Novel effects of acute COVID-19 on cardiac mechanical function: Two case studies.

The spread of the novel coronavirus 2019 (COVID-19) has caused a global pandemic. The disease has spread rapidly, and research shows that COVID-19 can induce long-lasting cardiac damage. COVID-19 can result in elevated cardiac biomarkers indicative of acute cardiac injury, and research utilizing echocardiography has shown that there is mechanical dysfunction in these patients as well, especially when observing the isovolumic, systolic, and diastolic portions of the cardiac cycle. The purpose of this study was to present two case studies on COVID-19 positive patients who had their cardiac mechanical function assessed every day during the acute period to show that cardiac function in these patients was altered, and the damage occurring can change from day-to-day. Participant 1 showed compromised cardiac function in the systolic time, diastolic time, isovolumic time, and the calculated heart performance index (HPI), and these impairments were sustained even 23 days post-symptom onset. Furthermore, Participant 1 showed prolonged systolic periods that lasted longer than the diastolic periods, indicative of elevated pulmonary artery pressure. Participant 2 showed decreases in systole and consequently, increases in HPI during the 3 days post-symptom onset, and these changes returned to normal after day 4. These results showed that daily observation of cardiac function can provide detailed information about the overall mechanism by which cardiac dysfunction is occurring and that COVID-19 can induce cardiac damage in unique patterns and thus can be studied on a case-by-case basis, day-to-day during infection. This could allow us to move toward more personalized cardiovascular medical treatment.

Detection of magnetic tracers with Mx atomic magnetometer for application to blood velocimetry.

In the new generation of blood velocimeter systems, considerable attention has been paid to atomic magnetometers due to their high resolution and high sensitivity for detection of magnetic tracers. Passing the magnetic tracers adjacent to the atomic magnetometer produces a spike-like signal, the shape of which depends on the position of the tracer, as well as its velocity and orientation. The present study aimed to evaluate the effect of abrupt variations in the instantaneous velocity of the magnetic tracer on the magnetometer response compare to constant velocity. Modeling the magnetic tracer as a dipole moment indicated that the velocity dependence of the magnetic field and local magnetic field gradient associated with moving magnetic tracer cause the spike-like signal to go out of symmetry in the case of variable velocity. Based on the experimental results, any instantaneous variation in tracer velocity leads to shrinkage in the signal width. The behavior has been studied for both magnetic microwire with variable instantaneous velocity and magnetic droplets in stenosis artery phantom. In addition, the position of the tracer could be detected by following the shrinkage behavior which may occur on the peak, valley, or both. These advantageous outcomes can be applied for high sensitivity diagnosis of arterial stenosis.

A Real-Time Blood Flow Measurement Device for Patients with Peripheral Artery Disease.

PURPOSE: To evaluate the feasibility of a new optical device that measures peripheral blood flow as a diagnostic and monitoring tool for patients with peripheral artery disease (PAD). MATERIALS AND METHODS: In this prospective study, 167 limbs of 90 patients (mean age, 76 y; 53% men) with suspected PAD were evaluated with the FlowMet device, which uses a new type of dynamic light-scattering technology to assess blood flow in real time. Measurements of magnitude and phasicity of blood flow were combined into a single-value flow-waveform score and compared vs ankle-brachial index (ABI), toe-brachial index (TBI), and clinical presentation of patients per Rutherford category (RC). Receiver operating characteristic curves were constructed to predict RC. Area under the curve (AUC), sensitivity, and specificity were compared among flow-waveform score, ABI, and TBI. RESULTS: Qualitatively, the FlowMet waveforms were analogous to Doppler velocity measurements, and degradation of waveform phasicity and amplitude were observed with increasing PAD severity. Quantitatively, the flow, waveform, and composite flow-waveform scores decreased significantly with decreasing TBI. In predicting RC ≥ 4, the flow-waveform score (AUC = 0.83) showed a linear decrease with worsening patient symptoms and power comparable to that of TBI (AUC = 0.82) and better than that of ABI (AUC = 0.71). Optimal sensitivity and specificity pairs were found to be 56%/83%, 72%/81%, and 89%/74% for ABI, TBI, and flow-waveform score, respectively. CONCLUSIONS: The technology tested in this pilot study showed a high predictive value for diagnosis of critical limb ischemia. The device showed promise as a diagnostic tool capable of providing clinical feedback in real time.

