Incidence and Mechanism of Post Carotid Endarterectomy Hypertension

Post-endarterectomy hypertension (PEH) is associated with intracranial haemorrhage (ICH), hyperperfusion syndrome stroke and cardiac complications. Whilst well recognised, its pathophysiology is poorly understood. It was hypothesised that pre-operative poorly controlled blood pressure, baroreceptor dysfunction and impairment of cerebral autoregulation might be associated with PEH. Our aim was to investigate these and other pre-operative clinical variables which may be predictive of those who suffer PEH. 106 patients undergoing carotid endarterectomy (CEA) underwent investigations to evaluate the pathophysiology of PEH including; 24-hour ambulatory BP, central aortic BP, baroreceptor sensitivity (BRS), cerebral autoregulation and transcranial Doppler (TCD) measurement of middle cerebral artery blood flow velocity (MCAV); Clinical details, BP readings from the ward, induction of anaesthesia and during surgery, mode of anaesthesia, vasoactive medications and MCAV changes following flow restoration. Patients with PEH (defined as systolic pressure (SBP)>170mmHg + no symptoms or >160mmHg with headache/seizure/deficit) were treated according to Unit guidelines. 40/106 required treatment for PEH (26 in recovery, 27 on the ward), while 7 had surges in SBP>200mmHg on the ward. PEH (recovery/ward) was not associated with pre-operative patient characteristics or TCD variables and was not associated with impaired autoregulation (autoregulation was better preserved in PEH patients (ARI 4.3 +/-1.4 vs. ARI 3.5 +/-1.6 (p=0.03)). PEH was significantly associated with; (i) higher pre-operative BP (peak SBP>170mmHg = 59% prevalence); (ii) peak SBP>170mmHg before induction of anaesthesia (61% prevalence) and (iii) impaired BRS (3.4 +/- 1.7ms/mmHg vs. 5.3 +/-2.8ms/mmHg, p=0.001). Length of stay was significantly increased in PEH patients (p<0.001), while three patients with temporary headache/seizure/deficit and one with delayed ICH required treatment for PEH (p=0.02). PEH was associated with pre-operative poorly controlled BP and impairment of baroreceptor sensitivity. Cerebral autoregulation was better preserved in those who suffered PEH. Within the time constraints of carrying out surgery in the hyper acute period, it is neither achievable nor advisable to aggressively optimise blood pressure prior to surgery. For now the optimal management remains an uncompromising approach to treating PEH.