Hypertension Flashcards
Define cardiovascular disease (CVDs)
A group of disorders affecting the heart and blood vessels
What is coronary heart disease (CAD) and what causes it
Condition where the heart is deprived of oxygen due to reduced blood supply due to blockage of the arteries supplying blood to the heart
What is CAD also known as
Ischemic heart disease (IHD)
What conditions are included in CAD
Stable angina
Angina
ACS
Myocardial infarction
Sudden cardiac death
What are the presentations of stable angina
Chest discomfort and symptoms precipitated by activity with minimal or no symptoms at rest
What is ACS
Syndrome where there is a lack of blood flow to the heart to supply the needs of myocytes often due to a blockage of a coronary artery. This may cause parts of the heart to not function properly or even die
Types of ACS
Unstable angina
NSTEMI
STEMI
How does angina pain develop?
When there is an increased blood supply demand in the setting of stable atherosclerosis plague but the vessel is unable to dilate enough to allow adequate blood flow to meet the myocardial demand
What occurs in unstable angina?
Plague ruptured and a thrombus forms around the ruptured plague causing partial occlusion of the vessel resulting in angina pain
What occurs in NSTEMI
Plague ruptures and thrombus formations causes partial occlusion to the vessel resulting in injury and infarct to the subendocardial myocardium
What occurs in STEMI
Complete occlusion of the blood vessel resulting in transmural injury and infarct to the myocardium
What is atherosclerosis
Development of bulging fatty deposits called plagues j in n large arteries leading to reduced blood flow or blockage of an artery if plague breaks open and clotting occurs
What is dyslipidaemia
Presence of altered levels of lipoproteins in the blood
What lipoprotein levels are associated with artheroslerosis
Increased levels of low density lipoprotein particles and decreased levels of high density lipoprotein particles
Define ischaemic stroke
Condition where blockage from thrombus or a clot in blood vessel causes lack of adequate blood flow into the brain via cerebral arteries resulting in ischemia, hypoxia and neuronal death
Define haemorrhagic stroke
Rupturing of vessels and blood leaks out causing large thrombus within the area causing pressure on the brain leading to damage
Common mechanism of heart failure
Reduction of stroke volume which causes reduction in cardiac output
What is stroke volume
volume of blood ejected with each contraction of the heart
What are the 2 problems that result in heart failure
Contractile problem
Filling problem
What occurs in contractile problem heart failure
Damaged myocytes cant contract as hard as they should
What occurs in filling problem heart failure
Ventricles become stiff and do not receive enough blood
Heart failure classifications
Heart failure with reduced Ejection Fraction (HFrEF)
Heart failure with preserved Ejection Fraction (HFpEF)
What does Ejection Fraction measure
How much blood the left ventricle pumps out with each contraction
What problem occurs in HFrEF
Contractile problem - the damaged myocytes cannot contract as hard
What problem occurs in HFpEF
Filling problem - the ventricles are stiff and do not receive enough blood
Why do patients with heart failure experience fatigue
they have reduced blood flow to tissues such as skeletal muscles due to low stroke volume
Why can oedema occur in patients with heart failure
Blood is not being cleared out of the ventricles efficiently causing it to build up in veins and capillaries therefore water will leak out to surrounding tissue and increases tissue fluid.
