While cath labs are often used to look at how the heart functions and its blood supply, the same techniques with minor variations in equipment can be used to examine any of the blood vessels in the entire body. The heart and all of the associated blood vessels of the body are collectively called the cardiovascular system. Specially equipped cath labs can be used to diagnose and treat many conditions of the entire cardiovascular system. ACI’s main cath lab uses a revolutionary new technology called flat detector technology which offers the best possible imaging quality available today. Additionally, the particular model used by ACI is designed to be extremely useful in viewing the heart as well as the blood supply to other areas of the body, and is called a combination lab.
Apart from the circulatory system, there are other body systems in which fluid travels in vessel-like structures to its final destination. Examples are the biliary system in which bile is produced and travels to the stomach; and the urinary system in which urine is produced by the kidney and travels to the bladder and eventually out of the body. Sometimes diseases of these systems which cause obstruction of flow can be diagnosed and treated in the cath lab in manners similar to the circulatory system.
These applications of the Cath Lab and imaging in general to diagnose and treat conditions outside of the heart without the use of open surgery is called Interventional Radiology.
There are many aspects of interventional radiology, however, in this section, we will focus on those related to cath labs and in particular those offered by the Interventional Radiology department at ACI.
Peripheral Angiography and Angioplasty
Cath labs are commonly used to investigate the blood supply to the legs and lower body and in particular to look for blockages of the leg’s blood supply, a condition called peripheral artery disease.
Peripheral Artery Disease (PAD) is a common condition that often goes untreated until it’s too late. It usually affects persons over the age of 50 and is extremely common in patients with diabetes. It is caused by the build up of cholesterol and scar tissue inside of the blood vessels, a process called atherosclerosis, which is also responsible for heart disease and stroke in other parts of the body. The most common symptoms of early peripheral artery disease as defined by the American Heart Association is leg pain described as a painful cramping of the hips, thighs or calves when walking, climbing stairs or exercising. In the early stage of the disease, this pain will usually go away when you have stopped exercising. In the later stages and more severe stages of the disease the symptoms are:
- Leg pain that doesn’t go away when you stop exercising
- Foot or toe wounds that won’t heal or heal very slowly
- A marked decrease in the temperature of your lower leg or foot particularly compared to the other leg or to the rest of your body.
It is important to know that the pain associated with peripheral artery disease is in the muscles and not the joints. Often this pain is considered a normal sign of aging and dismissed but this is not so. Peripheral artery disease is a serious but treatable condition. If the disease is left untreated, persons can lose their limbs. We therefore strongly advise persons experiencing these symptoms to see their doctor and describe as clearly as possible the symptoms they are experiencing. For more information please call our office and ask for our head nurse who will schedule an appointment for you to see a PAD specialist and have the necessary tests performed.
PAD is usually first diagnosed simply by looking for weak pulses in the legs and by taking blood pressures in the arms and the legs and making comparisons to derive a measure called the ankle-brachial index (ABI). Further testing can then be done as necessary using ultrasound, CT scans and MRI scans to get images of the blood supply to the legs. Once it is determined that treatment is required, the doctor will then refer the patient to have a peripheral angiogram in a cath lab and in some cases treatment can be done at the same time by a technique called peripheral angioplasty. In other instances treatment may be done by surgery.
Peripheral Angiography is a special angiogram looking at the blood supply to the legs. As described earlier, a thin plastic tube called a catheter is inserted into a blood vessel in the groin area through a small puncture in the skin. The catheter is then guided using X-rays to the blood supply of the legs and a special X-ray dye is injected into the blood vessel. Sophisticated X-ray movie pictures are taken as dye travels through the vessels from the top to the bottom of the leg. Once completed, the peripheral angiogram gives a detailed picture of all of the blood vessels in the leg clearly showing any blockages that might be present and their exact location.
In some instances the doctors may advise that the best treatment for the blockages is a technique called peripheral angioplasty. This technique is very similar to interventional techniques used to open blockages in the blood supply to the heart. In peripheral angioplasty once the area of the blockage has been identified then another catheter is carefully advanced under X-ray guidance to the blockage. At the tip of this second catheter is a balloon. This balloon is inflated once in position, in order to reopen the area of the blockage. The result is the restoration of the blood supply and the catheters are removed. The patient usually leaves the hospital on the same day of the procedure and the recovery is very quick.
While not as common, the same techniques described above can be applied to blockages in the blood supply to the arms once the condition is diagnosed.
Renal Angiogram and Angioplasty
The same principles outlined in the diagnosis and treatment of peripheral artery disease can be applied to the treatment of a condition called renal artery stenosis.
Renal artery stenosis describes a condition in which the blood supply to one of the kidneys is blocked or narrowed.
When referred to a cath lab for the treatment of renal artery stenosis, the first step is the performance of a renal angiogram to get a detailed picture of the blood supply to the kidney.
Once the blockage has been located on the angiogram, renal angioplasty may be performed using a balloon catheter, as described earlier, whereby the deflated balloon is carefully positioned at the point of the blockage and is then inflated to re-open the blocked artery.
Aortic Aneurysm Repair
An aneurysm is defined as a localized weakening in the wall of a blood vessel causing the affected area of the vessel to bulge outwards under the pressure of the blood flowing within it. The bulging of the vessel wall is a very serious condition since there is a risk that the weakened vessel wall may rupture leading to severe internal bleeding which may be life threatening.
Aneursyms are especially dangerous when they occur in the body’s largest artery which is called the aorta. The aorta is referred to as a “great vessel” because of its large size and is effectively the main pipeline from the heart from which all other blood vessel get their blood supply. As such aortic aneurysms are a serious life threatening condition that require immediate medical treatment.
Certain types of aortic aneurysms may be treated in a non-surgical fashion within the Cath Lab. The technique is called endovascular aortic stent grafting.
This technique uses a large implantable stent graft to effectively seal off the aneurysm and thereby reduce the risk of rupturing.
The stent graft similar to the stents used in coronary intervention is an expandable tube that is designed to fit snugly inside of the target vessel. However, in the case of the aortic stent graft, the walls of the stent graft are lined with a special fabric which does not allow blood to flow through. The key to the technique therefore is to place the stent graft in such a way that one end of the stent graft is before the start of the aneurysm and the other end is after the aneurysm. Blood is therefore prevented from getting to the weakened walls of the aneurysmal artery.
Advanced Cardiovascular Institute was the first to do this procedure in Trinidad and is arguably the most experienced centre for aortic aneurysm stenting in the Southern Caribbean.
Antegrade Ureteric Stenting
The high quality X-ray imaging available in the cath lab can also be used to do interventional radiology procedures on body areas other than the cardiovascular system.
One common use is in the treatment of a blockage of the tubes that drain the kidney (called the ureters) which leads to a high pressure within the kidney that can cause permanent damage.
One of the common treatments involve the placement of a plastic stent within the ureter to restore the urine flow out of the kidney. This is usually done by a urologist using a scope placed in the urinary tract. This is called the retrograde placement of the ureteric stent. However, in some instances, the blockage may be so tight that it does not allow the placement of the stent in this fashion.
In these instances, the stent can be placed in the ureter by making a tiny puncture in the kidney and placing the stent through the kidney and into the ureter. This is called the antegrade placement of a ureteric stent and is usually done by an interventional radiologist.
The X-ray equipment in a catheterization laboratory is ideal for guiding the placement of the ureteric stent in this fashion and ACI has done many of these procedures.