularity of the heartbeat. Typically, ECG is measured by placing two electrodes directly on the skin and reading the potential difference between them. The detected waveform features depend on the amount of cardiac tissue involved in the contraction, and well as the orientation of the electrode placement with respect to the heart. A number of different ECG lead configurations exist based on electrode location and configuration. DSI offers several technologies to record ECG,  including implantable telemetry, external telemetry or hardwired options. 



 

DSI implants are designed for monitoring and collecting data from conscious, freely moving animals.  Implants are offered in different sizes to support a variety of animal species including mice, rats, dogs and non-human primates. Several telemetry models are capable of monitoring ECG and blood pressure.

 
 

Short durations of functional endpoints are collected non-invasively from chemically or physically restrained animals that are connected to external  devices capable of monitoring surface ECG or blood pressure and recording  directly into an acquisition and analysis computer system.

 
 

ECG and blood pressure signals are collected from conscious, freely moving animals wearing a jacket which contains and protects a small JET device capable of monitoring cardiovascular data and transmitting data to an acquisition and analysis computer system.

 

1100 Arrhythmia articles citing DSI in Google Scholar





Arrhythmia Detection and Analysis

Traditional arrhythmia detection is accomplished by examining ECG waveforms to assess heart rate and rhythm. Anomalies are found by manually counting the number of normal complexes (p waves for atrial rate, QRS for ventricular) in a given time period, looking for variations in waveform morphology, and marking missing waveforms. Until recently with the release of Data Insights, previously developed software made only marginal improvements in this process.


Data Insights
Unlock the information in your data.


Data Insights™ offers an automated analysis method to accurately and consistently find, classify, and report on the arrhythmias within the ECG signal. The following table outlines the arrhythmia types, classifications, and quantification parameters available with Data Insights.

Types of Arrhythmias Classifications Reporting Parameters
Ventricular beats Runs of complexes Durations
Atrial beats Couplets Occurrences
Junctional beats Triplets Cycles per occurrence
Atrioventricular (AV) block Bigeminy Distribution
Sinus pause Trigeminy
Premature beats





 




DSI's bibliography search tool may help you find publications known to use DSI technology. It is searchable by keyword, title and author and references of interest can be easily exported. The following publications have been included as references to demonstrate how arrhythmias can be assessed and data applied to specific research applications.

References

Large Animal 

1Gauvin, D.V., Tilley, L. P., Smith, F. W. K. Jr., Theodore J. Baird. (2009). Spontaneous cardiac arrhythmias recorded in three experimentally- and drug-naive laboratory species (canine, primate, swine) during standard pre-study screening. Journal of Pharmacological and Toxicological Methods. 59(2) 57-61. doi: 10.1016/j.vascn.2008.12.001

Chui, R. W., Derakhchan, K. & Vargas, H. M. (2012). Comprehensive analysis of cardiac arrhythmias in telemetered cynomolgus monkeys over a 6 month period. Journal of Pharmacological and Toxicological Methods. 66(2):84-91. doi: 10.1016/j.vascn.2012.05.002

Cools, F., & Gallacher, D. (2009). Normal prevalence of cardiac arrhythmias in 24 h ECG recordings of chronically telemetered, healthy, freely moving beagle dogs. Journal of Pharmacological and Toxicological Methods, 60(2), 235–236. http://doi.org/10.1016/j.vascn.2009.04.112


Tilley, L. P., Smith, F. W. K., Oyama, M. A., & Sleeper, M. M. (2008). Manual of Canine and Feline Cardiology (Fourth Edition). Elsevier.




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