Acquisition
and analysis of cardiovascular signals on
smartphones:
potential, pitfalls
and
perspectives
Nico
Bruining
1,
Enrico Caiani
2,
Catherine Chronaki
3,
Przemyslaw Guzik
4and
Enno
van
der Velde
5Introduction and background
Mobile devices and applications (i.e. apps) entwine in our daily activities and affect the way we conduct business, form and maintain relationships, seek relaxation and entertainment, and more recently acquire information about our health. Smartphones are continuously develop-ing devices equipped with powerful processors, consider-able memory, touch screen, built-in wireless connectivity (e-mail, Internet access), geolocalisation (i.e. location, accelerometer, and compass) and a variety of other sen-sors. With their ability to interface peripheral devices, smartphones frequently serve as a personal hubs.
Mobile health apps, i.e. application programs offering health information and management related services
across platforms including smartphones, change the way health care is accessed, monitored, and delivered. Mobile health apps along with social media, analytics
1
Thoraxcenter, Erasmus Medical Center, the Netherlands
2
Department of Electronics, Information and Biomedical Engineering, Politecnico di Milano, Italy
3HL7 Foundation, Belgium
4Department of Cardiology-Intensive Therapy, Poznan University of
Medical Sciences, Poland
5Department of Cardiology, Leiden Medical Center, the Netherlands
Corresponding author:
Catherine Chronaki, HL7 Foundation, 38–40 Square de Meeuˆs, 1000 Brussels, Belgium.
for Big Data as well as cloud computing and storage technologies are emerging as a critical aspect of a new health economy centred on the consumer, transparency, convenience, and prevention.1 It is projected that by 2017, half of the 3.4 billion smartphone users worldwide will be using mobile health apps.2Currently, with nearly 100,000 mobile health apps in 62 appstores and an increasing number of medical sensors and peripherals, a future of mobile health is unavoidable.3,4
In clinical practice, acquisition and analysis of vital signs is crucial. Heart or pulse rate, arterial blood pres-sure, respiratory rate, body temperature, blood oxygen saturation (SpO2), and blood glucose concentration are classic examples of signals acquired from patients when admitted to the emergency room or to the outpatient clinic during regular follow-ups by health professionals. Recently however, using a smartphone, patients or their caregivers can acquire these signals anytime and any-where, more often passively without manual input of the measured values.5,6
Patients that rely on their smartphone for daily activities will soon trust apps for assessing health risks or deciding whether they need to visit a health professional. Almost half the patients or caregivers who responded to a 2014 survey were likely or some-what likely to have an electrocardiogram at home using a device attached to their smartphone and have the results sent to their physician (43.6%), or have a pace-maker or defibrillator checked at home wirelessly by their physician (42.6%). Slightly fewer would have a doctor’s appointment with a smartphone app (38.6%) or would use a lifestyle app recommended by their doctor (34%).1One of the problems is that the extent to which health apps are reliable or safe is unclear. Extensive validation data for each app are frequently unavailable, highlighting the need for formal valid-ation, consumer guidance, and regulatory oversight.
The next section presents smartphone related tech-nology solutions for the acquisition and analysis of heart or pulse rate, electrocardiogram (ECG), blood pressure and SpO2, along with validation data, when available. The discussion reflects at the potential, the pitfalls and the different perspectives underpinning the phenomenal innovations that disrupt healthcare sys-tems worldwide.
Acquisition and analysis of cardiovascular
signals on smartphones
Heart rate or pulse rate
Several smartphone apps for non-clinical use, such as fitness or life-logging,7 are available to measure the heart or pulse rate (see Table 1). These apps acquire video images obtained by the smartphone camera and
process them to derive the pulsation of the skin capillary blood flow in the fingertips as the skin is illuminated by ambient light or by light from the camera flash, while the camera is recording the image.8,9However, several major limitations can affect this approach: ambient light, white flash heating, frequency resolution of the camera, motion artefacts, sweating, cold fingers with constricted capillaries, arrhythmia with low or variable stroke volume (see Figure 1), and undetectable pulse. Whereas validation studies are relevant to specific apps and phone models, their results should not be automat-ically extrapolated to other mobile devices and applica-tions: even the same app installed on a different smartphone could show different results, due to the dif-ferent hardware specifications.
