tachycardia
TACHYCARDIA

Tachycardia or tachyarrhythmia is having a heart rate of >100 beats/min.

Divided into supreventricular and ventricular tachycardia.

Signs and symptoms related to rapid heart rate are altered sensorium, angina, shortness of breath, myocardial infarction, hypotension and other signs of shock (eg cold clammy skin, low urine output), heart failure or pulmonary congestion.

Electrical Cardioversion

Synchronized Electrical Cardioversion

  • Delivered in time (synchronized) with the QRS complex
  • Recommended in unstable conditions of supraventricular tachycardia (SVT) due to pre-excitation, re-entry (atrioventricular nodal reentrant tachycardia [AVNRT], atrioventricular reentrant tachycardia [AVRT]), focal atrial tachycardia, atrial fibrillation, atrial flutter & regular/sustained ventricular tachycardia (VT)
  • May be considered in patients who are unresponsive or with contraindications to pharmacological therapy
    • Considered in atrioventricular nodal reentrant tachycardia (AVNRT) & hemodynamically stable patients with atrioventricular reentrant tachycardia (AVRT) when unresponsive or with contraindications to vagal maneuvers & Adenosine therapy
  • Do not attempt electric or pharmacologic cardioversion in patients w/ atrial fibrillation at risk for cardioemboli, unless the patient is unstable or there is documented absence of left atrial thrombus by transesophageal echocardiogram (TEE)
  • Shock dose used is lower than dose used for unsynchronized shocks (ie energy used for attempted defibrillation)
  • Conscious patients should be anesthetized or sedated prior to cardioversion
  • Cardioversion will not prevent subsequent arrhythmias & can trigger thromboembolism
  • Serial shocks are inappropriate for self-terminating atrial fibrillation that recur within hours or days (recurrent paroxysmal atrial fibrillation)
  • Recurrent episodes must be treated with drugs

Recommended Initial Dose for Cardioversion:

  • Regular narrow-complex tachycardia: 50-100 J
  • Irregular narrow-complex tachycardia: 120-200 J biphasic or 200 J monophasic
  • Regular wide-complex tachycardia: 100 J
  • Irregular wide-complex tachycardia: unsynchronized defibrillation dose
  • Atrial fibrillation: 120-200 J w/ biphasic waveform; 200 J monophasic waveform
  • Atrial flutter & other SVTs: 50-100 J monophasic damped sine (MDS) waveform
  • Monophasic ventricular tachycardia (VT): 100 J monophasic waveform
    • Increase subsequent shock doses as needed
  • Polymorphic ventricular tachycardia (VT): treat as ventricular fibrillation with high energy unsynchronized shocks
Unsynchronized Electrical Cardioversion
  • If cardiac rhythm is irregular & it is not possible to synchronize a shock, use high-energy unsynchronized shocks (dose for defibrillation)

Pharmacotherapy

  • Pharmacotherapy is not recommended for maintenance of sinus rhythm in patients with advanced atrioventricular node dysfunction or sinus node disease unless they have a functioning cardiac pacemaker
  • Before starting therapy with antiarrhythmic agents, it is recommended to focus treatment on precipitating or reversible causes of atrial fibrillation
  • Therapy with a particular antiarrhythmic drug is not recommended in patients with atrial fibrillation who have risk factors for proarrhythmia with that drug
  • Patients with atrial fibrillation can benefit from pharmacotherapy to maintain sinus rhythm & to prevent tachycardia-induced cardiomyopathy

Adenosine

  • An endogenous purine nucleotide
  • More rapid action with fewer side effects than Verapamil in converting supraventricular tachycardia (SVT)
  • May be used in paroxysmal supraventricular tachycardia (SVT) with re-entrant circuits [including atrioventricular nodal reentrant tachycardia (AVNRT) & orthodromic atrioventricular reentrant tachycardia (AVRT)], & focal atrial tachycardia
    • Used both as therapeutic & diagnostic drug (for atrial flutter & atrial fibrilllation)
    • Favorable response to Adenosine favors likelihood of re-entry SVT
  • Also used in stable, wide-complex tachycardias with recurrence of a known re-entry pathway
  • Acts to delay transmission across the atrioventricular (AV) & sinus node
    • May reveal underlying atrial rhythms by slowing the ventricular response in narrow-complex atrioventricular (AV) nodal or sinus nodal re-entry tachycardia
  • Contraindicated in irregular narrow-complex tachycardias & atrial fibrillation

