PATHOLOGIES OF CARDIOVASCULAR SYSTEM
The blood pressure reflects the ability of the arteries to stretch and fill with blood,
the efficiency of the heart as a pump, and the volume of circulating blood. Blood
pressure is affected by age, body size, diet, activity, emotions, pain, position,
gender, time of day, and disease states.
All these factors can have an impact on lowering or increasing the blood pressure.
Hypertension, or high blood pressure, is an important medical and public health
problem.
There is a direct relationship between hypertension and cardiovascular disease.
Hypertension is a repeatedly elevated blood pressure exceeding the 90-120mmHg
as systolic and 60-80mmHg of diastolic pressure. When measuring the blood
pressure, we are looking for the pressure during systole and diastole, and is
expressed as a fraction. The top number is the systolic blood pressure; the bottom
number is the diastolic blood pressure.
A. Systolic Blood Pressure
Systolic blood pressure is determined by the force and volume of blood that the left
ventricle ejects during systole and the ability of the arterial system to distend at the
time of ventricular contraction.
B. Diastolic Blood Pressure
Diastolic blood pressure reflects arterial pressure during ventricular relaxation
where the heart is being filled by blood either from his automatism functionality or
from venous return.
Classification of blood pressure for Adults age 18 years or older
The term hypertension, sustained elevations in systolic or diastolic blood pressure
that exceed prehypertension levels, is divided into two categories:
Stage 1 hypertension: is systolic blood pressure of 140 to 159 mm Hg or a diastolic
blood pressure between 90 and 99 mm Hg.
Stage 2 hypertension: is systolic blood pressure that equals or exceeds 160 mm
Hg or a diastolic pressure that equals or exceeds 100 mm Hg.
Other terminologies:
When elevated blood causes a cardiac abnormality, the term hypertensive heart
disease is used. When vascular damage is present without heart involvement, the
term hypertensive vascular disease is used.
When both heart disease and vascular damage accompany hypertension, the
appropriate term is hypertensive cardiovascular disease.
Causes and pathophysiology overview
A. Causes and Risk Factors
Basing on causes and risk factors, hypertension is divided into two main categories:
essential (primary; idiopathic) and secondary.
Primary (essential or idiopathic) hypertension: represent about 90-95% of all
hypertension cases. It is sustained elevated blood pressure with no known cause.
Although the exact cause of primary hypertension is unknown, there are several
contributing factors which include increased sympathetic nervous system activity,
overproduction of sodium-retaining hormones and vasoconstricting substances,
increased sodium intake, overweight, diabetes mellitus, tobacco use, and excessive
alcohol consumption.
Essential hypertension also may develop from alterations in other body chemicals
such as defects in blood pressure regulation resulting from an impairment in the
renin-angiotensin-aldosterone mechanism.
Secondary hypertension: is elevated blood pressure with a specific cause that often
can be identified and corrected. It results from some other disorders such as kidney
disease, pheochromocytoma (a tumor of the adrenal medulla), hyperaldosteronism
(increased secretion of mineral corticoid by the adrenal cortex), atherosclerosis,
use of cocaine or other cardiac stimulants (e.g., weight-control drugs, caffeine), and
use of oral contraceptives. This type of hypertension accounts for 5% to 10% of all
hypertension cases. It should be suspected in people who suddenly develop high
blood pressure, especially if it is severe.
Treatment of secondary hypertension is aimed at removing or treating the underlying
cause. Secondary hypertension is a contributing factor to hypertensive crisis.
Hypertension is the most prevalent modifiable risk factor for most of cardiovascular
diseases, being more common than cigarette smoking, dyslipidemia, or diabetes,
which are the other major risk factors. Hypertension often coexists with these other
risk factors as well as with overweight/obesity, an unhealthy diet, and physical
inactivity. The presence of more than one risk factor increases the risk of adverse
cardiovascular events.
Pathophysiology Overview
Hypertension results from a sustained increase in peripheral resistance (arteriolar
vasoconstriction), an increase in circulating blood volume, or both. Chronic
hypertension damages the walls of systemic blood vessels.
Signs and symptoms
Hypertension is often called the silent killer because it is frequently asymptomatic
until it becomes severe and targeted organ disease occurs. A patient with severe
hypertension may experience a variety of symptoms secondary to the effects on
blood vessels in the various organs and tissues or to the increased workload of
the heart. These secondary symptoms include fatigue, dizziness, palpitations,
angina/chest pain, and dyspnea. Headache, nosebleeds and bleeding from other
organs might come when the blood pressure is very high. However, patients with
hypertensive crisis may experience severe headaches, dyspnea, anxiety, and
nosebleeds.
