Purpose The exercise pressor reflex (EPR) plays a fundamental role in physiological reactions to exercise in humans and in the pathophysiology of cardiovascular disorders. There is no "gold standard" method for EPR assessment; therefore, we propose a new protocol for testing interactions between the muscle mechanoreflex and metaboreflex (major components of EPR). Methods Thirty-four healthy subjects (mean age [± standard deviation] 24 ± 4 years, 22 men) were enrolled in the study. During the study, the hemodynamic and ventilatory parameters of these subjects were continuously monitored using our proposed assessment method. This assessment method consists of an initial 5-min rest period (baseline) followed by 5 min of passive cycling (PC) on an automated cycle ergometer (mechanoreceptor stimulation), after which tourniquet cuffs located bilaterally on the upper thighs are inflated for 3 min to evoke venous and arterial regional circulatory occlusion (CO) during PC (metaboreceptor stimulation). Deflation of the tourniquet cuffs is followed by a second 5 min of PC and finally by a 5-min recovery time. The control test comprises a 5-min rest period, followed by 3 min of CO only and a final 5-min recovery. Results Mean arterial pressure (MAP) and minute ventilation (MV) increased significantly during PC (MAP: from 90 ± 9.3 to 95 ± 9.7 mmHg; MV: from 11.5 ± 2.5 to 13.5 ± 2.9 L/min; both p < 0.05) and again when CO was applied (MAP: from 95 ± 9.7 to 101 ± 11.0 mmHg; MV: from 13.5 ± 2.9 to 14.8 ± 3.8 L/min; both p < 0.05). In the control test there was a slight increase in MAP during CO (from 92 ± 10.5 to 94 ± 10.0 mmHg; p < 0.05) and no changes in the ventilatory parameters. Conclusion Bilateral leg passive cycling with concomitant circulatory occlusion is a new, simple and effective method for testing interactions between the mechanoreflex and metaboreflex in humans.
A b s t r a c tBackground: Acute heart failure (AHF), occurring as a complication of ongoing acute myocardial infarction (AMI), is a common predictor of worse clinical outcome. Much less is known about the unique subpopulation of patients who present these two life-threatening conditions in the emergency department (ED). Aim:The aim of the study was to establish the prevalence of coexistence of AHF with AMI in the ED, to identify clinical factors associated with the higher prevalence of AHF at very early onset of AMI, and to assess the prognostic impact of the presence of AHF with AMI. Methods:A prospective study of 289 consecutive patients (mean age: 68 ± 11 years, 61% men) admitted to our institution (via the ED) with the diagnosis of AMI between May and October 2012 and followed-up for 2.5 years.Results: Acute heart failure was diagnosed in 13% of patients in the ED. In multivariable analysis, female sex, chronic obstructive pulmonary disease, and chronic kidney disease significantly increased the risk of developing AHF together with AMI (all p < 0.05). Patients with AHF were hospitalised for longer (9.2 ± 6.1 vs. 6.3 ± 4.5 days, p < 0.001), had higher in-hospital cardiovascular mortality (8% vs. 0%, p < 0.001), and all-cause (34% vs. 15%, p = 0.004) and cardiovascular mortality (26% vs. 9%, p = 0.002) during long-term follow-up. Conclusions:Despite good logistic-and evidence-based treatment, AHF is present in one in eight patients with AMI at the time of admission to the ED. Particularly poor outcomes characterise critically ill patients; therefore, great effort should be undertaken to improve their care.
The exercise pressor reflex (EPR) plays an essential role in cardiovascular and ventilatory responses to physical activity. Despite immense meaning and increasing validation of the EPR, there is no agreement on the character of interactions between its components and other reflexes in health and disease. The data addressing this issue remain incomplete and incoherent, partially due to various challenges in testing these pathways. The mounting evidence of EPR malfunction contribution to sympathetic over-activation in heart failure and other cardiovascular diseases shows clinical importance of comprehensive understanding of these mechanisms. In this review, we briefly summarize experiments focused on the issue of interactions between mechano-, metabo, chemo-, and baroreflex during exercise. We also address potential reasons of discrepancies in the results, identify gaps in this particular scientific area and propose notional pathways for future research. This article highlights the clinical importance of the EPR deterioration in heart failure pathophysiology and discusses potential therapies focused on restoring the reflex pathways. In addition, consideration is given to the latest sophisticated experiments in this area, underlining the need of changing the paradigm in EPR interactions studying – from teleological to mechanistic approach.
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