Coronary Artery Thrombosis in a Neonate With Critical Aortic Stenosis

J INVASIVE CARDIOL 2019;31(5):E91-E92.

Key words: aortic stenosis, neonate, pediatric cardiology

A 5-day-old term baby (weight, 3.5 kg) was transferred by air to our unit due to critical aortic stenosis (AS). Echocardiography showed severe left ventricular (LV) function impairment with diffuse LV hypokinesia and ejection fraction of 13%. The left atrium was moderately enlarged. The AS peak gradient was 70 mm Hg due to cusp fusion between the right and left coronary cusps. The newborn was taken to the cath lab, where right femoral artery access was easily obtained followed by heparin bolus of 50 IU/kg. Angiography of the ascending aorta showed a dysplastic, doom-shaped aortic valve with a negative flow jet toward the right anterolateral aortic wall and right coronary artery (RCA) occlusion at its mid segment, with its peripheral part reconstituted by collateral vessels from the left coronary artery connecting with the posterior descending artery (Figures 1A and 2A). Due to low systolic blood pressure (45 mm Hg) despite inotropic support with dopamine infusion, it was decided to proceed immediately with valvuloplasty and deal with the coronary occlusion afterward. During routine pre-valvuloplasty testing with pacing at 180 bpm, the patient developed ventricular fibrillation and was successfully cardioverted. Aortic valve annulus measured 7 mm; hence, balloon valvuloplasty followed, using a 7 x 2 Tyshak mini balloon catheter (B. Braun) with rapid pacing at 150 bpm. Disappearance of the balloon waist was noted and final hemodynamic peak gradient measured 15 mm Hg with no aortic regurgitation as seen on the repeat aortic angiogram. Interestingly, the angiogram also showed completely restored RCA perfusion, but acute pruning of the distal coronary network, implying embolization of the thrombus distally (Figure 1B).

The patient was transferred to our PICU, where initial troponin levels measured 27 ng/mL, but soon after started decreasing to 17 ng/mL on day 2 and 5 ng/mL on day 3 post intervention. Echocardiographic wall-motion abnormalities at the basal and mid-inferior territory were noted on return to PICU, likely related with the peripheral thrombus embolization. These echocardiographic abnormalities resolved 24 hours later. The patient was treated with intravenous heparin for 3 days and was then converted to oral aspirin. She was discharged home in excellent condition a week later with normal ventricular function, fractional shortening of 33%, AS peak gradient of 25 mm Hg, and trivial aortic regurgitation. Thrombophilia screen was negative. She remains well at 6-month follow-up.

To our knowledge, this is the first report describing coronary artery occlusion in a pediatric patient with critical AS. The femoral arterial puncture was straightforward and heparin bolus was given straight away; hence, thrombus formation in situ at the groin or transfer of it through the catheter are extremely unlikely. Furthermore, the RCA thrombus was seen at the very beginning of the procedure during initial aortogram and was located at the mid RCA, with the distal segment being perfused via collaterals. We cannot be sure about the cause of the thrombus formation or its exact timing, but hypothesize that this was either in situ fresh thrombus due to low cardiac output or secondary to an atrial arrhythmia in the presence of severe LV diastolic dysfunction and may have happened during the flight. The thrombus moved distally, most likely during cardioversion, as seen on the second angiogram. We conclude that attention should be given to the coronary arteries in low-flow critical AS, particularly in neonates and infants whose stroke volume is extremely low.

From ¹the Department of Congenital Heart Disease, Mitera Children’s Hospital, Athens, Greece; and ²Department of Cardiac Anesthesia, Mitera Children’s Hospital, Athens, Greece.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

The authors report that patient consent was provided for publication of the images used herein.

Manuscript accepted November 5, 2018.

Address for correspondence: Dr Aphrodite Tzifa, MD(Res), FRCPCH, Consultant Paediatric Cardiologist, Director of Congenital Heart Disease Dpt, Mitera Children’s Hospital, Athens, Greece Erythrou Stavrou 6, 15123, Marousi, Athens, Greece. Email: atzifa@mitera.gr