1.Anti-arrhythmic drugs classification
Class I: membrane inhibitors, mainly reduce the permeability of cardiomyocytes to Na, so that the degree and amplitude of phase 0 depolarization is reduced, thus slowing down conduction, while prolonging the effective response period (ERP) of fast response fibers and reducing the slope of phase 4 depolarization, thus reducing autoregulation. There are three subclasses: Class IA, Class IB and Class IC.
Class II: β-adrenergic receptor blockers, mainly by reducing or blocking the sympathetic nerve action on the heart, inhibit the 4-phase auto-depolarization rate and prolong the AV node conduction time. Zhang Guoliang, Department of Geriatrics, Yuncheng Central Hospital
Class III: The main electrophysiological effect is to prolong the action potential interval (APD) ERP by delaying the repolarization time.
Class IV: calcium channel blockers, mainly by blocking the opening of slow Ca++ channels, inhibit the late O-phase depolarization and 2-phase repolarization rate of slow responding fibers, thus reducing conduction velocity and prolonging ERP.
2.Clinically used antiarrhythmic drugs
2.1 Class I antiarrhythmic drugs
Quinidine
[Clinical pharmacology] It has the cellular electrophysiological effect of class IA drugs. Quickly absorbed orally, bioavailability is about 70% (44-98%). 90% is metabolized by liver, 10-13% of the original form is excreted in urine. Single dose of his t1/2 4-6 hours. Steady state in arrhythmia is t1/2 4.5 hours. HPLC effective blood concentration 0.7-5ug/ml, toxic concentration 5ug/ml.
[Indications] Supraventricular tachycardia (supraventricular tachycardia), premature atrial or nodal beats, atrial fibrillation (atrial fibrillation), atrial flutter (atrial flutter); pre-excitation syndrome (pre-excitation) combined with supraventricular arrhythmias; premature ventricular beats (premature ventricular), ventricular tachycardia (ventricular tachycardia) and ventricular fibrillation (ventricular fibrillation).
[Contraindications] Hypersensitivity to quinine or this product: pregnant women and lactating mothers; digitalis toxicity; cardiogenic shock; severe hepatic or renal impairment; abnormal pacing or conduction function; hypokalemia should be considered as contraindications.
[Adverse reactions] Cardiac block and aggravated heart failure, polymorphic ventricular tachycardia or ventricular fibrillation; diarrhea, nausea, vomiting, dizziness and tinnitus; hypotension, convulsions, psychiatric disorders, respiratory depression, rash, fever and decreased hemolytic anemia.
[Usage] When reversing paroxysmal supraventricular tachycardia, atrial fibrillation and atrial flutter, try 0.2g on the 1st day before administration to observe allergic and idiosyncratic reactions. On day 1, 0.2g every 2 hours for 5 consecutive doses; if ineffective and no adverse reactions, increase to 0.3g each time on day 2; on day 3, 0.4g every 2 hours for 5 consecutive doses. The total daily amount should not exceed 2.5g. After restoration of sinus rhythm, the maintenance amount should be changed to 0.2g, 3-4 times a day. The maintenance dose of extended-release tablets is 300-325mg once in 8-12 hours.
Procainamide (procainamide)
[Clinical Pharmacology] It has the cellular electrophysiological effect of class IA drugs, with fast and complete oral absorption, the absorption rate can reach 75-95%, mainly metabolized in the liver. Therapeutic plasma concentration range is 4-20ug/ml, 4-10ug/ml.
[Indications] Maintenance therapy for premature ventricle, ventricular tachycardia, paroxysmal supraventricular tachycardia, preexcited combined supraventricular arrhythmias and atrial fibrillation or atrial flutter after electrical diversion.
[Contraindications] Hypersensitivity to this drug or procaine; history of lupus erythematosus or disease; pacing or conduction dysfunction; seedy muscle weakness; severe hypotension; hepatic or renal dysfunction.
[ADVERSE REACTIONS] Cardiac arrest and conduction block may occur with this drug; ventricular arrhythmias including polymorphic (torsional) ventricular tachycardia or ventricular fibrillation, and hypotension due to vasodilation by intravenous injection. Gastrointestinal reactions. Lupus erythematosus-like syndrome.
[Usage] For supraventricular or ventricular arrhythmias take 0.5-0.75g every 4 hours, the total daily amount should not exceed 3.0g; intravenous medication is first administered as 100mg for 5 minutes and reintroduced every 5-10 minutes if necessary, the total amount should not exceed 10-15mg/kg, or as 10-15mg/kg for 1 hour followed by 1.5-2.0mg/kg/h Maintenance. Blood pressure and electrocardiogram should be closely monitored for intravenous administration.
