CVR Ischaemic heart disease & hypoxia Flashcards
WHat is IHD?
the term given to heart problems caused by narrowed heart arteries that supply its muscle
signs of IHD
- angina (syncope, aching, radiation in arms, high or low BP)
- Heart rhythm problems (palpitations, heart murmurs, tachycardia, atrial fibrillation, S4, S3 gallop from non-compliant ventricle)
- general important symptoms (nausea, sweating, fatigue, shortness of breath diaphoresis, leg swelling)
what is the leading cause of death in the world?
IHD
where is IHD most prevalent?
eastern europe
who is IHD most prevalent amongst?
older people (65+)
who is IHD most prevalent amongst?
older people (65+)
risk factors types of IHD (2)
modifiable
non modifiable
non-modifiable risk factors types of IHD
age, gender. family history CVD. ethnicity. genetic evidence, previous history of CVD
modifiable risk factors types of IHD
high BP, cholesterol, smoking, blood sugar/diabetes/LVH, BMI, diet, stress, low socioeconomic state, alcohol, income, certain meds, social deprivation environment
causes of IHD
obstruction cause by atheroma. spasms, embolus
what is involved in artherosclerosis? (3)
What is the process called?
lipids,
macrophages
smooth muscle cells
-> process is called artherogenesis
how do smooth muscle cells interact with plaques?
proliferate and cover plaque. Contains the plaque (lumen of blood vessel reduced)
TGF B and T-reg cells and macrophages do what to fibrous cap of stable plaque?
stabilise and protect it
when does a plaque become vulnerable?
when the fibrous cap thins
when does a plaque become vulnerable?
when the fibrous cap thins
presentations of IHD (3)
- asymptomatic
- chronic stable angina (stable fixed plaque)
- unstable angina, non-ST elevation MI, ST elevation MI (unstable plaques)
how does an occlusion occur in IHD?
- direct contact with the flowing blood
- blood platelets adhere to it, fibrin deposited, RBC entrapped to form a clot
- clot grows until artery occlude
- can break away e.g. PE
what happens to collaterals in sudden event?
doubling by the second/third day
- achieve normal flow within 1 month
what happens to collaterals in chronic atherosclerotic patients??
- slow occlusion vessels can develop at the same time while the atherosclerosis become more severe-
- these collaterals can also get damaged
- sometimes hypoxic area is too large
soon stages after MI (2)
- small amount of collaterals open
- local blood vessels dilate and cause overfilling with stagnant blood,
muscle fibres use all remainign O2 -> bloof turns blue brown
later stages after MI
vessel wall permeability increases, fluid leak and local tissue oedematous
- cardiac muscle cells swell and no blood supply means they die within a few hours
causes of death after MI (4)
- decreased CO (systolic stretch from muscle death and cardiac shock)
- damming of blood in body’s venous system
- ventricular fibrillation
- rupture of infarcted area (Early little danger after few days infarcted area begin to degenerate heart walls become very thin stretched until finally rupture)
x
x
recovery after an acute MI
- when large area of ischemia:
- > some of centre dies
- > immediate surrounding can recover
can CO stay the same after MI?
cardiac resolve means it can
how to diagnose IHD?
clinical history, clinical examination, Lab tests, bio markers (b types natiuretic peptide)
ECG in stable angina
looks normal
ECG in unstable angina
NSTEM - ST depression, T wave inbversion
ECG in acute MI/STEMI
ST segment elevation
T wave inversion
what does transthoracic eco assess?
