Anti-arrhythmics (FETT)

ATROPINE

ADENOSINE

AMIODARONE

Flecainide

Tertiary amines

Lipophilic (good oral bioavailability and CNS penetration)

• ↑ Heart rate

• ↓ Secretions of exocrine glands

• ↓ Tone and motility of smooth muscles (i.e., ↓ urgency in cystitis)

• ↓ Cholinergic overactivity in CNS

• Mydriasis and cycloplegia

• First drug of choice in unstable (symptomatic) sinus bradycardia (IV)

• Premedication: prior to intubation to decrease salivary, respiratory, and gastric secretions

• Ophthalmology: uveitis

• Urinary urgency, urge incontinence, urinary frequency and/or nocturia (symptoms resulting from, e.g., overactive bladder syndrome)

• Antidote for anticholinesterase poisoning: atropine reverses the muscarinic effects of cholinergic poisoning (e.g., bronchoconstriction) but does not reverse the nicotinic effects (e.g., muscle weakness, paralysis).

• Scorpion stings

• Dry mouth and sore throat

• ↓ Respiratory tract secretions

• Hyperthermia and warm, dry skin

• Tachycardia

• Gastroesophageal reflux

• Obstipation or ileus

• Impaired micturition/urinary retention

• Vasodilatation and flush

• Mydriasis and photophobia

• Blurred vision

• Excitement, agitation, and hallucinations with the use of lipophilic parasympatholytics (e.g., atropine), especially in elderly patients

• Confusion, disorientation

• Coma, seizure, and rarely death

• Respiratory distress

• Tachyarrhythmias

• Heart failure

• Myocardial infarction

• Hyperthyroidism

• Hiatal hernia associated with reflux esophagitis

• Ulcerative colitis

• Paralytic ileus

• Obstructive disease of the gastrointestinal tract (e.g., achalasia, pyloric stenosis or duodenal stenosis)

• Obstructive uropathy (e.g., benign prostatic hyperplasia, urinary retention)

• Narrow angle glaucoma

• Myasthenia gravis

• Anticholinergic agents block the neurotransmitter acetylcholine in the central and peripheral nervous system.

  • Muscarinic antagonists: inhibit the effect of acetylcholine on muscarinic receptors (the majority of anticholinergic drugs)

  • Antinicotinic agents: inhibit the effects of acetylcholine on nicotinic receptors (mostly skeletal muscle relaxants).

activates Gi protein → inhibition of adenylate cyclase → ↓ cAMP → deactivation of L-type Ca2+ channels and activation of K+ channels → ↓ Ca2+ and ↑ K+ efflux → hyperpolarization → transient AV node block (short-acting, ∼ 15 seconds) → acute termination of supraventricular tachycardia

• Diagnosis and termination of certain forms of paroxysmal supraventricular tachycardias (e.g., AVNRT and orthodromic AVRT)

• Diagnosis of underlying AFib in supraventricular tachyarrhythmias

• Pharmacological stress test in myocardial perfusion scintigraphy

• Rapid bolus IV (very short half-life: < 10 seconds)

• May be administered repeatedly if the previous dose was unsuccessful

• Chest pain, flushing, hypotension, bronchospasm

• Sense of impending doom

• AV block, asystole

• Pre-excitation syndromes: antidromic AVRT, WPW

• AV block

• Asthma

Theophylline and caffeine weaken the effects of adenosine because they are adenosine receptor antagonists.

antiarrhythmic effect via blockage of voltage-gated potassium channels → prolonged repolarization of the cardiac action potential

inhibits β-receptors and sodium and calcium channels → decreases conduction through the AV and sinus node

only antiarrhythmic agent with (almost) no negative inotropic effect → use in patients with reduced EF

• Acute treatment (IV administration)

  • Second-line therapy for patients with ventricular tachycardia (VT) who are hemodynamically stable

  • Persistent VT after defibrillation

  • Pulseless ventricular fibrillation

  • Supraventricular tachycardia in patients with cardiac failure (LVEF < 40%)

• Long-term treatment (oral administration)

  • Rhythm control in refractory symptomatic atrial fibrillation (supraventricular arrhythmia) and underlying heart disease → restoration and maintenance of sinus rhythm

• Severe sinus node dysfunction with marked sinus bradycardia

• Second- and third-degree heart block (except in patients with a functioning pacemaker)

• Hyperthyroidism and hypothyroidism

• Known allergy to iodine

• Pre-existing lung disease

• Amiodarone is an inhibitor of cytochrome P450 enzymes (see principles of pharmacology) → reduced clearance of the following drugs:

  • Warfarin (risk of bleeding!)

  • Simvastatin (increased risk of rhabdomyolysis)

  • Digoxin

  • Cyclosporine

  • Flecainide, procainamide, quinidine

  • Sildenafil

Class III -> potassium channel blockers

BUT: Has also I, II and IV properties, lipophilic!!!

Class IC antiarrhytmics —> Fast sodium channel blockers

• Strong blockage of Na+ channels (slow association/dissociation) → QRS prolongation

• No to minimal effect on AP duration (no shift)

• Slow conduction velocity

• Extend duration of effective refractory period in both AV node and accessory tracts

• ERP unaffected in cardiac Purkinje cells and ventricular myocardium

• PSVT

• AFib (cardioversion)

• Atrial flutter

• Last resort in refractory VT

• Proarrhythmogenic: contraindicated following myocardial infarction

• Possible QT prolongation due to increased QRS duration