Cardiac Flashcards
What are the possible interactions of nitrates?
- Not to be used in combination with phosphodisterase inhibitors e.g. viagra (prolongs and enhances hypotensive effect)
- Anti-hypertensive medication (precipitate hypotension)
What are the side effects of amiodarone?
- ACUTE: Hypotension
Chronic Use
- Bradycardia, AV block
- Pneumonitis
- Hepatitis
- Photosensitivity, grey discolouration of skin
- Due to high iodine content, can cause thyroid abnormalities (hyper/hypothyroidism)
What is the mechanism by which furosemide acts?
- Inhibits Na/K/Cl cotransporter in ascending loop of henle → increases electrolytes in lumen → increased diuresis
- Increased dilation of capacitance veins → reduces preload and increases contractile of overstretched muscle
What are the side effects of thiazide diuretics?
- Hypo - Na/K+ (particularly K+ due to increased Na going to distal tubule → increased exchange with K+ → increased K excretion
- Arrythmias (due to hypo-K+)
- Hyperglycaemia, hyperlipidaemia and hypercholesteraemia (increased LDL)
- Impotence in men
What are the SE of beta blockers?
- Bronchospasm
- Bradycardia, reduce cardiac contractibility
- Fatigue
- Peripheral vascoconstriction - cold extremities and Raynaud’s
- Headache
- GI disturbance
- Sleep disturbance/nightmares/hallucinations
- Male impotence
What are the side effects of ACEi?
Hypotension (part 1st dose)
Persistent dry cough - ACE breaks down bradykinin. Blocking it increases bradykinin.
Hyperkalaemia - lowered aldosterone promotes K+ sparing
Renal failure - particularly in combo with NSAIDs - glomerular arteriole needs to be constricted to maintain filtration
Angiooedma/anaphylactic reactions (rare)
What are the CIs for using clopidogrel?
- Active significant bleeding
- Elective surgery (stop 7 days prior)
Caution:
- Kidney and hepatic disease (particularly with active bleeding)
What is the mechanism by which ACEi work?
- Blocks ACE which converts angiotensin I to II (lungs)
- Angiotensin II is a vasoconstrictor and stimulates aldosterone secretion - reduces pheriperhal vascular resistance/afterload
- Dilates the efferent glomerular arteriole - reduces intraglomerular pressure and slow progression of CKD
- Reduced aldosterone - promotes water/Na+ excretion - help reduce venous return (reduced preload) - beneficial to HF
What are the indications for beta blockers?
- IHD - 1st line - angina and ACS - improves symptoms and prognosis
- HF - 1st line - improves prognosis by reducing chronic synmpathic stimulation
- AF - 1st line - reduces VT and paroxysmal AF - prolonging AV node refrac period and restores sinus R
- SVT - 1st line - restores sinus R
- HTN - not indicated for intial therapy but for when other medicines e.g. ACEi, diuretics etc fail to work
What time of day should diuretics be taken?
In the morning/afternoon - to avoid nocturia
Name some of the possible interactions of digoxin?
Thiazide/loop duiretics (reduced K+ - increased risk of toxicity)
AMIODARONE, calcium channel blockers, spirolactone, quinine - increases plasma conc and risk of toxicity
What are the potential SEs for AT1 blockers?
- Hypotension (part after 1st dose)
- Hyperkalaemia (aldosterone promotes K+ excretion)
- Renal failure (esp with renal stenosis)
DOES NOT CAUSE PERSISTENT COUGH
How are AT1 blockers excreted?
Renally and hepatically
What are the SEs of Aspirin?
- GI irritation/ulceration/haemorrhage
- hypersensitivity
- Tinnitus (high, frequent doses)
- Overdose: hypervent, hearing changes, confusion, convulsions, resp arrest
Name some sytochrome P450 inducers?
Phenytoin, carbamezapine, rifampicin
What is the mechanisms by which thiazide diuretics work?
- Act on Na/Cl cotransporter in distal convoluted tubule (block)
- Prevents Na reabsorption and osmotically associated water - increased diuresis
- Usually reversed by compensatory changes e.g. RAS system
- However, also has vasodilatory effect by some unknown mechanism which reduces BP
WHat drug class does furosemide belong to?
Loop diuretics
How is aspirin eliminated?
Renally
What are the contraindications of ACEi?
Acute kidney injury/renal stenosis
Hepatic failure
Caution: Pregnant or breastfeeding; CKD
What are the CIs for aspirin?
- <16 yrs - Reyes syndrome (rare, lifethreatening syndrome affecting liver and brain)
- Aspirin allergy - hypersensitivity
- Pregnancy - 3rd trimester - prostaglandin inhibition → premature occlusion of ductus arteriosus
- Peptic ulcer
- Gout - may precipitate attack
What are the SEs of potassium diuretics?
- GI upset
- Hyperkalaemia or hyponatramia
- Hypotension/dizziness (particularly in combo with loop/thiazide)
- Urinary symptoms
What type of drug is warfarin?
Anticoagulant
What are the contraindications for nitrates?
- Severe aortic stenosis - heart unable to increase Q through narrowed valve to maintain pressure in now dilated vasculature
- Haemodynamic instability (particularly hypotension)
What are the indications for AT1 blockers?
