Compressibility of the carotid artery in patients with pseudoxanthoma elasticum

The arterial wall has generally been considered as noncompressible in in vi tro studies. However, compressibility of the arterial wall (CAW) has never been studied in vivo in humans. Large interstitial proteoglycans play a maj or role in sustaining the compression generated by pulsatile forces. The ai ms of the present study were to develop an experimental methodology for the assessment of CAW in vivo in humans and to study CAW in patients with pseu doxanthoma elasticum (PXE), a genetic disease characterized by proteoglycan accumulation and fragmented, swollen, and calcified elastic fibers in conn ective tissues. We studied 19 female patients with PXE and 15 normal female control subjects matched for age and blood pressure. A high-resolution ech o-tracking system was used for the continuous determination of internal dia meter and wall thickness at the site of the common carotid artery. Matrices of the radiofrequency signal were analyzed with a dedicated software to me asure carotid wall cross-sectional area every 4 milliseconds during 4 to 6 cardiac cycles. CAW was calculated as the stroke change in cross-sectional area. CAW was 44% higher in patients with PXE than in control subjects (6.8 +/-2.6% versus 4.7 +/-2.7%, respectively; P <0.05). In control subjects, C AW decreased with age in a linear manner (r = - 0.75, P <0.01). In PXE pati ents, the relationship with age was not homogeneous: CAW tended to increase with age before 40 years (P = 0.07) and significantly decreased with age i n older patients (P <0.01). Carotid geometry and elastic properties did not differ between PXE patients and control subjects. In conclusion, CAW was m easurable in vivo and noninvasively in humans. The higher CAW of PXE patien ts compared with that of control subjects suggests that proteoglycans are i mportant determinants of compressibility.