作者简介：
Suzanne Oparil，美国伯明翰亚拉巴马大学医学院内科学教授，JNC8 编委组主席之一，曾任AHA主席，在血管生物和高血压领域成就卓越。
血压变异性是心脑血管事件的危险因素
首先必须强调，血压并不是一成不变的数值。最近的数据表明，除平均血压外，血压变异的幅度也是心血管事件和卒中的危险因素，根据统计学家的说法，在对平均血压进行校正后，血压变异性的危险程度高于平均血压。
血压变异重要性的早期研究是非常激进的，研究者直接插管对血压进行测量，但现在我们已经不再采用这种方法了。最新信息显示，每两次去诊室之间血压的血压变异性具有非常重要的预后价值。
血压变异性的原因及治疗
关于日内血压变异性的问题尚存在争议。我们所要做的并不仅仅是检测其对预后是否有价值，更要努力厘清引起血压变异的原因。有些理论认为血管硬化与血压变异性有关。颈动脉窦是主要的压力感受器。动脉硬化会导致颈动脉窦在血压上升时不能正常变形，所以不能正确感知血压进而对其进行调节。女性的血压变异性比男性更大。
一项荟萃分析显示有些药物（尤其是钙通道阻滞剂，如氨氯地平）在减小血压变异性方面优于其他药物；β受体阻滞剂似乎会导致血压变异性轻微增大；利尿剂虽然不如氨氯地平，但优于肾素-血管紧张素系统（RAS）阻滞剂。多数新的指南都将CCB或利尿剂作为老年高血压患者的一线治疗选择。
International Circulation: Can you introduce the main aspects of blood pressure variability that you want people to understand?
Prof. Oparil: First of all， blood pressure is not a constant number. It varies from beat to beat as your heart contracts. It varies from minute to minute and hour to hour. It is different in the daytime and at night. And recent studies have shown it varies from clinic visit to clinic visit. The recent data suggest that， in addition to just your average blood pressure， the amount of variability that occurs is a risk factor for cardiovascular events and stroke. This variability is correlated to mean blood pressure， but the statisticians – after correcting for mean blood pressure – say there is risk to be assigned to variability above and beyond mean blood pressure. So， in other words， the more your blood pressure jumps around， the worse off you are. That’s sort of a new concept.
The early studies that showed this is important were very aggressive. They did direct blood pressure measurements， meaning they put a catheter directly into an artery.We do not do that anymore. There was also ambulatory blood pressure monitoring over 24 hours showing that variation in daytime blood pressure is a risk factor， variation in nighttime blood pressure is a risk factor， if the blood pressure does not go down at night， that is another risk factor. That has been known for quite a while. The new information is in the analyses， mostly by the Oxford Group， showing blood pressure variability between visits to the healthcare provider’s office has prognostic significance.
International Circulation: Is it more significant than the variability within one day?
Prof. Oparil: That is what people think.There is a controversy now. The people who study the within-a-day variability say their information is more important. The people who examine visit-to-visit variability say their data are more important. We need not only to continue to test whether this variability has prognostic importance， but also to try to figure out what is causing this variability. Some theories say the variability is connected to the stiffness of blood vessels. As you get older， particularly if you have hypertension or diabetes or a lot of atherosclerosis， your vessels tend to get stiffer and that may contribute to variability. This would involve malfunction of the baroreflex. The dominant baroreflex is in the carotid artery. When the artery is stiff it does not deform properly when blood pressure increases， so it does not sense the blood pressure properly and does not regulate it. Women also tend to have a little more variability than men. Nobody knows what other pathophysiologic mechanisms might be causing the variability. I am working with an epidemiologist to study that issue. At this point， there are not too many clear signals about what causes blood pressure variability.
The causes of blood pressure variability are important， as is the question of whether certain treatments are better than others at dealing with it. It has been shown， in a meta-analysis by investigators in the Oxford Group， that some drug classes reduce variability more than others –specifically the calcium channel blockers， and more specifically amlodipine. Beta-blockers， which have been popular for hypertensive treatment for a long time， seem to make variability a little bit worse， almost the same as placebo. Diuretics are on the good side. They are better than RAS-blockers and certainly better than beta-blockers， though not quite as good as amlodipine in reducing variability. For older people， meaning those over 55 or 60 – and most people who come to the doctor for hypertension are older – most of the newer guidelines， the Japanese national guidelines and the NICE Guidelines from the UK， for example， have suggested either a CCB or a diuretic as first line therapy for older patients with hypertension， or some add RAS blockers also. It is important to remember that most older people with substantial blood pressure elevation require more than one antihypertensive drug anyway， so the fight over which is better to start with maybe a little bit unnecessary.This is why we had the Fixed Combination meeting.