CR Week 1 Flashcards
1) Define the term cardiac output. (1 mark)
Cardiac output = volume of blood pumped out per ventricle per minute.
(2) Aside from cardiac output, name the other major physiological factor that determines mean arterial pressure (MAP). (1 mark)
- Total peripheral resistance (TPR) (systemic vascular resistance, SVR)
[Note: CVP is usually at or near 0 mmHg and is largely ignored (except when pathological)].
(3) Blood pressure is usually measured indirectly by taking which two readings? State the units used. (3 marks)
1) Systolic pressure (top value), maximum (systolic – achieved during left ventricular contraction). (1 mark)
(2) Diastolic pressure (bottom value), minimum (diastolic – achieved during ventricular filling). (1 mark)
- in mmHg (the unit for measuring blood pressure). (1 mark)
For example: 125/90 mmHg.
(4) State two risk factors for hypertension that are mentioned in the scenario. (1 mark)
½ mark for each
- Family history
- Age - older you are, the more likely you are to get high blood pressure.
- Gender - men are more likely to get high blood pressure than women are.
- Smoking
- Being overweight
- Not doing enough exercise
(5) Describe two drugs that could be prescribed to the patient in the scenario to lower blood pressure. Briefly outline their mechanism of action. (4 marks)
1. ACE inhibitors (½ mark) - inhibit the actions of angiotensin-converting enzyme (ACE) and the production of angiotensin II (½ mark) to cause vasodilation (½ mark) – reduces total peripheral resistance (TPR) (½ mark).
2. Angiotensin II receptor blockers (½ mark) – These drugs selectively inhibit angiotensin II via competitive antagonism of the angiotensin II receptors (½ mark), to cause vasodilation (½ mark) – reduces total peripheral resistance (TPR) (½ mark).
3. Thiazides and related compounds (½ mark) – act to inhibit sodium reabsorption at the beginning of the distal convoluted tubule (½ mark) and hence cause diuresis (increase in water excretion) (½ mark) – note (not fully understood but) reduces blood volume/cardiac output in the short term (½ mark).
what is systolic and diastolic presure?
systolic pressure – the pressure when your heart pushes blood out
diastolic pressure – the pressure when your heart rests between beats
how do you calculate CO? [1]
how do you calculate BP? [1]
Cardiac output (L/min) = Stroke volume (L) x Heart rate (BPM)
Cardiac output x Peripheral resistance = BP
how do you calculate mean arterial presssure? [1]
Mean arterial pressure = Cardiac output x vascular resistance (how hard it is to pump blood through vascular). More fluid you have causes a higher BP.
define hypertension
Hypertension is persistently raised arterial blood pressure.
what are the following?
- Primary/ Essential hypertension?
- Malignant hypertension?
- Secondary hypertension?
- White-coat hypertension?
- Masked hypertension?
•Primary/ Essential hypertension: Abnormally high BP, not due to a chronic medical condition (~95% cases)
•Malignant hypertension: Rapid rise in BP, resulting in vascular damage
•Secondary hypertension: High BP secondary to a chronic condition (~5%)
•White-coat hypertension: High BP in clinic, Low/normal out of clinic
•Masked hypertension: Low/normal BP in clinic, high out of clinic
how do you measure BP? [2]
- Sphygmomanometer
- Ambulatory Blood Pressure: 24 hour period
which factors affect BP?
- Cardiac output: HR x Stroke volume
- Peripheral Vascular Resistance
- Volume of circulating blood
- Viscosity of blood
- Elasticity of vessel walls (compliance)
which hormones modulate BP in hormonal response to hypertension? [3]
which neutrotransmitter modualtes neuronal to hypertension? [1]
what is the effect of both of above?
Hormonal: Antidiuretic Hormone (ADH), Aldosterone, Angiotensin II
-Modulates: heart rate, inotropy, total peripheral resistance and bloodflow between tissue
Neuronal: Noradrenaline
- Modulates sodium and water retention, total peripheral resistance and bloodflow between tissue
what are risk factors for hypertension?
- Age — blood pressure tends to rise with advancing age.
- Sex — Up to about 65 years, women tend to have a lower blood pressure than men. Between 65 to 74 years of age, women tend to have a higher blood pressure.
