Extra Cardio Flashcards
Where are common places for atherosclerosis to develop?
- circumflex artery
- Left anterior descending
- right coronary arteries
Why is older age a risk factor for atherosclerosis?
As the body ages the risk for atherosclerosis increases and genetic or lifestyle factors cause plaque to gradually build in the arteries
What is claudication?
Claudication is pain caused by too little blood flow to muscles during exercise
Why is tobacco smoking a risk factor for atherosclerosis?
Tobacco leads to endothelium erosion of the arteries, which then means that lipids can get in and speed up the process.
Why is high levels of serum Cholesterol and obesity risk factors for atherosclerosis?
High levels of LDL’S means more will be deposited in the periphery.
Obesity means there is more pericardial fat and thus increase in inflammation.
Why is diabetes a risk factor for atherosclerosis?
Hyperglycaemia damages the endothelium and also magnifies the effect of other risk factors such as raised cholesterol levels, blood pressure, smoking ext.
Why is hypertension risk factor for atherosclerosis?
Mechanical stimulus to endothelial layer, weakens it.
Why is family history a risk factor for atherosclerosis?
It is a polygenic disease and some of the other risk factors also have a genetic part to them.
- ANRIL expression is associated with atherosclerosis risk at chromosome 9p21
- The ACE enzyme gene contains a insertion/deletion polymorphism, the DD genotype of which has been associated with a predisposition to CAD and MI
What are some other risk factors of atherosclerosis?
1) Male gender
2) Sedentary lifestyle
3) Psychosocial factors (type A personality)
4) Over consumption of alcohol
5) High levels of coagulation factor VII
Why is the focal distribution of an atherosclerosis along the artery length?
Changes in flow/turbulence e.g. at a bifurcation cause the artery to alter endothelial cell pattern. Wall thickness is also changed leading to neointima
What is neointima?
A new or thickened layer of arterial intima formed especially on a prosthesis or in atherosclerosis by migration and proliferation of cells from the media.
How can atherosclerosis lead to angina and thrombus formation?
Eventually the plaque will either occlude the vessel lumen resulting in restriction of blood flow (ANGINA).
or the plaque may rupture (THROMBUS FORMATION).
What initiates atherosclerosis formation?
Injury to the endothelium through smoking, cholesterols, BP, bacterial/viral infection… which leads to endothelial dysfunction(the vessel wall becomes sticky).
Once initiated chemoattractants are released from the endothelium at the site of injury to attract leukocytes which then accumulate and migrate into the vessel wall. When chemoattractants released a concentration gradient is produced.
What are the main cytokines involved in atherosclerosis formation?
IL-1 (MAIN) IL-6 IL-8 IFN-GAMMA C-REACTIVE PROTEIN
What other molecules are involved in leukocyte recruitment to the vessel wall?
Selectins, integrins and chemoattractants.
What do the fatty streaks consist of?
Aggregations of lipid-laden macrophages and t-lymphocytes within the intimal layer of the vessel wall.
What are foam cells?
Macrophages that have taken up lots of lipids
Progression of atherosclerosis: what are constituents of intermediate lesions?
- Foam cells.
- Vascular smooth muscle cells.
- T lymphocytes.
- Platelet adhesion and aggregation.
- Extracellular lipid pools.
Progression of atherosclerosis: what are the constituents of fibrous plaques?
The fibrous cap is made of extracellular matrix proteins including collagen (strength) and elastin (flexibility) laid down by smooth muscle cells that overly lipid core and necrotic debris. Maybe calcified.
- Smooth muscle cells.
- Macrophages.
- Foam cells.
- T lymphocytes.
- Plaque is filled with fibrin
Fibrous plaques can impede blood flow and are prone to rupture.
Progression of atherosclerosis: why might plaque rupture occur?
Fibrous plaques are constantly growing and receding. The fibrous cap has to be resorbed and redeposited in order to be maintained. If balance shifted in favour of inflammatory conditions due to increased enzyme activity), the cap becomes weak and the plaque ruptures. Basement membrane, collagen and necrotic tissue exposure as well as haemorrhage of the vessel within the plaque. Thrombus formation and vessel occlusion.
Progression of atherosclerosis: why might plaque erosion occur?
