Treatment of Angina Flashcards
What shrinks the window that allows for coronary filling?
Shortening diastole by increasing heart rate, increased ventricular EDP via aortic valve stenosis and reduced diastolic arterial pressure via mitral or aortic valve incompetence.
Describe different ways coronary ischaemia and infarction arise
Coronary ischaemia is usually due to atherosclerosis. Sudden ischaemia that may result in cardiac infarction is usually caused by thrombosis. Coronary spasms can cause variant angina.
On a cellular level what results from ischaemia?
Cellular calcium overload due to the decreased oxygen. This may cause cell death and dysrhythmias.
What is Angina Pectoris
Chest pain usually due to inadequate supply of oxygen to the heart which typically produces severe and crushing pain
Describe the characteristic distribution of the pain of angina pectoris
Often retrosternal or left side of chest and can radiate to left arm, neck, jaw and back. It is brought on by exertion, cold or excitement. It is thought that a build up of local factors (adenosine, potassium ect) due to lack of blood washing them away or increased metabolic activity.
What are the three types of angina?
Stable, unstable and Variant (Prinzmetal)
Describe features of stable angina?
Predictable chest pain on exertion and is caused by a fix narrowing around the arteries
Describe features of unstable angina
Occurs at rest with less exertion. It is associated with a thrombus around a ruptured atheroma but without complete occlusion of vessel (similar to MI)
Describe features of Variant angina?
This is uncommon and caused by coronary artery spasm. It is not completely understood but sometimes associated with atherosclerosis
Describe the treatments to reduce chest pain symptoms
Beta-blockers, Nitrates, Calcium channel antagonists, Nicorandil, Ivabradine and Ranolazine
What are the treatments to prolong survival
Bet-blockers, Aspirin, Statins, angiotensin converting enzyme inhibitors and angiotensin 2 receptor blockers
Describe in more detail how you treat symptoms of angina
Can offer short acting nitrate for preventing/treating episodes of angina. Offer a first line treatment (usually beta blockers but can be calcium channel blocker)
Describe what you can do if beta blockers are not optimal?
You can add a calcium channel blocker. If neither are effective then other drugs may be used.
Describe how antianginal drugs work?
Mainly they work by decreasing the metabolic demand of the muscle. Organic nitrates, nicorandil and calcium antagonists are vasodilators which decrease preload and afterload. Beta blockers and Ivabrandine slow down the heart which decreases metabolic demands.
Name two examples of organic nitrates
Glyceryl trinitrate and isosorbide mononitrate.
How do organic nitrates work?
They are powerful vasodilators. They are metabolised to nitric oxide and relax smooth muscle, act on veins to decrease preload and also causes dilation of collateral coronary vessels which improves distribution of coronary blood flow to ischaemic areas.
High doses of organic nitrites can cause what?
It can effect arteries and therefore decreasing afterload, this is more likely to be given in surgical or hospital settings.
What are some of the clinical uses of nitrates in angina?
For stable angina - It can be prevented by sublingual glyceryl trinitrate shortly before exersion or isosorbide mononitrate long before.
Unstable angina - Intravenous glyceryl trinitrate.
Acute heart failure - IV GTN,
Chronic heart failure - Isosorbide mononitrate with hydralazine in African American patients.
What are the unwanted side effects of organic nitrates?
Headaches and postural hypotension
Describe clinical features of beta blockers?
It is the first line treatment in the prophylaxis and treatment of stable and unstable angina. It decreases cardiac oxygen consumption by slowing heart by decreasing sympathetic innervation. Can also have antidysrhythmic action.
Name two examples of beta blockers?
Bisoprolol and atenolol
What are the action of the calcium channel blockers?
They prevent the opening of the voltage gated L-type calcium channels to block calcium entry and prevent muscle cell depolarisation
What are the two main types of calcium channel blockers?
Dihydropyridine derivates (amlodipine) and rate-limiting (verapamil)
What are the effects of calcium channel blockers?
It has vasodilator effects mainly on resistant vessels which reduces afterload and dilates coronary vessels
What is specific about rate limiting CCBs?
Verapamil and diltiazem can reduce and impair AV conduction and myocardial contractility, therefore effects the heart as well as vasculature
What are the clinical uses of CCBs of angina?
Amlodipine or lercanidipine are safe in patients with HF so can be used instead of BBs in variant angina or along side BB in most angina. Veramapil and Diltiazem are contrainticated in HF, bradycardia, AV block or with BB (because both BB and rate limiting CCBs slow HR)
What are the side effects of CCBs?
Headaches, constipation and ankle oedema
Describe the clinical uses of CCBs that are not for angina
Mainly verapamil is used in Antidysrhythmics - It slows ventricular rate in rapid AF and prevents recurrence of supraventricular tachycardia, however no effect on ventricular arrhythmias.
Hypertension - Mainly amlodipine or lercanidpine
Name and describe potassium channel activators
Nicorandil. It combines activation of potassium channels with nitrovasodilator actions causing hyperpolarisation of smooth muscle (meaning stronger signal is needed to depolarise muscle) However causes headaches, flushing and dizziness. Used in patients who remain symptomatic despite other treatment
Describe the effects of Ivabradine
Inhibits F-type sodium channels in the heart, reducing cardiac pacemaker activity and inhibiting heart rate.
Describe the effects of Ranolazine?
Unique anti-anginal medication which is used as a last resort
