Longterm peripheral baroreflex and chemoreflex function after bilateral eversion carotid endarterectomy
Creators: name: Marrocco Trischitta, Massimiliano Maria <1969>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2008
Subjects: MED/22 Chirurgia vascolare

description: Introduction
The “eversion” technique for carotid endarterectomy (e-CEA), that involves the
transection of the internal carotid artery at the carotid bulb and its eversion over the
atherosclerotic plaque, has been associated with an increased risk of postoperative
hypertension possibly due to a direct iatrogenic damage to the carotid sinus fibers. The
aim of this study is to assess the long-term effect of the e-CEA on arterial baroreflex
and peripheral chemoreflex function in humans.
Methods
A retrospective review was conducted on a prospectively compiled
computerized database of 3128 CEAs performed on 2617 patients at our Center between
January 2001 and March 2006. During this period, a total of 292 patients who had
bilateral carotid stenosis ≥70% at the time of the first admission underwent staged
bilateral CEAs. Of these, 93 patients had staged bilateral e-CEAs, 126 staged bilateral s-
CEAs and 73 had different procedures on each carotid.
CEAs were performed with either the eversion or the standard technique with
routine Dacron patching in all cases. The study inclusion criteria were bilateral CEA
with the same technique on both sides and an uneventful postoperative course after both
procedures. We decided to enroll patients submitted to bilateral e-CEA to eliminate the
background noise from contralateral carotid sinus fibers. Exclusion criteria were: age
&gt;70 years, diabetes mellitus, chronic pulmonary disease, symptomatic ischemic cardiac
disease or medical therapy with b-blockers, cardiac arrhythmia, permanent neurologic
deficits or an abnormal preoperative cerebral CT scan, carotid restenosis and previous
neck or chest surgery or irradiation. Young and aged-matched healthy subjects were
also recruited as controls.
Patients were assessed by the 4 standard cardiovascular reflex tests, including
Lying-to-standing, Orthostatic hypotension, Deep breathing, and Valsalva Maneuver.
Indirect autonomic parameters were assessed with a non-invasive approach based on
spectral analysis of EKG RR interval, systolic arterial pressure, and respiration
variability, performed with an ad hoc software. From the analysis of these parameters
the software provides the estimates of spontaneous baroreflex sensitivity (BRS).
The ventilatory response to hypoxia was assessed in patients and controls by
means of classic rebreathing tests.
Results
A total of 29 patients (16 males, age 62.4±8.0 years) were enrolled. Overall, 13
patients had undergone bilateral e-CEA (44.8%) and 16 bilateral s-CEA (55.2%) with a
mean interval between the procedures of 62±56 days.
No patient showed signs or symptoms of autonomic dysfunction, including
labile hypertension, tachycardia, palpitations, headache, inappropriate diaphoresis,
pallor or flushing. The results of standard cardiovascular autonomic tests showed no
evidence of autonomic dysfunction in any of the enrolled patients.
At spectral analysis, a residual baroreflex performance was shown in both
patient groups, though reduced, as expected, compared to young controls. Notably,
baroreflex function was better maintained in e-CEA, compared to standard CEA. (BRS
at rest: young controls 19.93 ± 2.45 msec/mmHg; age-matched controls 7.75 ± 1.24;
e-CEA 13.85 ± 5.14; s-CEA 4.93 ± 1.15; ANOVA P=0.001; BRS at stand: young
controls 7.83 ± 0.66; age-matched controls 3.71 ± 0.35; e-CEA 7.04 ± 1.99; s-CEA
3.57 ± 1.20; ANOVA P=0.001).
In all subjects ventilation (VÝ E) and oximetry data fitted a linear regression model
with r values &gt; 0.8. Oneway analysis of variance showed a significantly higher slope
both for ΔVE/ΔSaO2 in controls compared with both patient groups which were not
different from each other (-1.37 ± 0.33 compared with -0.33±0.08 and -0.29 ±0.13
l/min/%SaO2, p&lt;0.05, Fig.). Similar results were observed for and ΔVE/ΔPetO2 (-0.20 ±
0.1 versus -0.01 ± 0.0 and -0.07 ± 0.02 l/min/mmHg, p&lt;0.05). A regression model using
treatment, age, baseline FiCO2 and minimum SaO2 achieved showed only treatment as
a significant factor in explaining the variance in minute ventilation (R2= 25%).
Conclusions
Overall, we demonstrated that bilateral e-CEA does not imply a carotid sinus
denervation. As a result of some expected degree of iatrogenic damage, such
performance was lower than that of controls. Interestingly though, baroreflex
performance appeared better maintained in e-CEA than in s-CEA. This may be related
to the changes in the elastic properties of the carotid sinus vascular wall, as the patch is
more rigid than the endarterectomized carotid wall that remains in the e-CEA.
These data confirmed the safety of CEA irrespective of the surgical technique
and have relevant clinical implication in the assessment of the frequent hemodynamic
disturbances associated with carotid angioplasty stenting.