INTRODUCTION: Dissection of the ascending aorta is a relatively uncommon event and can be catastrophic. Fistulization between the aorta and pulmonary artery (PA) is an even rarer phenomenon and, unless recognized early, is fatal.
CASE PRESENTATION: An 84-year-old African-American female with a history of hypertension and coronary artery disease presented with sudden onset, sharp, retrosternal pain. The patient was witnessed to suddenly stand up, grab her chest, and complain of pain. She was diaphoretic, nauseous, with one episode of non-bloody emesis. On arrival to the hospital, significant vitals were a blood pressure of 83/50 and oxygen saturation of 92% breathing room air. She was treated with oxygen, sublingual nitroglycerin, and one liter of crystalloid with improvement in her symptoms. Initial labs showed a troponin of 0.02ng/dL, a compensated metabolic acidosis with a widened anion gap, and a lactate of 9.8mmol/L. Chest x-ray (CXR) showed stable cardiomegaly and pulmonary vascular congestion. EKG did not show significant change from baseline. Patient was admitted to the medical intensive care unit (MICU) with a diagnosis of unstable angina and volume depletion. On arrival to the MICU, the patient became hypotensive and briefly apneic. A new CXR showed a right upper lobe opacity with rightward tracheal deviation, blunting of the right costophrenic angle (CPA) and thickening of the lateral right pleura. The cardiac silhouette was markedly enlarged. A computed tomography (CT) scan with contrast showed a lobulated posteromedial aortic root with a mural irregularity communicating with the right PA which showed a discontinuity of the arterial luminal contrast column representing further dissection into the right lower lobe PA branches. A moderate pericardial and right greater than left pleural effusion was present and thought to represent hemorrhage. The diagnosis of an acute ascending aortic dissection with fistulization into the right PA was made. The patient’s family was made aware of this and given the option of surgical correction but decided to treat the patient with comfort measures and not to resuscitate/intubate. She passed away shortly thereafter.
DISCUSSIONS: Aortic dissection is an uncommon and often catastrophic process. The incidence of an acute aortic dissection ranges from 2.6 to 3.5/100,000 person-years.1 The complication of a thoracic aortic aneurysm (TAA) dissecting and rupturing into the PA is rare and is caused by an intimal tear that proceeds antegrade and ruptures through the adventitia leading to a fistula. A review of 4,000 autopsies of TAA's revealed that only 3.7% of ruptured aneurysms do so into the pulmonary artery.2 The most common cause is atherosclerosis, however other etiologies such as Marfan's syndrome, trauma, and aortitis need to be considered as well. In addition to communicating with the PA, aortic dissections have been known to fistulize into the right atrium/ventricle and left atrium as well as the superior vena cava.
CONCLUSION: Aortic dissections with fistulization into surrounding structures were thought to be universally fatal, but several reports of successful surgical repair exist. The rate-limiting step is diagnosis. Patients suffering from an acute event can die quickly, and early imaging is paramount. Two-dimensional echocardiography with Doppler has been used both to diagnose dissections and to evaluate for abnormal flow between compartments. Other modalities, such as CT and magnetic resonance imaging may be required to evaluate the entire aorta as well as define the fistula more clearly in anticipation of surgery.
DISCLOSURE: Adam Wellikoff, No Financial Disclosure Information; No Product/Research Disclosure Information