Levine, Benjamin D.

Heart rate variability (HRV) is a widely utilized approach for investigating cardiovascular health and human performance. Methodological approaches, analyses, and interpretations of HRV can vary extensively, and scientific debates on HRV reliability and utility remain. These debates have been amplified in recent years by the rapid growth and ubiquity of wearable devices, and their incorporation into scientific research studies. The present guidelines paper takes an evidence-based approach to propose more consistent and rigorous measurement and interpretation of HRV within human cardiovascular research and application. First, HRV has some utility as a cardiovascular risk stratification tool, but is not appropriate to employ as a specific marker of cardiac sympathetic outflow or sympathovagal balance. While time-domain and spectral analysis can more accurately reflect respiratory modulation of cardiac vagal (parasympathetic) activity, caution is necessary to avoid overinterpretation, particularly with respect to the concept of “vagal tone”. Numerous experimental, demographic, and environmental factors influence HRV assessment, interpretation, and reliability. Specifically, it is critical to account for non-modifiable (age, sex, race/ethnicity, etc.) and modifiable (i.e., exercise, physical fitness, etc.) factors within participant samples. Furthermore, technical approaches such as the HRV input signal (e.g., electrocardiography vs. photoplethysmography), length of recording, location of recordings (i.e., laboratory vs. field), respiratory rate and depth, and analytical approaches (i.e., time vs. frequency domain) can all impact rigor, reliability, and study interpretations. Finally, with respect to the rapid advancements of HRV assessment using wearable technology, investigators should interpret and contextualize findings within the limitations outlined in this guideline review.

Exercise and physical activity are recognized as essential tools to optimize fitness and longevity, improve overall health, and reduce the risk of cardiovascular disease and other major comorbidities. However, there are inherent risks associated with participation in sports and exercise, regardless of the level of competition or skill required. As such, there is a need for cardiologists to understand the unique aspects of competitive and recreational athletics, as well as sport and exercise science, as it relates to overall heart health and cardiovascular risk. In this article, we provide an overview of the essential aspects of sports and exercise cardiology. We describe the roles and responsibilities of a sports and exercise cardiologist as a member of a comprehensive team of experts who provide care of athletes at all levels of sport, emphasize the importance of risk stratification and prevention of sudden cardiac arrest, the role of exercise for maintaining and optimizing overall health in the general population, describe the growing field of sports electrophysiology and also discuss unique aspects of sports cardiology applied to environmental health and care of the tactical athlete. Knowledge gaps and directions for future clinical and research investigation are reviewed.

In this case series study, pulmonary artery systolic, diastolic, and mean pressures of 2 participants with obesity and heart failure with preserved ejection fraction were measured at zero gravity during parabolic flight to assess the effect of external constraint on left ventricular filling pressures.

Abstract Regular physical activity decreases the risk of cardiovascular disease, type II diabetes, obesity, certain cancers, and all-cause mortality. Nevertheless, there is mounting evidence that extreme exercise behaviors may be detrimental to human health. This review collates several decades of literature on the physiology and pathophysiology of ultra-marathon running, with emphasis on the cardiorespiratory implications. Herein, we discuss the prevalence and clinical significance of postrace decreases in lung function and diffusing capacity, respiratory muscle fatigue, pulmonary edema, biomarkers of cardiac injury, left/right ventricular dysfunction, and chronic myocardial remodeling. The aim of this article is to inform risk stratification for ultra-marathon and to edify best practice for personnel overseeing the events ( i.e. , race directors and medics).

SummaryBackgroundHyperbaric oxygen has been reported to improve disease activity in hospitalised ulcerative colitis (UC) patients.AimTo evaluate dosing strategies with hyperbaric oxygen for hospitalised UC patients.MethodsWe enrolled UC patients hospitalised for acute flares (Mayo score 6‐12). Initially, all patients received 3 days of hyperbaric oxygen at 2.4 atmospheres (90 minutes with two air breaks) in addition to intravenous steroids. Day 3 responders (reduction of partial Mayo score ≥ 2 points and rectal bleeding score ≥ 1 point) were randomised to receive a total of 5 days vs 3 days of hyperbaric oxygen.ResultsWe treated 20 patients with hyperbaric oxygen (75% prior biologic failure). Day 3 response was achieved in 55% (n = 11/20), with significant reductions in stool frequency, rectal bleeding and CRP (P < 0.01). A more significant reduction in disease activity was observed with 5 days vs 3 days of hyperbaric oxygen (P = 0.03). Infliximab or colectomy was required in only three patients (15%) despite a predicted probability of 80% for second‐line therapy. Day 3 hyperbaric oxygen responders were less likely to require re‐hospitalisation or colectomy by 3 months vs non‐responders (0% vs 66%, P = 0.002). No treatment‐related adverse events were observed.ConclusionHyperbaric oxygen appears to be effective for optimising response to intravenous steroids in UC patients hospitalised for acute flares, with low rates of re‐hospitalisation or colectomy at 3 months. An optimal clinical response is achieved with 5 days of hyperbaric oxygen. Larger phase 3 trials are needed to confirm efficacy and obtain labelled approval.

Background— Hemodynamic assessment after volume challenge has been proposed as a way to identify heart failure with preserved ejection fraction. However, the normal hemodynamic response to a volume challenge and how age and sex affect this relationship remain unknown. Methods and Results— Sixty healthy subjects underwent right heart catheterization to measure age- and sex-related normative responses of pulmonary capillary wedge pressure and mean pulmonary arterial pressure to volume loading with rapid saline infusion (100–200 mL/min). Hemodynamic responses to saline infusion in heart failure with preserved ejection fraction (n=11) were then compared with those of healthy young (<50 years of age) and older (≥50 years of age) subjects. In healthy subjects, pulmonary capillary wedge pressure increased from 10±2 to 16±3 mm Hg after ~1 L and to 20±3 mm Hg after ~2 L of saline infusion. Older women displayed a steeper increase in pulmonary capillary wedge pressure relative to volume infused (16±4 mm Hg·L −1 ·m 2 ) than the other 3 groups ( P ≤0.019). Saline infusion resulted in a greater increase in mean pulmonary arterial pressure relative to cardiac output in women compared with men regardless of age. Subjects with heart failure with preserved ejection fraction exhibited a steeper increase in pulmonary capillary wedge pressure relative to infused volume (25±12 mm Hg·L −1 ·m 2 ) than healthy young and older subjects ( P ≤0.005). Conclusions— Filling pressures rise significantly with volume loading, even in healthy volunteers. Older women and patients with heart failure with preserved ejection fraction exhibit the largest increases in pulmonary capillary wedge pressure and mean pulmonary arterial pressure.