Same as ACEi (for those who cannot tolerate chronic cough associated with ACEi)
- HTN
- Chronic HF
- IHD
- Diabetic nephropathy and CKD (proteinuria)
What is the mechanism by which beta blockers work?
- Competitive binder of Beta adrenergic receptors; B1 - Heart; B2 - smooth muscle, blood vessels of ariways
- Blockage reduces sympathic drive → reduces Myocardia iscahemia by:
- reducing cardiac contractile force
- increasing perfusion
- Reducing conduction speed
- AF - reduces VT by prolonging AV refractory period
- HTN - reduces BP by reducing renin (acts on B1 receptor in kidney)
What are the CIs for statins?
- Generally well tolerated
- Cautioned in: hepatic failure (eliminated by P450 enzymes), kidney failure (excreted by), and pregnancy (foetal development needs cholesterol)
What are the CIs for K+ sparing diuretics?
- Hyperkalaemia/hyponatraemia
- Severe renal impairment
Cautioned in:
- Hypokalaemia (unpredictable effects)
- Volume depletion
How are beta blockers eliminated?
Hepatic and renally
What are the indications for amiodarone?
- Tachyarrthymias - AF, A. flutter, SVT, VT, VF - ONLY when other theurapetic options are ineffective/not tolerated/inappropriate
What are the SEs of loop duiuretic?
- hypotension/dehydration
- Low electrolyte states e.g. hypocalcaemia, hyponatramia
- Gout - urate retention
- Hearing loss/tinnitus - similar co-trasnporter regulates endolymph in inner ear
What are glyceryl trinitrate and isosorbide mononitrates?
Nitrates
What are the side effects of nitrates?
- Flushing
- Headaches
- Lightheadedness
- Sustained use - intolerance (avoid at night to ensure nitrate free period every day)
What class of drug is bendroflumethiazide?
Thiazide or thiazide like diuretics
What type of drug is Losartan, candesartan and irbesartan?
Angiotensin Receptor blocker (AT1)
When is the best time for statins to be taken?
Evening (work best when food intake is lowest)
What class of drug is aspirin?
Anti-platelet
What are the contraindications for warfarin?
- Immediate risk of haemorrhage (trauma/surgery)
- Pregnancy (1st trimester - teratogenic - cardiac and cranial abnormalities)
Cautioned in hepatic disease - reduced metabolism of drug = increased concentration = increased risk of bleeding
What is the mechansim by which digoxin exerts if effect?
-vely chronotrophic (reduces HR)
+vely inotrophic (increases contractile force)
AF/A Flutter Increases vagal (parasynpathetic) input → reduces AV conduction → reduces vent tachycardia
HF - directly blocks Na+/K+ ATPase pumps → intracell Na+ increases → intracell Ca2+ increases → increased contractile force
What are the SEs of clopidogrel?
- Significant bleeding
- GI upset (dyspepsia, diarrhoea, abdo pain)
- Thrombocytopenia (reduced number and/or function)
What are the CIs for thiazide diuretics?
- Hypo Na/K
- Gout - reduces uric acid excretion → increases urate retention → precipitates acute gout
What is the mechanism by which warfarin works?
Inhibits hepatic production of vitamin K dependent coagulation factors (II, VII, IX, X) and co-factor (Proteins, C, S, Z)
Vitamin K needs to be reduced form for coagulation synthesis - done my vit k epoxide reductase
Warfarin inhibits vit K epoxide reductase
What are the indications for ACEi?
- First/second line for HTN (reduce stroke, MI, death)
- Chronic heart failure - 1st line in improving symptoms/prognosis
- Ischameic heart disease - reduce risk of subsequent attacks
Diabetic nephropathy and CKD with proteinuria (reduces prtoeinuria and progression)
What are the CIs for loop diuretics?
- Hypovolaemia/dehydration/hypotension
Cautioned in
- Hepatic encephalopathy
- Gout (urate retention)
- Hypo-Na+/K+
What are the indications for statins?
- Primary prevention of CV disease - >40 yrs with with 10yr risk of CV disease >20%
- Secondary prevention - 1st line alongside lifestyle changes
- 1st line for hyperlipidaemia e.g. hypercholestraemia etc
What are the possible interactions of AT1 blockers?
- Avoid with K+ elevating drugs (possible hyperkalemia)
- Avoid with other diuretics (massive hypotension)
AT1 + NSAIDs increases = potential renal failure
What are the contraindications for digoxin?
- 2nd degree or complete heart block
- Ventricular arrthymias
Cautioned in:
- Electrolyte disturbance: particularly K+ (digoxin is a competitor of K= so if there is less K+, digoxin will have greater effect → greater risk of digoxin toxicity
- Renal failure - eliminated by kidneys → increased chance of digoxin toxicity
What are the indications for furosemide?
- Acute pulmonary oedema
- Fluid overload states - chronic HF, renal disease (nephrotic syndrome), hepatic failure (cirrhosis)
What are the possible interactions of warfarin?
- Cytochrome P450 inhibitors - reduce metabolism = increased risk of bleeding
- Cytochrome P450 inducers - increased metabolism = increased risk of clot