Ischaemic Heart Disease Flashcards
What is ischaemia?
- inadequate blood flow and oxygen supply to maintain metabolism
What is cardiac ischaemia?
- inadequate blood flow and oxygen supply to the heart muscle
- Synonymous with ‘Coronary artery disease’
Where is predominantly affected in the heart by ischaemia?
- coronary arteries
- sometime caused by exertion
What is atherosclerosis?
- build up of plaque in the arteries
- made up of fat, cholesterol, calcium, and other substances found in the blood
Ischaemic heart disease is made up of a group clinical syndromes that occur due atherosclerosis. What are the 3 most common clinical syndromes of ischaemic heart disease?
1 - angina
2 - myocardiac infarction
3 - heart failure
- arrthymias and mitral valve dysfunction not as common
What does incidence and prevelance mean?
- incidence = new case of a disease (ACUTE)
- prevelance = number of people living with disease (CHRONIC)
How can incidence and prevelance be applied to ischaemic heart disease (IHD)?
- IHD is a chronic condition (prevelence)
- IHD presents with acute symptoms (incidence)
What is the leading cause of mortality, if you do not include cancer?
- ischaemic heart disease
Roughly how many people a year die from ischaemic heart disease?
- 64,000 people
- mean more likely
- associated with deprivation
Incidence and prevelence of ischaemic heart disease both increase with age, but why does the prevelence decrease around the 90s?
- patients die, so appears prevelence decreases
What is angina?
- chest pain caused by reduced blood flow to the heart
What are the common description of patients pain in angina?
- dull
- tight
- squeezing pain
- heavy
In angina is pain localised well?
- no
- felt across the chest
- felt in arms (left), neck and jaw
When are 3 common day to day activities can mean that angina is more likley to occur?
- upon exertion (increased demand on cardiac tissue)
- cold temperatures (blood vessels vasoconstrict)
- following a meal (blood diverted to GIT)
Why is angina described as demand ischemia?
- generally occurs due to increased demand
- reduced blood can flow so when demand increases pain is felt
What is the difference between angina and myocardial infarction?
- angina = narrowing of arteries
- myocardial infarction = complete blockage of arteries
What is visceral pain, also described as referred?
- pain caused by inner organs of the body
- cardiac pain is visceral pain
What aspects of the nervous system and spine does cardiac pain come from?
- autonomic (sympathetic and para-sympathetic)
- generally carried by afferent nerves
- T1-5
- C5-6
- C7-8
What is a myocardial infarction?
- complete blockage of artery
In a myocardial infarction, what pain do patients experience?
- severe and persistent chest pain
- does not go away
- referred and poorly localised
In a myocardial infarction, in addition to pain what are other tell tail signs patients can experience?
- nausea
- fever
- breathlessness
- malaise (general feeling of discomfort)
Is a myocardial infarction caused by increased demand of blood?
- no
- it is just a complete block
What generally causes a myocardial infaction that has been in the arteries for some time?
- atherosclerotic plaque has ruptured
- generally the fibrous cap ruptures
- thrombotic contents initiate blood clot that blocks artery
Once a fibrous cap becomes a vulnerable plaque it is highly likley to rupture. What leaks out of the plaque that is highly thrombogenic?
- collagen triggers platelet activation forming a blood clot
- lipids
Once collagen and lipids have leaked out of ruptured plaque, what can happen next?
- collagen and lipids are highly thrombogenic
- primary hemostasis is activated and platelets form a loose clot
Once collagen and lipids have leaked out of ruptured plaque, and activated platelets, what forms in the artery?
- platelet thrombus
Once collagen and lipids have leaked out of ruptured plaque, and activated platelets forming a platelet thrombus that is extensive, what can this switch on?
- coagulation cascade
- a more stable blood clot is formed
Once collagen and lipids have leaked out of the ruptured plaque, and activated platelets forming a platelet thrombus that is extensive, forming a blood clot, this can do what?
- if complete block it can cause an ST elevation and major MI
- partial = pain
Once a blood clot has formed in the coronary arteries, this can cause an embolism. What can happen then?
- part of the embolism can break away
- form an embolism in coronary tree
In the ischaemic cascade what is the first sign of ischaemia?
- hypoperfusion
- reduced blood flow
In the ischaemic cascade what follows hypoperfusion?
- metabolic disturbances
- ⬇️ O2 and ⬆️ CO2 cannot be removed
- Na+ pump becomes dysfunctional
- can cause arrthymias
In the ischaemic cascade, following hypoperfusion, metabolic distrubances, what occurs next?
- diastolic dysfunction
- systolic dysfunction
- heart beats irreguarly
In the ischaemic cascade, following hypoperfusion, metabolic distrubances, diastolic and systolic distrubances, what can these changes be detected with and present with in patients?
