Non-invasive detection of coronary endothelial response to sequential handgrip exercise in coronary artery disease patients and healthy adults.

OBJECTIVES: Our objective is to test the hypothesis that coronary endothelial function (CorEndoFx) does not change with repeated isometric handgrip (IHG) stress in CAD patients or healthy subjects. BACKGROUND: Coronary responses to endothelial-dependent stressors are important measures of vascular risk that can change in response to environmental stimuli or pharmacologic interventions. The evaluation of the effect of an acute intervention on endothelial response is only valid if the measurement does not change significantly in the short term under normal conditions. Using 3.0 Tesla (T) MRI, we non-invasively compared two coronary artery endothelial function measurements separated by a ten minute interval in healthy subjects and patients with coronary artery disease (CAD). METHODS: Twenty healthy adult subjects and 12 CAD patients were studied on a commercial 3.0 T whole-body MR imaging system. Coronary cross-sectional area (CSA), peak diastolic coronary flow velocity (PDFV) and blood-flow were quantified before and during continuous IHG stress, an endothelial-dependent stressor. The IHG exercise with imaging was repeated after a 10 minute recovery period. RESULTS: In healthy adults, coronary artery CSA changes and blood-flow increases did not differ between the first and second stresses (mean % change ±SEM, first vs. second stress CSA: 14.8%±3.3% vs. 17.8%±3.6%, p = 0.24; PDFV: 27.5%±4.9% vs. 24.2%±4.5%, p = 0.54; blood-flow: 44.3%±8.3 vs. 44.8%±8.1, p = 0.84). The coronary vasoreactive responses in the CAD patients also did not differ between the first and second stresses (mean % change ±SEM, first stress vs. second stress: CSA: -6.4%±2.0% vs. -5.0%±2.4%, p = 0.22; PDFV: -4.0%±4.6% vs. -4.2%±5.3%, p = 0.83; blood-flow: -9.7%±5.1% vs. -8.7%±6.3%, p = 0.38). CONCLUSION: MRI measures of CorEndoFx are unchanged during repeated isometric handgrip exercise tests in CAD patients and healthy adults. These findings demonstrate the repeatability of noninvasive 3T MRI assessment of CorEndoFx and support its use in future studies designed to determine the effects of acute interventions on coronary vasoreactivity.

Coronary vasomotor responses to isometric handgrip exercise are primarily mediated by nitric oxide: a noninvasive MRI test of coronary endothelial function.

Endothelial cell release of nitric oxide (NO) is a defining characteristic of nondiseased arteries, and abnormal endothelial NO release is both a marker of early atherosclerosis and a predictor of its progression and future events. Healthy coronaries respond to endothelial-dependent stressors with vasodilatation and increased coronary blood flow (CBF), but those with endothelial dysfunction respond with paradoxical vasoconstriction and reduced CBF. Recently, coronary MRI and isometric handgrip exercise (IHE) were reported to noninvasively quantify coronary endothelial function (CEF). However, it is not known whether the coronary response to IHE is actually mediated by NO and/or whether it is reproducible over weeks. To determine the contribution of NO, we studied the coronary response to IHE before and during infusion of N(G)-monomethyl-l-arginine (l-NMMA, 0.3 mg·kg(-1)·min(-1)), a NO-synthase inhibitor, in healthy volunteers. For reproducibility, we performed two MRI-IHE studies ∼8 wk apart in healthy subjects and patients with coronary artery disease (CAD). Changes from rest to IHE in coronary cross-sectional area (%CSA) and diastolic CBF (%CBF) were quantified. l-NMMA completely blocked normal coronary vasodilation during IHE [%CSA, 12.9 ± 2.5 (mean ± SE, placebo) vs. -0.3 ± 1.6% (l-NMMA); P < 0.001] and significantly blunted the increase in flow [%CBF, 47.7 ± 6.4 (placebo) vs. 10.6 ± 4.6% (l-NMMA); P < 0.001]. MRI-IHE measures obtained weeks apart strongly correlated for CSA (P < 0.0001) and CBF (P < 0.01). In conclusion, the normal human coronary vasoactive response to IHE is primarily mediated by NO. This noninvasive, reproducible MRI-IHE exam of NO-mediated CEF promises to be useful for studying CAD pathogenesis in low-risk populations and for evaluating translational strategies designed to alter CAD in patients.

