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https://www.readbyqxmd.com/read/28329460/model-based-comparison-of-the-normal-and-fontan-circulatory-systems-part-iii
#1
Raymond L Watrous, Alvin J Chin
BACKGROUND: For patients with the Fontan circulatory arrangement, angiotensin-converting enzyme inhibition, guanylate cyclase activation, phosphodiesterase 5 inhibition, and endothelin receptor antagonism have so far resulted in little or no improvement in [Formula: see text] or peak cardiac index (CI), suggesting that our understanding of the factors that most impact the exercise hemodynamics is incomplete. METHODS: To facilitate comparisons with clinical reports of the exercise performance of preadolescent Fontan patients, we rescaled our previously reported computational models of a two-year-old normal child and similarly aged Fontan patient, extended our Fontan model to capture the nonlinear relationship between flow and resistance quantified from previous computational fluid dynamic analyses of the total cavopulmonary connection (TCPC), and added respiration as well as skeletal muscle contraction...
March 2017: World Journal for Pediatric & Congenital Heart Surgery
https://www.readbyqxmd.com/read/28315502/the-effect-of-left-ventricular-assist-device-therapy-in-patients-with-heart-failure-and-mixed-pulmonary-hypertension
#2
Hoong S Lim, Neil Howell, Aaron Ranasinghe
BACKGROUND: Diastolic pressure gradient (DPG) of ≥7 mmHg has been proposed to distinguish mixed pulmonary hypertension from isolated post-capillary pulmonary hypertension in heart failure (HF). We evaluated the changes in pulmonary hemodynamics with left ventricular assist devices (LVADs) in patients with DPG of ≥7 or <7 mmHg, and effects on peak oxygen uptake (VO2) in patients with advanced HF. METHODS: Pre- and post-LVAD implant pulmonary hemodynamics (including right atrial (RA) pressures, DPG, pulmonary vascular resistance (PVR), pulmonary capacitance (PCap) and cardiac output), echocardiography, cardiopulmonary exercise test were measured in 38 consecutive patients...
March 16, 2017: International Journal of Artificial Organs
https://www.readbyqxmd.com/read/28289632/hemodynamic-adaptations-to-regular-exercise-in-people-with-spinal-cord-injury
#3
Young Hee Lee, Jin Hyeong Lee, Sung Hoon Kim, Dongsoo Yi, Kyung Joon Oh, Ji Hyun Kim, Tae Jun Park, Hanul Kim, Jae Seung Chang, In Deok Kong
OBJECTIVE: To investigate the real-time cardiovascular response to the progressive overload exercise in different levels of spinal cord injury (SCI), and to find out whether regular exercise has effect on these cardiovascular responses. METHODS: The study enrolled 8 able-bodied individuals in the control group plus 15 SCI subjects who were divided into two groups by their neurological level of injury: high-level SCI group (T6 or above) and low-level SCI group (T7 or below)...
February 2017: Annals of Rehabilitation Medicine
https://www.readbyqxmd.com/read/28277406/comparable-neutrophil-responses-for-arm-and-intensity-matched-leg-exercise
#4
Christof A Leicht, Victoria L Goosey-Tolfrey, Nicolette C Bishop
INTRODUCTION: Arm exercise is performed at lower absolute intensities than lower body exercise. This may impact on intensity dependent neutrophil responses and it is unknown whether individuals restricted to arm exercise experience the same changes in the neutrophil response as found for lower body exercise. Therefore, we aimed to investigate the importance of exercise modality and relative exercise intensity on the neutrophil response. METHODS: Twelve moderately trained males performed three 45-min constant load exercise trials following determination of peak oxygen uptake for arm exercise (V[Combining Dot Above]O2peak arms) and cycling (V[Combining Dot Above]O2peak legs): (1) arm cranking exercise at 60%V[Combining Dot Above]O2peak arms; (2) moderate cycling at 60%V[Combining Dot Above]O2peak legs; and (3) easy cycling at 60%V[Combining Dot Above]O2peak arms...
March 8, 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28256427/midterm-effect-of-balloon-pulmonary-angioplasty-on-hemodynamics-and-subclinical-myocardial-damage-in-chronic-thromboembolic-pulmonary-hypertension
#5
Mai Kimura, Takashi Kohno, Takashi Kawakami, Masaharu Kataoka, Toshimitsu Tsugu, Keitaro Akita, Sarasa Isobe, Yuji Itabashi, Yuichiro Maekawa, Mitsushige Murata, Keiichi Fukuda
BACKGROUND: The acute favourable effect of balloon pulmonary angioplasty (BPA) has been proven in patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, data on its effect 6 months after therapy (from now on referred to as mid-term) and influence on the right ventricle and myocardial damage are sparse. To evaluate factors that influence improvement in cardiac output (CO) and subclinical myocardial damage, we examined hemodynamics and serum high-sensitivity troponin T (hs-TnT) levels before, 1 week after, and 6 months after BPA...
