Electrocardiogram-based biometrics for user identification - Using your heartbeat as a digital key.

External biometrics such as thumbprint and facial recognition have become standard tools for securing our digital devices and protecting our data. These systems, however, are potentially prone to copying and cybercrime access. Researchers have therefore explored internal biometrics, such as the electrical patterns within an electrocardiogram (ECG). The heart's electrical signals carry sufficient distinctiveness to allow the ECG to be used as an internal biometric for user authentication and identification. Using the ECG in this way has many potential advantages and limitations. This article reviews the history of ECG biometrics and explores some of the technical and security considerations. It also explores current and future uses of the ECG as an internal biometric.

Comparative study of a single lead ECG in a wearable device.

BACKGROUND: Technological advances have led to electrocardiograph (ECG) functionality becoming increasingly accessible in wearable health devices, which has the potential to vastly expand the clinician's ability to monitor, diagnose, and manage cardiac health conditions. However, achieving the high signal quality necessary to make an accurate and confident diagnosis is inherently challenging on consumer device-acquired ECGs. Effective signal conditioning is crucial to make ECG data from wearable devices clinically actionable. OBJECTIVE: This study evaluates the heart rate (HR) performance of ECG data collected on the HeartKey® Test Watch, a single lead, dry electrode wrist wearable, against data acquired on two criterion devices: the Bittium® Faros 180, a gold standard wet electrode ambulatory monitoring device, and the HeartKey Chest Module. METHODS: ECG data was simultaneously acquired on three devices during a multi-stage protocol (sitting, walking, standing) designed to reflect the motion noise of real-life scenarios. Raw ECGs from the HeartKey Test Watch and HeartKey Chest Module were processed through HeartKey software, and the accuracy of the outputted heart rate data was compared to that of the criterion device at each stage of the protocol. A beat rejection analysis was performed to provide insight into the degree of high-frequency noise present in ECGs recorded on the HeartKey Test Watch. RESULTS: Data acquired on the HeartKey Test Watch and processed by HeartKey software generated HR metrics that closely matched that of the criterion devices throughout the protocol. Bland-Altman analysis showed a mean absolute HR difference of 0.74, 1.21, 0.80 bpm during the sitting, walking, and standing stages respectively, which is within the ± 10% or ±5 bpm range required by ANSI EC13. ECG data from the HeartKey Test Watch had a higher beat rejection rate relative to the HeartKey Chest Module (8.5% vs ∼0%) due to the excessive high-frequency noise generated during the motion-based protocol. CONCLUSION: HeartKey software demonstrated highly accurate HR performance, comparable to that of the criterion Faros device, when processing challenging ECG data acquired on a single lead, dry electrode wrist wearable during both non-motion and motion-based protocols.

A universal, high-performance ECG signal processing engine to reduce clinical burden.

BACKGROUND: Electrocardiogram (ECG) signal conditioning is a vital step in the ECG signal processing chain that ensures effective noise removal and accurate feature extraction. OBJECTIVE: This study evaluates the performance of the FDA 510 (k) cleared HeartKey Signal Conditioning and QRS peak detection algorithms on a range of annotated public and proprietary ECG databases (HeartKey is a UK Registered Trademark of B-Secur Ltd). METHODS: Seven hundred fifty-one raw ECG files from a broad range of use cases were individually passed through the HeartKey signal processing engine. The algorithms include several advanced filtering steps to enable significant noise removal and accurate identification of the QRS complex. QRS detection statistics were generated against the annotated ECG files. RESULTS: HeartKey displayed robust performance across 14 ECG databases (seven public, seven proprietary), covering a range of healthy and unhealthy patient data, wet and dry electrode types, various lead configurations, hardware sources, and stationary/ambulatory recordings from clinical and non-clinical settings. Over the NSR, MIT-BIH, AHA, and MIT-AF public databases, average QRS Se and PPV values of 98.90% and 99.08% were achieved. Adaptable performance (Se 93.26%, PPV 90.53%) was similarly observed on the challenging NST database. Crucially, HeartKey's performance effectively translated to the dry electrode space, with an average QRS Se of 99.22% and PPV of 99.00% observed over eight dry electrode databases representing various use cases, including two challenging motion-based collection protocols. CONCLUSION: HeartKey demonstrated robust signal conditioning and QRS detection performance across the broad range of tested ECG signals. It should be emphasized that in no way have the algorithms been altered or trained to optimize performance on a given database, meaning that HeartKey is potentially a universal solution capable of maintaining a high level of performance across a broad range of clinical and everyday use cases.

Delayed presentation of right ventricular lead perforation following defibrillator implantation: a case report.

BACKGROUND: Perforation of a device lead through the myocardium is a recognized complication of cardiac device implantation. The associated morbidity and mortality are significant, even though it is a relatively rare complication. Therefore, it is vital for acute clinicians to be aware of the diagnosis and subsequent management of myocardial perforation. CASE SUMMARY: We present the case of a 48-year-old woman who presented to the emergency department 1 month following implantable cardioverter-defibrillator implantation with chest and shoulder pain. Initial assessment revealed bilateral pleural effusions and anaemia. Computerized tomography of her chest and abdomen demonstrated a pericardial effusion, but it was transthoracic echocardiography that confirmed the diagnosis of right ventricular perforation. Urgent system revision was undertaken. DISCUSSION: This case highlights the importance of clinical suspicion and the use of diagnostic echocardiography as an important diagnostic tool in symptomatic patient's post-cardiac device implantation.

