Peripheral Vascular Disease

Deep Vein Thrombosis (DVT) & Travel

Abdominal Aortic Anuerysm (AAA)

Carotid Artery Disease (CAD)

Hyperhydrosis

Carotid Artery Disease (CAD)

Anatomy
Carotid arteries take blood up to the front of each side of the brain. At the base of the brain they join in a network called the “Circle of Willis. They combine with the two vertebral arteries which supply the back of the brain. In many patients blockage of one artery can be taken over by another. At least a quarter of patients have an incomplete or fully developed Circle of Willis and this doesn’t occur.

Carotid Stenosis
Narrowing of the Carotid Arteries typically occurs in the middle of the neck where the arteries divide from the common Carotid Artery coming up from the chest into the Internal Carotid Artery which supplies the brain and the External Carotid Artery which supplies the face. Flow abnormalities at this point seem to cause sheer stresses which cause internal intimal injuries. This is then progressive and causes build up of atheroma, fibrosis, cholesterol and even calcium. The intima can be disrupted leading to an ulcer inside the walls. In this ulcer platelets can develop.

TIA
Platelets or debris from the ulcer will be carried by the blood supply upwards and this may cause blindness in the eye on that side (amaurosis fugax)) or a stroke affecting that hemisphere which will then affect the arm or leg on the other side. Speech and comprehension can also be affected. Carotid Artery Disease is strongly associated with diabetes, smoking and coronary artery disease. Carotid Artery Disease is a common cause of stroke. Because there are no symptoms of claudication as there are in the legs, the Carotid Disease can be silent until a stroke occurs. It is easily suspected in the patient profile and easily investigated with the Carotid Ultrasound exam. Carotid narrowing is associated with a decreased life prognosis. In America that has been used for health screening. In Australia it would be more appropriate to treat the patients’ vascular risk factors.

Referrals & Management
Patients who have significant Carotid narrowing should be referred for a vascular surgical opinion. Generally patients with under 50% narrowing of the internal carotid artery as measured near it’s origin are treated medically. Those with a narrowing in the range of 50-70% may occasionally have surgery but I generally treat it medically but prepared for the possibility of surgery. Those with narrowings over 70-80% may well require surgery. CEA surgery is more indicated in those that have had symptoms of a temporary stroke or a mild stroke from which they have recovered. Occasionally asymptomatic lesions which are progressive in younger patients are appropriate to treat. In this patient group surgery is preferred because that is still the best proven intervention. Carotid Angioplasty and Stenting (CAS) is an alternative. The interested reader should look under procedures – Carotid Endarterectomy for further discussion of this topic.

Screening
With an aging population and an epidemic of arterial vascular disease in Australia Carotid Artery Disease should be suspected in many patients. It should be actively sought for by Carotid Ultrasound exam which is simple and inexpensive. A normal exam could probably be relied on for 3 to 5 years. An abnormal exam might be repeated in 12 months. A significantly abnormal exam should occasion vascular surgical referral.

Angiography/CTA
Carotid Angiography is rarely if ever used except in intervention these days. A newer alternative is CT Angiography which has significant limitations in calcified arteries and is often used to show the carotid arteries whereas it needs to show everything from the base of the heart to the intracerebral circulation as it is a processes image older CT scanners which produce reconstructions from two three or five millimetre slices or images are unhelpful. Newer scanners provide images on one millimetre or less slices. There are still significant limitations relating to patient movement and calcification in the arteries.

Magnetic Resonance Imaging
Magnetic Resonance scanning (MRI) avoids the dangers of X-Ray contrast and X-Ray exposure but generally overcalls the degree of Carotid stenosis or narrowing. It has a role in looking for intracerebral abnormalities, particularly clinically silent cerebral infarcts in the territory of a narrowed carotid artery. CT Scanning is poor at showing these but MRI using DW images quite often shows fresh cerebral infarcts. Clearly that may affect management of the case.

Overview
Carotid Artery disease management requires close and rigorous control of blood pressure usually with multiple agents. A lipid lowering drug is mandatory. An anti-platelet drug is added. Aspirin 75-100mg per day is the usual drug. Some patients may be put on Clopidogrel 75mg per day. Some patients may go on both. Combining them with other drugs has been tried but without much benefit. There are almost as many papers written on Carotid Disease and management plans suggested for Carotid Diseases as there are patients with the disease. In this blizzard of information it is difficult for patient’s to see which way they should proceed. Aggressive medical management, selective Carotid Endarterectomy and occasional Carotid Angioplasty and Stenting seems to have been the best balance of management for the last ten years and will probably apply for the next ten years at least.