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PH2113 The Heart > 2. Pathophysiology of hypertension > Flashcards

2. Pathophysiology of hypertension Flashcards

1
Q

What is the Ideal blood pressure?

A

from 90/60 to 120/80 is the ideal healthy blood pressure

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2
Q

What is the normal (average) blood pressure in our population?

A

The ‘normal’ blood pressure in the population is from 120/80 to 140/90 which is too high. Many of the population are at the stage of ‘pre-hypertension’

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3
Q

What is classified as ‘high blood pressure’?

A

Any value over 140/90

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4
Q

What are the values in the BP reading x/y?

A

Systolic pressure of the heart / Diastolic pressure of the heart

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5
Q

What does Systolic and Diastolic mean?

A

Systolic is the pressure in the arteries during contraction of the heart muscle
Diastolic is the pressure in the arteries between contraction (between beats)

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6
Q

What does blood pressure provide?

A

A driving force for blood to perfuse into organs

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7
Q

What does BP determine?

A

It determines Tissue Perfusion Pressure

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8
Q

Where is BP measured and why?

A

BP is measured at the level of the heart so normally on the left arm of the patient, because blood pressure varies through out the body due to reasons such as gravity.

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9
Q

Why is BP cyclial (regular)?

A

Due to the Cardiac Cycle: the sequence of events that happens when the heart beats.

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10
Q

What are the main 5 things that affect the BP?

A

Peripheral Resistance (arteries resistance)
Mean Arterial Pressure (MAP)
Blood Volume
Cardiac Output (CO)
Venous Return (VR)
Many of these affect each other and in the end can cause hypertension

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11
Q

What does a decreased VR mean?

A

This means less blood is returning to the heart, which decreases the Filling Pressure, decreases CO, and therefore decreases BP.

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12
Q

What is the Mean Arterial Pressure?

A

This is defined as the Average pressure in the arteries during one cardiac cycle.

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13
Q

What is the major component that affects peripheral resistance, and what does this go on to affect?

A

Resistance to Flow affects Peripheral reistance which goes on to affect MAP

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14
Q

What are the factors affecing resistance to flow?

A

Viscosity of the blood
Length of the vessles
Radius of the vessel.

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15
Q

Which one of the factors affecting resistance to flow is the major determinant?

A

The radius of the vessel in the equation i to the power of 4, therefore a small change in the radius of the vessel will have a big effect on the Resistance to flow, which goes on to affect peripheral resistance and then MAP

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16
Q

What is Vasoconstriction in relation to resistance to flow?

A

The radius of the vessels becomes smaller, and the resistance to flow increases.

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17
Q

Why does vasoconstriction or vasodilation affect peripheral resistance?

A

Any change in the smooth muscle tone withe constrict or dilate, will change the radius of the vessels and therefore the resistance to flow and peripheral resistance.

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18
Q

What does increased peripheral resistance result in?

A

Increased peripheral resistance leads to increased MAP which leads to Increased BP

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19
Q

What type of vessel contributes the most to changes in the peripheral resistance?

A

The Arterioles = Branches of the arteries leading to the capillaries.

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20
Q

What does ‘blood pressure; a regulated variable’ mean?

A

The blood pressure naturally changes throughout the day e.g. it decereases at night, and increases during exercise and these are all normal changes regulated by the body.

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21
Q

What does a ‘continuous variable’ mean in relation to BP?

A

These are risk factors that don’t change the BP immediately e.g. obeisity and smoking. They cause a change in blood pressure continuously over time.

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22
Q

Define Hypertension:

A

This is an increase in blood pressure that is associated with an increase risk of harm (not increase blood pressure that happens normally throughout the day like during excercise). It is related to the Continuous Variable of the BP.

23
Q

What is the protocol for a patient who is pre-hypertension’?

A

Pre-hypertension is anything above 120/80, but below 140/90. To avoid becoming hypertensive and cause end organ damage, lifestyle changes should be recommended, and educate the patient on why these changes need to be made.
Diet, alcohol, smoking, excercise, reduce salt intake, stress etc.

24
Q

What is the protocol for confirming hypertension for someone with a BP reading of >140/90?

