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Pharmacology of Antiarrhytmic Drug

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Presentation on theme: "Pharmacology of Antiarrhytmic Drug"— Presentation transcript:

1 Pharmacology of Antiarrhytmic Drug
M. Saifur Rohman, dr. SpJP. PhD. FICA Department of Cardiology and Vascular Medicine Faculty of Medicine, Brawijaya University

2 Mechanism of Arrhythmia
Abnormal heart pulse formation Sinus pulse Ectopic pulse Triggered activity Abnormal heart pulse conduction Reentry Conduct block

3 Classification of Arrhythmia
Abnormal heart pulse formation Sinus arrhythmia Atrial arrhythmia Atrioventricular junctional arrhythmia Ventricular arrhythmia Abnormal heart pulse conduction Sinus-atrial block Intra-atrial block Atrio-ventricular block Intra-ventricular block Abnormal heart pulse formation and conduction

4 Anti-tachycardia agents
Modified Vaugham Williams classification I class: Natrium channel blocker II class: ß-receptor blocker III class: Potassium channel blocker IV class: Calcium channel blocker Others: Adenosine, Digital

5 Classification of antiarrhythmics (based on mechanisms of action)
Class I – blocker’s of fast Na+ channels Subclass IA Cause moderate Phase 0 depression Prolong repolarization Increased duration of action potential Includes Quinidine – 1st antiarrhythmic used, treat both atrial and ventricular arrhythmias, increases refractory period Procainamide - increases refractory period but side effects Disopyramide – extended duration of action, used only for treating ventricular arrthymias

6 Classification of antiarrhythmics (based on mechanisms of action)
Subclass IB Weak Phase 0 depression Shortened depolarization Decreased action potential duration Includes Lidocane (also acts as local anesthetic) – blocks Na+ channels mostly in ventricular cells, also good for digitalis-associated arrhythmias Mexiletine - oral lidocaine derivative, similar activity Phenytoin – anticonvulsant that also works as antiarrhythmic similar to lidocane

7 Classification of antiarrhythmics (based on mechanisms of action)
Subclass IC Strong Phase 0 depression No effect of depolarization No effect on action potential duration Includes Flecainide (initially developed as a local anesthetic) Slows conduction in all parts of heart, Also inhibits abnormal automaticity Propafenone Also slows conduction Weak β – blocker Also some Ca2+ channel blockade

8 Classification of antiarrhythmics (based on mechanisms of action)
Class II – β–adrenergic blockers Based on two major actions 1) blockade of myocardial β–adrenergic receptors 2) Direct membrane-stabilizing effects related to Na+ channel blockade Includes Propranolol causes both myocardial β–adrenergic blockade and membrane-stabilizing effects Slows SA node and ectopic pacemaking Can block arrhythmias induced by exercise or apprehension Other β–adrenergic blockers have similar therapeutic effect Metoprolol Nadolol Atenolol Acebutolol Pindolol Stalol Timolol Esmolol

9 Classification of antiarrhythmics (based on mechanisms of action)
Class III – K+ channel blockers Developed because some patients negatively sensitive to Na channel blockers (they died!) Cause delay in repolarization and prolonged refractory period Includes Amiodarone – prolongs action potential by delaying K+ efflux but many other effects characteristic of other classes Ibutilide – slows inward movement of Na+ in addition to delaying K + influx. Bretylium – first developed to treat hypertension but found to also suppress ventricular fibrillation associated with myocardial infarction Dofetilide - prolongs action potential by delaying K+ efflux with no other effects

10 Classification of antiarrhythmics (based on mechanisms of action)
Class IV – Ca2+ channel blockers slow rate of AV-conduction in patients with atrial fibrillation Includes Verapamil – blocks Na+ channels in addition to Ca2+; also slows SA node in tachycardia Diltiazem

11 Anti-bradycardia agents
ß-adrenic receptor activator M-cholinergic receptor blocker Non-specific activator

12 Clinical usage Anti-tachycardia agents: Ia class: Less use in clinic
Guinidine Procainamide Disopyramide: Side effect: like M-cholinergic receptor blocker

13 Anti-tachycardia agents:
Ib class: Perfect to ventricular tachyarrhythmia 1. Lidocaine 2. Mexiletine

14 Anti-tachycardia agents:
Ic class: Can be used in ventricular and/or supra-ventricular tachycardia and extrasystole. 1. Moricizine 2. Propafenone

15 Anti-tachycardia agents:
II class: ß-receptor blocker Propranolol: Non-selective Metoprolol: Selective ß1-receptor blocker, Perfect to hypertension and coronary artery disease patients associated with tachyarrhythmia.

