Study examines link between heart rate, onset of illness

Researchers look for meaning in the milliseconds between heart beats

CALGARY – In a North American first, researchers at Rockyview General Hospital are using technology that tracks minute changes in heart rate to predict health outcomes in patients and indicate overall health and wellness.

Heart rate variability (HRV) is an indicator of stress response in the body and can act as an early warning sign for the onset of illness. Using small portable monitors, the study looks at the effectiveness of monitoring HRV to predict the onset of illness in intensive care unit (ICU) patients where medical conditions can change quickly.

“If you’re stressed, your HRV decreases, so the body’s system becomes less able to respond to ongoing and increasing stress. If you’re well, your HRV increases. These small fluctuations in heart rate can be used as an indicator for onset of a variety of condition such as cardiovascular disease, stroke, diabetes or sepsis,” says Dr. David Liepert, an Alberta Health Services (AHS) anesthesiologist and lead investigator in the study.

“Understanding how HRV can be used at the early onset of illness may eventually have wider application for the general public or healthy people who simply want to track their overall health and wellness.”

HRV has also been used in fetal heart monitors for a half century to monitor health. Dr. Liepert says decreased HRV is a proven early warning sign for illness, but his study takes a closer look at whether HRV is useful in a clinical setting, such as an ICU.

The majority of devices that claim to measure heart rate only sample heart rate at intervals, and then produce an average over time. As a result, Dr. Liepert says most mobile heart rate monitors are extremely inaccurate with a margin of error of up to 40 per cent. To accurately measure HRV, he says an electrocardiogram (ECG) is required because this technology is capable of measuring milliseconds between heart beats.

“We need to know a person’s heart rate at every moment to get an accurate picture. It’s those miniscule shifts where the real information lies,” Dr. Liepert says. “But getting this level of detail has historically required large and often expensive pieces of technology.”

Dr. Liepert and his team are using a small mobile device developed by the medical technology firm Biotricity (BTCY) that tracks HRV accurately. The small black oval-shaped device – about two by four inches – is attached to the neck or chest of study participants and gathers information only by contacting the skin and does not require electrodes or adhesive patches. The device communicates wirelessly with a computer that processes heart rate information.

Participants wear the device day or night, as much as is convenient.

The four-month study, which wraps up next month, is made possible by a grant from the National Research Council of Canada. It will track HRV and health outcomes in 20 healthy people and 40 intensive care unit patients.

Dr. Liepert says this initial study will lead to larger-scale studies in the future.

“I decided to participate in the study because it was a unique opportunity to look at how healthy I actually am,” says Anthony Cook, one of the 20 healthy participants in the study.

“I like to consider myself a healthy guy but using this heart rate variability device will provide the data to prove it.”

“Our hospital supports any work that improves patient outcomes, safety and efficiency,” says Dr. Kelley deSouza, Medical Director of Rockyview General Hospital. “This is just one more example of the world-class research happening at Rockyview.”

Alberta Health Services is the provincial health authority responsible for planning and delivering health supports and services for more than four million adults and children living in Alberta. Its mission is to provide a patient-focused, quality health system that is accessible and sustainable for all Albertans.

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