Disopyramide
[Clinical Pharmacology] It has the electrophysiological effect of IA class drug cells. Bioavailability in healthy subjects is about 70-80%. About 25% is metabolized by the liver, about 50% is excreted in the urine, and 30% is excreted by the bile duct. Delayed clearance in renal dysfunction may cause accumulation of the original drug, and the blood concentration of long-term drug users is independent of the dose.
[Indications] Ventricular premature and paroxysmal ventricular tachycardia, pre-excitation with atrial fibrillation, atrial flutter or supraventricular tachycardia; maintenance of rhythm after atrial premature or electrical cardioversion. Intravenous administration is indicated for ventricular tachycardia or supraventricular tachycardia for which lidocaine or electrotransfer therapy is ineffective or inappropriate.
[Contraindications] It is contraindicated in cases of hypersensitivity to this drug: atrioventricular block of degree I or higher; sick sinus syndrome; cardiogenic shock; glaucoma and urinary retention.
[Adverse reactions] May cause heart block and arrest. Exacerbate ventricular arrhythmias including polymorphic ventricular tachycardia and ventricular fibrillation, producing hypotension and heart failure. Dry mouth, nausea, anorexia, constipation and urinary retention, abnormal liver function or hepatic cholestasis, granulocytopenia, eye loss, psychiatric abnormalities, aggravated glaucoma, etc., hypoglycemia, impotence and skin rash.
[Usage] Adults take 200mg for the first time, then 100-200mg once in 6 hours.
2mg/kg for more than 5 minutes, the amount should not exceed 150mg each time, and can be repeated once after 20 minutes, or followed by 0.4mg/(kg-h) for static maintenance, the total amount should not exceed 800mg per day.
Lidocaine
[Clinical Pharmacology] It has the electrophysiological effect of class IB drug cells. It is well absorbed orally, but the hepatic first-pass effect is up to 70%, mainly metabolized by the liver, and the rate of metabolism is related to hepatic blood flow. Therapeutic plasma concentration is 2-5ug/m, more than l5ug/ml some people can produce toxicity, more than 10ug/ml can cause serious poisoning.
[Indications] For ventricular arrhythmias caused by AMI, cardiac surgery, cardiac catheterization, digitalis toxicity, etc.
[Contraindications] Use with caution in second or third degree AV block, double branch conduction block, severe sinus node dysfunction and severe hepatic dysfunction.
[Adverse effects] Dizziness, lethargy, slurred speech, abnormal sensation, muscle tremors, even convulsions, confusion and respiratory depression. High doses may cause severe sinus bradycardia, conduction block and decreased myocardial contractility. Allergic reactions may result in rash, edema and respiratory arrest.
[Usage] The first intravenous injection of 50-100mg for 2-3 minutes, re-injected every 5 minutes if necessary, should not exceed 300mg in 1 hour, followed by intravenous drip of 1-4mg/min to maintain.
Children should be given 0.5-1mg/kg intravenously for the first time for 2-3 minutes, and if necessary, it can be repeated once, the total amount should not exceed 3mg/kg, followed by 0.015-0.03mg/kg for maintenance by IV drip. The dose should be reduced in the elderly and those with poor hepatic function, severe heart failure or shock.
Tocainide
[Clinical Pharmacology] Has class IB cell electrophysiological effects. It can be administered orally or intravenously, and its bioavailability is over 90% after administration. 60% of the drug is metabolized by the liver, 40% is excreted by the kidney in its original form, and the general effective concentration is 4-10ug/ml. sodium bicarbonate can increase the urinary PH and reduce the clearance of the drug. beta-blockers can increase the inhibitory effect on hemodynamics and conduction.
[Therapeutic application] Oral administration is suitable for ventricular arrhythmias. Intravenous injection is suitable for acute ventricular arrhythmias and may occasionally be effective in atrioventricular bypass arrhythmias.
[Contraindications] Bifurcation, second or third degree AV block is contraindicated. Use with caution in uncorrected heart failure.
[ADVERSE REACTIONS] Tremor, vertigo, headache, dizziness, unsteady gait, memory loss, unresponsiveness, inattention, abnormal sensations and convulsions, altered vision and tinnitus. Gastrointestinal reactions. Skin rash, fine lupus, neck muscle spasms, sweating and flushing. Aggravated heart failure or conduction disturbances. Rarely, interstitial pneumonia may occur.
[Usage] Treatment of ventricular arrhythmia can be slow intravenous 500-750mg; or 50-100ml of glucose or saline diluted in 15-30 minutes IV, followed by oral 600-800mg, then 1.2g/d in 2-3 maintenance doses, can be increased to 1.8-2.4g/d if necessary.
