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Postischemic blood flow response in hypercholesterolemic patients
D Hayoz1, R Weber, B Rutschmann
1Division d'Hypertension, CHUV, Lausanne, Switzerland.
Insights
Hypercholesterolemia impairs forearm blood flow response to ischemia, but not radial artery function. Lipid-lowering therapy with simvastatin may restore this vascular response in hypercholesterolemic patients.
Area of Science:
- Vascular Physiology
- Cardiovascular Research
- Metabolic Disorders
Background:
- Hypercholesterolemia is a significant risk factor for cardiovascular disease.
- The impact of hypercholesterolemia on arterial mechanical behavior and postischemic vascular response requires further elucidation.
- Statins are widely used to manage hypercholesterolemia, but their specific effects on microvascular function need detailed study.
Purpose of the Study:
- To compare the mechanical properties and postischemic blood flow response of the radial artery in newly diagnosed hypercholesterolemic patients, normocholesterolemic controls, and hypercholesterolemic patients treated with simvastatin.
- To investigate whether simvastatin treatment improves vascular function in hypercholesterolemic individuals.
Main Methods:
- Cross-sectional study involving three groups: newly diagnosed hypercholesterolemic, normocholesterolemic controls, and simvastatin-treated hypercholesterolemic patients.
- High-resolution echotracking, Doppler ultrasound, and photoplethysmography were used to assess radial artery diameter, blood flow velocity, and blood pressure.
- Forearm blood flow and flow-mediated dilation were measured after a 5-minute upper arm occlusion.
Main Results:
- Radial artery cross-sectional compliance and distensibility were similar across all groups.
- Flow-mediated dilation after ischemia did not differ significantly among the three groups.
- Forearm blood flow increase post-ischemia was significantly blunted in untreated hypercholesterolemic patients compared to controls and treated patients.
Conclusions:
- Radial artery distensibility and flow-mediated dilation are preserved in hypercholesterolemia.
- Forearm resistance vessels show a reduced postischemic blood flow response in untreated hypercholesterolemia.
- Prolonged lipid-lowering intervention with simvastatin may restore impaired postischemic forearm blood flow response.
Abstract:
We undertook this cross-sectional study to compare the mechanical behavior and postischemic response of the radial artery of 15 newly diagnosed hypercholesterolemic patients with those of 15 age- and sex-matched normocholesterolemic control subjects and 21 hypercholesterolemic patients treated for 2 years with an 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (simvastatin, 10 to 20 mg/d). At the time of the study total cholesterol levels were at 7.9 +/- 0.2, 4.9 +/- 0.2, and 6.0 +/- 0.3 mmol/L in the three groups, respectively (mean +/- SEM, P < .001). High-resolution, noninvasive echotracking for assessment of internal arterial diameter was combined with measurements of blood flow velocity by Doppler and blood pressure by photoplethysmography. Radial cross-sectional compliance and distensibility were similar in all groups. Forearm blood flow and flow-mediated dilation were measured after a 5-minute upper arm occlusion. Flow was calculated from the vessel diameter and blood flow velocity recorded simultaneously at the same site. Flow-mediated dilation after ischemia was not significantly different among the three groups. However, forearm blood flow increase was markedly blunted (P < .01) in untreated hypercholesterolemic patients (211%) compared with the normocholesterolemic control subjects (411%) and treated patients (365%). These findings suggest that the distensibility of the radial artery, a muscular conduit vessel usually devoid of atherosclerotic lesions, and its flow-mediated dilation are preserved in hypercholesterolemic patients. In contrast, forearm resistance vessels exhibit a markedly reduced postischemic blood flow response that may be restored by prolonged lipid-lowering intervention.