Assessment of the sublingual microcirculation with the GlycoCheck system: Reproducibility and examination conditions.

BACKGROUND: The glycocalyx is an extracellular layer lining the lumen of the vascular endothelium, protecting the endothelium from shear stress and atherosclerosis and contributes to coagulation, immune response and microvascular perfusion. The GlycoCheck system estimates glycocalyx' thickness in vessels under the tongue from perfused boundary region (PBR) and microvascular perfusion (red blood cell (RBC) filling) via a camera and dedicated software. OBJECTIVES: Evaluating reproducibility and influence of examination conditions on measurements with the GlycoCheck system. METHODS: Open, randomised, controlled study including 42 healthy smokers investigating day-to-day, side-of-tongue, inter-investigator variance, intraclass-correlation (ICC) and influence of examination conditions at intervals from 0-180 minutes on PBR and RBC filling. RESULTS: Mean (SD) age was 24.9 (6.1) years, 52% were male. There was no significant intra- or inter-investigator variation for PBR or RBC filling nor for PBR for side-of-tongue. A small day-to-day variance was found for PBR (0.012µm, p = 0.007) and RBC filling (0.003%, p = 0.005) and side-of-tongue, RBC filling (0.025%, p = 0.009). ICC was modest but highly improved by increasing measurements. Small significant influence of cigarette smoking (from 40-180 minutes), high calorie meal intake and coffee consumption was found. The latter two peaking immediately and tapering off but remained significant up to 180 minutes, highest PBR changes for the three being 0.042µm (p<0.05), 0.183µm (p<0.001) and 0.160µm (p<0.05) respectively. CONCLUSIONS: Measurements with the GlycoCheck system have a moderate reproducibility, but highly increases with multiple measurements and a small day-to-day variability. Smoking, meal and coffee intake had effects up to 180 minutes, abstinence is recommended at least 180 minutes before GlycoCheck measurements. Future studies should standardise conditions during measurements.

Multimodal Device and Computer Algorithm-Based Monitoring of Pancreatic Microcirculation Profiles In Vivo.

OBJECTIVES: Pancreatic microcirculation has an essential role in orchestrating pancreatic homeostasis. Inherent complexity and technological limitation lead to interobserver variability and 1-sided microcirculatory data. Here, we introduce a multimodal device and computer algorithm-based platform for monitoring and visualizing integrated pancreatic microcirculation profiles. METHODS: After anesthetizing and exposing pancreas tissue of BALB/c mice, probes of Oxygen to See, Microx TX3, and MoorVMS-LDF2 were positioned at pancreas in situ to capture the pancreatic microcirculatory oxygen (hemoglobin oxygen saturation, relative amount of hemoglobin, and partial oxygen pressure) and microhemodynamic data (microvascular blood perfusion and velocity). To assess and visualize pancreatic microcirculation profiles, raw data of pancreatic microcirculation profiles were processed and transformed using interquartile range and min-max normalization by Python and Apache ECharts. RESULTS: The multimodal device-based platform was established and 3-dimensional microcirculatory modules were constructed. Raw data sets of pancreatic microcirculatory oxygen and microhemodynamic were collected. The outlier of data set was adjusted to the boundary value and raw data set was preprocessed. Normalized pancreatic microcirculation profiles were integrated into the 3-dimensional histogram and scatter modules, respectively. The 3-dimensional modules of pancreatic microcirculation profiles were then generated. CONCLUSIONS: We established a multimodal device and computer algorithm-based monitoring platform for visualizing integrated pancreatic microcirculation profiles.

2020 Canadian Cardiovascular Society/Canadian Heart Rhythm Society Position Statement on the Management of Ventricular Tachycardia and Fibrillation in Patients With Structural Heart Disease.

