Hypertension, Ischaemic Heart Disease and Cardiac Failure Flashcards
Where does hypertension occur
It can occur in either the systemic or pulmonary circulation however is more difficult to diagnose in the pulmonary circulation.
What is the formula for blood pressure
Blood pressure (BP) = cardiac output (CO) X peripheral resistance (PR)
What is the difference between primary and secondary hypertension
Primary/essential hypertension occurs on its own. Secondary hypertension occurs due to an underlying cause.
What is malignant hypertension
Malignant hypertension is when there is acute end organ damage as a result of hypertension.
What is hypertension
Sustained resting blood pressure above a certain level.
Above what value is blood pressure considered to be high in most instances
140/90 mmHg
What determines the severity of hypertension
Diastolic pressure
What is more dangerous acutely - increased systolic or diastolic pressure?
Systolic as this can lead to haemorrhage.
What are some secondary causes of hypertension
Renal disease (which can also be caused by hypertension), endocrine disease, drug treatment, coarctation of the aorta
What are the risk factors for primary hypertension
- Genetic Susceptibility
- High salt intake
- Chronic stress
- Abnormalities in the renin-angiotensin system which controls blood volume and blood pressure
- Obesity
- Diabetes
What is benign hypertension
Where there are slow changes in the vessels and heart resulting in chronic end-organ dysfunction (as opposed to rapid changes and acute end-organ dysfunction).
Which organs are susceptible to the end-organ effects of hypertension
The heart, the kidney, the brain, the vessels.
Why is the retina important in hypertension
The retina acts like a window into the blood vessel system.
What technique can be used to see end-organ damage as a result of hypertension
Retinoscopy
What are the end organ effects on the heart due to hypertension
Left ventricular hypertrophy, coronary artery atheroma, ischaemic heart disease and cardiac failure.
What are the complications of left ventricular hypertrophy
Fibrosis and arrhythmias
What are the end organ effects on the kidney due to hypertension
Nephrosclerosis, “drop-out” of nephrons due to vascular narrowing, proteinuria, chronic renal failure
How do you assess renal dysfunction
Check the urine.
What are the end organ effects on the brain due to hypertension
Aneurysm resulting in intracerebral haemorrhage causing stroke.
What vascular changes other than atheroma result from hypertension
Hyaline change and fibrinoid necrosis.
What can be seen in retinoscopy if benign hypertension is present
Nipping of blood vessels and enlargement in other areas
What can be seen in retinoscopy if malignant hypertension is present
Rupturing blood vessels and evidence of end organ damage.
What is ischaemic heart disease
When the blood supply to the heart is insufficient for its metabolic demands. This can be deficient supply, excessive demand or both.
What factors cause deficient supply of blood resulting in ischaemic heart disease
Coronary artery disease or reduced coronary artery perfusion as a result of shock or severe aortic valve stenosis.
What factors cause excessive demand resulting in ischaemic heart disease
- Pressure overload, e.g. hypertension or valve disease. Pressure overload occurs due to a tight valve.
- Volume overload, e.g. valve disease. Volume overload occurs due to a leaky valve.
What level of occlusion leads to ischaemia in coronary heart disease
More than 75% occlusion.
What is myocardial infarction
An area of necrosis of heart muscle resulting from reduction (usually sudden) in coronary blood supply.
What are the causes of myocardial infarction
Coronary artery thrombosis, haemorrhage into a coronary plaque, increase in demand for oxygen in the presence of ischaemia.
What are the clinical features of MI
Central “crushing” chest pain
What can be used in the diagnosis of MI
ECG changes and blood markers
What blood markers are tested for in MI
Enzymes such as creatine kinase and other proteins such as troponin. Troponin is used most often now as it is more sensitive to heart muscle changes.
How long after an MI are changes observable in the heart muscle
About 24 hours. Less than 18 hours after there will be no changes.
What are the macroscopic changes that occur between 24 and 48 hours after an MI
Pale, oedematous muscle
What are the microscopic changes that occur between 24 and 48 hours after an MI
Odema, neutrophil infiltration and necrosis of myocytes
What are the macroscopic changes that occur between 3 and 7 days after an MI
A yellow, rubbery centre with a haemorrhagic border
What are the microscopic changes that occur between 3 and 7 days after an MI
Obvious necrosis and inflammation. Early granulation tissue.
