dysrhythmias Flashcards
what is useful for SVT
IV adenosine
adenosine target
G protein-coupled adenosine A1 receptor
adenosine moa
Inhibits adenylyl cyclase enzymes = less cAMP, This promotes opening of adenosine-sensitive potassium channels and increased K+ efflux – as a result cells in the atrioventricular node of the heart become hyperpolarised. This slows the rate of rise of the pacemaker potential
adenosine overall aim
slow AVN conduction
adenosine adverse effects
chest pain, dyspnoea, bronchospasm and nausea
how to resolve adenosine adverse effects
will resolve when the drug is metabolised
amiodarone target
Na channel, Ca channel and α-adrenoceptors
amiodarone overall effect
prolongs the cardiac action potential seen as an increase in the QT interval on the ECG
common adverse effect of amiodarone
Corneal microdeposits
bad adverse effects of amiodarone
Thyoid disorders – hypothyroidism, hyperthyroidism Pulmonary fibrosis Phototoxicity Peripheral neuropathy Optic neuritis/neuropathy (blindness) Hepatotoxicity Slate-grey skin discolouration
what should patients avoid after starting amiodarone
exposure to direct sunlight
digoxin drug class
cardiac glycoside
digoxin target
Na+ K+ ATPase membrane pump
digoxin moa
Increase intracellular sodium = rise in intracellular calcium through the Na+ Ca2+ exchanger on cardiac myocytes. Phases 4 and 0 of the cardiac action potential are prolonged leading to an increase in end diastolic volume.
digoxin affect on the heart
Positive inotropic effect
negative chronotropic
digoxin treats
AF and AF
digoxin therapeutic window
narrow
digoxin toxicity symptoms
Confusion; Loss of appetite; Nausea, vomiting, diarrhoea; Evidence of cardiotoxicity – palpitations, arrhythmias, conduction disturbances; Blurred or yellow vision
lidocaine is used for
anaesthetic
lidocaine blocks
sodium channels
lidocaine works on what phase of the cardiac cycle
0
lidocaine can treat
VT
Flecainide acts on
sodium channels in the purkinje fibers
Flecainide blocks
sodium channels
sotalol moa
adrenergic beta-antagonist
anticholinergic
atropine
atropine inhibits
muscarinic acetylcholine receptor
atropine treats
bradychardia