Antiarrhythmic Agents - Class Ia

Disopyramide

  • Recommended for sinus rhythm control in patients with atrial fibrillation
  • May be used for patients with ventricular tachycardia & premature ventricular contractions

Procainamide HCl

  • May be used for treatment of stable monomorphic ventricular tachycardia in patients with preserved function
  • May be used for control of cardiac rhythm in atrial fibrillation or atrial flutter in patients with known pre-excitation Wolff-Parkinson White (WPW) syndrome & preserved ventricular function
  • For atrioventricular (AV) reentrant, narrow-complex tachycardias with preserved ventricular function (eg re-entry supraventricular tachycardia) if Adenosine & vagal maneuvers fail
  • IV doses may be used for acute junctional tachycardia when treatment with beta-blockers fail
  • Action: Delays conduction in myocardial tissue

Antiarrhythmic Agents - Class Ib

Lidocaine

  • May be considered for, but not the drug of choice for:
    • Stable monomorphic VT in patients with preserved ventricular function
    • Polymorphic ventricular tachycardia (VT) with normal baseline QT interval
    • Polymorphic ventricular tachycardia (VT) with a prolonged baseline QT interval that suggests torsades de pointes

Mexiletine

  • May be used for patients with ventricular tachycardia & long QT syndrome type 3
  • Treatment option for patients with sustained ventricular tachycardia or after cardiac arrest when unresponsive to Amiodarone therapy

Quinidine

  • Recommended for sinus rhythm control in patients with atrial fibrillation
  • May be used for patients with ventricular tachycardia, ventricular fibrillation, short QT syndrome, & Brugada syndrome unresponsive to beta-blockers or Amiodarone

Antiarrhythmic Agents - Class Ic

Flecainide, Propafenone

  • Recommended for patients with atrial fibrillation for cardiac rate & rhythm control
  • Used for pharmacological cardioversion of patients with atrial flutter or atrial fibrillation
  • May be used for patients with symptomatic supraventricular tachycardia (SVT) [focal atrial tachycardia, atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia (AVRT) with pre-excited atrial fibrillation, junctional tachycardia], atrial fibrillation, ventricular tachycardia & premature ventricular contractions, or symptomatic recurrent atrial flutter without structural or ischemic heart disease who are not undergoing catheter ablation or those unresponsive/intolerant to beta-blockers & nondihydropyridine calcium antagonists
  • Oral doses may be considered for chronic orthodromic atrioventricular nodal reentrant tachycardia (AVNRT)

Antiarrhythmic Agents - Class III

Amiodarone

  • Decreases AV conduction & sinus node function
  • Preferred over other antiarrhythmics for atrial & ventricular arrhythmias in patients who have severely impaired cardiac function
  • IV doses are recommended for heart rate control in critically-ill atrial fibrillation patients without pre-excitation & in hemodynamically stable patients with focal atrial tachycardia & atrial flutter without pre-excitation
  • Recommended antiarrhythmic drug for rhythm control in paroxysmal/persistent atrial fibrillation
  • May be used for treatment of stable monomorphic ventricular tachycardia (VT), polymorphic ventricular tachycardia (VT) with normal QT interval, & sustained recurrent monomorphic ventricular tachycardia
  • Used in patients with stable narrow-complex regular & irregular tachycardias
  • Considered in patients with atrial flutter with heart failure or underlying heart disease
  • May be considered in post-op patients to reduce the risk of developing atrial fibrillation
  • Oral doses are used for pharmacological cardioversion of patients with atrial flutter or atrial fibrillation & in chronic orthodromic atrioventricular nodal reentrant tachycardia (AVNRT)
  • Adrenergic antagonist (alpha & beta)
    • Affects Na, K & Ca channels prolonging action potential & refractory period in myocardial tissue

Dofetilide

  • Recommended for patients with atrial fibrillation for cardiac rate & rhythm control
  • Used for pharmacological cardioversion of patients with atrial fibrillation or atrial flutter to control rhythm
  • May also be used for patients with symptomatic SVT [atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia (AVRT) with or without pre-excited atrial fibrillation] without structural or ischemic heart disease who are not undergoing catheter ablation & unresponsive/intolerant to beta-blockers, Diltiazem, Flecainide, Propafenone, or Verapamil
  • Not recommended as an outpatient medication; may increase risk of torsades de pointes & altered renal function

