Cardiology Flashcards
Abciximab - MOA, use and risk
Monoclonal antibody that irreversibly binds to the GPIIb/IIIa glycoprotein receptors
This prevents final common pathway of platelet activation/ aggregations
Used to prevent thrombosis/ restenosis in patient’s undergoing stenting for unstable angina. Also Glycoprotein (GP) IIb/IIIa inhibitors are often used as a rescue or bailout therapy to manage complications arising during percutaneous coronary intervention, rather than as prophylactic treatment. Usually used where there is a high thrombus burden.
Main risk is thrombocytpaenic haemorrhage. For this reason you only use is once. Can be reversed by platelet administration.
Examples of simililar drugs include tirofiban and eptifibatide
Adenosine
MOA, use, side effects, which patient’s should not be given adenosine?
Purine nucleoside with short half life of 8-10 seconds
Acts via adenosine receptors, activating K+ channels in SAN and AVN.
Used to terminate SVT and is used to diagnostically distinguish SVT from VT. Duration of action is significantly increased by conocurrent use of dipyridamole.
Makes you feel as if you are going to die - anxiety, bronchospasm, flushing, chest tightening.
AVOID IN ASTHMA.
Amiodarone
Drug class
MOA
Side effects
Monitoring
Class III antiarrhythmic that works via blockade of the rectifier voltage gated K+ channels during repolarisation phase (III) of cardiac action potential. Also has sodium blockade action and beta blocking activity (dirty drug).
Use: Treatment of tachyarrhythmias, like VF, AF, flutter and WPW. Used generally second line.
Risks:
Long QT syndrome as you are stretching out the cardiac action potential –> TDP
Increased effects of Warfarin and Digoxin
Thyroid (hyper or hypo)
Slate grey rash
Lung fibrosis
Liver dysfunction
Thrombophlebitis
Corneal deposits
Photosensitivity
Parasthesias
Monioring: LFTs, CXR and TFTs before treatment. U&Es need to be monitored regularly to look at potassium levels.
What are the different classes of antiarrhythmics?
I: Sodium channel blockers
II: Beta blockers
III: Potassium channel blockers
IV: CCBs and miscellaneous
Calcium channel blockers
Promotes vasodilation, reduces myocyte contractility and delays cardiac action potential.
Indications: HTN, Angina, class 4 antiarrythmics (AF, atrial flutter) and Raynaud’s phenomenon. .
Risks: Swollen legs, reflex tachycardia, flushing, bradycardia, constipation, hyperprolactinaemia, gum hypertrophy
Contraindications: Heart failure and bradycardia
Examples of common calcium channel blockers
Dihydropiridines all end in dipine and are specific to the peripheral vessel smooth muscle. E.g. Amlodipine, Felodipine, Nicardipine, Nifedipine. Uses: HTN, cardiac vasospasm, Raynaud’s Phenomenon and subarachnoid haemorrhages.
Non-dihydropirines are more specific to the heart. E.g. Diltiazem or Verapamil so are used as class IV antiarrhythmics in treatment of atrial fibrillation and flutter. Also used for angina.
Nicorandil
Vasodilatory drug - works via nitrate action AND as a potassium channel openeer.
Contraindicated - hyperkalaemia, hypotensive shock, LV failure, pulmonary oedema
Very common to get headache (50% people), flushing and dizziness
Aliskiren
Direct renin inhibitor (inhibits conversion of angiotensinogen to angiotensin 1). Treatment of essential HTN either alone or in combination with ARBs/ACEi
Main risks: Renal impairment, hyperkalaemia. Beware of using it with other drugs that cause hyperkalaemia.
ACE inhibitors
Reduces mortality in:
- Heart failure
- MI
- Diabetic nephropathy
Contraindications:
- Bilateral funtional renal artery stenosis
- Severe renal impairment
Main SE are dry cough, hyperkalaemia and hypotension
ARBs
Examples: Losartan, Candesartan, Irbesartan, Valsartan
Improved survival in:
- HTN
- Cardiac failure
- MI
- Diabetic nephropathy
Risks: cough (less common than ACEi) and cannot be used in bilateral renal artery stenosis (same as ACEi)
Examples of thrombolysis agents and main contraindications
Streptokinase, Alteplase, Reteplase, Tenecteplase
Absolute: Active bleeding, intracranial neoplasm, history of brain haemorrhage/stroke, pregnancy, aortic dissection, head trauma, BP > 200/120
Relative: Anticoagulation, bleeding disorders, prolonged CPR, recent surgery, predictable intracardiac thrombus (AF + mitral stenosis), active diabetic retinopathy, INR>1.8
Ticagrelor
Platelet aggregation inhibitor that works via P2Y12 inhibition. Used to reduce long term stroke risk after MI.
Uses:
- Medical management of STEMI/ NSTEMI where PCI is inappropriate
- Typically given for 1 year
- Dont give in combination with an anticoagulant
Risks: Dyspnoea and bradycardia (adenosine like action). Don’t give to patients with a high bleeding risk.
Bivalirudin
Direct thrombin inhibitor, given IV during pPCI alongside a bailout GPi (e.g. Abciximab)
Main benefit is reduced bleeding compared to other drugs (hence NICE guidelines recommended if femoral access being used) but main risk is increased stent thrombosis.