16 Anti-tachycardia agents:
III class: Potassium channel blocker, extend-spectrum anti-arrhythmia agent. Amiodarone: Perfect to coronary artery disease and heart failure patients Sotalol: Has ß-blocker effect Bretylium

17 Anti-tachycardia agents:
IV class: be used in supraventricular tachycardia Verapamil Diltiazem Others: Adenosine: be used in supraventricular tachycardia

18 Anti-bradycardia agents
Isoprenaline Epinephrine Atropine Aminophylline

19 Proarrhythmia effect of antiarrhythmia agents
Ia, Ic class: Prolong QT interval, will cause VT or VF in coronary artery disease and heart failure patients III class: Like Ia, Ic class agents II, IV class: Bradycardia

20 Non-drug therapy Cardioversion: For tachycardia especially hemodynamic unstable patient Radiofrequency catheter ablation (RFCA): For those tachycardia patients (SVT, VT, AF, AFL) Artificial cardiac pacing: For bradycardia, heart failure and malignant ventricular arrhythmia patients.

21 Sinus Arrhythmia

22 Sinus tachycardia Sinus rate > 100 beats/min (100-180) Causes:
Some physical condition: exercise, anxiety, exciting, alcohol, coffee Some disease: fever, hyperthyroidism, anemia, myocarditis Some drugs: Atropine, Isoprenaline Needn’t therapy

23 Sinus Bradycardia Sinus rate < 60 beats/min
Normal variant in many normal and older people Causes: Trained athletes, during sleep, drugs (ß-blocker) , Hypothyriodism, CAD or SSS Symptoms: Most patients have no symptoms. Severe bradycardia may cause dizziness, fatigue, palpitation, even syncope. Needn’t specific therapy, If the patient has severe symptoms, planted an pacemaker may be needed.

24 Sinus Arrest or Sinus Standstill
Sinus arrest or standstill is recognized by a pause in the sinus rhythm. Causes: myocardial ischemia, hypoxia, hyperkalemia, higher intracranial pressure, sinus node degeneration and some drugs (digitalis, ß-blocks). Symptoms: dizziness, amaurosis, syncope Therapy is same to SSS

25 Sinoatrial exit block (SAB)
SAB: Sinus pulse was blocked so it couldn’t active the atrium. Causes: CAD, Myopathy, Myocarditis, digitalis toxicity, et al. Symptoms: dizziness, fatigue, syncope Therapy is same to SSS

26 Sinoatrial exit block (SAB)
Divided into three types: Type I, II, III Only type II SAB can be recognized by EKG.

27 Sick Sinus Syndrome (SSS)
SSS: The function of sinus node was degenerated. SSS encompasses both disordered SA node automaticity and SA conduction. Causes: CAD, SAN degeneration, myopathy, connective tissue disease, metabolic disease, tumor, trauma and congenital disease. With marked sinus bradycardia, sinus arrest, sinus exit block or junctional escape rhythms Bradycardia-tachycardia syndrome

28 Sick Sinus Syndrome (SSS)
EKG Recognition: Sinus bradycardia, ≤40 bpm; Sinus arrest > 3s Type II SAB Nonsinus tachyarrhythmia ( SVT, AF or Af). SNRT > 1530ms, SNRTc > 525ms Instinct heart rate < 80bmp

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30 Sick Sinus Syndrome (SSS)
Therapy: Treat the etiology Treat with drugs: anti-bradycardia agents, the effect of drug therapy is not good. Artificial cardiac pacing.