Mexiletinum
[Clinical Pharmacology] It has the electrophysiological effect of class IB drug cells. Oral absorption from the intestine is rapid and complete. Oral bioavailability is about 90%. The time to peak blood concentration is 1.5-4 hours. Therapeutic plasma concentration is 0.75-2ug/ml. the drug is mainly metabolized by the liver, metabolites may be inactive.
[Therapeutic Applications] Oral administration is indicated for chronic ventricular arrhythmias, including premature ventricular and ventricular tachycardia. Intravenous injection is suitable for acute ventricular arrhythmias.
[Pharmacologic effects] Severe sinus node dysfunction: atrioventricular block of degree II or III and double branch block; severe hepatic dysfunction should be contraindicated.
[Adverse reactions] Higher incidence of intravenous administration, sinus bradycardia or sinus arrest, intraventricular block, aggravated ventricular arrhythmias, hypotension and heart failure. Gastrointestinal reactions Neurological symptoms include dizziness, tremor, diplopia, coma and convulsions.
[Usage] Adult maintenance dose is about 600-900mg/d divided into 3-4 doses. The first 100-200mg (diluted with 5% glucose 20ml) is injected intravenously within 10-15 minutes, then maintained at 0.5-1.5mg/min, and reduced to 0.75-1mg/min after 3-4 hours, maintained for 24-48 hours.
Ethmozine
[Clinical Pharmacology] It has the electrophysiological effect of class IB drug cells. It is readily absorbed orally, with a bioavailability of 45±30%. It is metabolized by the liver and excreted by the kidney. The effective blood concentration is 147.5±11.1ug/nl.
[Indications] Mainly suitable for ventricular arrhythmias, poorly effective for supraventricular arrhythmias.
[Contraindications] Cardiac block and sinus node insufficiency should be prohibited. Use with caution in patients with severe cardiac insufficiency and hepatic and renal dysfunction.
[CAST effects: nausea, loss of appetite, dizziness, headache, tremor, numbness, euphoria, visual disturbances and rash.
[Usage] 150-300mg every 6 hours, or 6-15mg/kg daily in 3-4 oral doses. Less than 600mg/d has poor efficacy.
Phenytoinum natrium
[Clinical Pharmacology] Has an electrophysiological effect on the cells of class IB drugs. Gastrointestinal absorption is slow but complete, 95% is metabolized by the liver, and its metabolites are not pharmacologically active. The effective plasma concentration is about 10-20ug/ml, and the effect does not increase when it exceeds 20ug/ml.
[Therapeutic application] It is mainly suitable for ventricular and supraventricular arrhythmias due to digitalis toxicity, ventricular arrhythmias due to other causes (electrotransfer, postoperative cardiac surgery, catheterization and anesthetics, etc.) that are ineffective or unavailable for lidocaine.
[Contraindications] Hematologic disorders; second or third degree AV block (except second or third degree AV block due to digitalis toxicity); sick sinus syndrome; hypotension; severe cardiac or hepatic insufficiency should be contraindicated.
[Adverse reactions] Short-term intravenous use is mainly cardiovascular and central nervous system adverse reactions.
[Drug Interactions]
(1) Alcohol and barbiturates increase clearance and therefore decrease plasma concentration;
(2) Folic acid decreases its use;
(3) This drug increases the blood concentration of promethazine and amitriptyline;
(4) Combined use with antipsychotics and tricyclic anti-inhibitors can cause seizures.
(5) This drug can increase the metabolism of calcifediol.
[Usage] Adults take 100-300mg orally once or 10-15mg/kg in 2-3 doses, 7.5-10mg/kg on day 2-4, then 2-6mg/kg daily for maintenance. 100mg once for 2-3 minutes, then repeat every 10-15 minutes as needed until arrhythmia is aborted or adverse effects occur, but the total amount should not exceed 500mg.
Propafenone (also known as propafenone)
[Clinical pharmacology has IC-like drug cell electrophysiological effect. It is well absorbed orally, but the first-pass effect is obvious. The physiological utilization is about 4.8-23.5%, and the patient takes about 3.6+0.2 hours for a single dose, and 6-7 hours on average for multiple doses. The effective blood concentration varies greatly among individuals, with a mean of about 588-800ng/ml.
[Indications] Oral administration is mainly indicated for ventricular arrhythmias, followed by supraventricular arrhythmias, but intravenous injection is indicated for aborting paroxysmal ventricular tachycardia and supraventricular tachycardia.
