Tracking heart health with wearable devices

Tim Hin Wai Lui, 12 Jul 2017

The world’s population is ageing faster than ever before. Several favourable advancements over previous decades in public health, medical technologies and living conditions, have improved the health and longevity of millions. And as life expectancy is increasing, birth rates are declining because of improved access to family planning, education and employment[1].

With current trends, it is predicted that by 2030, 1 in 6 people will be over the age of 60 and by 2050 this statistic will change to 1 in 5 people[1]. From 2015 to 2030, the older population is projected to increase 56 per cent, from 901 million to 1.4 billion people[2].

Such shifts in demographics and environments have transformed health challenges significantly, from nutritional deficits or infectious diseases such as influenza to diseases classified as degenerative, such as cardiovascular disease. Urbanisation is another force that has contributed to the change in disease types by altering the way we live[3]. Moving from rural communities to compact cities has reduced physical activity and excessive consumption of processed foods, both of which are risk factors for cardiovascular disease. The health effects of urbanisation is not only of concern among high-income countries but are also being observed in emerging and developing countries[3].

Cardiovascular disease: Consistently the highest in mortality and healthcare spending

Globally, cardiovascular disease remains the number one cause of death, killing 17.5 million people in 2012 according to the World Health Organization. Coronary heart disease and stroke are the two largest categories of disease and at least 45% are complications of hypertension[4].

High blood pressure is one of the leading risk factors for disease worldwide, having large effects on population health in all regions, including low-income regions in sub-Saharan Africa and south Asia[5]. In fact, the World Health Organization has called hypertension a worldwide epidemic, estimating that 40% of adults aged 25+ have been diagnosed with high blood pressure[6].

It follows that cardiovascular diseases make up the largest share of healthcare costs ranging from 11% to 15% of healthcare expenditure in several OECD countries.7 Cardiovascular disease consistently tops hospital spending among 11 OECD countries, with an average of 17.5% of total spend[7].

Top spending categories in hospital care by diagnostic category. Available from: http://www.oecd.org/els/health-systems/estimating-expenditure-by-disease-age-and-gender.htm

While population ageing shows no signs of slowing down, we will expect to see a rise in chronic conditions and cardiovascular disease. Public health organisations, governments and health technology industries must adapt to accommodate these growing needs and control for mounting healthcare costs.

Age of wearable health technologies

Faith in the wearable technology industry as a potential solution to mounting healthcare costs can be observed in the global healthcare sector's USD 58.9 billion investment in internet of things (IoT) devices, software, and services in 2016[8].

Technologies that allow for remote monitoring of patients could mean cost savings from reduced hospital visits, more effective and timely adjustments to treatment and increased patient engagement. The wealth of information provided on the internet and the availability of bio-sensing wearables have made it possible for patients and consumers to be more involved in self-care than ever before. People want a way to self-monitor and track progress. With wearable technology there is a shift of dependency from healthcare professionals in hospitals and clinics to the individual in the community going about daily activities in managing health.

Home blood pressure monitors are a concrete example of how technology, given to the patient to use at home can create health benefits and cost savings. The American Heart Association wrote a statement endorsing reimbursement of home blood pressure monitors as a potential way to lower healthcare costs[9]. One mechanism of cost reduction was the reduced need for office visits due to communication of blood pressure values over the phone. Self-monitoring also plays a role in reduction of blood pressure and tighter control, leading to less medication needed and thus lower costs[10]

Blood pressure: A metric still missing from health wearables

While home blood pressure monitors have been noted as an important tool to increase awareness and control of blood pressure, there are several drawbacks that limit its capabilities in these two areas.

Home blood pressure monitors are simply not designed to be portable or wearable, they only provide a moment in time blood pressure value. No information is collected about how blood pressure fluctuates during what activities and in what environments since measurements are done at home and at most twice a day.

Studies have recognised the importance of stabilising blood pressure variability - the extent to which values go up and down over a period of time. Rather than only focusing on lowering average blood pressure values, there may be more protection against heart disease in achieving hour-to-hour, day-to-day controlled BP values over time[11]

Wearables are equipped to capture these natural fluctuations of blood pressure, while users are at work or out doing daily activities. This wealth of data could help doctors make better informed decisions when it comes to treatment of hypertension. This is a surprisingly difficult challenge, given that only one third of those diagnosed with hypertension achieve blood pressure control within normal values[12]. 

Heartisans Watch, cuff-less blood pressure monitor

Heartisans’ mission is to address the disadvantages of blood pressure monitors and make it easy for anyone to track and manage blood pressure. Due to the high prevalence of hypertension worldwide and the lethal complications that result from elevated blood pressure, it is pertinent to develop innovations to combat this health epidemic.

Heartisans Watch measures blood pressure using Pulse Transit Time (PTT), a method that has been studied extensively as a non-invasive alternative to blood pressure measurement. PTT is the time between when a pulse leaves the heart and when it arrives at a peripheral part of the body. This time is correlated with a systolic and diastolic blood pressure value measured by a separate blood pressure monitor. Subsequent blood pressure measurements can be derived using this calibration point and machine learning algorithms.