What is arrhythmia
irregular or altered rate of action potential movement throughout the heart causing disturbance to the electrical activity in the heart
Common cause of arrhythmia
ischaemia and death of myocytes causing damage to an area and deposition of collagen that impairs the normal spread of action potentials throughout the heart
Types of arrthymia
Atrial fibrillation
Define hypertension
Sustained elevation in systolic blood pressure of greater or equal to 140 mmHg and or diastolic blood pressure of greater than or equal to 90mmHg in people not taking antihypertensive medications
What are symptoms in uncomplicated primary hypertension
asymptomatic although some patients with very high blood pressure may feel headache
What does the term secondary hypertension describe
high blood pressure that is a result of underlying diseases or use of medicines and substances
3 ways hypertension is diagnosed
Doctors office
Ambulatory blood pressure monitor
home blood pressure monitor
How to receive a diagnosis of hypertension
Patient’s blood pressure must be taken 3 times on one occasion, discard first reading and average second and third
High readings on different occasions 1-2 weeks apart
What does systolic pressure measure
pressure in arteries when heart beats
What does diastolic pressure measure
pressure in arteries when heart rests between beats
What is blood pressure measured as
The force exerted by the blood against the inner walls of blood vessels
What is the blood pressure equation
BP= Cardiac output X total peripheral resistance - central venous pressure
What is the cardiac output equation
CO= Heart rate X Stroke Volume
Why do we need blood pressure
Blood flow to organs relies on the pressure gradient between arteries and veins so if blood pressure is low there is not enough pressure to drive blood to organs
What is mean arterial pressure
Estimate of the average pressure during the cycle
According to the BP equation, what can cause blood pressure to rise
Cardiac output and total peripheral resistance can cause bp to rise
What can cause cardiac output to rise
Heart rate
Stroke Volume
CO= HR x SV
What causes stroke volume to rise
increased blood volume
increased contractility
What causes Total Peripheral resistance
net vasoconstriction- more arterioles constrict than dilate
sympathetic nerve activation- more arterioles constrict when sympathetic nerves activate
Vasoconstriction means contraction of vascular smooth muscle cells –> arteriole diameter reduction –> increase resistance –> increases TPR and therefore increases BP
How does sympathetic nerve activation cause increase BP
More arterioles have a adrenoceptors causing vasoconstriction, e.g. GI tract than there are arterioles that have b2 adrenoceptors, e.g. skeletal muscle, which cause vasodilation
Factors that causes BP to rise
Sex
Environmental- stress
Genetic- elevated angiotenin II levels, elevated aldosterone levels
CNS- sympathetic activation
Cardiac- cardiac output
Renal- sodium retention
Gastrointestinal- obesity, micronutrients, alcohol
Endocrine- insulin, aldosterone
Age
Endothelium- nitric oxide
What is a hypertensive emergency
blood pressure is so high patients have start to have symptoms such as headache, chest pain, nausea, vomiting
Do patients notice they have high BP
no, most patients don’t notice they have high BP for years
What can hypertension result in
morbidity and mortality
What changes occur in the heart in hypertension
Cardiac Remodelling- changes to the heart structure and function
Macro and microvascular effects- changes to large and small blood vessel structure and function
What does changes in heart structure and function lead to
Increase risk of:
Stroke
Heart failure
Myocardial infarction
kidney failure
What are the types of load on the heart
Preload (wall stress): load on the myocyte prior to contraction, how stretched it is at the end of the filling period
Afterload: pressure that the heart must work against in order to eject blood.
What causes greater afterload
High total peripheral resistance causing higher arterial pressure means the heart must exert a greater force to eject the same amount of blood
Stages of cardiac cycle
- ventricular filling
- ventricular contraction
- ventricular ejection
- ventricular relaxation
What does remodelling refer to
Changes in the structure of the heart that can affect the function
How does hypertension affect load on the heart
Hypertension causes increased load on the heart
How does the heart respond to increased load on the heart
Increases the size and strength of myocytes (hypertrophy)
What signalling molecules are released under conditions of higher mechanical load on the heart
angiotensin II and antrial natriuretic peptide are released
What does angiotensin II act on and to cause what
AT1 receptors on
Cardiomyocytes: cardiomyocyte enlargement resulting in hypertrophy
Vascular smooth muscle cells: resulting in hypertrophy
Fibroblasts in between cardiac or vascular smooth muscle cells: collagen deposition
What happens to the heart in hypertrophy and fibrosis
Heart stiffens causing decreased compliance, reducing efficiency of blood filling into the ventricles