- Ethnicity —Black African and Black Caribbean origin (more likely)
- Genetic factors —40% of variability in blood pressure may be explained by genetic factors.
- Social deprivation — people from the most deprived areas in England are 30% more likely to have hypertension than those from the least deprived.
- Lifestyle — smoking, excessive alcohol consumption, excess dietary salt, obesity, and lack of physical activity are associated with hypertension.
- Anxiety and emotional stress —increased adrenaline and cortisol levels.
what is hypertension a risk factor for? [2]
•NUMBER 1 RISK FACTOR FOR CARDIOVASCULAR DISEASE = Myocardial Infarction (MI), Stroke
why are eyes affected with hypertension?
-Hypertension = raised BP
-Raised pressure within brain (intracranially)
-Raised pressure or volume to retinal vessels
-Vessels within eye are small/delicate and fragile, especially susceptible to pressure changes.
- Haemorrhage manifests (dot and blot) as microbleeds can occur.
- Other factors can cause angiogenesis within the eye (such as VEGF),in diabetes mellitus = new vessel formation = vessel fragile = burst easily.
why undertake a urine test when have hypertension? - what are you checking for? [3]
- Proteinuria (protein in urine)?
- Haematuria (blood in urine) (gross vs fine)?
- Glycosuria (glucose in urine?!)
define stroke & the two types that occur
- Interruption to blood flow to part of brain, causing ischemia (insufficient blood flow)and hypoxia (insufficient oxygen)
- Generally caused by:
oInfarction (artery blockage)
oHaemorrhage (Rupture of an aneurysm)
explain how RAAS influences BP
what do hypertensive drugs do to RAAS?
-
Renin-Angiotensin-Aldosterone system (RAAS)
- - Most drugs aim to block RAAS
- - Kidney senses low BP and renin is released from the juxtaglomerular cells
- - Renin converts angiotensinogen to angiotensin I
- - ACE from the lungs converts angiotensin I to angiotensin II
- - Angiotensin II (extremely potent vasoconstrictor) stimulates aldosterone release resulting in increased Na+ and thus water reabsorption which leads to increased blood volume and thus blood pressure
-
- Thus angiotensin II increases peripheral resistance and inhibitors target this
2.
name two diseases that could cause 2ry hypertension [1]
Endocrine:
Primary aldosteronism (increasingly recognised as a major cause of hypertension, see notes )
Phaeochromocytoma
Cushing’s syndrome (see notes)
Acromegaly (see notes)
Renal
Renovascular disease (e.g. atheromatous, fibromuscular dysplasia)
Intrinsic renal disease (e.g. CKD, AKI, glomerulonephritis)
Drugs
Glucocorticoids
Oral contraceptives
SSRIs
NSAIDs
EPO
name 2 signs and 2 sypmtopms of hypertension [2]
Hypertension is typically asymptomatic. However, signs and symptoms may reflect underlying end-organ damage or a potential secondary cause.
Symptoms:
Palpitations
Angina
Headaches
Blurred vision
New neurology (e.g. limb weakness, paraesthesia)
Signs
New neurology (e.g. limb weakness, paraesthesia)
Retinopathy
Cardiomegaly
Arrhythmias
Proteinuria
describe how you conduct ambulatory BP monitoring
describe how you conduct home blood pressure monitoring
If clinic BP is 140/90 mmHg or higher, ABPM is used to confirm the diagnosis (except in Stage 3 hypertension, in which immediate treatment is initiated).
With ABPM, at least two measurements an hour are taken during the patient’s usual waking hours (e.g. 8 am - 10 pm). The average value of these measurements is used to confirm the diagnosis. Alternative strategies can be considered including doing a full 24-hour assessment that includes nocturnal readings.
Home blood pressure monitoring (HBPM) can be used. This involves taking two measurements a day (morning & evening) over a period of at least 4 days, ideally 7. At each recording, two consecutive measurements should be taken at least 1 minute apart when the person is seated. The readings on the first day are discarded and the average of the following readings are used to confirm a diagnosis of hypertension.
describe white coat hypertension
This refers to an elevated blood pressure above the normal range in a clinical setting (e.g. GP appointment, hospital outpatients). It is defined as a discrepancy of > 20/10 mmHg between clinic and average ABPM/HBPM
In white coat hypertension, blood pressure is thought to be artificially elevated due to the stress of being in a clinical settin
