The effects of carotid endarterectomy on the mechanical properties of the carotid sinus and carotid sinus nerve activity in atherosclerotic patients

Abstract

The hypothesis that instability of blood pressure occurring afrer carotid endarterectomy is related to interference with mechanical properties of the arterial wall in the region of the carotid sinus was investigated in I I patients undergoing carotid surgery for transient ischaemic neurological disturbances. The operative procednre was found to change the mechanical properties of the arterial wall, there being an overall increase in diameter and reduction in distensibility, and these changes were reflected in the recorded change of spontaneous sinus nerve activity and the systemic blood pressure. It is suggested that the sinus nerve and carotid baroreceptor region should be carefully preserved duriizg carotid endarterectomy to prevent reflex postoperative hypertension. Shoidd hypotension occur in the postoperative phase it can be treated by local anaesthesia of the sinus region, anaesthetic blockade being maintained until secondary adaptation of the receptors takes place.

Effect of Carotid Endarterectomy or Stenting on Impairment of Dynamic Cerebral Autoregulation

“…Relative hypotension post-CEA has been observed previously and might be attributed to restituted flow at the carotid sinus baroreceptor site. 19,20 However, the ABP changes observed in our study are overall comparatively small and multiple regression modeling of the present data could not demonstrate a significant influence on restoration of cerebral autoregulatory parameters. It is thus unlikely that these factors have critically influenced the autoregulatory changes observed after carotid recanalization.…”

Spontaneous Indices Are Inconsistent With Arterial Baroreflex Gain

“…Decades of research in both humans and animals have clearly documented that induced arterial pressure increases and/or decreases result in afferent baroreceptor firing 36,46 and efferent baroreflex-mediated cardiac vagal outflow 47,48 that are proportional to the pressure changes. 49 The relation of the resultant bradycardia and/or tachycardia to pressure changes has been overwhelmingly supported as an appropriate measure of the sensitivity, or gain, of the cardiac vagal baroreflex.…”

Quantification of Mechanical and Neural Components of Vagal Baroreflex in Humans

“…In patients after endarterectomy, those with increased carotid sinus diameter had greater carotid sinus nerve activity and lower postoperative blood pressure. 26 Thus, excising carotid tissue altered the relation between pressure and diameter but not that between diameter and nervous activity. Although the only human data demonstrate a simple proportionality between carotid sinus dimensions and integrated carotid sinus nerve activity within the cardiac cycle, 6 animal data suggest a linear proportionality applies throughout broader pressure ranges.…”