Each type causes the abnormal fast heart rate in a slightly different way. Treatment depends on the type of SVT and what is causing it, if known. Treatment might include medicines that slow the heart rate or a procedure called catheter ablation that stops the rhythm problem. Atrial fibrillation is a common heart rhythm problem. The heart's upper chambers atria beat irregularly. But it is not commonly considered a type of SVT. Atrial flutter is like atrial fibrillation, because the electrical problem is in the atria.
But with atrial flutter, the heart beats very fast in a regular rhythm. It accounts for many of the fast heart rates that start in the upper part of the heart excluding atrial fibrillation. Atrioventricular AV nodal reentrant tachycardia can cause symptoms at any age. It typically is not a result of other forms of heart disease. AVNRT is caused by an abnormal or extra electrical pathway in the heart, a kind of "short circuit.
Normally, a single electrical pathway allows impulses to travel from the upper to the lower chambers. An extra electrical pathway in the AV node allows those impulses to travel backward at the same time, starting another heartbeat.
This is known as "reentry" and can lead to a very fast heart rate. Atrioventricular reciprocating tachycardia AVRT occurs when there is an extra electrical pathway linking the upper atria and lower ventricles chambers of the heart. Normally, the AV node is the only tissue that conducts electrical impulses between the upper and lower chambers of the heart. All electrical impulses must go through the AV node to reach the lower chambers of the heart. In an atrioventricular reciprocating tachycardia, electrical impulses travel one direction in the normal manner, down the AV node to the lower chambers ventricles , but they then travel back up to the upper chambers atria through an abnormal, extra electrical pathway accessory pathway located outside the AV node.
Atrial tachycardia is a type of fast heart rate caused by rapid electrical signals that begin in the upper chambers of the heart. Table 4 lists items to include in a focused examination and diagnostic workup. Possible atrioventricular nodal reentrant tachycardia or ventricular tachycardia. A lead ECG should be performed in patients who are hemodynamically stable, with special attention to rhythm and rate, atrioventricular conduction PR interval , RP interval, hypertrophy, pathologic Q waves, prolongation of the QT interval, and any evidence of preexcitation.
Wide complex tachyarrhythmias can also occur and can be secondary to SVT associated with bundle branch block, an accessory pathway, or ventricular tachycardia. In patients with a history of or suspected coronary artery disease or myocardial infarction, wide complex tachyarrhythmias must be considered to be of ventricular origin until proven otherwise and treated as such see the treatment section.
Electrocardiogram of a narrow complex tachycardia with a atrioventricular association in a yearold girl with tachypalpitations. The differential diagnosis includes atrial tachycardia, atrioventricular nodal reentrant tachycardia, and orthodromic atrioventricular reciprocating tachycardia.
Rhythm was terminated with 6 mg of intravenous adenosine Adenocard. Postconversion electrocardiogram demonstrating the typical features of ventricular preexcitation with short PR interval and prominent delta wave. This finding supports orthodromic atrioventricular entry as the likely mechanism of supraventricular tachycardia.
Diagnostic electrophysiology confirmed the mechanism. Electrocardiogram of a narrow complex tachycardia with a atrioventricular association. This example represents atrioventricular reciprocating tachycardia, which has a high cure rate with catheter ablation therapy.
Electrocardiogram of a narrow complex tachycardia with atrioventricular association and right bundle branch block aberration. This example represents atrioventricular nodal reentrant tachycardia, which is also depicted in Figure 1A. Further clinical investigations and their possible significance to SVT should be pursued Table 4. Patients should be expediently referred to a cardiologist or electrophysiologist if they have experienced syncope or severe dyspnea, or if preexcitation is present on resting lead ECG.
Table 5 lists other situations in which patients should be referred to a cardiologist or electrophysiologist. Patient has worsening symptoms or is becoming hemodynamically unstable Patient is in a high-risk occupation e. Physician is uncomfortable with or uncertain about management or initial diagnosis. Preexcitation is present on electrocardiography or if atrioventricular reciprocating tachycardia is suspected. The primary treatment goal for any SVT is its cessation, especially in patients who are at risk hemodynamically and cannot tolerate prolonged tachyarrhythmias.
SVT may be rare and fleeting in some patients, whereas in others, it is more frequent and may cause serious symptoms such as presyncope or syncope. Treatment of SVT can be divided into short-term or urgent management and long-term management.
