Correction of erythrocyte shape abnormalities in familial hypercholesterolemia after LDL-apheresis: does it influence cerebral hemodynamics?

Altered vascular reactivity to circulating angiotensin II in familial hypercholesterolemia

ABSTRACT

We have previously shown increased vascular reactivity to angiotensin (Ang) II in familial combined hyperlipidemia. However, this has not been well studied in familial hypercholesterolemia (FH), a condition with incipient endothelial dysfunction. This study aimed to examine microvascular and macrovascular responses to Ang II in FH. Therefore, we investigated the effects of a 3h infusion of Ang II on blood pressure and forearm skin microvascular function in 16 otherwise healthy FH patients and matched healthy controls. Skin microvascular hyperaemia was studied by laser Doppler fluxmetry during local heating. Microvascular resistance was determined by the ratio mean arterial pressure/microvascular hyperaemia. Macrovascular reactivity was assessed by changes in brachial blood pressure. Compared to the controls, the FH group had increased baseline systolic blood pressure (127±14 vs 115±12 mmHg; P=0.02), while systolic blood pressure responses were similar (+24±9 vs +21±7 mmHg; P=0.26), after 3 h of Ang II infusion. At baseline, there were no group differences in microvascular hyperaemia or resistance. However, after 3 h of Ang II infusion, heat induced microvascular hyperaemia was less pronounced in FH (126±95 vs 184±102 arbitrary units; P=0.01), while microvascular resistance during heat induced hyperaemia was increased (1.9±0.9 vs 0.9±0.8, P=0.01), as compared to controls. Both these responses were further pronounced 1 h after stopping Ang II. In conclusion, despite similar blood pressure responses to Ang II in FH and controls, microvascular dilatation capacity was impaired in FH, indicating endothelial dysfunction. These findings and increased microvascular resistance may lead to hypertension and microvascular complications in FH.

Lipoprotein Apheresis

Patients with familial hypercholesterolemia (FH) have early development of atherosclerosis and cardiovascular disease (CVD). Lipid level-lowering medications are not always successful in reducing increased low-density lipoprotein C (LDL-C) levels. Lipoprotein apheresis (LA) therapy has proven its clinical benefit in reducing CVD events for patients with FH with hypercholesterolemia. LA reduces LDL-C levels by more than 60% in patients with FH and reduces CVD events. LA also reduces Lp(a) levels and CVD events. LA reduces inflammatory markers and blood viscosity.

Doppler study of cerebral arteries in hypercholesterolemia

Background:

Hypercholesterolemia is one of the major modifiable risk factors for atherosclerosis of the coronary and carotid arteries. Although transcranial Doppler (TCD) studies of the cerebral arteries are indicative of decreased cerebral blood flow velocities in patients with hypercholesterolemia, the number of these studies has been limited. The aim of this study was to assess the hemodynamic status of the cerebral arteries in patients with hypercholesterolemia using TCD.

Methods:

In a case-control study, 60 individuals, including 30 hypercholesterolemic cases (low-density lipoprotein [LDL] > 160 mg/dL) and 30 healthy controls were enrolled. Other arterial risk factors, including diabetes mellitus, hypertension, smoking, and obesity (body mass index > 30), were evaluated and matched as well. TCD was used to assess the hemodynamics of the intracranial arteries as well as the internal carotid arteries. The mean blood flow velocity, pulsatility index, and resistance index were recorded in all the arteries.

Results:

The mean blood flow velocity, pulsatility index, and resistance index of the intracranial arteries and internal carotid arteries were not significantly different between the two groups (P > 0.05). However, those with higher levels of LDL (>180 mg/dL) showed significantly lower mean blood flow velocity and resistance index of the internal carotid arteries than the healthy controls. In addition, individuals with high-density lipoprotein (HDL) <35 mg/dL had significantly lower mean blood flow velocity in the internal carotid arteries.

Conclusion:

Hypercholesterolemia (LDL >160 mg/dL) does not seem to have a detrimental effect on the hemodynamic status of the intracranial arteries and internal carotid arteries. However, in cases of higher LDL (>180 mg/dL) and lower HDL, decreased TCD parameters in the internal carotid arteries, as a surrogate of the peripheral arteries, are prominent.

LDL-apheresis therapy

Low-density lipoprotein (LDL)-apheresis is an effective means for acutely lowering plasma cholesterol (LDL reduction > 60%) and reducing cardiovascular events in patients with uncontrolled hypercholesterolemia who are genetically predisposed or resistant to standard therapy. Despite its known benefit, apheresis is performed in only a minority of qualified patients. In addition to reducing plasma cholesterol, apheresis can alter other markers of vascular disease (inflammation, rheology, thrombosis, and fibrinolysis). The acute and chronic changes to the vascular system may warrant LDL-apheresis use in other diseases.