Diastolic pressure definition

A-F This straight line represents the ESPVR. If a ventricle is taken and filled to volume a , it will generate pressure A at the end of systole. When filled to volume b it will generate pressure B and so on. Each ventricle will have a curve specific to its overall function but a standard example is shown below. Changes in contractility can alter the gradient of the line, a-f This curve represents the ED PVR. When the ventricle is filled to volume a it will, by definition, have an end-diastolic pressure a . When filled to volume b it will have a pressure b and so on. The line offers some information about diastolic function and is altered by changes in compliance, distensibility and relaxation of the ventricle. 

The actual level of pressure that can be considered hypertensive is difficult to define it depends on a number of factors, including the patient s age, sex, race, and lifestyle. As a working definition, many cardiovascular treatment centers consider that a diastolic pressure of 90 mm Hg or higher or a systolic pressure of 140 mm Hg or higher represents hypertension. In this chapter, ref-... 

Hypertension, whether labile or fixed, borderline or definite, casual or basal, systolic or diastolic, at any age regardless of gender is the most common and a powerful contributor to atherosclerotic coronary vascular disease. Morbidity and mortality increase progressively with the degree of elevation of either systolic or diastolic pressure and pulse pressure, and no discernible critical value exists (see Chap. 13). Numerous trials have documented the reduction in risk associated with blood pressure lowering however, most of these studies show that mortality and morbidity reduction is a result of fewer strokes and... 

The controversy as to whether antihypertensive therapy really prevents complications and alters the mortality prognosis has definitely been settled in favor of drug treatment. The historic Veterans Administration Cooperative Study on antihypertensive agents showed conclusively that major complications in patients with severe hypertension (diastolic pressure of 115-129 mmHg) were reduced by a factor of 27 (Veterans Administration, 1967, 1970). Even patients with moderate hypertension (105-114 mmHg) were found to have morbidity decreased by 4 1. 

Step 2 is then to run the trial and compute the 95 per cent confidence interval for the difference, Pi — P2> in the mean reductions in diastolic blood pressure. In the above example suppose that this 95 per cent confidence interval turns out to be ( — 1.5 mmHg, 1.8 mmHg). As seen in Figure 12.2, all of the values within this interval are compatible with our definition of non-inferiority the non-inferiority of the test treatment has been established. In contrast, had the 95 per cent confidence interval been, say, (—2.3 mmHg,... 

In experimental animals the effect of ephedrine administered intravenously is similar to that of epinephrine. The arterial pressure — systolic, diastolic, and mean pressure — rises and vagal slowing occurs. Compared with epinephrine, the pressor response to ephedrine occurs somewhat more slowly and lasts about ten times longer. Furthermore, it requires more ephedrine than epinephrine to obtain an equivalent pressor response. How much more depends on the species tested, type and degree of anesthesia, dose level, and individual variability of the test animal. It is, therefore, almost impossible to give a definite figure for the relative potency of ephedrine and epinephrine. It is commonly accepted that it requires about 250 times more ephedrine than epinephrine to achieve equipressor responses. 

A plethora of substances are normally employed to lower the blood pressure, though their efiect may be transient. A few of them are used for their hypotensive action. An arbitrary definition of normal adult blood pressme afforded by the World Health Organization (WHO)- is a systolic pressnre eqnal to or below 140 mm Hg together with a diastolic pressnre equal to or below 90 mm Hg. ... 

FIGURE 8.2 Time-varying ventricular elastance curves measured using the definition in Equation 8.3. Measured elastance curves are distinctive in shape. (Adapted from Suga, H. and Sagawa, K. 1974. Instantaneous pressure-volume relationship under various end-diastolic volume. Circ Res. 35 117-126.)... 

The development of practical methods for the assessment of myocardial contractility continues and while the ESP-ESV concept provides one approach for quantitating changes in the contractile state, it requires further modification in order that it may be employed for patient to patient comparison. The preliminary studies described here on the basis of the developed stress concept shows some promise, however, further studies are required to examine the relationships between peak systolic pressure and end diastolic volume in order to explore an alternative definition for developed stress. 

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