Photoplethysmography

Atrial Fibrillation

1. Photoplethysmography and the detection of atrial fibrillation Natalie Kanis

2. Case Study

3. A 67-year-old Caucasian male presents to his PCP for a routine well-visit. He has a history of HTN and HLD on atorvastatin 10 mg daily and lisinopril 10 mg daily. He weighs 220 lbs. and is 69 in. tall (BMI 32.5 kg/m2). He is a non-smoker and only drinks alcoholic beverages on special occasions. At this visit he denies SOB, palpitations, dizziness, fatigue, and chest pain. His BP is 124/80 mmHg and his HR is 115. His physical exam is benign except for an irregularly irregular heart rhythm. An EKG reveals atrial fibrillation with a rapid ventricular response. An echo is performed showing “mild concentric left ventricular hypertrophy and mild left atrial enlargement.” His echo is otherwise normal. His lab values are all unremarkable. His CHA2DS2-VASc score is a 2; he is moderate-high risk for stroke. His HAS-BLED score is also a 2; he is at moderate risk for major bleeding. Anticoagulation should be considered.

4. Technology Photoplethysmography (PPG)

5. PPG Previously only detectable on EKGs, wearable patches, and implantable recorders, new technology on smartwatches and other portable devices may allow for detection of atrial fibrillation before adverse events via a non-invasive, cost-effective, portable technology. This technology is called photoplethysmography (PPG). PPG measures light transmission to a sensor placed on the skin near an artery. A pulse is detected by shining a light onto the skin and measuring the difference in light reflected to the sensor.

6. Use of Technology

7. PPG is present in some smartwatches, some applications on smartphones (utilizing the camera flash as the light source), and some handheld EKG devices. These devices and applications are available to consumers without provider prescription. While EKG is necessary for definitive diagnosis of atrial fibrillation, use of PPG can clue patients into heart rhythm abnormalities so they might seek medical attention. Devices such as the Apple Watch and Kardia Band are continuously worn, and the user is issue notifications if an irregular or fast heart rate is captured. Devices such as applications using a smartphone’s camera as a PPG sensor ( Cardiio Rhythm App) and the portable single-lead EKG monitoring devices ( MyDiagnostick and AliveCor Kardia Mobile Heart Monitor) are used by patients intermittently to check for arrythmias at the specific time of use. The FDA has approved the AliveCor Heart Monitor, the Apple Watch, and the Kardia Band for detection of rhythm abnormalities.

8. Cont. This table is from a review conducted by Raja et al. (2019). It discusses sensitivity and specificity of these heart monitoring devices in detecting atrial fibrillation. According to Rajakariar et al. (2018) 98% of patients preferred wearable technology to an event monitor while 90% stated they would use the technology to determine cardiac abnormalities.

9. Apple Watch

10. Kardia Band

11. Cardiio Rhythm Application

12. My Diagnostick

13. AliveCor Kardia Mobile EKG Monitor

14. Special Precautions

15. False positives may induce anxiety and worry in patients and may also increase number of unnecessary ER visits. Intermittent EKG monitoring is more sensitive than use of PPG for atrial fibrillation detection. Four times more cases of atrial fibrillation are diagnosed with EKG than PPG. Wearable technologies are less often worn by older patients who could benefit more from technology than younger patients. Should not be used as the sole diagnostic tool, but as a starting point for patients to seek medical help.

16. Expected Outcomes

17. The use of these monitoring devices should give the healthcare provider more insight into a patient’s cardiovascular health and lead to more prompt diagnosis of cardiovascular conditions. Patients should seek medical attention with notifications of irregular heart rates. It is expected that with more universal use of wearable/portable PPG monitoring devices patients should have earlier treatment of atrial fibrillation and other cardiovascular abnormalities and thus earlier implementation of stroke reduction strategies. The use of PPG is relatively new to healthcare and thus controversial as a diagnostic tool. More research needs to be conducted to garner more evidence into the clinical usefulness of portable PPG monitors. These devices/applications have the potential to lead to better patient outcomes and to become a useful tool for healthcare providers to monitor patients over a longer period.

18. Final Thoughts A patient like the one described in our case presentation could have been treated for his new atrial fibrillation sooner had he owned a device with a PPG sensor. A patient with numerous risk factors for atrial fibrillation could have been advised by a healthcare provider to invest in a wearable or portable heart monitor so that he could be alerted of an irregular or fast heart rate.

19. References Castaneda, D., Esparza, A,. Ghamari , M., Soltanpur , C. & Nazeran , H. (2019). A review on wearable photoplethysmography sensors and their potential future applications in health care. International Journal of Biosensors & Bioelectronics, 4(4). Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6426305/ Nelson, B.W. & Allen, N.B. (2019). Accuracy of consumer wearable heart rate measurement during an ecologically valid 24-hour period: intraindividual validation study. JMIR MHealth uHealth , 7(3). DOI 10.2196/10828 Raja, J.M., Elsakr , C., Roman, S., Cave, B., Pour- Ghaz , I., Nanda, A., Maturana , M., & Khouzam , R.N. (2019). Apple watch, wearables, and heart rhythm: where do we stand? Annals of Translational Medicine, 7(17). Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6787392/ Rajakariarlow , K., Koshy, A., Sajeev, J., Roberts, L. & Teh , A. (2018). Increased preference of wearable devices compared with conventional cardiac monitoring. Heart Lung and Circulation, 27. Retrieved from https://doi.org/10.1016/j.hlc.2018.06.288 Vega, C.P. (2019, April 1). Case clinic: a 67-year-old white male patient with atrial fibrillation risk factors. Clinical Advisor. https://www.clinicaladvisor.com/home/topics/cardiovascular-disease-information-center/case-clinic-a-67-year-old-white-male-patient-with-atrial-fibrillation-risk-factors/