Heart Rate Variability Measurement through a Smart Wearable Device: Another Breakthrough for Personal Health Monitoring?

Heart rate variability (HRV) is a measurement of the fluctuation of time between each heartbeat and reflects the function of the autonomic nervous system. HRV is an important indicator for both physical and mental status and for broad-scope diseases. In this review, we discuss how wearable devices can be used to monitor HRV, and we compare the HRV monitoring function among different devices. In addition, we have reviewed the recent progress in HRV tracking with wearable devices and its value in health monitoring and disease diagnosis. Although many challenges remain, we believe HRV tracking with wearable devices is a promising tool that can be used to improve personal health.

Radiation exposure during distal and traditional radial coronary angiography and percutaneous coronary intervention: a meta-analysis of randomized controlled trials.

OBJECTIVES: Previous studies show that the distal transradial approach (dTRA) is safe and effective for coronary angiography and percutaneous coronary intervention. However, the effect of dTRA on radiation exposure in the catheterization laboratory has not been characterized. The authors analyzed the available literature to compare the radiation exposure associated with dTRA vs the traditional radial approach (TRA). METHODS: A systematic review and meta-analysis of the scientific literature was conducted by using relevant terms to search the PubMed, Embase, and Cochrane Library databases from their inception until October 13, 2022, to identify randomized controlled trials (RCTs) comparing dTRA with TRA. The primary outcome was radiation exposure reported as fluoroscopy time, air kerma, or kerma-dose product. The standard mean difference (SMD) and its 95% confidence interval were used to summarize continuous variables. Random effect and meta-regression also were used for analyses. RESULTS: Among 484 studies identified, 7 were RCTs, with a total of 3427 patients (1712 dTRA, 1715 TRA). No difference was found between dTRA and TRA in radiation exposure quantified as fluoroscopy time (SMD -0.10 [-0.36, 0.15], P=.43) or air kerma (SMD -0.31 [-0.74, 0.13], P=.17). The overall estimate favored lower kerma-area product in the TRA (SMD 0.19 [0.08, 0.30], P=.0006). Meta-regression showed no correlation between fluoroscopy time and year of publication. CONCLUSIONS: Compared with TRA, dTRA was associated with significantly greater radiation exposure per the kerma-area product during interventional cardiology procedures, with no differences in fluoroscopy time and air kerma.

Evaluation of large animal models for preclinical studies of heart failure with preserved ejection fraction using clinical score systems.

Heart failure with preserved ejection fraction (HFpEF) is characterized by a complex, heterogeneous spectrum of pathologic features combined with average left ventricular volume and diastolic dysfunction. HFpEF is a significant public health problem associated with high morbidity and mortality rates. Currently, effective treatments for HFpEF represent the greatest unmet need in cardiovascular medicine. A lack of an efficient preclinical model has hampered the development of new devices and medications for HFpEF. Because large animal models have similar physiologic traits as humans and appropriate organ sizes, they are the best option for limiting practical constraints. HFpEF is a highly integrated, multiorgan, systemic disorder requiring a multipronged investigative approach. Here, we review the large animal models of HFpEF reported to date and describe the methods that have been used to create HFpEF, including surgery-induced pressure overloading, medicine-induced pressure overloading, and diet-induced metabolic syndrome. In addition, for the first time to our knowledge, we use two established clinical HFpEF algorithms (HFA-PEFF and H2FPEF scores) to evaluate the currently available large animal models. We also discuss new technologies, such as continuous remote pressure monitors and inflatable aortic cuffs, as well as how the models could be improved. Based on current progress and our own experience, we believe an efficient large animal model of HFpEF should simultaneously encompass multiple pathophysiologic factors, along with multiorgan dysfunction. This could be fully evaluated through available methods (imaging, blood work). Although many models have been studied, only a few studies completely meet clinical score standards. Therefore, it is critical to address the deficiencies of each model and incorporate novel techniques to establish a more reliable model, which will help facilitate the understanding of HFpEF mechanisms and the development of a treatment.

Early Changes in Acute Myocardial Infarction in Pigs: Achieving Early Detection with Wearable Devices.

