Hypertension Flashcards
• Definition • Rationale (prevalence and prognosis) • Regulation of blood pressure • Pathophysiology • Treating hypertension • Exercise prescription
At what systolic and diastolic values does the positive relationship between blood pressure and CVD risk start?
The positive relationship between CVD risk and blood pressure (BP) occurs with a BP as low as 115/75 mm Hg and doubles for each 20/10-mm Hg increase
How do systolic blood pressure and diastolic blood pressure change with increasing age?
BP increases with age. SBP continues to increase throughout adult life, secondary to progressive arterial stiffening, whereas DBP plateaus in the sixth decade and decreases thereafter
According to the authors, what proportion of people with hypertension are currently taking antihypertensive medication to reduce their symptoms and risk of complications?
29%
Why is accurate prediction of future hypertension important? What are some of the generally accepted predictors of future hypertension?
o Accurate prediction of future HTN in persons with normal BP is important so that early preventive measures can be taken to potentially alter this outcome
o Resting BP, family history of HTN, body mass index, and physical activity and fitness are generally accepted predictors of future HTN.
What is the evidence statement regarding the exercise as a tool in the prevention of hypertension?
o Higher levels of physical activity and greater fitness at baseline are associated with a reduced incidence of HTN in white men, and these associations persist after appropriate multivariate analysis.
o The few studies in women and the one study in black subjects did not show significant relationships; however, the paucity of data precludes definitive conclusions regarding the role of sex and ethnicity.
Why might ‘ambulatory blood pressure’ monitoring be a more valuable prognostic tool than a ‘casual’ (one-off resting BP) measure?
The magnitude of PEH appeared to be less in the few studies using ambulatory BP monitoring compared with those using casual BP measurements, yet the smaller decreases in BP could be of greater clinical significance because ambulatory BP is a more valid prognostic indicator of CVD
Which variable makes the largest contribution to the magnitude of the post exercise change in blood pressure??
The variable that makes the largest contribution to the change in BP after exercise appears to be the preexercise value
How short and light do the authors suggest an exercise bout may be in order to induce post-exercise hypotension?
PEH is a low-threshold event, with BP reductions occurring with exercise durations as short as 3 min and exercise intensities as low as 40% V˙ O2max
What is the evidence statement regarding the use of resistance exercise in the treatment of high blood pressure?
Resistance training performed according to ACSM guidelines reduces BP in normotensive and hypertensive adults
Describe the J-shaped curve relationship between activity intensity and long-term risk observed by the British Regional Heart Study.
The long-term risk of major CVD events was reduced as patients were more active, up to moderately vigorous activity, but the risk increased again in vigorously active men, particularly in the presence of other risk factors
What is Poiseuille’s Law?
As derived from Poiseuille’s law, TPR is directly proportional to blood viscosity and length of the vessel, but inversely proportional to the fourth power of the radius.
A possible mechanism for blood pressure reduction with regular exercise is a reduction in sympathetic nervous system activity. Describe how reduced SNS activity might reduce blood pressure.
o Sympathetic nerve activity (SNA) and the subsequent release of norepinephrine (NE) mediate vasoconstriction and increase vascular resistance.
o Reductions in central sympathetic nerve outflow or circulating NE attenuate vasoconstriction and lead to reductions in BP
How might exercise induced increases in endothelial nitric oxide production improve blood pressure regulation?
o Improved endothelial-dependent mediated vasodilation is an important training adaptation to reduce peripheral resistance in HTN.
o Reducing peripheral resistance results in a reduction in blood pressure due to the increased vasodilation
Describe some the structural adaptations to the vascular that are induced by regular exercise. How might these benefit blood pressure?
o These include vascular remodeling (i.e., increased length, cross-sectional area, and/or diameter of already existing arteries and veins) and angiogenesis (i.e., new vessel growth)
o Therefore, the training-induced alterations in vascular structure (i.e., increased muscle precapillary vessel number) that elevate the total cross-sectional area of resistance vessel lumina suggest a possible mechanism to lower peripheral resistance and reduce resting BP
What mechanisms might potentially contribute to acute post exercise hypotension?
Two prominent mechanisms have been proposed to explain the decrease in peripheral resistance: sympathetic inhibition and altered vascular responsiveness after exercise:
o Reductions in sympathetic outflow after exercise have been reported in both animals and humans. It appears the arterial and cardiopulmonary baroreflexes are important for PEH
o Have questioned the importance of this mechanism. Changes in vascular responsiveness related to PEH are associated with decreased transduction of sympathetic outflow to vascular resistance and the release of local vasodilator substances induced by muscle contraction and augmented muscle blood flow (e.g., nitric oxide released)
