Professor Michael O'Rourke, MD DSc FRACP FACC FESC AMLaboratory Head, Cardiac Physiology and Transplantation DivisionEmeritus Professor, University of New South Wales
|
 |
Research activity is an extension of the approach initiated by mentors DA McDonald and MG Taylor, who first applied standard engineering approaches, including frequency domain analysis to the study of pulsatile arterial phenomena.
While these pioneers studied physiological phenomena exclusively, we have extended their approaches to study of human aging and human arterial disease. Special focus has been the ill-effects of arterial stiffening with age on pulse wave transmission and reflection, and on how such disturbance adversely effects left ventricular load and function upstream, and small vessels downstream. We have shown that ill-effects are far greater than estimated in the past from conventional recordings of arterial pressure with the brachial cuff sphygmomanometer.
We have introduced the technique of arterial tonometry (developed with H. Millar, Houston), and new methods for analysing and interpreting the arterial pulse, as recorded non-invasively at the wrist, or from the carotid artery in the neck. New techniques permit aging change and effects of disease on ventricular/vascular interaction to be assessed easily and non-invasively.
To date we have established a number of specific uses, including enhanced ability to detect and monitor effects of drugs on vital organs, to detect the difference between systolic and diastolic ventricular dysfunction as the cause of cardiac failure, to assess severity of systolic dysfunction in heart failure, to explain the mechanism for exercise-induced angina in persons with normal coronary arteries, to identify spurious systolic hypertension in youth, and to explain benefits of entrainment between stride and heart rate in long-distance running.
The study of arterial aging has shown that changes are progressive from childhood, that these explain decline in athletic performance through middle age and frank cardiac failure in the elderly together with small vessel disease in brain and kidney, and that these are due to the fatiguing effects of cyclic stress on arterial walls and excessive pulsatile shear stress on the arterial lining.
Through application of McDonald's and Taylor's approach to clinical problems, we had predicted that interpretation of diastolic blood pressure in hypertension should be re-evaluated, and that in older humans, systolic and pulse pressure would be the best predictors of cardiovascular events in population studies. Such predictions have been confirmed throughout the world and have led further to measurement of central aortic perssure as the best guide to prognosis in epidemiological studies and clinical trials.
For research in arterial hemodynamics, Michael O'Rourke was awarded the Bjorn Folkow Prize by the European Society of Hypertension in 2000 and his principal collaborator ME Safar of Paris, the Zanchetti Award from European Society of Hypertension in 1999.
A NIH ROI grant has been approved for three years (P.I. Teresa Tsang, Mayo Clinic), dealing with determinants of atrial fibrillation and cardiac failure in the elderly. This involves assessment of arterial stiffness through pulse waveform analysis. I am a co-investigator in this study. Other co-investigators include J. Seward, B. Gersch.
Entirely separate work has been directed to improve survival of heart attack outside hospital. This has introduced defibrillators to all ambulances in New South Wales, and to all international Qantas aircraft, and has evaluated pre-hospital thrombolysis. The Qantas initiative, introduced and supervised by Michael O'Rourke with Eric Donaldson of Qantas, has established a new industry standard, with American, Delta, United, Varig, Cathay Pacific, British Airways and other airlines introducing similar programs. Since April 2004, all commercial airliners in the USA with one or more cabin attendants are required to carry a defibrillator.
Michael O'Rourke is assisting St. John Ambulance in development of a national program of public access defibrillation. St. John Ambulance train over 250,000 persons in resuscitation and first aid each year in Australia and is busily involved in introduction of public access defibrillation as an extension to the professional ambulance service.
This program has received grants in excess of $1 million from the Federal Government and IAG (NRMA Inusrance) and has received two Federal Government prizes (Pre-disaster Category in the National Safer Communities Award 2005.
Co-Investigators:
Alberto Avolio, PhD; University of NSW, Sydney
Teresa Tsang, PhD; Mayo Clinic, MN, USA
Collaborators:
Wilmer Nichols PhD; University of Florida
Kenji Takazawa MD; Cardiology Dept, Tokyo Medical University
Michel Safar MD; Dept of Medicine, Hotel Dieu, Paris
Stan Franklin MD; University of California (Irvine)
Bryan Williams MD, Department of Cardiovascular Sciences, University of Leicester, UK
Ion Morrison; Qantas Airways
Liu Lisheng; Cardiovascular Institute, Chinese Academy of Medical Science, Beijing
Vlachopoulos Charalambos; Athens Medical School, Hippokration Hospital, Athens, Greece
Kozo Hirata; Omiya Medical Center, Jichi Medical School, Saitama, Japan
Jan Staessen; Hypertensie en Cardiovasculaire Revalidatie Eenheid, Leuven, Belgium
Thomas Weber; Cardiology Department General Hospital of the Kreuzschwestern, Wels, Austria
Alfredo Pauca; Wake Forest University School of Medicine, Winston-Salem, USA
Jim Seward; Mayo Clinic, Rochester, MN, USA
Selected Publications:
Nichols WW, O'Rourke MF. McDonald's Blood Flow in Arteries, 5th ed. London: Arnold 1998
Safar ME, O'Rourke MF. Arterial stiffness, Handbook of Hypertension, 23rd edition, Elsevier, Edinburgh 2006 [in press].
O'Rourke MF, Safar ME. Relationship between aortic stiffening and microvascular disease in brain and kidney: cause and logic of therapy. Hypertension. 2005; 46:200-4
Pauca AL, Kon ND, O'Rourke MF. Benefits of nitroglycerine on arterial stiffness is directly due to effects on peripheral arteries. Heart 2005 Mar 10; [Epub ahead of print]
Williams B. and The CAFE investigators for the ASCOT investigators. Differential impact of blood pressure lowering drugs on central aortic pressure and clinical outcomes-Principal results of the Conduit Artery Function Evaluation study: The CAFE study. Circulation 2006 [in press]
O'Rourke MF. Beyond Blood Pressure; subtle effects of drug classes. (Invited editorial) ATVB 2005; 25:2238-39.
Back to top