A

If not previously diagnosed, offer Ambuatory Blood Pressure Monitoring to confirm the diagnosis of Hypertension.
If patient does not want ABPM, offer Home Blood Pressure Monitoring to confirm diagnosis.
These should rule out White-Coat Syndrome.

25
Q

What is the intervention if hypertension stage 1 is confirmed?

A

Stage 1 = >140/90 mmHg
If below 80 and has stage 1 hypertension with 1 of the following:
-End organ damage,
-Established CVD
-Diabetes
-Renal Disease
-10 year CV risk of 20% or more
then pharmacological intervention is required.
If do not fit into these categories, then life style advice should be sufficient to decrease BP.
If the patient is younger than 40, and does not fit to any of the list above, then referr for specialist evaluation of secondary causes of hypertension.

26
Q

What is stage 2 hypertension and what is the intervention?

A

Stage 2 hypertension is a BP of 160/100 mmHg.
All patients presenting with stage 2 hypertension should have pharmacological intervention regardless of age and complications.
Their target blood pressure is to get below 140/90, but if diabetic or have CV disease, then target is 130/80.

27
Q

Stage 3 hypertension is:

A

A BP reading of 180/110 mmHg or over and these are at serious risk of CVD.

28
Q

Other than the stages of hypertension, what are the different descriptions of hypertension?

A
  1. Prehypertension
  2. Essential/Primary Hypertension
  3. Secondary Hypertension
  4. Isolated systolic/diastolic hypertension
  5. White coat hypertension
  6. Malignant Hypertension - Emergancy
29
Q

Describe Primary / Essential Hypertension

Include the causes, what patients will suffer from, risk factors.

A

This is idiopathic hypertension and is >90% of cases of hypertension. It is multifactorial from the environment to the genes. Patients with this tend to suffer from increased total peripheral resistance.
There is altered renin output and increased salt sensitivity.
The risk factors include obeisity, alchohol, smoking, etc
There is often NO increase in Cardiac Output

30
Q

Describe Secondary Hypertension.

A

This accounts for about 5% of hypertension cases. It is hypertension as a consequence of an identibfiable physiological, pharmacological, or structural cause.

31
Q

Give examples of diseases that may cause Secondary Hypertension

A

Renovascular disease: Polycystic disease (genetic) or Renal Artery Stenosis which causes narrowing of the arteries in one or both kidneys
Adrenal Disease: Hyperaldosteronism (Conn’s syndrome) causing low renin levels
Pregnancy: Can be either Pre-eclamsia which is hypertension with protein in the urine or Gestastional which is hypertension without protein in the urine.
Drugs: Oral contraceptives, NSAIDs, Steroids, Codeine, Amphetamine

32
Q

What are the less common causes of Secondary Hypertension?

A

Sleep apnoea, Thyroid and parathyroid disease. Tumour of the adrenal gland, Congenital (from birth) structural abnormalities.

33
Q

Who should be considered to have secondary hypertension?

A 
If below 40 and haven't got any of the below factors:
End organ damage,
Established CVD
Diabetes
Renal Disease
10 Year CV risk >20%
34
Q

Describe Pre-hypertension: And what is the intervention, if any:

A

120/80 - 140/90 mmHg
This is a warning of possible Hypertension. Lifestyle changes like improved diet and increased excercise will help to improve. REquires regular monitoring of BP

35
Q

Describe Isolated Hypertension

A

This can be systolic or diastolic, where on is too high, but the other in the healthy range.
If the systolic is over 160, but the diastolic 90, this is classed as Systolic Isolated Hypertension.
If systolic is 120, but diastolic 110, then this is described as Diastolic Isolated Hypertension.

36
Q

What is the intervention with Isolated Hypertension

A

Will have to be treated with pharmacological intervention, but lifestyle advice is beneficial if required e.g. if smoking then recommend to stop.

37
Q

Describe the White Coat hypertension and how to overcome.

A

This is when the patient’s blood pressure increases due to anxiety and stress of being in a medical environment so it does not give a true reading of the blood pressure.
To overcome this, tell patient to relax, breathe slowly, and to not be nervous about the readings.
If the BP reading is high, and hypertension needs to be confirmed, then give ABPM, or HBPM to rule out white coat.

38
Q

Malignant Hypertension: What is this?