Bilateral symmetry of radial pulse in high-level tennis players: implications for the validity of central aortic pulse wave analysis.

BACKGROUND: Reconstruction of the central aortic pressure wave from the noninvasive recording of the radial pulse with applanation tonometry has become a standard tool in the field of hypertension. It is not presently known whether recording the radial pulse on the dominant or the nondominant side has any effect on such reconstruction. METHOD: We carried out radial applanation tonometry on both forearms in young, healthy, male volunteers, who were either sedentary (n = 11) or high-level tennis players (n = 10). The purpose of including tennis players was to investigate individuals with extreme asymmetry between the dominant and nondominant upper limb. RESULTS: In the sedentary individuals, forearm circumference and handgrip strength were slightly larger on the dominant (mean +/- SD respectively 27.9 +/- 1.5 cm and 53.8 +/- 10 kg) than on nondominant side (27.3 +/- 1.6 cm, P < 0.001 vs. dominant, and 52.1 +/- 11 kg, P = NS). In the tennis players, differences between sides were more conspicuous (forearm circumference: dominant 28.0 +/- 1.7 cm nondominant 26.4 +/- 1.5 cm, P < 0.001; handgrip strength 61.4 +/- 10.8 vs. 53.4 +/- 9.7 kg, P < 0.001). We found that in both sedentary individuals and tennis players, the radial pulse had identical shape on both sides and, consequently, the reconstructed central aortic pressure waveforms, as well as derived indices of central pulsatility, were not dependent on the side where applanation tonometry was carried out. CONCLUSION: Evidence from individuals with maximal asymmetry of dominant vs. nondominant upper limb indicates that laterality of measurement is not a methodological issue for central pulse wave analysis carried out with radial applanation tonometry.

Fitness, sport et pression artérielle [Fitness, sports and blood pressure].

Blood pressure is lowered for a few hours after aerobic exercise, but also after resistance exercise, although for a shorter period of time. An exercise program can significantly lower resting and ambulatory BP measurements. Multiple mechanisms interact for the BP lowering effect, such as decreased total peripheral resistance, enhanced endothelial function, diminished sympathetic or rennin plasmatic activity, structural vascular modifications and baroreceptor reflex modulation. New exercises like eccentric or isometric (handgrip) contractions are promising. Resistance activities have long been considered dangerous for blood vessels because of increased arterial stiffness, but if the intensity remains moderate and aerobic exercises are integrated, then the effects are altogether beneficial.

Non-invasive and non-occlusive blood pressure estimation via a chest sensor.

The clinical demand for a device to monitor Blood Pressure (BP) in ambulatory scenarios with minimal use of inflation cuffs is increasing. Based on the so-called Pulse Wave Velocity (PWV) principle, this paper introduces and evaluates a novel concept of BP monitor that can be fully integrated within a chest sensor. After a preliminary calibration, the sensor provides non-occlusive beat-by-beat estimations of Mean Arterial Pressure (MAP) by measuring the Pulse Transit Time (PTT) of arterial pressure pulses travelling from the ascending aorta towards the subcutaneous vasculature of the chest. In a cohort of 15 healthy male subjects, a total of 462 simultaneous readings consisting of reference MAP and chest PTT were acquired. Each subject was recorded at three different days: D, D+3 and D+14. Overall, the implemented protocol induced MAP values to range from 80 ± 6 mmHg in baseline, to 107 ± 9 mmHg during isometric handgrip maneuvers. Agreement between reference and chest-sensor MAP values was tested by using intraclass correlation coefficient (ICC = 0.78) and Bland-Altman analysis (mean error = 0.7 mmHg, standard deviation = 5.1 mmHg). The cumulative percentage of MAP values provided by the chest sensor falling within a range of ±5 mmHg compared to reference MAP readings was of 70%, within ±10 mmHg was of 91%, and within ±15mmHg was of 98%. These results point at the fact that the chest sensor complies with the British Hypertension Society (BHS) requirements of Grade A BP monitors, when applied to MAP readings. Grade A performance was maintained even two weeks after having performed the initial subject-dependent calibration. In conclusion, this paper introduces a sensor and a calibration strategy to perform MAP measurements at the chest. The encouraging performance of the presented technique paves the way towards an ambulatory-compliant, continuous and non-occlusive BP monitoring system.

Noninvasive visualization of coronary artery endothelial function in healthy subjects and in patients with coronary artery disease.

