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Howard LeWine, M.D., is chief editor of Internet Publishing at Harvard Health Publications. He is recognized as an outstanding clinician and teacher and is a recipient of the Internal Medicine Teacher of the Year award at Brigham and Women's Hospital. Dr. LeWine continues to practice Internal Medicine; most recently he became a hospitalist after practicing primary care for over 20 years.
Question:
For the past two months I have experienced increased shortness of breath. I have chronic asthma, but there's concern the shortness of breath could be caused by a blockage in heart. I have experienced difficulties in the past when anesthetized. Is there an effective alternative to heart catheterization? I've read about a new CT scan — is it recommended?
Answer:
Diagnosing the cause of shortness of breath in someone with risk factors for both lung and heart disease is a common challenge. For someone who already has asthma or some other lung condition, I first ask whether the shortness of breath is similar to the usual symptoms when the lung disease acts up. Even when the symptoms are quite similar, I still worry that it may be the heart.
Blood tests for B-type natriuretic peptide (BNP) and troponin can be helpful. High BNP levels usually indicate some degree of heart failure. An elevated troponin suggests ongoing heart muscle damage, usually from a blocked coronary artery.
If both of these tests are normal, some non-invasive tests can predict whether there is significant blockage of one or more coronary arteries. An echocardiogram, done with or without a drug to raise the heart rate, often provides enough information. Other types of stress tests can also help make the diagnosis.
You may already have had these tests with inconclusive results. This happens often, especially with women.
Each person's medical situation is different. You and your doctor must decide the next best step.
While the new CT scans and MRIs of the heart show promise, cardiac catheterization is still the standard when blocked arteries might be the cause of significant symptoms.
The other advantage of cardiac catheterization over CT or MRI is that the blockage can often be fixed with angioplasty during the procedure.