An ascending aorta so thin that the writing on a ruler can be read directly through the wall. An ascending aorta so thin that the writing on a ruler can be read directly through the wall. It is sobering to think that this was all the tissue restraining the bloodstream and blood pressure in this patient. It is presumed that MMPs participated in the underlying destruction of the aortic wall that resulted in such loss of substance. MMP, matrix metalloproteinases. John A Elefteriades et al. Open Heart 2015;2:e000169 ©2015 by British Cardiovascular Society