Dronedarone

  • A non-iodinated derivative of Amiodarone, modified to reduce toxicities associated with Amiodarone use
  • Approved treatment option for clinically stable patients with history of, or current non-permanent atrial fibrillation, to prevent recurrence of atrial fibrillation & to lower ventricular rate
  • Also recommended for maintenance of sinus rhythm post-cardioversion in patients with paroxysmal/persistent atrial fibrillation unresponsive to 1st-line agents, no left ventricular systolic dysfunction & previous or current heart failure, & with at least one of the following: diabetes mellitus, hypertension with ongoing 2 maintenance therapies, history of transient ischemic attack, cerebrovascular accident or ischemic attack/stroke/systemic embolism, left atrial diameter of >50 mm, or age >70 years
  • Patients receiving Dronedarone should receive appropriate antithrombotic treatment
  • Has been shown to prolong the time to recurrence, slow ventricular rate, improves cardiac rate during exercise & reduce hospitalizations in patients with atrial fibrillation
  • Patients with permanent atrial fibrillation who are on Dronedarone have increased risk of serious cardiovascular events (eg death, stroke, heart failure)
  • Inhibits potassium currents, thus prolonging cardiac action potential & refractory periods (Class III); inhibits sodium currents (Class Ib) & calcium currents (Class IV); also inhibits adrenergic activities non-competitively (Class II)

Ibutilide

  • May be used for acute rhythm conversion of atrial fibrillation or atrial flutter of ≤48 hr duration in patients with normal cardiac function, with Wolff-Parkinson White (WPW) syndrome & preserved ventricular function
  • Used for rate control in atrial fibrillation or atrial flutter in patients with preserved ventricular function unresponsive to Ca antagonists or beta-blockers
  • Treatment option used to restore sinus rhythm in hemodynamically stable patients with focal atrial tachycardia & pre-excited atrial fibrillation
  • Increases the duration of action potential & prolongs the refractory period of cardiac tissue

Anticoagulants

  • Recommended for non-valvular atrial fibrillation patients at high risk for systemic embolism & stroke
  • Depends on the presence of risk factors (past medical history of stroke, TIA or systemic embolism, CHA2DS2-VASc score of ≥2, LVEF <40%, symptomatic heart failure, ≥75 years of age or >65 years with comorbidities)
  • Anticoagulation in patients experiencing atrial flutter/atrial fibrillation for <48 hours depend upon the thromboembolic risk
    • IV Heparin, low molecular weight Heparin (LMWH), or newer oral anticoagulants (NOACs) is recommended for patients with high stroke risk
    • Cardioversion w/ IV Heparin, LMWH, or NOACs or no antithrombotics may be considered for patients w/ low thromboembolic risk
  • Should be used w/ caution when used concomitantly w/ nondihydropyridine calcium antagonists

Novel Oral Anticoagulants (NOACs)

  • Eg Apixaban, Dabigatran, Edoxaban, Rivaroxaban
  • Newer anticoagulants preferred over VKAs for their lesser adverse effects
  • Dabigatran is a direct thrombin inhibitor recommended for patients w/ at least one risk factor for stroke
  • Apixaban, Edoxaban, & Rivaroxaban are direct factor Xa inhibitors approved for the prevention of stroke & systemic embolism in patients w/ non-valvular A-fib
  • Alternative treatment for patients unable to tolerate the side effects of VKAs or to undergo INR monitoring

Vitamin K Antagonists (VKAs)

  • Eg Warfarin
  • Prophylactic treatment of choice for patients w/ atrial fibrillation w/ mechanical heart valves & atrial flutter
  • INR monitoring weekly at the start of treatment & monthly thereafter is required during treatment

Beta-Blockers (Antiarrhythmic Agents - Class II)

  • Eg Atenolol, Bisoprolol, Carvedilol, Esmolol, Labetalol, Metoprolol, Nadolol, Nebivolol, Propranolol
  • Used in hemodynamically stable patients w/ preserved ventricular function & narrow-complex regular tachycardias that originate from a re-entry mechanism (re-entry SVT, AVNRT, orthodromic AVRT w/ pre-excitation on resting ECG), an automatic focus (junctional, ectopic or multifocal tachycardia) not controlled by vagal maneuvers & Adenosine, or recurrent polymorphic ventricular tachycardias (Torsades de pointes)
  • IV doses are recommended for acute atrial fibrillation, symptomatic junctional tachycardia, hemodynamically stable atrial flutter, & left ventricle fascicular ventricular tachycardia; oral doses may be used for rate control in patients w/ chronic atrial fibrillation & hemodynamically stable atrial flutter
    • IV doses may be considered for hemodynamically stable patients w/ focal atrial tachycardia
    • IV Metoprolol may be used for rate control in patients w/ MAT
  • Lowers HR & BP; decreases the effects of circulating catecholamines; effective rate-controlling agent
  • May be used as maintenance therapy in patients w/ symptomatic IST
  • Not to be used in patients w/ ventricular tachycardia, pre-excited atrial fibrillation, or systolic heart failure

