CVS Flashcards
Digoxin: Mechanism of Action
It is negatively chronotropic as it slows conduction at the AV node by increasing vagal tone.
It is positively intotropic as it inhibits Na+/K+ pumps. This causes an increase in intracellular sodium, and therefore reduces Ca2+ excretion so Ca2+ accumulates in the myocytes and their contractility is increased.
Digoxin: Indications
AF and atrial flutter, though a B blocker or CCB is usually more effective
In severe heart failure, as 3rd line treatment after B blocker and ACEI and spironolactone/ARB
Digoxin: Adverse Effects
Bradycardia, GI upset, rash, dizziness, visual disturbance.
It is pro-arrhythmic
Digoxin: Warnings and Interactions
Low therapeutic index. OD can cause weird and wonderful arythmias.
It is contraindicated in those at risk of ventricular arrhythmia or heart block
It is really excreted so dose should be reduced in renal impairment
Hypokalaemia and hypercalcaemia increase the risk of digoxin toxicity
Interacts with loop/thiazide diuretics as they can cause hypokalaemia
Digoxin: Prescription
Oral or IV
Large volume of distribution so loading dose is required
Cardiac monitoring!
Diuretics, Loop (Furosemide): Mechanism of Action
Inhibit Na/K/2Cl transporter in ascending limb. Also causes dilation of capacitance veins.
Diuretics, Loop (Furosemide): Indication
Acute pulmonary oedema
Chronic heart failure
Other oedematous states
Diuretics, Loop (Furosemide): Adverse effects
Dehydration, hypovolemia, loss of electrolytes
Hearing loss at high doses
Diuretics, Loop (Furosemide): Warnings and Interactions
Contraindicated in dehydration or hypotension, and hypokalaemia
Can worsen gout as they inhibit uric acid excretion
Increase levels of renal excreted drugs
Increase ototoxicity of ahminoglycosides
Cause digoxin toxicity by hypokalaemia
Diuretics, Loop (Furosemide): Prescription
Oral and IV
Periodic monitoring of electrolytes for safety
CCBs (Amlodipine): Indications
Hypertension
Non-dihydropyridine drugs (verapamil) are anti-arrhythmic and can be used to treat SVT, AF and flutter
CCBs (Amlodipine): Mechanism of Action
Decrease Ca2+ entry, so decrease smooth muscle contractility. They also slow conduction, especially across the AV node.
CCBs (Amlodipine): Adverse Effects
Ankle swelling, flushing, headache and palpitations
Verapamil can cause bradycardia
CCBs (Amlodipine): Warnings and Interactions
Verapamil SHOULD NOT be prescribed alongside a B blocker as this can cause dangerous bradycardia or even ayststole
Should be avoided in unstable angina as they can increase myocardial oxygen demand
CCBs (Amlodipine): Prescription
Taken orally (except verapamil can be given IV for acute arrhythmia) Amlodipine has a long half life so can be given once daily Monitering is based on symptoms and BP measurements
Lidocaine: Indications
Local anaesthetic
Uncommonly as anti arrhythmic for VT and VF that cannot be cardioverted
Lidocaine: Mechanism of Action
Na+ channel blocker, so prevents initiation and propagation of action potentials
In the heart it reduces the duration of the action potential, slows conduction and increases the refractory period
Lidocaine: Adverse Effects
Drowsiness, tremor, fits
Effects more pronounced when used systemically
OD can cause hypotension and arrhythmia
Lidocaine: Warnings and Interactions
Dose reduction in patients with reduced CO
Beneficial interaction with adrenaline (local vasoconstrictor)
Lidocaine: Prescription
Maximum dose is based on body weight
Foundation doctors should not prescribe it systemically
Amiodarone: Indictions
A wide range of tachyarrhythmias e.g. AF, SVT, VT, VF…
Generally when other treatments have been ineffective
Amiodarone: Mechanism of Action
It is a Class III drug so blocks K+ channels (It actually also blocks Ca2+, Na+ and antagonises adrenoreceptors)
This reduces spontaneous depolarisation, decreases conduction velocity and increases resistance to depolarisation
Amiodarone: Adverse Effects
Hypotension
When taken chronically: pneumonitis, hepatitis, bradycardia
Amiodarone: Warnings and Interactions
Actually quite a dangerous drug, so consider risks and benefits
Avoid in thyroid disease, hypotension or heart block
It interacts with lots and lots of drugs; especially digoxin and verapamil
Amiodarone: Prescription
Requires senior input
Continous cardiac monitoring
Beta Adrenoceptor Blockers: Indications
Ischaemic Heart Disease Chronic Heart Failure Atrial Fibrillation SVT HTN, when ACEIs and CCBs have not worked
Beta Adrenoceptor Blockers: Mechanism of Action
Then antagonise B1 receptors. They are negatively chronotropic and inotropic
They also increase the refractory period at the AV node
They reduce renin secretion
Beta Adrenoceptor Blockers: Adverse Effects
Hypotension, cold peripheries, GI upset, fatigue, headache
Beta Adrenoceptor Blockers: Warnings and Interactions
Should be avoided in asthmatics (bronchospasm)
In heart failure, start at a low dose and slowly increase as they can initially impair cardiac function
AVOID with VERAPAMIL as this is bad (bradycardia, asystole)
Beta Adrenoceptor Blockers: Prescription
Monitoring is based on symptoms and heart rate
Timing doesn’t matter
ACEI: indications
First line treatment of HTN
Heart failure
Ischaemic Heart Disease
ACEI: Mechanism of Action
Inhibit ACE. Reduces AT2 levels, so reduces after load. Reduces aldosterone levels so less sodium retention
ACEI: Adverse Effects
Coughing, hypotension,
Rare: idiosyncratic angiooedema
ACEI: Warnings and Interactions
Can cause hyperkalaemia and worsen renal failure, so should be avoided in AKI
Should be avoided in combination with other potassium elevating drugs
Combination with NSAID increases the risk of renal failure
ACEI: Prescription
Taken orally
Can be useful to take before bed to reduce hypotension
Tell patient to avoid NSAIDs
Monitoring is based on symptoms, BP and checking electrolytes for safety before treatment and after 1-2 weeks
ARB: Indications
HTN , esp. when ACEI is not tolerated
ARB: Mechanism of Action
Block AT1 receptor
Reduces vasoconstriction and aldosterone levels
ARB: Adverse Effects
Hypotension, hyperkalaemia and renal failure
ARB: Warnings and Interactions
Avoid in renal disease e.g. AKI
Avoid in combination with other potassium elevating drugs
Combination with NSAIDs increases risk of renal failure
ARB: Prescription
Taken orally, dose before bed to reduce effects of hypotension
Advise to avoid NSAIDs
Monitoring is based on symptoms, BP and checking electrolytes for safety before treatment and after 1-2 weeks
Statins: Indications
Primary and prevention of cardiovascular disease
Primary hyperlipidaemia
Statins: Mechanism of Action
Inhibit HMG-CoA Reductase so decrease cholesterol production by the liver and reduce LDL/Cholesterol levels
Statins: Adverse Effects
Generally well tolerated: headache, nausea, muscle aches
Rarely cause more serious muscle issues : rhabdomyolysis, myopathy
Rare but serious: hepatitis
Statins: Warning and Interactions
Caution in hepatic impairment
Dose reduction in renal impairment
CYP450 interactions!
Statins: Prescription
Taken orally once daily
Lipid level before starting treatment
ALT/AST for safety
