0266

STUDY OF SYMPATHETIC ACTIVITY IN TETRALOGY OF FALLOT PATIENTS WITH CYANOTIC SPELLS

Wang Rongfa¹, Zhu Yueniu, Gao Wei, Zhou Aiqing ¹,

Xinhua Hospital, Shanghai Children’s Medical Center affiliated with Shanghai Second Medical University, Shanghai, China

Objective: Tetralogy of Fallot (TOF) is a common congenital cardiac defect. The treatment of cyanotic spells is one of the most challenging aspects in the management of these patients before surgical repair. The mechanism underlying the development of cyanotic spells has not been clearly defined. We hypothesized that excessive βAR stimulation of right ventricular infundibulum by catecholamine leading to hypercontractility contributes to the spells.

Methods: As the cyanotic spells in TOF patients often result from the cardiac catheterization, we studied the right ventricular plasma catecholamine (epinephrine, E; norepinephine,NE and dopamine,DA) levels of these patients just before and after the catheterization. And the data were divided into two groups based on the presence of the spell within 15 minutes after the catheterization when environmental other factors were similar. All plasma catecholamine levels were determined by high performance liquid chromatography with electrochemical detection (HPLC-EC).

Results: We studied 30 TOF patients: 15 cases with cyanotic spells while 15 cases without spells. The mean age is similar (with spell, 17.22±7.95months vs. without spell, 19.11±9.23months, p>0.05). The differences between the preoperative catecholamine (E, NE, DA ) levels of the two groups were not significant. Just after the catheterization the catecholamine levels of two groups both increased. And that in the cyanotic spell patients, the postoperative NE levels increased significantly (preoperative, 110.26±42.07 pg/ml vs. postoperative, 152.54±71.68 pg/ml; P<0.05) when no significant promotion found in the patients without spells. The same increase of E level was also found in the spell group (preoperative, 117.05±36.11 pg/ml vs. postoperative, 159.27±69.78 pg/ml; P<0.05).

Conclusion: These data demonstrate an up-regulation of regional sympathetic activity in the right ventricular which results in excessive βAR stimulation of right ventricular infundibulum leading to the present of spells within 15 minutes after catheterization. On-going research is necessary to discover the mechanism of this excessive sympathetic regulation.