Lecture 11: Physiology And Pharmacology Of Angina Flashcards
What is ischemia?
Insufficiency in blood supply
What is the source of blood supply for the heart muscles?
The coronary arteries
What causes angina?
If the coronary arteries are blocked, the blood supply to the heart will reduce, which will result in chest pain - angina
What is angina pectoris?
The result of ischemia caused by an imbalance between myocardial blood supply and oxygen demand
What gender is angina more common in?
Woman
Angina may occur by..?
- Spasm
- Atherosclerosis
- Atherosclerosis with blood clot
What are the main types of angina?
- Stable
- Unstable
- Printmetals
What is stable angina?
- Most common form
- Caused by a fixed plaque
- Can be prompted by exercise or factors that construct blood vessels or increase blood pressure
- Doesn’t happen at rest
- Responds well to meds
What is unstable angina?
- May occur at rest
- More severe, lasts longer
- Sign that a plaque has ruptured or a thrombus has formed
- Does not respond to rest and meds
What is prinzmetals angina?
Coronary artery spasm: sudden involuntary contraction of smooth muscle tissue or coronary artery
- The spasm temporarily narrows the coronary artery
- Causes transient impairment of coronary blood supply
When does prinzmetals angina usually happen?
At rest
What are the six different classes of stable angina?
- Exertional angina
- Anginal equivalent syndrome
- Syndrome x
- Silent ischaemia
- Decubitis angina
- Nocturnal angina
What is exertional or classical angina?
- Arises from an increase in oxygen demand during exertion or emotion
- Coronary arteries obstructions are not sufficient enough to go result in resting myocardial ischemia
How do you get relief from exertional angina?
Rest and nitroglycerine
What is anginal equivalent syndrome caused by?
Myocardial ischaemia
What are the symptoms of anginal equivalent syndrome?
- Shortness of breath
- Pain at a site other than the chest eg arm or jaw
What is syndrome X?
- Typical, exertional angina with positive exercise stress test.
- Anatomically normally coronary artieries
- Reduced capacity of vasodilation in microvasculature
What is silent ischemia?
Myocardial ischemia without angina
How is silent ischemia diagnosed?
- Holter monitor (records heart rate and rhthym over a 24 hour period)
- Exercise testing
What is decubitis angina?
Chest pain while the patient is lying down
How does decubitis angina occur?
When gravity redistributes fluid in the body - redistribution makes the heart work harder
How is decubitis angina relieved?
By standing or sitting.
What is nocturnal angina?
- Awakes the patient from sleep
- May be provoked by vivid dreams
What can cause nocturnal angina?
Coronary artery spasms
What are the eight causes of angina?
- Significant coronary atheroscelrotic lesion in the large epicardial coronary arteries with atleast a 50% reduction in arterial diameter
- Coronary spasm
- Abnormal constriction or deficient endothelial dependant relaxation of resistant vessels associated with diffuse vascular disease
- Increased extravasular forces, such as severe LV hypertrophy caused by hypertension, aortic stenosis, or hypertrophic cardiomyopathy, or increased LV diastolic pressures
- Reduction in the oxygen carrying capacity of blood, such as elevated carboxyhemoglobin or severe anemia
- Congenital anomilies or the origin and/ or course of the major epicaridal coronary arteries
- Coronary artery fibrosis after chest radiation
- Coronary artery intimal fibrosis following caridac transplantation
What is used for a stable angina assessment?
- History: Grading scale
- Exercise testing
- Electrocardiogram
What is used for the classification of angina severity?
The canadian cardiovascular society grading scale
What is class I angina?
Angina only during strenuous or prolonged physical activity
What is class II angina?
Slight limitation, with angina only during vigorous physical activity
What is class III angina?
Moderate limitation, symptoms with everyday living activities
What is class IV angina?
Severe limitation, inability to perform any activity without angina or angina at rest
What is the goal of exercise testing?
To induce a controlled, temporary ischemic state during clinical and ECG observation
What can be used for exercise testing?
- Treadmill
- Bicycle
- Bruce protocol
How does ischaemia affect an ECG?
ST segment depression occurs with ischaemia and reverses when ischaemia disappears
How does angina affect ECG?
May be normal
What are the steps in atherosclerotic plaque and thrombus formation?
- Initial fatty streak
- Plaque enlarges
- Loss of endothelium and exposure of collagen
- Platelet adherence & activation
- Fibrin meshwork deposition with RBC entrapment
- More flow turbulence, more platelet adherence, more fibrin deposition
- Thrombus of attempting layers, fibrin and red blood cells
What are the preventative factors for angina?
- No smoking
- Diet : reduce fat intake
- Reduce alcohol
- Regular ecercise/ weight control
What is first line therapy of angina?
Beta blockers
What should you add if beta blockers dont control symptoms of angina?
Calcium channel blocker, long acting nitrates or nicorandil
What should you take for immediate relief of angina?
Sublingual GTN tablets or spray
When do you refer a patient with angina to a cardiologist?
If the symptoms are not controlled on maximum theraputic doses of two drugs
How do drugs for angina work?
Lower the oxygen demand of the heart by affecting blood pressure, venous return, heart rate and contractility
Name beta adrenergic receptor blockers
- Atenolol
- Bisoprolol
- Metoprolol
How do beta adrenergic blockers work?
Decrease the oxygen demands of the myocardium by lowering the rate and the force of contraction of the heart
Name calcium channel blockers?
- Diltiazem
- Amlodopine
- Verapamil
What happens when calcium enters a cell?
Contraction
What do calcium channel blockers do?
Prevent entry of calcium into cells via L type calcium channels
Why is calcium influx increaesd in ischemia?
Due to the membrane depolarization that hypoxia produces
Give examples of nitrates (2)
- Glyceryl trinitrate (GTN)
- Isosorbide mononitrate
How do nitrates work?
- Relax coronary arteries by decreasing coronary vasoconstriction or spasm
- Increase perfusion of the myocardium
- Can release calcium in muscle
Name a potassium channel activator
Nicorandil
What does nicorandil do?
it opens potassium channels in the smooth muscle cells of the blood vessels, leading to hyperpolarization, which causes relaxation of the vessels. At the same time, it also releases nitric oxide, a potent vasodilator.
What are the surgical treatments for angina? (3)
- Stenting
- Angioplasty
- Bypass surgery
How is angina diagnosed?
- ECG
- Exercise testing
