Tero Koivisto

BackgroundHeart failure (HF) is the leading cause of hospitalization in individuals over 65 years of age. Identifying noninvasive methods to detect HF may address the epidemic of HF. Seismocardiography which measures cardiac vibrations transmitted to the chest wall has recently emerged as a promising technology to detect HF.ObjectivesIn this multicenter study, the authors examined whether seismocardiography using commercially available smartphones can differentiate control subjects from patients with stage C HF.MethodsBoth inpatients and outpatients with HF were enrolled from Finland and the United States. Inpatients with HF were assessed within 2 days of admission, and outpatients were assessed in the ambulatory setting. In a prespecified pooled data analysis, algorithms were derived using logistic regression and then validated using a bootstrap aggregation method.ResultsA total of 217 participants …

An apparatus for measuring a jugular vein pressure waveform includes a rotation sensor configured to produce a measurement signal when being against a skin of an individual and in a movement sensing relation with a jugular vein of the individual. The apparatus includes a processing system configured to receive the measurement signal and produce a waveform of a motion of the skin in a direction perpendicular to the skin based on the measurement signal indicative of rotation of the rotation sensor, where the waveform of the motion of the skin is indicative of the jugular vein pressure waveform. The rotation sensor that measures rotation is more insensitive to movements not related to variation of the jugular vein pressure than for example an acceleration sensor.

Results from two independent clinical validation studies for measuring hemodynamics at the patient's bedside using a compact finger probe are reported. Technology comprises a barometric pressure sensor, and in one implementation, additionally, an optical sensor for photoplethysmography (PPG) is developed, which can be used to measure blood pressure and analyze rhythm, including the continuous detection of atrial fibrillation. The capabilities of the technology are shown in several form factors, including a miniaturized version resembling a common pulse oximeter to which the technology could be integrated in. Several main results are presented: i) the miniature finger probe meets the accuracy requirements of non‐invasive blood pressure instrument validation standard, ii) atrial fibrillation can be detected during the blood pressure measurement and in a continuous recording, iii) a unique comparison …

The right internal jugular vein is connected to the right atrium of the heart via the superior vena cava, and consequently its pressure, known as the jugular venous pressure or the jugular venous pulse (JVP), is an important indicator of cardiac function. The JVP can be estimated visually from the neck but it is rather difficult and imprecise. In this article we propose a method to measure the JVP using a motion sensor patch attached to the neck. The JVP signal was extracted from the sensor’s 3-axes gyroscope signal and aligned with simultaneously measured ECG and seismocardiogram signals.The method was tested on 20 healthy subjects. The timings of the characteristic JVP waves were compared with the ECG R peaks and seismocardiogram heart sounds S1 and S2. The JVP was reliably measured from 18 subjects with all three waves identified. The timings of the waves were also physiologically plausible when …

IntroductionDuring the transcatheter aortic valve replacement (TAVR) procedure, hemodynamic measurements can be used to evaluate transcatheter heart valve (THV) performance. We hypothesized that the occurrence of a significant decrease in invasive aortic pressure immediately after annular contact by a self-expanding THV indicates effective annular sealing. This phenomenon could thus be used as a marker for the occurrence of paravalvular leak (PVL).MethodsThirty-eight patients undergoing TAVR procedure with a self-expandable Evolut R or Evolut Pro (Medtronic) valve prosthesis were included in the study. Drop in aortic pressure during valve expansion was defined as a decrease in systolic pressure of 30 mmHg immediately after annular contact. The primary endpoint was the occurrence of more than mild PVL immediately after valve implantation.ResultsA pressure drop was seen in 60.5% (23/38) of …

Objective Cardiac resynchronization therapy (CRT) is commonly used to manage heart failure with dyssynchronous ventricular contraction. CRT pacing resynchronizes the ventricular contraction, while AAI (single-chamber atrial) pacing does not affect the dyssynchronous function. This study compared waveform characteristics during CRT and AAI pacing at similar pacing rates using seismocardiogram (SCG) and gyrocardiogram (GCG), collectively known as mechanocardiogram (MCG). Approach We included 10 patients with heart failure with reduced ejection fraction and previously implanted CRT pacemakers. ECG and MCG recordings were taken during AAI and CRT pacing at a heart rate of 80 bpm. Waveform characteristics, including energy, vertical range (amplitude) during systole and early diastole, electromechanical systole (QS2) and left ventricular ejection time (LVET), were derived by considering 6 …