Investigations
Most hypertension is not classified as primary hypertension, testing for secondary
causes should be routinely done. Basic laboratory studies are performed to:
• Identify or rule out causes of secondary hypertension,
• Evaluate target organ disease,
• Determine overall cardiovascular risk, or
• Establish baseline levels before initiating therapy.
Basic diagnostic studies performed in a person with hypertension are the following:
1. Full blood count (FBC) to assist in establishing the baseline levels before
initiating the therapy or detect infection if any.
2. Routine urinalysis, bilirubin urea and nitrogen (BUN), liver function tests
(ASAT, ALAT) and serum creatinine levels used to screen for renal and
liver involvement and to provide baseline information about kidney and liver
function.
3. Measurement of serum electrolytes (sodium, potassium, chloride), especially
potassium, is important to detect hyperaldosteronism, a cause of secondary
hypertension.
4. Blood glucose levels (serum glucose) assist in the diagnosis of diabetes
mellitus.
5. A lipid profile (total lipids, triglycerides, cholesterol) provides information
about additional risk factors related to atherosclerosis
6. Uric acid levels establish a baseline, since the levels often rise with diuretic
therapy.
7. An electrocardiogram (ECG) provides baseline information about cardiac
status. It can identify the presence of cardiac ischemia, or previous
myocardial infarction, etc.
8. Ophtalmic examination: may reveal vascular changes in the eyes, retinal
hemorrhages, or edema of the optic nerves, known as papilledema.
Blood pressure measurement is the initial strategy and the gold standard to
confirm the diagnosis of hypertension in most patients. In practice, blood pressure
measurement is simple and quick and should be performed at every clinical
encounter.
When hypertension is suspected or confirmed based on blood pressure readings,
a physical examination and all related investigations should be performed to
determine the extent of target-organ damage if any. Look for the presence of
cardiovascular or kidney disease, the presence or absence of other cardiovascular
risk factors, lifestyle factors that could potentially contribute to hypertension,
potential interfering substances (eg, chronic use of nonsteroidal antiinflammatory
drugs, estrogen-containing oral contraceptives) that can lead to hypertension.
The physical examination should include the funduscopic examination to evaluate
for hypertensive retinopathy and must be able to detect/predict all other possible
complications.
Treatment plan
Goals include achieving and maintaining normal blood pressure and reducing
cardiovascular risk and target organ disease. This treatment plan includes lifestyle
modifications and medications:
1. Weight reduction: overweight persons have an increased incidence of
hypertension and increased risk for cardiovascular diseases. When a person
decreases caloric intake, sodium and fat intake are usually also reduced.
Although reducing the fat content of the diet has not been shown to produce
sustained benefits in blood pressure control, it may slow the progress of
atherosclerosis and reduce overall cardiovascular diseases risk.
2. Dietary sodium and potassium reduction: this involves avoiding foods
known to be high in sodium and not adding salt in the preparation of foods
or at meals.
3. Avoid/Moderation of alcohol consumption,
4. Regular physical activity: physically active lifestyle is essential to promote
and maintain good health. Physical activity is more likely to be done if it is
safe and enjoyable, fits easily into one’s daily schedule, and is inexpensive.
People with hypertension must increase their physical activity. Advise
sedentary people to increase activity levels gradually.
5. Avoidance of tobacco use (smoking and chewing), and
6. Management of psychosocial risk factors.
7. Medications: the drugs currently available for treating hypertension have
two main actions: (1) they decrease the volume of circulating blood and (2)they reduce systemic vascular resistance. The drugs used in the treatment of
hypertension include diuretics, the adrenergic inhibitors, direct vasodilators,
angiotensin and renin inhibitors, and calcium channel blockers.
1. Health promotion: Primary prevention of hypertension is a cost-effective
approach. Current recommendations for primary prevention include lifestyle
modifications that prevent or delay the rise in blood pressure in at-risk people.
2. Blood Pressure Measurement: Initially, take the blood pressure in both
arms to note any differences. Proper size and correct placement of the blood
pressure cuff are critical for accurate measurement.
3. Screening Programs: screening programs in the community are widely
used to check individuals for high blood pressure. At the time of the blood
pressure measurement, give each person a written, numeric value of the
reading. If necessary, explain why further evaluation is needed. Effort and
resources should focus on the following: (1) controlling blood pressure
in persons already identified as having hypertension; (2) identifying and controlling blood pressure in at-risk groups such as obese people, and
relatives of people with hypertension; and (3) screening those with limited
access to the health care system.