[Contraindications] Severe sinus node dysfunction; II or III degree AV block; double branch block, cardiogenic shock are contraindicated. Intraventricular block in heart failure with QRS > 0.12s.
[ADVERSE REACTIONS] May cause sinus arrest or conduction block; aggravation of ventricular arrhythmias, hypotension and heart failure; dizziness, convulsions, disorientation, weakness; mild nausea, constipation, dry mouth; elevated hepatic transenzymes and cholestatic hepatitis.
(1) Warfarin competes with its plasma protein binding site, which may increase the free drug concentration and enhance its effect and toxicity. (2) Combined use with other antiarrhythmic drugs may aggravate cardiac adverse effects. (3) Combination with antihypertensive drugs may enhance the antihypertensive effect. (4) May increase serum digoxin concentration.
[Usage] 450-900mg/d orally, a small amount of 1200mg is required, divided into 1 dose in 6-8 hours. Children 5-7mg/kg/day. 1-1.5mg/kg intravenously over 5 minutes, repeated after 20 minutes if necessary, followed by 0.5-1mg/min maintenance. Children 1mg/kg intravenously.
Flucarbamide (also known as flecainide)
[Clinical Pharmacology] It has the electrophysiological effect of IC-like drug cells. Oral absorption is rapid and complete up to 90% in healthy people. The original drug is metabolized by the liver, and the plasma concentration reaches its peak in 4 hours after taking.
[Indications] It is suitable for supraventricular arrhythmias and can prevent paroxysmal atrial fibrillation attacks. It is mainly suitable for the arrest and prevention of ventricular arrhythmias, including premature ventricular and ventricular tachycardia.
[Contraindications] Contraindicated in extremely poor cardiac function and in atrioventricular block of degree II or III. Caution should be exercised in patients with bundle branch or intraventricular conduction block and cardiac or renal dysfunction.
[Adverse reactions] Atrioventricular, bundle-branch and intraventricular block may occur or be aggravated. It may also induce or aggravate ventricular arrhythmias and heart failure. Secondary effects include dizziness, headache, visual disturbances, impotence, nausea and elevated serum alkaline phosphatase.
[Usage] Intravenous 1-2mg/kg min. Oral administration of 200-600mg/d in 3 doses may alleviate visual disturbances due to peak blood levels of both doses.
Encainide
[Clinical Pharmacology] It has the electrophysiological effect of IC-like drug cells. It is fast and completely absorbed after oral administration, with an average bioavailability of 42-24%, and is metabolized by the liver.
[Indications] It is suitable for the treatment of ventricular arrhythmias, especially for users for whom conventional antiarrhythmic drugs are ineffective or inappropriate. Oral administration may be effective in some cases of supraventricular arrhythmias.
[Contraindications] Second or third degree atrioventricular block, double branch block; severe cardiac or renal insufficiency should be contraindicated. It should be used with caution in patients with sick sinus syndrome or bundle branch block.
[Adverse Reactions] May aggravate arrhythmias, produce or aggravate conduction block and aggravate heart failure. It may also cause dizziness, headache, tremor, speech disturbance, visual disturbance, fatigue, nausea, diarrhea and rash.
[Usage] Oral 25-50mg per dose, 3-4 times a day, may be increased by 12.5mg every 3-5 days, total amount should not exceed 300mg/d. 1mg/kg can be used intravenously for 20 minutes, single dose should not exceed 75mg. 25mg can also be injected intravenously for the first time, then gradually increased, total amount should not exceed 300mg/d.
Lorcainide
[Clinical Pharmacology] It has the electrophysiological effect of IC-like drug cells. It is completely absorbed after administration, and the bioavailability is 24.5% after a single dose. It is mainly metabolized by the liver into cardiac active metabolites.
[Indications] It is suitable for acute ventricular arrhythmias and can stop ventricular tachycardia, ventricular fibrillation and frequent ventricular premature. Oral administration is suitable for chronic ventricular arrhythmias and some supraventricular arrhythmias, but is less effective in atrial fibrillation and atrial flutter.
[Contraindications] It is contraindicated in patients with branch block or intraventricular block and atrioventricular block of degree II or III. It should be used with caution in patients with sick sinus syndrome.
[ADVERSE REACTIONS] Atrioventricular block, muscle tremor, blurred vision, vertigo and abnormal sensation may occur with high sedation doses. Oral administration may cause nausea, insomnia, and excessive dreaming, which can be treated with Valium.
