Angina Pectoris/Myocardial Infraction Flashcards
How is angina presented in a patient? And what causes this to occur?
Patients experiencing angina will experience it in the form of chest pain and shortness of breathe, this chest pain occurs due to a poor oxygen supply to cardiac muscle causing the heart to switch to anaerobic metabolism.
There are 5 types of angina, what are they?
C U P D N
First is classical angina.
Second is unstable angina.
Third is prinzmetals variant angina.
Fourth is Decubitus angina.
Finally is Nocturnal angina.
When treating angina, what is the aim of drug treatment?
The aim of drug treatment in angina is to reduce cardiac workload which reduces the hearts oxygen demands or increase oxygen supply by improving its flow.
Nitrates are used in the treatment of angina to reduce the workload of the heart. What mechanism are used to produce this effect?
The effects produced by nitrates are vasodilator effect these occur in 3 main areas…
Venous capacitance vessels this reduces venous return by pooling blood this decreasing stretch on ventricular wall.
Arterial resistance vessels reduced resistance encountered when in systole lowering BP.
Coronary arteries.
All these effects cause a reduction in oxygen demand by reducing cardiac workload.
Nitrates are converted into nitric oxide. Why is this key in the mechanisms of nitrates?
Nitric acid stimulates the production of cGMP which cause a increased uptake of calcium ions thus reducing the interaction of calcium ions and calmodulin so the muscle relaxes and vessels dilate.
What other drug treatment options are available to patients suffering from angina?
How do they aid the treatment of angina?
Beta-adrenoceptors antagonists and calcium channels blockers.
Beta1-adrenoceptors antagonists reducing cAMP decreasing the heart rate and the strength of contraction thus reducing the hearts oxygen demand.
Calcium channel blockers reduce calcium ions this causes vasodilation reducing the pressure experienced by the heart when ejecting blood thus reducing oxygen demand.
Ivabradine is a sinus node inhibitor offered to patients as an alternative to beta blockers.
How does this medication work and what occurs as a result?
Ivabradine inhibits the If current in the sinoatrial node which slows depolarisation caused by potassium and sodium ions diffusing in. This reduces heart rate reducing oxygen demand.
Ranolazine produces a negative inotropic effect. What is meant by this term and how is this effect achieved ?
Inotropic is used to define the strength of contraction and a negative impact means less strength is required to contract. Ranolazine achieves this by inhibiting late sodium ion currents reducing calcium ion concentration reducing cardiac oxygen demand.
Nicorandil is given as to produce a vasodilation and muscle relaxation. How is this effect achieved?
Nicorandil acts as a nitrovasodilator, this stimulates guanylate cyclase to activate calcium ion pumps reducing intracellular concentration resulting in the dilation.
Why and when does classical stable angina occur?
This angina occurs during exertion when the heart is unable to meet increased cardiac demands and can be relieved with rest.
Why and when does unstable angina occur?
This occurs rapidly at rest and is caused by the rupture of plaques forming thrombi which partially obstruct coronary arteries causing ischaemic pain and cause sudden reduced blood supply.
What can unstable angina lead to?
Unstable angina can lead to a heart attack.
What is the the name given to ischaemia that occurs without symptoms?
Silent ischaemia.
What is given to patients to relieve symptoms of unstable angina?
Glyceryl trinitrate is used to relieve symptoms.
What events occur in the arteries to give rise to a myocardial Infraction?
Myocardial Infraction arise from complete coronary artery occlusion following rupturing of atherosclerotic plaques.