This Canadian Cardiovascular Society position statement is focused on the management of sustained ventricular tachycardia (VT) and ventricular fibrillation (VF) that occurs in patients with structural heart disease (SHD), including previous myocardial infarction, dilated cardiomyopathy, and other forms of nonischemic cardiomyopathy. This patient population is rapidly increasing because of advances in care and improved overall survival of patients with all forms of SHD. In this position statement, the acute and long-term management of VT/VF are outlined, and the many unique aspects of care in this population are emphasized. The initial evaluation, acute therapy, indications for chronic suppressive therapy, choices of chronic suppressive therapy, implantable cardioverter-defibrillator programming, alternative therapies, and psychosocial care are reviewed and recommendations for optimal care are provided. The target audience for this statement includes all health professionals involved in the continuum of care of patients with SHD and VT/VF.

Fragmented QRS complex in patients with systemic lupus erythematosus at the time of diagnosis and its relationship with disease activity.

OBJECTIVE: Cardiovascular disease is an important contributor to the mortality rate of patients with systemic lupus erythematosus (SLE), which is related to SLE disease activity. Fragmented QRS (fQRS) complexes, defined by additional spikes in the QRS complex, are useful for identifying myocardial scars on electrocardiography and can be an independent predictor of cardiac events. We aimed to assess the relationship between disease activity in patients with SLE and fQRS at the time of diagnosis. METHODS: Forty-four patients with SLE were included. Patients with cardiac diseases, other rheumatic diseases, and prior treatment at the time of electrocardiography measurement were excluded. The appearance of fQRS represented exposure. The primary outcome was SLE Disease Activity Index 2000 (SLEDAI-2K). Multiple regression analysis was conducted to assess the association between fQRS and SLEDAI-2K adjusted for age, sex, and time from the estimated onset date to the date of diagnosis. RESULTS: Among patients with SLE at diagnosis, 26 (59.1%) had fQRS. The median SLEDAI-2K was 18 (interquartile range [IQR], 12-22) and 9 (IQR, 8-15) in the fQRS(+) and fQRS(-) groups, respectively. SLEDAI-2K was significantly higher in the fQRS(+) group than in the fQRS(-) group (regression coefficient, 2.69; 95% confidence interval, 0.76-4.61; p = 0.008). CONCLUSION: Our results suggested that fQRS(+) patients with SLE had high disease activity. fQRS could likely detect subclinical myocardial involvement in patients with SLE and predict long-term occurrence of cardiac events.

Measurement reproducibility of slice-interleaved T1 and T2 mapping sequences over 20 months: A single center study.

BACKGROUND: Quantifying reproducibility of native T1 and T2 mapping over a long period (> 1 year) is necessary to assess whether changes in T1 and T2 over repeated sessions in a longitudinal study are associated with variability due to underlying tissue composition or technical confounders. OBJECTIVES: To carry out a single-center phantom study to 1) investigate measurement reproducibility of slice-interleaved T1 (STONE) and T2 mapping over 20 months, 2) quantify sources of variability, and 3) compare reproducibility and measurements against reference spin-echo measurements. METHODS: MR imaging was performed on a 1.5 Tesla Philips Achieva scanner every 2-3 weeks over 20 months using the T1MES phantom. In each session, slice-interleaved T1 and T2 mapping was repeated 3 times for 5 slices, and maps were reconstructed using both 2-parameter and 3-parameter fit models. Reproducibility between sessions, and repeatability between repetitions and slices were evaluated using coefficients of variation (CV). Different sources of variability were quantified using variance decomposition analysis. The slice-interleaved measurement was compared to the spin-echo reference and MOLLI. RESULTS: Slice-interleaved T1 had excellent reproducibility and repeatability with a CV < 2%. The main sources of T1 variability were temperature in 2-parameter maps, and slice in 3-parameter maps. Superior between-session reproducibility to the spin-echo T1 was shown in 2-parameter maps, and similar reproducibility in 3-parameter maps. Superior reproducibility to MOLLI T1 was also shown. Similar measurements to the spin-echo T1 were observed with linear regression slopes of 0.94-0.99, but slight underestimation. Slice-interleaved T2 showed good reproducibility and repeatability with a CV < 7%. The main source of T2 variability was slice location/orientation. Between-session reproducibility was lower than the spin-echo T2 reference and showed good measurement agreement with linear regression slopes of 0.78-1.06. CONCLUSIONS: Slice-interleaved T1 and T2 mapping sequences yield excellent long-term reproducibility over 20 months.

