tachycardia
TACHYCARDIA

Tachycardia or tachyarrhythmia is used to describe the presence of cardiac rhythm abnormality in states when cardiac rate is increased to >100 bpm.

Divided into supraventricular 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 and regular/sustained ventricular tachycardia (VT)
  • May be considered in patients who are unresponsive or with contraindications to pharmacological therapy
    • May be considered in AVNRT and hemodynamically stable patients with AVRT when unresponsive or with contraindications to vagal maneuvers and Adenosine therapy
    • May also be considered in hemodynamically unstable patients with focal atrial tachycardia
  • Do not attempt electric or pharmacologic cardioversion in patients with 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 and 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 with biphasic waveform; 200 J monophasic waveform
  • Atrial flutter and 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 VT: Treat as ventricular fibrillation with high energy unsynchronized shocks
Unsynchronized Electrical Cardioversion
  • If cardiac rhythm is irregular and 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 and to prevent tachycardia-induced cardiomyopathy

Adenosine

  • An endogenous purine nucleotide
  • More rapid action with fewer side effects than Verapamil in converting SVT
  • May be used in paroxysmal SVT with re-entrant circuits (including AVNRT and orthodromic AVRT), and focal atrial tachycardia
    • Used both as therapeutic and diagnostic drug (for atrial flutter and 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) and sinus node
    • May reveal underlying atrial rhythms by slowing the ventricular response in narrow-complex AV nodal or sinus nodal re-entry tachycardia
  • Contraindicated in irregular narrow-complex tachycardias and atrial fibrillation
  • Contraindicated in unstable or irregular or polymorphic wide-complex tachycardia

Antiarrhythmic Agents - Class Ia

Disopyramide

  • May be used for sinus rhythm control in patients with vagally mediated atrial fibrillation and with hypertrophic obstructive cardiomyopathy
  • May be used for patients with VT and premature ventricular contractions

Procainamide HCl

  • May be used for treatment of stable monomorphic VT 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 and preserved ventricular function
  • For AV reentrant, narrow-complex tachycardias with preserved ventricular function (eg re-entry SVT) if Adenosine and vagal maneuvers fail
  • Intravenous (IV) doses may be used for acute junctional tachycardia when treatment with beta-blockers fail
  • Action: Delays conduction in myocardial tissue

Quinidine

  • Alternative therapy for sinus rhythm control in patients with atrial fibrillation, when other antiarrhythmic drugs cannot be used
  • May be used for patients with ventricular tachycardia, ventricular fibrillation, short QT syndrome, and Brugada syndrome unresponsive to beta-blockers or Amiodarone

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 VT with normal baseline QT interval
    • Polymorphic VT with a prolonged baseline QT interval that suggests torsades de pointes

Mexiletine

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

Antiarrhythmic Agents - Class Ic

Flecainide, Propafenone

  • Recommended for patients with atrial fibrillation for cardiac rate and rhythm control
  • Used for pharmacological cardioversion of patients with atrial flutter or atrial fibrillation
  • May be used for patients with symptomatic SVT (focal atrial tachycardia, AVNRT, AVRT with pre-excited atrial fibrillation, junctional tachycardia), atrial fibrillation, ventricular tachycardia and 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 and nondihydropyridine calcium antagonists
  • Oral doses may be considered for chronic orthodromic AVNRT

Antiarrhythmic Agents - Class III

Amiodarone

  • Decreases AV conduction and sinus node function
  • Preferred over other antiarrhythmics for atrial and 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 and in hemodynamically stable patients with focal atrial tachycardia and atrial flutter without pre-excitation and in patients with AVNRT unresponsive or intolerant to other therapies
  • Recommended antiarrhythmic drug for rhythm control in paroxysmal/persistent atrial fibrillation
  • May be used for treatment of stable monomorphic VT, polymorphic VT with normal QT interval, and sustained recurrent monomorphic VT
  • Used in patients with stable narrow-complex regular and 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 and in chronic orthodromic AVNRT
  • Adrenergic antagonist (alpha and beta)
    • Affects sodium, potassium and calcium channels prolonging action potential and refractory period in myocardial tissue
  • Should not be given to patients with atrial fibrillation with pre-excitation on resting electrocardiogram (ECG)

