CardioBird

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A CardioBird Whitepaper for Veterinarians

For decades, the electrocardiogram (ECG) has been an indispensable tool in your practice, rightly serving as the gold standard for assessing cardiac rhythm, conduction and morphology. Yet, if you only use the ECG to look for PQRST waves and heart blocks, you are missing a wealth of data about your patient’s overall physiological state.

At CardioBird, we view the ECG not just as a cardiac report, but as a sophisticated, continuous sensor for the entire body’s Autonomic Nervous System (ANS)—the hidden wiring that controls stress, pain, and adaptation. We are committed to translating cutting-edge veterinary science into practical metrics you can use daily.

Here is a look at the advanced, non-cardiac insights we can extract from the ECG, and why they matter for every patient, from routine wellness checks to surgical monitoring.

 

1. The Autonomic Report Card: Heart Rate Variability (HRV)

Heart Rate Variability (HRV) is the measurement of the tiny fluctuations in time between consecutive heartbeats.¹  Contrary to intuition, a perfectly regular heart is not a healthy one.¹・²  A high degree of variability indicates a resilient and adaptable cardiovascular system, reflecting a strong, balanced ANS.

HRV is a proxy for the dynamic balance between the two branches of the ANS:

• Sympathetic Tone: The “fight-or-flight” response, associated with stress and fear.²
• Parasympathetic (Vagal) Tone: The “rest-and-digest” response, associated with calm and recovery.²

By analyzing HRV metrics like the Root Mean Square of Successive Differences (RMSSD) and high-frequency power, we can non-invasively quantify stress, assess recovery capacity, and gain insight into overall systemic health and welfare.

 

2. Objective Pain Assessment: The PTA Index

One of the greatest challenges in veterinary medicine is the objective assessment of pain and nociception, especially in anesthetized or non-communicative patients. This is where a specialized ECG metric, the Parasympathetic Tone Activity (PTA) Index, proves invaluable.

PTA is an advanced, continuous metric derived from HRV analysis designed to measure the analgesia/nociception balance during surgery.³

• How it works: PTA is scored between 0 and 100. High values (closer to 100) indicate strong parasympathetic tone, correlating with adequate analgesia and minimal discomfort. Conversely, a decrease in PTA signals a sympathetic surge, which is typically triggered by a painful stimulus.³
• Clinical Relevance: This index can serve as an early warning system. Studies in anesthetized dogs have shown that a decline in the dynamic PTA variation (ΔPTA) of at least −18% can predict subsequent adverse hemodynamic events (like a significant increase in heart rate or systolic blood pressure) within five minutes.³ Monitoring PTA allows you to pre-emptively adjust analgesia, greatly improving patient safety and welfare.

 

3. Deeper Diagnostics: Morphology, Respiration and Scale

Beyond the ANS, the ECG provides critical data for specialized diagnostics:

• Breed-Specific Morphology: Standard ECG components—like P wave duration, QRS complex length, and QT interval—show wide variations based on breed and size.⁴  For instance, large breeds typically have lower resting heart rates compared to smaller dogs.⁴  Interpreting an ECG accurately requires knowledge of these inherent differences, ensuring that normal breed-specific variations are not misdiagnosed as pathology.
• ECG-Derived Respiratory Rate (EDR): The heart rate naturally speeds up and slows down with the breathing cycle, a phenomenon known as Respiratory Sinus Arrhythmia.ㅊBy continuously tracking these changes in the R-R interval, we can use the ECG to non-invasively estimate the patient’s respiratory rate (EDR).⁵  This is highly useful for continuous, low-stress monitoring of respiration in awake or recovering patients.

 

CardioBird: Translating Science into Practice

The complexity of these advanced metrics—from managing short-term HRV data to interpreting breed-specific QRS norms and utilizing specialized indices like PTA—underscores why AI-ECG services are essential.

At CardioBird, our expertise lies in integrating deep physiological knowledge, ensuring every ECG processed provides the most complete, scientifically rigorous assessment possible. We are passionate about giving veterinarians the tools to move beyond basic cardiac screening and truly elevate their practice by understanding the patient’s full physiological story.

The ECG is your window into the heart and the mind. We are here to help you see it all.

 

 

References

1 Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology, “Heart rate variability: standards of measurement, physiological interpretation, and clinical use,” Circulation, vol. 93, no. 5, pp. 1043–1065, Mar. 1996.

2 Cleveland Clinic, “Heart Rate Variability (HRV),” Cleveland Clinic. [Online]. Available: https://my.clevelandclinic.org/health/symptoms/21773-heart-rate-variability-hrv.

3 J. Murrell et al., “Evaluation of the Parasympathetic Tone Activity (PTA) index to assess the analgesia/nociception balance in anaesthetised dogs,” Res Vet Sci, vol. 115, pp. 271–277, Dec. 2017.

4 A. Ghiță et al., “Analysis of electrocardiograms in different dog breeds,” Vet Med J, vol. 1, no. 1, pp. 25–34, 2024.

5 W. Karlen and C. Weber, “Evaluation of methods for estimation of respiratory frequency from the ECG,” in Annu Int Conf IEEE Eng Med Biol Soc, 2012, pp. 3842–3845