The fibrous cap may be disrupted by collagen leading to thrombosis. The difference to a plaque rupture is that thrombosis is triggered by collagen and not tissue factors. A platelet-rich clot may overlie the luminal surface and there may be a prominent lipid core.
What is restenosis?
Restenosis means that a section of the blocked artery that was opened up with angioplasty or a stent has become narrowed again. This is normally due to the response of the vascular tissue to the injury caused by coronary angioplasty
What are stents made from? why?
Made from stainless steel as they are able to withstand the pressure.
What drugs could be put on the stent? why do we do this?
Sirolimus. It stops the proliferation of smooth muscle cells from the media layer into the plaque.
What is the normal systolic ejection fraction?
60% of what’s in the heart’s chambers
What is cardiac failure? What can it lead to?
Failure to transport blood out of the heart. If severe can lead to cardiogenic shock. Cardiogenic shock is a condition in which your heart suddenly can’t pump enough blood to meet your body’s needs. The condition is most often caused by a severe heart attack, but not everyone who has a heart attack has a cardiogenic shock.
Describe the Frank-Starling mechanism
Ventricular contraction becomes more forceful as the cardiac muscle cells are stretched. By increasing the volume of blood in the ventricle at rest, the cardiac muscle is stretched, causing an increase in the force of contraction which ejects more blood and increases the stroke volume.
How does venous return affect stroke volume?
If you increase venous return to the heart, you increase the ventricular filling and filling pressure of the ventricle and therefore preload. Because preload is increased by Frank Starling’s mechanism (sarcomere length increased so stronger contraction) the stroke volume also increases.
What is on the X and Y axis of Frank Starling’s graph?
x= ventricular end-diastolic volume y= ventricular performance
What is preload? 2 definitions
1) The amount of sarcomere stretch experienced by cardiomyocytes at the end of ventricular filling during diastole. (heart getting ready for the next big push)
2) Volume of blood in the ventricles at the end of diastole (LVEDP-end-diastolic pressure).
In what conditions does preload increase?
1) Hypovolemia
2) Regurgitation of cardiac valves
3) Heart failure
What is after-load?
a.k.a systemic vascular resistance
Is the amount of resistance the heart must overcome to open the aortic valve and push blood volume into the systemic circulation.
What is the effect of preload on stroke volume?
Increased preload increases stroke volume, whereas decreased preload decreases stroke volume by altering the force of contraction of the cardiac muscle.
What is the effect of afterload on stroke volume?
Increasing the afterload decreases the velocity of fibre shortening. Because the period of time available for ejection is finite( around 200msec), a decrease in fibre shortening velocity reduces the rate of volume ejection so more blood is left within the ventricle at the end of systole. This means increased afterload means increased stroke volume and LVEDP.
What is the effect of Inotropy (cardiac contractility) on SV and LVEDP?
Decreased inotropy leads to decreased SV and increased LVEDP. When the heart muscle contracts, all muscle fibres are activated so the only way to control the force are inotropy and preload.
Why does the LVEDP fall when SV increase?
If the contractility (inotropy) increases there is more blood pumped out so the SV increases, so there is less residual blood after ejection so EDV decreases and therefore the ventricular filling has decreased so the pressure here is also decreased.
In what kind of people would you find physiological hypertrophy?
1) Athletes
2) Pregnant women (to cope with the increasing demands for pregnancy)
3) Pathological problem
Embryology of the heart
1) Heart derives from the mesodermal germ layer.
2) Heart is initially one tube until week 5, then it divided by the intraventricular and intra-atrial septa from endocardial cushions.
3) The muscular intra-ventricular septum grows upwards from the apex of the heart producing 4 chambers and allowing valve development.
The mesoderm differentiates into these. What does the mesothelium, endothelium and myocardium form?
MESOTHELIUM: pericardium
ENDOTHELIUM: endocardium, lymphatics and blood vessels
MYOCARDIUM: myocardium
What has acute rheumatic fever to do with heart disease?
It is a Group A B-haemolytic streptococcus infection, which usually affects the upper respiratory tract but has a cross-reaction with heart cells. It is a major cause of heart disease in the developing world as it produces localised inflammation and subsequent scarring fibrosis.
What is myocarditis and give 5 causes for it?
The inflammation of the myocardium usually associated with muscle cell necrosis and degeneration.
Causes:
- Viruses(Coxsackie, Adeno, Influenza, COVID)
- Sarcoid
- Cross reaction of antibodies against myocardial tissue.