Dofetilide

  • Recommended for patients with atrial fibrillation for cardiac rate and 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 (AVNRT, AVRT with or without pre-excited atrial fibrillation) without structural or ischemic heart disease who are not undergoing catheter ablation and unresponsive/intolerant to beta-blockers, Diltiazem, Flecainide, Propafenone, or Verapamil
  • Not recommended as an outpatient medication; may increase risk of torsades de pointes and 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 and to lower ventricular rate
  • Also recommended for maintenance of sinus rhythm post-cardioversion in patients with paroxysmal/persistent atrial fibrillation unresponsive to first-line agents, no left ventricular systolic dysfunction and previous or current heart failure, and 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, improve cardiac rate during exercise and reduce hospitalizations in patients with atrial fibrillation
  • Patients with permanent atrial fibrillation should not be given Dronedarone due to increased risk of serious cardiovascular events (eg death, stroke, heart failure)
  • Inhibits potassium currents, thus prolonging cardiac action potential and refractory periods (Class III); inhibits sodium currents (Class Ib) and 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 hours duration in patients with normal cardiac function, with WPW syndrome and preserved ventricular function
  • Used for rate control in atrial fibrillation or atrial flutter in patients with preserved ventricular function unresponsive to Calcium antagonists or beta-blockers
  • Treatment option used to restore sinus rhythm in hemodynamically stable patients with focal atrial tachycardia and pre-excited atrial fibrillation
  • Increases the duration of action potential and prolongs the refractory period of cardiac tissue

Anticoagulants

  • Recommended for non-valvular atrial fibrillation patients at high risk for systemic embolism and stroke
  • Assess for the presence of risk factors (bleeding, past medical history of stroke, TIA or systemic embolism, CHA2DS2-VASc score of ≥2,left ventricular ejection fraction [LVEF] <40%, symptomatic heart failure, ≥75 years of age or >65 years with comorbidities) prior to initiation of anticoagulant therapy
  • 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 with IV Heparin, LMWH, or NOACs or no antithrombotics may be considered for patients with low thromboembolic risk
  • Should be used with caution when used concomitantly with nondihydropyridine calcium antagonists and antiplatelet therapy

Novel Oral Anticoagulants (NOACs)

  • Eg Apixaban, Dabigatran, Edoxaban, Rivaroxaban
  • Newer anticoagulants preferred over vitamin K antagonists (VKAs) for their lesser adverse effects and rapid onset of action
    • Preferred anticoagulants for stroke prevention in non-valvular atrial fibrillation
  • Dabigatran is a direct thrombin inhibitor recommended for patients with at least one risk factor for stroke
  • Apixaban, Edoxaban, and Rivaroxaban are direct factor Xa inhibitors approved for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation
  • Alternative treatment for patients unable to tolerate the side effects of VKAs or to undergo international normalized ratio (INR) monitoring

Vitamin K Antagonists (VKAs)

  • Eg Warfarin
  • Prophylactic treatment of choice for patients with atrial fibrillation with mechanical heart valves and atrial flutter
  • INR monitoring weekly at the start of treatment and 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 with preserved ventricular function and narrow-complex regular tachycardias that originate from a re-entry mechanism (re-entry SVT, AVNRT, orthodromic AVRT with pre-excitation on resting ECG), an automatic focus (junctional, ectopic or multifocal tachycardia) not controlled by vagal maneuvers and Adenosine, or recurrent polymorphic VTs (torsades de pointes)
  • IV doses are recommended for acute atrial fibrillation, symptomatic junctional tachycardia, hemodynamically stable atrial flutter, and left ventricle fascicular ventricular tachycardia; oral doses may be used for rate control in patients with chronic atrial fibrillation and hemodynamically stable atrial flutter
    • IV doses may be considered for hemodynamically stable patients with focal atrial tachycardia
    • IV Metoprolol may be used for rate control in patients with MAT in the absence of pulmonary disease
  • Lowers heart rate (HR) and blood pressure (BP); decreases the effects of circulating catecholamines; effective rate-controlling agent
  • May be used as maintenance therapy in patients with symptomatic inappropriate sinus tachycardia (IST)
  • Not to be used in patients with VT, pre-excited atrial fibrillation, or systolic heart failure

