Week 8 Cardiovascular 1 Flashcards
Define Ischaemic heart disease.
Inadequate blood supply to the myocardium
What causes ischaemic heart disease?
Most comminly due to reduced coronary blood flow, almost always due to atheroma +/- thrombus.
Less common cause are due to amyloid accumulation or due to surgical problems
what additional complications can occur with ischeamic heart disease?
myocardial hypertrophy, usually due to systemic hypertension–> mainly left ventricular hypertrophy
What is the pathogenesis of ischaemic heart disease?
Autoregulation of coronary blood flow breaks down if > 75% occlusion
> 90% stenosis may be insufficient at rest
low diastolic flow especially subendocardial
myocyte dysfunction/death from ischaemia
Active aerobic metabolism of cardiac muscle
What are the different type of angina pectoris?
typical/stable –. fixed obstruction, predictable relationship to exertion
crescendo/unstable –> often due to plaque disruption
variant/Prinzmetal –> coronary artery spasm
What type of angina pectoris is the most dangerous?
Unstable angina as the angina increasingly gets worse
What are the ischaemic heart disease syndromes?
angina pectoris
acute coronary syndrome
sudden cardiac death
chronic ischaemic heart disease
What is acute coronary syndrome?
It refers to a group of conditions due to decreased blood flow in the coronary arteries such that part of the heart muscle is unable to function properly or dies.
Give examples of acute coronary syndrome
acute myocardial infarction (+/- ecg ST elevation)
crescendo/unstable angina
What occurs in subendocardial myocardial infarction?
The subendocardial myocardium is relatively poorly perfused under normal conditions
How can the subendocardial myocardium infarct without any acute cornary occlusion?
If there is:
Stable athermanous occlusion of the coronary circulation
An acute hypotensive episode
Where is it common to get coronary atheroma and thrombus?
Occur in bifurcation, junctions of the coronary arteries or if there is any abnormalitis.
Due to the shear pressures at the time
What is the morphology of heart after MI within the fisrt 24 hours? Explain both gross and microscopic appearance
Gross appearance –> Normal/dark
Microscopic appearance –> necrosis and neutrophils
What is the morphology of heart after MI within post 1-2 days? Explain both gross and microscopic appearance
Gross appearance – more necrosis and neutrophils
What is the morphology of heart after MI within post 3-7 days? Explain both gross and microscopic appearance
Gross appearance –> hyperaemic borderm, yellow centre
Microscopic appearance –> macrophages
What is the morphology of heart after MI within post 1-3 weeks? Explain both gross and microscopic appearance
Gross appearance –> red/grey
Microscopic appearance–> granulation tissue
What is the morphology of heart after MI within post 3-6 weeks? Explain both gross and microscopic appearance
Gross –> scar
Microscopic –> collagen scar
What are the different blood markers of cardiac myocyte damage? When can they be detected?
Troponins T & I
detectable 2 – 3h, peaks at 12h, detectable to 7 days
raised post MI but also in pulmonary embolism, heart failure, & myocarditis.
Creatine kinase MB
detectable 2 – 3h, peaks at 10-24h, detectable to 3 days
Myoglobin
peak at 2h but also released from damaged skeletal muscle
Lactate dehydrogenase isoenzyme 1
peaks at 3days, detectable to 14days
Aspartate transaminase
Also present in liver so less useful as a marker of myocardial damage
Why is creatine kinase not the best marker for MI?
Because creatine kinase is seen in muscles all around the body and not just in the heart.
CK Mb which is mainly found in cardiac is also found in skeletal
What is the prognosis of MI?
20% 1-2h mortality – sudden cardiac death
What are the complications of MI?
Mural thrombus and emboli
arrhythmias, ventricular fibrillation (75-95%) & sudden death
ischaemic pain
left ventricular failure (60%) & shock (10-15%)
Pericarditis
deep leg vein thrombosis & pulmonary embolus (15-40%)
ventricular aneurysm
autoimmune pericarditis (Dressler’s syndrome
Contractile dysfunction and chronic cardiac failure
Infarct expansion
What can be the possible cause of chronic ischaemic heart disease?
coronary artery atheroma produces relative myocardial ischaemia & angina pectoris on exertion
risk of sudden death or MI
possible previous occult MIs
crescendo or unstable angina - evolving plaque
variant angina - coronary arterial spasm