31 Atrial arrhythmia

32 Premature contractions
The term “premature contractions” are used to describe non sinus beats. Common arrhythmia The morbidity rate is 3-5%

33 Atrial premature contractions (APCs)
APCs arising from somewhere in either the left or the right atrium. Causes: rheumatic heart disease, CAD, hypertension, hyperthyroidism, hypokalemia Symptoms: many patients have no symptom, some have palpitation, chest incomfortable. Therapy: Needn’t therapy in the patients without heart disease. Can be treated with ß-blocker, propafenone, moricizine or verapamil.

34 Atrial tachycardia Classify by automatic atrial tachycardia (AAT); intra-atrial reentrant atrial tachycardia (IART); chaotic atrial tachycardia (CAT). Etiology: atrial enlargement, MI; chronic obstructive pulmonary disease; drinking; metabolic disturbance; digitalis toxicity; electrolytic disturbance.

35 Atrial tachycardia May occur transient; intermittent; or persistent.
Symptoms: palpitation; chest uncomfortable, tachycardia may induce myopathy. Auscultation: the first heart sound is variable

36 Intra-atrial reentry tachycardia (IART)
ECG characters: Atrial rate is around bpm; P’ wave is different from sinus P wave; P’-R interval ≥ 0.12” Often appear type I or type II, 2:1 AV block; EP study: atrial program pacing can induce and terminate tachycardia

37 Automatic atrial tachycardia (AAT)
ECG characters: Atrial rate is around bpm; Warmup phenomena P’ wave is different from sinus P wave; P’-R interval≥ 0.12” Often appear type I or type II, 2:1 AV block; EP study: Atrial program pacing can’t induce or terminate the tachycardia

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39 Chaotic atrial tachycardia (CAT)
Also termed “Multifocal atrial tachycardia”. Always occurs in COPD or CHF, Have a high in-hospital mortality ( 25-56%). Death is caused by the severity of the underlying disease. ECG characters: Atrial rate is around bpm; The morphologies P’ wave are more than 3 types. P’-P’, P’-R and R-R interval are different. Will progress to af in half the cases EP study: Atrial program pacing can’t induce or terminate the tachycardia

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41 Therapy IRAT: Esophageal Pulsation Modulation, RFCA, Ic and IV class anti-tachycardia agents AAT: Digoxin, IV, II, Ia and III class anti-tachycardia agents; RFCA CAT: treat the underlying disease, verapamil or amiodarone. Associated with SSS: Implant pace-maker.

42 Atrial flutter Etiology:
It can occur in patients with normal atrial or with abnormal atrial. It is seen in rheumatic heart disease (mitral or tricuspid valve disease), CAD, hypertension, hyperthyroidism, congenital heart disease, COPD. Related to enlargement of the atria Most AF have a reentry loop in right atrial

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44 Atrial flutter Symptoms: depend on underlying disease, ventricular rate, the patient is at rest or is exerting With rapid ventricular rate: palpitation, dizziness, shortness of breath, weakness, faintness, syncope, may develop angina and CHF.

45 Atrial flutter Therapy: Treat the underlying disease
To restore sinus rhythm: Cardioversion, Esophageal Pulsation Modulation, RFCA, Drug (III, Ia, Ic class). Control the ventricular rate: digitalis. CCB, ß-block Anticoagulation

46 Atrial fibrillation Subdivided into three types: paroxysmal, persistent, permanent. Etiology: Morbidity rate increase in older patients Etiology just like atrial flutter Idiopathic Mechanism: Multiple wavelet re-entry; Rapid firing focus in pulmonary vein, vena cava or coronary sinus.

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48 Atrial fibrillation Manifestation:
Affected by underlying diseases, ventricular rate and heart function. May develop embolism in left atrial. Have high incidence of stroke. The heart rate, S1 and rhythm is irregularly irregular If the heart rhythm is regular, should consider about (1) restore sinus rhythm; (2) AF with constant the ratio of AV conduction; (3) junctional or ventricular tachycardia; (4) slower ventricular rate may have complete AV block.