4. Monitoring of Patient Adherence to medications and regimen: A major
problem in the long-term management of the patient with hypertension
is poor adherence with the prescribed regimen. The reasons for poor
adherence include inadequate patient teaching, unpleasant side effects of
drugs, return of blood pressure to normal range while on medication, lack
of motivation, high cost of drugs, lack of insurance, and lack of a trusting
relationship between the patient and the health care provider.
Also assess the patient’s diet, activity level, and lifestyle as additional
indicators of adherence. Individually assess patients to determine the
reasons why the patient is not adhering to the treatment and develop a
plan with the patient to improve adherence. The plan should be compatible
with the patient’s personality, habits, and lifestyle. Active patient participation
increases the likelihood of adherence to the treatment plan. Measures
such as including the patient in the development of a medication schedule,
selecting medications that are affordable, and involving caregivers help
increase patient adherence.
Substituting combination drugs for multiple drugs once the BP is stable may
also facilitate adherence. Combination drugs reduce the number of pills the
patient has to take each day and may reduce costs. It is important to help
the patient and caregiver understand that hypertension is a chronic illness
that cannot be cured. Emphasize that it can be controlled with drug therapy,
diet changes, physical activity, periodic follow-up, and other relevant lifestyle
modifications.
Evolution and complications of hypertension
and kidney outcomes. Each of the complications is closely associated with the
presence of hypertension
Regardless of whether a person has essential or secondary hypertension, the
accompanying organ damage and complications are the same. Hypertension
causes the heart to work harder to pump against the increased resistance. The extra
work and the greater mass increase the heart’s need for oxygen. If the myocardium
doesn’t receive sufficient oxygenated blood, myocardial ischemia occurs and the
client experiences angina. Consequently, the size of the heart muscle increases.
When the heart no longer can pump adequately to meet the body’s metabolic needs,
heart failure occurs. In addition to its direct effects on the heart, high blood pressure
damages the arterial vascular system. It accelerates atherosclerosis. Furthermore,
the increased resistance of the arterioles to the flow of blood causes serious
complications in other body organs, including the eyes, brain, heart, and kidneys.
Hemorrhage of tiny arteries in the retina may cause marked visual disturbances
or blindness. A cerebrovascular accident (stroke) may result from hemorrhage or
occlusion of a blood vessel in the brain. Myocardial infarction (MI) may result from
occlusion of a branch of a coronary artery. Impaired circulation to the kidneys may
result in renal failure
In summary, the complications of hypertension are:
– Hypertension emergency
– Atherosclerotic coronary artery disease
– Myocardial ischemia/ infarction
– Heart failure
– Renal Failure
– Stroke/ Cerebral hemorrhage/ Cerebral ischemia
– Aortic aneurysm
– Retinal vascular sclerosis
– Gangrene of extremities
Hypertensive Crisis:
Hypertensive crisis is a term used to indicate either a hypertensive urgency or
emergency. This is determined by the degree of target organ disease and how
quickly the blood pressure must be lowered.
A hypertensive emergency develops over hours to days. It is a situation in which
a patient’s blood pressure is severely elevated (often above 220/140 mm Hg) with
clinical evidence of target organ disease. It can cause encephalopathy, intracranial
or subarachnoid hemorrhage, acute left ventricular failure, myocardial infarction,
renal failure, dissecting aortic aneurysm, and retinopathy.
Hypertensive urgency develops over days to weeks. This is a situation in which a
patient’s blood pressure is severely elevated (usually above 180/110 mm Hg), but
there is no clinical evidence of target organ disease.
Prompt recognition and management of hypertensive crisis are essential to decrease
the threat to organ function and life. Hypertensive crisis occurs more often in patients
with a history of hypertension who have not adhered to their medication regimens
or who have been under-medicated. In such cases, rising blood pressure is thought
to trigger endothelial damage and the release of vasoconstrictor substances.
Clinical Manifestations
A hypertensive crisis is often manifested as hypertensive encephalopathy, a
syndrome in which a sudden rise in blood pressure is associated with severe
headache, nausea, vomiting, seizures, confusion, and coma. Patients can have
chest and back pain, dyspnea, and possibly reduced or absent pulses in the
extremities.
Management of Hypertensive crisis:
Blood pressure level alone is a poor indicator of the seriousness of the patient’s
condition. It is not the major factor in deciding the treatment for a hypertensive
crisis. The link between elevated blood pressure and signs of new or progressive
target organ disease determines the seriousness of the situation. Hypertensive
crisis require hospitalization, intravenous administration of antihypertensive drugs
and intensive care monitoring.