Short-term or urgent management of SVT can be separated into pharmacologic and nonpharmacologic strategies. Nonpharmacologic management typically uses maneuvers that increase vagal tone to decrease heart rate.
Pharmacologic management typically includes intravenous adenosine Adenocard or verapamil, which are safe and effective treatment choices for terminating SVT, but verapamil is more effective for suppression of this rhythm over time.
Algorithm of the short-term management of supraventricular tachycardia SVT. Clinical practice. Supraventricular tachycardia. N Engl J Med. If the patient is hemodynamically stable, the QRS complex can provide information in decision making. A narrow QRS complex less than msec usually indicates SVT, and the Valsalva maneuver is the most widely used and feasible treatment option in an alert patient.
Although the use of this technique has been accepted in hospitalized settings, it has not been studied in the prehospital setting to determine its effectiveness. Table 6 shows recommended agents for short-term management of SVT. Avoid in patients with Wolff-Parkinson-White syndrome or wide complex tachycardia. Avoid in patients with congestive heart failure, Wolff-Parkinson-White syndrome, wide complex tachycardia, or atrioventricular block second or third degree.
Information from reference Adenosine is an atrioventricular nodal blocking agent with a very short half-life nine to 12 seconds. It is highly effective for the termination of nodal-dependent SVT and is the first-line drug for acute conversion of narrow complex SVT. Adenosine should not be used in persons with Wolff-Parkinson-White syndrome and atrial fibrillation because this rhythm can degenerate into ventricular fibrillation.
Verapamil is a calcium channel blocker that may be used in patients with SVT that recurs after adenosine therapy. Verapamil, a negative inotrope, can result in relative bradycardia and vasodilation; care must be used if patients have a significant decrease in cardiac output.
In a review of eight trials involving patients, there was no difference in the effectiveness of adenosine versus verapamil in successfully treating SVT. The overall termination rate was about 90 percent for both agents. Compared with narrow complex tachycardia, wide complex tachycardia presents infrequently, but does occur under certain conditions. Wide complex tachycardia is often difficult to distinguish from ventricular tachycardia, and all types should be treated as ventricular tachycardia when SVT cannot be discerned, particularly in patients who are hemodynamically unstable.
If the patient is hemodynamically stable, use of the wellknown Brugada criteria Table 7 can help distinguish between SVT with aberrancy and ventricular tachycardia, with a reported sensitivity as high as It may be more accurate in determining true ventricular tachycardia, with a reported overall test accuracy of Supraventricular tachycardia with aberrant conduction is diagnosis made by exclusion. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex.
A recent retrospective study showed that intravenous adenosine used in patients with undifferentiated wide complex tachycardia was safe and effective for diagnostic and therapeutic purposes.
No adverse effects occurred, and the likelihood of making a correct diagnosis of SVT or ventricular tachycardia increased. The long-term management of SVT is based on the SVT type; frequency and intensity of the episodes; overall impact on the quality of life of the patient; and risks of the therapy chosen.
The primary options include catheter ablation radiofrequency versus cryotherapy or pharmacologic treatment Table 6. Algorithm of the long-term management of supraventricular tachycardia SVT. This is typically done with verapamil 40 to mg in patients without preexcitation or a beta blocker in patients without chronic obstructive pulmonary disease or asthma.
Agents used for long-term pharmacotherapy are similar to those used to terminate the SVT during short-term management. Atrioventricular nodal blocking agents e.
Larger trials comparing outcomes between these drug classes are not yet available Table 8 Generally, these agents should be managed by a cardiologist. Kinetics of onset and offset in blocking the sodium channel are of intermediate rapidity less than five seconds.
Kinetics of onset and offset in blocking the sodium channel are rapid less than msec. Kinetics of onset and offset in blocking the sodium channel are slow 10 to 20 seconds. Predominantly block potassium channels e. Examples include verapamil, diltiazem, nifedipine Procardia , felodipine blocks T-type calcium channel.
Ablative therapy of SVT is based on the observation that most arrhythmias arise from a focal origin critically dependent on conduction through a defined anatomic structure.
If those critical regions are destroyed, the arrhythmia no longer occurs spontaneously or with provocation. Because of shorter procedure duration, lessened fluoroscopic exposure, and increased knowledge in this area of cardiology, catheter ablation is becoming the first-line treatment option for all patients with SVT, not just those with symptomatic arrhythmias refractory to suppressive drug therapy or those who prefer a drug-free lifestyle.