December 8, 2016: Canadian Journal of Cardiology
https://www.readbyqxmd.com/read/28255866/heart-failure-with-preserved-ejection-fraction-and-skeletal-muscle-physiology
#6
REVIEW
Stephen D Farris, Farid Moussavi-Harami, April Stempien-Otero
Heart failure with preserved ejection fraction (HFpEF) accounts for half of all heart failure in the USA, increases in prevalence with aging, and has no effective therapies. Intriguingly, the pathophysiology of HFpEF has many commonalities with the aged cardiovascular system including reductions in diastolic compliance, chronotropic defects, increased resistance in the peripheral vasculature, and poor energy substrate utilization. Decreased exercise capacity is a cardinal symptom of HFpEF. However, its severity is often out of proportion to changes in cardiac output...
March 2017: Heart Failure Reviews
https://www.readbyqxmd.com/read/28255448/effects-of-different-early-rehabilitation-techniques-on-haemodynamic-and-metabolic-parameters-in-sedated-patients-protocol-for-a-randomised-single-bind-cross-over-trial
#7
Clément Medrinal, Yann Combret, Guillaume Prieur, Aurora Robledo Quesada, Tristan Bonnevie, Francis Edouard Gravier, Éric Frenoy, Olivier Contal, Bouchra Lamia
INTRODUCTION: Early rehabilitation has become widespread practice for patients in intensive care; however, the prevalence of intensive care unit-acquired weakness remains high and the majority of physiotherapy is carried out in bed. Several inbed rehabilitation methods exist, but we hypothesise that techniques that provoke muscle contractions are more effective than passive techniques. METHODS: A randomised, controlled cross-over study will be carried out to evaluate and compare the effectiveness of early rehabilitation techniques on cardiac output (CO) in sedated patients in intensive care...
2017: BMJ Open Respiratory Research
https://www.readbyqxmd.com/read/28255088/oral-n-acetylcysteine-and-exercise-tolerance-in-mild-chronic-obstructive-pulmonary-disease
#8
Daniel M Hirai, Joshua H Jones, Joel T Zelt, Marianne L da Silva, Robert F Bentley, Brittany Ann Edgett, Brendon James Gurd, Michael E Tschakovsky, Denis E O'Donnell, J Alberto Neder
Heightened oxidative stress is implicated in the progressive impairment of skeletal muscle vascular and mitochondrial function in chronic obstructive pulmonary disease (COPD). Whether accumulation of reactive oxygen species contribute to exercise intolerance in the early stages of COPD is unknown. We examined the effects of oral antioxidant treatment with N-acetylcysteine (NAC) on respiratory, cardiovascular and locomotor muscle function and exercise tolerance in patients with mild COPD. Thirteen patients with forced expiratory volume in one second and forced vital capacity ratio (FEV1/FVC) < lower limit of normal (LLN) and FEV1 ≥ LLN were enrolled in a double-blind, randomized crossover study to receive NAC (1800 mg/day) or placebo for 4 days...
March 2, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28240953/cardiorespiratory-function-in-thoroughbreds-during-locomotion-on-a-treadmill-at-an-incline-or-decline
#9
Hajime Ohmura, Kazutaka Mukai, Toshiyuki Takahashi, Hiroko Aida, James H Jones
OBJECTIVE To determine cardiorespiratory responses of Thoroughbreds to uphill and downhill locomotion on a treadmill at identical gradients. ANIMALS 5 highly trained Thoroughbred geldings. PROCEDURES Thoroughbreds were exercised for 2-minute intervals on a treadmill at 1.7, 3.5, 6.0, 8.0, and 10.0 m/s at a 4% incline, 0% incline (horizontal plane), and 4% decline in random order on different days. Stride frequency, stride length, and cardiopulmonary and O2-transport variables were measured and analyzed by means of repeated-measures ANOVA and Holm-Šidák pairwise comparisons...
