For an 18 year old to have a blockage is very extremely rare, but symptoms do need to be evaluated.
If your heart has episodes of rapid heart rate, you should get checked for cardiac conduction abnormalities such as wolff parkinson white syndrome. These type of abnormalites occur at any age.
You might also benefit from an "event monitor" which is a device you wear and press a button when symptoms happen. It will transmit what your heart is doing during the symptoms. sometimes you get checked when you are NOT having symptoms and everything is normal. But you need to be checked when the symptoms are actually happening.
Did your doctor listen to your neck? Did he hear a bruit? A bruit is not something that it "might" be, either you have one or you don't. It sounds like a swishing sound when you put the stethoscope on the neck. Did the doctors listen to the neck? If the cardiologist listened and there was no sound, it would explain why he did not do the ultrasound. However, you still have the symptoms, and a "bruit" does not cause those symptoms. And vertigo is not caused by carotid blockage, but rather vertebro-basilar artery blockage. So, wrong blood vessel anyhow. But do get the event monitor.
If your heart has episodes of rapid heart rate, you should get checked for cardiac conduction abnormalities such as wolff parkinson white syndrome. These type of abnormalites occur at any age.
You might also benefit from an "event monitor" which is a device you wear and press a button when symptoms happen. It will transmit what your heart is doing during the symptoms. sometimes you get checked when you are NOT having symptoms and everything is normal. But you need to be checked when the symptoms are actually happening.
Did your doctor listen to your neck? Did he hear a bruit? A bruit is not something that it "might" be, either you have one or you don't. It sounds like a swishing sound when you put the stethoscope on the neck. Did the doctors listen to the neck? If the cardiologist listened and there was no sound, it would explain why he did not do the ultrasound. However, you still have the symptoms, and a "bruit" does not cause those symptoms. And vertigo is not caused by carotid blockage, but rather vertebro-basilar artery blockage. So, wrong blood vessel anyhow. But do get the event monitor.