Сolor Doppler Imaging in Eye Hemodynamics Evaluation in Syndrome of Thrombotic Microangiopathy

Abstract

Purpose.To assess the state of blood flow in retrobulbar vessels using the method of color Doppler imaging in thrombotic microangiopathy (TMA) associated with atypical hemolytic uremic syndrome (aHUS), malignant hypertension (MH) and catastrophic antiphospholipid syndrome (CAPS).Methods. The study involved 16 patients aged from 18 to 43 years with TMA associated with aHUS (13 patients), MH (2 patients) and CAPS (1 patient). All patients underwent a study of the state of blood flow in the vessels of the retrobulbar space by color Doppler imaging using a multifunctional ultrasonic diagnostic device Voluson 730 Pro and Voluson E8. The spectrum of blood flow in the ophthalmic artery (OA), central retinal artery (CRA), central retinal vein (CRV), in the medial and lateral short posterior ciliary arteries (SPCA) was recorded and the following parameters were determined: maximum systolic velocity (Vsyst), final diastolic velocity (Vdiast), peripheral resistance index (RI), pulsation index (PI).Results. The analysis of the Doppler blood flow spectrum in all patients with TMA syndrome revealed a decrease in Vsyst in the vessels of the retrobulbar space, more pronounced in the CRA, with an increase in the venous component of the Doppler spectrum. In patients with TMA associated with aHUS and MH Vdiast in the studied vessels were in normal limits or increased, RI and PI were reduced. In aHUS a statistically significant correlation was found between Vdiast in OA and the level of haptoglobin in blood serum, which is a classic marker of intravascular hemolysis.Conclusion. Color Doppler imaging of retrobulbar vessels is an important method for the diagnosis of ocular hemodynamics disorders in the syndrome of TMA. All patients with TMA syndrome are characterized with a decrease in the systolic component of the Doppler spectrum of blood flow in the vessels of the retrobulbar space, especially in the CRA, with an increase in the venous component. With aHUS and MH diastolic blood flow in the retrobulbar vessels corresponds to the norm or increases, RI and PI decrease. In TMA associated with aHUS, the final diastolic velocity of blood flow in OA depends on the level of microvascular  hemolysis.