Peripheral Arterial Disease
Peripheral arterial diseaseis also known as atherosclerosis or hardening of arteries. It is a chronic disease in which plaque builds up gradually in the arteries to the legs. Plaque is made of excessive fat, cholesterol, proteins, calcium and other substances in the bloodstream. The build-up of plaque on the wall of artery will progressively narrow down the lumen to complete blockage of the artery resulting damage to the soft tissues and eventually tissue death (gangrene).
Peripheral arterial disease is more common in people who are 65 or older, but can occur at nearly any age. Smoking, high blood pressure, high cholesterol or triglycerides, diabetes, kidney failure and obesity will increase your risk of peripheral arterial disease.
The diagnosis is made based on history and physical examination, usually followed by a duplex ultrasound scan. If more detailed information is needed or if intervention is being planned, a CT or MR angiograms may be required.
PVD is largely a clinical diagnosis aided by tests. At our clinic, all patients suspected of having PVD will undergo comprehensive screening with a full history of possible risk factors and symptoms. A thorough physical examination will also follow. This includes examination of the pulses in the foot to detect abnormal pulses. Blood tests are also required to screen for high cholesterol, kidney function as well a diabetic control. Other investigations include:
- Arterial and Venous Duplex Ultrasound Scans
- CT Angiograms
- MR Angiograms
- Minimally invasive Diagnostic Angiograms
- Ankle Brachial Pressure and Toe Pressure Indices
- Transcutaneous Oxygen Measurement (TCOM)
A duplex ultrasound is a non-invasive method of detecting and quantifying the narrowing and blockage in the blood vessels. It is performed by a trained sonographer and is verified by a Radiologist. It is a painless procedure performed on a couch and usually takes 1-2 hours.
A CT Angiogram (Computer Tomography Angiogram) is a CT scan dedicated to look at the arteries of the body. After administration of intravenous dye (contrast), a scan lasting ~10-15 minutes will be obtained. This involves exposure to X-ray. A reconstructed image like the following can be obtained.
A MRA is similar to a CT scan except that it is time consuming but may give better resolution of images of the vessels in certain cases. It can be done with or without dye administration.
A diagnostic angiogram is the Gold Standard in diagnosing narrowing and blockages in the arteries. It involves cannulating the artery commonly in the groin followed by administration of dye (contrast)to visualize the whole arterial tree.
These are non-invasive methods of determining the degree of arterial perfusion in the feet and toes. The ankle-brachial index (ABI) is the ratio of the blood pressure measured at the ankle to the blood pressure measured in the upper arm. A low ankle-brachial index number suggests that the arteries in the legs may be narrowed or blocked.
The Toe-brachial index (TBI) is the ratio of the blood pressure measured in the big toe to the blood pressure measured in the upper arm. This index is more commonly used in patients with diabetes as calcification of foot arteries is more prevalent in people with diabetes. The calcified arteries in the ankle are likely to be in compressible, resulting in inaccurate ABI. On the other hand, calcification occurs less commonly in digital arteries of diabetes, this makes TBI more reliable and predictive of arterial disease.
This is a painless non-invasive test used to measure the oxygen level of the tissue below the skin. This test is especially useful in patient with wound(s) in the foot, as the TCOM value is predictive of tissue perfusion and wound’s healing capacity.
For patients who have severe is chaemia from peripheral arterial disease, especially with associated wounds in the foot, attempts to improve blood supply in the leg are indicated. The goals of improving blood supply to the leg are to reduce pain, improve functional capacity and quality of life.
In current practice, both minimally invasive treatments (such as angioplasty or stenting) and traditional procedures such as bypass surgery have important roles in preventing lower limb amputation.
Bypass surgery is a well-established and highly effective procedure for patients with blocked arteries in the legs. This is an open surgery to re-route blood by using patient’s vein or prosthetic graft to bypass the blockage and restore direct flow to the lower leg and foot.
Angioplasty is a minimally invasive or ‘keyhole’ procedure for patients with peripheral arterial disease. The procedure is carried out via a small cut in the groin, followed by insertion of a plastic tube (Sheath) into the artery guided by ultrasound or X-ray. Through the plastic tube, the blocked or narrowed artery is stretched open using a specialised balloon. Occasionally a stent may need to be placed across the blocked or narrowed artery in order to maintain the luminal size. This procedure can be done under local anaesthetic, sedation or general anaesthesia.
Hybrid vascular procedure combines the benefits of both Open Surgery and Endovascular Intervention in the management of vascular disease. It is performed simultaneously in a hybrid operating room in one setting. The hybrid operating room is an operating theatre that is equipped with advanced medical imaging which allows the combination of open surgeryand endovascular intervention to carry out simultaneously in a patient.
Remote Endarterectomy is a common hybrid procedure that combines open surgery and endovascular techniques. Through a medium sized incision in the groin, the plaque in the artery of the thigh is cored out.