Other limitations are reliability for different heart rate ranges and reproducibility of measurements, par-ticularly in a real-life (i.e. not in the laboratory) envir-onment. Recently, a new smartphone from Samsung, i.e. Galaxy S5, has incorporated a dedicated infrared light emitting diode to improve heart rate detection in an effort to overcome some of these limitations.
Some validation studies relevant to this kind of applications are present in literature:
1. Losa-Inglesias et al.10compared the accuracy of the Heart Rate Plus app for the Samsung Galaxy Note in 46 healthy volunteers, with both palpation of the radial artery and a low-cost portable finger pulse oxim-eter. Although they demonstrated high reliability (intraclass correlation (ICC)>0.93) and consistency between the studied approaches with respect to heart rate, the results were comparable but not identical. 2. Ho Chi-Lin et al.11measured pulse rates at the finger/
toe and earlobe in 40 small children using four free smartphone apps on an iPhone 4 S, and compared those to the baseline heart rate measured by ECG monitors. The accuracy rates of the best performing app in the finger/toe group was significantly lower than that in the earlobe when the heart rate was 120 bpm (29.4 vs 76.5%), while minor differences were found for heart rates <120 bpm (60.9 vs 91.3%). 3. Wackel et al.12studied 26 paediatric patients undergo-ing an electrophysiology study, with heart rates mea-sured at baseline and during sustained ventricular tachycardia (SVT) using two apps (Instant Heart Rate and Heart Beat Rate). At baseline, the heart rate was correctly estimated within a 4 bpm range (r ¼ 0.99). However, during SVT (>200 bpm) perform-ance decreased significantly, concluding that the tested apps should not be considered a reliable tool for assess-ing the heart rate of children durassess-ing tachycardia. 4. McManus et al.13 tested the hypothesis that camera
pulsometry (iPhone 4 S) could detect an irregular pulse from atrial fibrillation (AF). However, the
T able 1. A non-exclusive list of smart phone apps measuring heart rate (HR). Name Platform Functionality Pr ocessing method Cost Downloads Rate Last update EasyPulse (heartbeat estimate) Andr oid, iOS HR T ap your rh ythm Fr ee N/A 3.7/5 24 Jan 2014 Pulse Calculator Andr oid HR T ap your rh ythm Fr ee 1000–5000 3.2/5 9 Jul 2013 T ap the Pulse iOS, iPad HR T ap your rh ythm Fr ee N/A – 5 Dec 2013 Sk eeper Heart Rate Andr oid HR, real-time spectr ogram Thoracic audio signal 3.44 E 500–1000 3.9/5 23 Dec 2013 Thinklabs Stethoscope App iOS, iPad HR, real-time spectr ogram Mic audio signal 3.59 E N/A – 11 Apr 2013 Rile vator e Fr equenza Car diaco Andr oid HR Finger video Fr ee 500,000–1,000,000 3/5 8 Jul 2013 Heart Rate Plus Andr oid HR Finger video Fr ee 10,000–50,000 4/5 20 Jul 2014 Instant Heart Rate Andr oid, iOS HR Finger video Fr ee 100,000–500,000 4.3/5 12 Mar 2012 Pr ecise Heart Rate Andr oid HR Finger video Fr ee 100,000–500,000 3.8/5 6 Jul 2013 Acc . Heart Beat Monitor (BPM) Andr oid HR Finger video Fr ee 10,000–50,000 3.8/5 10 Feb 2014 Quick Heart Rate Check Andr oid HR Finger video Fr ee 1000–5000 3.5/5 7 Dec 2013 Heart Rate Monitor Andr oid HR Finger video Fr ee 100,000–500,000 3.6/5 5 Jun 2014 Heart Beat Rate Andr oid HR Finger video Fr ee 100,000–500,000 4.3/5 13 Dec 2013 Real Heart Rate Calc. Andr oid HR Finger video Fr ee 100–500 4.2/5 1 Apr 2014 Runtastic Heart Rate Andr oid HR Finger video Fr ee 1,000,000–5,000,000 4.4/5 29 Nov 2013 m yPulse Lite-Instant Heart Rate Monitor iOS HR Finger video Fr ee N/A – 16 Dec 2013 Quick Heart Rate Monitor Pr o Andr oid HR finger video 0.68 E 10–50 4/5 13 Feb 2014 Rapid Heart Rate Andr oid HR finger video 0.73 E 10–50 5/5 26 Apr 2014 AF Detect Andr oid, iOS HR and Atrial Fibrillation finger video 1.49 E 1000–5000 3.7/5 27 Feb 2014 Heart Rate Monitor BPM iOS HR finger video 0.89 E N/A – 26 Dec 2013 Instant Heart Rate – Pr o Andr oid HR finger video 1.56 E 100,000–500,000 4.4/5 26 Jan 2014 Heart Rate þ Car dior espirator y Cohere nce iOS HR þ br eathing coher ence finger video 4.99$ N/A 4.5/5 22 Jun 2014 Car diografo – Car diograph iOS, Andr oid HR finger video $1.99 10,000,000–50,000,000 4/4 4 Jun 2014 Plus Sports’ Heart Rate Monitor iOS, iPad HR finger or facial video $1.99 N/A 3.5/4 9 Jul 2014 Car dio-Heart Rate Monitor , 7 minute W ork out, Calories iOS, iPad HR facial video fr ee N/A 4.5/5 2 Jun 2014 Fr equenza car diaca Cam iOS, iPad HR facial video 1.79 E N/A – 5 Sep 2012
tests were performed under controlled conditions, in 76 patients with persistent AF who were studied before and after cardioversion and showed an accur-ate discrimination (96.1% sensitivity, 97.5% specifi-city) between AF and sinus rhythm, but did not allow any conclusion about more general prospect-ive applications.
