Pulmonary gas exchange in relation to exercise pulmonary hypertension in patients with heart failure with preserved ejection fraction.

Background: Exercise pulmonary hypertension (ePH), defined as a mean pulmonary artery pressure (mPAP)/cardiac output (Qc) slope >3 WU during exercise, is common in patients with heart failure with preserved ejection fraction (HFpEF). However, the pulmonary gas exchange-related effects of an exaggerated ePH (EePH) response are not well-defined, especially in relation to dyspnea on exertion (DOE) and exercise intolerance.

Methods: 48 HFpEF patients underwent invasive (pulmonary and radial artery catheters) constant-load (20W) and maximal incremental cycle testing.

Identifying the Mechanisms of a Peripherally Limited Exercise Phenotype in Patients With Heart Failure With Preserved Ejection Fraction.

Background: We identified peripherally limited patients using cardiopulmonary exercise testing and measured skeletal muscle oxygen transport and utilization during invasive single leg exercise testing to identify the mechanisms of the peripheral limitation.

Methods: Forty-five patients with heart failure with preserved ejection fraction (70±7 years, 27 females) completed seated upright cardiopulmonary exercise testing and were defined as having a (1) peripheral limitation to exercise if cardiac output/oxygen consumption (VO) was elevated (≥6) or 5 to 6 with a stroke volume reserve >50% (n=31) or (2) a central limitation to exercise if cardiac output/VO slope was ≤5 or 5 to 6 with stroke volume reserve <50% (n=14). Single leg knee extension exercise was used to quantify peak leg blood flow (Doppler ultrasound), arterial-to-venous oxygen content difference (femoral venous catheter), leg VO, and muscle oxygen diffusive conductance.

Impaired longitudinal systolic-diastolic coupling and cardiac response to exercise in patients with hypertrophic cardiomyopathy.

Background: In patients with hypertrophic cardiomyopathy (HCM), impaired augmentation of stroke volume and diastolic dysfunction contribute to exercise intolerance. Systolic-diastolic (S-D) coupling characterizes how systolic contraction of the left ventricle (LV) primes efficient elastic recoil during early diastole. Impaired S-D coupling may contribute to the impaired cardiac response to exercise in patients with HCM.

Plasma epinephrine and norepinephrine responses to extreme heat exposures in young and older adults.

Hyperthermia is known as a hyperadrenergic state, yet there is a lack of data on the sympathetic responses to ambient heat stress in humans. Therefore, we investigated the plasma epinephrine and norepinephrine concentrations of healthy young and older adults exposed to 3 h of very hot and dry, as well as hot and humid, heat, both with accompanying activities of daily living. We hypothesized that older adults, compared with young adults, would have augmented increases in epinephrine and norepinephrine concentrations secondary to increased thermal strain.

Sympathetic Neural Control at Rest and During the Cold Pressor Test in Patients With Heart Failure With Preserved Ejection Fraction.

Background: We tested the hypothesis that patients with heart failure with preserved ejection fraction (HFpEF) would have greater muscle sympathetic nerve activity (MSNA) at rest and sympathetic reactivity during a cold pressor test compared with non-heart failure controls. Further, given the importance of the baroreflex modulation of MSNA in the control of blood pressure (BP), we hypothesized that patients with HFpEF would exhibit a reduced sympathetic baroreflex sensitivity.

Methods: Twenty-eight patients with HFpEF and 44 matched controls (mean±SD: 71±8 versus 70±7 years; 9 men/19 women versus 16 men/28 women) were studied.

Attenuated peripheral oxygen extraction and greater cardiac output in women with posttraumatic stress disorder during exercise.

Posttraumatic stress disorder (PTSD) is associated with an increased risk of developing cardiovascular disease, especially in women. Evidence indicates that men with PTSD exhibit lower maximal oxygen uptake (V̇o) relative to controls; however, whether V̇o is blunted in women with PTSD remains unknown. Furthermore, it is unclear what determinants (i.

Randomized Controlled Trial of Moderate- and High-Intensity Exercise Training in Patients With Hypertrophic Cardiomyopathy: Effects on Fitness and Cardiovascular Response to Exercise.

Background Moderate intensity exercise training (MIT) is safe and effective for patients with hypertrophic cardiomyopathy, yet the efficacy of high intensity training (HIT) remains unknown. This study aimed to compare the efficacy of HIT compared with MIT in patients with hypertrophic cardiomyopathy. Methods and Results Patients with hypertrophic cardiomyopathy were randomized to either 5 months of MIT, or 1 month of MIT followed by 4 months of progressive HIT.