Clopidogrel
300-600mg given as loading dose for primary PCI
75mg given as part of DAPT for 1 year post MI (if you are not using Ticagrelor). 600mg has been found to achieve platelet aggregation more quickly and is appropriate for STEMI.
MOA: The active metabolite of clopidogrel selectively inhibits the binding of adenosine diphosphate (ADP) to its platelet P2Y12 receptor and the subsequent ADP- mediated activation of the glycoprotein GPIIb/IIIa complex, thereby inhibiting platelet aggregation. This action is irreversible.
Prasugrel
MOA: Prasugrel is a thienopyridine, an irreversible antagonist of the ADP P2Y12 receptor.
More potent than Clopidogrel, given only for those undergoing PCI according to NICE guidelines. Don’t give if >75, weighing <60kg, previous stroke/TIA.
Fondaparinux
Use
MOA, who should NOT be given it?
Fondaparinux selectively binds to antithrombin III.
Don’t give if:
- About to undergo PCI
- Low weight
- Poor renal function
- High bleeding risk
Fondaparinux is given for NSTEMI for 1 week prior to non-urgent PCI.
Indapamide mechanism of action
Indapamide is a thiazide-like diuretic drug used in the treatment of hypertension, as well as decompensated heart failure.
NOTE: preferred to bendroflumethiazide in treatment of HTN
Digoxin
MOA: Digoxin is a cardiac glycoside that increases the force of myocardial contraction and reduces conductivity within the atrioventricular (AV) node.
Note: You an get a ‘reversed tick’ ST depression in inferolateral leads with digoxin therapy, but can also indicate toxicity
Uses: AF, Atrial flutter, heart failure
Digoxin toxicity
- Don’t diagnose on Digoxin level alone as this can be normal
- Can get almost any arrhythmia including heart block and atrial arrhythmias
- Typically: severe bradycardia, hypotension, hyperkalaemia, anorexia, nausea/vomiting, yellow vision (xanthopsia), diarrhoea, gynaecomastia
Predisposing factors to Digoxin toxicity:
- Hypokalaemia and any drugs causing hypokalaemia (e.g. thiazides)
- Hypomagnesia
- Hypercalaemia
- Amiodarone
- Quinine
- Calcium antagonists
- Renal failure
- Hypothyroidism
Management
- Digibind
- Correct hypokalaemia
- Correct arrhythmias
Flecainide
MOA: Class 1c antiarrhythmic - works via sodium channel blockade to inhibit the upstroke of the cardiac action potential. Reduces heart rate and contractility.
Uses: cardioversion in SVT/AF, ventricular arrythmias, pre-exitation syndromes
Risks: DONT USE after an MI or in heart failure - can be pro arrhythmic in these patients.
Side effects: vertigo, visual disturbance
What causes a prolonged PR?
Delayed conduction through the AV node
Normal variant
Athleticism
Hyperkalaemia
Drugs: BB, CCB, Digoxin, Amiodarone
Inferior MI
Mitral valve surgery
Statins
MOA
Risks
Target cholesterol levels
MOA - HMG co-reductase inhibitors, which is the enzyme normally most active during sleep. Also will upregulate LDL receptors and decrease HDL receptors
Main risk is rhabdomyolysis in 10-20% of patients. Worse if renally impaired or combined with a fibrate.
DON’T combine with clarithromycin.
Aim total cholesterol <4mmol/L and LDL <2mmol/L
Ivabradine
Acts as a funny current inhibitor (an inward sodium channel) found predominantly in the SAN. It results in a reduced resting heart rate.
Uses: Angina and heart failure. Can avoid the symptoms attributed to reduced peripheral blood flow with beta blockers.
Note that the algorithm for angina states to try a BB or CCB as first line. If this doesn’t work, try either Ivabradine, Nicorandil, Ranolazine or ISMN monotherapy second line).
Risks: Don’t use with concurrent BB or CCB. Avoid in sick sinus syndrome.
Thiazide and Thiazide-like diuretics
Examples
MOA
Uses
Risks/ SE
Thiazides = Bendroflumethiazide or Metolazone
Thiazide-like = Indapamide or Chlortalidone
They work by inhibiting sodium resorption at the DISTAL CONVOLUTED TUBULES - via the NaCl symporter. Potassium will be lost as a result.
Uses: Thiazides really only used for mild heart failure now, although loops are still first line. Indapamide and other thiazide-like diuretics are third-line for HTN.
Adverse effects: hyponatraemia, hyPERcalcaemia, hypokalaemia, hypotensive/dehydration symptoms, gout, impotance
Rare: Agranulocytosis, thrombocytopenia, photosensitivity, pancreatitis.
Noval oral anticoagulants
Apixaban and Rivaroxaban
Factor Xa inhibitors
Now first line for AF/ VTE
Dabigatran
Direct thrombin inhibitor. Main thing to remember is it shouldnt be used if Creatinine Clearance <30 and it can be reversed via administration of Idaricizumab.
Liscenced for following uses:
- VTE prevention post knee/hip surgery
- Non-valvular AF as long as following criteria met: previous thromboembolic disease, LVEF<40, NYHA 2 or above, age >75 or age>65 but coexistant diabetes, CAD or HTN.
IMPORTANT CONTRAINDICATIONS: Don’t give DOACs to those with antiphospholipid syndrome (can increase thromboembolic events) and efficacy with prosthetic heart valves has not been established so persist with Warfarin.