Deep learning for cardiovascular medicine: a practical primer.

Deep learning (DL) is a branch of machine learning (ML) showing increasing promise in medicine, to assist in data classification, novel disease phenotyping and complex decision making. Deep learning is a form of ML typically implemented via multi-layered neural networks. Deep learning has accelerated by recent advances in computer hardware and algorithms and is increasingly applied in e-commerce, finance, and voice and image recognition to learn and classify complex datasets. The current medical literature shows both strengths and limitations of DL. Strengths of DL include its ability to automate medical image interpretation, enhance clinical decision-making, identify novel phenotypes, and select better treatment pathways in complex diseases. Deep learning may be well-suited to cardiovascular medicine in which haemodynamic and electrophysiological indices are increasingly captured on a continuous basis by wearable devices as well as image segmentation in cardiac imaging. However, DL also has significant weaknesses including difficulties in interpreting its models (the 'black-box' criticism), its need for extensive adjudicated ('labelled') data in training, lack of standardization in design, lack of data-efficiency in training, limited applicability to clinical trials, and other factors. Thus, the optimal clinical application of DL requires careful formulation of solvable problems, selection of most appropriate DL algorithms and data, and balanced interpretation of results. This review synthesizes the current state of DL for cardiovascular clinicians and investigators, and provides technical context to appreciate the promise, pitfalls, near-term challenges, and opportunities for this exciting new area.

Hand Perfusion in Patients with Physiological or Pathological Allen's Tests.

BACKGROUND: The Allen test (AT) is a widely used clinical tool for the preoperative assessment of sufficient dual vessel hand perfusion although the impact of a pathological AT on tissue perfusion of the hand is not entirely clear. This study reveals perfusion changes of the hand in patients with pathological and physiological AT after terminating the dual blood supply. METHODS: Patients were distributed into 2 groups (physiological and pathological AT) that each contained 25 members. Perfusion of the thumb, middle, and small fingers was measured with a laser Doppler based ("oxygen-to-see" [O2C]) device. A steady state was measured and also values at 1, 3, 5, and 10 minutes after radial occlusion were measured. RESULTS: In patients with a physiological AT, only 1 out of 18 values differed significantly from the steady state measurements after 10 minutes, whereas patients with a pathological AT showed significant alterations in 8 out of 18 values. Oxygen saturation of the superficial and deep tissues appeared to be significantly worse in patients with a pathological AT. CONCLUSION: Patients with a pathological AT suffered significantly more from the loss of dual hand perfusion than patients with a physiological AT. Patients with a pathological AT need more time to compensate for the altered perfusion pattern.

Painless local pressure application to test microvascular reactivity to ischemia.

BACKGROUND: Forearm cutaneous blood flux (CBF) measurement with post-occlusive reactive hyperemia (PORH) is uncomfortable and may not be devoid of risks. We aimed to investigate post-compression reactive hyperemia (PCRH) with a custom-made indenter that was designed to be easily used routinely by inexperienced observers. METHODS: Medical students evaluated PCRH with 1- to 4-min pressure applications of 16 to 34 kPa and PORH with 3-min forearm cuff occlusion using laser speckle contrast imaging in 15 healthy volunteers. Participants were asked to quantify their discomfort with a visual analogue scale (VAS) of 10 cm. Total ischemia (ISCH) was quantified by the product of CBF during ischemia and ischemia duration (min). We subtracted the CBF changes in the skin from a reference ipsilateral (PCRH) or contralateral (PORH) non-stimulated area. RESULTS: The average VAS was 1.0 for PCRH vs. 6.0 for PORH (p < 0.001). A strong linear relationship between ISCH and peak PCRH (r2 = 0.915, p < 0.001) was noted. Peak PORH values (63.9 laser perfusion units (LPU)) were significantly lower than all values of the 3-min PCRH (72.6 LPU), including the one obtained with 16 kPa. CONCLUSION: Inexperienced observers could test microvascular reactivity with PCRH without inducing the discomfort that is typically experienced with PORH. Further, PCRH elicits a higher peak response to ischemia compared with PORH. This extremely simple method could influence a broad spectrum of routine cutaneous microcirculation investigations, especially when a painful approach is particularly inadequate or if the patient is fragile. CLINICAL TRIAL REGISTRATION: NCT02861924.

