Out of the blue, about 6 years ago, around the same time I went from small fiber PN to then include large fiber PN, I developed a right bundle branch block of the heart. Of course, I said a what? No known heart issues with immediate family members. Primary doc caught it on a routine checkup and was referred to a cardiologist. Various tests confirmed right bundle branch block which apparently is not that uncommon. Tied to PN? Cardiologist was not sure. In my case, I think there is a connection to the PN because of the timing and other side effects. Ed