Microvascular dysfunction in malignant hypertension; evaluation of the endothelial glycocalyx.

Patients with a hypertensive crisis are at high risk of developing accelerated
target organ damage, but the mechanisms by which these extreme blood pressure
elevations are translated into acute vascular target organ injury have not been
defined. We previously showed that cerebral autoregulation is impaired in
patients with severe hypertension and retinal lesions (i.e. malignant
hypertension). It remains unclear however whether reductions in cerebral blood
flow are also associated with decreased delivery of oxygen to the
cerebrovascular bed and whether this is different for patients having malignant
hypertension and patients with severe hypertension who lack retinal
abnormalities. In the present study we will examine differences in
microcirculatory glycocalyx in the tongue and oxygen content of the
cerebrovascular bed between patients with malignant hypertension and patients
with severe hypertension.

In the current study we want to evaluate the microcirculatory glyccalyx in
patients presenting with malignant hypertension and relate this to patients
with severe hypertension. Microcirculation is assessed using SDF imaging,
oxygen supply using NIRS and autoregulation of bloodflow by TCD. Long term
changes in the microvasculature and endothelial activation are assessed at the
outpatient clinic, after a week and after three months.

All patients admitted to the ER with a diastolic blood pressure >120 mmHg will
be transferred to the Medium Care Unit were they will be treated according to
protocol. Before starting infusion of parenteral medication the
microcirculation of the tongue will be assessed by SDF imaging, and additional
blood (40 ml) will be drawn. After transport to the Medium Care Unit (MCU) for
appropriate care, the intravenous infusion of labetolol is started (normal
protocol). According to protocol bloodpressure will be lowered with 25% and
after 1-, 2- and 4 hours SDF imaging will be performed and blood will be drawn
(total max 160ml). Patients are asked to visit the outpatient clinic within a
week and after 3 months for standard follow up. During these visits we will
evaluate end-organ damage and draw blood for *followup* measurements.

Since patients are being teated according to national guidelines and besides
extra blooddrwaings are subject to non-invasive measurements, the risk of
participation is low. The delay of treatment (<1hr) is within the time-limit
set in National guidelines (NIV richtlijn april 2003).