ECG monitoring
The use of a smartphones as ECG monitors (Class II medical device), with a special smartphone case or
smartphone-connected electrodes allows patients to acquire, display and transmit their ECG to medical professionals. This technology can be adopted by patients with arrhythmia, palpitations, and recurrent syncope or under specific pharmacological treatment for either diagnostic or monitoring purposes. Healthy individuals can also purchase such devices over-the-counter (OTC). ECG readings are stored in the smartphone and on secure servers in the cloud, and analysed by a qualified expert.
Most mobile ECG monitors record only single-channel ECG signal and thus their use is limited mainly to measuring heart rate and rhythm. Their use (a) (b) ECG ECG BP BP
Figure 1. Two examples of arrhythmias which may be accompanied by pulse deficit, i.e. the difference in the heart rate (on a single-channel electrocardiogram (ECG)) and pulse rate (simultaneously recorded finger pressure waveform – blood pressure (BP)). Panel (a): patient with atrial fibrillation. Panel (b): individual with sinus rhythm and single, premature ventricular beats. Arrows between ECG and BP show how each QRS complex is followed by a single pressure waveform, except in few beats (marked as X) in which the electrical activity is not accompanied by a significant haemodynamic effect, resulting in a number of heart beats higher than the number of pulse waves.
BP: blood pressure; ECG: electrocardiogram.
Table 2. Main technical characteristics of currently available electrocardiogram (ECG) monitor apps. ECG check
cardiac designs AliveCor
eMotion Mega Electronics
CardioSecur Personal MedSystems GmbH
Leads 1 1 1 12
FDA approved Yes Yes Yes On-going
Over-the-counter Yes Yes No Yes
Battery life 8 h 83 h 27 h (100 Hz) USB
Sampling rate 200 Hz 300 Hz Up to 1000 Hz 250 Hz
ECG recording length 30 s 30 s–10 min 30 s–5 d 10 s
Acquisition method Phone case
electrodesþBluetooth Phone case electrodesþ mic External electrodesþBluetooth External electrodes þ USB cable
for the diagnosis of other conditions such as myocardial ischemia or infarction is not recommended. For such a task a 12-lead mobile ECG device should be employed.14 Table 2 summarises the main technical characteristics of some available ECG monitor apps and devices.
The ECG Check monitor (Cardiac Designs, Park City, Utah, USA), cleared by the Food and Drug Administration (FDA) in February 2013, attaches to the back of the iPhone and acquires a single-channel ECG signal for 30 s using two metal electrodes, which communicate via Bluetooth with the smartphone.
The eMotion (Mega Electronics Ltd., Kuopio, Finland) device, is a Conformite´ Europe´ene (CE) marked and FDA Class II approved medical device (December 2013) that continuously transmits via Bluetooth to the smartphone a single-channel ECG obtained by an external electrode on the patient’s chest. Thirty seconds to five days of ECG recordings are uploaded to a secure server in real-time for viewing and analysis. eMotion offers a service that sends an automatic alert with the Global Positioning System (GPS) location of the patient upon arrhythmia detection.
