Subarachnoid haemorrhage in a patient with undiagnosed aortic coarctation

Background

While intracranial aneurisms are present in 3%–5% of the population, fortunately only a small proportion rupture and create subarachnoid haemorrhage.1 The aetiology of intracranial aneurisms is not fully understood, but hypertension is a well-established independent risk factor.1

Aortic coarctation is a congenital narrowing of the aorta, typically situated just inferior to the subclavian arteries where the ductus arteriosus connects to aorta with a prevalence of around 4 per 10 000 live births.2

Severe coarctation and interrupted aortic arch are often diagnosed in neonatal life when the ductus arteriosus closes and postductal perfusion is compromised or if acute left heart failure develops. However, in some cases coarctation is discovered later in life during investigation of hypertension, cardiac murmur and/or large differences in systolic blood pressure in the upper and lower extremities generating a low ankle/brachial index (ABI). Echocardiography in the suprasternal window, MRI scan or CT angiography provides the final diagnosis. Untreated coarctation has a high mortality rate due to a dramatically increased risk of congestive heart failure, aortic rupture, endocarditis and subarachnoid haemorrhage (SAH). The increased risk of SAH is presumably mediated by a high arterial pressure cranial to the stenosis leading to formation of intercranial aneurysms and subsequent rupture.3

Case presentation

A male construction worker in his mid-30s was admitted with hyperacute occipital headache during a heavy lift at work. He suffered from obesity, sleep apnoea, asthma and attention-deficit disorder, which was treated with methylphenidate. He had a history of dysregulated hypertension, with measurements around 160/100 mm Hg. In the emergency department his blood pressure was 260/100 mm Hg, his heart rate was 80 beats per minute and he was sweating. Otherwise, he was without symptoms or neurological deficits.

Investigations

A decade earlier, the patient was admitted with dysphasia and hypertension. At that time, he also had a periodically drug abuse. Brain imaging showed a subcortical lesion in the left frontal lobe suggested to be secondary to demyelination or hypertensive encephalopathy. Other neurological assessments, including brain MRI and lumbar puncture, were normal. The cause of the subcortical lesion was never confirmed. As the dysphasia resolved spontaneously, he was transferred to the cardiological department, where he underwent extensive workup to determine the cause of hypertension. Echocardiography, renography, blood samples and urine catecholamines were normal ruling out cardiomyopathy, renal disease, renal artery stenosis, hyperthyroidism, Cushing’s disease, hyperaldosteronism and pheochromocytoma. Examination of pedal pulse was not mentioned in the medical chart. The elevated blood pressure was interpreted as essential hypertension and the patient was discharged to ambulatory antihypertensive care. However, normotension was never achieved.

In the current admission, due to presence of thunderclap headache and high blood pressures, SAH was suspected. Brain imaging confirmed the diagnosis (figure 1) and the underlying cause, a ruptured aneurysm of the right pericallosal artery (figure 2A).

Treatment

The patient was planned for endovascular occlusion (coiling) in general anaesthesia. Induction was performed with propofol and remifentanil, rocuronium for neuromuscular blockade and norepinephrine for a target mean arterial blood pressure of 80–100 mm Hg monitored with a radial arterial line. Through the right femoral artery, a 6F sheath was placed in the descending aorta. Through this a 5F diagnostic catheter was advanced towards the carotid arteries, but it was difficult to pass the aortic arch. The radiologist (TS) suspected a severe aortic stenosis. However, she managed to get the catheter through a loop into the ascending aorta and inject contrast. The carotid arteries were voluminous and there was a pronounced collateral flow (figure 2B). The endovascular procedure was discontinued due to compromised manoeuvrability across the stenotic area. Before femoral sheath removal, an invasive pressure was measured in the descending aorta revealing a 100 mm Hg systolic pressure drop across the distal aortic arch (figure 3) and an ABI of 0.46. The procedure was converted to surgical clipping and the aneurism was successfully closed. Postoperatively, the patient was admitted to the intensive care unit and a thoracoabdominal angiography was performed, which confirmed the diagnosis of aortic coarctation (figure 2C,D). Clinically, pulses in feet and inguinal areas were weak bilaterally and the ABI was 0.65 (normal range 0.9–1.2). A new echocardiography was performed and the stenosis was visualised in the suprasternal view, which had not been performed on earlier examinations. The patient had presumably developed severe hypertension secondary to low kidney artery pressure (as previously described in patients with aortic coarctation) leading to both left ventricular hypertrophy and likely aneurismal formation and rupture.1 He was transferred to the neurological ward in good condition without further complications.

With the current clinical presentation, aortic coarctation was quickly suspected. However, aortic coarctation is usually diagnosed in the first few days after birth when the ductus arteriosus closes, or in general practise where ABI can give a clue of the diagnosis. Also, contemporary standards for echocardiography include a suprasternal view, but that can be challenging, particularly in obese patients, which may explain why it was not performed earlier.

Outcome and follow-up

In the subacute phase, vascular surgery with dilatation and stenting of the coarctation was planned. The coarctation had a diameter of 4 mm at the coarctation site compared with 18 mm in the transverse aortic arch. Multiple arterial collaterals were confirmed, which is normal in aortic coarctation. Uncommonly, a poststenotic aortic aneurysm with a maximal diameter of 37 mm was discovered where the so-called duct ampulla is sometimes present in early life. After ruling out mycotic aneurysm with a positron emission tomography (PET)-CT scan, it was concluded that the aneurysm was most likely stable and did not require intervention. Vascular intervention with direct stenting was performed using a 39 mm covered CP stent (NuMed, Sheffield, UK) mounted on 18 mm balloon-in-balloon (BiB) (NuMed) balloon, subsequently telescopically prolonged with a second 39 mm covered CP stent mounted on a 20 mm BiB. A new pressure measurement showed a peak-to-peak gradient <10 mm Hg and an ABI of 0.95. Aortography showed no signs of aortic rupture or other complications. The timeline is outlined in figure 4.