Lowering of blood pressure and artery stiffness
1997; Elsevier BV; Volume: 349; Issue: 9056 Linguagem: Inglês
10.1016/s0140-6736(05)62734-1
ISSN1474-547X
Autores Tópico(s)Renal function and acid-base balance
ResumoThere seems to be some confusion about the mechanisms underlying the so-called J-shaped relation between diastolic blood pressure and mortality. Sleight (Feb 1, p 362)1Sleight P Lowering of blood pressure and artery stiffness.Lancet. 1997; 349: 362Summary Full Text Full Text PDF PubMed Scopus (3) Google Scholar suggests that a recent article by one of us (EDL)2Lehmann ED Pulse wave velocity as a marker of vascular disease.Lancet. 1996; 348: 744Summary Full Text Full Text PDF Google Scholar "drew attention to possible adverse effects … when diastolic blood pressure is lowered too much". However, nowhere in this article2Lehmann ED Pulse wave velocity as a marker of vascular disease.Lancet. 1996; 348: 744Summary Full Text Full Text PDF Google Scholar was such a suggestion made. Indeed we have previously written in The Lancet drawing attention to some of the drawbacks to conjecture about the mechanism underlying the J-shaped relation3Lehmann ED Hopkins KD Gosling RG Relation between aortic atherosclerosis and blood pressure.Lancet. 1994; 343: 1106-1107Abstract PubMed Scopus (7) Google Scholar.In support of a complex hypothesis Sleight cites the work of Witteman and colleagues4Witteman JCM Grobbee DE Valkenburg HA et al.J-shaped relation between the change in diastolic blood pressure and progression of aortic atherosclerosis.Lancet. 1994; 343: 504-507Summary PubMed Scopus (214) Google Scholar highlighting that in post-menopausal women who did not develop aortic calcification diastolic pressure rose with age, whereas diastolic pressure progressively fell with age with increasing degrees of aortic calcification. These workers reported that "a decline in diastolic pressure was associated only with severe atherosclerotic progression"4Witteman JCM Grobbee DE Valkenburg HA et al.J-shaped relation between the change in diastolic blood pressure and progression of aortic atherosclerosis.Lancet. 1994; 343: 504-507Summary PubMed Scopus (214) Google Scholar. However, they never actually measured vessel stiffness. Rather, they based their entire assessment on plain abdominal radiographs, which do not provide a sensitive method of studying the elastic properties of the aorta. The absence of a J-shaped relation between change in diastolic blood pressure and slight progression of atherosclerosis in the Witteman study4Witteman JCM Grobbee DE Valkenburg HA et al.J-shaped relation between the change in diastolic blood pressure and progression of aortic atherosclerosis.Lancet. 1994; 343: 504-507Summary PubMed Scopus (214) Google Scholar may well have arisen from the fact that the technique used would be at its most unreliable when detecting slight progression of atheroma formation. In Witteman and colleagues' own words from an earlier report on this topic "the radiological method used for screening purposes will miss many cases of atherosclerosis"5Witteman JCM Kok FJ Saase van JLCM Valkenburg HA Aortic calcification as a predictor of cardiovascular mortality.Lancet. 1986; ii: 1120-1122Summary Scopus (253) Google Scholar. Therefore their data would a priori be more biased to severe atherosclerotic progression, since this would be what their radiographic technique could most readily detect.As such, in addition to the prospective clinical trials highlighted by Sleight1Sleight P Lowering of blood pressure and artery stiffness.Lancet. 1997; 349: 362Summary Full Text Full Text PDF PubMed Scopus (3) Google Scholar—if there is a wish to actually elucidate the underlying mechanism—we suggest that arterial stiffness should be measured non-invasively with one of the various techniques of demonstrated reliability that are readily available for this purpose. These include doppler ultrasound phase-locked echo-tracking devices for accurately assessing the change in vessel diameter of a given arterial cross-section during the cardiac cycle, and doppler ultrasound, applanation tonometry, or magnetic-resonance imaging for assessing the velocity of the pulse wave as it travels along a given arterial segment. All these approaches allow vascular stiffness to be determined non-invasively, and have been shown to be reproducible and sensitive indicators of changing arterial biophysical properties.In view of the ready availability of these techniques it seems curious that 10 years after the original hypothesis for the J-shaped curve was published, people are still debating the role of arterial stiffness in the mechanism, without having actually measured this index of the vasculature. Correlation of vessel stiffness with diastolic blood pressure and vascular events would settle the question. There seems to be some confusion about the mechanisms underlying the so-called J-shaped relation between diastolic blood pressure and mortality. Sleight (Feb 1, p 362)1Sleight P Lowering of blood pressure and artery stiffness.Lancet. 