- left ventricular function
- wall motion abnormalities in the setting of ACS or AMI
- mechanical complications of AMI
best way to assess coronary arteries
coronary angiography
x
x
treatment - pharmacological
- HMG-CoA reductase inhibitors e.g. atorvastatin - bile acid sequestrants (increased fecal loss of cholesterol)
- calcium channel blockers
- ACE inhibitors (esp important for hypertension)
- beta blockers for angina to decrease demand of MI O2
- antianginal agent e.g. ranolazine by reducing myocardial cellular and Ca overload. Inhibition of the later Na current of the cardiac action potential
- platelet aggregation inhibitors
- nitrates
treatment - revascularisation therapies
- percutaneous coronary intervention involving stent placement
- CABG - vessel from another part of body for blood to bypass blocked artery (when not possible to put stents in)
causes of reduced blood flow to a region in IHD
- Atheroma
- Thrombosis
- Spasm
- Embolus
- Coronary ostial stenosis
- Coronary arteritis
causes of decreased O2 blood flow to myocardium (3)
- Anaemia
- Carboxyhaemoglobulinaemia
- Hypotension causing decreased coronary perfusion pressure
What triggers artherogenesis? (6)
Endothelial dysfunction
Mechanical sheer stresses (HTN)
Biochemical abnormalities (elevated and modified LDL, DM, elevated plasma homocysteine)
Immunological factors (free radicals from smoking)
Inflammation ( infection such as chlamydia, Helicobacter)
Genetic alteration
serum markers in patients with suspected acute cardiac events
- Troponins(I or T)
- Creatine kinasewith MB isozymes
- Lactate dehydrogenase and lactate dehydrogenase isozymes
- Serumaspartate aminotransferase
biomarkers for predicting death in IHD (5)
- B-type natriuretic peptide
- CRP
- Homocysteine
- Renin
- Urinary albumin-to-creatinine ratio
what is Transoesophageal echocardiography use for?
assessing possible aortic dissection in the setting of AMI.
what can Stress echocardiography be used to evaluate
hemodynamically significant stenoses in stable patients who are thought to have CAD.
procedure of coronary angiography
- Iodinated contrast agent is injected through a catheter placed at the ostium of the coronaries.
- The contrast agent is then visualized through radiographic fluoroscopic examination of the heart.
- Coronary angiography remains gold standard for detecting stenoses that may be revascularized through percutaneous or surgical intervention
What is coronary CT angiography an important tool in?
Detecting the presence and extent of CAD and independent predictors of significant coronary stenosis and other cardiovascular events
Pros of performing ultrasonography on the common and internal carotid arteries
- a noninvasive measure of arterial wall anatomy
- may be performed repeatedly and reliably in asymptomatic individuals.
what is the most widely applied technqiue for measuring coronary flow in humans
Doppler Velocity probes
- It helps evaluating whether normal blood flow has been restored after percutaneous transluminal coronary angioplasty (PTCA).
How does Doppler Velocity probes work?
Doppler guidewire measures phasic flow velocity patterns and tracks linearly with flow rates in small, straight coronary arteries.
Example of bile acid sequestrants
Cholestyramine (Questran, LoCholest, Prevalite)
how do Ca channel blockers work?
amlodipine (Norvasc) relaxes coronary smooth muscle and produces coronary vasodilation, which in turn improves myocardial oxygen delivery.
Amlodipine (Norvasc)
examples of ACE inhibitors
Captopril (Capoten), enalapril (Vasotec), and lisinopril (Zestril).
what does percutaneous coronary intervention involve?
Involves angiography and stent placement:
Common to treat stable CAD
Improves blood flow by placing a stent and compressing the plaque
What does CABG involve?
A vessel from another part of your body to create a graft that allows blood to flow around the blocked or narrowed coronary artery. This type of open-heart surgery is usually used only for people who have several narrowed coronary arteries.
Recommendations from WHO for reducing risk of CHD
- Take moderate physical activity for a total of 30 minutes on most days of the week. - Avoid tobacco use and exposure to environmental smoke; make plans to quit if you already smoke. - Choose a diet rich in fruits, vegetables and potassium, and avoid saturated fats and calorie-dense meals. - Maintain a normal body weight; if you are overweight, lose weight by increasing physical activity and reducing calorie intake. - Reduce stress at home and at work.