Sotalol

  • Has nonselective beta-blocking actions and 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 hours in patients with pre-excitation (WPW) syndrome and preserved ventricular function
  • May be used in stable monomorphic VT, focal atrial tachycardia, and in patients with symptomatic SVT (AVNRT, AVRT with or without pre-excited atrial fibrillation) who are not undergoing catheter ablation
  • May be an option to prevent recurrent atrial fibrillation
  • Can be used in patients with ischemic heart disease or structural disease unlike Flecainide and Propafenone
  • Action: Prolongs the duration of action potential and increases cardiac tissue refractoriness

Digoxin

  • Alternative agent for rate control
  • May be useful in patients with systolic CHF or hypotension in whom beta-blockers and Calcium channel blockers are contraindicated and in patients with symptomatic SVT without pre-excitation who prefer not to undergo or are not qualified for catheter ablation
  • Combination with other agents is often necessary to achieve adequate rate control
  • Exerts positive inotropic effect without lowering BP
  • Should not be given to patients with AVRT or atrial fibrillation with pre-excitation on resting ECG

Ivabradine

  • May be used in patients with IST to help control sinus rate and IST symptoms
  • Can be combined with a beta-blocker to manage patients with IST
  • Inhibits If channels for normal sinus node automaticity

Magnesium

  • Recommended for the treatment of torsades de pointes VT with or without cardiac arrest

Nondihydropyridine Calcium Antagonists (Antiarrhythmic Agents - Class IV)

  • Eg Verapamil, Diltiazem
  • Terminates reentrant arrhythmias and control ventricular response in atrial (focal and multifocal) tachycardias
    • Control cardiac rate in patient with preserved ventricular function and atrial fibrillation or atrial flutter when the duration of the arrhythmia is <48 hours
    • Treatment option for patients with MAT and pulmonary disease
  • Used in stable regular narrow-complex tachycardias that failed to convert or uncontrolled by Adenosine or vagal maneuvers
  • May be used for patients with acute orthodromic AVRT with pre-excitation on resting ECG if unresponsive to other treatments, or junctional tachycardia as initial therapy if unresponsive to beta blockers
  • Treatment option for patients with AVNRT who are not undergoing catheter ablation
  • Verapamil must be given only to hemodynamically stable patients with narrow-complex reentry/paroxysmal SVT, arrhythmias of supraventricular origin, and for acute ventricular rate control in patients with atrial fibrillation
  • IV doses are recommended for hemodynamically stable patients with focal atrial tachycardia, AVNRT and may be used in patients with acute junctional tachycardia
  • IV Verapamil is recommended for patients with left ventricular fascicular ventricular tachycardia
  • Delay conduction and increase refractoriness in the AV node
  • Avoid use in patients with left ventricular (LV) systolic dysfunction, pre-excited atrial fibrillation, and decompensated heart failure

Vernakalant

  • Inhibits both atrial sodium and potassium repolarising currents; classified as both antiarrhythmic agent class I and III
  • IV doses may be used for pharmacological cardioversion in hemodynamically stable recent-onset atrial fibrillation patients with 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 with vagal maneuver and display flutter waves
  • Vagal maneuvers (or Adenosine) often will suppress AVNRT and 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 and halt of sympathetic stimulation, which leads to a decrease in sinoatrial node activity and AV node conduction