The AliveCor (AliveCor Inc., San Francisco, California, USA) case, cleared by the FDA (for pre-scription and OTC) and CE marked, acquires short ECG rhythm strips from 30 s up to 10 min. Several val-idation studies showed that the AliveCor one-lead system (iPhone 4 S) has the same lead I QRS morph-ology as the standard 12-lead ECG, characterised by higher baseline noise.15
Smartphones applied as ECG monitor give patients the possibility of rapid cardiac monitoring from virtually anywhere to confirm an arrhythmia e.g. AF and take immediate therapeutic actions. In 204 patients, including 48 with AF, AliveCor lead I analysed by an embedded automated algorithm (iECG) detected AF with 98% sen-sitivity, 97% specificity and 97% accuracy in comparison with a standard 12-lead ECG.16In July 2014, AliveCor announced that it had acquired and reviewed 1,000,000 ECGs,17 reporting high levels of patient satisfaction.18 The iECG algorithm was also tested in 1000 pharmacy customers 65 years in whom it helped to detect new episodes of AF in 1.5% of the participants who had the CHA2DS2-VASc score 2.19 Orchard et al.20studied the feasibility of using the iECG algorithm to systematically screen patients 65 years for AF by nurses and reception-ists prior to their general practitioner consultation.
CardioSecur Active (Personal MedSystems GmbH, Berlin, Germany) is a CE marked four-electrode system for personalised 12-lead ECG on the iPhone. After 10-second acquisition it provides instant feedback for ischaemic and arrhythmia episodes based on com-parison with control readings. In 148 ECGs recorded during percutaneous coronary balloon angioplasty,
CardioSecur showed 100% agreement in
electrocardiographic localisation of myocardial ischae-mia or infarction of ST-segment changes with simultan-eously registered standard 12-lead ECG.14
In retrospect, ECG monitoring by smartphones allows to characterise heart rate and rhythm, and in some cases ischaemia/infarction ST-segment changes.
Blood pressure monitors with cuff
The gold standard for clinical blood pressure measure-ment is still the sphygmomanometer (mercury or mer-cury-free), applying the Korotkoff sound technique for determining systolic and diastolic pressure.21However, automatic blood pressure monitors are gaining popu-larity, both in the clinic and for home use. These auto-mated devices use an oscillometric technique, and algorithms derived empirically by each manufacturer.22 Home BP monitoring is recommended as an adjunct to office BP monitoring by several international guidelines for the management of hypertension, including those by the European Society of Hypertension and the European Society of Cardiology.23
There are reliable devices for measuring blood pres-sure in the home environment, for instance the BP786 (2014 Series) Wireless Upper Arm Blood Pressure Monitor – by Omron (http://omronhealthcare.com/ products/10-series-upper-arm-blood-pressure-monitor-plus-bluetooth-smart-bp786/). This device can send the measurements to a smartphone via Bluetooth.
Omron has created a dedicated website (www.
OmronWellness.com) where patients can synchronise all readings between the blood pressure monitor and smartphone for storage and analysis. Reliable (and FDA certified) blood pressure monitor systems in com-bination with a smartphone app are produced by a number of other vendors for example Withings (http:// www.withings.com) or iHealth (http://www.ihealthlabs.- com/blood-pressure-monitors/wireless-blood-pressure-monitor/). A smartphone app may also control the infla-tion and deflainfla-tion of the cuff. The smartphone version of a blood pressure monitor is thus just as reliable as a standard stand-alone digital home monitor. For this reason equivalence, the mobile version is considered a medical device that complies with European medical device regulations and is given clearance from the FDA. An important issue is the accuracy, at first use, as well as calibration on the long run. In most hospitals, the performance of electronic blood pressure monitors is periodically checked (once every one or two years). It seems therefore logical that the accuracy of a home blood pressure monitor should be also checked period-ically. Most likely, the market for mobile blood pressure monitors ‘for home use’ should not be considered or treated differently than the devices for clinical use. For many years, patients have been monitoring their blood
pressure at home and the advent of mHealth increases the potential use of such monitoring in prevention and follow-up. The British Hypertension Society24has com-piled a list with hundreds of blood pressure monitors that are validated for home use. Some of these devices have Bluetooth for communication with smartphones.
