Možganskožilna reaktivnost pri bolnikih s hudo aortno stenozo

Ovsenik, Ana (author), Fabjan, Andrej (mentor), Podbregar, Matej (comentor)

Izhodišča: Za aortno stenozo (AS) je značilna obstrukcija iztoka krvi iz levega prekata, ki lahko povzroči motnjo prekrvavitve tarčnih organov, vključno z možgani. V raziskavi smo predpostavili, da hemodinamske motnje pri AS povzročijo okvaro v delovanju mehanizmov regulacije možganskega krvnega pretoka (MKP). Namen naše raziskave je bil ovrednotiti živčnožilno sklopitev pri bolnikih s hudo AS s pomočjo transkranialnega doplerskega ultrazvoka (TKD). Metode: Živčnožilno sklopitev smo ovrednotili s pomočjo neinvazivnega merjenja vidnih evociranih odgovorov hitrosti krvnega toka (VEOHT), ki predstavljajo relativne spremembe hitrosti toka krvi v zadnji možganski arteriji ob vidnem draženju. Pri 54 bolnikih z AS in 43 kontrolnih preiskovancih smo v 10 zaporednih ciklih vidnega draženja analizirali največje sistolne, končne diastolne in srednje VEOHT. VEOHT smo med skupinama primerjali z metodo ponavljajočih meritev ANOVA. Povezavo med utripnim volumnom srca, indeksiranim na telesno površino (UVi), in VEOHT smo vzpostavili s Pearsonovo analizo korelacije. Rezultati: Bolniki z AS so imeli značilno višje največje sistolne (12,9% ± 5,6% in 10,5% ± 4,5%; p= 0,009) in srednje VEOHT (14,4% ± 5,8% in 12,2% ± 4,9%; p= 0,021) kot kontrolni preiskovanci, medtem ko so bile končne diastolne hitrosti le neznačilno višje (16,7% ± 6,9% and 14,4% ± 6,2%; p= 0,061). Dokazali smo negativno korelacijo med UVi in največjimi sistolnimi (K -0,336, p= 0.022), srednjimi (K -0,354, p= 0,016) kot tudi končnimi diastolnimi VEOHT (K -0,325, p= 0,028). Zaključek: To je prva raziskava, ki je dokazala, da imajo bolniki s hudo AS višje VEOHT kot kontrolni preiskovanci. Poleg tega so pri bolnikih z AS nižje vrednosti UVi povezane z višjimi VEOHT. Višje vrednosti VEOHT pri bolnikih z AS kažejo na hiperregulacijo živčnožilne sklopitve zaradi ovire v iztoku krvi iz levega prekata, ki lahko sčasoma vodi v izčrpanje mehanizmov regulacije MKP, motnjo v delovanju nevronov in kognitivni upad.

• Language: Slovenian
• Keywords: aortna stenoza, možganoskožilna reaktivnost, možganski krvni pretok, trankranialni doplerski ultrazvok, živčnožilna sklopitev
• Work type: Doctoral dissertation
• Organization: MF - Faculty of Medicine
• Year: 2024
• PID: 20.500.12556/RUL-155328
• Publication date in RUL: 27.03.2024

Secondary language

• Language: English
• Title: Cerebrovascular reactivity in patients with severe aortic valve stenosis

Abstract

Background: Aortic stenosis (AS) is characterized by obstruction of blood outflow from the left ventricle, which can impair target organ perfusion such as the brain. We hypothesized that hemodynamic changes in AS may lead to dysfunction of cerebral blood flow (CBF) regulatory mechanisms. The aim of our study was to evaluate neurovascular coupling (NVC) in severe AS by Transcranial Doppler Ultrasound (TCD). Methods: NVC was assessed using visually evoked cerebral blood flow velocity responses (VEFR) calculated as relative velocity changes in the posterior cerebral artery upon visual stimulation. We analysed peak systolic, mean and end-diastolic VEFR in 54 patients with severe AS, and 43 controls in 10 consecutive cycles of visual stimulation. Repeated-measures ANOVA test was used to compare cerebral hemodynamic data by group. The association between stroke volume, indexed to body surface area (SVi), and VEFR was established using Pearson correlation analysis. Results: Patients with AS had significantly higher peak systolic (12.9% ± 5.6% and 10.5% ± 4.5%; p= 0.009) and mean VEFR (14.4% ± 5.8% and 12.2% ± 4.9%; p= 0.021) compared to controls, whereas only a tendency for higher end-diastolic VEFR was observed (16.7% ± 6.9% and 14.4% ± 6.2%; p= 0.061). A negative correlation between SVi and peak systolic (K -0.336, p= 0.022), mean (K -0.354, p= 0.016) as well as end-diastolic VEFR (K -0.325, p= 0.028) was established. Conclusion: We have shown for the first time that patients with severe AS exhibit higher VEFR than controls. Furthermore, in patients with AS, lower values of SVi are associated with higher VEFR. This may indicate hyperregulation of NVC in AS due to the obstruction of blood outflow from the left ventricle. In time, this can lead to exhaustion of compensatory mechanisms of CBF regulation, impairment of neuronal metabolism and result in cognitive decline.

• Keywords: aortic stenosis, cerebrovascular reactivity, cerebral blood flow, transcranial doppler ultrasound, neurovascular coupling