The current strategy of repair of tetralogy of Fallot in children and adults.

OBJECTIVES: The strategies of repair of tetralogy of Fallot change with the age of patients. In children older than 4 years and adults, the optimal strategy may be to use different method of reconstruction of the right ventricular outflow tract from those followed in younger children, so as to avoid, or reduce, the pulmonary insufficiency that is increasingly known to compromise right ventricular function. METHODS: From April, 2001, through May, 2008, we undertook complete repair in 312 patients, 180 male and 132 female, with a mean age of 11.3 years +/-0.4 years, and a range from 4 to 48 years, with typical clinical and morphological features of tetralogy of Fallot, including 42 patients with the ventriculo-arterial connection of double outlet right ventricle. The operation was performed under moderate hypothermia using blood cardioplegia. The ventricular septal defect was closed with a Dacron patch. When it was considered necessary to resect the musculature within the right ventricular outflow tract, or perform pulmonary valvotomy, we sought to preserve the function of the pulmonary valve by protecting as far as possible the native leaflets, or creating a folded monocusp of autologous pericardium. RESULTS: The repair was achieved completely through right atrium in 192, through the right ventricular outflow tract in 83, and through the right atrium, the outflow tract, and the pulmonary trunk in 36 patients. A transjunctional patch was inserted in 169 patients, non-valved in all but 9. There were no differences regarding the periods of aortic cross-clamping or cardiopulmonary bypass. Of the patients, 5 died (1.6%), with no influence noted for the transjunctional patch. Of those having a non-valved patch inserted, three-tenths had pulmonary regurgitation of various degree, while those having a valved patch had minimal pulmonary insufficiency and good right ventricular function postoperatively, this being maintained after follow-up of 8 to 24-months. CONCLUSIONS: Based on our experience, we suggest that the current strategy of repair of tetralogy of Fallot in older children and adults should be based on minimizing the insertion of transjunctional patches, this being indicated only in those with very small ventriculo-pulmonary junctions. If such a patch is necessary, then steps should be taken to preserve the function of the pulmonary valve.

[Delayed disappearance of h-VEGF165 mRNA and protein under regulation of hypoxic response element].

Transfer of vascular endothelial growth factor (VEGF) gene to ischemic myocardium may provide a useful approach for angiogenesis and improve cardiac performance. However, uncontrolled expression of VEGF in vivo may result in certain side effects, such as hemangioma formation, retinopathy, and tumor development. We investigated the feasibility of using the nine copies of hypoxic response element (HRE) to control the expression of human VEGF(165) (h-VEGF(165)) under anoxic condition at cell level and also observed the synchron of h-VEGF(165) mRNA and protein expressions. Recombinant adeno-associated viral (rAAV) vector was prepared by using the three-plasmid system and cotransfected to human embryo kidney 293T cells by the calcium phosphate precipitates method. The rAAV vector was purified by chloroform-PEG8000/NaCl-chloroform and added to cultured myocardiocytes. Myocardiocytes of Sprague-Dawley rat were cultured in serum-free medium and then randomly divided into eight groups. Group I: cultured under normoxic conditions (21% O2) for 8 h as control; Group II: cultured under anoxic conditions (1% O2) for 8 h; Group III: cultured under normoxic conditions (21% O2) for 8 h with gene transfer; Group IV: cultured under anoxic conditions (1% O2) for 8 h with gene transfer; Group V, VI, VII: cultured under anoxic conditions (1% O2) for 8 h with gene transfer and then tured to normoxic conditions (21% O2) for 4, 8 or 12 h, respectively; Group VIII: cultured under anoxic conditions (1% O2) for 20 h with gene transfer. After completion of cell culture, the amount of h-VEGF(165) protein in culture supernatant was quantified by using enzyme linked immunosorbent assay (ELISA). Expression of h-VEGF(165) protein in cultured cardiacmyocytes was also evaluated by immunofluorescence. RT-PCR was employed to detect the expression of h-VEGF(165) mRNA. The results revealed that there were no expressions of h-VEGF(165) mRNA and protein in groups I, II, III, VI and VII. After gene transfer, the expressions of h-VEGF(165) protein and mRNA were significantly higher in groups IV and VIII than those in other groups (P<0.01); Immunofluorescence positive cells were observed in groups IV, V and VIII. RT-PCR revealed that a 484-bp strip can be found in groups IV and VIII, but unavailable in other groups. We conclude that HRE is a promising regulator for h-VEGF(165) gene expression following the changes of oxygen environment. HRE can induce the expression of h-VEGF(165) gene after hypoxia, but in normal oxygen condition, the expression of h-VEGF(165) was inhibited. Although expression of h-VEGF(165) mRNA ceased in normal oxygen condition under the control of HRE, expression of h-VEGF(165) protein was hysteretic to h-VEGF(165) mRNA expression.

Alteration of plasma trace elements in patients undergoing open heart surgery.

Trace elements may contribute to myocardial dysfunction and susceptibility of the phospholipid cell membrane to free-radical damage and oxidative changes. We studied the concentration of trace elements copper, zinc, and magnesium in cardiac surgery. Fifty-four consecutive patients for elective coronary artery bypass grafting (n = 30) and valve replacement (n = 24) were studied. Blood samples were collected every 30 min (T1-T5) during cardiopulmonary bypass and postoperatively (T6-T9). Plasma concentrations of copper, zinc, and magnesium were measured with flame atomic absorption spectrophotometry. The concentrations of copper, zinc, and magnesium were significantly different during and after cardiopulmonary bypass (p < 0.01). The zinc concentration at T7 and T8 (p < 0.01) and the copper concentration at T1, T9 (p < 0.05) were significantly different between two groups. However, the magnesium concentration had no significant differences between the two groups (p > 0.05). In patients undergoing valve replacement or coronary artery bypass grafting, the concentrations of copper and zinc decreased significantly during cardiopulmonary bypass. Our study suggests that the current cardiopulmonary bypass protocol is adequate in the maintenance of c magnesium. However, the low copper and zinc concentrations found in the present study may suggest that in the future, supplementation particularly of copper and zinc may become a necessary procedure in cardiac surgery with cardiopulmonary bypass.

Relation between zinc, copper, and magnesium concentrations following cardiopulmonary bypass and postoperative atrial fibrillation in patients undergoing coronary artery bypass grafting.

Atrial fibrillation is the most frequently encountered arrhythmia following cardiac surgery. Since the essential trace elements zinc, copper, and magnesium are suspected to have an effect on postoperative atrial fibrillation, the concentrations of these elements were determined by flame atomic absorption spectrophotometry in the plasma of 60 patients undergoing elective coronary artery bypass grafting. Blood samples were collected every 30 min during cardiopulmonary bypass and postoperatively. Plasma concentrations of copper, zinc, and magnesium were measured with flame atomic absorption spectrophotometry. All patients were monitored by continuous electrocardiography until they became outpatients or immediately after atrial fibrillation had taken place. Atrial fibrillation occurred in 13 of the 60 patients, corresponding to 21.7%. The zinc and copper concentrations at postoperative days 1 and 3 were significantly different (P < 0.05) between patients with and without atrial fibrillation. The concentrations of zinc following cardiopulmonary bypass recovered more slowly in patients with postoperative atrial fibrillation than in patients without it. Whether or not supplemental zinc could lower the incidence of postoperative atrial fibrillation should be evaluated in future prospective randomized clinical trials.