Application of basic scientific knowledge.
The practice for vascular surgery requires extensive knowledge of the basic science and, a through training in general surgical techniques. In addition, it is necessary to possess detailed specialised knowledge of the anatomy, physiology of arteries, veins and lymphatics and of the pathological processes which may affect them. The effects of vascular disease may be manifest by dysfunction of an organ or limb served by the affected vessel and the vascular surgeon needs to acquire and apply detailed understanding if these processes.
Understanding relevant pathologies
Arteries are blood vessels that carry blood away from the heart towards different organs or parts of the body. Veins are blood vessels that carry blood from different organs or parts of the body towards the heart.
They may have valves that ensure that blood flows only in one direction i.e. towards the heart.
Lymphatics carry tissue fluid and lymph from subcutaneous tissues, organs and different parts of the body to finally drain into the left internal jugular vein. Lymph nodes are structures present in the course of the lymphatics.
They act as filters and play a very important role acting as primary line of defense against infections from bacteria, viruses, fungi and parasites.
A large proportion of the vascular surgical workload is concerned with the diagnosis and treatment of degenerative arterial disease (atherosclerosis) that may be associated with high levels of cholesterol, smoking, hypertension, diabetes mellitus and family history of the disease.
Since this is a systemic process all the arteries in the body are affected to some extent with some being affected more than others.
This disease causes damage to the inner lining of the artery resulting in deposits of fat,
cholesterol and calcium which makes the arterial wall rough, and hard.
This may result in narrowing or occlusion of arteries resulting in circulatory insufficiency in the organ or limb supplied e.g. peripheral arterial disease with cramp like calf muscle pain
(intermittent claudication) on walking (leg angina), gangrene (leg attack), carotid artery disease with TIA (brain angina), stroke (brain attack), renal artery disease with renal hypertension or
other organ failure.
The rough surface of the inner arterial wall may induce clot formation (thrombosis) which results in either further narrowing and occlusion of
the artery or the clot may break off (embolus) traveling to a smaller sized distal artery where it gets trapped, partially or completely occluding the artery.
This disease may also cause a weakening of the arterial wall resulting in local or focal abnormal distension (aneurysm formation) of the arterial wall with risk of life threatening rupture of the thinned vessel wall.
The other arterial pathologies encountered include damage during trauma or surgery, inflammation as a result of smoking, auto-immune disease and congenital malformations presenting in child hood or at a later date.
The lymphatic disease usually results from inflammation or blockages of lymphatics from parasites, cancer cells, or surgical trauma.
Clinical diagnosis and investigations
Clinical diagnosis involves taking a meticulous, detailed history, physical examination and performing relevant investigations. All these three activities are then correlated to establish the presence and extent of disease, the amount of physiologic disturbance caused and the estimate the disability produced or likely to produce in each patient. It is only then that an informed recommendation and decision be made about future course of action.
History taking involves an inquiry about symptoms produced with an estimation of the disability caused, estimating and ruling out the involvement of other arteries and organs, checking for the presence of risk factors, and trying to identify other issues relevant to the disease process, its detection, and treatment.
Physical examination involves a general examination, measurement of blood pressure, assessment of involvement of other arteries, establishing the extent of circulatory compromise with disability produced and identifying issues important in choice of investigation and therapy.
Investigations selected involve those used to document presence of risk factors, establish anatomical involvement and assess the physiological disability. The investigations included non-invasive modalities which are easily performed with no risk and invasive investigations which involve a slightly higher risk.
Documentation of risk factors involves performing blood test to rule out anemia, coagulopathies, assess liver and renal function, check presence of raised cholesterol and triglycerides. A chest x-ray and ECG is also done to assess the heart and lungs prior to surgery.
Non-invasive investigations are performed in the vascular laboratory with sophisticated techniques and equipment to provide accurate information without the need for injections, exposure to harmful radiation or drugs. These include Doppler measured blood pressure in arteries in the extremities both at rest and after reproducible exercise, duplex ultrasound scanning of the affected arteries or veins, plethysmography tests, laser doppler, etc.