Our aim is to develop a blood pressure (BP) measurement technology that could be integrated into a finger-worn pulse oximeter, eliminating the need for a brachial cuff. We present a miniature cuffless tonometric finger probe system that uses the oscillometric method to measure BP. Our approach uses a motorized press that is used to apply pressure to the fingertip to measure BP. We verified the functionality of the device in a clinical trial (n = 43) resulting in systolic and diastolic pressures ((mean ± SD) mmHg) of (−3.5 ± 8.4) mmHg and (−4.0 ± 4.4) mmHg, respectively. Comparison was made with manual auscultation (n = 26) and automated cuff oscillometry (n = 18). In addition to BP, we demonstrated the ability of the device to assess arterial stiffness (n = 18) and detect atrial fibrillation (n = 6). We were able to introduce a sufficiently small device that could be used for convenient ambulatory measurements with …

Background Heart failure (HF) is the leading cause of hospitalization in people over the age of 65 years. More recently, cardiac motion sensor technology has emerged as a promising technology to detect HF. Methods In this multicenter study, we examined whether accelerometer and gyroscope signals from motion sensors collected using commercially available smartphones can classify HF status. Participants were enrolled from Finland and the United States. Participants hospitalized with acute decompensated HF were assessed in the acute state and re-assessed in the stabilized state prior to discharge. Outpatient participants were assessed in the stable state. In a pre-specified pooled data analysis, state specific algorithms to detect HF were first derived using logistic regression and validated using boostrap aggregation method (10 repeats) followed by sensitivity analysis in …

ES2607721B2 (es)* 2015-10-02 2019-07-04 Univ Catalunya Politecnica Método y aparato para estimar el tiempo de tránsito del pulso aórtico a partir de intervalos temporales medidos entre puntos fiduciales del balistocardiograma

Atrial fibrillation (AFib) is the most common heart arrhythmia in the world but detecting it can be challenging. For this reason, a detection system consisting of a wearable electrocardiogram (ECG) device, a smart phone application and an algorithm was created. The wearable device was designed to be aesthetically simple yet attractive and be worn either as a necklace or a keychain so that it would always be within reach. The overall usability was also a design goal from the start, requiring the user to only touch the device and start a measurement from the smart-phone application with a press of a button. The recorded data was processed with an AFib detection algorithm created based on the Chapman university's database with over 10,000 patients with different heart rhythms. The algorithm is a rule-based detection method, which uses heart rate variability and auto-correlation features. Motion artifacts were also …

The purpose of this study is to attempt to identify acute myocardial infarction with high frequency serial electrocardiogram which both are ECG analyzing techniques. The idea is to combine these two techniques and see if changes between different ECGs from the same person can provide us with some information, whether it being in the high frequency or normal frequency range of ECG. A heart attack can occur at any time and therefore the possibility of using a wearable device was also researched. To answer the questions, an existing database which contained multiple ECGs for each person with high sampling frequency was used. On top of this, a new serial ECG database was gathered using a wearable device designed by the University of Turku. Using multiple ECGs, features were extracted from the signals and then used in different machine learning methods in order to classify the subjects. All of the …

Novel means to minimize treatment delays in patients with ST elevation myocardial infarction (STEMI) are needed. Using an accelerometer and gyroscope on the chest yield mechanocardiographic (MCG) data. We investigated whether STEMI causes changes in MCG signals which could help to detect STEMI. The study group consisted of 41 STEMI patients and 49 control patients referred for elective coronary angiography and having normal left ventricular function and no valvular heart disease or arrhythmia. MCG signals were recorded on the upper sternum in supine position upon arrival to the catheterization laboratory. In this study, we used a dedicated wearable sensor equipped with 3-axis accelerometer, 3-axis gyroscope and 1-lead ECG in order to facilitate the detection of STEMI in a clinically meaningful way. A supervised machine learning approach was used. Stability of beat morphology, signal strength, maximum amplitude and its timing were calculated in six axes from each window with varying band-pass filters in 2–90 Hz range. In total, 613 features were investigated. Using logistic regression classifier and leave-one-person-out cross validation we obtained a sensitivity of 73.9%, specificity of 85.7% and AUC of 0.857 (SD = 0.005) using 150 best features. As a result, mechanical signals recorded on the upper chest wall with the accelerometers and gyroscopes differ significantly between STEMI patients and stable patients with normal left ventricular function. Future research will show whether MCG can be used for the early screening of STEMI.

