Background: 

Sudden cardiac death (SCD) is a common late complication in patients with tetralogy of Fallot (ToF). Reduced cardiovagal baroreflex sensitivity (BRS) was found to be an independent predictor of SCD. Reduced BRS was reported in ToF patients, but the underlying mechanism is not clear. Our laboratory has shown earlier that BRS is related to carotid artery distensibility (DC) in healthy subjects and that DC is reduced in ToF patients. Considering all above, we aimed to test the hypothesis that reduced BRS is related to impaired carotid artery elastic function.

Methods: 

We studied 36 ToF patients (21±11 yrs) and 50 age-matched healthy control subjects. Carotid artery diastolic diameter and pulsatile distension was determined by echo wall tracking and carotid blood pressure was measured by tonometry. DC was calculated subsequently. Spontaneous blood pressure fluctuations coupled with adequate heart rate responses were used to calculate spontaneous BRS (sBRS). Intravenous phenylephrine-induced blood pressure elevation followed by heart rate reduction was used to determine BRSphe.

Results: 

(mean±SD) BRS indices were markedly reduced in patients compared with controls (sBRS 9.3±9.2 vs. 17.5±6.8 ms/mmHg; BRSphe 16.8±10.2 vs. 32.6±11.4 ms/mmHg). DC also showed significant difference between groups (5.1±1.8 vs. 6.8±2.8 10–3/mmHg). DC correlated significantly and positively with BRS across patients and control subjects as well (sBRS r=0.49†vs. r=0.42*; BRSphe r=0.31 vs. r=0.73*). Multiple regression analysis indicated that DC is an independent determinant of BRS indices in ToF patients. (†:p<0.05; *:p<0.01)

Discussion: 

Our data demonstrate that reduced DC can contribute to impairment of BRS in ToF patients. Lifestyle modifications, such as moderate aerobic exercise, sodium restriction and omega-3-fatty acid intake, appear to be efficient interventions in preventing and treating carotid artery stiffness and – indirectly – impaired baroreflex function.