What are the macroscopic changes that occur between 1 and 3 weeks after an MI
The infarcted area is paler and thinner than the unaffected ventricle.
What are the microscopic changes that occur between 1 and 3 weeks after an MI
Granulation tissue then progressive fibrosis.
What are the macroscopic changes that occur between 3 and 6 weeks after MI
Silvery scar becoming tough and white
What are the microscopic changes that occur between 3 and 6 weeks after MI
Dense fibrosis
How can you identify which artery the occlusion occurred in
By the location of the infarct
Where will the infarct be situated if the right coronary artery is occluded
On the inferior surface. it can involve the posterior septum.
Where will the infarct be situated if the left coronary artery is obstructed
This is the artery of “sudden death”. The infarct will be anterior.
Where will the infarct be situated if the circumflex artery is obstructed
The infarct will be lateral.
What are the complications of acute myocardial infarction
Sudden death, dysrhythmias, persistent pain, angina, cardiac failure, mitral incompetence, pericarditis, cardiac rupture, mural thrombosis, ventricular aneurysm.
How does sudden death result from MI
The myocardial infarct can soften and rupture or ventricular fibrillation can occur.
How do dysrhythmias result from MI
Due to abnormal electrical activity.
How does persistent pain result from MI
Due to progressive necrosis
How does angina result from MI
Ischaemia of non-infarcted cardiac muscle.
How does cardiac failure result from MI
Due to ventricular dysfunction or dysrhythmias
How does mitral incompetence result from MI
Due to papillary muscle dysfunction or necrosis
How does pericarditis result from MI
The pericardium becomes inflamed which can cause sharp chest pain.
How does cardiac rupture result from MI
Due to weakening of the cardiac wall by necrosis.
How does mural thrombosis result from MI
Due to abnormal endothelial surface
How does ventricular aneurysm result from MI
Due to the stretching of newly formed scar tissue.
What is cardiac failure
Failure of the heart to pump sufficient blood to satisfy metabolic demands.
What is the effect on the kidneys of heart failure
Under perfusion of the kidney leading to fluid retention and increased blood volume.
What are the types of heart failure
Left heart failure, right heart failure, low output failure, high output failure, systolic failure, diastolic failure.
What is cor pulmonale
This is right heart failure as a result of pulmonary hypertension
What is acute heart failure
A rapid onset of symptoms often with a definable cause such as myocardial infarction.
What is chronic heart failure
A slow onset of symptoms associated with ischaemic or valvular disease.
What is congestive heart failure
Failure of both the right and left ventricles.
What can cause high output heart failure
Thyroid disease.
What can cause diastolic failure
The heart cannot relax properly. This can be due to TB.
What is the most common cause of heart failure
A combination of hypertension and ischaemic heart disease.
What are two examples of valvular heart disease
Bicuspid aortic valve and senile calcific stenosis.
What is bicuspid aortic valve
Some people are born with a bicuspid as opposed to tricuspid aortic valve. This can lead to calcific stenosis at a younger age.
What is senile calcific stenosis
Where there are lumps of calcification on the valve which stops it from opening or closing properly.
What is the most common type of ventricular failure
Left ventricular failure
What effect does left ventricular failure have on the pulmonary circulation
Pulmonary oedema and pulmonary hypertension
How does right heart failure result from left heart failure
Left heart failure causes pulmonary hypertension which puts back pressure on the right ventricle and causes right ventricular failure.
What are the clinical features of forward failure
Reduced perfusion of tissues. This is associated with advanced failure.
What are the clinical features of backward failure
This results from increased venous pressure. For left ventricular failure backward failure results in pulmonary oedema. For right ventricular failure backward failure results in hepatic congestion and ankle oedema.
What are the clinical features of left ventricular failure
- hypotension
- pulmonary oedema
- paroxysmal nocturnal dyspnoea (accumulation of fluid in the lungs at night meaning they wake up breathless)
- breathlessness of exertion
What are the clinical features of right ventricular failure
- ankle swelling
- hepatic congestion