Carotid Sinus Massage

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

Lifestyle Modification

  • Avoidance of stimulants such as caffeine, alcohol, tobacco, medications (cough and cold preparations, beta-agonists), and recreational drugs (amphetamine, cocaine) may help prevent recurrence of sinus tachycardia
  • Appropriate hydration is encouraged for patients with signs of dehydration or febrile states
  • Exercise training, in addition to the above interventions, is recommended in the management of IST
  • Application of an ice pack on the face may also help relieve symptoms but further studies are needed to prove its use in tachyarrhythmias

Ablation

  • Treatment option for patients who experience treatment failure after pharmacological therapies or for patients with paroxysmal atrial fibrillation who prefer interventional treatment
  • Catheter ablation is preferred over surgical ablation because of significantly increased complications after surgical ablation
  • Patients on anticoagulant therapy should be assessed for bleeding risk prior to interruption of treatment preprocedurally
    • Interruption of anticoagulant therapy is not necessary in patients with no clinically significant or low bleeding risk and without patient-related factors that may increase bleeding risk
    • May interrupt therapy if patient has intermediate, high, or uncertain bleeding risk, and with patient-related factors that may increase bleeding risk
      • Duration of VKA therapy interruption depends on the patient's INR level
      • Duration of NOAC therapy interruption depends on the patient's bleeding risk, NOAC used, and estimated creatinine clearance
    • Establish hemostasis prior to restarting anticoagulant therapy for any invasive procedure

Catheter Ablation

  • Alternative treatment option for patients with symptomatic focal atrial tachycardia, recurrent atrial flutter, junctional tachycardia, recurrent symptomatic SVT in patients with adult congenital heart disease, paroxysmal or persistent atrial fibrillation, and short-coupled torsades de pointes
  • Recommended for patients with scar-related cardiac disease with incessant VT, or ischemic heart disease and recurrent implantable cardioverter defibrillator (ICD) shocks due to sustained ventricular tachycardia
    • May be considered in patients with ischemic heart disease and ICD after first episode of sustained ventricular tachycardia
  • Recommended first-line treatment for patients with symptomatic AVNRT with ongoing treatments using the slow-pathway technique
  • May be an option for rhytm control in patients with symptomatic paroxysmal or persistent atrial fibrillation unresponsive or intolerant to ≥1 class I or class III antiarrhythmic agents
  • Patients with chronic AVNRT, AVRT, pre-excitation atrial fibrillation, and patients with WPW syndrome may benefit from catheter ablation of the accessory pathway
  • May be used for patients with atrial flutter involving the cavotricuspid isthmus (CTI) who are symptomatic or unresponsive to pharmacological therapies, and non-CTI dependent atrial flutter with treatment failure after treatment with at least 1 antiarrhythmic agent
  • Treatment option for patients with VT and unresponsive or intolerant to antiarrhythmic agents or refused antiarrhythmic agents

Surgical Ablation

  • May be considered in patients with severe cases of inappropriate sinus tachycardia, ventricular tachycardia, paroxysmal or persistent atrial fibrillation refractory or intolerant to Class I or III antiarrhythmic agents and in atrial fibrillation/atrial flutter patients with adult congenital heart disease undergoing scheduled surgical repair
  • May be done during cardiac surgery in patients with persistent ventricular tachycardia/flutter even after catheter ablation

Radiofrequency Ablation

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

Atrioventricular (AV) Node Ablation and Pacemaker Implantation

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

Implantable Cardioverter Defibrillator (ICD)

  • Recommended in patients with documented ventricular fibrillation or hemodynamically unstable ventricular tachycardia
  • May be considered in patients with recurrent sustained ventricular tachycardia >48 hours after MI
    • Reduces the risk of sudden cardiac death in patients with symptomatic heart failure, left ventricular dysfunction, and heart transplant candidates
  • Implantation may be commenced subcutaneously or via transvenous route
  • External defibrillators (wearable cardioverter defibrillators) should be considered in patients with 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 with an implantable cardiac device
  • May be considered in patients with focal atrial tachycardia and recurrent atrial tachycardia, refractory ventricular tachycardia with enhanced automaticity, Digoxin-induced tachycardia, and 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 and catheter ablation
    • Produces better prognosis compared to treatment with antiarrhythmic agents
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