Antidysrhythmics Flashcards
Adenosine (Adenocard)
Type: Antidysrhythmic
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MOA:
Short-acting drug that slows conduction through the AV node; Restore sinus rhythm in patients with SVT and Terminates regular tachycardias caused by reentrant AV nodal pathways
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Indications: First-line drug for most forms of stable, regular, narrow-complex SVT | Can be considered for marrow-complex reentry tachycardia while preparing for cardioversion | Can be used diagnostically for stable, regular, monomorphic wide-complex tachycardia
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Contraindications: Known hypersensitivity | Second- or third-degree AV block or sick sinus syndrome or other sinus node disease | Poison- or drug-induced tachycardia | Use with caution in patients with a history of seizure disorder | May induce bronchospasm in a patient with bronchoconstrictive or bronchospastic lung disease (ex: asthma and COPD)
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Adverse Reactions: Generally transient and of short duration | Flushing, sweating, dizziness, nervousness, paresthesia, hypotension, feeling of impending doom, severe bronchospasm | A brief period of most any dysrhythmia (like asystole) can occur during pharmacologic conversion
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Drug Interactions: Additive effects are possible if used in combination with beta blockers | Methylxanthines (like caffine and theophylline-like drugs) block the actions of adenosine | Dipyridamole (Persantine) potentiates the effect | Carbamazepine (Tegretol) may potentiate the AV node blocking effect | Nicotine can enhance the cardiovascular effects | An increase in angina-like chest discomfort or heart rate | A decrease in BP may be observed
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Dosages:
Adult.
6-mg rapid IV/IO bolus over 1 to 3 second followed by a 10-mL saline flush; Additional 12-mg dose if needed after 1 to 2 minutes over the same time frame; Maximum total dosage is 30 mg
Paediatric.
Initial dose 0.1 mg/kg (max first dose of 6mg) rapid IV/IO push over 1 to 3 seconds followed by a 5- to 10-mL saline flush; Second dose 0.2 mg/kg (max second dose of 12mg) rapid IV/IO push followed by a 5- to 10-mL saline flush
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Duration: Onset: Seconds | Peak effect: Seconds | Duration: 10 seconds
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Special Conditions: Pregnancy safety: Category C | Monitor the ECG and record a rhythm, strip during administration | Ineffective in converting AF, atrial flutter, or VT | Should NOT be administered for hemodynamically unstable, irregularly irregular, or polymorphic wide-complex tachycardias
Amiodarone (Cordarone, Pacerone)
Type: Antidysrhythmic (Class III)
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MOA:
Blocks sodium, potassium, and calcium channels; Prolongs the action potential’s duration and Delays repolarization; Decreases AV conduction and sinoatrial (SA) node function
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Indications: Cardiac arrest resulting from VF or pulseless VT after CPR, defibrillation, and epinephrine | Stable, regular narrow-complex tachycardia if the rhythm persists despite vagal maneuvers or adenosine or the tachycardia is recurrent | To control the ventricular rate in AF with a rapid ventricular response without preexcitation | Stable wide-complex tachycardia | Stable monomorphic VT | Polymorphic VT with a normal QT interval
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Contraindications: Known hypersensitivity | Iodine hypersensitivity | Cardiogenic shock | Second- of third-degree AV block | Sick sinus syndrome or other sinuse node disease (unless a functioning artificial pacemaker is present)
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Adverse Reactions: Hypotension | Heart failure | Worsening of dysrhythmias | Prolonged QT interval | Bradycardia | AV block | Dizziness | Fatigue | Cough | Progressive dyspnea | N/V | Burning at the IV site | Stevens-Johnson syndrome
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Drug Interactions: May increase the effects of digoxin, disopyramide, fentanyl, lidocaine, procainamide, quinidine, or warfarin | Cimetidine may increase amiodarone levels | Use with beta blockers or calcium channel blockers may potentiate bradycardia, sinus arrest, and AV blocks | Persistent use of echinacea can potentiate amiodarone’s hepatotoxic effects
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Dosages:
Adult.
Initial dose 300 mg IV/IO push ; Second dose 150 mg IV/IO push ; Loading dose 150 mg IV/IO over 10 minutes ; Max cumulative dose of 2.2 g IV/IO per 24 hours
Paediatric.
Refractory VF/pulseless VT: 5 mg/kg IV/IO bolus ; can repeat if needed to max cumulative dose of 15mg/kg IV per 24 hours (2.2g in adolescents per 24 hours) ; Max single dose of 300mg.
