INTRODUCTION: Shock from the right ventricular outflow tract (RVOT) obstruction is rare. We report a patient who presented with intractable shock attributable to Saphenous Vein Graft (SVG) aneurysm eroding into the pulmonary artery trunk.
CASE PRESENTATION: A 67 year-old male presented with recurrent chest pain. He had a history of Coronary Artery Bypass Grafting (CABG) nine years prior. He underwent cardiac catheterization which revealed a large gradient between right ventricular (RV) and pulmonary artery (PA) systolic pressures, an aneurysmal SVG, and normal left ventricular function. Transesophageal Echocardiogram (TEE) showed marked dilation of the right atrium and ventricle, and reduced RV systolic function. The pulmonic valve was not well visualized. The patient left the hospital against medical advice, and shortly thereafter was found unresponsive in the hospital parking garage. In the emergency room he was hypotensive with blood pressure of 80/40, pulse 70, and pulse oximetry showed 80% on 100% non-rebreather. The patient was intubated. EKG showed an old right bundle branch block. The patient developed pulseless electrical activity (PEA). Cardiopulmonary resuscitation was performed successfully per ACLS protocol. Chest x-ray showed widened mediastinum (see figure 1). TEE was repeated and confirmed previous findings of RVOT obstruction with RV failure and absence of aortic dissection. Post-resuscitation patient's systolic blood pressure remained in 50s despite aggressive intravenous fluid boluses, high doses of multiple vasopressors and thrombolytic therapy with Tissue Plasminogen Activator. The patient continued to have intermittent PEA. He died two hours later. Autopsy showed a large SVG aneurysm eroding into the proximal pulmonary artery causing near complete RVOT obstruction (see figure 2).
DISCUSSIONS: Aneurysm of the SVG is a rare complication of CABG. Pseudo aneurysm involves one or more layers of the vessel and usually develops immediately after surgery due to technical complications of the procedure or infection. True aneurysm develops usually five years or more after surgery, likely due to progressive atherosclerosis secondary to exposure of the vein graft to arterial system pressures. These aneurysms are usually asymptomatic but can cause symptoms because of thrombosis, rupture, compression, and fistula formation into adjacent structures. Accordingly, it can present with unstable angina, myocardial infarction, heart failure, superior vena cava syndrome, cough, hemoptysis, hemothorax, cardiac tamponade, arrhythmia and right heart failure from left-to-right shunt due to fistula formation between aneurysm and pulmonary artery. To our knowledge this is the first report of SVG aneurysm eroding into the proximal pulmonary artery trunk causing RVOT obstruction and presenting as intractable shock. Diagnosis is usually suspected when a patient with prior CABG has a chest x-ray showing anterior mediastinal mass. Echocardiogram, CT, and MRA not only help in the diagnosis, but can further delineate the relationship of the aneurysm to surrounding structures. Coronary angiography is the gold standard for the diagnosis. Treatment options include medical therapy with surveillance, coil embolization, covered stenting, surgical resection, and excision of the graft with surgical revascularization. Surgical treatment is generally recommended for symptomatic patients. SVG aneurysm can cause sudden cardiovascular compromise due to cardiac tamponade or by eroding into the pulmonary artery as in our patient. Early recognition may help to prevent this potentially correctable but lethal complication.
CONCLUSION: In a patient with SVG aneurysm, intractable shock could be from RVOT obstruction from aneurysmal erosion into pulmonary artery trunk.
DISCLOSURE: Saurabh Chandra, No Financial Disclosure Information; No Product/Research Disclosure Information