Rheolytic Thrombectomy For Adult Intraventricular Haemorrhage

Intraventricular Haemorrhage Approximately 30% of cases of spontaneous intracranial haemorrhage or severe head injury are complicated by intraventricular haemorrhage (IVH). Typically, IVH results from extension of deep intracerebral haemorrhage (ICH) or aneurysmal subarachnoid haemorrhage (SAH), though a third of patients may have primary IVH confined solely the ventricular system. In the absence of a demonstrable angiographic abnormality IVH is usually associated with deranged coagulation or vascular risk factors such as hypertension, diabetes, and smoking.

Both experimental and clinical studies have clearly demonstrated the independent effect of the volume of haemorrhage on death and disability from IVH. In animals, injection of blood into the lateral ventricle exhibits a dose-dependent increase in the risk of fatality, and early thrombolysis of the simulated IVH reduces the severity of neurological deficit. In retrospective reports of intracerebral haemorrhage patient series concomitant IVH consistently emerges as a risk factor for greater mortality and poor functional outcome. Similarly, multivariate analyses of data from the STICH and FAST prospective randomised controlled trials of ICH management has provided conclusive evidence that the presence and volume of IVH is a significant independent risk factor for mortality and morbidity.

The principal effects of IVH are mediated by intracranial hypertension and induction of inflammation with oedema in the periventricular white matter and deep grey structures. Blood within the ventricles blocks CSF pathways resulting in a sequence of hydrocephalus, acute rise in intracranial pressure (ICP), reduced cerebral perfusion, with a risk of ischaemia, and potential brainstem herniation. Exposure of the ependymal lining to blood initiates inflammatory cascades and leucocyte infiltration into the adjacent brain, with ensuing tissue injury, localised oedema, and eventually generalised brain swelling. Late effects of IVH include scarring of the ventricles and obstruction of CSF absorption by blood breakdown products, typically resulting in chronic hydrocephalus necessitating permanent CSF diversion (shunting).

Current Management of Intraventricular Haemorrhage The rapid onset of deleterious effects after IVH supports the rationale of early intervention to relieve hydrocephalus and raised ICP, and to reduce blood load and the resulting inflammation and oedema. In most neurosurgical centres the prevailing treatment paradigm is insertion of a ventricular catheter and external drainage to divert CSF and reduce ICP, though this can be of limited efficacy with a large IVH as expansion and distortion of the ventricle by haematoma plays a greater role in exerting mechanical pressure than obstructed CSF. Ventricular catheters also frequently block with blood, necessitating repeated surgery for replacement. Furthermore, this mode of treatment does not address the inflammatory effects of the haematoma itself, which may persist for several days or weeks before complete reabsorption occurs. Infusions of urokinase or recombinant tissue plasminogen activator via an external drain to accelerate clot lysis have shown promise, however, the effect is not immediate and serial treatments are required, each with an attendant risk of infection and rebleeding. Several authors have described transcortical or endoscopic surgical clot evacuation but such approaches are technically demanding, have limited success in terms of the volume of haematoma removed, and are not practicable in the emergency situation.

Rheolytic Thrombectomy Rheolytic thrombectomy (RT) involves a double-lumen endovascular catheter that delivers multiple high-speed retrograde water jets to create a hydrodynamic recirculation vortex that traps and mechanically fragments adjacent thrombus, with the resulting debris evacuated via the continuous aspiration lumen. Safety studies have shown that the technique causes minimal denuding of vascular endothelium with no difference in the degree of vessel injury compared with traditional balloon thrombectomy. Clinically, RT has principally been applied to endovascular extraction of acute thrombus in coronary arteries and the results of large randomised controlled trials testify to a favourable safety profile. RT has also been used successfully to treat intracranial dural sinus thrombosis, acute internal carotid artery occlusion, and for recanalising blocked synthetic vascular grafts.