Systolic hypertension
Encyclopedia
In medicine
, systolic hypertension is defined as an elevated systolic blood pressure.
If systolic blood pressure is elevated (>140) with a normal diastolic blood pressure (<90), it is called "isolated systolic hypertension".
, coronary ischemia
, and heart failure.
Contemporary physics shows us an Immersed Boundary Method
of computational illustration of a single heartbeat
. Applied to physiologic models, immersed boundary theory sees the heart as a great folded semisolid Sail
fielding and retrieving a viscous blood mass. The sail, likened to Windkessel
physiology gives and receives a load under time ordered phases. Decreasing compliance of the sail heralds the onset of systolic hypertension.
In addition to lifestyle changes, medication can also be used to reduce systolic hypertension to safe levels, although medications frequently have side effects, often serious. Two randomized controlled trial
s have established the value of treating systolic hypertension.
showed a reduction of three strokes per 100 patients treated for five years with chlorthalidone
showed a reduction of 0.3 strokes per 100 patients treated with nitrendipine
for a median follow-up of two years.
A meta-analysis
of individual-patient data from randomized controlled trial
s found that the nadir diastolic blood pressure below which cardiovascular outcomes increase is 85 mm Hg for untreated hypertensives and 85 mm Hg for treated hypertensives. The authors concluded "poor health conditions leading to low blood pressure and an increased risk for death probably explain the J-shaped curve". Interpreting the meta-analysis
is difficult, but avoiding a diastolic blood pressure below 68–70 mm Hg seems reasonable because:
Newer treatments have emerged since these trials which address the underlying causes of hypertension in novel ways. For instance, a direct inhibitor of the kidney hormone renin
, called aliskiren
, has recently been released in the United States. It has antihypertensive efficacy similar to ACE inhibitors and angiotensin receptor blockers
. By suppressing renin activity directly rather than indirectly (as these other medications do), it avoids a rebound in renin levels that gradually interferes with their efficacy. However, over the long term it may lead to increases in the physiological precursor of renin. Its role as a single agent without the concomitant use of other antihypertensives is not yet clear.
Medications that act on the sympathetic nervous system
, which is important in the cause of hypertension, also show promise. European studies show that selective imidazoline agonists, such as moxonidine and rilmenidine, are reasonably effective against hypertension while improving glucose tolerance and lipid metabolism.
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
, systolic hypertension is defined as an elevated systolic blood pressure.
If systolic blood pressure is elevated (>140) with a normal diastolic blood pressure (<90), it is called "isolated systolic hypertension".
Causes
Systolic hypertension may be due to reduced compliance physiology of the aorta with increasing age. This increases the load on the ventricle and compromises coronary blood flow, eventually resulting in left ventricular hypertrophyLeft ventricular hypertrophy
Left ventricular hypertrophy is the thickening of the myocardium of the left ventricle of the heart.-Causes:While ventricular hypertrophy occurs naturally as a reaction to aerobic exercise and strength training, it is most frequently referred to as a pathological reaction to cardiovascular...
, coronary ischemia
Coronary ischemia
Coronary ischemia is a medical term for not having enough blood through the coronary arteries. Coronary ischemia is linked to heart disease as well as heart attacks.It is also known as cardiac ischemia.-Causes:...
, and heart failure.
Contemporary physics shows us an Immersed Boundary Method
Immersed boundary method
The immersed boundary method is an approach – in computational fluid dynamics – to model and simulate mechanical systems in which elastic structures interact with fluid flows...
of computational illustration of a single heartbeat
Heartbeat
Heartbeat may refer to:* Cardiac cycle of the heart* Heart sounds* Pulse* The interval for keeping alive a push e-mail connection* Heartbeat , a British police drama* HeartBeat Heartbeat may refer to:* Cardiac cycle of the heart* Heart sounds* Pulse* The interval for keeping alive a push e-mail...
. Applied to physiologic models, immersed boundary theory sees the heart as a great folded semisolid Sail
Sail
A sail is any type of surface intended to move a vessel, vehicle or rotor by being placed in a wind—in essence a propulsion wing. Sails are used in sailing.-History of sails:...
fielding and retrieving a viscous blood mass. The sail, likened to Windkessel
Windkessel
Windkessel literally means air chamber and is a German translation of a concept described previousy by Stephen Hales, who likened the effect of the elastic arteries in dampening the arterial pulse to that of an air chamber in some 18th century fire engines...
physiology gives and receives a load under time ordered phases. Decreasing compliance of the sail heralds the onset of systolic hypertension.
Treatment
The goal of treating systolic hypertension is to delay and reduce the extent of damage to the heart, the cerebrovascular system, and the kidneys. Lifestyle interventions are a crucial element of successful treatment, including a diet low in sodium and rich in whole grains, fruits, and vegetables, such as a vegetarian or vegan diet. Clinical trials have also documented the beneficial effects of weight loss, increased physical activity, and limiting alcohol consumption.In addition to lifestyle changes, medication can also be used to reduce systolic hypertension to safe levels, although medications frequently have side effects, often serious. Two randomized controlled trial
Randomized controlled trial
A randomized controlled trial is a type of scientific experiment - a form of clinical trial - most commonly used in testing the safety and efficacy or effectiveness of healthcare services or health technologies A randomized controlled trial (RCT) is a type of scientific experiment - a form of...
s have established the value of treating systolic hypertension.
SHEP study
This randomized controlled trialRandomized controlled trial
A randomized controlled trial is a type of scientific experiment - a form of clinical trial - most commonly used in testing the safety and efficacy or effectiveness of healthcare services or health technologies A randomized controlled trial (RCT) is a type of scientific experiment - a form of...
showed a reduction of three strokes per 100 patients treated for five years with chlorthalidone
- Patients: inclusion criteria were SBP greater than 160 to 219 mm Hg and DBP less than 90 mm Hg. Mean initial BP was 170/77.
