Coronary Heart Disease, Angina, MI and Embolism Flashcards
What conditions count as coronary artery disease?
Sudden cardiac death Acute myocardial infarction Unstable angina Stable angina pectoris Heart failure Arrhythmia
What two categories to patients presenting with sudden onset chest pain fall into?
Acute myocardial infarction
Progressive (unstable) angina
How has the mortality from cardiovascular disease changed over the past 50 years?
It has decreased by 50%
Incidence of stable angina has increased
Describe the division of the coronary resistance between the epicardial and intramyocardial vessels.
Normally, the resistance is divided 50:50 in the epicardial vessels and in the intramyocardial vessels
Arterioles dilate in response to what?
Blood pressure - this is autoregulation
What happens to the coronary vessels if there is epicardial stenosis?
The intramyocardial arteries can dilate to some extent to compensate for the increase in the epicardial vessels due to stenosis. The dilation of the intramyocardial arteries can maintain adequate blood flow to the tissues.
At what point does coronary blood flow begin to change?
When stenosis exceeds 70%
What is coronary flow reserve? What does it indicate?
Ratio of resting coronary blood flow to blood flow achieved under maximal stress.
Coronary flow reserve indicates the ability of the coronary circulation to adapt to increasing demand in the face of increasing epicardial stenosis.
Describe angina pectoris?
Tight feeling in the chest that radiates to the jaw, shoulder, back or arms.
What are anatomical tests in coronary artery disease used for?
Coronary artery angiograms - can be used to determine where the narrowing is
What can be done to reduce myocardial oxygen demand following myocardial infarction?
Beta blockers to reduce the heart rate
Describe what the differences are between a white thrombus and a red thrombus.
White thrombus is platelet rich and usually found in arterial thrombosis
Red thrombus is fibrin rich with trapped erythrocytes and is found in low pressure or venous situations
Describe the changes in shear stress at a point of arterial stenosis.
The narrowing itself will have a very high shear stress.
The area distal of the narrowing will have low shear stress and so will promote endothelial dysfunction and accelerate atherogenesis.
What can be made from the cellular constituents of atherosclerotic plaque that could trigger coagulation?
Tissue factor
What is the main biochemical test for myocardial infarction?
Troponin
What criteria define acute myocardial infarction?
A rise or fall in cardiac troponin exceeding the 99th percentile AND at least one of the following:
Symptoms suggestive of ischaemia
Pathological Q wave
New or presumed new ST-T changes or LBBB on ECG
Imaging evidence of new loss of viable myocardium
Identification of intracoronary thrombus or angiography or autopsy
Which isoforms of cardiac troponin are specific to cardiac muscle and how long is it detectable for?
I and T
2 weeks
What are the two types of acute coronary syndrome and what do the ECG changes show?
ST elevation - shows a complete occlusion in the coronary artery
NO ST elevation - could present as ST depression, inversion of the T wave or a normal ECG - shows partial occlusion that embolises distally into the microcirculation resulting in myocardial cell death and troponin elevation.
What is PPCI?
Primary Percutaneous Coronary Intervention (or coronary angioplasty)
A catheter is passed into the coronary artery where the stenosis is and a balloon and stent is deployed to recanalise the vessel.
Where does the myocardial necrosis zone start and how does it spread?
The myocardial necrosis zone starts in the inner part of the myocardium and then spreads outwards until it is transmural. The subendocardium is the work horse of the muscle and gets hit worst and first.
What are the problems with reperfusing damage to the heart muscle?
The act of reperfusion itself may cause damage to the heart muscle.
Describe adverse left ventricular remodelling and its consequences.
Adverse left ventricular remodelling involves thinning of the scar tissue, expansion of the heart muscle and impairment of heart function. This leads to increased risk of heart failure and arrhythmia. Dilation of the heart muscle (according to the Law of Laplace) means that there is increased wall tension. It causes reduced myocyte shortening, ventricular arrhythmias and ventricular fibrillation.
Name two drugs that cause plaque stabilisation.
ACE inhibitors and statins
Name four types of embolism other than a thromboembolism.
Air, Fat, Tumour, Amniotic Fluid