The user records a one-lead ECG rhythm when a finger is placed on the sensor while wearing the watch. Each large spike on the ECG, signals a contraction of the heart – this is approximately when a pulse leaves the heart.

From there, the pulse travels down the arm until it reaches the PPG sensor, creating a peak in the PPG waveform. PTT is measured as the time between the peaks of the ECG and PPG waveform.

Heartisans Watch key features:

  • On demand blood pressure and ECG monitoring
  • Symptom log
  • Medication reminder
  • Data sharing
  • Step, distance and sleep tracking

Future: Advanced sudden cardiac arrest warning

When cardiac arrest strikes, the victim is rendered unconscious within a few seconds. Chances of survival decreases 7-10% every minute that the victim does not receive treatment (CPR or cardiac defibrillation). What if there was an advanced warning that could buy the victim crucial minutes to receive medical attention?

Heartisans has developed a machine learning algorithm that could predict the occurrence of cardiac arrest - up to 10 minutes in advance. It was developed using a pre-existing ECG database of individuals who suffered cardiac arrest. Testing the algorithm with the remainder of the cardiac arrest ECG database showed an overall accuracy of 87%. Next steps in the direction of obtaining FDA clearance for the sudden cardiac arrest (SCA) warning algorithm would be to conduct an open clinical trial with Heartisans Watch users in real-life settings. As users benefit from the blood pressure function of Heartisans Watch, concurrent data collection will help validate and refine the SCA warning algorithm, thus bringing life saving value to the users overtime.

Hypertension is a worldwide epidemic and one of the biggest contributors to heart disease and mortality. Tech industries have an opportunity to influence people’s awareness and control of high BP through development of wearable BP watches. While home BP monitors have been proven to be useful, an innovation such as Heartisans Watch could make a large contribution to hypertension awareness and management.

References

1. World Health Organization. World report on ageing and health. Geneva: World Health Organization. 2015 Dec.

2. United Nations, Department of Economic and Social Affairs, Population Division (2015). World Population Ageing 2015 (ST/ESA/SER.A/390).

3. Yusuf S, Reddy S, Ôunpuu S, Anand S. Global burden of cardiovascular diseases. Circulation. 2001 Dec 4;104(23):2855-64.

4. "Cardiovascular Diseases (CVDs)." World Health Organization, Sept. 2016. Web. 03 Feb. 2017.

5. Lim SS, Vos T, Flaxman AD, Danaei G, Shibuya K, Adair-Rohani H, AlMazroa MA, Amann M, Anderson HR, Andrews KG, Aryee M. A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010. The lancet. 2013 Jan 4;380(9859):2224-60.

6. World Health Organization (WHO. A global brief on hypertension: silent killer, global public health crisis.

7. Estimating Expenditure by Disease, Age and Gender - OECD [Internet]. Oecd.org. 2016 [cited 8 February 2017]. Available from: http://www.oecd.org/els/health-systems/estimating-expenditure-by-disease-age-and-gender.htm

8. 2016 Global health care outlook Battling costs while improving care [Internet]. Deloitte United States. 2016 [cited 8 February 2017]. Available from: www2.deloitte.com/content/dam/../gx-lshc-2016-health-care-outlook.pdf

9. Pickering TG, Miller NH, Ogedegbe G, Krakoff LR, Artinian NT, Goff D. Call to action on use and reimbursement for home blood pressure monitoring. Hypertension. 2008 Jul 1;52(1):10-29.

10. Staessen JA, Den Hond E, Celis H, Fagard R, Keary L, Vandenhoven G, O'brien ET, Treatment of Hypertension Based on Home or Office Blood Pressure (THOP) Trial Investigators. Antihypertensive treatment based on blood pressure measurement at home or in the physician's office: a randomized controlled trial. Jama. 2004 Feb 25;291(8):955-64.

11. Parati G, Ochoa JE, Lombardi C, Bilo G. Assessment and management of blood-pressure variability. Nature Reviews Cardiology. 2013 Mar 1;10(3):143-55.

12. Chow CK, Teo KK, Rangarajan S, Islam S, Gupta R, Avezum A, Bahonar A, Chifamba J, Dagenais G, Diaz R, Kazmi K. Prevalence, awareness, treatment, and control of hypertension in rural and urban communities in high-, middle-, and low-income countries. Jama. 2013 Sep 4;310(9):959-68.

Author

Tim Hin Wai Lui

Co-Founder, Heartisans

Tim Lui has a background in machine learning and bioinformatics. He co-founded Heartisans with the aim of helping heart disease and hypertension patients to improve their heart health. He is currently developing the Heartisans Solace, a smartwatch to accurately measure blood pressure and electrocardiogram, at the convenience of the wrist.

Heartisans Solace measures Blood Pressure by measuring Pulse Transit Time. Unlike cuff-based monitors that squeeze the arm, Heartisans Solace will give users complete freedom and comfort to measure blood pressure on the spot, at any moment.

With the accurate heart data captured and machine learning algorithm, Heartisans' smartwatch is aiming to capture coronary events early on, such as myocardia infarction and cardiac arrest.

Tim Hin Wai Lui was a speaker at the "Health monitoring: Making sense of sensors" conference at the Swiss Re Institute's Centre for Global Dialogue.

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