Systolic phases with laminar and turbulent flow in peripheral arteries of patients with congenital valvular aortic stenosis

Rationale: Blood flow passing a severe stenosis of the aortic valve becomes turbulent. This study aims to follow this turbulence along the arterial system studying the flow velocity at a high temporal resolution and investigating whether turbulence persists during the full duration of systole or whether parts of systole may show laminar flow.
Objective: to test whether turbulence persists during the whole or only during part of systole. Thereby this investigation tests the validity of the so-called theory of arterial acceleration which proposes that the first part of systole originates from a short-lasting stiffening of the muscular layers in the arterial tree and that the second part is due to the actual ejection of blood volume by the heart into the aorta.
Study design: observational follow up study
Study population: patients are recruited from the outpatient clinic of the UMCG cardiology department who are known to have no, moderate or severe aortic stenosis and are aged from 18 - 50 yrs. Each group will consist of 5 patients. Patients with atrial fibrillation are not eligible.
Intervention (if applicable): n.a.
Main study parameters/endpoints: main study parameter is presence of turbulence within the systolic phase of a blood flow velocity measurement and if so, during what part of systole
Nature and extent of the burden and risks associated with participation, benefit and group relatedness: subjects undergo two exams with approximately 3 months interval during which blood flow velocity signals are documented at different locations by duplex ultrasound investigation. The exams are non-invasive and without risk. The data collection is for scientific reasons only.

The aim of the present study is: can a single case observation of two distinct phases during systole (laminar and turbulent) be confirmed in other patients with aorta stenosis?

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