[Usage] Start with 25-50mg intravenous injection for 5 minutes, repeat once after 25 minutes, total amount not more than 200mg, followed by 1.5-2mg/min intravenous drip. Or 20mg/min IV drip for 10 minutes, followed by 1.5-2mg/min IV drip. 50-20mg orally, 2-3 times daily.
2.2 ß-blockers
Metoprolol
[Clinical Pharmacology] It is rapidly and completely absorbed orally (>95%), and its bioavailability is about 50%; T1/2 is 3~5 hours; it is metabolized in the liver and excreted by the kidney; only a small amount (3%~10%) is in its original form.
[Indications] It can be used for the treatment of supraventricular tachyarrhythmias, ventricular arrhythmias, tachyarrhythmias caused by digitalis and catecholamines, and is more effective in tachyarrhythmias caused by hypertension, coronary artery disease and increased catecholamines. It can antagonize the effect of catecholamines and can treat arrhythmias caused by hyperthyroidism.
[Contraindications]
Second or third degree AV block, decompensated heart failure (pulmonary edema, hypoperfusion or hypotension); clinically significant sinus bradycardia, pathological sinus node syndrome, cardiogenic shock; poor perfusion of the peripheral circulation, severe peripheral vascular disease.
[Adverse effects] Cardiovascular system: slowed heart rate, conduction block, decreased blood pressure, increased heart failure, cold extremities or inability to palpate a pulse due to peripheral vasospasm, Raynaud’s disease. Fatigue and vertigo accounted for 10% and depression for 5%. Digestive system (nausea, stomach pain). Cardiovascular system: slowed heart rate, conduction block, decreased blood pressure, increased heart failure, cold extremities or inability to palpate a pulse due to peripheral vasospasm, Raynaud’s disease. Fatigue and bloating dizziness accounted for 10% and depression for 5%. Digestive system.
[Usage] Oral. 12.5-25mg Bid, may increase dose 50mg/Bid
Intravenous application of betalactam should be done under the supervision of an experienced physician. Also, the patient’s blood pressure and ECG should be carefully monitored and resuscitation resuscitation facilities should be available. Supraventricular tachyarrhythmias: Start with intravenous administration at 1-2 mg/min in a dosage of up to 5 mg (5 ml); if the condition requires, repeat injections at 5-minute intervals for a total dose of 10-15 mg (4-6 hours after intravenous injection, when the arrhythmia has been controlled, maintain with oral preparations, 2-3 times a day, with each dose not exceeding 50 mg).
Atenolol (atenolol)
[Clinical Pharmacology] Absorbed orally quickly, the absorption rate is only 46~62%, and the excretion of the original drug in the urine is about 85~100 %.
[Indications] For the treatment of supraventricular tachyarrhythmias, digitalis and catecholamine-induced tachyarrhythmias. It can antagonize the effect of catecholamines and can treat arrhythmias caused by hyperthyroidism.
[Contraindications] Grade II or III AV block, decompensated heart failure (pulmonary edema, hypoperfusion or hypotension); clinically significant sinus bradycardia, pathological sinus node syndrome, cardiogenic shock; poor perfusion of peripheral circulation, severe peripheral vascular disease.
[ADVERSE REACTIONS] Induced and aggravated heart failure; sinus bradycardia, atrioventricular block; rash, arthralgia; bronchospasm.
[Usage] Oral dose 25~100mg/d, once daily or in 2 divided doses.
Propranolol (also known as propranolol)
[Clinical Pharmacology] Oral absorption rate of 90% on, widely metabolized in the liver.
[Indications] It has been used less frequently in anti-arrhythmia. It can be used for the control of sinus tachycardia, atrial tachycardia, atrial fibrillation, and atrial flutter ventricular rate.
[Contraindications] It is not recommended for patients with asthma. Not recommended or used with caution in patients with atrioventricular block, obstructive pulmonary disease, congestive heart or diabetes mellitus.
[Adverse effects] Dizziness, fatigue, insomnia, nausea, vomiting, muscle pain and asthma may occur at the beginning of treatment. Long-term use of the drug may cause severe bradycardia and induce acute heart failure.
[Usage] The starting dose should be small, 10~20mg each time, 3~4 times a day.
Esmolol Hydrochloride
[Clinical Pharmacology] It is an ultra-short-acting, highly selective ß1 receptor blocker, which slows down heart rate, lowers systolic blood pressure and reduces myocardial oxygen consumption, with rapid onset and short duration of action; the ß1 receptor blocking effect is completely eliminated after 20 minutes upon termination of titration, and the hemodynamic effect returns to baseline level after 30 minutes.
[Indications]
Indicated for the development of tachycardia and sinus tachycardia, atrial flutter, antifibrillation control of ventricular rate in the perioperative period (induction of anesthesia, during anesthesia or after surgery).
