Intima-Media-Dicke – ein wichtiger subklinischer Atheroskleroseparameter

Abstract

Intima-media thickness (IMT) of the carotid artery is defined as a double layer visible in B-mode ultrasound as part of the arterial wall. Due to its low measurement variability (intra- and inter-observer) and high visibility, the measurement is strongly recommended in the most distal part of the common carotid artery. Reading should preferably be done by automated tracing because it shows significantly lower reading variability than manual procedures. In addition, in depth training is a prerequisite for reproducible and reliable IMT measurements.

IMT increases linearly with age and is concordantly associated with most of the atherosclerotic risk factors responsible for cardio-vascular events, i. e. myocardial infarction or stroke. In addition, IMT of the carotid arteries is an independent predictor of cardio-vascular events, even after adjustments for atherosclerotic risk factors. IMT measurements of the carotid tree are most useful for assessing CVD risk in intermediate risk patients and special risk groups. Plaques in the carotid tree and IM thickening are independent atherosclerotic processes. IM thickening may occur early in life, at which point plaques are not yet visible. Both contribute independently to the risk assessment of future cardio-vascular events.

Kernaussagen

• Die Messung der Intima-Media-Dicke der Karotiden ist sicher, kostengünstig und verlässlich einsetzbar, um die atherosklerotische Last abzuschätzen.

• Die IMT leistet einen unabhängigen Beitrag zur Abschätzung des kardiovaskulären Risikos bei asymptomatischen Patienten mit klassischen atherosklerotischen Risikofaktoren.

• Die IMT steigt auch bei Gesunden mit zunehmendem Lebensalter an. Diese altersbezogene Progression ist von beschleunigter Progression durch eine erhöhte Risikofaktorenbelastung oder manifeste atherosklerotische Erkrankung abzugrenzen.

• Wegen der besten Sichtbarkeit, der Einfachheit der Messung, der besten Reproduzierbarkeit und vergleichbarer prädiktiver Bedeutung wie im restlichen Karotisbaum sollte die IMT vorzugsweise im distalen Zentimeter der A. carotis communis gemessen werden.

• Mindestvoraussetzung für die Messung ist ein 7,5 MHz linearer Schallkopf mit einer Breite von mindestens 3 cm.

• Die Standards der Messung sind strikt einzuhalten, um reproduzierbare und vergleichbare Messwerte zu erhalten.

• Unter den Analysemethoden der IMT haben die automatisierten Methoden die größte Reproduzierbarkeit und den kleinsten Lesefehler.

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