supraventricular tachycardia (svt) - usu ocw.usu.ac.id/.../emd166_slide_supraventricular_...

Supraventricular Tachycardia (SVT)Supraventricular Tachycardia (SVT)Supraventricular Tachycardia (SVT)Supraventricular Tachycardia (SVT)

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Supraventricular Tachycardia (SVT)Supraventricular Tachycardia (SVT)Supraventricular Tachycardia (SVT)Supraventricular Tachycardia (SVT)

SVT is characterized by rapid heart rates, usually 200 to

300 beats/minute, with a QRS complex of normal

duration

Cardiovascular emergency in infant and children

The incidence: 1/25,000-1/250

Early detection and prompt treatment important

Congestive heart failure

Circulatory arrest

Mechanism of SVT

Mechanism of SVT

Automaticity Automaticity

Reentry

Mechanism of SVT

Automaticity Acceleration of phase 4 Source:

Atrium AV junction His bundle Ventricle Pulmonary vein SVC

Cause Metabolic disorder Hypoxia Hypokalemia Hypo magnesemia acidosis

Mechanism of SVT

Reentry

Condition

Two pathway make closed closed circuit

Block in 1 pathway

Antegrad in normal conductionretrograd in block pathway

Mechanism of SVT

The episodes usually start and end abruptly

Wolff-Parkinson-White (WPW) syndrome is

responsible for about 50% of SVT in neonates

Structural heart diseases (such as Ebstein's Structural heart diseases (such as Ebstein's

Anomaly, Tricuspid Atresia, and cardiac tumors)

are less frequent causes of SVT in neonates

Viral myocarditis and thyrotoxicosis also have

been associated with SVT

Short episodes of tachycardia usually do not harm the patient

Newborns with sustained SVT become restless and Newborns with sustained SVT become restless and

tachypneic with feeding difficulties and eventually develop

signs of CHF and circulatory shock within 12 to 24 hours

after onset

Although rare, SVT diagnosed in utero may present with

severe CHF at birth and has a high mortality rate, requiring

prenatal treatment

TreatmentTreatmentTreatmentTreatment

Adenosine is the treatment of choice, followed by digitalization

Adenosine is given in a rapid intravenous bolus, starting at 50 g/kg, every 1 to 2 minutes (maximum, 250 g/kg)

If the patient is unresponsive to adenosine and is in CHF, cardioversion may be performed, followed by digitalization and diuretics

In SVT of short duration without signs of CHF, digoxin alone is used

An ice bag applied to the face has been effective in some neonates

Vagal stimulatory maneuvers rarely are effective in neonates

Transesophageal atrial overdrive stimulation may prove effective

Verapamil and propranolol are not the drugs of choice

Verapamil and propranolol are not the drugs of choice

Tried only when other measures fail, and may produce extreme bradycardia and hypotension in a newborn; one should administer these drugs in a step-by-step dosage, monitor the infant carefully, and be prepared to resuscitate

Short-Term management

of SVT

Delacretaz. NEJM 2006;354:1039-51

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