What is cardiac myxoma?
Commonest primary heart tumour
What is Vasculitis? What are the complications?
Inflammation of the blood vessels. It may be a primary condition or secondary to other diseases.
Inflammed vessels leads to damaged walls and lumen narrowing this means reduced blood flow = ischemia and distal necrosis.
What are the causes of Vasculitis?
1) direct attack on vessels by antibodies
2) deposition of immune complexes that then trigger an immune response
3) cell-mediated immunity
4) viral infection (hep c, b)
Granulomatus arteritis / temporal arteritis
- what arteries affected?
- symptoms and signs
- complications
- treatment
- Inflammation of mainly temporal arteries.
- Present with scalp tenderness (hurts when brushing) and headaches, sudden bilateral vision loss.
- Blindness if arteries of the eye affected.
- Treatment is prednisolone 60mg (steroid)
What is an aneurysm?
An aneurysm is defined if there is a permanent dilatation of the artery to TWICE the normal diameter. The normal diameter of the aorta is around 2cm, however, this increases with age.
What are “true” aneurysms?
What are some arteries that are more frequently involved?
Abnormal dilatations that involve ALL LAYERS of the arterial wall.
Arteries most frequently involved are:
- Abdominal aorta (most common)
- Illiac, popliteal and femoral arteries
-Thoracic aorta
What are “false” aneurysms?
What the causes of it?
They are also known as pseudoaneurysms. This involves the collection of blood in THE OUTER LAYER ONLY (ADVENTITIA) which then communicates with the lumen.
They can occur:
- after injury to the artery e.g. trauma from a femoral artery puncture.
- after cardiac catherisation
What are “false” aneurysms?
What the causes of it?
They are also known as pseudoaneurysms. This involves the collection of blood in THE OUTER LAYER ONLY (ADVENTITIA) which then communicates with the lumen.
They can occur:
- after injury to the artery e.g. trauma from a femoral artery puncture.
- after cardiac catherisation
What causes aneurysms?
1) Atherosclerotic disease
2) High blood pressure
3) Connective tissue disorders (Marfans)
What are saccular aneurysms?
- Saccular aneurysms bulge on one side
- “Berry” aneurysms because they look like berries
- The most common type of brain aneurysm.
- Saccular aneurysms have a “neck” that connects the aneurysm to its main (“parent”) artery and a larger, rounded area called the dome.
- They bulge on only one side of the artery wall.
What are fusiform aneurysms?
The more common fusiform-shaped aneurysm bulges or balloons out on all sides of the blood vessel. Most AAAs
What are dissecting aneurysms?
An aneurysm in which the wall of an artery rips (dissects) longitudinally. This occurs because bleeding into the weakened wall splits the wall. Dissecting aneurysms tend to affect the thoracic aorta. They are a particular danger in Marfan syndrome.
What is an abdominal aortic aneurysm?
An abdominal aortic aneurysm is a bulge in the main blood vessel running from your heart to your tummy.
COVER UP NOTES SHEET AND ANSWER
Pathophysiology of AAA
- Degradation of the elastic lamellae resulting in leukocyte infiltrate causing enhanced proteolysis and smooth muscle cell loss.
- Dilatation affects all three layers of the vascular tunic. if not it is a false aneurysm.
Haemoptysis
Coughing up blood
Pathophysiology of TAAs
- Involves inflammation, proteolysis and reduced survival of smooth muscle cells in the aortic wall
- Once the aorta reaches a crucial diameter (around 6cm in ascending and 7cm in descending) it loses all distensibility so that a rise in BP to around 200mmHg can exceed the arterial wall strength and may trigger dissection or rupture.
Valvular diseases
see
What is the mitral valve?
Mitral valve is on the left side and is also known as the tricuspid valve, it separates the left atrium from the left ventricle. It has two cusps.
What is supra valvular aortic stenosis?
- ABOVE VALVE
- Congenital fibrous diaphragm above the aortic valve
What is sub valvular aortic stenosis?
- BELOW VALVE
- Congenital condition in which a fibrous ridge or diaphragm is situated immediately below the aortic valve.
Aortic valve
WHERE?
WHAT?
DESCRIBE
The aortic valve is located on the left side of the heart and separates the left ventricle from the aorta.