[Contraindications] Bronchial asthma or history of bronchial asthma, severe chronic obstructive pulmonary disease; sinus bradycardia, second to third degree atrioventricular block. Refractory cardiac insufficiency, cardiogenic shock. Hypersensitivity to this product
[Adverse reactions] Occasionally hypotension, bradycardia, mostly occurring after 5 minutes of use should.
[Dosage] For the treatment of tachyarrhythmias, a loading dose of 0.5mg/kg can be used as a maintenance dose of 0.25-0.5mg/kg.min.
2.3 Class III antiarrhythmic drugs
Amiodarone (amiodaronum)
[Clinical Pharmacology] This product is a class III antiarrhythmic drug. Oral absorption is slow, bioavailability is about 31-65%, mainly metabolized by liver, t1/2 is 19±9 days after long-term dosing.
[Indications] It is suitable for the treatment and prevention of various tachyarrhythmic episodes by oral administration, especially those combined with pre-excitation. Intravenous injection can be used to abort paroxysmal supraventricular tachycardia, especially in combination with pre-excitation. It can reduce the ventricular rate in rapid atrial fibrillation or atrial flutter. It can be used for ventricular arrhythmias that are not treated with lidocaine.
[Contraindications] Contraindicated in patients with a history of abnormal thyroid function or existing abnormal function; iodine hypersensitivity; atrioventricular communicating ventricular block of degree I, III; double branch block; Q-T prolongation syndrome; sinus syndrome. Caution should be exercised when administering for severe cardiac insufficiency, hypotension or shock. Caution should also be exercised when administered orally to patients with hepatic or pulmonary insufficiency.
[Adverse reactions] may cause severe sinus bradycardia, sinus arrest or sinus block, atrioventricular block, polymorphic ventricular tachycardia with QT prolongation; injection may cause hypotension. May cause hyperthyroidism or hypothyroidism. Nausea, vomiting, constipation. Subcorneal hyperpigmentation, affecting vision, peripheral neuropathy. It may cause interstitial or alveolar fibrous pneumonia with clinical shortness of breath, dry cough, chest pain, rapid hematocrit, hematocrit, and in severe cases, death. Occasionally, it has been reported to cause hypocalcemia and elevated serum creatinine. Intravenous injection is prone to phlebitis, so it is advisable to use larger veins. It can increase the blood concentration of digoxin, hyperamphetamine, quinidine, procainamide and N-acetyl procainamide, and aggravate the adverse effects.
[Usage] For supraventricular arrhythmias, 400-600mg/d can be taken in 2-3 divided doses, and then changed to 200-400mg/d for maintenance after 1-2 weeks. For ventricular arrhythmias, 800-1200mg can be taken in 3 divided doses, and then changed to 200-600mg/d for maintenance after 1-2 weeks. For intravenous injection, 5mg-kg can be injected slowly for 10-15 minutes, and can be repeated once after 15-30 minutes. Blood pressure, heart rate and heart rhythm should be measured during intravenous administration.
Sotalol Hydrochlorde
[Clinical Pharmacology] This product has the properties of both II (blocking ß receptors) and III (prolonging the duration of myocardial action potential) antiarrhythmic drugs. The oral bioavailability of sotalol hydrochloride is basically complete (more than 90%), peak concentration is reached 2.5+0.98 hours after oral administration, steady-state blood concentration is reached in 2~3 days, half-life is 10~20 hours, the main route of elimination is renal excretion, about 80~90% is excreted by urine as prototype, the rest is excreted by feces.
[Indications] For various life-threatening ventricular tachyarrhythmias.
[Adverse effects] Cardiovascular: bradycardia, dyspnea, chest pain, palpitations, edema, ECG abnormalities, hypotension, arrhythmogenic, syncope, heart failure. Cutaneous: nausea, vomiting, diarrhea, dyspepsia, abdominal pain, gastrointestinal distention. Muscle: spasm. Nervous, mental: fatigue, dizziness, weakness, headache, sleep disorders, depression, abnormal sensations, mood changes, anxiety. Reproductive system: sexual dysfunction. The incidence of arrhythmogenic adverse reactions is 4.3%
[Contraindications]
Contraindicated in bronchial asthma, sinus bradycardia, second or third degree AV block (unless an effective pacemaker is placed), congenital or acquired QT interval prolongation syndrome, cardiogenic shock, uncontrolled congestive heart failure, and in patients with hypersensitivity to this product.
[Dosage].
80-120 mg/dose orally, 2-3 times daily, dose may be increased to 0.24-0.32 g/day.
