Progressive improvement in hemodynamic response to muscle metaboreflex in heart transplant recipients

Abstract

Exercise capacity remains lower in heart transplant recipients (HTRs) following transplant compared with normal subjects, despite improved cardiac function. Moreover, metaboreceptor activity in the muscle has been reported to increase. The aim of the present investigation was to assess exercise capacity together with metaboreflex activity in HTR patients for 1 yr following heart transplant, to test the hypothesis that recovery in exercise capacity was paralleled by improvements in response to metaboreflex. A cardiopulmonary test for exercise capacity and Vo(2max) and hemodynamic response to metaboreflex activation obtained by postexercise ischemia were gathered in six HTRs and nine healthy controls (CTL) four times: at the beginning of the study (T0, 42 ± 6 days after transplant), at the 3rd, 6th, and 12th month after TO (T1, T2, and T3). The main results were: 1) exercise capacity and Vo(2max) were seen to progressively increase in HTRs; 2) at T0 and T1, HTRs achieved a higher blood pressure response in response to metaboreflex compared with CTL, and this difference disappeared at T2 and T3; and 3) this exaggerated blood pressure response was the result of a systemic vascular resistance increment. This study demonstrates that exercise capacity progressively improves in HTRs after transplant and that this phenomenon is accompanied by a progressive reduction of the metaboreflex-induced increase in blood pressure and systemic vascular resistance. These facts indicate that, despite improved cardiac function, resetting of cardiovascular regulation in HTRs requires months.

Effects of Six Months Training on Physical Capacity and Metaboreflex Activity in Patients with Multiple Sclerosis

“…Moreover, our group has recently demonstrated that MS patients had an altered hemodynamic response to metaboreflex activation (Marongiu et al, 2015). This response resembled that showed by patients with cardiovascular and metabolic disease, where the target blood pressure is reached mainly by means of vasoconstriction (Piepoli et al, 2008; Delaney et al, 2010; Dipla et al, 2010; Choi et al, 2013; Crisafulli et al, 2013; Milia et al, 2015b). In healthy subjects, during the metaboreflex, a cardiac output-mediated mechanism is primarily responsible for the normal increase in mean blood pressure (MBP; Crisafulli et al, 2003, 2008; Delaney et al, 2010; Roberto et al, 2012; Spranger et al, 2013).…”

“…During both the PEMI and the CER test, hemodynamics was assessed by means of impedance cardiography (NCCOM 3, BoMed Inc., Irvine, CA), which has already been used in similar experimental settings (Crisafulli et al, 2007, 2008, 2013; Roberto et al, 2012). The data acquisition method is described in detail in our previous published papers (Crisafulli et al, 2007, 2008, 2013; Roberto et al, 2012).…”

“…The data acquisition method is described in detail in our previous published papers (Crisafulli et al, 2007, 2008, 2013; Roberto et al, 2012). Briefly, by using a digital chart recorder (ADInstruments, PowerLab 8sp, Castle Hill, Australia) NCCOM 3-derived analog traces of ECG, thorax impedance (Z0), and Z0 first derivative were recorded and stored.…”

“…To assess metaboreflex activity, the following procedure was employed: for each parameter, the difference between the PEMI and the CER test was calculated. This procedure allowed us to assess metaboreflex response, i.e., the response due to the metaboreflex activity (Milia et al, 2015a,b; Crisafulli et al, 2013). Differences between groups in mean ± SD of measured variables due to metaboreflex response were assessed by means of two way ANOVA for repeated measures (factors: group and time) followed by Tukey post-hoc when appropriate.…”

Differences in hemodynamic response to metaboreflex activation between obese patients with metabolic syndrome and healthy subjects with obese phenotype

“…Three minutes of recovery were further allowed after the cuff was deflated, for a total of 6 min of recovery. This protocol has been shown to trap the muscle metabolites in the exercising limb and to maintain stimulation of the metaboreceptors (9,15,29,49).…”