Dear Proud Momma,
What the cardiologist has drawn for you is a couple of examples of the left coronary artery arising from the right coronary artery. As he said, the middle drawing is the one that can be problematic. In this drawing, the left coronary artery courses between the pulmonary artery and the aorta, the two great arteries. It is problematic because as cardiac output increases, such as with exercise, there is a combination of dilation of the great arteries, which can compress the left coronary artery, with increased metabolic need of the heart muscle. This can lead to decreased blood flow to the heart muscle cells at a time of increased need, which can lead to potentially lethal heart rhythm abnormalities or a myocardial infarction, with death of the heart muscle. Unfortunately, echocardiography is not always correct in ruling out this problem. There have been reports of examples of patients in which the echocardiogram appeared normal (despite the possible concern), only to have it proven abnormal by a different imaging modality. As to why this was not felt to be a problem previously, without seeing the studies or evaluating your son or his records, I cannot say for sure. I will say that diagnosis of coronary artery anomalies is not always straightforward on echocardiography. It is certainly not 50-50, but due to the combination of the small size of the structures plus the inherent limitations of the use of ultrasound in bigger children and adults, smaller anatomical structures cannot always be confirmed.
Either cardiac MRI or CT scanning, if performed in an experienced pediatric and congenital center, should confirm the anatomy of the coronary arteries appropriately. If an anomalous coronary artery coursing between the great arteries is found, another consideration may be a nuclear medicine stress test to assess for evidence of decreased blood flow to the heart muscle. Neither Ehlers-Danlos nor Marfan syndrome are specifically associated with congenital coronary artery anomalies. Also, without evaluating your son, I cannot comment on his concern of right-sided chest pain, although this is typically non-cardiac in nature.
With a single coronary artery and assuming that the arterial course is not compressed by the great arteries, the biggest risk is not until later in adulthood. If there is atherosclerosis of the main coronary artery, it could be much more devastating if there was decreased blood flow to that main artery, leading to a more global heart attack. Therefore, ensuring appropriate exercise, diet, weight, and lipid levels would be important. Getting good dietary and exercise habits young would be more helpful. In the absence of a family history, lipid evaluation during early adolescence would be fine.
Thank you so much for your reply :) It def shed some light on a few things. I hope to hear soon when his testing will be done and will surely look into a nuclear medicine stress test if he comes back life threatening in nature. We have been through so much with him already, his decompression surgery and years of struggling to understand his many various anomalies, I just want him to be healthy so he can enjoy life. It will be great to finally understand the entire picture instead of just puzzle pieces. While I am confused as to why it wasnt a concern 2 years ago I guess I should be greatful that now we can explore it more for peace of mind. The only thing I am still unsure of is if the artery doesnt pass between the great arteries is there still any sort of risks compared to a typical person since it is still just a single versus a double? Perhaps the answer will depend on if he is symptomatic or not. Time will tell. Thanks so much again! Robin ~