Supraventricular tachycardia Rate usually >220 beats/min (range, 180–320 beats/min); Increase vagal tone (bag of ice water to face, abnormal atrial rate for age; P waves may be present Valsalva maneuver); adenosine; digoxin; and are related to QRS complex; normal, narrow QRS sotalol; electrical cardioversion if acutely ill; complexes unless aberrant conduction is present catheter ablation
Atrial flutter Atrial rate usually 300 beats/min, with varying degrees of Digoxin, sotalol, cardioversion block; sawtooth flutter waves
Ventricular fibrillation No distinct QRS complex or T waves; irregular Nonsynchronized cardioversion undulations with varied amplitude and contour, no conducted pulse
First-degree heart block Prolonged PR interval for age Observe, obtain digoxin level if on therapy
Mobitz type I (Wenckebach) Progressive lengthening of PR interval until P wave is not Observe, correct underlying electrolyte or second-degree heart block followed by conducted QRS complex other abnormalities
Mobitz type II second-degree Sudden nonconduction of P wave with loss of QRS Consider pacemaker heart block complex without progressive PR interval lengthening
Sinus tachycardia Rate <240 beats/min Treat cause (fever), remove sympathomimetic drugs
AV, Atrioventricular; ECG, electrocardiogram.
Ia Prolongation of QRS complex and QT interval Quinidine, procainamide, disopyramide
Ib Significant effect on abnormal conduction Lidocaine, mexiletine, phenytoin, tocainide
Ic Prolongation of QRS complex and PR interval Flecainide, propafenone, moricizine?
β blockade; slowing of sinus rate; prolongation of PR interval Propranolol, atenolol, acebutolol
Prolongation of action potential; prolongation of PR, QT intervals, QRS Bretylium, amiodarone, sotalol complex; sodium and calcium channel blockade
Calcium channel blockade; reduction in sinus and AV node pacemaker activity Verapamil and other calcium channel blocking and conduction; prolongation of PR interval agents
AV, Atrioventricular.
Most atrial dysrhythmias require no intervention. Treatment of SVT depends on presentation and symptoms.Acute treatment of SVT in infants usually consists of vagal maneuvers, such as application of cold (ice bag) to the face.Intravenous (IV) adenosine usually converts the dysrhythmia because the atrioventricular node forms a part of thereentry circuit in most patients with SVT. In patients withcardiovascular compromise at the time of presentation, synchronized cardioversion is indicated using 1 to 2 J/kg. Inpatients with palpitations, it is important to document heartrate and rhythm during their symptoms before consideringtherapeutic options. The frequency, length, and associatedsymptoms during the episodes, as well as what is required to convert the rhythm, determine the need for treatment.Some patients require only education regarding the dysrhythmia and follow-up. Ongoing pharmacologic management with either digoxin or a β-blocker is usually the firstchoice. However, digoxin is contraindicated in patientswith Wolff-Parkinson-White syndrome. Additional antiarrhythmic medications are rarely needed. In patients who aresymptomatic or those not wanting to take daily medications,radiofrequency ablation may be performed.
A variety of antiarrhythmic agents are used to treat ventricular dysrhythmias that require intervention (Table 142-3).Management of third-degree heart block depends on the ventricular rate and presence of symptoms. Treatment, if needed, often requires placement of a pacemaker.
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