Peripheral vascular structure and function in hypertrophic cardiomyopathy

Abstract

Background Hypertrophic cardiomyopathy (HCM) is characterised by idiopathic cardiac enlargement and represents the most frequent cause of sudden cardiac death in athletes under the age of 35 years. Differentiation between physiological (ie, exercise-related) and pathological (ie, HCM-related) cardiac remodelling is challenging. In line with cardiac remodelling, vascular structure and function are altered following training, but little is known about peripheral vascular adaptations in HCM. We hypothesised that, while HCM patients and athletes would exhibit similar cardiac characteristics, differences would be apparent in their brachial and carotid arteries. Methods In age-matched groups of HCM patients (n=18, 39±15 years), highly competitive athletes (n=18, 38±12 years) and recreational controls (n=10, 37 ±14 years), we used high-resolution ultrasound to assess the diameter and wall thickness of the carotid and brachial arteries, with flow-mediated dilator function (FMD) of the brachial arteries also assessed. Results A significant difference between athletes and HCM was evident in arterial wall thickness (carotid 519±60 vs 586±102 mm, p<0.05; brachial 345±80 vs 456±76 mm, p<0.05) and the brachial artery peak blood flow response following forearm ischaemia, an index of resistance artery remodelling (998±515 vs 725±248 ml/ min, p<0.05). Similar differences were noted between athletes and controls, while controls and HCM did not differ. Brachial FMD% was not different between groups. Conclusions Athletes and HCM subjects, who can be difficult to differentiate on the basis of cardiac measures, exhibit differences in indices of arterial structure. While this may be a disease-related effect, we cannot discount a generic impact of physical activity on arterial structure, as the athlete's arteries were also different to untrained control subjects. Future studies should assess artery function and structure in athletic HCM subjects.

Flow-Mediated Dilation in Athletes

“…Time to peak brachial diameter after cuff deflation was reported in one study (3). Shear rate parameters were reported in 15 studies (1,20,36,37,40,46,49,59), eight of which presented peak shear rate after cuff deflation (1,37,40,46) and seven presented area under the curve of shear rate until time of peak brachial diameter (20,36,49,59). Baseline brachial diameter ranged from 3.2 to 5.4 mm in the included studies.…”

“…As for the duration of blood flow occlusion, 23 studies used a 5-min period, whereas six studies reported periods between 4 and 5 min (1,23,27,44,50,56). Peak brachial diameter after cuff deflation (i.e., during hyperemia) was determined via continuous ultrasound scan in 20 studies (1,3,(12)(13)(14)20,27,36,40,49,50,59,60) and single time point(s) ultrasound scan in seven studies (23,29,32,(44)(45)(46)56), and one study did not report such information (37). Time to peak brachial diameter after cuff deflation was reported in one study (3).…”

“…It has been proposed that long-term training may result in the enlargement of conduit arteries, which in turn could reduce (normalize) the effect of shear stress on the endothelium and thus diminish the stimulus for FMD enhancement in athletes (20,30). Alternative explanations for the discrepant FMD results in athletes may lie in the inherent limitations of cross-sectional comparisons and the small sample sizes of previous individual studies (1,3,(12)(13)(14)20,23,27,29,32,36,37,40,(44)(45)(46)49,50,56,59,60). In addition, longitudinal studies have been predominantly based on relatively short-to medium-term training interventions, hence plausibly assessing incomplete vascular adaptations (53).…”

Cardiovascular Adaptations to Exercise Training

“…Most studies on the effect of endurance training on wall thickness suggests that wall thickness is reduced with training both in the forearm and leg (90,372,373,427) although an increased arterial wall thickness in parallel with an increase in arterial diameter has been reported (389).…”

Post‐contractile BOLD contrast in skeletal muscle at 7 T reveals inter‐individual heterogeneity in the physiological responses to muscle contraction

“…Post-contractile BOLD contrast has been used to characterize skeletal muscle function in healthy, sedentary, and active populations (1–3). Structural and functional changes in the microvasculature play a pivotal role in the pathogenesis of cardiovascular disease, hypertension, and diabetes (4,5). Therefore, muscle BOLD may be a powerful tool for measuring peripheral vascular function in individuals with peripheral arterial occlusive disease (6), obesity (7), and diabetes (7,8).…”