Investigating the ability of non-invasive measures of cardiac output to detect a reduction in blood volume resulting from venesection in spontaneously breathing subjects.

BACKGROUND: Monitoring cardiac output (CO) in shocked patients provides key etiological information and can be used to guide fluid resuscitation to improve patient outcomes. Previously this relied on invasive monitoring, restricting its use in the Emergency Department (ED) setting. The development of non-invasive devices (such as LiDCOrapidv2 with CNAP™ and USCOM 1A), and ultrasound based measurements (Transthoracic echocardiography, inferior vena cava collapsibility index (IVCCI), carotid artery blood flow (CABF) and carotid artery corrected flow time (FTc)) enables stroke volume (SV) and CO to be measured non-invasively in the ED. We investigated the ability of these techniques to detect a change in CO resulting from a 500 ml reduction in circulating blood volume (CBV) following venesection in spontaneously breathing subjects. Additionally, we investigated if using incentive spirometry to standardise inspiratory effort improved the accuracy of IVC based measurements in spontaneously breathing subjects. METHODS: We recorded blood pressure, heart rate, IVCCI, CABF, FTc, transthoracic echocardiographic (TTE) SV and CO, USCOM 1A SV and CO, LIDCOrapidv2 SV, CO, Stroke volume variation (SVV) and pulse pressure variation (PPV) in 40 subjects immediately before and after venesection. The Log-Odds and coefficient of variation of the difference between pre- and post-venesection values for each technique were used to compare their ability to consistently detect CO changes resulting from a reduction in CBV resulting from venesection. RESULTS: TTE consistently detected a reduction in CO associated with venesection with an average decrease in measured CO of 0.86 L/min (95% CI 0.61 to 1.12) across subjects. None of the other investigated techniques changed in a consistent manner following venesection. The use of incentive spirometry improved the consistency with which IVC ultrasound was able to detect a reduction in CBV. CONCLUSIONS: In a population of spontaneously breathing patients, TTE is able to consistency detect a reduction in CO associated with venesection.

High-Resolution Seismocardiogram Acquisition and Analysis System.

Several devices and measurement approaches have recently been developed to perform ballistocardiogram (BCG) and seismocardiogram (SCG) measurements. The development of a wireless acquisition system (hardware and software), incorporating a novel high-resolution micro-electro-mechanical system (MEMS) accelerometer for SCG and BCG signals acquisition and data treatment is presented in this paper. A small accelerometer, with a sensitivity of up to 0.164 µs/µg and a noise density below 6.5 µg/ Hz is presented and used in a wireless acquisition system for BCG and SCG measurement applications. The wireless acquisition system also incorporates electrocardiogram (ECG) signals acquisition, and the developed software enables the real-time acquisition and visualization of SCG and ECG signals (sensor positioned on chest). It then calculates metrics related to cardiac performance as well as the correlation of data from previously performed sessions with echocardiogram (ECHO) parameters. A preliminarily clinical study of over 22 subjects (including healthy subjects and cardiovascular patients) was performed to test the capability of the developed system. Data correlation between this measurement system and echocardiogram exams is also performed. The high resolution of the MEMS accelerometer used provides a better signal for SCG wave recognition, enabling a more consistent study of the diagnostic capability of this technique in clinical analysis.

Newer technologies for detection of atrial fibrillation.

Atrial fibrillation is a common arrhythmia that is associated with increased risk of stroke, which can be reduced with appropriate anticoagulation treatment. However, it remains underdiagnosed in contemporary clinical practice using conventional detection methods, resulting in missed opportunities to implement appropriate treatment. Newer technologies developed in recent years can potentially enhance the detection of atrial fibrillation and overcome certain limitations of the conventional methods. However, uncertainties remain about their use and the significance of atrial fibrillation detected by some of these newer technologies. This review examines the evidence supporting the use of some of these technologies and evaluates their applications in certain clinical scenarios.

Brief cardiovascular imaging with pocket-size ultrasound devices improves the accuracy of the initial assessment of suspected pulmonary embolism.