Effects of Synchronizing Foot Strike and Cardiac Phase on Exercise Hemodynamics in Patients With Cardiac Resynchronization Therapy: A Within-Subjects Pilot Study to Fine-Tune Cardio-Locomotor Coupling for Heart Failure.

Background: Despite advances in medical and cardiac resynchronization therapy (CRT), individuals with chronic congestive heart failure (CHF) have persistent symptoms, including exercise intolerance. Optimizing cardio-locomotor coupling may increase stroke volume and skeletal muscle perfusion as previously shown in healthy runners. Therefore, we tested the hypothesis that exercise stroke volume and cardiac output would be higher during fixed-paced walking when steps were synchronized with the diastolic compared with systolic portion of the cardiac cycle in patients with CHF and CRT.

Ventilatory limitations in patients with HFpEF and obesity.

Heart failure with preserved ejection fraction (HFpEF) patients have an increased ventilatory demand. Whether their ventilatory capacity can meet this increased demand is unknown, especially in those with obesity. Body composition (DXA) and pulmonary function were measured in 20 patients with HFpEF (69 ± 6 yr;9 M/11 W).

Characterizing regional and global effects of epicardial adipose tissue on cardiac systolic and diastolic function.

Objective: The aim of this retrospective study was to determine whether regional epicardial adipose tissue (EAT) exerts localized effects on adjacent myocardial left ventricular (LV) function.

Methods: Cardiac magnetic resonance imaging (MRI), echocardiography, dual-energy x-ray absorptiometry, and exercise testing were performed in 71 patients with obesity with elevated cardiac biomarkers and visceral fat. Total and regional (anterior, inferior, lateral, right ventricular) EAT was quantified by MRI.

SERCA2a Agonist Effects on Cardiac Performance During Exercise in Heart Failure With Preserved Ejection Fraction.

Background: Impaired ventricular relaxation influences left ventricular pressures during exercise in heart failure with preserved ejection fraction (HFpEF). Sarco/endoplasmic reticulum calcium-adenosine triphosphatase (SERCA2a) facilitates myocardial relaxation by increasing calcium reuptake and is impaired in HFpEF.

Objectives: This study sought to investigate the effects of istaroxime, a SERCA2 agonist, on lusitropic and hemodynamic function during exercise in patients with HFpEF and control subjects.

Reducing Pulmonary Capillary Wedge Pressure During Exercise Exacerbates Exertional Dyspnea in Patients With Heart Failure With Preserved Ejection Fraction: Implications for V˙/Q˙ Mismatch.

Background: The primary cause of dyspnea on exertion in heart failure with preserved ejection fraction (HFpEF) is presumed to be the marked rise in pulmonary capillary wedge pressure during exercise; however, this hypothesis has never been tested directly. Therefore, we evaluated invasive exercise hemodynamics and dyspnea on exertion in patients with HFpEF before and after acute nitroglycerin (NTG) treatment to lower pulmonary capillary wedge pressure.

Research Question: Does reducing pulmonary capillary wedge pressure during exercise with NTG improve dyspnea on exertion in HFpEF?

Study Design And Methods: Thirty patients with HFpEF performed two invasive 6-min constant-load cycling tests (20 W): one with placebo (PLC) and one with NTG.

Cardiac remodeling in well-healed burn survivors after 6 months of unsupervised progressive exercise training.

Aerobic exercise is important in the rehabilitation of individuals with prior burn injuries, but no studies have examined whether adult burn survivors demonstrate cardiac remodeling to long-term aerobic exercise training. In this study, we tested the hypothesis that 6 months of progressive exercise training improves cardiac magnetic resonance imaging-based measures of cardiac structure and function in well-healed burn survivors. Secondary analyses explored relations between burn surface area and changes in cardiac structure in the cohort of burn survivors.

Hemodynamic Gain Index and Exercise Capacity in Heart Failure With Preserved Ejection Fraction.

Decreased exercise capacity portends a poor prognosis in heart failure with preserved ejection fraction (HFpEF). The hemodynamic gain index (HGI) is an integrated marker of hemodynamic reserve measured during exercise stress testing and is associated with survival. The goal of this study was to establish the association of HGI with exercise capacity, serum biomarkers, and echocardiography features in subjects with HFpEF.

Challenging the Hemodynamic Hypothesis in Heart Failure With Preserved Ejection Fraction: Is Exercise Capacity Limited by Elevated Pulmonary Capillary Wedge Pressure?

Background: Exercise intolerance is a defining characteristic of heart failure with preserved ejection fraction (HFpEF). A marked rise in pulmonary capillary wedge pressure (PCWP) during exertion is pathognomonic for HFpEF and is thought to be a key cause of exercise intolerance. If true, acutely lowering PCWP should improve exercise capacity.