Attenuated Microcirculatory Response to Maximal Exercise in Patients With Chronic Heart Failure

Exercise training in heart transplantation

Heart transplantation remains the gold standard in the treatment of end-stage heart failure (HF). Heart transplantation patients present lower exercise capacity due to cardiovascular and musculoskeletal alterations leading thus to poor quality of life and reduction in the ability of daily self-service. Impaired vascular function and diastolic dysfunction cause lower cardiac output while decreased skeletal muscle oxidative fibers, enzymes and capillarity cause arteriovenous oxygen difference, leading thus to decreased peak oxygen uptake in heart transplant recipients. Exercise training improves exercise capacity, cardiac and vascular endothelial function in heart transplant recipients. Pre-rehabilitation regular aerobic or combined exercise is beneficial for patients with end-stage HF awaiting heart transplantation in order to maintain a higher fitness level and reduce complications afterwards like intensive care unit acquired weakness or cardiac cachexia. All hospitalized patients after heart transplantation should be referred to early mobilization of skeletal muscles through kinesiotherapy of the upper and lower limbs and respiratory physiotherapy in order to prevent infections of the respiratory system prior to hospital discharge. Moreover, all heart transplant recipients after hospital discharge who have not already participated in an early cardiac rehabilitation program should be referred to a rehabilitation center by their health care provider. Although high intensity interval training seems to have more benefits than moderate intensity continuous training, especially in stable transplant patients, individualized training based on the abilities and needs of each patient still remains the most appropriate approach. Cardiac rehabilitation appears to be safe in heart transplant patients. However, long-term follow-up data is incomplete and, therefore, further high quality and adequately-powered studies are needed to demonstrate the long-term benefits of exercise training in this population.

Heart Failure-Induced Skeletal Muscle Wasting

PURPOSE OF REVIEW

Heart failure (HF) is a structural or functional cardiac abnormality which leads to failure of the heart to deliver oxygen commensurately with the requirements of the tissues and it may progress to a generalized wasting of skeletal muscle, fat tissue, and bone tissue (cardiac cachexia). Clinically, dyspnea, fatigue, and exercise intolerance are some typical signs and symptoms that characterize HF patients. This review focused on the phenotypic characteristics of HF-induced skeletal myopathy as well as the mechanisms of muscle wasting due to HF and highlighted possible therapeutic strategies for skeletal muscle wasting in HF.

RECENT FINDINGS

The impaired exercise capacity of those patients is not attributed to the reduced blood flow in the exercising muscles, but rather to abnormal metabolic responses, myocyte apoptosis and atrophy of skeletal muscle. Specifically, the development of skeletal muscle wasting in chronic HF is characterized by structural, metabolic, and functional abnormalities in skeletal muscle and may be a result not only of reduced physical activity, but also of metabolic or hormonal derangements that favour catabolism over anabolism. In particular, abnormal energy metabolism, mitochondrial dysfunction, transition of myofibers from type I to type II, muscle atrophy, and reduction in muscular strength are included in skeletal muscle abnormalities which play a central role in the decreased exercise capacity of HF patients. Skeletal muscle alterations and exercise intolerance observed in HF are reversible by exercise training, since it is the only demonstrated intervention able to improve skeletal muscle metabolism, growth factor activity, and functional capacity and to reverse peripheral abnormalities.

The acute and long-term effects of a cardiac rehabilitation program on endothelial progenitor cells in chronic heart failure patients: Comparing two different exercise training protocols

Background

Vascular endothelial dysfunction is an underlying pathophysiological feature of chronic heart failure (CHF). Endothelial progenitor cells (EPCs) are also impaired. The purpose of the study was to assess the effect of a cardiac rehabilitation (CR) program on the increase of EPCs at rest and on the acute response after maximal exercise in patients with CHF and investigate whether there were differences between two exercise training protocols and patients of NYHA II and III classes.