OBJECTIVES: The goal was to test 2 hypotheses: first, that coronary endothelial function can be measured noninvasively and abnormal function detected using clinical 3.0-T magnetic resonance imaging (MRI); and second, that the extent of local coronary artery disease (CAD), in a given patient, is related to the degree of local abnormal coronary endothelial function. BACKGROUND: Abnormal endothelial function mediates the initiation and progression of atherosclerosis and predicts cardiovascular events. However, direct measures of coronary endothelial function have required invasive assessment. METHODS: The MRI was performed in 20 healthy adults and 17 patients with CAD. Cross-sectional coronary area and blood flow were quantified before and during isometric handgrip exercise, an endothelial-dependent stressor. In 10 severe, single-vessel CAD patients, paired endothelial function was measured in the artery with severe stenosis and the contralateral artery with minimal disease. RESULTS: In healthy adults, coronary arteries dilated and flow increased with stress. In CAD patients, coronary artery area and blood flow decreased with stress (both p </= 0.02). In the paired study, coronary artery area and blood flow failed to increase during exercise in the mildly diseased vessel, but both area (p = 0.01) and blood flow (p = 0.02) decreased significantly in the severely diseased, contralateral artery. CONCLUSIONS: Endothelial-dependent coronary artery dilation and increased blood flow in healthy subjects, and their absence in CAD patients, can now be directly visualized and quantified noninvasively. Local coronary endothelial function differs between severely and mildly diseased arteries in a given CAD patient. This novel, safe method may offer new insights regarding the importance of local coronary endothelial function and improved risk stratification in patients at risk for and with known CAD.

Regional coronary endothelial function is closely related to local early coronary atherosclerosis in patients with mild coronary artery disease: pilot study.

BACKGROUND: Coronary endothelial function is abnormal in patients with established coronary artery disease and was recently shown by MRI to relate to the severity of luminal stenosis. Recent advances in MRI now allow the noninvasive assessment of both anatomic and functional (endothelial function) changes that previously required invasive studies. We tested the hypothesis that abnormal coronary endothelial function is related to measures of early atherosclerosis such as increased coronary wall thickness. METHODS AND RESULTS: Seventeen arteries in 14 healthy adults and 17 arteries in 14 patients with nonobstructive coronary artery disease were studied. To measure endothelial function, coronary MRI was performed before and during isometric handgrip exercise, an endothelial-dependent stressor, and changes in coronary cross-sectional area and flow were measured. Black blood imaging was performed to quantify coronary wall thickness and indices of arterial remodeling. The mean stress-induced change in cross-sectional area was significantly higher in healthy adults (13.5%±12.8%, mean±SD, n=17) than in those with mildly diseased arteries (-2.2%±6.8%, P<0.0001, n=17). Mean coronary wall thickness was lower in healthy subjects (0.9±0.2 mm) than in patients with coronary artery disease (1.4±0.3 mm, P<0.0001). In contrast to healthy subjects, stress-induced changes in cross-sectional area, a measure of coronary endothelial function, correlated inversely with coronary wall thickness in patients with coronary artery disease (r=-0.73, P=0.0008). CONCLUSIONS: There is an inverse relationship between coronary endothelial function and local coronary wall thickness in patients with coronary artery disease but not in healthy adults. These findings demonstrate that local endothelial-dependent functional changes are related to the extent of early anatomic atherosclerosis in mildly diseased arteries. This combined MRI approach enables the anatomic and functional investigation of early coronary disease.

Administration of growth hormone to underweight patients with chronic obstructive pulmonary disease. A prospective, randomized, controlled study.

