Evaluation of intracranial circulation in patients in terminal stage of heart failure before and after heart transplantation BRAIN-SAVE 2

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Abstract Background and Aims Patients with chronic heart failure in the terminal stage suffer from chronic organ hypoperfusion, which also affects the brain, despite the activation of adaptation mechanisms. This results in impaired autoregulation of cerebral circulation, expressed as a deterioration in cerebrovascular reactivity (CVR) as well as cognitive function (1,2). Orthotopic heart transplantation (OHT) is followed by a rapid and sudden restoration of cardiac output along with subsequent improvement in cerebral perfusion and cognitive function (3-5). A sudden rise in cerebral perfusion pressure can simultaneously lead to neurological complications in the early postoperative period, specifically the potential development of cerebral hyperperfusion syndrome (CHS). An important risk factor for the development of CHS is impairment of cerebrovascular reactivity in the preoperative period (6). The primary aim of presented study was to evaluate cerebrovascular reactivity in patients indicated for heart transplantation compared to subjects from a control group, and also to monitor CVR development 1 month and 6 months after heart transplantation. The secondary aim of the study was to evaluate other haemodynamic parameters before OHT as well as 24-48 hours, 1 month, and 6 months after OHT. We presented first results of the study previously (7). Now we have complete results to be presented and published. Methods Monitored parameters were evaluated by transcranial colour-coded duplex sonography (TCCS). An apnoea test was performed to determine the breath-holding index (BHI) as a parameter of cerebrovascular reactivity. The measurement was performed in the M1 segment of the middle cerebral artery. CVR was evaluated in all patients before transplantation (group A, n=10) and 1 month and 6 months after transplantation (group B, n=9). Other haemodynamic parameters (secondary endpoints of follow-up) were evaluated before OHT as well as 24-48 hours, 1 month, and 6 months after OHT. The control group consisted of 16 healthy volunteers. Results (primary endpoint) Cerebrovascular reactivity was reduced preoperatively in all but one heart transplantation candidates; it was normal in all control subjects. There was a significant difference in BHI between the OHT candidate group and the control group (0.29 vs. 0.96, p<0,0001), indicating a significant impairment of CVR in OHT candidates. Six months after OHT, there was a significant increase in the BHI value compared to the preoperative value (0.29 vs. 1.06, p=0.009), pointing to CVR restoration. Contrary to our preliminary results, there were significant increase of BHI also one month after OHT (0.29 vs. 0.04, p=0.04), pointing to an early post OHT restoration of CVR. Conclusions Cerebrovascular reactivity was significantly reduced in heart transplant candidates. However, this impairment proved reversible, with restoration as early as one month after OHT and this remaind six month after heart transplantation.

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