49 Atrial fibrillation Therapy: Treat the underlying disease
Restore sinus rhythm: Drug, Cardioversion, RFCA, Maze surgery Rate control: digitalis. CCB, ß-block Antithrombotic therapy: Aspirine, Warfarin

50 Atrioventricular Junctional arrhythmia

51 Atrioventricular junctional premature contractions
Etiology and manifestation is like APCs Therapy the underlying disease Needn’t anti-arrhythmia therapy.

52 Nonparoxysmal AV junctional tachycardia
Mechanism: relate to hyper-automaticity or trigger activity of AV junctional tissue Etiology: digitalis toxicity; inferior MI; myocarditis; acute rheumatic fever and postoperation of valve disease ECG: the heart rate ranges bpm or more, regular, normal QRS complex, may occur AV dissociation and wenckebach AV block

53 Nonparoxysmal AV junctional tachycardia
Therapy: Treat underlying disease; stopping digoxin, administer potassium, lidocaine, phenytoin or propranolol. Not for DC shock It can disappear spontaneously. If had good tolerance, not require therapy.

54 Paroxysmal tachycardia
Most PSVT (paroxysmal supraventricular tachycardia) is due to reentrant mechanism. The incidence of PSVT is higher in AVNRT (atrioventricular node reentry tachycardia) and AVRT (atioventricular reentry tachycardia), the most common is AVNRT (90%) Occur in any age individuals, usually no structure heart disease.

55 Paroxysmal tachycardia
Manifestation: Occur and terminal abruptly. Palpitation, dizziness, syncope, angina, heart failure and shock. The sever degree of the symptom is related to ventricular rate, persistent duration and underlying disease

56 Paroxysmal tachycardia
ECG characteristic of AVNRT Heart rate is bpm, regular QRS complex is often normal, wide QRS complex is with aberrant conduction Negative P wave in II III aVF, buried into or following by the QRS complex. AVN jump phenomena

57 Paroxysmal tachycardia
ECG characteristic of AVRT Heart rate is bpm, regular In orthodromic AVRT, the QRS complex is often normal, wide QRS complex is with antidromic AVRT Retrograde P’ wave, R-P’>110ms.

58 Paroxysmal tachycardia
Therapy: AVNRT & orthodromic AVRT Increase vagal tone: carotid sinus massage, Valsalva maneuver.if no successful, Drug: verapamil, adrenosine, propafenone DC shock Antidromic AVRT: Should not use verapamil, digitalis, and stimulate the vagal nerve. Drug: propafenone, sotalol, amiodarone RFCA

59 Pre-excitation syndrome (W-P-W syndrome)
There are several type of accessory pathway Kent: adjacent atrial and ventricular James: adjacent atrial and his bundle Mahaim: adjacent lower part of the AVN and ventricular Usually no structure heart disease, occur in any age individual

60 WPW syndrome Manifestation: Palpitation, syncope, dizziness
Arrhythmia: 80% tachycardia is AVRT, 15-30% is AFi, 5% is AF, May induce ventricular fibrillation

61 WPW syndrome Therapy: Pharmacologic therapy: orthodrome AVRT or associated AF, AFi, may use Ic and III class agents. Antidromic AVRT can’t use digoxin and verapamil. DC shock: WPW with SVT, AF or Afi produce agina, syncope and hypotension RFCA

62 Ventricular arrhythmia

63 Ventricular Premature Contractions (VPCs)
Etiology: Occur in normal person Myocarditis, CAD, valve heart disease, hyperthyroidism, Drug toxicity (digoxin, quinidine and anti-anxiety drug) electrolyte disturbance, anxiety, drinking, coffee

64 VPCs Manifestation: palpitation dizziness syncope
loss of the second heart sound

65 PVCs Therapy: treat underlying disease, antiarrhythmia
No structure heart disease: Asymptom: no therapy Symptom caused by PVCs: antianxiety agents, ß-blocker and mexiletine to relief the symptom. With structure heart disease (CAD, HBP): Treat the underlying diseas ß-blocker, amiodarone Class I especially class Ic agents should be avoided because of proarrhytmia and lack of benefit of prophylaxis