We examined the changes in variables that could be recorded on wearable devices during the early stages of acute myocardial infarction (AMI) in an animal model. Early diagnosis of AMI is important for prognosis; however, delayed diagnosis is common because of patient hesitation and lack of timely evaluations. Wearable devices are becoming increasingly sophisticated in the ability to track indicators. In this study, we retrospectively reviewed the changes in four variables during AMI in a pig model to assess their ability to help predict AMI onset. AMI was created in 33 pigs by 90-min balloon occlusion of the left anterior descending artery. Blood pressure, EKG, and lactate and cardiac troponin I levels were recorded during the occlusion period. Blood pressure declined significantly within 15 min after balloon inflation (mean arterial pressure, from 61 ± 8 to 50 ± 8 mmHg) and remained at this low level. Within 5 min of balloon inflation, the EKG showed ST-elevation in precordial leads V1-V3. Blood lactate levels increased gradually after occlusion and peaked at 60 min (from 1.48 to 2.53 mmol/L). The continuous transdermal troponin sensor demonstrated a gradual increase in troponin levels over time. Our data suggest that significant changes in key indicators (blood pressure, EKG leads V1-V3, and lactate and troponin levels) occurred at the onset of AMI. Monitoring of these variables could be used to develop an algorithm and alert patients early at the onset of AMI with the help of a wearable device.

A Robust Percutaneous Myocardial Infarction Model in Pigs and Its Effect on Left Ventricular Function.

In this study, we created a reproducible myocardial infarction (MI) model in pigs characterized by a low mortality rate and significant changes in left ventricular function. After administering an arrhythmia prevention regimen, we created a 90-min balloon-induced percutaneous MI in 42 pigs below the first diagonal branch (D1) of the left anterior descending artery. Echocardiograms were performed before and 14 days after MI induction. Pigs with a > 30% decrease in left ventricular ejection fraction (LVEF) underwent electrophysiological mapping by the NOGA system. Our mortality rate was 4.8%. The incidence of ventricular fibrillation (VF) was 28.6%; all VF events were successfully resuscitated. At day 14, echocardiography and NOGA mapping confirmed transmural scar. LVEF decreased 41% from baseline. Radial and circumferential strain significantly decreased in the LAD distal to D1, and the LV showed dyssynchrony. An anti-arrhythmia regimen decreased mortality significantly, and our model induced dramatic functional changes. The basic procedures of the model included an arrhythmia prevention protocol and myocardial infarction creation, which effectively decreased mortality and provided a robust change in left ventricular (LV) function after 14 days.

Factor Xa inhibitors in patients with continuous-flow left ventricular assist devices.

OBJECTIVE: Warfarin is standard anticoagulation therapy for patients with a continuous-flow left ventricular assist device (CF-LVAD). However, warfarin requires regular monitoring and dosage adjustments and fails for many patients, causing thromboembolic and bleeding events. Factor Xa inhibitors have been shown to be noninferior to warfarin in preventing strokes and are associated with less intracranial hemorrhage in patients with atrial fibrillation. We evaluated treatment safety and effectiveness in CF-LVAD patients who switched from warfarin to a factor Xa inhibitor (apixaban or rivaroxaban) after warfarin failure. METHODS: This was a retrospective, single-center study of patients treated between 2008 and 2018. We assessed the occurrence of stroke, non-central nervous system (CNS) embolism, pump thrombosis, and major gastrointestinal bleeding and intracranial hemorrhage during therapy. RESULTS: We identified seven patients: five were male, the average body mass index was 30 kg/m2, and average age was 56 years. Preimplantation comorbidities included hypertension (all patients) and diabetes mellitus, ischemic cardiomyopathy, atrial fibrillation, and previous myocardial infarction (four patients each). Overall, patients received warfarin for 3968 days and apixaban/rivaroxaban for 1459 days. The warfarin group was within the therapeutic INR range (2.0-3.0) 30% of the time. Complication rates did not differ between warfarin and apixaban/rivaroxaban: strokes, 0.20 vs none, non-CNS embolism, 0.54 vs none; pump thrombosis, 0.27 vs none; major gastrointestinal bleeding, 0.20 vs 0.50; intracranial hemorrhage, 0.13 vs none. CONCLUSIONS: Factor Xa inhibitors may be viable treatment options for CF-LVAD patients for whom warfarin therapy has failed. Large prospective studies are necessary to confirm these results.