Archive for the ‘Cardiac Imaging’ Category
Share Our Mission to Heal
Holy Cross Hospital is seeking studio audience members for A Mission to Heal, a new show all about the heart.
Needed: 75 audience members for each show; Mix of demographics. No children under 18; Community groups are encouraged to have representation in the audience, as well as community leaders.
Where
A studio in Davie, FL. Details will be provided to audience members upon selection.
When
September 30, 2010; Refreshments will be served.
The show is not “live” but it is being recorded “live” so it will be edited and shown at a later date. Audience members should dress comfortably for long periods of sitting. No white blouses, shirts, hats or sweaters.
Please email info@holy-cross.com and put A Mission to Heal in the subject field OR call 954-776-3244 if you are interested in being part of the studio audience.
Please provide your full name, phone number, e-mail address, age range (20s, 30s, 40s, 50+) and race/ethnicity. Someone will be in touch to let you know if you have been selected and provide additional information.
How to Proceed?
If you fall into the age groups that I discussed in my last blog, what should you do? First, remember that this discussion is only about asymptomatic patients. Those that do not have a history of heart attack, stroke or do not suffer from claudication, which is pain in the legs on exertion.
First and foremost, if you are smoking stop, and after you stop, stay stopped. Believe me it is not so simple if you judge from what my patients tell me. Cholesterol levels are not the whole answer. There is no such thing as a normal cholesterol level. Each patient’s level is a number and then an atherogenicity potential. Although these can be determined by particle testing and such, our knowledge remains incomplete and our methods crude.
What has been proposed is finding a simple and reliable method to identify which patients have evidence of atherosclerotic changes in their vessels and then try to prevent the furtherance of the disease process by medical i.e. lipid lowering treatment. We have these methods available to us now and the article cited in my previous blog provides the background for these methods. One is calcium scoring by electron beam imaging.
It is fast, simple and accurate. However, it provides individuals with a small dose of radiation (median 2.3 mSv). If negative, it virtually excludes significant atherosclerosis and the chance of a cardiovascular event in 5-10 years is .6% at the greatest.
Another modality is carotid ultrasound which is done slightly differently than normal and looks at the intima- media and measures the thickness of it. This measurement has been shown to correlate with the disease process. It is not as predictive as calcium scoring but does not use radiation. It is not clear whether both tests are additive.
Imaging in this manner and using the SHAPE guidelines, it is estimated that almost 50% of the patients screened would be in a higher class and eligible for lipid lowering therapy. The cost of this screening varies, but some institutions offer it at around $150.
All of the information we have to date supports screening for all patients who have intermediate risk based on Framingham Risk Scores in addition to those patients with low HDLs. It is very unlikely that a large randomized study will ever be done. Who wants to be in the placebo group? We just have to manage with common sense.
Is it true that lipid lowering therapy saves lives? In my next blog I will explore that.
Vote for the Blog of the Year
Did Dr. Niederman post a blog in 2009 that you found particularly helpful? Was there a blog that you could not wait to share with someone else? We’d love to receive your feedback.
Please comment on what you think was Dr. Niederman’s best blog in 2009.
Cardiac Imaging and Radiation Exposure
On August 27, 2009 an article appeared in the NEJM discussing the long term risks of medical imaging utilizing ionizing radiation. This article and its accompanying editorial discuss all testing using ionizing radiation but I will focus on just the cardiovascular issues.
First some background. Radiation damage comes in two ways. 1) Deterministic injury which is usually direct skin damage, sunburn is a good example; and 2) Stochastic injury, which is the damaging of DNA (think melanoma) and leads to an increased probability of cancer in the future. The background risk of fatal cancer in men is 24% and 20% for women. This dose is cumulative over a lifetime, the higher the cumulative dose the higher the risk of developing a cancer.
We live on a radioactive planet and we all receive 53% of our total radiation from just being here. It ranges from 1.5-2.0 mSv here to 9.0 mSv in Denver. Average across the United States is 3.6 mSv. These figures are yearly. An average chest x-ray is .04mSv so on average we each receive about 90 chest x-rays a year.
This article discusses the large radiation exposure that patients receive from diagnostic cardiac imaging. If your TIMI risk score is low then an approach to the diagnostic work up can be “watchful waiting”. Imaging modalities such as stress testing without nuclear imaging and stress testing using echocardiography are also proven to assess cardiac risk and function without radiation.
Nuclear stress testing with the nuclear substance thallium was found to be the highest radiation test giving an average of 15.6 mSv (the equivalent of 173 Chest x-rays). This test alone accounts for 22.1% of the total radiation dose from all study procedures. Diagnostic cardiac catheterization is 7 mSv and for angioplasty about double at 15 mSv. CT cardiac angiography was several times higher than diagnostic cath but has been lowered considerably by the concept of “step and shoot” technique which lowers the dose and was not evaluated in this study as it occurred after the data collection period.
If you have risk but no symptoms it is quite possible that you could have a CT san followed by a nuclear stress test followed by cardiac cath and eventuating in a ptca of your heart artery. Most people could feel that they received state of the art testing and treatment. However as reviewed and discussed in the above cited articles this approach may not be the best approach in individual patients.
If your physician recommends an imaging test for you should discuss it in detail and understand the total dose of extra radiation that you might receive.
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