2.4 Class IV antiarrhythmic drugs
Verapamil (also known as isoptin verapamil)
[Clinical Pharmacology] It is a class IV antiarrhythmic drug. It is absorbed orally up to 90%, but the first-pass effect is obvious, and the bioavailability is only 10-20%, mainly metabolized by the liver.
[Indications] It is indicated for the abortion of folded supraventricular tachycardia and normal graphic preexcitation combined with episodes of supraventricular tachycardia. May reduce ventricular rate in atrial fibrillation or atrial flutter. Poor effect on ventricular arrhythmias, but sensitive to left ventricular idiopathic ventricular tachycardia.
[Contraindications] Sick sinus syndrome; atrioventricular block of degree II or III; severe heart failure or hypotension should be contraindicated.
[Adverse reactions] Intravenous injection may cause hypotension; occasionally sinus bradycardia or bradyarrhythmias, atrioventricular block of degree II or greater.
[DOSAGE] The first dose of 5mg or 0.075mg/kg can be given intravenously for 2-3 minutes, followed by 0,005mg-kg/(kg-min) IV or repeat 5mg after 30 minutes, and 40-80mg orally once every 8 hours. Total dose should not exceed 720mg/d.
Thiodiazepine (Diltiazem)
[Clinical Pharmacology] It belongs to class IV antiarrhythmic drugs. The oral absorption rate is >40%, but the bioavailability is only about 40% due to the first-pass metabolism effect in the liver. After intravenous injection, the drug rapidly appears in the bile and gastrointestinal tract. 96-99% of the drug is metabolized in the body in T1/24-6 hours, and 60% of the metabolites are excreted in the feces and 40% are eliminated in the urine.
[Indications] Intravenous drip can treat supraventricular tachycardia; control the ventricular rate of atrial fibrillation and atrial flutter; treat premature atrial contractions.
[Contraindications] Contraindicated in atrioventricular block, pathological sinus node syndrome, hypotension and pregnant women. Use with caution in patients with significant cardiac decompensation and in lactating women.
[ADVERSE REACTIONS] Dizziness, headache, flushing, insomnia; gastrointestinal symptoms; atrioventricular block; hypotension; occasional liver damage; sinus bradycardia, sinus arrest, severe atrioventricular block may occur when administered intravenously.
[Usage] Take 15-30mg orally 3-4 times daily. For intravenous injection, the first dosage is 0.25mg/kg diluted and slowly injected intravenously. Maintenance dose 5-15mg/hour, IV.
2.5 Other antiarrhythmic drugs
Adenosine triphosphate
[Clinical pharmacology] Inhibits slow channels, activates potassium channels, shortens sinus node and atrioventricular node action potential time course, increases membrane potential; inhibits sinus node autoregulation, slows down atrioventricular node conduction. Rapid intravenous administration, T1/21-6s, rapid degradation after entering tissues, complete loss of action after 2min.
[Indications] Termination of AV nodal refractory and AV refractory tachycardia; temporary slowing of ventricular rate in patients with atrial tachycardia, atrial flutter or atrial fibrillation. Used for differential diagnosis of tachycardia during electrophysiological examination. Not effective for bypass conduction and ventricular tachycardia.
[Contraindications] Use with caution in the elderly or in coronary artery disease, and contraindicated with a history of allergy. Contraindicated in sinus bradycardia, sinus arrest and conduction block.
[Adverse reactions] Flushing, dyspnea, chest pressure, dizziness, headache, head swelling, nausea, vomiting, etc.; hypotension; transient slow arrhythmias.
[Interaction] Antagonistic effect with methylxanthine coffee and theophylline, enhanced effect with pansentine, increased AV node conduction block with carbamazepine.
[Usage] 10-20mg intravenously without dilution, single dose does not exceed 30mg.
Adenosine
Pharmacological effects, indications, contraindications and adverse reactions are similar to those of adenosine triphosphate, with the following major.
[Pharmacokinetics] Intravenous adenosine is rapidly transferred to erythrocytes and endothelial cells with an elimination half-life of 1.5 to 10 s. The drug is rapidly metabolized in the plasma and forms inosine and adenosine monophosphate in the cells. The maximum pharmacological effect is seen 30 seconds after sedation.
[Drug Interaction] Pansentin blocks cellular uptake of adenosine and increases adenosine potency, while caffeine and tea minus decrease adenosine potency.
[Usage] The starting dose for adults is to push in 6mg/1~2 seconds, if the tachycardia is not terminated, 12mg will be given after 1-2 minutes interval and can be repeated.
