Wireless Heart Sensor for Capturing Cardiac Orienting Response for Prediction of Neurodevelopmental Delay in Infants

Abstract

Early identification of infants at risk of neurodevelopmental delay is an essential public health aim. Such a diagnosis allows early interventions for infants that maximally take advantage of the neural plasticity in the developing brain. Using standardized physiological developmental tests, such as the assessment of neurophysiological response to environmental events using cardiac orienting responses (CORs), is a promising and effective approach for early recognition of neurodevelopmental delay. Previous CORs have been collected on children using large bulky equipment that would not be feasible for widespread screening in routine clinical visits. We developed a portable wireless electrocardiogram (ECG) system along with a custom application for IOS tablets that, in tandem, can extract CORs with sufficient physiologic and timing accuracy to reflect the well-characterized ECG response to both auditory and visual stimuli. The sensor described here serves as an initial step in determining the extent to which COR tools are cost-effective for the early screening of children to determine who is at risk of developing neurocognitive deficits and may benefit from early interventions. We demonstrated that our approach, based on a wireless heartbeat sensor system and a custom mobile application for stimulus display and data recording, is sufficient to capture CORs from infants. The COR monitoring approach described here with mobile technology is an example of a desired standardized physiologic assessment that is a cost-and-time efficient, scalable method for early recognition of neurodevelopmental delay.

Keywords: auditory and visual stimuli; cardiac orienting response; electrocardiogram; mobile application; monitoring; neurodevelopment delay; tablet; wireless sensor.

Figure 1

The cardiac-oriented response is triggered by stimulus display. (A) The visual stimulus category was composed of the presentation of a blank screen followed by the picture of a baby or woman’s face and then a blank. In this pictorial example of the habituation session, a baby face picture was presented ten times. Then, during the dishabituation session, the other face picture was used; in this example, a woman’s face followed by a blank was presented five times. Repetitions and duration that each visual stimulus displayed are depicted at the top-left and bottom-right corners of the pictures, respectively. (B) Previous unpublished data representing a canonical averaged heartbeats deceleration during the first three images presented for the habituation (baby face picture) and dishabituation (woman face) visual stimuli. Data were collected with a commercial setup, different from that described here. Dots and bars represent mean and standard error, respectively, calculated from 162 subjects with no prenatal alcohol exposure.

Figure 2

COR sensor. (A) Top view of the board showing the ECG components and BLE set chip for wireless communication. The bottom view shows the battery holder for a CR2030 coin cell. (B) The end-to-end length includes ground (black), main lead (blue), and the 3D-printed black plastic encase that protects the primary circuit. (C) An example of leads positioning on a 4-year-old child.

Figure 3

COR mobile app running on a 10” iOS tablet. (A) The primary layer shows a COR sensor listed during BLE advertising, just before the connection between the sensor and the app is established. When the user clicks on the COR sensor name listed under “All Devices,” such a connection between both ends is established. (B) Since the connection between the sensor and the app, the user can see the heart rate information displayed on the left under “Heart rate (BPM).” (C) When the experiment is completed, the user gets feedback regarding deceleration as the averaged BPM for the first three trials for habituation and dishabituation at each stimuli category. (D) This final layer shows the experiment stored in the iOS device and provides the option to select and share a selected experiment by email.

Figure 4

Car chair support and tablet holder system. (A,B): Rear and frontal view of the mechanical frame attached to the acrylic base that allows to hold and accommodate a tablet in front of the infant seat on the car chair. (C): Car seat for infants of 4–22 pounds. (D,E): Lateral views of the same system support a larger car seat for infants of 22–40 pounds and a tablet while the system is placed on the top of a high chair. Note: the chairs used on this figure are examples of how we took advantage of combining such chairs and the COR system. In the text we provided suggestions on how to attach both components, however the use of chairs with the COR system is under your own risk.

Figure 5

Response of COR sensor to synthetic and heart biopotentials. (A): The average curve of two ramps of artificial ECG signals on steps of 0.1 Hz is equivalent to 6 BPM every 12 s. It is possible to see the response of the COR sensor is stable at different frequencies having a coefficient of variation (CV in the insert) < 1% when the input signal is < 3 Hz. (B): The COR sensor mostly responds linearly to synthetic ECG signals at different frequencies (Hz) and amplitudes (mV) that match the parameters of biological ECG signals. (C): The COR sensor can capture variations of 4 s (yellow column) or longer on the synthetic input signal of 0.1 Hz (grey curve) through time, making this sensor suitable to detect differences in the heartbeat rhythm between populations (i.e., healthy vs. neurodevelopment delayed subjects). (D): Raw R-to-R time expressed as BPM during a whole session of visual stimulation. (E): COR triggered by the visual stimulation depicted in D where the woman pictures were used as the habituation stimulus, while the baby pictures were used as the dishabituation stimulus. The black curve represents the averaged cardiac deceleration in response to the first three visual habituation images (yellow columns) of an infant with no prenatal alcohol exposure from an Atlanta cohort. (F): The black trace represents the averaged cardiac deceleration in response to the first three 400 Hz habituation tones of a subject with no prenatal alcohol exposure during gestation from the Ukraine cohort. The gray curves are the averaged COR to the first three dishabituation pictures (baby face) and tones (700 Hz) for each subject and stimulus modality, respectively.