With the degree of coronary artery disease (CAD) and peripheral vascular disease (PVD) in our society, procedures such as cardiac catheterizations and angiograms have saved both lives and limbs. These procedures have helped many patients open up clogged and diseased arteries, maintaining the blood flow of the heart and keeping their extremities intact. The above two procedures are referred to as percutaneous (perk-yu-tane-eus) interventions, as they access internal organs through a small puncture in the skin.
|How To Treat Kidney Disease|
In these interventions, a cardiologist, vascular surgeon, or other trained doctor needs to look at the blood flow of the heart or extremity. To get an accurate assessment of the degree of blockage, it is necessary for the doctor to inject dye.
If a blockage is present in the artery, a specific type of intervention - an angioplasty (opening a narrowed vessel with a type of balloon) - may be performed. If needed, a stent, which is a device placed in the artery to keep the blood flow open, will be added. If this is the case, more dye may be needed to better see the affected area. As before, the more dye that is used the higher the risk of the kidney being affected. Other risks of this "dye nephropathy" include CKD, diabetes, and dehydration.
There are important precautions you can take to reduce these risks. Your doctor may suggest the following:
- You may be asked to come to the hospital one day before the procedure to get some intravenous fluids. Doing this keeps your kidneys "flushed" and is the best thing you can do to reduce the dye risk.
- Your doctor may ask you to take Mucomyst, an oral form of Nacetylcysteine (NAC), starting one day prior to the procedure. NAC is an herbal supplement with antioxidant activity. Taken twice a day for two days, it may have a protective effect on the kidney.
- If you are on the medication metformin (Glucophage) for diabetes, you will be asked to stop taking this medication for forty-eight hours prior to the procedure.
- Stop taking the ACE inhibitor/ARB at least twenty-four hours prior to the procedure.
Between a Rock and a Hard Place
Procedures like cardiac catheterizations occur when people are in the hospital. A common scenario that doctors see is this:
A man comes into the hospital because of chest pain. He has both advanced CKD and bad heart disease. A cardiac catheterization is requested. In this scenario, both doctor and patient are between a rock and a hard place.
Without the cardiac catheterization, the man will likely continue to have heart problems. If the cardiac catheterization is performed, however, there is a risk of worsening kidney function, especially in the setting of advanced kidney disease. So what is the right answer to this situation?
The entire medical team will discuss all of the options with the patient. In the above scenario, without a cardiac intervention the heart will not get any better. Here, the man and his family elected to go ahead with the heart catheterization. He was given intravenous fluids and Mucormyst one day prior to the procedure. Fortunately, his kidney function remained stable.
In a situation like this, there are sometimes no right answers. In helping the heart, the kidneys can be affected. This is an example of why communication with the other members of the medical team and the patient is so important.
Magnetic Reasonance Imaging (MRI) and the Use of Gadolinium
In addition to CAT scans, MRIs are a common type of imaging procedure your doctor may order. Like CAT scans, they can be done with or without contrast. The type of contrast used in MRI studies, however, is called gadolinium (gad-o-lin-eum). There have only been a few reports of MRI studies where gadolinium has been used and blamed as causing kidney failure. The more significant risk may be a skin condition called nephrogenic systemic fibrosis (NSF).
NSF was initially discovered several years ago when people would complain to their doctors about a bronzing or thickening of the skin. Biopsies of those areas revealed gadolinium in the layers of the skin. It was thought that the use of MRI, particularly in those with advanced kidney disease (GFR < 30 ml/min), increased the risk of this process. How this happens is still not quite known, and as of yet there is no recommended treatment.
If your doctor requests that you get an MRI, ask if the study is truly needed. If so, ask if gadolinium needs to be given. When it does, ask what will be done to minimize the potential toxicities of the suggested study. Depending on your kidney function, your doctor may suggest avoiding the use of gadolinium altogether (less than 30 percent) unless it is absolutely needed.
It is important to understand the effects of the medications and imaging studies your doctor may prescribe for you. With every medication, every imaging study, and every procedure, it is important to assess the risks and benefits. Will this medication benefit me? Could this imaging study or procedure hurt me or my kidneys in any way? If you have kidney disease, and even if you don't, it is sometimes important enough to ask your doctor when not to take a medication as well as when to take one. To find out more, you can check out How To Treat Kidney Disease.