Clinical applications of heart rate variability in dogs

Abstract

Heart rate variability (HRV) reflects the balance of the autonomic nervous system (ANS). There are two key HRV parameters: high frequency (HF), which is correlated with the parasympathetic nervous system, and low frequency (LF) which is correlated with sympathetic and vagal activity. In veterinary medicine HRV has proven to be an important tool for evaluation of cardiovascular events in patients and has provided useful clinical information in about different physiological systems. Changes in HRV are influenced by several physiological systems. HRV reflects the state of both the heart and the brain. For that reason, HRV is considered a surrogate parameter of the complex interaction between the brain and the cardiovascular system. Studies of the autonomic control of kidney disease, endocrinology disorders, respiratory disorders, and immunological disorders commonly include HRV. Additionally, HRV has shown an autonomic modulation effect following clinical treatment, indicating HRV is potentially more than just an indicator to identify disturbances of the ANS. Sympathetic activation is a poor prognostic predictor. On the other hand, parasympathetic activation is a good prognostic indicator in various conditions. HRV has become a significant predictor and a popular noninvasive tool as it is easy to perform. In conclusion, HRV measurement can be an essential tool for both scientific and clinical understanding.