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ANTIARRÍTMICOS
-Sebastián Cárdenas V
-Jaime Mella R..
DEFINICION
TRATAMIENTO
FRECUENCIA
Extracelular
Intracelular
Na+
Ca2+
K+
Cl-
+20 mV
Ca2+
K+
Na+
K+
Na+
-90 mV
Tiempo
ECG
R
T
P
Q
S
ESTRATEGIA
-50 mV
-65 mV
-75 mV
Pot. Umbral
-85 mV
Pot. Diastólico máx.
Clasificación de los Fármacos
Antiarrítmicos
Grupo I
Grupo II
Grupo III
Grupo IV
QUINIDINA
-ADME
-CONC. TERAPÉUTICAS Y TÓXICAS
-CINCONISMO
-RIESGO DE MUERTE.
-CATEGORÍA C
TRATAMIENTO
A) EMESIS - Not recommended because of the risk of significant dysrhythmias,
seizures, and coma.
B) ACTIVATED CHARCOAL: Administer charcoal as a slurry (240 mL water/30 g
charcoal). Usual dose: 25 to 100 g in adults/adolescents, 25 to 50 g in children (1 to
12 years), and 1 g/kg in infants less than 1 year old.
C) GASTRIC LAVAGE: Consider after ingestion of a potentially life-threatening
amount of poison if it can be performed soon after ingestion (generally within 1
hour). Protect airway by placement in Trendelenburg and left lateral decubitus
position or by endotracheal intubation. Control any seizures first.
CONTRAINDICATIONS: Loss of airway protective reflexes or decreased level of
consciousness in unintubated patients; following ingestion of corrosives;
hydrocarbons (high aspiration potential); patients at risk of hemorrhage or
gastrointestinal perforation; and trivial or non-toxic ingestion.
D) Monitor plasma and serum potassium levels. If refractory dysrhythmia develops,
assess Ca and Mg.
E) Administration of SODIUM BICARBONATE (1 to 2 mEq/kg IV in an adult, or
1/2 to 1 mEq/kg in a child) may decrease toxicity.
F) TORSADES DE POINTES: Hemodynamically unstable patients require electrical
cardioversion. Treat stable patients with magnesium, isoproterenol, and/or atrial
overdrive pacing. Correct electrolyte abnormalities (hypomagnesemia,
hypokalemia, hypocalcemia).
1) MAGNESIUM SULFATE/DOSE: ADULTS: 2 g IV over 1 to 2 min, repeat 2 g
bolus and begin infusion of 0.5 to 1 g/hr if dysrhythmias recur. CHILDREN: 25 to
50 mg/kg diluted to 10 mg/mL; infuse IV over 5 to 15 min.
2) ISOPROTERENOL/DOSE: Correct hypovolemia first. ADULT: 2 to 10
mcg/minute (CHILD: 0.1 to 1 mcg/kg/minute) IV infusion; titrate to heart rate and
rhythm response. Mix 1 mg isoproterenol HCl in 500 mL D5W for a 2 mcg/mL
solution.
3) Avoid class Ia (quinidine, disopyramide, procainamide, aprindine) and most class
III antidysrhythmics (N-acetylprocainamide, sotalol).
G) PHENYTOIN OR LIDOCAINE (type I antiarrhythmics) may be used to control
some types of dysrhythmias. Phenytoin theoretically is preferred as it increases AV
conduction velocity. DO NOT use procainamide or disopyramide.
1) LIDOCAINE: ADULT: LOADING DOSE: 1 to 1.5 mg/kg IV push; for
refractory VT/VF may give an additional bolus of 0.5 to 0.75 mg/kg over 3 to 5
min. Do not exceed 3 mg/kg or 200 to 300 mg over one hour. INFUSION: Once
circulation restored begin infusion of 1 to 4 mg/min. PEDIATRIC: LOADING
DOSE: 1 mg/kg; INFUSION: 20 to 50 mcg/kg/min. Monitor ECG continuously.
H) Initial treatment of bradycardia or heart block should include the use of atropine
and isoproterenol.
1)
Consider temporary pacemaker insertion in patients with refractory bradycardia,
Mobitz II block, or third degree heart block.
I)
1)
HYPOTENSION - Theoretically, pure or predominant alpha agonists such as
norepinephrine or metaraminol may be more effective.