Sotalol

  • Has nonselective beta-blocking actions & antiarrhythmic agent class III properties
  • Has been shown to decrease post-operative atrial fibrillation
  • May be used to control rhythm in atrial fibrillation or atrial flutter ≤48 hr in patients w/ pre-excitation (WPW) syndrome & preserved ventricular function
  • May be used in stable monomorphic VT, focal atrial tachycardia, & in patients w/ symptomatic SVT (AVNRT, AVRT w/ or w/o pre-excited atrial fibrillation) who are not undergoing catheter ablation
  • Action: Prolongs the duration of action potential & increases cardiac tissue refractoriness

Digoxin

  • Alternative agent for rate control
  • May be useful in patients w/ systolic CHF or hypotension in whom beta-blockers & Ca channel blockers are contraindicated & in patients w/ symptomatic SVT w/o pre-excitation who prefer not to undergo or are not qualified for catheter ablation
  • Combination w/ other agents is often necessary to achieve adequate rate control
  • Exerts positive inotropic effect w/o lowering BP
  • Should not be given to patients w/ AVRT or atrial fibrillation w/ pre-excitation on resting ECG

Ivabradine

  • May be used in patients w/ IST to help control sinus rate & IST symptoms
  • Inhibits If channels for normal sinus node automaticity

Magnesium

  • Recommended for the treatment of torsades de pointes VT w/ or w/o cardiac arrest

Nondihydropyridine Calcium Antagonists (Antiarrhythmic Agents - Class IV)

  • Eg Verapamil, Diltiazem
  • Terminates reentrant arrhythmias & control ventricular response in atrial (focal & multifocal) tachycardias
    • Control cardiac rate in patient w/ preserved ventricular function & atrial fibrillation or atrial flutter when the duration of the arrhythmia is <48 hr
  • Used in stable regular narrow-complex tachycardias that failed to convert or uncontrolled by Adenosine or vagal maneuvers
  • May be used for patients w/ acute orthodromic AVRT w/ pre-excitation on resting ECG if unresponsive to other treatments, or junctional tachycardia as initial therapy if unresponsive to beta blockers
  • Verapamil must be given only to hemodynamically stable patients w/ narrow-complex reentry/paroxysmal SVT, arrhythmias of supraventricular origin, & for acute ventricular rate control in patients w/ atrial fibrillation
  • IV Verapamil is recommended for patients w/ left ventricular fascicular ventricular tachycardia
  • Delay conduction & increase refractoriness in the AV node
  • Avoid use in patients w/ LV systolic dysfunction, pre-excited atrial fibrillation, & decompensated heart failure

Vernakalant

  • Inhibits both atrial sodium & potassium repolarising currents; classified as both antiarrhythmic agent class I & III
  • IV doses may be used for pharmacological cardioversion in hemodynamically stable recent-onset atrial fibrillation patients w/ coronary artery disease or heart failure

Non-Pharmacological Therapy

  • Vagal maneuvers alone will terminate up to 25% of re-entry SVT
  • Record an ECG during each vagal maneuver
  • If cardiac rhythm exhibits atrial flutter, slowing of the ventricular response will occur w/ vagal maneuver & display flutter waves
  • Vagal maneuvers (or Adenosine) often will suppress (AVNRT & orthodromic AVRT) within seconds

Valsalva Maneuver

  • Forced expiration against a closed glottis raises intrathoracic pressure to at least 30-40 mmHg
    • When done in the supine position may be most efficacious
  • Stimulation of the baroreceptors in the aorta induces vagal nerve stimulation & halt of sympathetic stimulation, which leads to a decrease in sinoatrial node activity & AV node conduction

Carotid Sinus Massage

  • 5-10 sec pressure w/ circular motion applied on the carotid artery (1 side) at the level of the cricoid cartilage
  • Contraindicated in patients w/ carotid artery disease or carotid bruit on examination
  • Use w/ caution in the elderly & in patients w/ prior stroke
  • Stimulates the baroreceptors resulting in a reflex increase in vagus nerve activity
  • Slows AV node conduction

