SEPTIC coronary embolism is a rare complication of endocarditis. Aortic valve (AV) vegetations have been described as a source of coronary embolism resulting in myocardial infarction. 1The use of diagnostic coronary angiography to localize the obstruction is often considered contraindicated, since the intervention might promote further embolic events. 2Alternatively, transesophageal echocardiography (TEE) can be used to assess proximal coronary blood flow, 3,4however its utility in the management of a patient with suspected septic coronary embolism has not been described previously.
We report a case of AV endocarditis following epidural steroid injection for treatment of lower back pain. The patient developed cardiogenic shock with electrocardiography and echocardiography indicating acute ischemia. Despite a suspected coronary embolism, angiography was not performed. The patient was taken to the operating room for emergency AV replacement (AVR) and possible coronary artery bypass grafting (CABG). However, CABG was abandoned, since precardiopulmonary-bypass TEE demonstrated laminar blood flow in the left sided coronary arteries and a resolution of regional wall motion abnormality after the AVR.
A 54-yr-old male was brought emergently to the operating room for AVR and CABG in the setting of endocarditis and cardiogenic shock due to suspected septic coronary embolism. His medical history was significant for chronic eczema and discogenic disease affecting the right fifth lumbar nerve route. He underwent an uneventful epidural injection with methyl-prednisone (120 mg) and lidocaine (30 mg) resulting in resolution of his back pain. Two days after the injection, he became febrile (39°C), however did not seek medical attention until 6 days later when presenting to the emergency room. Magnetic resonance imaging (MRI) of his lower back showed fluid collections in the paraspinal muscles posterior to the spinal column near the level of the epidural injection. He subsequently developed aphasia and right-sided hemiplegia. Computed tomography findings were consistent with an infarction in the distribution of the left middle-cerebral artery. Blood cultures grew Staphylococcus aureus repeatedly, and transthoracic echocardiography (TTE) and TEE revealed AV vegetations as well as severe aortic regurgitation. At that point, surgery was withheld due to the potential risk of intracranial hemorrhage. Five days after his admission, the patient became hemodynamicly unstable and required inotropic support. His electrocardiogram showed 2 mm ST-depression in leads V2–V6and TTE demonstrated left ventricular anterior and lateral wall hypokinesis. He was taken emergently to the operating room with a diagnosis of AV endocarditis and coronary embolus. Intraoperative TEE showed severe aortic regurgitation with destruction of the coronary cusp (fig. 1), and a fistula between the aortic root and right ventricular outflow tract (fig. 2). Two-dimensional TEE imaging of the proximal coronary arteries revealed an open lumen of the left main, left anterior descending and circumflex arteries. Color flow Doppler demonstrated laminar blood flow in these vessels, suggesting coronary artery patency (fig. 3). The patient underwent closure of the fistula using a pericardial patch and homograft AVR including reinsertion of the coronaries. After the patient was weaned from cardiopulmonary bypass, TEE demonstrated normal wall motion and electrocardiography showed normal ST-segments. Therefore, CABG was not performed. The patient was transferred to the intensive care unit were he remained hemodynamically stable while inotropic support was withdrawn within 24 h. A brain abscess, requiring drainage, complicated his postoperative course further. Cultures from the brain abscess as well as from the paraspinal fluid collection grew Staphylococcus aureus . Twenty-five days after his heart surgery, he was discharged to a rehabilitation facility with persistent aphasia and right-sided hemiplegia.
TEE is an established diagnostic technique in the management of patients with infective endocarditis. 5In this case, the combined TEE findings of coronary artery patency and restored wall motion strongly influenced the surgical decision to abandon CABG. The use of TEE to evaluate coronary arteries has been described previously. 3,4,6However, the intraoperative use of TEE to rule out coronary artery stenosis is not commonly necessary, since most patients undergo coronary angiography prior to surgery. In contrast, angiography was considered contraindicated in this patient due to the risk of embolization. 2Intraoperative TEE demonstrated nonturbulent flow in the proximal left coronary arteries suggesting coronary patency. Intraoperative echocardiography also showed severe aortic insufficiency with destruction of the left coronary cusp and revealed a previously undiagnosed aorta to right ventricular outflow tract fistula. Aortic insufficiency can decrease coronary reserve and thus account for acute ischemia even in the absence of coronary artery obstruction. 7The presence of an aorto-ventricular fistula could in addition compromise coronary artery perfusion. Alternatively, a septic embolus occluding the patient's proximal coronary circulation could have been lysed “naturally” during the time from onset of ischemia until the patient had surgery. TEE only allows visualization of the proximal coronary circulation. Therefore, a distal coronary obstruction could not be excluded via direct visualization or color flow Doppler. However, the regional wall-motion abnormality had resolved upon completion of the surgery.
The potential causes of this patient's bacteremia are multi-fold. The patient had a long-standing history of chronic eczema and scratching, possibly leading to intermittent episodes of bacteremia seeding his AV. In addition, retrospective review of preprocedure MRI scans raises the possibility of a discitis, which also may have been a source of bacterial seeding. The systemic immunosuppressive effects of the epidural steroids could have exacerbated either condition leading to fulminant endocarditis. However, the time course of events with an onset of fever 2 days after an epidural steroid injection raises the possibility that seeding of skin-borne staphylococcus into the musculature instigated the cascade of events leading to bacteremia and endocarditis. Two facts may weigh against this line of reasoning. First, the patient never developed an epidural infection, which would be expected if a needle became contaminated on penetrating the skin. Second, there were multiple paraspinal fluid collections demonstrated on the MRI performed after the procedure, not one focal area of infection.