Pathophysiology of MI
What are the kinds of MI
Where does the electrical impulses in the heart begin
SAN
What is the MOA of class II antiarrhythmics (50 Pts)
Give 1 example (50)
Beta blockers
Beta-adrenergic receptor antagonists Inhibits sympathetic stimulation - Block the effects of adrenaline Reduce heart rate, cardiac output, and blood pressure
Propranolol
Atenolol
Bisoprolol
Metoprolol
n What is an ectopic pacemaker
An ectopic pacemaker is an excitable group of cells that causes a premature heart beat outside the normally functioning SA node of the heart.
What is the management of an MI
MONA:
Name 5 symptoms of an MI
chest pain.
dyspnoea
sweating
nausea
vomiting
Why are signals in the AVN delayed
Because the AV node has a longer refractory period than the rest of the conduction system, it takes longer for the electrical impulse to travel from the AV node to the AV bundle due to the smaller number of gap junctions between the cells.
This delay allows time for the atria to fully contract and push blood into the ventricles before they contract.
What is the MOA of class V antiarrhythmics (150 Pts)
Give 1 example (50)
Atypical eg Digoxin
Cardiac slowing and reduced rate of conduction through AV node
Increased force of contractions
Disturbance of rhythm and increased ectopic pacemaker activity
What would you notice on ECG with ventricular arrhythmias
They are almost always wide QRS complex arrhythmias.
How does a PCI work
In this procedure the blocked arteries are opened up using a balloon (angioplasty) following which a stent may be deployed to prevent the artery occluding again in the future. This is done via a catheter inserted into either the radial or femoral artery
How would you investigate for an MI
Action potential is conducted to the myocardiocytes through what kind of cell junction
Intercalated discs
What is the MOA of class IV antiarrhythmics (250 Pts)
Give 1 example (50)
L-TYPE CALCIUM CHANNEL BLOCKER
MoA: Slows the movement of calcium into the heart and blood vessel walls
Reduces heart rate, force of contraction, and blood pressure
Examples: Nifedipine, Diltiazem, Amlodipine, Verapamil
What is ventricular fibrillation and how can it lead to death
Ventricular fibrillation is the chaotic depolarisation of the ventricles. This results in an arrested cardiac pump function and immediate death
n Where & when is ventricular tachycardia more likely to happen
Often origin around old scar tissue in the heart e.g. after an MI
Difference between a STEMI & NSTEMI
Pathology (200 pts)
ECG (200 pts)
STEMI results from complete and prolonged occlusion of an epicardial coronary blood vessel and is defined based on ECG criteria while NSTEMI is a type of heart attack that usually happens with coronary artery narrowing, transient occlusion, or microembolization of thrombus and/or atheromatous material - i.e., partial or temporary occlusion.
STEMI-ST elevation and NSTEMI - normal ECG or minor T wave changes (inversions) & minor ST depression
Why does repolarisation take a while in cardiac muscle
Repolarisation takes a while in cardiac muscle to prevent the muscles from going into tetanus (prolonged contraction).
What is the MOA of class III antiarrhythmics (350 Pts)
Give 1 example (50)
Potassium channel blocker
Extends the refractory period and delays repolarisation Blocks transmission of abnormal signals and terminates arrhythmia
Amiodarone
Sotalol
Ibutilide
Bretylium
What is ventricular tachycardia and how can it lead to death
- A sequence of three or more ventricular beats
Cardiac output is strongly reduced during VT resulting in hypotension and loss of consciousness. Can deteriorate into ventricular fibrillation.
List the 5 secondary prevention drugs for an MI (80 pts each)
Describe the pathophysiology causing an MI
Name the sequence that electrical signals travel in the heart
SAN
AVN
bundle of His
left and right and bundle
Purkinje fibres which are spread throughout the ventricles
The impulses cause the ventricles to contract from base up
What is the MOA of class Ia antiarrhythmics (150 Pts)
What is the MOA of class Ib antiarrhythmics (150 pts)
What is the MOA of class Ic antiarrhythmics (150 pts)
Give 1 example of each (50 pts)
Class I - Agents that interfere with the sodium channel Ia - Lengthens the action potential eg Quinidine, Procainamide, Disopyramide
Ib - Shortens the action potential eg lidocaine, phenytoin
Ic - No significant effect on action potential eg Flecainide, Encainide, Propafenone
What is ventricular flutter and how can it lead to death
Ventricular flutter is mostly caused by re-entry with a frequency of 300 bpm. The ventricles depolarise in a circular pattern, which prevents good function. Most often this results in a minimal cardiac output and subsequent ischemia. Often deteriorates into ventricular fibrillation.
What are the 2 systems for breaking bad news (250 pts each)
SPIKES
Setting up Perception Invitation Knowledge Emotions Strategy and summary
ABCDE
Advanced preparation Building a relationship Communicate well Deal with patient reactions Encourage and validate emotions