- ECG
- arrthymias
- chest pain
In the ischaemic cascade, following hypoperfusion, metabolic distrubances, diastolic and systolic distrubances, ECG changes and a patient with chest pain, what does this all lead to?
- myocyte necrosis
Once the ischaemic cascade has been triggered, how long can it take for myocytes necrosis to occur?
- 15 minutes
In addition to angina and myocardiac infarction, what is the 3rd common clinical syndrome of ischaemic heart disease?
- heart failure
- inability to maintain cardiac output
In heart faiilure fluid retention is common. What are the common clinical presentations of fluid retention?
- fatigue to lack of cardiac output
- leg swelling
- breathlessness (cough)
- worse when lying flat
- waking in the night
In heart failure why is breathing more difficult to breathe?
- pressure changes in the heart causes pulmonary oedema
- reduced perfusion takes place due to fluid build up
- makes breathing more difficult
Heart failure has lots of causes, but what is the most common cause?
- ischaemic heart disease
What is silent ischaemia?
- patients who have ischaemia with no symptoms
Why is silent ischaemia dangerous?
- patients can drop dead with no warning
What are the 3 principles for managing ischaemic disease?
- lifestyle change
- risk factor management
- anti-thrombotic therapy
Hypertension is a risk factor for ischaemic heart disease. What medication can patients be given to help this?
- ACE inhibitor = ramirpil
Hyperlipiaemia is a risk factor for ischaemic heart disease. What medication can patients be given to help this?
- statins = atorvastatin
Diabetes is a risk factor for ischaemic heart disease. What medication can patients be given to help this?
- metformin or insulin
Patients with ischaemic heart disease (IHD) or at risk of IHD are more likley to form platelet thrombi. What anti-platelet medications can be prescribed to reduce this risk?
- aspirin (most common) = inhibits COX-1
- clopidogral = inhibits Py212 ADP receptor
Patients with ischaemic heart disease (IHD) or at risk of IHD are more likley to have activation of the coagulation cascade due to the formation of platelet thrombi. In patients with a suspected thrombi following platelet clot formation patients are given anti-coagulation medications, which drugs are these?
- heparin
- specifically low molecular weight heparin
In patients with angina drugs that act directly on the heart, specifically Beta blockers. Which drugs are these?
- B1 blocker = Bisoprolol
- ⬇️ inotrophic force
- ⬇️ HR (through vagal tone)
In addition to Beta blockers, other medications can be given to help patients with angina. What other drugs may a patient with angina be prescribed?
- Ca2+ channel antagonist
- D.A.V = Diltiazem, Amolodapine, Varapamil
- dilate coronary arteries and lower BP
What drug can be given to patients with angina at the time of an angina attack?
- glyceryl trinitrate (GTN)
- dilates arteries
In patients prescribed GTN, what is a common effect if people are not sat down?
- drop in BP, makes people collapse
The two major coronary arteries coming from the main left coronary artery are the left circumflex and left anterior descending artery. How much blood do these arteries provide to the heart?
- left circumflex = 20-30%
- left anterior descending artery - 45%
The major coronary arteries coming from the main right coronary artery are the right coronary artery. How much blood does this artery provide to the heart?
- 25-35%
Out of the left anterior descencing artery, left circumflex artery and the right coronary artery, which can be most dangerous if blocked?
- left anterior descencing artery
What is a coronary bypass graft, commonly referred to as CABG?
- open heart surgery
- heart placed on bypass machine
- new artery is used to bypass the bloackage
Commonly internal mammary arteries (sometimes radial arteries) is detached from the proximal end and re-attached to the coronary circulation. Why is an artery better for this than a vein?
- arteires can withstand high pressures better and last longer
- sphenous vein (in leg) can be used as well
In addition to CABG, a method called Percutaneous Coronary Intervention, also called stenting and angioplasty, has been developed that is less invasive. What is this?
- catheter is inserted intor coronary arteries
- a wire is fed through with a balloon
- balloon is inflated and stent deployed to open artery
Is Percutaneous Coronary Intervention, also called stenting and angioplasty, a dangerous and long procedure?
- no, performed under local anastetic
- patients home next day and back to normal in 1 week
If Percutaneous Coronary Intervention, also called stenting and angioplasty is so good, why are CABGs performed at all?
- CABG can bypass large parts of blocked artery
- Percutaneous Coronary Intervention only fixes a small part of coronary
Does Percutaneous Coronary Intervention or CABG have better prognosis?
- CABG
In an acute myocardial infarct (MI) necrosis is detectable within 15 minutes. Where the MI is located, do all cells die equally?
- no cells closer to subendothelial are affected more
- collateral blood vessels provide protection
- even after 12 hours tissue can be saved
Although stenting does not appear to have any significant impact on prognosis in coronary artery elective surgery, does it have any impact on acute myocardial infarction?
- yes
- enourmous effect on prognosis
- no treatment = 10% mortality
- stenting with ballooning = <1% mortality
