When to Operate on Pediatric Patients with Congenital Heart Disease and Pulmonary Hypertension

DOI: 10.5935/abc.20170134 In pediatric patients with congenital heart disease associated with pulmonary arterial hypertension (PAH-CHD), deciding about surgery may be difficult depending on the diagnostic scenario. Most patients with communications between the cardiac chambers or the great arteries can now be operated on quite safely, with excellent results. Pulmonary hypertension accounts for complications in less than 10% of cases. In general, it has been considered that early assignment to surgery is the best strategy to avoid complications. This is unquestionable. However, late referral is still a problem in developing countries and underserved areas. Furthermore, it must be acknowledged that severe pulmonary vasculopathy may be present early in life, leading to the speculation that vascular lesions may develop from birth, or even before. Moderate to severe pulmonary vascular abnormalities limit the success of the repair of cardiac anomalies. First, the so-called postoperative pulmonary hypertensive crises are relatively infrequent in the present era, but still associated with high mortality rates (>20%).1 Patient management requires sophisticated armamentarium for life support, sometimes extracorporeal membrane oxygenation (ECMO). Second, patients surviving the immediate postoperative period may remain at risk of persistent postoperative PAH, which is associated with poor outcome compared to other etiologies of pediatric PAH.2 Therefore, while becoming aware of these complications, clinicians and surgeons need to get together and plan the best therapeutic strategy on an individual basis. For a long time, cardiac catheterization (with the acute pulmonary vasodilation test, AVT) has been considered as a gold-standard assessment of PAH-CHD. In most tertiary centers indeed, catheterization data occupy a high hierarchical position in the decision to operate on PAH-CHD patients. Also, subclassifications of PAH-CHD according to disease severity are based on hemodynamic parameters. However, obtainment and interpretation of catheterization data are not easy tasks, especially in the pediatric population, for several reasons: 1the procedure is generally performed under general anesthesia, mechanical ventilation and muscle relaxation, therefore, far from the physiological conditions; 2even mild systemic hypotension (for example, due to inadequate hydration in regard to the effects of anesthetic drugs) makes results impossible to analyze in subjects with systemic-to-pulmonary shunts; 3direct measurement of oxygen consumption, which is essential for calculations of pulmonary and systemic blood flow, is not done in many institutions; 4inhaled nitric oxide is expensive and, therefore, unavailable in many centers, limiting the performance of the AVT; it is widely known that challenging the pulmonary circulation with ~100% oxygen is not adequate to test for vasoreactivity, leading to inaccurate results; and 5there has been no consensus about the protocol for the AVT in the pediatric population, and the magnitude of the response does not correlate with outcomes in CHD.3 In view of all these difficulties, cardiac catheterization remains as an important step in the evaluation of PAH-CHD,4 but data are now taken into consideration as part of the whole diagnostic scenario.