- Treatment goal: 20 mmHg reduction in systolic pressure or a systolic pressure of less than 160 mmHg, whichever was lower
- Mean final blood pressure in the treatment group: 143/68
Syst-Eur Trial
This randomized controlled trialRandomized controlled trial
A randomized controlled trial is a type of scientific experiment - a form of clinical trial - most commonly used in testing the safety and efficacy or effectiveness of healthcare services or health technologies A randomized controlled trial (RCT) is a type of scientific experiment - a form of...
showed a reduction of 0.3 strokes per 100 patients treated with nitrendipine
Nitrendipine
Nitrendipine is a dihydropyridine calcium channel blocker. It is used in the treatment of primary hypertension to decrease blood pressure....
for a median follow-up of two years.
- Patients: inclusion criteria were systolic of 160–219 mm Hg and diastolic blood pressure lower than 95 mm Hg. Average was 174/86.
- Treatment goal: "We aimed to reduce the sitting systolic blood pressure by at least 20 mm Hg to less than 150 mm Hg"
- Mean final blood pressure in the treatment group: 151/79. 44% of patients reached the target blood pressure goals.
The treatment goal
Based on these studies, treating to a systolic blood pressure of 140, as long as the diastolic blood pressure is 68 or more seems safe. Corroborating this, a re-analysis of the SHEP data suggest that allowing the diastolic to go below 70 may increase adverse effects.A meta-analysis
Meta-analysis
In statistics, a meta-analysis combines the results of several studies that address a set of related research hypotheses. In its simplest form, this is normally by identification of a common measure of effect size, for which a weighted average might be the output of a meta-analyses. Here the...
of individual-patient data from randomized controlled trial
Randomized controlled trial
A randomized controlled trial is a type of scientific experiment - a form of clinical trial - most commonly used in testing the safety and efficacy or effectiveness of healthcare services or health technologies A randomized controlled trial (RCT) is a type of scientific experiment - a form of...
s found that the nadir diastolic blood pressure below which cardiovascular outcomes increase is 85 mm Hg for untreated hypertensives and 85 mm Hg for treated hypertensives. The authors concluded "poor health conditions leading to low blood pressure and an increased risk for death probably explain the J-shaped curve". Interpreting the meta-analysis
Meta-analysis
In statistics, a meta-analysis combines the results of several studies that address a set of related research hypotheses. In its simplest form, this is normally by identification of a common measure of effect size, for which a weighted average might be the output of a meta-analyses. Here the...
is difficult, but avoiding a diastolic blood pressure below 68–70 mm Hg seems reasonable because:
- The nadir value of 85 mm Hg for treated hypertensives in the meta-analysisMeta-analysisIn statistics, a meta-analysis combines the results of several studies that address a set of related research hypotheses. In its simplest form, this is normally by identification of a common measure of effect size, for which a weighted average might be the output of a meta-analyses. Here the...
is higher than the value of 68–70 mm Hg that is the nadir suggested by the two major randomized controlled trialRandomized controlled trialA randomized controlled trial is a type of scientific experiment - a form of clinical trial - most commonly used in testing the safety and efficacy or effectiveness of healthcare services or health technologies A randomized controlled trial (RCT) is a type of scientific experiment - a form of...
s of isolated systolic hypertension - The two largest trials in the meta-analysisMeta-analysisIn statistics, a meta-analysis combines the results of several studies that address a set of related research hypotheses. In its simplest form, this is normally by identification of a common measure of effect size, for which a weighted average might be the output of a meta-analyses. Here the...
, Hypertension Detection and Follow-up Program (HDFP) and Medical Research Council trial in mild hypertension (MRC1) were predominantly middle aged subjects, all of whom had diastolic hypertension before treatment. - The independent contributions of diseases and factors other than hypertension versus effects of treatment are not clear in the meta-analysisMeta-analysisIn statistics, a meta-analysis combines the results of several studies that address a set of related research hypotheses. In its simplest form, this is normally by identification of a common measure of effect size, for which a weighted average might be the output of a meta-analyses. Here the...
.
Newer treatments have emerged since these trials which address the underlying causes of hypertension in novel ways. For instance, a direct inhibitor of the kidney hormone renin
Renin
Renin , also known as an angiotensinogenase, is an enzyme that participates in the body's renin-angiotensin system -- also known as the Renin-Angiotensin-Aldosterone Axis -- that mediates extracellular volume , and arterial vasoconstriction...
, called aliskiren
Aliskiren
Aliskiren is the first in a class of drugs called direct renin inhibitor. Its current licensed indication is essential hypertension....
, has recently been released in the United States. It has antihypertensive efficacy similar to ACE inhibitors and angiotensin receptor blockers
Angiotensin II receptor antagonist
Angiotensin II receptor antagonists, also known as angiotensin receptor blockers , AT1-receptor antagonists or sartans, are a group of pharmaceuticals which modulate the renin-angiotensin-aldosterone system...
. By suppressing renin activity directly rather than indirectly (as these other medications do), it avoids a rebound in renin levels that gradually interferes with their efficacy. However, over the long term it may lead to increases in the physiological precursor of renin. Its role as a single agent without the concomitant use of other antihypertensives is not yet clear.
Medications that act on the sympathetic nervous system
Sympathetic nervous system
The sympathetic nervous system is one of the three parts of the autonomic nervous system, along with the enteric and parasympathetic systems. Its general action is to mobilize the body's nervous system fight-or-flight response...
, which is important in the cause of hypertension, also show promise. European studies show that selective imidazoline agonists, such as moxonidine and rilmenidine, are reasonably effective against hypertension while improving glucose tolerance and lipid metabolism.