66 Ventricular tachycardia
Etiology: often in organic heart disease CAD, MI, DCM, HCM, HF, long QT syndrome Brugada syndrome Sustained VT (>30s), Nonsustained VT Monomorphic VT, Polymorphic VT

67 Ventricular tachycardia
Torsades de points (Tdp): A special type of polymorphic VT, Etiology: congenital (Long QT), electrolyte disturbance, antiarrhythmia drug proarrhythmia (IA or IC), antianxiety drug, brain disease, bradycardia

68 Ventricular tachycardia
Accelerated idioventricular rhythm: Related to increase automatic tone Etiology: Often occur in organic heart disease, especially AMI reperfusion periods, heart operation, myocarditis, digitalis toxicity

69 VT Manifestation: Nonsustained VT with no symptom
Sustained VT : with symptom and unstable hemodynamic, patient may feel palpitation, short of breathness, presyncope, syncope, angina, hypotension and shock.

70 VT ECG characteristics:
Monomorphic VT: bpm, occur and terminate abruptly,regular Accelerated idioventricular rhythm: a runs of ventricular beats, rate of bpm, tachycardia is a capable of warm up and close down, often seen AV dissociation, fusion or capture beats Tdp: rotation of the QRS axis around the baseline, the rate from bpm, QT interval prolonged > 0.5s, marked U wave

71 Treatment of VT Treat underlying disease
Cardioversion: Hemodynamic unstable VT (hypotension, shock, angina, CHF) or hemodynamic stable but drug was no effect Pharmacological therapy: ß-blockers, lidocain or amiodarone RFCA, ICD or surgical therapy

72 Therapy of Special type VT
Accelerated idioventricular rhythm: usually no symptom, needn’t therapy. Atropine increased sinus rhythm Tdp: Treat underlying disease, Magnesium iv, atropine or isoprenaline, ß-block or pacemaker for long QT patient temporary pacemaker

73 Ventricular flutter and fibrillation
Often occur in severe organic heart disease: AMI, ischemia heart disease Proarrhythmia (especially produce long QT and Tdp), electrolyte disturbance Anaesthesia, lightning strike, electric shock, heart operation It’s a fatal arrhythmia

74 Ventricular flutter and fibrillation
Manifestation: Unconsciousness, twitch, no blood pressure and pulse, going to die Therapy: Cardio-Pulmonary Resuscitate (CPR) ICD

75 Cardiac conduction block
Block position: Sinoatrial; intra-atrial; atrioventricular; intra-ventricular Block degree Type I: prolong the conductive time Type II: partial block Type III: complete block

76 Atrioventricular Block
AV block is a delay or failure in transmission of the cardiac impulse from atrium to ventricle. Etiology: Atherosclerotic heart disease; myocarditis; rheumatic fever; cardiomyopathy; drug toxicity; electrolyte disturbance, collagen disease, lev’s disease.

77 AV Block AV block is divided into three categories:
First-degree AV block Second-degree AV block: further subdivided into type I and type II Third-degree AV block: complete block

78 AV Block Manifestations: First-degree AV block: almost no symptoms;
Second degree AV block: palpitation, fatigue Third degree AV block: Dizziness, agina, heart failure, lightheadedness, and syncope may cause by slow heart rate, Adams-Stokes Syndrome may occurs in sever case. First heart sound varies in intensity, will appear booming first sound

79 AV Block Treatment: I or II degree AV block needn’t antibradycardia agent therapy II degree II type and III degree AV block need antibradycardia agent therapy Implant Pace Maker

80 Intraventricular Block
Intraventricular conduction system: Right bundle branch Left bundle branch Left anterior fascicular Left posterior fascicular

81 Intraventricular Block
Etiology: Myocarditis, valve disease, cardiomyopathy, CAD, hypertension, pulmonary heart disease, drug toxicity, Lenegre disease, Lev’s disease et al. Manifestation: Single fascicular or bifascicular block is asymptom; tri-fascicular block may have dizziness; palpitation, syncope and Adams-stokes syndrome

82 Intraventricular Block
Therapy: Treat underlying disease If the patient is asymptom; no treat, bifascicular block and incomplete trifascicular block may progress to complete block, may need implant pace maker if the patient with syncope


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