HYPOTENSION: Infuse 10 to 20 mL/kg isotonic fluid. If hypotension persists,
administer dopamine (5 to 20 mcg/kg/min) or norepinephrine (ADULT: begin
infusion at 0.5 to 1 mcg/min; CHILD: begin infusion at 0.1 mcg/kg/min); titrate
to desired response.
J) SEIZURES: Administer a benzodiazepine IV; DIAZEPAM (ADULT: 5 to 10 mg,
repeat every 10 to 15 min as needed. CHILD: 0.2 to 0.5 mg/kg, repeat every 5
min as needed) or LORAZEPAM (ADULT: 2 to 4 mg; CHILD: 0.05 to 0.1
mg/kg).
•
1) Consider phenobarbital if seizures recur after diazepam 30
mg (adults) or 10 mg (children > 5 years).
•
2) Monitor for hypotension, dysrhythmias, respiratory
depression, and need for endotracheal intubation. Evaluate for
hypoglycemia, electrolyte disturbances, hypoxia.
LIDOCAÍNA
CH3
CH3
O
N
NH
CH3
CH3
TRATAMIENTO
A) EMESIS - Contraindicated after oral overdose due to rapid development of
seizures.
B) Ingestion of most of these liquid formulations results in rapid absorption and
gastric decontamination is of limited utility.
C) ACTIVATED CHARCOAL: Administer charcoal as a slurry (240 mL water/30 g
charcoal). Usual dose: 25 to 100 g in adults/adolescents, 25 to 50 g in children (1 to
12 years), and 1 g/kg in infants less than 1 year old.
D) SEIZURES - Administer diazepam IV bolus (DOSE: ADULT: 5 to 10 mg initially
which may be repeated every 15 minutes PRN up to 30 mg. CHILD: 0.25 to 0.4
mg/kg dose up to 10 mg/dose) or lorazepam IV bolus (DOSE: ADULT: 4 to 8 mg;
CHILD: 0.05 to 0.1 mg/kg).
1) If seizures are uncontrollable or recur, give phenobarbital.
2) Phenytoin may worsen or precipitate cardiac arrhythmias from local
anesthetics and should be avoided.
E) COMA/RESPIRATION DEPRESSION - Protect the airway with an
endotracheal tube and assist ventilation as necessary.
F) BRADYCARDIA/BRADYARRHYTHMIAS - If symptomatic and heart rate is
less than 60, consider administration of atropine 15 mcg/kg (up to 0.4 to 0.6
mg/dose) IV, IM or subcutaneously.
G)
HYPOTENSION: Infuse 10 to 20 mL/kg isotonic fluid. If hypotension
persists, administer dopamine (5 to 20 mcg/kg/min) or norepinephrine
(ADULT: begin infusion at 0.5 to 1 mcg/min; CHILD: begin infusion at
0.1 mcg/kg/min); titrate to desired response.
H)
ACIDOSIS - Severe metabolic acidosis (pH <7.1) should be corrected
with IV sodium bicarbonate. Respiratory acidosis should be treated by
assisted ventilation. Monitor serum bicarbonate and arterial blood gases to
guide therapy.
I)
METHEMOGLOBINEMIA: Administer 1 to 2 mg/kg of 1% methylene
blue slowly IV in symptomatic patients. Additional doses may be required.
J)
ELIMINATION ENHANCEMENT - Hemodialysis, exchange
transfusion, AV hemofiltration and forced diuresis have not been shown to
increase clearance substantially. Urinary acidification is NOT
recommended.
PROPAFENONA
O
OH
O
NH
CH3
TRATAMIENTO
A) In overdose ventricular dysrhythmias and seizures have been reported. Patients
should be monitored for ventricular tachydysrhythmias and provided with supportive
care. No specific antidote exists.
B) EMESIS: Ipecac-induced emesis is not recommended because of the potential for
seizures.
C) GASTRIC LAVAGE: Consider after ingestion of a potentially life-threatening
amount of poison if it can be performed soon after ingestion (generally within 1 hour).
Protect airway by placement in Trendelenburg and left lateral decubitus position or by
endotracheal intubation. Control any seizures first.
1) CONTRAINDICATIONS: Loss of airway protective reflexes or decreased level of
consciousness in unintubated patients; following ingestion of corrosives; hydrocarbons
(high aspiration potential); patients at risk of hemorrhage or gastrointestinal perforation;
and trivial or non-toxic ingestion.
D) ACTIVATED CHARCOAL: Administer charcoal as a slurry (240 mL water/30 g
charcoal). Usual dose: 25 to 100 g in adults/adolescents, 25 to 50 g in children (1 to 12
years), and 1 g/kg in infants less than 1 year old.