Methods

Forty-four patients with stable CHF enrolled in a 36-session CR program and were randomized in one training protocol; either high-intensity interval training (HIIT) or HIIT combined with muscle strength (COM). All patients underwent maximum cardiopulmonary exercise testing (CPET) before and after the CR program and venous blood was drawn before and after each CPET. Five endothelial cellular populations, expressed as cells/10⁶ enucleated cells, were quantified by flow cytometry.

Results

An increase in all endothelial cellular populations at rest was observed after the CR program (p < 0.01). The acute response after maximum exercise increased in 4 out of 5 endothelial cellular populations after rehabilitation. Although there was increase in EPCs at rest and the acute response after rehabilitation in each exercise training group and each NYHA class, there were no differences between HIIT and COM groups or NYHA II and NYHA III classes (p > 0.05).

Conclusions

A 36-session CR program increases the acute response after maximum CPET and stimulates the long-term mobilization of EPCs at rest in patients with CHF. These benefits seem to be similar between HIIT and COM exercise training protocols and between patients of different functional classes.

Endothelial progenitor cells mobilization after maximal exercise according to heart failure severity

BACKGROUND

Vascular endothelial dysfunction is an underlying pathophysiological feature of chronic heart failure (CHF). Patients with CHF are characterized by impaired vasodilation and inflammation of the vascular endothelium. They also have low levels of endothelial progenitor cells (EPCs). EPCs are bone marrow derived cells involved in endothelium regeneration, homeostasis, and neovascularization. Exercise has been shown to improve vasodilation and stimulate the mobilization of EPCs in healthy people and patients with cardiovascular comorbidities. However, the effects of exercise on EPCs in different stages of CHF remain under investigation.

AIM

To evaluate the effect of a symptom-limited maximal cardiopulmonary exercise testing (CPET) on EPCs in CHF patients of different severity.

METHODS

Forty-nine consecutive patients (41 males) with stable CHF [mean age (years): 56 ± 10, ejection fraction (EF, %): 32 ± 8, peak oxygen uptake (VO₂, mL/kg/min): 18.1 ± 4.4] underwent a CPET on a cycle ergometer. Venous blood was sampled before and after CPET. Five circulating endothelial populations were quantified by flow cytometry: Three subgroups of EPCs [CD34⁺/CD45^-/CD133⁺, CD34⁺/CD45^-/CD133⁺/VEGFR₂ and CD34⁺/CD133⁺/vascular endothelial growth factor receptor 2 (VEGFR₂)] and two subgroups of circulating endothelial cells (CD34⁺/CD45^-/CD133^- and CD34⁺/CD45^-/CD133^-/VEGFR₂). Patients were divided in two groups of severity according to the median value of peak VO₂ (18.0 mL/kg/min), predicted peak VO₂ (65.5%), ventilation/carbon dioxide output slope (32.5) and EF (reduced and mid-ranged EF). EPCs values are expressed as median (25th-75th percentiles) in cells/10⁶ enucleated cells.

RESULTS

Patients with lower peak VO₂ increased the mobilization of CD34⁺/CD45^-/CD133⁺ [pre CPET: 60 (25-76) vs post CPET: 90 (70-103) cells/10⁶ enucleated cells, P < 0.001], CD34⁺/CD45^-/CD133⁺/VEGFR₂ [pre CPET: 1 (1-4) vs post CPET: 5 (3-8) cells/10⁶ enucleated cells, P < 0.001], CD34⁺/CD45^-/CD133^- [pre CPET: 186 (141-361) vs post CPET: 488 (247-658) cells/10⁶ enucleated cells, P < 0.001] and CD34⁺/CD45^-/CD133^-/VEGFR₂ [pre CPET: 2 (1-2) vs post CPET: 3 (2-5) cells/10⁶ enucleated cells, P < 0.001], while patients with higher VO₂ increased the mobilization of CD34⁺/CD45^-/CD133⁺ [pre CPET: 42 (19-73) vs post CPET: 90 (39-118) cells/10⁶ enucleated cells, P < 0.001], CD34⁺/CD45^-/CD133⁺/VEGFR₂ [pre CPET: 2 (1-3) vs post CPET: 6 (3-9) cells/10⁶ enucleated cells, P < 0.001], CD34⁺/CD133⁺/VEGFR₂ [pre CPET: 10 (7-18) vs post CPET: 14 (10-19) cells/10⁶ enucleated cells, P < 0.01], CD34⁺/CD45^-/CD133^- [pre CPET: 218 (158-247) vs post CPET: 311 (254-569) cells/10⁶ enucleated cells, P < 0.001] and CD34⁺/CD45^-/CD133^-/VEGFR₂ [pre CPET: 1 (1-2) vs post CPET: 4 (2-6) cells/10⁶ enucleated cells, P < 0.001]. A similar increase in the mobilization of at least four out of five cellular populations was observed after maximal exercise within each severity group regarding predicted peak, ventilation/carbon dioxide output slope and EF as well (P < 0.05). However, there were no statistically significant differences in the mobilization of endothelial cellular populations between severity groups in each comparison (P > 0.05).

