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Article Review/Hyperlink |
Lim PO, MacFadyen RJ, Clarkson PBM, MacDonald TM
Impaired exercise tolerance in hypertensive patients
Ann Intern Med (Jan) 124:41-55 1996
In this review paper, Linn et. al address the need to perform exercise testing in hypertensive patients without suspected ischemic heart disease. The value of exercise tolerance testing in normotensives and patient with high-normal blood pressure as a predictor of future end organ damage is discussed, also. The differing efficacies of various hypertensive medications both at rest and during exercise are examined.
Either isometric or isotonic techniques can be used to evaluate and stress the cardiovascular system. Ergometric and treadmill testing are the two most widely used protocols, yet there are differences both in techniques and results. Systolic pressures are lower when comparing treadmill versus ergometric testing when patients are equally challenged. Oxygen consumption measures are used to assess exercise intensity due to the linear correlation between oxygen consumption and cardiac output. Studies are difficult to compare as often widely different exercise protocols have been used. In addition, some studies compare normal patients to patients with ischemic heart disease or to patients with cardiac failure. In some studies it is assumed that during exercise uncomplicated hypertensives have a normal oxygen consumption.
The importance of accurate diastolic pressure measurement during exercise testing is emphasized. Manual BP readings are difficult to obtain during exercise due to the patient movement, respiratory efforts and equipment noise. Diastolic pressure falls quickly at the end of exercise. This frustrates efforts to measure BP during exercise using a sphygmomanometer. Arterial pressures obtained using ambulatory monitors are unreliable during exercise testing. Intra-arterial monitoring is ideal but invasive.
In some studies, persons with an exaggerated BP rise during exercise are at a 2.1 to 3.4 fold risk of becoming hypertensive, although 40-90% remain normotensive in follow-up. Some studies find a relationship between exercise-induced hypertension and left ventricular hypertrophy (assessed by echocardiography), whereas others (such as the Framingham heart study) find no correlation. No controlled studies could be identified which associated hypertension during stress testing to nephropathy, retinopathy, or atherosclerotic vascular disease. These questions are fruitful areas for further research.
Commonly used antihypertensive medications and their relationship to hemodynamic response in arterial hypertension are analyzed. The treatment of hypertension should be adjusted according to underlying hemodynamic changes. Different stages of hypertension need different anti- hypertensive agents. Calcium channel blockers (such as verapamil and diltiazem), beta-blockers, drugs with both alpha and beta-receptor blocking ability (such as labetalol and carvedilol) and ACE inhibitors appear be the appropriate theraphy to control BP at both rest and exercise.
Comment: One major clinical point of this article is, that normotensive patients with an exaggerated hypertensive responses during exercise are at risk of developing high blood pressure at rest. (Danilo Perez-Monagas, M.D., Bowman Gray School of Medicine, Winston-Salem, NC)
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