LETTER TO THE EDITOR
Reply
Philip M. Mottram, MBBS, FRACP and
Thomas H. Marwick, MBBS, PhD, FACC
University of Queensland, Department of Medicine, Princess Alexandra Hospital, Ipswich Road, Brisbane Q4102, Australia
(Email: tmarwick{at}soms.uq.edu.au).
We thank Dr. O'Rourke for his comments in response to our study. Our report demonstrated that sensitive new myocardial measurements in normotensive patients who have a hypertensive response to exercise have abnormal left ventricular (LV) systolic and probably also diastolic behavior (1). We proposed that this phenomenon likely represents intrinsic damage to the myocardium,most probably from chronic exposure to "high-normal" levels of systemic blood pressure, which was present in these patients (1). Clearly, histological examination of myocardial tissue for hypertensive changes such as interstitial fibrosis would advance our understanding of the relevant mechanisms.
Dr. O'Rourke makes the important point that systolic pressure measured at the brachial artery is significantly influenced by wave reflection, and that central aortic pressure is a more important influence on LV systolic function. Central aortic pressure is influenced by arterial stiffness (2), but our preliminary findings are that, while arterial compliance (measured using the pulse pressure method using radial artery tonometry) was less in patients with a hypertensive response to exercise compared with controls (3), it was not related to indices of LV systolic function. Moreover, work in progress suggests that augmentation index using carotid tonometry is no different in those with a hypertensive response to exercise and control subjects. Thus, although we agree with Dr. O'Rourke that measurement of LV ejection duration or estimation of aortic systolic pressure during exercise may provide insight into the mechanism of a hypertensive response to exercise as recorded with cuff blood pressure at the upper limb, our preliminary data do not support a major association of LV systolic dysfunction with central hemodynamics.
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References
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1. Mottram PM, Haluska B, Yuda S, Leano R, Marwick TH. Patients with a hypertensive response to exercise have impaired systolic function without diastolic dysfunction or left ventricular hypertrophy J Am Coll Cardiol 2004;43:848-853.[Abstract/Free Full Text]
2. O'Rourke M. Arterial stiffness, systolic blood pressure, and logical treatment of arterial hypertension Hypertension 1990;15:339-347.[Abstract/Free Full Text]
3. Mottram PM, Haluska BA, Leano R, Yuda S, Marwick TH. Patients with a hypertensive response to exercise have impaired systolic function and reduced arterial compliance(abstr) Circulation 2002;106:II422.
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