- Importance of internal controls, statistical methods, and side effects in short-term trials of vasodilators: a study of hydralazine kinetics in patients with aortic regurgitation. McKay, C.R., Nana, M., Kawanishi, D.T., Elkayam, U., Chandraratna, P.A., Weiss, J.N., Rahimtoola, S.H. Circulation (1985)