A

This is a sudden onset of extremely high BP that can cause end organ damage. It is treated as a medical emergancy - A&E

39
Q

What are the 5 organ systems involved in Hypertension?

A 
Heart
Brain (CNS)
Endocrine Systems
Blood Vessels
Renal System
40
Q

What must Hypertension be associated with (1 of 4 choices)

A

Increased Heart Rate
Increased Myocardial contractilty - muscular tissue of the heart contracting more
Increased arterial constriction
Increased blood volume

41
Q

What is often the primary cause of Hypertension?

A

Raised total peripheral resistance is often the primary cause, causing an increase in MAP, and therefore hypertension

42
Q

What causes elevated Total Peripheral Resistance?

A

30-60% is a genetic factor. There is greater incidence in African-Americans and in individuals with a family history of salt-sensitiviteis.
Liddle’s syndrome
Environmental influences e.g. obeisity, stress, alcohol
Vascular Remodelling
Vasoactive substances
Hyperinsulinemia and Hyperglycaemia

43
Q

What is Liddle’s syndrome?

A

A single gene causing increased activity of the epithelial Sodium channel resulting in the kidney excreting Potassium, but retaining Sodium and Water leading to hypertension.

44
Q

What are the vasocative substances that may cause elevated TPR?

A 
Increased Endothelin-1 (ET-1) = vasoconstrictor
Increased Noradrenaline (NAd) = vasoconstrictor
Increased Angiotensin II = vasoconstrion
Decreased Nitric Oxide (NO) = vasoconstriction
45
Q

What is Hyperinsulinemia and Hyperglycemia

A

Hyperinsulinemia is too much insulin in the blood causing increased uptake in Sodium from the kidney = increased BP
Hyperglycemia is Diabetes which can cause hardening of the arteries, causing an increase in BP

46
Q

Renin Angiotensin Aldosterone system (RAAS). What is this system?

A

This involves the liver and the kidney. ANGIOTENSINOGEN is secreted from the liver and RENIN is secreted from the juxtaglomerular cells of the kidney and converts Angiotensinogen to Angiotensin I.
ACE enzyme then converts Angiotensin I to form Angiotensin II.

47
Q

What does Angiotensin II cause??

A

Angiotensin II causes:

  • Increased ADH secretion which increases Water absorption in the kidney
  • Increased sympathetic activity - increases the HR
  • Increased Arteriolar Vasoconstriction causing an increase in resistance to flow and BP
  • Increased aldosterone production causing an increase in Sodium Chloride and water reabsorption and increased Potassium excretion.
48
Q

What does Aldosterone do appart from increase in Sodium Chloride and water reabsorption and increased Potassium excretion?

A

It works in a negative feedback, causing a decrease in Renin production to then decrease the amount of Angiotensin I (and therefore Angiotensin II) produced.

49
Q

What are the two groups of renin-involved hypertension?

A

HIGH RENIN LEVELS AND LOW RENIN LEVELS

50
Q

How does High renin levels cause hypertension?

A

High renin levels causes an increase in Angiotensin I which is converted to Angiotensin II. This then causes all the things previously mentioned, but the most substantial effect on hypertension is the increased potassium excretion, increased sodium and water retention.

51
Q

How does Low renin cause Hypertension?

A

This is when there is a failure to increase the Renin levels if sodium levels are low in the blood. Low renin is associated with high levels of aldosterone, and the negative feedback loop is when there is high aldosterone levels, the renin levels decrease. Low-renin hypertensives have a higher juxta-glomerular perfusion pressure and a disease often associated with this is Conn’s disease

52
Q

What ethnic group is most likely to have Low-Renin hypertension and why?

A

It is more common in African-Americans due to differences in renal sodium handling.

53
Q

Salt sensitivity: How does salt effect the Blood pressure?

A

Salt is Sodium Chloride. The blood pressure responds to dietry salt intake. Some people can effectively increase salt without increasing their BP, but others cannot excrete dietry salt in High concentrations without causing an increase in blood pressure. These individuals are salt sensitive.
It is an alteration in the kidney where an increase in NaCl requires an increase in arterial pressure to excrete the NaCl.

PH2113 The Heart (17 decks)

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