March 2017: American Journal of Veterinary Research
https://www.readbyqxmd.com/read/28240427/mitral-systolic-velocity-at-peak-exercise-predicts-impaired-exercise-capacity-in-patients-with-heart-failure-with-preserved-ejection-fraction
#10
Kenji Masada, Takayuki Hidaka, Yu Harada, Mirai Kinoshita, Kiho Itakura, Akifumi Higashi, Hiroto Utsunomiya, Yasuki Kihara
BACKGROUND: Nearly half of patients with heart failure have normal left ventricular ejection fraction (LVEF), but their prognosis is no better than those with reduced LVEF. Although peak oxygen consumption (VO2 ) is an independent predictor of mortality in heart failure, it is unclear how cardiac function during exercise contributes to peak VO2 . Therefore, we explored the useful parameters measured by exercise stress echocardiography to predict peak VO2 in patients with heart failure with preserved LVEF (HFpEF)...
February 2017: Echocardiography
https://www.readbyqxmd.com/read/28240387/linear-and-nonlinear-contributions-to-oxygen-transport-and-utilization-during-moderate-random-exercise-in-humans
#11
T Beltrame, R L Hughson
The assumption of the aerobic system linearity implies that the pulmonary oxygen uptake (pV̇O2) dynamic during exercise transitions present a first-order characteristic. The main objective of this study was to test the linearity of the oxygen delivery-utilization balance during random moderate exercise. The cardiac output (Q̇) and deoxygenated hemoglobin (HHb) were measured to infer about the central and local O2 availability, respectively. Thirteen healthy men performed two consecutive pseudorandom binary sequence cycling exercises followed by an incremental protocol...
February 27, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28239994/aortic-stenosis-in-dialysis-patients
#12
REVIEW
Yousif Ahmad, Michael F Bellamy, Christopher S R Baker
Aortic valve stenosis occurs 10-20 years earlier in patients on dialysis compared with the general population. This is likely related to the exposure of the valve to a milieu that predisposes to calcification as well as increased shear stress across the valve. Objective assessment of stenosis severity is largely made using echocardiography though accurate interpretation requires an understanding of the potential pitfalls of the technique and the influence of cardiac output upon the gradient measured across the valve...
February 26, 2017: Seminars in Dialysis
https://www.readbyqxmd.com/read/28238048/dynamics-of-the-rr-interval-versus-blood-pressure-relationship-at-exercise-onset-in-humans
#13
Aurélien Bringard, Alessandra Adami, Nazzareno Fagoni, Timothée Fontolliet, Frédéric Lador, Christian Moia, Enrico Tam, Guido Ferretti
PURPOSE: The dynamics of the postulated phenomenon of exercise baroreflex resetting is poorly understood, but can be investigated using closed-loop procedures. To shed light on some mechanisms and temporal relationships participating in the resetting process, we studied the time course of the relationship between the R-R interval (RRi) and arterial pressure with a closed-loop approach. METHODS: On ten young volunteers at rest and during light exercise in supine and upright position, we continuously determined, on single-beat basis, RRi (electrocardiography), and arterial pressure (non-invasive finger pressure cuff)...
February 25, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28236850/intermittent-hypoxia-as-a-means-to-improve-aerobic-capacity-in-type-2-diabetes
#14
R J Leone, S Lalande
Physical inactivity and a low maximal aerobic capacity (VO2max) strongly predict morbidity and mortality in patients with type 2 diabetes (T2D). Patients with T2D have a reduced VO2max when compared with healthy individuals of similar age, weight, and physical activity levels, and this lower aerobic capacity is usually attributed to a reduced oxygen delivery to the working muscles. The oxygen carrying capacity of the blood, as well as increases in cardiac output and blood flow, contribute to the delivery of oxygen to the active muscles during exercise...
March 2017: Medical Hypotheses
https://www.readbyqxmd.com/read/28236163/comparison-of-patients-undergoing-surgical-versus-transcatheter-pulmonary-valve-replacement-criteria-for-referral-and-mid-term-outcome
#15
Jenny E Zablah, Nilanjana Misra, Dorota Gruber, Dipak Kholwadwala, Shilpi Epstein
Pulmonary regurgitation and/or stenosis (PS) is challenging in patients with congenital heart defects. Our aim was to identify if criteria for referral were different between surgical (SPVR) and transcatheter pulmonary valve replacement (TPVR) populations, and to further assess if any baseline differences influence the resultant ventricular remodeling at medium-term follow-up. Retrospective chart review of patients post-SPVR or TPVR at our center from 2013 to 2015 was conducted. Volumetric data from cardiac magnetic resonance (CMR), 1 year before and 1 year after PVR was obtained...