Heart failure (HF) is a disease related to impaired performance of the heart and is a significant cause of mortality and treatment costs in the world. During its progression, HF causes worsening (decompensation) periods which generally require hospital care. In order to reduce the suffering of the patients and the treatment cost, avoiding unnecessary hospital visits is essential, as hospitalization can be prevented by medication. We have developed a data-collection device that includes a high-quality 3-axis accelerometer and 3-axis gyroscope and a single-lead ECG. This allows gathering ECG synchronized data utilizing seismo- and gyrocardiography (SCG, GCG, jointly mechanocardiography, MCG) and comparing the signals of HF patients in acute decompensation state (hospital admission) and compensated condition (hospital discharge). In the MECHANO-HF study, we gathered data from 20 patients, who each had admission and discharge measurements. In order to avoid overfitting, we used only features developed beforehand and selected features that were not outliers. As a result, we found three important signs indicating the worsening of the disease: an increase in signal RMS (root-mean-square) strength (across SCG and GCG), an increase in the strength of the third heart sound (S3), and a decrease in signal stability around the first heart sound (S1). The best individual feature (S3) alone was able to separate the recordings, giving 85.0% accuracy and 90.9% accuracy regarding all signals and signals with sinus rhythm only, respectively. These observations pave the way to implement solutions for patient self-screening of the HF using …

Objective The purpose of this research is to develop a new deep learning framework for detecting atrial fibrillation (AFib), one of the most common heart arrhythmias, by analyzing the heart's mechanical functioning as reflected in seismocardiography (SCG) and gyrocardiography (GCG) signals. Jointly, SCG and GCG constitute the concept of mechanocardiography (MCG), a method used to measure precordial vibrations with the built-in inertial sensors of smartphones. Approach We present a modified deep residual neural network model for the classification of sinus rhythm, AFib, and Noise categories from tri-axial SCG and GCG data derived from smartphones. In the model presented, pre-processing including automated early sensor fusion and spatial feature extraction are carried out using attention-based convolutional and residual blocks. Additionally, we use bidirectional long short-term memory layers on top of …

Differences in cardiac time intervals (CTIs) have previously been shown in different patient groups with varying levels of cardiac function. These studies relied on methods such as conventional echocardiography or tissue doppler imaging performed by a specialist to extract CTIs. The goal of this study was to evaluate the ability of using a combination of single lead ECG and 3-axis seismocardiography (SCG) from a sensor placed on a subject's sternum to automatically extract CTIs. For each subject, pre-ejection period (PEP), left ventricular ejection time ( $L$ VET), total systolic time $(TST)$ , and total diastolic time $(TDT)$ , which were normalized by the mean heart rate representing the entire recording were extracted using a custom developed algorithm. LVET was on average 20.5 % shorter in the NKHCD group $vs$ PRE-TAVI $(p< 0.05)$ ) and 5.9% shorter in the $HCD$ group $vs$ PRE-TAVI $(p> 0.05 …

An apparatus for measuring functionality of an arterial system of an individual includes a photoplethysmography sensor for emitting, to the arterial system, electromagnetic radiation having a wavelength in the range from 475 nm to 600 nm and for receiving a part of the electromagnetic radiation reflected off the arterial system. The apparatus further includes a pressure instrument for managing mechanical pressure applied on the arterial system when the photoplethysmography sensor emits and receives the elec tromagnetic radiation to and from the arterial system. The effect of the mechanical pressure on the envelope of the reflected electromagnetic radiation can be used for deter mining diastolic blood pressure of arteries or for determin ing whether there is normal endothelial function.

Bed based ballistocardiography (BCG) is a prime candidate for at home and nighttime monitoring especially in the growing elderly population because co-operation from the user is not required to be able to record signals. One issue with BCG is that the signal quality has intra-and inter-person variability based on factors such as age, gender, body position, and motion artifacts, making it challenging to accurately measure heart rate. A rule-based algorithm which considers all eight available BCG channels simultaneously from a given time epoch was developed using continuous wavelet transform (CWT) to extract the localized time-frequency representation of each epoch and then an averaging method was applied across the different scales of the CWT to produce a 1-dimensional array. Autocorrelation was then applied to this array to produce a heart rate estimate based on the lag between the autocorrelation …

An apparatus for producing information indicative of cardiac condition includes a processing system (301) for receiving a rotation signal indicative of rotational movement of a chest. The processing system is configured to form one or more indicator quantities each being derivable from an energy spectral density based on one or more samples of the rotation signal, where each sample has a temporal length. The processing system is configured to determine an indicator of cardiac condition on the basis of the one or more indicator quantities. The determination of the cardiac condition is based on that for example myocardial infarction causes changes in the energy spectral density. Thus, it is possible to distinguish between for example myocardial infarction and plain heartburn.

An apparatus for producing information indicative of cardiac abnormality, for example Heart failure with preserved ejection fraction “HFpEF”, includes a signal interface for receiving a signal indicative of cardiac motion and a processing system coupled to the signal interface. The processing system is configured to extract, from the signal, temporal portions which belong to diastolic phases of a heart. The processing system is configured to set an output signal of the apparatus to express presence of cardiac abnormality based on a result of a comparison between the indicator quantity and a threshold value.

ES2607721B2 (es)* 2015-10-02 2019-07-04 Univ Catalunya Politecnica Método y aparato para estimar el tiempo de tránsito del pulso aórtico a partir de intervalos temporales medidos entre puntos fiduciales del balistocardiograma