Features of the retinal structual and functional state under cardiopylmonary bypass during cardiac surgery

Abstract

Introduction. Cardiac surgeries using cardiopylmonary bypass (CB) have been successfully performed for more than 60 years, but at present it is necessary to further study the changes in tissue hemodynamics during interventions to minimize possible iatrogenic complications. One of these tissues available for direct observation of the vessels of the microvasculature is the retina. Aim – to study the structural and functional state of the retina in patients who underwent cardiac surgery with the use of CB, and to identify potential factors that negatively affect the retinal blood flow. Materials and methods. The clinical study involved 10 patients (20 eyes). All patients before cardiac surgery using CB and 10–14 days after it underwent visometry, perimetry, non-contact tonometry, biomicroscopy, reverse binocular ophthalmoscopy, fundus photography, optical coherence tomography of the retina of the macular region and optic nerve head with determination of the thickness of the layer of ganglion cell and the layer of nerve fibers. To carry out CB, pharmaco-cold cardioplegia was performed with the Custodiol solution using unified surgical and anesthetic tactics. CB was performed on a device with disposable membrane oxygenators (Strockert, Germany) under normothermic conditions, blood circulation was provided with non-pulsating blood flow with a volumetric flow rate of 2.4–2.8 L/min/m2 at an initial dose of heparin of 300 U/kg. Results. The studies revealed a correlation between changes in the histoarchitectonics of the retina and the level of mean arterial pressure (MAP). So, in 30 % of patients, the appearance of ischemic foci along the vascular arcades was found. In 10 % of patients, a decrease in the thickness of the ganglion layer and the layer of retinal nerve fibers was reported as a result of impaired blood circulation in the vessels supplying the optic nerve. Conclusion. Increase in MAP up to 90 mm Hg and above and fluctuations in its level of more than 20 mm Hg (p<0.05) during cardiac surgery under cardiopulmonary bypass in 67 % of cases is accompanied by transient disturbance of regional blood circulation at the level of vessels of the microvasculature of the retina with the appearance of ischemic foci in the retinal tissue. In this regard, it is necessary to carefully monitor the MAP parameters during the cardiopulmonary bypass to prevent circulatory disorders in various organs and tissues of the body.