Evaluation of cognitive functions in elderly patients undergoing transcatheter aortic valve implantation under deep sedationinvestigation of near infra-red spectroscopy monitoring efficiency

Objectives: Aortic stenosis (AS) is a common heart valve disease in the geriatric patient population and may have fatal consequences if left untreated. Transcatheter aortic valve implantation (TAVR) has become a standard treatment for patients with AS, offering a reasonable alternative for high-risk patients. In recent years, there has been a shift from general anesthesia towards sedation and local anesthesia in the anesthesia management, which is an important part of the TAVI procedure. A safe anesthesia approach should ensure adequate tissue perfusion and oxygenation. Technological advancements have provided continuous monitoring methods for tissue perfusion and oxygenation. One of these technologies, Near-infrared spectroscopy (NIRS), can non-invasively and continuously measure the oxygenation of both cerebral hemispheres in patients undergoing TAVI. This study aims to investigate the effectiveness of NIRS monitoring in evaluating cognitive function in elderly patients undergoing TAVI under deep sedation. Materials and Methods: This study is a single-center, prospective, observational study conducted with patients undergoing TAVI at Samsun Ondokuz Mayıs University Medical Faculty Hospital with local ethics committee approval. In the preoperative evaluations, patients' Euroscore II values, ASA scores, and TAVI frailty scores were calculated and recorded. Laboratory values (hemoglobin, BUN, creatinine, fasting blood glucose) were recorded 48 hours before and after the procedure. Cognitive tests were performed using the Modified Mini-Mental State Examination (MMSE). The test was administered face-to-face by a specially trained physician. The MMSE was conducted twice, 48 hours before and 48 hours after the procedure. Patients scoring 16 or above on the pre-TAVI test were included in the study. A total of 25 patients participated in the study. Cerebral desaturation was defined as a decrease of 20% or more in the NIRS value compared to the baseline rSO2 value in either the right/left hemisphere or both hemispheres at any time during the procedure, and patients were divided into two groups: those with developing cerebral desaturation (decrease of more than 20%) and those without developing cerebral desaturation (decrease of less than 20%). Routine monitoring included invasive arterial blood pressure measurement (systolic, diastolic, and mean arterial pressure) via the radial artery, heart rate, peripheral oxygen saturation (SpO2), regional cerebral oxygen saturation (rSO2) measured from the frontal region using right and left probes, end-tidal CO2 value (etCO2), procedure duration, drug doses, and fluid administration. Regional cerebral oxygenation was measured using NIRS (Invos, Medtronic, USA®) device. Results: There were no significant differences between the groups in terms of gender, age, education, ASA, Euroscore II, TAVI Frailty Index, comorbidities, and drug doses. However, it was observed that the procedure duration was significantly longer in the group with developing desaturation. During the TAVI procedure, it was determined that systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, rSO2 values in the right and left hemispheres during the rapid ventricular pacing (RVP) phase were significantly lower compared to other phases. Additionally, it was found that the heart rate during the pace trial was significantly higher compared to other phases. On the other hand, during the RVP phase, the rSO2 values in the right and left hemispheres were significantly lower in the group with developing desaturation compared to the group without developing desaturation. In other phases, there were no significant differences in hemodynamic and cerebral oxygenation values between the groups. Finally, it was determined that both preoperative and postoperative MMSE scores did not show significant differences between the groups with developing desaturation and those without developing desaturation. Conclusions: NIRS monitoring was effective in demonstrating cerebral oxygen desaturation due to hemodynamic changes. However, these changes did not cause a change in the postoperative cognitive functions of the patients. Key words: Aortic stenosis, transcatheter aortic valve implantation, near-infrared spectroscopy, sedation, cognitive function.