1997; 349: 362Summary Full Text Full Text PDF PubMed Scopus (3) Google Scholar suggests that a recent article by one of us (EDL)2Lehmann ED Pulse wave velocity as a marker of vascular disease.Lancet. 1996; 348: 744Summary Full Text Full Text PDF Google Scholar "drew attention to possible adverse effects … when diastolic blood pressure is lowered too much". However, nowhere in this article2Lehmann ED Pulse wave velocity as a marker of vascular disease.Lancet. 1996; 348: 744Summary Full Text Full Text PDF Google Scholar was such a suggestion made. Indeed we have previously written in The Lancet drawing attention to some of the drawbacks to conjecture about the mechanism underlying the J-shaped relation3Lehmann ED Hopkins KD Gosling RG Relation between aortic atherosclerosis and blood pressure.Lancet. 1994; 343: 1106-1107Abstract PubMed Scopus (7) Google Scholar. In support of a complex hypothesis Sleight cites the work of Witteman and colleagues4Witteman JCM Grobbee DE Valkenburg HA et al.J-shaped relation between the change in diastolic blood pressure and progression of aortic atherosclerosis.Lancet. 1994; 343: 504-507Summary PubMed Scopus (214) Google Scholar highlighting that in post-menopausal women who did not develop aortic calcification diastolic pressure rose with age, whereas diastolic pressure progressively fell with age with increasing degrees of aortic calcification. These workers reported that "a decline in diastolic pressure was associated only with severe atherosclerotic progression"4Witteman JCM Grobbee DE Valkenburg HA et al.J-shaped relation between the change in diastolic blood pressure and progression of aortic atherosclerosis.Lancet. 1994; 343: 504-507Summary PubMed Scopus (214) Google Scholar. However, they never actually measured vessel stiffness. Rather, they based their entire assessment on plain abdominal radiographs, which do not provide a sensitive method of studying the elastic properties of the aorta. The absence of a J-shaped relation between change in diastolic blood pressure and slight progression of atherosclerosis in the Witteman study4Witteman JCM Grobbee DE Valkenburg HA et al.J-shaped relation between the change in diastolic blood pressure and progression of aortic atherosclerosis.Lancet. 1994; 343: 504-507Summary PubMed Scopus (214) Google Scholar may well have arisen from the fact that the technique used would be at its most unreliable when detecting slight progression of atheroma formation. In Witteman and colleagues' own words from an earlier report on this topic "the radiological method used for screening purposes will miss many cases of atherosclerosis"5Witteman JCM Kok FJ Saase van JLCM Valkenburg HA Aortic calcification as a predictor of cardiovascular mortality.Lancet. 1986; ii: 1120-1122Summary Scopus (253) Google Scholar. Therefore their data would a priori be more biased to severe atherosclerotic progression, since this would be what their radiographic technique could most readily detect. As such, in addition to the prospective clinical trials highlighted by Sleight1Sleight P Lowering of blood pressure and artery stiffness.Lancet. 1997; 349: 362Summary Full Text Full Text PDF PubMed Scopus (3) Google Scholar—if there is a wish to actually elucidate the underlying mechanism—we suggest that arterial stiffness should be measured non-invasively with one of the various techniques of demonstrated reliability that are readily available for this purpose. These include doppler ultrasound phase-locked echo-tracking devices for accurately assessing the change in vessel diameter of a given arterial cross-section during the cardiac cycle, and doppler ultrasound, applanation tonometry, or magnetic-resonance imaging for assessing the velocity of the pulse wave as it travels along a given arterial segment. All these approaches allow vascular stiffness to be determined non-invasively, and have been shown to be reproducible and sensitive indicators of changing arterial biophysical properties. In view of the ready availability of these techniques it seems curious that 10 years after the original hypothesis for the J-shaped curve was published, people are still debating the role of arterial stiffness in the mechanism, without having actually measured this index of the vasculature. Correlation of vessel stiffness with diastolic blood pressure and vascular events would settle the question. 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