CA-42
Anesthetic management of Tetralogy of Fallot with major aortopulmonary collateral arteries (MAPCAs)
1Quinonez Z, 2Downey L, 3kuan C, 3Wise-Faberowski L
1Texas Children's Hospital, Houston, TX, USA; 2Emory University, Atlanta, GA, USA; 3Stanford University/Lucile Packard Children's Hospital, Palo Alto, CA, USA
Background:
Tetralogy of Fallot with major aortopulmonary collaterals (MAPCAs) is a heterogenous disease with varying degrees of severity, requiring complex anesthetic management. Our institution has adopted the approach of early complete repair with incorporation of all lung segments, extensive lobar and branch segmental pulmonary artery reconstruction and VSD closure. The median age of our patients is 8.6 months (4.9-29). The median number of MAPCAs unifocalized is 3 (2-5) with overall survival after repair 92.5% due to a multidisciplinary approach.
Pre-operative:
Most critical to the anesthetic assessment is an estimate of overall pulmonary blood flow. Patients are categorized as having high, low or balanced pulmonary blood flow based on systemic oxygen saturation (>90, <75% or 75-90%). Anesthetic management for patients with unbalanced pulmonary blood flow is challenging. Underlying genetic syndromes, Alagilles and 22q11 (2.8% and 36%),pose additional anesthetic risk.
Pre-bypass:
Approximately, 11% of our patients have a concern for abnormal airway anatomy and require a pre-repair bronchoscopy. Though previous surgical repairs were staged procedures, through lateral thoracotomy, our current approach is via median sternotomy, without need for single-lung ventilation. In order to minimize total bypass times and subsequent bleeding risk, the surgeon will perform much of the dissection and localization of MAPCAs, 262 (173-318) min, prior to the initiation of bypass.
Because of the prolonged nature of these repairs, reliable arterial and intravenous access is paramount (central venous catheter, radial and/or femoral arterial line and 2-3 large size pivs). It is not uncommon for these patients to become acidotic and hypoxic prior to going on bypass, requiring volume administration (blood),and sodium bicarbonate . Low dose dopamine can also help in tenuous hemodynamic states.
Post-bypass:
Establishing hemostasis and maintaining good oxygenation and ventilation can be tenuous. Most patients require the following inotropic support: dopamine (3-5 mcg/kg/min), milrinone 5 mcg/kg/min and epinephrine (0.01-0.05 mcg/kg/min). Post-bypass bleeding can be significant due to the amount of dissection, prolonged bypass times (median 252 min; 191-325), and the many suture lines for vascular re-anastomoses. After transfusion of cryoprecipitate and volume-reduced platelets, our institution has instituted the use of FEIBA (Shire US, Inc. IL; anti-inhibitor coagulant complex) at a dose of 10 units/kg (max 30 units/kg).
Based on retrospective analysis, in complete repairs (bilateral unifocalization with VSD closure) achieving a right ventricle; aortic pressure ratio, under or near 0.35 (0.32-0.4), is predictive of improved postoperative outcome. In our efforts to assist with lowering immediate post-operative right ventricular pressure, empiric intra-operative nitric oxide is instituted at 20 ppm.
Conclusion:
We have anesthetized over 500 patients at our institution, of which many (64%) have undergone a single-stage complete repair with VSD closure. Vigilance in anesthetic management is a key component to the outcomes of these patients in order to maintain a low perioperative mortality rate (1.7%).
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