Blood pressure monitors without cuff
Besides blood pressure monitors with an arm or wrist cuff, there are also mobile solutions that work differently: blood pressure is measured without a cuff. At least two mobile devices, SOMNOtouc NIBP from Somnomedics in Germany (somnomedics.eu/products/new-somno-touch) and ViSi Mobile Monitoring System from Sotera Wireless in USA (www.soterawireless.com), reconstruct beat-to-beat blood pressure waveforms and measure arterial blood pressure without cuff. Both companies developed their own patented algorithms which are based on the continuous estimation of the pulse transit time or pulse arrival time with the use of ECG and SpO2 signals. These devices have been clinically tested.25The
SOMNOtouch NIBP (somnomedics.eu/fileadmin/
SOMNOmedics/Dokumente/BILO_Somnotouch _poster_ESH2014.pdf) has been validated by the European Society of Hypertension. The cuffless blood pressure monitor, ViSi Mobile Monitoring System, got FDA clearance for medical use in 2013.
Some other cuffless mobile solutions for blood pressure measurement that can be found in appstores are not as reliable. For example, there is a mobile app from Aura Labs Inc. which uses only the touchscreen of the smart-phone (www.instantbloodpressure.com). To measure blood pressure a thumb is placed on the screen for a few seconds. This suggests that the basic approach to meas-urement is similar to that of applanation tonometry where changes in the shape of the arterial walls are directly trans-mitted through surrounding tissues to the smartphone screen, which measures changes in the instant pressure acting on the screen. However, anecdotal experience
with this app marks it as very unreliable: the obtained readings are random, usually very low in comparison with blood pressure measurements taken by brachial blood pressure monitor and they need to be adjusted to both heart rate and gender. Others have also come to the conclusion that these apps are just for entertainment not to be recommended for medical use.26,27Similar mobile apps are neither validated nor approved by the FDA or EU.
SpO2
SpO2 is measured by pulse oximetry, a non-invasive quantification of infrared light absorption by oxyge-nated or saturated and deoxygeoxyge-nated or unsaturated haemoglobin. A conventional pulse oximeter sensor shines light beams of different wavelengths (red and infrared) through the blood that is circulating in the small skin blood vessels, for example of the finger, and detects the amount of light that is passing through. Haemoglobin with oxygen absorbs more infrared light and allows more red light to pass than haemoglobin without oxygen, which allows more infrared light to pass. The oxygen saturation is expressed as a percent-age: 100% saturation is attained when all the haemo-globin in the blood is completely saturated with oxygen (see Figure 2). To measure pulse oximetry, a special sensor is placed on a fingertip, toe tip, earlobe, and wrist or across the feet of an infant.
There is an increasing number of pulse oximetry per-ipherals, which either directly connect with a smart-phone or communicate with it via Bluetooth. Such devices are made by either professional producers of medical equipment such as Nonin (www.nonin.com), Masimo (www.masimo.com), and Contec (www.con-tecmed.com) or by companies whose main area of inter-est is health and wellness, for example Withings and iHealth. Pulse oximetry can be recorded up to 24 h in ambulatory patients frequently together with other sig-nals such as ECG, movements of the chest and abdo-men for respiratory rate, nasal air flow and pressure,
805 ms 800 ms 795 ms 810 ms Time [ms] sO 2 [%] 97% 99% 98% 100% 100%
Figure 2. Haemoglobin saturation waveform recorded continuously from a healthy individual. From the same signal two different pieces of physiological information can be derived: sO2(values in %) and duration of each cardiac cycle (values in ms) which is reciprocally related to heart rate.
body position, electroencephalography or other vital signals, e.g. SOMNOtouch RESP (somnomedics.eu/ products/new-somnotouch/somnotouch-resp) or ViSi Mobile Monitoring System (www.soterawireless.com). Although there is quite a substantial number of pulse oximeters that communicate with smartphones, pub-lished clinical studies validating such devices are rather scarce.28,29 Hudson et al.29tested the prototype phone oximeter in high- and low-medical resource environments (i.e. Canada and Uganda, respectively). However, the tests were mainly made for development purposes. Garde et al.30 tested a phone oximeter for a different purpose, i.e. diagnosing the obstructive sleep apnoea in a group of 68 children during a night’s sleep, and compared the results with polysomnography. Their conclusion was that phone oximeters might be helpful as sleep-screening tools to identify children with signifi-cant obstructive sleep apnea.