Poor perfusing ventricular or atrial sysrhythmias: loading dose 5mg/kg IV/IO over 20 to 60 minutes (max single dose of 300mg) ; can repeat if needed to max cumulative dose of 15mg/kg IV per 24 hours (2.2g in adolescents per 24 hours)
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Duration: Onset: 2 hours | Peak effect: 3 to 7 hours | Duration: Variabled
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Special Conditions: Pregnancy safety: Category D ; may cause fetal death ; Lactating women should not breastfeed following use | May worsen or precipitate new dysrhythmias | Monitor for hypotension and increasing PR and QT intervals | Dosage may change per the most current International Liaison Committee on Resuscitation (ILCOR) recommendations
Diltiazem (Cardizem, Dilacor, Diltiaz)
Type: Calcium channel blocker, Antidysrhythmic (Class IV), Antianginal agent
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MOA:
Inhibits extracellular calcium ion influx across membranes of myocardial cells and vascular smooth muscle cells, resulting in inhibition of cardiac and vascular smooth muscle coontraction and therby dilating the main coronary and sestemic arteries | No effect on serum calcium concentrations | Substantial inhibitory effects on the cardiac conduction system, acting principally at the AV node, w/ some effects at the SA node | Less-negative inotropic effects than verapamil
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Indications: Stable narrow-QRS tachycardia; if Rhythm persists despite vagal maneuvers or administration of adenosine, or if the tachycardia is recurrent | To control the ventricular rate in patients with AF or atrial flutter without preexcitation
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Contraindications: Known hypersensitivity | Hypotension | Cardiogenic shock | Wide-complex tachycardia (may lead to hemodynamic deterioration and VF) | Second- or third-degree AV block | Sick sinus syndrome or other sinus node disease | Poison- or drug-induced tachycardia | AF or atrial flutter associated with an accessory bypass tract (ex: Wolff-Parkinson-White syndrome or Lown-Ganong-Levine syndrome) | Avoid use in patients with left ventricular systolic dysfunction or decompensated heart failure | Use with extreme caution in patients taking oral beta blockers
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Adverse Reactions: Dizziness | Weakness | Headache | Dyspnea | Dysrhythmias including cardiac arrest | Heart failure | Peripheral edema | Hypotension | Syncope | Chest pain | N/V | Dry mouth
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Drug Interactions: Use with caution in patients taking medications that affect cardiac contractility | Simultaneous use with IV beta blockers can result in decreased cardiac contractility, bradycardia (including AV blocks), and hypotension | Increased risk of sudden cardiac death when given concurrently with erythromycin
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Dosages:
Adult.
Initial dose: 15 to 20 mg (0.25 mg/kg) IV/IO slowly over 2 minutes ; After 15 minutes: a second bolus of 20 to 25 mg (0.35 mg/kg) IV/IO can be given slowly over 2 minutes
Patients older than age 65: require a maximum initial dose of 10 mg IV/IO and second dose of 20 mg IV/IO ; Maintenance infusion: 5 to 15 mg/h titrated to a physiologically appropriate heart rate
Paediatric. Not recommended
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Duration: Onset: 2 to 5 minutes | Peak effect: Usually within 7 minutes | Duration: 1 to 3 hours
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Special Conditions: Pregnancy safety: Category C | Dysrhythmias may be observed during pharmacologic conversion | Carefully monitor BP and EKG before, during, and after administration
Lidocaine HCl (Xylocaine)
Type: Antidysrhythmic (Class Ib), Anesthetic
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MOA:
Cardiac: Inhibits recovery after repolarization, thereby inhibiting recovery after repolarization, and decreasing myocardial excitability and conduction velocity | Local anesthetic: Inhibits ion transport across the neuronal membrane, blocking conduciton of normal nerve impulses | RSI: May decreases ICP response during laryngoscopy
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Indications: Alternative to amiodarone in patients with cardiac arrest from: VT, VF ; Stable monomorphic VT ; or Stable polymorphic VT with normal baseline QT interval when ischemia is treated with electrolyte balance is corrected | Can be used for stable polymorphic VT with baseline QT interval prolongation if TdP is suspected | Can be used as a local anesthetic for various procedures
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Contraindications: Hypersensitivity to lidocaine or amide-type local anesthetics, second- or third-degree AV block in the absence of artifical pacemaker, Stokes-Adams syndrome, wide-complex ventricular escape beats w/ bradycardia, Wolff-Parkinson-White Syndrome | Prophylactic use in AMI is contraindicated
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Adverse Reactions: Drowsiness | Confusion | Seizures | Slurred speech | Hypotension | Dysrhythmias | Cardiac arrest | Nausea/vomiting
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Drug Interactions: Apnea induced with succinylcholine may be prolonged by high doses of lidocaine | Cardiac depression may occur in conjunction with administration of IV phenytoin | Procainamide may exacerbate the CNS effects | Metabolic clearance is decreased in patients with liver disease and patients taking beta blockers
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Dosages:
Adult.