The aortic valve has 3 cusps.
It is one of the semilunar valves.
Describe 3 main causes of Aortic stenosis
- Congenital bicuspid valve.
The valve has 2 instead of 3 cusps. This is the most common congenital heart disease. - Acquired e.g. age-related degenerative calcification 3. Rheumatic heart disease.
Rare due to eradication.
Describe the pathophysiology of aortic stenosis.
- Aortic orifice is restricted e.g. by calcific deposits.
- So there is an obstruction to left ventricle emptying.
- So there is a pressure gradient between the LV and the aorta. Resulting in an increased afterload
- LV function is initially maintained due to compensatory hypertrophy.
- Obstruction more severe during exercise (more cardiac output needed), but this cannot happen bc of stenosis so leads to symptoms.
- Relative ischemia of the LV myocardium since hypotrophy results in increased blood demand.
- Over time this compensatory mechanism becomes exhausted = LV failure.
Why is there a prominent 4th heart sound in aortic stenosis?
Due to LV hypertrophy
Is the apex beat displaced in aortic stenosis?
No, as hypertrophy doesn’t produce any noticeable cardiomegaly. A systolic thrill may be felt in the aortic area.
What is TAVI?
Transcutaneous aortic valve implantation
- minimally invasive
- pass catheter up the aorta then inflate balloon across the narrowed valve which will crack the calcification
- pass another catheter which leaves a stent with a valve= new valve
How can rheumatic fever lead to mitral valve stenosis?
- Inflammation due to rheumatic fever leads to commissural fusion and a reduction in mitral valve orifice area, causing the characteristic doming pattern seen on echo.
- over many years, this can progress to vale thickening, cusp fusion, calcium deposition, a severely narrowed valve orifice and progressive immobility of the valve cusps.
Describe the pathophysiology of mitral stenosis.
- Obstruction of flow from LA to LV so to compensate for CO the LA pressure increases > LA hypertrophy and LA dilation -> pulmonary venous, pulmonary arterial and right heart pressure increase> pulmonary congestion.
- Increased trans-mitral pressures -> LA enlargement and AF and pulmonary oedma.
- Pulmonary venous hypertension causes RHF symptoms.
Why do you dyspnoea in mitral valve stenosis?
Left atrial dilation resulting in pulmonary congestion( reduce emptying), which is worse with exercise, fever, tachycardia and pregnancy.
Why do you get haemoptysis in mitral valve stenosis?
Rupture of bronchial vessels due to elevated pulmonary pressure.
Why do you get right heart failure in mitral valve stenosis?
Due to the development of pulmonary hypertension. This also is the reason why you get the “a” wave in jugular venous pulsations.
Why do you get AF in mitral valve stenosis?
Due to atrium dilatation giving rise to palpitations. this can then lead to systemic emboli.
Where is the diastolic murmur in mitral valve stenosis heard prominently?
The apex of heart when patient lying on the left side in held expiration.,
Why do you get a loud opening S1 snap-in mitral valve stenosis?
Due to abrupt halt in leaflet motion in early diastole after rapid initial opening. The more severe the stenosis, the longer the diastolic murmur and the closer the opening snap is to the second heart sound.
Describe the pathophysiology of aortic regurgitation.
1) AR is reflux of blood from the aorta through the aortic valve into the left ventricle during diastole.
2) If the CO is to be maintained then the total volume of blood pumped into the aorta must increase> LV size increase»LV dilatation and hypertrophy
3) Progressive dilatation leads to heart failure
4) The remaining blood in the root of the aorta supplies the coronary arteries via the coronary sinus during diastole. Regurgitation causes diastolic BP to fall so the coronary perfusion decreases. Due to the larger ventricular size which is mechanically less efficient and needs more oxygen, which is not able to perfuse properly»> ischemia and heart failure.
COMBINED PRESSURE AND VOLUME OVERLOAD = HF
What is a symptom?
A symptom is a manifestation of disease apparant to the patient himself.
What is a sign?
A sign is a manifestation of the disease that the physician perceives
In Aortic Regurgitation what is the Austin flint murmur a sign of? What is it?
Austin Flint murmur is a low-pitched rumbling heart murmur which is best heard at the cardiac apex. It is caused due to the downward eject of the aortic regurgitation murmur pressing on the mitral valve. Severe AR.