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18004

Clinical and Echocardiographic Predictors of Alveolar Capillary Dysplasia (ACD): A Case-Control Study

Friday, October 19, 2012
Room R02-R05 (Morial Convention Center)
Roxanne Arcinue, MD1, Theodora Stavroudis1, Shahab Noori1, Shazia Bhombal2, Jacqueline Szmuszkovicz2, Mandeep Jassal3, Cynthia Herrington4 and Philippe Friedlich1, (1)Center for Fetal and Neonatal Medicine, Division of Neonatal Medicine, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, (2)Pediatric Cardiology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, (3)Pediatric Pulmonology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, (4)Cardiothoracic Surgery, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA

Introduction:  Alveolar capillary dysplasia (ACD) is a rare, irreversible lung disease characterized by pulmonary hypertension and refractory hypoxemia, unresponsive to maximal cardiorespiratory support. Clinical and echocardiographic predictors for ACD, however, are still poorly understood.  Thus, ultimately, histopathology of lung tissue demonstrating the misalignment of pulmonary veins remains the gold standard for diagnosis.

Purpose:   The objective of the study is to compare clinical and echocardiographic measures of pulmonary hypertension and refractory hypoxemia in patients with ACD and matched controls. 

Hypothesis:  Patients with ACD have specific echocardiographic variables consistent with significant right-sided cardiac pressure elevations in the first postnatal weeks of life, unique from other causes of reversible pulmonary hypertension.

Methods:   A retrospective matched 1:2 case-control study at a quaternary neonatal intensive care unit from 2000 to 2011 was conducted. ACD patients were compared to patients with meconium aspiration syndrome and/or sepsis matched by birth year, gestational age, birthweight, and NICU admission date. All patients were on ECMO and inhaled nitric oxide. Demographics, onset of illness, presence of congenital anomalies, respiratory, and echocardiographic variables were analyzed and compared between the cases and controls.

Results:   Five patients were identified with ACD by histopathology and matched to 10 controls. Demographics, onset of illness, and oxygenation indices were not statistically significant between the groups. Compared to controls, ACD cases had more cardiac (40% vs. 0%, p = 0.03) and gastrointestinal (40% vs. 0%, p = 0.03) congenital anomalies; higher pH (7.42 ± 0.1 vs. 7.27 ± 0.2, p = 0.04); and a trend toward lower mean airway pressure (14.5 ± 2.5 vs. 17.7 ± 3.5 cm H2O, p = 0.07) on admission. In the first five echocardiograms obtained, 100% of ACD cases had persistent right atrial enlargement (RAE) with right ventricular hypertrophy (RVH) compared to 20% of controls (p = 0.02). Tricuspid regurgitation velocities (TRV) were greater than 3.9 m/sec in 100% of cases and 67% of controls (p = 0.05) in at least two of the first five echocardiograms. Persistence of septal flattening/bowing on the 3rd to 5th echocardiograms were noted in 100% of ACD cases and 10% of controls (p < 0.001). All five cases expired; one out of 10 controls expired.

Conclusions:  ACD should be suspected when the first five serial echocardiograms show persistence of RAE with RVH, septal bowing/flattening, and TRV measurements higher than 3.9 m/sec despite optimal modulation of pulmonary vascular tone and ECMO support. We speculate that the ability to clinically identify variables associated with ACD in the first postnatal weeks may improve the clinical management of patients suspected to have ACD by early enlistment for lung transplant therefore prolonging survival, or on the other hand, offering palliative care earlier in the patient’s hospital course, thus, circumventing invasive and futile interventions