Near‐occlusive ductal thrombus extending to abdominal aorta in neonate: Recovery with thrombectomy

A term 8-day-old, 3.1-kg male presented with lactic acidosis, absent femoral pulses and a blood pressure of 132/90 mmHg in the right upper extremity. He had been delivered by forceps after an uneventful pregnancy. An empiric diagnosis of coarctation of the aorta (COA) or other duct-dependent, left-sided cardiac defect was made, and resuscitation included intravenous prostaglandin, crystalloid infusion, inotropes and intubation. Echocardiography demonstrated severe left ventricular (LV) dysfunction and mitral regurgitation but otherwise normal cardiac morphology. There was no flow in the patent ductus arteriosus (PDA) after prostaglandin initiation, with evidence of a thrombus in the ductal ampulla (Fig. 1a). The aortic arch was not clearly visualised by echocardiography. However, clinical suspicion of an obstruction was supported by imaging. Resuscitation led to partial stabilisation and a gradual resolution of the lactic acidosis. Urine output and renal biochemistry remained normal and there was no clinical or radiographic evidence of splanchnic injury. Systemic haemodynamics remained stable with normal central venous saturations. The arterial lactate level normalised within 24 h of initial presentation, but blood pressure remained elevated at 128/86 mmHg in the right arm with pulseless lower extremities. A repeat echocardiogram on the following day demonstrated mildly depressed LV function with no evidence of ductal patency or COA. An abdominal ultrasound with colour doppler was performed and revealed complete absence of prograde aortic flow and evidence of occlusive thrombus extending from the infrarenal aorta to the external iliac arteries bilaterally (Fig. 1b). Computed tomography confirmed this diagnosis (Fig. 2). The external calibre of the aorta was normal throughout its course, but an occlusive filling defect extended from the level of (and included the) renal arteries down to the common femoral arteries bilaterally. The left renal artery exhibited reduced perfusion and only a trace of contrast was visible in the right renal artery. Neither the internal nor external iliac arteries were patent. Instead, each common femoral artery was supplied by collateralisation from the inferior epigastric branches. The patient underwent surgical thrombectomy within 48 h of initial admission. The infrarenal aorta was exposed via laparotomy and vascular clamps were applied proximally and distally. A transverse aortotomy was performed, revealing a fresh luminal thrombus. Inflow was present but sluggish. Back-bleeding was absent when tested. Fogarty balloon catheters (4 Fr and 5 Fr) were passed proximally and distally and repeatedly passed with increasing balloon volumes. A large quantity of fresh thrombus was retrieved distally, and a 2 cm organised cast with platelet cap was retrieved proximally from the level of the renal arteries. At the end of the procedure, both inflow and back-bleeding were brisk. After closing the aorta, exit angiography was performed via a 6 Fr sheath inserted just upstream of the aortotomy. The entire abdominal aorta was now patent with acceptable run-off through the external iliac arteries and into both common femoral arteries. The celiac axis and superior mesenteric arteries were both well perfused, but both renal arteries had an appearance consistent with vasospasm (Fig. 3). The internal iliac arteries were not visualised. The patient was returned to the intensive care unit (ICU) on continuous intravenous heparin. The femoral and distal pulses were now appreciable both clinically and by bedside doppler. On the first postoperative day, doppler ultrasound demonstrated recurrent near-occlusive thrombus at the aortic bifurcation. The right common iliac artery was partially occluded and flow through the left was present but reduced. Clinical status remained unchanged with no end-organ dysfunction and palpable lower extremity pulses. Recurrent thrombectomy was not pursued and the patient was continued on unfractionated heparin alone. In the ICU, the patient developed seizures, which were controlled with phenobarbital. Further investigations including an MRI revealed a small right intraventricular thrombus without significant parenchymal extension. He was discharged 10 days post-thrombectomy when there was demonstration of stability on subcutaneous enoxaparin and maintenance phenobarbital. Doppler ultrasound of the abdominal aorta at 2-week follow-up showed an aortic thrombus of decreased size with patency of the renal and superior mesenteric arteries. This patient had no long-term sequelae at 6-month follow-up. He continued to be followed by paediatric cardiology, surgery and haematology. Report of this case has been approved by the Institutional Ethics Board of the University of Toronto. Consent for this case report was obtained by the patient's guardian at the time of data collection. Aortic thrombosis occurs more frequently in the neonatal period than any other age and incidence varies between 0.1 and 1.1 per 100 000 births.1, 2 Occurrence can be associated with long-term renal and cardiovascular disease, ischemic stroke and an all-cause mortality rate of 15%.3 Similarly, it can cause aortic occlusion and may be mistaken for COA or other congenital left outflow obstructions. To our knowledge, there have been very few other case reports of newborn surgical arterial thrombectomy.4, 5 Our patient presented with a clinical diagnosis of COA, evidence of significant LV dysfunction and a significant clinical upper to lower extremity pressure gradient that prompted further investigations. Imaging provided evidence that a thrombus in the PDA progressed into a thrombus of the abdominal aorta, causing near-complete occlusion. Aneurysms of the PDA can occur in up to 8% of PDA cases; however, their incidence remains low at a population level with few reported cases in the literature.6 To our knowledge, this is the first case report to document a sequela of a PDA thrombus in near occlusion of the abdominal aorta. Although there are many predisposing factors in cases of neonatal aortic thrombosis, most cases are associated with invasive arterial monitoring, including both cardiac and peripheral catheterisation.4 Other predisposing factors are prematurity, length of post-term hospital stay, asphyxia, maternal diabetes, sepsis, polycythemia, male gender and thrombophilia.7 The management of acute, symptomatic thromboses in large arteries in neonates remains controversial, with no clear guidance from reputable authorities.8 Generally accepted strategies include anticoagulation with heparin (for non-occlusive, unthreatening thromboses), thrombolytic therapy and/or surgical thrombectomy. While literature remains limited, surgical thrombectomy in neonates has been reported to be safe and effective at reducing occlusion and risk of end-organ, renal dysfunction and limb necrosis in previous case reports.4 In this case, heparin anticoagulation was completed before surgical thrombectomy, in accordance with the algorithm published by Dieffenbach and colleagues for a high-risk, symptomatic thrombus. Aggressive use of systemic thrombolysis and surgical thrombectomy remains controversial in treatment of aortic thrombosis. Here we present the case of a male neonate who was treated with heparin and surgical thrombectomy following high-risk symptomatic aortic thrombus that progressed from a thrombus in the ductus. The patient had positive immediate outcomes and without sequelae at 6-month follow-up. Further experimental and comparative research are needed to produce strong treatment guidelines for cases of aortic thrombosis.