3.Drug treatment of various arrhythmias
Attention should be paid to all kinds of arrhythmias to seek whether there are other factors causing the arrhythmia and to treat them. Such as.
(1) electrolyte disorders, especially low blood potassium is most common. Magnesium deficiency should also be noted.
(2) Arrhythmias caused by the use of drugs, such as digitalis preparations. Many anti-arrhythmic drugs also have adverse reactions that produce arrhythmias.
(3) Suffering from certain diseases such as hyperthyroidism, acid-base imbalance, etc.. Excessive smoking and alcohol may also trigger arrhythmias.
3.1 Atrial premature beats
If there is no organic heart disease and the cause is removed, treatment is usually not needed.
Long-term antiarrhythmic drug therapy is not recommended for those with ischemia and heart failure.
For atrial premature beats with induced supraventricular tachycardia and atrial fibrillation, pharmacological treatment is an option.
Drug therapy: β-blocker atenolol 6.25-25mg, bid. betalactam 12.5-25mg bid. calcium antagonists: verapamil 40-120mg bid; heximide 15-30mg q6h. class I antiarrhythmic drugs: propafenone 100-200mg q6h.
3.2 Atrial tachycardia
The aim of treatment is to terminate the attack or control the ventricular rate, β-blockers can be chosen; propafenone 150-200mg q6h; verapamil 40-120mg bid; thioridone 15-30mg q6h; amiodarone. For those who need long-term treatment, in addition to the above drugs, amiodarone is preferred for patients with heart failure, and for those with normal heart function, class Ia or Ic drugs can be chosen.
3.3 Treatment of atrial fibrillation and atrial flutter
Treatment in episodes of atrial fibrillation in Chenopenia: including diversion and control of ventricular rate
Propafenone 70mg + 5% glucose 20ml intravenously;
Intravenous cetiran 0.4-0.8mg, or intravenous calcium antagonist or beta-blocker, which aims to reduce the ventricular rhythm to below 100 beats/min.
Intravenous amiodarone (same dose as for supraventricular tachycardia) has a high effect of terminating the attack in patients who have had an episode for a short time.
Maintenance of sinus rhythm: amiodarone, sotalol; propafenone, ethamethoxazole; quinidine.
Control of ventricular rate: beta-blockers; calcium antagonists.
Prevention of thrombosis: aspirin; warfarin to maintain INR at 1.8-2.5.
3.4 Treatment during episodes of obsolete supraventricular tachycardia (supraventricular tachycardia)
(1) Propafenone 70 mg + 5% glucose 20 ml slowly intravenously.
(2) Verapamil 5mg in 5% glucose solution as a slow intravenous injection, which can be repeated within 10 minutes after injection.
(3) Adenosine 6-12mg intravenous push.
(4) Ethylene iodofurazone 300mg (or 5mg/kg body weight) in 5% grape solution 100ml intravenously, finished within 30 minutes.
3.5 Treatment of premature ventricular contractions
Ventricular premature contractions that require treatment are treated according to their occurrence
(1) For ventricular premature beats in acute myocardial infarction, start with 50-100 mg intravenous attention, then drip intravenously at a rate of 1-3 mg/min. Mexilate: first 100-20mg equilibrium release followed by intravenous tautly slow injection then continuous intravenous drip at a rate of 1-4mg/min.
Mecillin: start with 100-200mg 3 times a day, and then gradually reduce the maintenance after effective.
(2) Amiodarone therapy is preferred for organic heart disease with hypocardium.
(3) Those without organic heart disease can choose; beta-blocker; mexiletine; propafenone; amiodarone, etc.
3.6 Prevention and treatment of ventricular tachycardia (ventricular tachycardia) and ventricular fibrillation (ventricular fibrillation)
(1) Idiopathic ventricular tachycardia originating in the right ventricle: propafenone; verapamil; beta-blockers; adenosine; lidocaine. Idiopathic ventricular tachycardia originating from the left ventricle: verapamil is preferred.
(2) In ventricular tachycardia with organic heart disease, the drug of choice is currently etanercept, which starts at 1.0-1.2 g daily and is switched to a maintenance dose of 0.3-0.4 g/d after 7-10 days of continuous use. propafenone, procainamide, sotalol or beta-blockers are used for normal cardiac function.
3.7 Treatment of “torsional ventricular tachycardia”
(1) Discontinue digitalis and class I and III antiarrhythmic drugs.
(2) Give isoproterenol 0.1 mg in 100 ml of liquid and administer it intravenously at a rate of 0.5-1.0ug/min.
(3) Intravenous potassium supplementation.
If the attack is prolonged, electrical diversion should be performed.