Invasive investigations involve performing angiography where a needle is used to puncture or access an artery or vein to be studied. A wire is passed through the needle which is then withdrawn. A plastic catheter is then passed over the wire and the tip is carefully positioned at the required site and the wire removed. A radio-opaque dye (contrast) is then injected and x-ray pictures taken to delineate the arterial lumen with its disease an obstructions. Highly sophisticated digital equipment is used to enhance the quality of the images and improve the accuracy of the data. CT scanning with or without contrast is also used to provide valuable data about the pathology. Nuclear scans where a radioactive dye is injected in the vein are also used to identify the extent of circulatory insufficiency produced with estimation of deterioration in function. MRI scans may also provide valuable information when contrast agents cannot be used because of allergy or poor renal function.
Once all the raw data is available, it is clinically correlated and put into perspective to identify the relevance of each finding in that particular individual. An effort is made to treat the individual and not the investigation. This process involves detailed informative discussions between the patient, family and the vascular surgeon.
Prevention of vascular disease
Prevention of vascular diseases usually involves major life style changes in diet and personal habits to minimise the risk factors and slow down the degenerative changes taking place.
In the case of arterial disease, it involves taking daily exercise in the form of brisk walking, controlling intake of calories, cholesterol and fat rich food products, cessation of smoking, taking care of pedal hygiene, monitoring and maintaining blood sugar levels at acceptable levels in diabetics.
In the case of venous disease, it involves major change in work habits to reduce periods of prolonged standing or leg dependency, use of compression bandages or stockings, sleeping with limbs elevated, etc.
In the case of lymphatic diseases, elevation of limbs and use of compression is of paramount importance.
Treatment of Vascular disease.
Treatment of vascular disease involves conservative measures, radiological intervention and open surgery depending on the manifestation of the disease and its severity.
Conservative measures involve reducing risk factors, controlling blood sugar levels, reduction of cholesterol and triglycerides, taking daily exercise and maintaining good personal hygiene. Wounds are treated with appropriate local dressings and systemic antibiotics if indicated.
Radiological interventions include performing percutaneous balloon angioplasty (a balloon is inflated inside the narrowed artery), atherectomy (removing the cholesterol plaque), using stents (cylindrical metal mesh which acts as a scaffolding) and thrombolysis (dissolving the existing clot).
Surgical intervention can involve removal of thrombus or embolus, performing endarterectomy (removal of the plaque with a layer of the diseased wall of the artery), patch angioplasty (a piece of vein or artificial material is used to increase the artery size) or a bypass (a tube is stitched to the artery above and below the narrowed or occluded diseased portion). using the patients own veins or artificial (prosthetic) materials like cloth (dacron) or plastic (PTFE) or a combination of vein and prosthetic material.
SPECIFICS OF VASCULAR SURGERY
Operations performed on arteries
Repair of arteries damaged by trauma or during surgery.
Endarterectomy and reconstruction of carotid and vertebral arteries.
Emergency or elective repair of abdominal aortic aneurysm by open surgery or endoluminal (from inside) technique.
Balloon angioplasty of iliac, femoral or popliteal arteries.
Thrombectomy or embolectomy (cleaning) of femoral or brachial artery.
Proximal bypass of diseased lower limb arteries like aorto-iliac or femoral, femoro-femoral crossover bypass, axillo-bifemoral bypass.
Distal bypass in lower limbs like femoro-popliteal (above knee or below knee), femoro-tibial or femoro-pedal bypass for limb salvage.
Reconstruction of arteries of the upper limb.
Renal or mesenteric artery reconstruction or bypass.
Temporal artery biopsy
Operations performed on veins
- Ligation, stripping & avulsion of varicose veins & perforators.
- Injection sclerotherapy of varicose veins & venous malformations.
- Venous thrombectomy and insertion of venous caval filters.
Operations performed on lymphatics
- Ligation of lymphatics.
- Lymphatic bypass.
Operations for vascular access
Providing access for hemodialysis (arterio-venous fistula or arterio-venous grafts) and peritoneal dialysis.
Providing venous access for long term chemotherapy, antibiotic therapy, regular long term requirement of transfusion with blood or blood products.
Excision of cervical or 1st rib.
Open or thoracoscopic cervical sympathectomy.
Chemical or surgical lumbar sympathectomy.
Debulking of soft tissue or ulcer with skin grafting.
Amputations of digits, trans-metatarsal, below knee, above knee.