Others

  • Application of an ice pack on the face may help relieve symptoms but further studies are needed to prove its use in tachyarrhythmias
  • Elicit oculocardiac reflex by applying non-rotating pressure on the eyeball over closed eyelid for 10-20 sec
  • Avoidance of stimulants such as caffeine, alcohol, tobacco, medications (cough & cold preparations, beta-agonists), & recreational drugs (amphetamine, cocaine) may help prevent recurrence of sinus tachycardia
  • Appropriate hydration is encouraged for patients w/ signs of dehydration or febrile states

Ablation

  • Treatment option for patients who experience treatment failure after pharmacological therapies or for patients w/ paroxysmal atrial fibrillation who prefer interventional treatment
  • Catheter ablation is preferred over surgical ablation because of significantly increased complications after surgical ablation

Catheter Ablation

  • Alternative treatment option for patients w/ symptomatic focal atrial tachycardia, recurrent atrial flutter, junctional tachycardia, recurrent symptomatic SVT in patients w/ adult congenital heart disease, paroxysmal or persistent atrial fibrillation, & short-coupled Torsades de pointes
  • Recommended for patients w/ scar-related cardiac disease w/ incessant ventricular tachycardia, or ischemic heart disease & recurrent implantable cardioverter defibrillator (ICD) shocks due to sustained ventricular tachycardia
    • May be considered in patients w/ ischemic heart disease & ICD after 1st episode of sustained ventricular tachycardia
  • Recommended 1st-line treatment for patients w/ symptomatic AVNRT w/ ongoing treatments using the slow-pathway technique
  • Patients w/ chronic AVNRT, pre-excitation atrial fibrillation, & patients w/ WPW syndrome may benefit from catheter ablation of the accessory pathway
  • May be used for patients w/ atrial flutter involving the CTI who are symptomatic or unresponsive to pharmacological therapies, & non-CTI dependent atrial flutter w/ treatment failure after treatment w/ at least 1 antiarrhythmic agent

Surgical Ablation

  • May be considered in patients w/ severe cases of inappropriate sinus tachycardia, ventricular tachycardia, persistent atrial fibrillation & in atrial fibrillation/atrial flutter patients w/ adult congenital heart disease undergoing scheduled surgical repair
  • May be done during cardiac surgery in patients w/ persistent ventricular tachycardia/flutter even after catheter ablation

Radiofrequency Ablation

  • Used to reduce sinus rate in patients w/ inappropriate sinus tachycardia
  • Most commonly used electrical ablation source for paroxysmal atrial fibrillation
  • May be used in patients w/ recurrent ventricular tachycardia & ventricular fibrillation, followed by ICD implantation, despite pharmacological treatment &/or revascularization

Atrioventricular (AV) Node Ablation & Pacemaker Implantation

  • May be considered in patients w/ symptomatic patients w/ permanent atrial fibrillation despite pharmacological treatments & other interventions or left ventricular dysfunction secondary to high ventricular rates
  • Results in complete AV nodal blockage

Implantable Cardioverter Defibrillator (ICD)

  • Recommended in patients w/ documented ventricular fibrillation or hemodynamically unstable ventricular tachycardia
  • May be considered in patients w/ recurrent sustained ventricular tachycardia >48 hr after MI
    • Reduces the risk of sudden cardiac death in patients w/ symptomatic heart failure, left ventricular dysfunction, & heart transplant candidates
  • Implantation may be commenced subcutaneously or via transvenous route
  • External defibrillators (wearable cardioverter defibrillators) should be considered in patients w/ poor left ventricular systolic function at increased risk of sudden arrhythmic death who cannot tolerate implantable types of defibrillators

Overdrive Pacing (Anti-Tachycardia Pacing)

  • For patients w/ an implantable cardiac device
  • May be considered in patients w/ focal atrial tachycardia & recurrent atrial tachycardia, refractory ventricular tachycardia w/ enhanced automaticity, Digoxin-induced tachycardia, & Torsades de pointes to prevent recurrences
  • Atrial pacing may be used for acute conversion of atrial flutter; type of pacing will depend on patient’s comorbidities
  • May be considered in recurrent ventricular tachycardia unresponsive to pharmacological therapy & catheter ablation
    • Produces better prognosis compared to treatment w/ antiarrhythmic agents
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