Patients with chronic obstructive pulmonary disease (COPD) often develop weight loss, which is associated with increased mortality. Recombinant human growth hormone (rhGH) treatment has been proposed to improve nitrogen balance and to increase muscle strength in these patients. The aim of this study was to assess the effects of rhGH administration on the nutritional status, resting metabolism, muscle strength, exercise tolerance, dyspnea, and subjective well-being of underweight patients with stable COPD. Sixteen patients attending a pulmonary rehabilitation program (age: 66 +/- 9 yr; weight: 77 +/- 7% of ideal body weight; FEV1: 39 +/- 13% of predicted) were randomly treated daily with either 0.15 IU/kg rhGH or placebo during 3 wk in a double-blind fashion. Measurements were made at the beginning (DO) and at the end (D21) of treatment and 2 mo later (D81). Body weight was similar in the two groups during the study, but lean body mass was significantly higher in the rhGH group at D21 (p < 0.01) and D81 (p < 0.05). The increase in lean body mass was 2.3 +/- 1.6 kg in the rhGH group and 1.1 +/- 0.9 kg in the control group at D21 and 1.9 +/- 1.6 kg in the rhGH group and 0.7 +/- 2.1 kg in the control group at D81. At D21, the resting energy expenditure was increased in the rhGH group (107.8% of DO, p < 0.001 compared with the control group). At D21 and D81, the changes in maximal respiratory pressures, handgrip strength, maximal exercise capacity, and subjective well-being were similar in the two groups. At D21, the 6-min walking distance decreased in the rhGH group (-13 +/- 31%) and increased in the control group (+10 +/- 14%; p < 0.01). We conclude that the daily administration of 0.15 IU/kg rhGH during 3 wk increases lean body mass but does not improve muscle strength or exercise tolerance in underweight patients with COPD.

Physical determinants of tennis performance in competitive teenage players

It is unclear how physical attributes influence tennis-specific performance in teenage players. The aims of this study were (a) to examine the relationships between speed, explosive power, leg stiffness, and muscular strength of upper and lower limbs; and (b) to determine to what extent these physical qualities relate to tournament play performance in a group of competitive teenage tennis players. A total of 12 male players aged 13.6 +/- 1.4 years performed a series of physical tests: a 5-m, 10-m, and 20-m sprint; squat jump (SJ); countermovement jump (CMJ); drop jump (DJ); multi-rebound jumps; maximum voluntary contraction of isometric grip strength; and plantar flexor of the dominant and nondominant side. Speed (r = 0.69, 0.63, and 0.74 for 5-, 10-, and 20-m sprints, respectively), vertical power abilities (r = -0.71, -0.80 and -0.66 for SJ, CMJ, and DJ, respectively), and maximal strength in the dominant side (r = -0.67 and -0.73 for handgrip and plantar flexor, respectively) were significantly correlated with tennis performance. However, strength in the nondominant side (r = -0.29 and -0.42 for handgrip and plantar flexor) and leg stiffness (r = -0.15) were not correlated with the performance ranking of the players. It seems that physical attributes have a strong influence on tennis performance in this age group and that an important asymmetry is already observed. By monitoring regularly such physical abilities during puberty, the conditioning coach can modify a program to compensate for the imbalances. This would in turn minimize the risks of injuries during this critical period.

National survey of noncommunicable diseases in Seychelles 2013‐2014 (Seychelles Heart Study IV) : main findings

The 2013 survey addressed the following objectives: Primary objectives : a) Distribution of health behaviors related to NCDs, particularly tobacco use, alcohol drinking, and physical activity ; b) Distribution of the main modifiable risk factors of NCDs, particularly blood pressure, adiposity markers, diabetes and blood lipids ; c) Rates of awareness, treatment and control of hypertension, diabetes and dyslipidemia ; d) Comparison of findings in the survey 2013 with results in previous similar NCD surveys in 1989, 1994, 2004 ; e) Dietary patterns ; f) Knowledge, attitudes and practices related to NCDs and NCD risk factors. Secondary objectives : g) Assessment of indicators of quality of health (e.g. SF‐12) ; h) Assessment of psychological stress and relation with NCD ; i) Assessment of several indicators of frailty (e.g. handgrip strength test, chair strand test, functional limitations) ; j) Assessment of knowledge and level of agreement with current policies on tobacco control ; k) Use of public and private health care services, particularly for NCDs ; l) Exposure to advice on health behaviors given by health professionals at health care level ; m) Burden of chronic diseases not related to the main NCDs (e.g. musculoskeletal, mental health, etc) ; n) Screening of selected cancers ; o) Assessment of the kidney function ; p) Frequency of heart arrhythmias (one‐lead ECG) and heart murmurs (auscultation) ; q) Assessment of bone mineral density (ultrasound of calcaneus) ; r) Exposure of the population to mass media, particularly in relation to health programs, and use by the population of new communication technologies ; s) Assessment of a number of social variables and their association with the variables measured in the survey ; t) More generally, the survey provides broad information (medical, social, environment, etc) that can be useful for tailoring NCD prevention and control programs.