CONCLUSION

Our study has shown an increased EPCs and circulating endothelial cells mobilization after maximal exercise in CHF patients, but this increase was not associated with syndrome severity. Further investigation, however, is needed.

Photobiomodulation therapy combined with carvedilol attenuates post-infarction heart failure by suppressing excessive inflammation and oxidative stress in rats

The post-myocardial infarction heart failure (HF) still carries a huge burden since current therapy is unsuccessful to abrogate poor prognosis. Thus, new approaches are needed, and photobiomodulation therapy (PBMt) may be a way. However, it is not known whether PBMt added to a standard HF therapy provides additional improvement in cardiac remodeling in infarcted rats. This study sought to determine the combined carvedilol-drug and PBMt with low-level laser therapy value in HF. Rats with large infarcts were treated for 30 days. The functional fitness was evaluated using a motorized treadmill. Echocardiography and hemodynamic measurements were used for functional evaluations of left ventricular (LV). ELISA, Western blot and biochemical assays were used to evaluate inflammation and oxidative stress in the myocardium. Carvedilol and PBMt had a similar action in normalizing pulmonary congestion and LV end-diastolic pressure, attenuating LV dilation, and improving LV systolic function. Moreover, the application of PBMt to carvedilol-treated rats inhibited myocardial hypertrophy and improved +dP/dt of LV. PBMt alone prevented inflammation with a superior effect than carvedilol. Carvedilol and PBMt normalized 4-hydroxynonenal (a lipoperoxidation marker) levels in the myocardium. However, importantly, the addition of PBMt to carvedilol attenuated oxidized protein content and triggered a high activity of the anti-oxidant catalase enzyme. In conclusion, these data show that the use of PBMt plus carvedilol therapy results in a significant additional improvement in HF in a rat model of myocardial infarction. These beneficial effects were observed to be due, at least in part, to decreased myocardial inflammation and oxidative stress.

Muscle microcirculation alterations and relation to dipping status in newly diagnosed untreated patients with arterial hypertension-A pilot study

OBJECTIVE

The importance of abnormalities observed in the microcirculation of patients with arterial hypertension (AH) is being increasingly recognized. The authors aimed to evaluate skeletal muscle microcirculation in untreated, newly diagnosed hypertensive patients with NIRS, a noninvasive method that evaluates microcirculation.

METHODS

We evaluated 34 subjects, 17 patients with AH (13 males, 49±13 years, BMI: 26±2 kg/m² ) and 17 healthy controls (12 males, 49±15 years, BMI: 25±3 kg/m² ). The thenar muscle StO₂ (%) was measured by NIRS before, during and after 3-minutes vascular occlusion to calculate OCR (%/min), EF (%/min), and RHT (minute). The dipping status of hypertensive patients was assessed.

RESULTS

The RHT differed between AH patients and healthy subjects (2.6±0.3 vs 2.1±0.3 minutes, P<.001). Dippers had higher EF than nondippers (939±280 vs 710±164%/min, P=.05).

CONCLUSIONS

The study suggests an impaired muscle microcirculation in newly diagnosed, untreated AH patients.