An app developed by researchers at King's College London allows users to record their heartbeats using nothing more than their iPhones, New Scientist has reported. The simple technology that turns smartphones into stethoscopes is aimed at collecting heartbeat samples for researchers and has already made an impact by collecting over 100,000 recordings so far.

Doctors routinely use their analog stethoscopes to look for signs of heart-related ailments. Whether it is heart failure or atrial fibrillation, doctors are trained to listen to the heartbeat and look for signs of disease and ailments.

Modern-day devices like smartwatches are also equipped to measure heart rate and electrical activity of the heart. While these devices have proven to be useful in detecting incidents like heart failure, they are nowhere close to the medical diagnosis that clinicians provide.

The app called Echoes is simple to use and requires the user to sit in a quiet room. To record their heartbeat, the user simply needs to use the microphone and place it at four sites on their chest to make a recording.

The app then also converts the sound recording into waveform to provide a visual display of the heartbeats to the users. The app also collects information such as the user's age, gender, body mass index (BMI) as well as the phone version to analyze the quality of the recordings and determine which factors affect them.

The researchers used only iPhones for their experiment since the phone offers a better microphone. Once the users grant the required permissions, the recorded sounds are uploaded to the database which currently has more than 100,000 recordings.

The intention of the app was to get users interested in the health of their hearts. So, the app was not designed to give out medical advice or diagnoses. However, after considering the interest the app has generated and the data it has been collecting, the researchers are keen to equip it with the ability to answer questions about heart health.

Before doing so, the researchers wanted to know which factors may affect the quality of recordings. An analysis of nearly 7,600 recordings from 1,148 participants showed that neither BMI, not gender, nor the phone version impacted the quality of recordings made. The only factor that mattered was the age of the individuals.

Since the recordings and their waveforms remain available to users on their phones, it is possible for one to use other medical websites to get a diagnosis from the comfort of their homes. However, Pablo Lamata, the research lead of the team that developed the app, advises against doing so.

The researchers are also concerned about another outcome of such a service provided through a smartphone. Individuals who have health anxieties might end up checking their heart sounds too frequently, worried Leanne Grich of the British Heart Foundation, who helped fund the project, New Scientist said in its report.

The initial analysis of the recordings has been published in the journal European Heart Journal - Digital Health.

Smartphones are equipped with a high-quality microphone which may be used as an electronic stethoscope. We aim to investigate the factors influencing quality of heart sound recorded using a smartphone by non-medical users.

An app named Echoes was developed for recording heart sounds using iPhone. Information on phone version and users’ characteristics including sex, age, and body mass index (BMI) was collected. Heart sound quality was visually assessed and its relation to phone version and users’ characteristics was analysed. A total of 1148 users contributed to 7597 heart sound recordings. Over 80% of users were able to make at least one good-quality recording. Good-, unsure- and bad-quality recordings amounted to 5647 (74.6%), 466 (6.2%) and 1457 (19.2%), respectively. Most good recordings were collected in the first three attempts of the users. Phone version did not significantly change the users’ success rate of making a good recording, neither was sex in the first attempt (P = 0.41) or the first three attempts (P = 0.21). Success rate tended to decrease with age in the first attempt (P = 0.06) but not the first three attempts (P = 0.70). BMI did not significantly affect the heart sound quality in a single attempt (P = 0.73) or in three attempts (P = 0.14).

Smartphone can be used by non-medical users to record heart sounds in good quality. Age may affect heart sound recording, but hardware, sex, and BMI do not alter the recording.