March 2017: Pediatric Cardiology
https://www.readbyqxmd.com/read/28219104/captopril-does-not-potentiate-post-exercise-hypotension-a-randomized-crossover-study
#16
Andréia Cristiane Carrenho Queiroz, Julio Cesar Silva Sousa, Natan Daniel Silva, Eleonora Tobaldini, Katia Coelho Ortega, Edilamar Menezes de Oliveira, Patricia Chakur Brum, Nicola Montano, Decio Mion, Taís Tinucci, Claudia Lucia de Moraes Forjaz
To evaluate whether captopril (3×50 mg/day) potentiates post-resistance exercise hypotension (PREH) in hypertensives (HT), 12 HT men received captopril and placebo for 4 weeks each in a double-blinded, randomized-crossover design. On each therapy, subjects underwent 2 sessions: Control (C - rest) and Resistance Exercise (RE - 7 exercises, 3 sets to moderate fatigue, 50% of 1 RM -repetition maximum). Measurements were taken before and after 30-60 min (Post1) and 7 h (Post2), and ambulatory blood pressure (BP) was monitored for 24 h...
February 20, 2017: International Journal of Sports Medicine
https://www.readbyqxmd.com/read/28215595/gas-exchange-kinetics-following-concentric-eccentric-isokinetic-arm-and-leg-exercise
#17
U Drescher, S Mookerjee, A Steegmanns, A Knicker, U Hoffmann
PURPOSE: To evaluate the effects of exercise velocity (60, 150, 240deg∙s(-1)) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO2) following high-intensity concentric-eccentric isokinetic exercise. METHODS: Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t1/2) for oxygen uptake (V˙O2pulm), carbon dioxide output (V˙CO2pulm), and ventilation (V˙E)...
February 17, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28212401/preload-based-starling-like-control-of-rotary-blood-pumps-an-in-vitro-evaluation
#18
Mahdi Mansouri, Shaun D Gregory, Robert F Salamonsen, Nigel H Lovell, Michael C Stevens, Jo P Pauls, Rini Akmeliawati, Einly Lim
Due to a shortage of donor hearts, rotary left ventricular assist devices (LVADs) are used to provide mechanical circulatory support. To address the preload insensitivity of the constant speed controller (CSC) used in conventional LVADs, we developed a preload-based Starling-like controller (SLC). The SLC emulates the Starling law of the heart to maintain mean pump flow ([Formula: see text]) with respect to mean left ventricular end diastolic pressure (PLVEDm) as the feedback signal. The SLC and CSC were compared using a mock circulation loop to assess their capacity to increase cardiac output during mild exercise while avoiding ventricular suction (marked by a negative PLVEDm) and maintaining circulatory stability during blood loss and severe reductions in left ventricular contractility (LVC)...
2017: PloS One
https://www.readbyqxmd.com/read/28187374/the-strengths-and-weaknesses-of-non-invasive-parameters-obtained-by-echocardiography-and-cardiopulmonary-exercise-testing-in-comparison-with-the-hemodynamic-assessment-by-the-right-heart-catheterization-in-patients-with-pulmonary-hypertension
#19
Katarzyna Ptaszyńska-Kopczyńska, Anna Krentowska, Emilia Sawicka, Anna Skoneczny, Małgorzata Jasiewicz, Małgorzata Knapp, Włodzimierz J Musiał, Bożena Sobkowicz, Karol A Kamiński
PURPOSE: Pulmonary hypertension (PH) diagnosis requires invasive assessment by right heart catheterization (RHC), but screening and monitoring are performed using non-invasive methods: echocardiography and cardiopulmonary exercise testing (CPET). The aim of the study was to assess correlations between the parameters obtained in non-invasive testing and RHC in patients with PH of different etiologies. MATERIAL/METHODS: The study included 53 medical records of PH patients (32 women) aged 29-81 years...
June 14, 2016: Advances in Medical Sciences
https://www.readbyqxmd.com/read/28186430/cerebral-blood-flow-frontal-lobe-oxygenation-and-intra-arterial-blood-pressure-during-sprint-exercise-in-normoxia-and-severe-acute-hypoxia-in-humans
#20
David Curtelin, David Morales-Alamo, Rafael Torres-Peralta, Peter Rasmussen, Marcos Martin-Rincon, Mario Perez-Valera, Christoph Siebenmann, Ismael Pérez-Suárez, Evgenia Cherouveim, A William Sheel, Carsten Lundby, José Al Calbet
Cerebral blood flow (CBF) is regulated to secure brain O2 delivery while simultaneously avoiding hyperperfusion; however, both requisites may conflict during sprint exercise. To determine whether brain O2 delivery or CBF is prioritized, young men performed sprint exercise in normoxia and hypoxia (PIO2 = 73 mmHg). During the sprints, cardiac output increased to ∼22 L min(-1), mean arterial pressure to ∼131 mmHg and peak systolic blood pressure ranged between 200 and 304 mmHg. Middle-cerebral artery velocity (MCAv) increased to peak values (∼16%) after 7...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
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