Pulmonary embolism onset is frequently neglected due to the non-specific character of its symptoms. Pocket-size imaging devices (PSID) present an opportunity to implement imaging diagnostics into conventional physical examination. The aim of this study was to test the hypothesis that supplementation of the initial bedside assessment of patients with suspected pulmonary embolism (PE) with four-point compression venous ultrasonography (CUS) and right ventricular size assessment with the use of PSID equipped with dual probe could positively influence the accuracy of clinical predictions. A single-centre, prospective analysis was conducted on 100 patients (47 men, mean age 68 ± 13 years) with suspected PE. Clinical assessment on the basis of Wells and revised Geneva score and physical examination were supplemented with CUS and RV measurements by PSID. The mean time of PSID scanning was 4.9 ± 0.8 min and was universally accepted by the patients. Fifteen patients had deep venous thrombosis and RV enlargement was observed in 59 patients. PE was confirmed in 24 patients. If the both CUS was positive and RV enlarged, the specificity was 100% and sensitivity 54%, ROC AUC 0.771 [95% CI 0.68-0.85]. The Wells rule within our study population had the specificity of 86% and sensitivity of 67%, ROC AUC 0.776 (95% CI 0.681-0.853, p < 0.0001). Similar values calculated for the revised Geneva score were as follows: specificity 58% and sensitivity 63%, ROC AUC 0.664 (95% CI 0.563-0.756, p = 0.0104). Supplementing the revised Geneva score with additional criteria of CUS result and RV measurement resulted in significant improvement of diagnostic accuracy. The difference between ROC AUCs was 0.199 (95% Cl 0.0893-0.308, p = 0.0004). Similar modification of Wells score increased ROC AUC by 0.133 (95% CI 0.0443-0.223, p = 0.0034). Despite the well-acknowledged role of the PE clinical risk assessment scores the diagnostic process may benefit from the addition of basic bedside ultrasonographic techniques.

Comparative evaluation of Plateletworks, Multiplate analyzer and Platelet function analyzer-200 in cardiology patients.

The objective of this study was to comparatively evaluate three commercial whole-blood platelet function analyzer systems: Platelet Function Analyzer-200 (PFA; Siemens Canada, Mississauga, Ontario, Canada), Multiplate analyzer (MP; Roche Diagnostics International Ltd., Rotkreuz, Switzerland), and Plateletworks Combo-25 kit (PLW; Helena Laboratories, Beaumont, TX, USA). Venipuncture was performed on 160 patients who visited a department of cardiology. Pairwise agreement among the three platelet function assays was assessed using Cohen's kappa coefficient and percent agreement within the reference limit. Kappa values with the same agonists were poor between PFA-collagen (COL; agonist)/adenosine diphosphate (ADP) and MP-ADP (-0.147), PFA-COL/ADP and PLW-ADP (0.089), MP-ADP and PLW-ADP (0.039), PFA-COL/ADP and MP-COL (-0.039), and between PFA-COL/ADP and PLW-COL (-0.067). Nonetheless, kappa values for the same assay principle with a different agonist were slightly higher between PFA-COL/ADP and PFA-COL/EPI (0.352), MP-ADP and MP-COL (0.235), and between PLW-ADP and PLW-COL (0.247). The range of percent agreement values was 38.7% to 73.8%. Therefore, various measurements of platelet function by more than one method were needed to obtain a reliable interpretation of platelet function considering low kappa coefficient and modest percent agreement rates among 3 different platelet function tests.

Magnetic particle imaging for radiation-free, sensitive and high-contrast vascular imaging and cell tracking.

Magnetic particle imaging (MPI) is an emerging ionizing radiation-free biomedical tracer imaging technique that directly images the intense magnetization of superparamagnetic iron oxide nanoparticles (SPIOs). MPI offers ideal image contrast because MPI shows zero signal from background tissues. Moreover, there is zero attenuation of the signal with depth in tissue, allowing for imaging deep inside the body quantitatively at any location. Recent work has demonstrated the potential of MPI for robust, sensitive vascular imaging and cell tracking with high contrast and dose-limited sensitivity comparable to nuclear medicine. To foster future applications in MPI, this new biomedical imaging field is welcoming researchers with expertise in imaging physics, magnetic nanoparticle synthesis and functionalization, nanoscale physics, and small animal imaging applications.