Cardiac arrest (pulseless VT/VF): Initial does: 1 to 1.5 mg/kg IV/IO. Repeat dose: 0.5 to 0.75 mg/kg IV/IO repeated in 5 to 10 minutes. Maximum total dose: 3 mg/k.
Maintenance infusion: 1 to 4 mg/min
Stable VT and stable regular wide-complex tachycardia: Initial does: 1 to 1.5 mg/kg IV/IO. Repeat dose: 0.5 to 0.75 mg/kg IV/IO repeated in 5 to 10 minutes. Maximum total dose: 3 mg/kg.
Maintenance infusion: 1 to 4 mg/min
Local anesthetic dose varies depending on the procedure and anatomic location. If IO on a conscious pt, consider 0.5 mg/kg of lidocaine 0.1 mg/mL slow push through the IO to max of 40mg to mitigate pain of IO med administration
Paediatric.
IV/IO dose: 1 mg/kg IV/IO push
Maintenance IV/IO infusion: 20 to 50 mcg/kg/mins. Repeat bolus dose if infusion started more than 15 minutes after initial bolus dose
ET dose: 2 to 3 mg/kg
RSI: 1 to 2 mg/kg IV/IO
Local anesthetic dose varies depending on the procedure and anatomic location
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Duration: Onset: 1 to 5 minutes | Peak effect: 5 to 10 minutes | Duration: 10 to 20 minutes
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Special Conditions: Pregnancy safety: Category B | Reduce the maintenance infusion in the presence of impaired liver function or left ventricular dysfunction | Discontinue the infusion immediately if signs of toxicity develop
Magnesium sulfate
Type: Electrolyte, Class V antidysrhythmic
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MOA:
Depresses the CNS, blocks peripheral neuromuscular transmission, and produces anticonvulsant effects | Decreases the amount of acetylcholine released at the endplate by motor nerve impulses, slows the rate of SA node impulse formation in the myocardium, and prolongs conduction time | Promotes calcium, potassium, and sodium movement in and out of cells and stabilizes excitable membranes | Induces uterine relaxation | Can cause bronchodilation after beta agonists and anticholinergics have been administered
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Indications: Management of TdP | Severe bronchoconstriction with impending respiratory failure | Seizure during the third trimester of pregnancy or in the postpartum patient
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Contraindications: Known hypersensitivity, heart block, myocardial damage, diabetic coma, hypermagnesemia, hypercalcemia | Use with caution in patients with known renal insufficiency
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Adverse Reactions: Drowsiness | CNS depression | Respiratory depression/tract paralysis | Vasodilation | Possible hypotension and bradycardia with rapid administration | Decreased deep tendon reflexes
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Drug Interactions: May enhance the effects of other CNS depressants | Serious changes in overall cardiac function may occur with cardiac glycosides
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Dosages:
Adult.
Severe hypertension lasting more than 15 minutes with associated preeclampsia symptoms: Give 4 g of a 20% solution IV/IO over 20 minutes, followed by 1 g/h IV/IO, if available
Seizure activity associated with pregnancy greater than 20 weeks’ gestation: Give 4 g of a 50% solution IV/IO over 10 to 20 minutes, followed by 1 g/h IV/IO, if available
Cardiac arrest due to hypomagnesemia or TdP: Give 1 to 2 g IV/IO
TdP with pulse or AMI with hypomagnesemia: Loading dose of 1 to 2 g in 50 to 100 mL of D5W or NS over 5 to 60 minutes IV. Follow with 0.5 to 1 g/h IV
Status asthmaticus: 1 to 2 g IV over 15 to 30 minutes
Severe bronchoconstriction/impending respiratory failure: 40 mg/kg IV over 10 to 15 minutes (2 g maximum)
Paediatric.