Clinical series of radiofrequency catheter ablation of accessory pathways have been published with excellent overall results. Because of its curative results and low percentages of severe adverse effects, and because the field is evolving so rapidly, there are few studies directly comparing catheter ablation with drug therapy in patients with SVT with the exception of atrial fibrillation.
However, observational studies have reported that patients undergoing radiofrequency ablation for SVT have better overall quality-of-life outcomes and lower costs attributed to therapy compared with medical treatment. Already a member or subscriber? Log in. Interested in AAFP membership?
Learn more. Address correspondence to Randall A. Reprints are not available from the authors. J Am Coll Cardiol. The lead electrocardiogram in supraventricular tachycardia Cardiol Clin. Influence of age and gender on the mechanism of supraventricular tachycardia. Heart Rhythm. Supraventricular tachycardia mechanisms and their age distribution in pediatric patients.
Am J Cardiol. Wellens HJ, Brugada P. Mechanisms of supraventricular tachycardia. Paroxysmal supraventricular tachycardia in the general population. Sometimes episodes stay relatively the same or get worse. And sometimes they fade entirely. My episodes worsened before they let up. To help, my doctor told me there were certain things I could do—like splashing my face with icy water or doing a headstand—that might help return my heartbeat to normal.
These techniques are called vagal maneuvers, because they stimulate the vagus nerve, which runs from the brain all the way down to the colon. Other vagal maneuvers include coughing, gagging and holding your breath and bearing down.
Not all maneuvers work for everyone. Cold water never worked for me, but headstands did. For people whose episodes are debilitating enough to interfere with everyday life, there are solutions more lasting than vagal maneuvers.
Medications designed to suppress the electrical short circuiting could be helpful for some people, Akoum says. If a permanent fix is needed, a catheter ablation could be the solution. Akoum performs this procedure regularly. Digitoxin is a suitable alternative to digoxin, where available. In the setting of heart failure or hypotension, digitalis 0. In pre-excitation, only class I drugs or amiodarone are safe. AF with slow ventricular rates may respond to atropine 0.
Exacerbations of SVT p. Adenosine and electrical cardioversion are not contraindicated see Table Digoxin is safe, but of limited value. AF is rare during pregnancy in women without previously detected AF and without a pre-existing heart disease [ 8 , 12 ].
AF during pregnancy is well tolerated in most patients without a congenital or valvular disease, but more p. Synchronized cardioversion for haemodynamically unstable SVT when other pharmacological therapies are ineffective or contraindicated. IV amiodarone for potentially life-threatening SVT when other therapies are ineffective or contraindicated.
Several case reports have demonstrated successful cardioversion of maternal AF, without harm to the fetus see Table Energy requirements in pregnant and non-pregnant women are similar.
Digoxin, a beta blocker, or a non-dihydropyridine calcium channel antagonist to control the rate of ventricular response. Direct-current cardioversion in pregnant patients who become haemodynamically unstable due to AF.
Therapy anticoagulant or aspirin should be chosen according to the stage of pregnancy. Heparin during the first trimester and last month of pregnancy for patients with AF and risk factors for thromboembolism.
Oral anticoagulant during the second trimester for pregnant patients with AF at high thromboembolic risk. Quinidine or procainamide to achieve pharmacological cardioversion in haemodynamically stable patients who develop AF. No association with low weight for gestational age has been found for labetalol started after the 6th week of gestation , as opposed to atenolol.
Digoxin crosses the placenta freely, and digitalis intoxication in the mother has been associated with fetal death. Oral verapamil and diltiazem are most probably safe see Table Sotalol, flecainide, or propafenone are second-choice drugs. IV ibutilide or flecainide are usually effective and may be considered, although the experience during pregnancy is limited [ 43 , 45 ]. All drugs should, if possible, be avoided during the period of organogenesis in the first trimester of pregnancy.
Warfarin may be used in the second trimester, with an only slightly elevated teratogenic risk. Warfarin crosses the placenta freely, and the fetus may be overdosed, even when the mother is in the therapeutic INR range.
LMWH does not cross the placenta barrier and has been used for the treatment and prophylaxis of venous thromboembolism VTE during pregnancy, without adverse fetal effects. The new oral thrombin antagonists, such as dabigatran, have shown fetotoxicity with high doses and should not be used.
The term supraventricular tachycardia SVT refers to atrial arrhythmias, including AF, atrioventricular nodal re-entry, and atrioventricular re-entry due to accessory pathway s.