A study to assess a novel automated electrocardiogram technology in screening for atrial fibrillation.

INTRODUCTION: Atrial fibrillation is often asymptomatic and un-diagnosed in the community resulting in an increased risk of heart failure and stroke to those patients. We evaluated the effectiveness, tolerability, and accuracy of a novel six-channel electrocardiogram digital-health screening device, the RhythmPad, for the detection of atrial fibrillation. METHODS: Seven hundred and fifty-two participants attending the cardiology department were recruited. Two recordings were taken-a six-lead electrocardiogram using the RhythmPad device and a standard 12-lead electrocardiogram. Recorded traces were analyzed by two blinded cardiologists. The computer-generated automated diagnostic reports from both systems were also compared. Post-participation feedback was obtained from study participants using a three-part questionnaire. RESULTS: The sensitivity of the six-lead electrocardiogram compared to the 12-lead electrocardiogram, analyzed by two blinded cardiologists, for the detection of normal sinus rhythm was 95.9%, with a specificity of 97.2%. The sensitivity for the detection of atrial fibrillation using the six-lead ECG was 93.4%, with specificity 96.8%. The six-lead automated diagnostic report had a sensitivity and specificity of 97.5% and 98.6%, respectively, for correctly diagnosing normal sinus rhythm. For the correct diagnosis of atrial fibrillation, the six-lead automated diagnostic report had a sensitivity and specificity of 95.4% and 98.8%, respectively. A total of 95.4% of participants found RhythmPad to be comfortable, with only 0.5% preferring the 12-lead ECG device in comparison to six-lead ECG acquisitions. CONCLUSION: The RhythmPad digital health device and its automated diagnostic report were highly accurate in detecting atrial fibrillation when compared to a standard 12-lead electrocardiogram.

Surfactant Charge Modulates Structure and Stability of Lipase-Embedded Monolayers at Marine-Relevant Aerosol Surfaces.

Lipases, as well as other enzymes, are present and active within the sea surface microlayer (SSML). Upon bubble bursting, lipases partition into sea spray aerosol (SSA) along with surface-active molecules such as lipids. Lipases are likely to be embedded in the lipid monolayer at the SSA surface and thus have the potential to influence SSA interfacial structure and chemistry. Elucidating the structure of the lipid monolayer at SSA interfaces and how this structure is altered upon interaction with a protein system like lipase is of interest, given the importance of how aerosols interact with sunlight, influence cloud formation, and provide surfaces for chemical reactions. Herein, we report an integrated experimental and computational study of Burkholderia cepacia lipase (BCL) embedded in a lipid monolayer and highlight the important role of electrostatic, rather than hydrophobic, interactions as a driver for monolayer stability. Specifically, we combine Langmuir film experiments and molecular dynamics (MD) simulations to examine the detailed interactions between the zwitterionic dipalmitoylphosphatidylcholine (DPPC) monolayer and BCL. Upon insertion of BCL from the underlying subphase into the lipid monolayer, it is shown that BCL permeates and largely disorders the monolayer while strongly interacting with zwitterionic DPPC molecules, as experimentally observed by Langmuir adsorption curves and infrared reflectance absorbance spectroscopy. Explicitly solvated, all-atom MD is then used to provide insights into inter- and intramolecular interactions that drive these observations, with specific attention to the formation of salt bridges or ionic-bonding interactions. We show that after insertion into the DPPC monolayer, lipase is maintained at high surface pressures and in large BCL concentrations by forming a salt-bridge-stabilized lipase-DPPC complex. In comparison, when embedded in an anionic monolayer at low surface pressures, BCL preferentially forms intramolecular salt bridges, reducing its total favorable interactions with the surfactant and partitioning out of the monolayer shortly after injection. Overall, this study shows that the structure and dynamics of lipase-embedded SSA surfaces vary based on surface charge and pressure and that these variations have the potential to differentially modulate the properties of marine aerosols.

Biomarker Assays for Personalised Stroke Risk Assessment in Atrial Fibrillation.

BACKGROUND: Atrial fibrillation is a well-known independent risk factor for stroke yet there is no international consensus on guidelines regarding the introduction of anticoagulation in patients deemed at intermediate risk (e.g. CHA2DS2-VASc of 1). The evolution of cardiac biomarkers such as highly sensitive troponins and B-type natriuretic peptide as well as data on D-dimers, may offer incremental enhancements for personalized thromboembolism risk assessment. These markers provide prognostic data for risk of cardiovascular morbidities associated with atrial fibrillation and offer additional specificity for assessing stroke and thromboembolic risk. These assays may therefore enhance risk prognosis in atrial fibrillation alongside conventional stroke risk stratification tool patients. We seek to explore the application of personalised risk assessment using the biomarkers to aid the clinician treating the patient with atrial fibrillation deemed to be at intermediate risk of stroke. CONCLUSION: The stroke risk assessment of a patient with an intermediate risk of stroke (CHA2DS2- VASc score 1) may be improved by using cardiac biomarkers such as highly sensitive troponin, BNP and D-dimers. We explore the application of these biomarkers to provide personalised risk assessment to help a patient with AF decide on whether to commence anticoagulation.

