It sounds like you are referring to a set of disorders called connective tissue disorders which can include Marfan Syndrome and Ehlers-Danlos Syndrome, among others. Patients with these sorts of conditions have very flexible joints (double-jointed) among other signs. The main heart condition that such patients have to be aware of is a thoracic aortic aneurysm. Basically, the wall of the aorta (the main artery in your body) is abnormal and can start to balloon up over time. Not all patients with these conditions will get a thoracic aortic aneurysm, but it should absolutely be screened for. This needs to be monitored with serial echocardiograms and, if it reaches a certain size, should be operated on. The risk of not treating a thoracic aortic aneurysm is eventual rupture or dissection, both of which are highly lethal. (John Ritter died of an ascending aortic dissection.) Hope that helps. P.S. If people don t know the answers to some of these questions, why do they post a response to say, I don t know! Is it just a ploy to earn points or something? The points are worthless!