In clinical practice, SVT may present as narrow or wide QRS tachycardias, and, with the potential exception of AF, most of them are usually, although not invariably, manifest as regular rhythms. They are usually intrusive, symptomatic, and anxiety-provoking, but not dangerous. In the acute setting, consideration of epidemiology data, clinical presentation, and the lead ECG can provide diagnostic clues for the differential diagnosis between SVT and ventricular arrhythmias and guide appropriate therapy.
Find this resource:. Clinical cardiology: current practice guidelines. Oxford: Oxford University Press, 2nd edn; Zipes DP, Jalife J. Cardiac electrophysiology: from cell to bedside. Philadelphia: Saunders; Clinical cardiology. Current practice guidelines. Oxford University Press. Paroxysmal supraventricular tachycardia in the general population. Influence of age and gender on the mechanism of supraventricular tachycardia. Incidence and predictors of atrial flutter in the general population.
Incidence and prevalence of atrial fibrillation: An analysis based on 8. Prevalence of atrial fibrillation in the general population and in high-risk groups: The echoes study. Secular trends in incidence of atrial fibrillation in olmsted county, minnesota, to , and implications on the projections for future prevalence. Projections on the number of individuals with atrial fibrillation in the european union, from to Eur heart j. Syncope associated with supraventricular tachycardia. An expression of tachycardia rate or vasomotor response?
Frequency of disabling symptoms in supraventricular tachycardia. Am J Cardiol. Ascending aorta doppler echocardiography in the diagnosis of broad complex tachycardia. Am Heart J. A new electrocardiographic algorithm using retrograde p. Egc diagnosis of paroxysmal supraventricular tachycardias in patients without preexcitation. Ann Noninvasive Electrocardiol. Differentiation of ventricular tachycardia from supraventricular tachycardia with aberration: Value of the clinical history.
Ann Emerg Med. A new approach to the differential diagnosis of a regular tachycardia with a wide qrs complex. Electrocardiographic criteria for ventricular tachycardia in wide complex left bundle branch block morphology tachycardias.
R-wave peak time at dii: A new criterion for differentiating between wide complex qrs tachycardias. New algorithm using only lead avr for differential diagnosis of wide qrs complex tachycardia.
Evaluation of the specificity of morphological electrocardiographic criteria for the differential diagnosis of wide qrs complex tachycardia in patients with intraventricular conduction defects. Comparison of five electrocardiographic methods for differentiation of wide qrs-complex tachycardias. Postural modification to the standard valsalva manoeuvre for emergency treatment of supraventricular tachycardias revert : A randomised controlled trial.
Adenosine in the diagnosis of broad complex tachycardias. Lancet ; 1: —75 Find this resource:. Atrioventricular nodal reentrant tachycardia. Classification of electrophysiological types of atrioventricular nodal re-entrant tachycardia: A reappraisal.. Efficacy and safety of out-of-hospital self-administered single-dose oral drug treatment in the management of infrequent, well-tolerated paroxysmal supraventricular tachycardia.
Role of invasive electrophysiologic testing in the evaluation and management of adult patients with focal junctional tachycardia. Card Electrophysiol Rev. Wren C. Incessant tachycardias. Anterior-posterior versus anterior-lateral electrode positions for external cardioversion of atrial fibrillation: A randomised trial. Vernakalant-facilitated electrical cardioversion: Comparison of intravenous vernakalant and amiodarone for drug-enhanced electrical cardioversion of atrial fibrillation after failed electrical cardioversion.
N Engl J Med. Murray KT. Acute beta-adrenoceptor blockade improves efficacy of ibutilide in conversion of atrial fibrillation with a rapid ventricular rate. Safety of oral dofetilide for rhythm control of atrial fibrillation and atrial flutter. Circ Arrhythm Electrophysiol. A randomized active-controlled study comparing the efficacy and safety of vernakalant to amiodarone in recent-onset atrial fibrillation.
Anticoagulation for cardioversion of acute onset atrial fibrillation: time to revise guidelines? Diltiazem vs. Metoprolol in the management of atrial fibrillation or flutter withrapid ventricular rate in the emergency department. J Emerg Med. Risks and benefits of beta-receptor blockers for pregnancy hypertension: Overview of the randomized trials. Ibutilide-induced cardioversion of atrial fibrillation during pregnancy.
J Cardiovasc Electrophysiol. All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Medicine Online for personal use for details see Privacy Policy and Legal Notice.
Oxford Medicine Online. Publications Pages Publications Pages.
0コメント