1From the Departments of Pharmacotherapy and Cardiology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
Requests for reprints to P. A. van Zwieten, Academic Medical Centre, Universiteit Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
Received 4 July 1996 Revised 18 November 1996 Accepted 26 November 1996