As already mentioned, a separate device or periph-eral with red/infrared light sensors is required to
meas-ure SpO2. However, quite recently, digiDoc
Technologies (digidoctech.no), has released probably the first in the world solution that does not need any additional equipment for oximetry. Their product measures SpO2 only with the iPhone camera. So far, there are no clinical studies comparing the digiDoc app for SpO2 with validated pulse oximeters.
Potential, pitfalls, and perspectives
With the introduction of the iPhone in 2007 the smart-phone era really took off. The ease of use and the pro-cessing power in smartphones having continuous connection to the Internet opened dozens of new opportunities also in the health domain. In parallel, new and improved sensor technologies have been devel-oped to self-measure cardiovascular signals (such as blood pressure and SpO2), something previously pos-sible only in the hospital or with the help of a general practitioner.
The potential of cardiovascular signal acquisition, storage and analysis by smartphones is already recog-nised and very fascinating. Recording, monitoring, and communication of heart rate, blood pressure, ECG, SpO2 and of many other vital signals may increase the chance of survival for thousands of people who have limited access to medical care. This can also reduce the costs of healthcare and contribute to better management of patients with chronic diseases like heart failure, diabetes or hypertension, or of individuals at high risk of premature death like patients with long
QT syndrome, or hypertrophic cardiomyopathy.
Transferring medical care from the hospital to the home environment can be crucial in building a culture
of prevention, early diagnosis, and effective
rehabilitation that would help bend down the costs of care. Technology can act as workforce multiplier as physicians make better diagnoses and treatment deci-sions and gain up to 30% in productivity by saving time in accessing and analysing clinical information.31 Cardiac implant manufacturers offer cardiologists med-ical apps that allow them to receive and review alerts from patients, together with a variety of useful analytics.32
Advances in technology make data collection on smartphones cheaper and more convenient allowing individuals to quantify their biometrics and share them with their social network.8 Medical devices are available practically over-the-counter and at ever decreasing prices. Substantial amounts of health, life-style, and activities data are collected from mobile devices such as smartphones, smart watches, glasses, tablets, patches, bracelets, and necklaces with sensors and implants. It is estimated that in the US, 30% of healthy individuals regularly measure and monitor their heart rate, blood pressure or SpO2 as they engage in a healthy lifestyle. Mobile apps reminders and behav-ioural nudges help them stay on track with medication, exercise, and healthy living. In addition to heart rate and blood oxygenation, skin temperature, body pos-ition, activity level, blood pressure, respiratory rate, ECG, pressure and flow in the airways, many more bio-signals can be continuously monitored. Often the recording of such signals can last at least 24 h or longer, sometimes up to several weeks. The potential of such devices exceeds the possibilities of standard solutions used for decades in medicine like for example a 24-hour Holter ECG or 24-hour ambulatory blood pressure monitor. This is an unprecedented opportunity for clinicians to access health data before clinical symp-toms occur or when early indications are barely present. Collecting data from many individuals allows to study large cohorts with increasing statistical power, i.e. Big Data analytics, which was impossible in the past.
Along with remarkable innovations come several pitfalls, risks and limitations. Further research is needed to identify the correct measurement methods for different pathologies, e.g. non-ECG based measure-ments of heart rate such as pulsometry devices are not accurate for the detection of AF whereas they are suf-ficient for health and fitness. Moreover, the acquisition of multiple signals at a time may compensate for tran-siently inaccurate measurements.
The use of smartphone sensors for the measurement of vital signs is a new area and quite often, during the development of mobile apps, validation of essential components does not receive adequate attention. ECG recorders, blood pressure monitors or pulse oxim-eters made by medical device vendors producing vali-dated devices that have already obtained FDA
approval, can be supplemented with Bluetooth connect-ivity, and can work reliably with a smartphone in non-clinical settings. New companies, in an effort to reduce costs and test novel ideas, could start producing devices, sensors, and apps that measure vital signals without substantial validation, regulatory clearance or certifications. They forego regulatory approval and robust validations efforts, positioning their apps and associated sensors in the area of health and wellness. The resulting products could impose a safety risk for their users, if utilised for medical purposes.