Pulseless VT with TdP: 25 to 50 mg/kg IV/IO bolus of a 50% solution (2 g maximum)
TdP with pulses or hypomagnesemia: 25 to 50 mg/kg IV/IO of a 50% solution over 10 to 20 minutes (2 g maximum)
Status asthmaticus: 25 to 50 mg/kg IV/IO of a 50% solution over 15 to 30 minutes (2 g maximum)
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Duration: Onset: Immediate | Peak effect: Variable | Duration: 30 minutes
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Special Conditions: Pregnancy safety: Category D ; Due to confirmed evidence of human fetal risk, must be used cautiously, although administration may be justified | To treat magnesium toxicity: Stop the infusion, Give calcium gluconate 1 g IV in cases of impending respiratory arrest, Support the patient’s ventilatory effort | Do NOT abbreviate magnesium sulfate to avoid confusion with morphine sulfate
Procainamide Hydrochloride (Pronestyl)
Type: Class Ia antidysrhythmic
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MOA:
Inhibits recovery after repolarization, resulting in decreased myocardial excitability and conduction velocity | Direct membrane depressant that decreases conduction velocity, prolongs the refractory period, decreases automaticity, and reduces repolarization abnormalities
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Indications: Stable monomorphic VT with normal QT interval | Reentry SVT uncontrolled by vagal maneuvers and adenosine if BP is stable | Stable wide-complex tachycardia of unknown origin | AF with a rapid ventricular rate in patients with Wolff-Parkinson-White syndrome
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Contraindications: Known hypersensitivity to procainamide or other ingredients | TdP | Second- and third-degree heart AV block | Systemic lupus erythematosus | Preexisting QT prolongation | Digitalis toxicity | TCA overdose | Administer with caution to patients with: Asthma or digitalis-induced dysrhythmias; Myasthenia gravis; Cardiac, hepatic, or renal insufficiency
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Adverse Reactions: Can induce or worsen cardiac dysrhythmias | Anorexia | N/V | Confusion | Seizures | Severe hypotension | Widening of PR, QRS, and QT intervals
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Drug Interactions: Additive effect with other antidysrhythmic agents | Use with beta agonists may be associated with adverse cardiovascular effects, including QT interval prolongation
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Dosages:
Adult.
Recurrent VF/pulseless VT: 20 mg/min slow IV infusion until the dysrhythmia is suppressed ; Maximum total dose: 17 mg/kg
In urgent situations: up to 40 mg/min may be administered, up to a total dose of 17 mg/kg
Other indications: 20 mg/min slow IV infusion until dysrhythmia suppression, hypotension, QRS widens by more than 50% of its pretreatment width, or a maximum dose has been given
Maintenance infusion: 1 to 4 mg/min (diluted in D5W or NS);
(In the presence of cardiac, hepatic, or renal dysfunction, reduce the maximum total dose to 12 mg/kg and the maintenance infusion to 1 to 2 mg/min)
Paediatric.
NOT recommended in the prehospital setting
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Duration: Onset: 10 to 30 minutes | Peak effect: Variable | Duration: 3 to 6 hours
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Special Conditions: Pregnancy safety: Category C | Hypotension may occur with rapid infusion
Verapamil Hydrochloride (Isoptin, Calan)
Type: Calcium channel blocker
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MOA:
Slows AV node conduction, Shortens the refractory period of accessory pathways, and Acts as a negative inotrope and vasodilator
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Indications: Stable narrow-QRS tachycardia if the rhythm persists despite vagal maneuvers or adenosine or if the tachycardia is recurrent | To control the ventricular rate in patients with AF or atrial flutter without preexcitation
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Contraindications: Known hypersensitivity | Wolff-Parkinson-White syndrome, Lown-Ganong-Levine syndrome | Second- or third-degree AV block, sick sinus syndrome, or other sinus node disease without an artificial pacemaker present | Hypotension, cardiogenic shock, severe left ventricular dysfunction, wide-complex tachycardias | Children younger than age 12 months | Use with extreme caution in patients receiving oral beta blockers
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Adverse Reactions: Dizziness, headache, dysrhythmias, nausea/vomiting | Can decrease myocardial contractility
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Drug Interactions: Increases the serum concentration of digoxin | Simultaneous administration with IV beta blockers can produce severe hypotension | Antihypertensives may potentiate the hypotensive effects | May potentiate the activity of depolarizing and nondepolarizing neuromuscular blocking agents | Increased risk of sudden cardiac death when given concurrently with erythromycin | St. John’s wort can reduce its effectiveness
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Dosages:
Adult.
2.5 to 5 mg IV bolus over 2 minutes (3 minutes in older patients) ; Repeat dose of 5 to 10 mg may be given every 15 to 30 minutes to a maximum total dose of 20 mg
Alternative dosing: 5 mg IV bolus every 15 minutes to a total dose of 30 mg
Paediatric.
Consult medical direction
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Duration: Onset: 2 to 5 minutes | Peak effect: Variable | Duration: 10 to 20 minutes
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Special Conditions: Pregnancy safety: Category C | Carefully monitor BP, heart rate, and ECG before, during, and after administration | AV block or asystole may occur because of slowed AV conduction
