Angina, Cardiac Arrest and Arrhythmias Flashcards
Give 2 examples of calcium channel blockers and 2 indications for their use:
- amlodipine, nifedipine, diltiazem, verapamil
- hypertension rx - to reduce risk of stoke, MI and death
- stable angina - symptom control
- Supraventricular arrhythmia rx - control heart rate (diltiazem, verapamil)
MOA of CCBs
- decrease Ca2+ ion entry into vascular and cardiac cells, reducing intracellular calcium concentration
- this causes…
- effect on inotropy and conduction?
- overall these together reduce ___ so reduces ..
- causes relaxation and vasodilation in arterial smooth muscle, lowering arterial pressure
- in heart, CCBs reduce myocardial contractility
- they supress cardiac conduction (esp across AVN) –> slowing ventricular rate
- together, reduces afterload so reduces myocardial O2 demand - preventing angina
CCBS can be
- dihydropyridines: relatively selective for the vasculature e.g. ____ and ___
- non-dihyropyridines: more selective for the heart, most cardioselective CCB is ___
- dihydropyridines: e.g. amlodipine and nifedipine
- non-dihyropyridines: cardioselective = verapamil
-Amlodipine and nifedipine (CCBs): name 2 SEs caused by vasodilation and compensatory tachycardia
- ankle swelling
- flushing
- headache
- palpitations
Verapamil (CCB) commonly causes ______ less often can cause: ….. (due to effects on heart)
Therefore in who should Verapamil be used with caution, give 2 e.gs?
- constipation
- bradycardia, heart block, heart failure
- Caution: pts with poor LV function (precipitates/worsens HF) and
- people with AV nodal conduction delay (can provoke complete heart block)
-Amlodipine and nifedipine (CCBs): name 2 CIs
(one relates to the vasodilation causing a reflex in contractility and tachycardia, which increases the __ ___)
(other relates to risk of provoking collapse in pts with this pathology)
CI: UNSTABLE ANGINA (increases O2 demand)
SEVERE AORTIC STENOSIS
-Non-dihydropyrididine CCBs e.g. verapail, diltiazem, should not be prescribed with _____ except under specialist supervision as both drug classes are negatively ionotropic and chronotropic so together can cause: HF, bradycardia and asystole
-B-BLOCKERS
Rough dosages for CCBs
- amlodipine for HT e.g. ___ mg orally daily
- diltiazem for angina e.g. ___mg orally 12-hrly
- verapamil for SV arrhythmias e.g. ___mg orally 8-hrly
- amlodipine 5-10mg for HT
- diltiazem 90mg for angina
- verapamil 40-120mg for SV arrhythmias
Amiodarone is indicated in the treatment of several _______ such as:
(only when other therapeutic options-drugs/electrical cardioversion are ineffective)
-tachyarrhythmias e.g. AF. atrial flutter, SVT, VT, refractory VF
Amiodarone MOA:
-effect on myocardial cells is: blockade of..
-so therapeutically in the following can…
AF:
SVT AVNRT:
VT/VF:
- blockades Na+, Ca2+ and K+ channels and alpha & beta adrenergic receptors
- this reduces spontaneous depolarisation, slows conduction velocity and increases refractiveness inc. in the AVN
- so it can reduce ventricular rate in AF/atrial flutter
- can increase chance of conversion and maintenance of sinus rhythm
- in SVT AVNRT can break the circuit and restore sinus rhythm
- can treat and prevent VT and improves chance of successful defibrillation in refractory VF
3 Amiodarone SEs
NB: amIODarone
- pneumonitis
- bradycardia, AV block
- hepatitis
- photosensitivity and grey discolouration of skin
- due to IODine content can –> thyroid abnormalities
(NB: half life is very long, months to clear)
Avoid amiodarone if possible in what 2 pt groups (based on MOA/SEs)
- severe hypotension
- heart block
- active thyroid disease
Amiodarone interacts with very many drugs
Name 2 that in can increase the plasma concentration of which increases risk of bradycardia, AV block and heart failure…
- digoxin
- diltiazem (CCB)
- verapamil (CCB)
- so half the dose of these drugs if amiodarone is started
In ALS algorithm, immediately after the 3rd shock in cardiac arrest with VF or pulseless VT, Amiodarone is given followed by 20ml 0.9% sodium chloride or 5% glucose as a flush. What is the dose of Amiodarone given?
-300mg IV (bolus dose in pre-filled syringe)
Why in a setting outside cardiac arrest if continuous/repeated IV infusions of amiodarone are anticipated should it be given in a central line? What is the risk of peripheral IV administration?
-Can cause significant phlebitis peripherally
2 indications for Digoxin prescription:
- AF and atrial flutter to reduce the ventricular rate (but a B-blocker or non-dihydropyridine CCB is often more effective)
- in severe HF: for pts already taking an ACEi, B-blocker, and an Aldosterone antagonist/ARB
Digoxin MOA
-effect on HR and contractility? How is is useful in AF and how does it help in HF - different aspects
- negatively chronotropic
- positively ionotropic
- increases vagal parasympathetic tone , reduces conduction at AVN, reducing ventricular rate in AF/AFlutter
- in HF: inhibits Na+/K+ ATPase so Na+ accumulates in cell, as cell extrusion of Ca2+ requires low intracellular Na+ concs, elevated Na+ conc causes calcium to accumulate in cell so increases contractile force.
3 adverse effects of Digoxin therapy:
- bradycardia
- GI disturbance
- rash
- diziness
- visual disturbances (blurred or yellow vision)
- pro-arrhythmic in digoxin toxicity (!)
2 Contraindications for use of Digoxin and 2 cautions for its use:
-CI: 2ND DEGREE HEART BLOCK
-CI: INTERMITTENT COMPLETE HEART BLOCK
-CI: PTS W/AT RISK OF VENTRICULAR ARRYTHMIAS
Caution: reduce dose in renal failure (is eliminated renally)
Caution: hypoK+, hypoMg2+ and hyperCa2+ increase the risk of digoxin toxicity
By what mechanism do some diuretics increase the risk of digoxin toxicity? Name 1 other drug that increases plasma conc of digoxin so increases risk of toxicity?
- loop and thiazides can cause hypokalaemia, as result when K+ is low, competition with K+ to bind to Na/K+ ATPase is low so effects of Digoxin are enhanced
- Amiodarone, CCBs, Spironolactone and Quinine can increase plasma conc of Digoxin
What ECG change may be seen with therapeutic levels of Digoxin therapy?
-ST-segment depression, reverse tick sign on ECG
expected effect, doesn’t signify toxicity
-Atropine, hyoscine butylbromide (buscopan) and glycopyrronium are all medications belonging to the class “______ “
give 1 cardio and 1 GI indication for their use.
Anti-muscarinics
- bradycardia
- IBS (anti-spasmodic)
- in care of dying patients to reduce copious respiratory secretions
Anti-muscarinics antagonise the rest and digest effects therefore name 3 SEs associated with their use?
- tachycardia, dry mouth, constipation
- reduce detrusor activity so –> urinary retention in BPH pts
- blurred vision
- drowsiness and confusion
Pts susceptible to ___-__ ___ should not have anti-muscarinics as they can precipitate a rise in ___. And avoid in pts at risk of ____
- acute-angle glaucoma
- rise in ICP
- arrhythmias