Permanent catheter drainage system for palliation of diuretic-resistant cardiac ascites.

We report the case of a 69-year-old man with dilated cardiomyopathy treated with a permanent catheter drainage system for diuretic resistant cardiac ascites. At 1 year follow-up, the patient had no heart failure related hospitalisations, displayed improved quality of life measures and had incurred no complications related to the catheter. Permanent tunnelled catheters are widely used to treat malignant ascites but may also be considered for palliation of cardiac ascites.

Is there a role for a local inpatient CT coronary angiography service in selected patients with acute coronary syndrome? A cohort analysis of inpatient tertiary centre referrals for invasive coronary angiography.

OBJECTIVE: To conduct a retrospective analysis of inpatients referred for invasive coronary angiography (ICA) at a tertiary centre, with suspected or confirmed acute coronary syndrome (ACS). METHODS: A retrospective cohort study was conducted at Jersey General Hospital. We evaluated 198 inpatients referred for ICA with suspected or confirmed ACS over a 3-year period. Patients presenting with ST elevation myocardial infarction were excluded. The primary outcome was to identify the number of patients who did not require subsequent coronary intervention following ICA. Patient variables were measured to establish those who met European Society of Cardiology (ESC) criteria for consideration of CT coronary angiography (CTCA) as an alternative to ICA. Cost of care for those referred for ICA was calculated. RESULTS: ICA demonstrated evidence of coronary heart disease requiring coronary intervention in 119 (60%) of the referred patients. 28 (35%) of the patients not requiring coronary intervention at ICA met ESC criteria for preassessment with CTCA. The cost of care for this subgroup was £9089 per patient. Inpatient CTCA was calculated at £376 per patient. CONCLUSIONS: Low-intermediate risk patients presenting with suspected or confirmed ACS to hospitals without onsite coronary revascularisation should be considered for in-hospital CTCA before consideration of ICA. Using CTCA as a gatekeeper for targeted ICA appears cost-effective, particularly for hospitals without the required onsite facilities.

Atrial fibrillation - new frontiers in anticoagulation.

Stroke is the most feared complication of atrial fibrillation but for over fifty years there has been no simple, effective preventative alternative to warfarin. The development of new risk algorithms such as CHADSVASC has resulted in more patients being recommended anticoagulation therapy. Fixed dose oral anticoagulation is a landmark in drug development for atrial fibrillation. The differences between the drugs are discussed and the trial data examined. As we enter this new frontier of therapy, there is no doubt that these drugs will transform the delivery of anticoagulation for patients with atrial fibrillation.

Digoxin - time to take the gloves off?

Digoxin has been used for hundreds of years to aid rate control in atrial fibrillation and as a positive inotrope in heart failure. Our familiarity with digoxin has allowed it to become easily prescribed even though there are data suggesting that use of digoxin may in fact result in increased mortality and pro-arrhythmia. Within this review we explain some of the outcome data associated with digoxin use to determine if it is time to take the gloves off and examine if we should still be using this drug in the 21st century.

Early aeromedical transfer after acute coronary syndromes.

AIMS: To investigate the safety and efficacy of early aeromedical transfer after acute coronary syndromes (ACS). The Island of Jersey is 160 km from the UK and as no catheter laboratory facilities exist locally, patients with ACS are transferred to tertiary centres by air ambulance in the UK for further investigations. METHODS: All patients transferred to the UK for investigation after ACS in 2008 were identified retrospectively from coronary care admission records and the local flight transfer database. Data were collected on patient demographics, diagnosis, time from presentation, flight duration, accompanying personnel and in-flight complications. Significant complications were defined as death, cardiac or respiratory arrest, sustained arrhythmia requiring electrical cardioversion or the need for endotracheal intubation. RESULTS: 65 patients (mean age 61.7 years; 80.0% male) were transferred for cardiac catheterisation after non-ST elevation myocardial infarction (n=30, 46.2%) or ST elevation myocardial infarction (n=23, 35.4%), or with unstable angina (n=12, 18.5%). Patients were transferred 3.6 ± 3.4 days after presentation; mean transfer time was 171.6 ± 38.8 min. The majority (90.8%) of patients were transferred with both a doctor and a nurse. There were no significant complications during transfer. Intra-transport medication with nitrates, diuretics, analgesia, antiemetics or antiarrhythmics was required in 15 (23.1%) patients. CONCLUSIONS: Aeromedical transfer after ACS is safe within 3 days of presentation. Given the minor nature of in-flight complications, a paramedic and coronary care nurse are sufficient medical escort for these patients.