CASE PRESENTATION: 56 year-old female former smoker with moderate obstructive lung disease presented for second opinion after multiple hospital admissions for CP, DOE and recurrent bronchitis. Hyper-inflated left lung, right mediastinal shift, and absent right hilar shadow noted on chest x-ray (CXR). CT angiogram revealed hypoplastic right lung with right greater left centrilobular emphysema, right nodularity, ground glass, and abrupt cessation right pulmonary artery. Right and left heart catheterization revealed mean pulmonary pressure of 27, and large arterial fistula between the left circumflex coronary artery and several branches of the right pulmonary vasculature. CT coronaries showed proximal interruption of the right pulmonary artery with collateral vasculature recruited from SA nodal branch of the left circumflex, bronchial, internal mammary, intercostal, and phrenic arteries.