Glossary terms - H

Haematoma

A blood clot that has formed outside a blood vessel (artery or vein).

Haemorrhage

The escape of blood from a ruptured blood vessel, externally or internally.

Haemorrhagic infarct

An area of dead brain that has had bleeding in it.

Haemorrhagic stroke

A stroke caused by a burst blood vessel bleeding into the brain (intracerebral haemorrhage) or into the surrounding areas (subarachnoid haemorrhage).

HDL-C (High-Density Lipoprotein Cholesterol)

Also known as the "good" cholesterol: a compound consisting of a lipid and a protein that carries cholesterol in the blood and deposits it in the liver.

Hemianopia

Loss of one-half of the normal field of vision. Homonymous hemianopia is the loss of the same half (either left or right) of the visual field in both eyes.

Hemiparesis

Weakness of one-half of the body.

Hemiplegia

Complete paralysis of half of the body.

Heparin

An anticoagulant drug given to prevent blood clots forming.

Homocysteine

An amino acid, which is an intermediate product in the biosynthesis of protein.

Hughes Syndrome

(also known as Primary Antiphospholipid Syndrome). Sometimes called 'sticky blood syndrome', because people with it have an increased tendency to form clots in blood vessels. Other symptoms include migraine, DVT, recurrent miscarriages, movement disorder, spinal cord lesions, organ thrombosis including heart, brain, kidney, liver and lung. ). One in five cases of stroke in people under 45 is associated with this condition, which can usually be treated once diagnosed.

Hydrocephalus

Raised pressure within the skull due to an abnormal build-up of the fluid that surrounds the brain. It can occur after a brain haemorrhage. May be treated by the surgical placement of a shunt system.

Hydrogenated fat

Hydrogenated fat is found in hard and semi-soft margarine and in vegetable shortenings. These products are often found in processed foods. They increase total and LDL (bad) cholesterol levels, which increases fatty buildup in arteries and raises the risk of stroke.

Hypercholesterolaemia

A high level of cholesterol in the blood.

Hyperglycaemia

High level of glucose in the blood and generally only seen in people with type 1 diabetes (also known as insulin dependent diabetes).

Hyperlipidaemia

A high level of fats in the blood.

Hypertension

High blood pressure, ie consistently more than 140/90mmHg.

Hypotension

Low blood pressure, ie consistently less than 90/60mmHg.