Evaluation of pulmonary vascular resistance and vasoreactivity testing with oxygen in children with congenital heart disease and pulmonary arterial hypertension
Anadolu Kardiyoloji Dergisi/The Anatolian Journal of Cardiology
Estimating pulmonary vascular resistance index (PVRI) is of critical importance in determining the type of cardiac surgery, the decision to perform heart transplantation, the choice between surgery and drug treatment or combined modalities, even though it is not the only criterion for judgment (1, 2). A positive pulmonary vasoreactivity test (PVT) is accepted as an indicator of low perioperative risk and good prognosis. An acute positive response to PVT is reported in only 40% of patients (3) .
... % of patients (3) . This test has been applied in many centers, following different protocols and different evaluation criteria. Most centers use nitric oxide (NO) or oxygen (O 2 ) inhalation, iloprost nebulization, or a combination thereof. A reduction by 20% of mean pulmonary artery pressure (PAPmean) or in the ratio of pulmonary resistance to systemic vascular resistance index (PVRI/SVRI) will define the patient as being a "responder" (4, 5). Reports on PVT performed with different drugs have been published recently (5-8). The aim of this study was to define the hemodynamic parameters of patients undergoing cardiac catheterization in our center for congenital heart disease and pulmonary arterial hypertension (PAH), characterize the efficacy of O 2 use in the PVT, and present the clinical findings in these patients with congenital intracardiac shunts. The present study was conducted on a cohort of 30 children diagnosed with PAH and congenital intracardiac shunts and placed under close surveillance at the pediatric cardiology department of the study center between October 2009 and November 2011 (Table 1) . As described previously the criteria used for PAH definition and patient selection were considered as mean pulmonary arterial pressure (PAPmean) of ≥25 mm Hg, pulmonary capillary wedge pressure (PCWP) of ≤15 mm Hg, and PVR index (PVRI) of > 3 WU/m 2 at rest (6). The PVRI was calculated conventionally as the ratio of the difference between PAP and left atrial pressure or the pulmonary capillary wedge pressure to mean pulmonary flow, and the values were expressed as units per square meter. These parameters were also obtained before and after pulmonary vasoreactivity testing using 100% O 2 by simple face mask for 10 min when a high PAPmean was suspected. The PVT was considered positive if PAPmean or the PVRI/SVRI ratio exhibited a reduction by more than 20% (7, 8). Patients were evaluated in two groups according to PVT results, responders and non-responders ( Table 2) . The median age, height, weight, body surface area (BSA) and heart rate of the recruited patients were respectively 20.0 months, 76.5 cm, 9.2 kg, 0.41 m 2 and 112.0 beats/min. No significant difference was found in systolic PAP (PAPsystolic), SVRI, systemic flow (Qs) before and after PVT (p>0.05). The values of the other parameters before and after PVT were significantly different, with p<0.05. Average diastolic pulmonary arterial pressure (PAPdiastolic), PAPmean and median PVRI, PVRI/SVRI showed a significant decrease following PVT. Pulmonary blood flow (Qp) and its ratio to systemic blood flow (Qp/Qs) underwent a significant increase. The fall by more than 20% of PVRI and PVRI/SVRI was especially significant with regard to their PVT positivity (Table 3) . No complication occurred in any patient during PVT testing with oxygen. No statistically significant difference in PVT-related measurements before and after the test was apparent within the non-responder patient group. All values in the responders, except Qs and SVRI (p=0.541 and p=0.984, respectively) were significantly different before and after the test (p≤0.05). All of the significantly different parameters except the Qp/Qs ratio in the responders showed a reduction after the test, whereas Qp/Qs was increased (p=0.019). While 11 of 13 nonresponders received medical treatment and the other two underwent full surgical correction, 14 of 17 responders were subjected to full surgical correction. Three patients of the recruited 30 patients were lost. Two of the deceased three patients had undergone surgery and one had had medical treat-