E) VENTRICULAR DYSRHYTHMIAS - Institute continuous cardiac monitoring,
obtain an ECG, and administer oxygen. Evaluate for hypoxia, acidosis, and electrolyte
disorders. Intravenous bicarbonate may be useful in patients with QRS widening or
ventricular dsyrhythmias. Administer 1 to 2 mEq/kg bolus and repeat as needed.
Monitor ECG and arterial blood gases; maintain pH 7.45 to 7.55.
1) If unresponsive to bicarbonate, lidocaine is generally the first line agent. Consider
bretylium and/or phenytoin if dysrhythmias persist.
F) HYPOTENSION: Infuse 10 to 20 mL/kg isotonic fluid. If hypotension persists,
administer dopamine (5 to 20 mcg/kg/min) or norepinephrine (ADULT: begin
infusion at 0.5 to 1 mcg/min; CHILD: begin infusion at 0.1 mcg/kg/min); titrate to
desired response.
G) SEIZURES - Administer a benzodiazepine IV; DIAZEPAM (ADULT: 5 to 10 mg,
repeat every 10 to 15 minutes as needed. CHILD: 0.2 to 0.5 mg/kg, repeat every 5
minutes as needed) or LORAZEPAM (ADULT: 4 to 8 mg; CHILD: 0.05 to 0.1
mg/kg).
1) Consider phenobarbital if seizures are uncontrollable or recur after diazepam 30 mg
(adults) or 10 mg (children > 5 years).
2) Monitor for hypotension, dysrhythmias, respiratory depression and the need for
endotracheal intubation. 3) Evaluate for hypoglycemia, electrolyte disturbances, and
hypoxia.
4) Phenytoin is generally NOT recommended as it may exacerbate cardiotoxicity.
H) ATROPINE: ADULT DOSE: BRADYCARDIA: 0.5 to 1 mg IV every 5
min. ASYSTOLE: 1 mg IV every 5 min. Maximum total dose 3 mg or 0.04
mg/kg. Minimum single dose 0.5 mg. PEDIATRIC DOSE: 0.02 mg/kg IV
repeat every 5 min, minimum single dose 0.1 mg; maximum single dose child
0.5 mg, adolescent 1 mg; maximum total dose 1 mg child, 2 mg adolescent.
AHORA CONTINÚA CÁRDENAS...
ANTIARRÍTMICOS CLASE
II
AMIODARONA
LD50=254mg/kg ratones i.p., LD50=885mg/kg ratas i.p.
BDoral=29-100%, Vd=65.8L/kg, t1/2=9-44días
SOTALOL
SOTALOL
• Torsades de pointes
• Prolongado intervalo QT
• Fibrilación ventricular
• Asístole ventricular
ANTIARRÍTMICOS CLASE
III
PROPRANOLOL
RECEPTORES BETA
β1
β2
β3
TOXICOLOGÍA GENERAL
•
•
•
•
•
Liposolubilidad
Actividad estabilizante de membrana
Actividad simpaticomimética intrínseca
Metabolismo
Cardioselectividad
ANTIARRÍTMICOS CLASE
IV
ANTIARRÍTMICOS CLASE IV
Verapamilo
TOXICOLOGÍA GENERAL
•
•
•
•
Efectos cardiovasculares
Efectos respiratorios
Efectos sobre SNC
Otros
Fármacos
Exposición letal
mínima(g)
Amiodarona
Propranolol
Exposición máxima
tolerada(g)
8
2.06-9.6
Atenolol
2-3
1-1.8
Metoprolol
7.5-10
4.84
Verapamilo
4.16
16
EMBARAZO
Droga
Categoría
Amiodarona
C
Propanolol
C
Atenolol
D
Metoprolol
C
Verapamilo
C
TRATAMIENTO
• Apoyo cardiorespiratorio de funciones
afectadas
• Tratamiento sintomático
• Monitoreo: electrolitos, función renal,
glicemia, presión arterial, ECG.
• Ingestión oral: lavado gástrico, carbón
activado.
CONCLUSIÓN PEROGRULLESCA
TODOS
LOS
ANTIARRÍTMICOS
PRODUCEN
ARRITMIAS
RESUMEN BIBLIOGRÁFICO
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§
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§
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§
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§
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§
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§
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§
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§
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§
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§
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“La realidad tiene limites; la estupidez
no”.
Napoleón