dilated ascending aorta symptomsdilated proximal ascending aortamild ectasia of the ascending aortamildly dilated ascending aortaectatic ascending aortaenlarged ascending aortaectatic descending thoracic aortaascending aortic aneurysm definitionthoracic aorta atherosclerosisenlarged thoracic aortatortuous thoracic aortaascending aorta surgery