Legal regulations for the use of mobile health apps and devices for vital signs recording, storing, transfer-ring, analysing, or problems related to sensitive per-sonal data frequently neglected by app developers and vendors, may undermine consumer confidence and trust. The FDA evaluates mobile medical apps that serve as accessories to regulated medical devices (Class II or III) or are intended to transform a mobile platform to a medical device.33Recently, it issued guid-ance on mobile medical apps and identified different classes of apps for which it may exercise enforcement discretion.34,35 Regulatory scrutiny may be applied on health apps intended for individuals to collect, log, track and trend data such as blood glucose, blood pres-sure, heart rate, weight or other data from a device to eventually share with a health care provider, or upload it to an online (cloud) database, personal or electronic health record (EHR). In general, if the ‘intended use’ of the device is diagnostic rather than informational, regu-latory scrutiny is likely.36In the future, appstores may play a stronger role as well by setting a higher or lower bar as to which apps they accept to host. However, the smartphone and telecommunications industry is con-cerned that excessive regulation might hinder competi-tion, challenging the traditional role of regulatory bodies such as the FDA.37,38 The limited success of early third party validation/certification ventures like HappTique,39 a third-party health app validator/certi-fier, commercial spin-off of the NY hospital associ-ation, indicates that perhaps a different paradigm embodying a dynamic ‘social’ community approach is called for.
Another limitation is the currently poor integration
of mobile health apps with EHR systems.
Interoperability standards in this area are quite nas-cent, but IHE and HL7 are rapidly catching up, with innovative and lean standards like HL7 FHIR (www.HL7.org/FHIR).
There are many, so-called medical, personal health or lifestyle apps, available. An important question is in what way these apps will improve health outcomes? These apps may be exciting from a technological point of view, but they can only be truly useful if they have a positive impact on health. While the use
of health apps measuring vitals on smartphones is still in its infancy, it might be difficult to systematically evaluate the possible cost-benefits or quality of life improvements. Early findings, however, suggest that mobile health apps can have a positive impact on health outcomes: e.g. researchers at the Mayo Clinic found that incorporating a smartphone app into car-diac rehabilitation reduces emergency room visits and hospital readmissions by 40%.40,41
An important perspective that can impact adoption is reimbursement as a recent meeting of Apple health executives with insurance companies reveals.42 In case that in the near future, apps and peripheral devices, such as described in this paper, are prescribed to be used by patients, reimbursement should be clear. Some devices might be expensive and some applied sen-sors could perhaps be disposable, used only once, e.g. contact lenses or bio-signal patches that are single use only. Thus, there are costs involved, whether for the patients themselves or for the health insurance compa-nies. As the health insurance companies are currently in contact with the smartphone companies, it might be possible that the application of such vital signs meas-urements and monitoring will be realised very soon. At the time of writing, there is high anticipation for new technologies that will be soon released on the market from different companies, with novel sensors on-board to monitor several different body parameters that could herald the eve of a new era for personal healthcare.43,44
Summary
Smartphones, mobile ‘apps’, social media, Big Data analytics, and the cloud are changing the practice of medicine. Rapid technological progress in the area of biosensors and health apps allows the acquisition and analysis of vital signs with the smartphone as a personal hub. Increasing the usability of medical technology and bringing it closer to the people has the advantage of enabling the possibility for unprecedented patient par-ticipation and active engagement in their own medical education and healthcare. For example, ECG monitor-ing usmonitor-ing smartphones allows users to learn about and characterise their heart rate and rhythm, and it has the potential to provide global identification of arrhyth-mias. Home blood pressure measurement in combin-ation with a smartphone app allows people to monitor and document their blood pressure over time, show and discuss the results with their doctor and perhaps also their social network.
Some smartphone based technological solutions have gone through FDA clearance and thus can be considered reliable. Atrial Fibrillation seems to repre-sent one important field of application for this
technology, with benefits both in community AF screening and detection of AF recurrence.
Those that have not received regulatory approval may still be reliable, but it is uncertain whether they are acceptable for clinical or personal use. Proper infor-mation is needed to avoid misuse of health applications not designed for medical purposes (i.e. for fitness). This includes proper validation and knowledge of limits of operability.
The outlook of this technology for improving public awareness of health metrics and for the early diagnosis of cardiac symptoms is quite promising. At the same time, there is hope that the use of technology in large scale by serving as a workforce multiplier will improve access to medical expertise and contribute to the sus-tainability of healthcare systems worldwide.
Acknowledgements
Members of the ESC WG on e-Cardiology have been a con-stant driver and motivation behind this work. The authors would like to thank them collectively and individually.
Funding
Catherine Chronaki has been supported by the European Commission under contract ‘FP7-610756’ Trillium Bridge project.
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