Supraventricular Tachycardia

Cardiology

Clinicals - History

Fact Explanation
Awareness of the rapid heart rate which is of abrupt onset and cessation Supraventricular tachycardias (SVTs) involve components of the conduction system within or above the bundle of His . Re-entry using an accessory pathway is the most common mechanism of SVT in infants. Some mechanisms of SVT are associated with congenital heart disease; however most children with SVT have structurally normal hearts. Awareness of the rapid heart rate which is of abrupt onset and cessation
Supraventricular tachycardias (SVTs) involve components of the conduction system within or above the bundle of His . Re-entry using an accessory pathway is the most common mechanism of SVT in infants. Some mechanisms of SVT are associated with congenital heart disease; however most children with SVT have structurally normal hearts.
Precordial discomfort and heart failure When the heart rate is exceptionally rapid or if the attack is prolonged only. Precordial discomfort and heart failure
When the heart rate is exceptionally rapid or if the attack is prolonged only.
Sudden death AV re-entrant tachycardia uses a bypass tract that may either be able to conduct antegrade (Wolff-Parkinson-White [WPW] syndrome. If the accessory pathway rapidly conducts in antegrade fashion, the patient is at risk for atrial fibrillation begetting ventricular fibrillation, consequent sudden death. Sudden death
AV re-entrant tachycardia uses a bypass tract that may either be able to conduct antegrade (Wolff-Parkinson-White [WPW] syndrome. If the accessory pathway rapidly conducts in antegrade fashion, the patient is at risk for atrial fibrillation begetting ventricular fibrillation, consequent sudden death.
Exercise induced syncope Due to cardiac rhythm disturbance. Exercise induced syncope
Due to cardiac rhythm disturbance.

Clinicals - Examination

Fact Explanation
Tachycardia (>180 beats per minute) Heart rate in SVT tends to be unvarying, whereas in sinus tachycardia the heart rate varies with changes in vagal and sympathetic tone. Supraventricular tachycardias (SVTs) involve components of the conduction system within or above the bundle of His . Re-entry using an accessory pathway is the most common mechanism of SVT in infants. Some mechanisms of SVT are associated with congenital heart disease; however most children with SVT have structurally normal hearts. Tachycardia (>180 beats per minute)
Heart rate in SVT tends to be unvarying, whereas in sinus tachycardia the heart rate varies with changes in vagal and sympathetic tone. Supraventricular tachycardias (SVTs) involve components of the conduction system within or above the bundle of His . Re-entry using an accessory pathway is the most common mechanism of SVT in infants. Some mechanisms of SVT are associated with congenital heart disease; however most children with SVT have structurally normal hearts.
Symptoms of heart failure in infants such as cyanosis , restlessness/irritability, tachypnoea, hepatomegaly. Heart rate at this age is normally rapid and, even in the absence of tachyarrhythmia, it increases greatly with crying. Infants with SVT are often initially seen in heart failure because the tachycardia goes unrecognized for a long time. Symptoms of heart failure in infants such as cyanosis , restlessness/irritability, tachypnoea, hepatomegaly.
Heart rate at this age is normally rapid and, even in the absence of tachyarrhythmia, it increases greatly with crying. Infants with SVT are often initially seen in heart failure because the tachycardia goes unrecognized for a long time.

Investigations - Diagnosis

Fact Explanation
Electrocardiogram In neonates, SVT is usually manifested as a narrow QRS complex (<0.08 sec). The P wave is visible on a standard electrocardiogram in only 50–60% of neonates with SVT, but it is detectable with a transesophageal lead in most patients. Electrocardiogram
In neonates, SVT is usually manifested as a narrow QRS complex (<0.08 sec). The P wave is visible on a standard electrocardiogram in only 50–60% of neonates with SVT, but it is detectable with a transesophageal lead in most patients.
Twenty-four hour electrocardiographic (Holter) recordings It is useful in monitoring the course of therapy and in detecting brief runs of asymptomatic tachycardia Twenty-four hour electrocardiographic (Holter) recordings
It is useful in monitoring the course of therapy and in detecting brief runs of asymptomatic tachycardia
Transesophageal pacing A brief assessment of arrhythmia control can be made at the bedside using this Transesophageal pacing
A brief assessment of arrhythmia control can be made at the bedside using this
Electrophysiologic study Multiple electrode catheters are placed in different locations in the heart and can aid in pinpointing an ectopic focus or bypass tract. Electrophysiologic study
Multiple electrode catheters are placed in different locations in the heart and can aid in pinpointing an ectopic focus or bypass tract.
Graded exercise testing This could be udes as an ideal noninvasive provocative test for SVT induction in suspected cases Graded exercise testing
This could be udes as an ideal noninvasive provocative test for SVT induction in suspected cases
An implantable loop recorder Implantable loop recorders can play an important role in the diagnosis of life-threatening arrhythmias in children whose syncope is otherwise unexplained. An implantable loop recorder
Implantable loop recorders can play an important role in the diagnosis of life-threatening arrhythmias in children whose syncope is otherwise unexplained.
Echocardiography To identify any structural heart disease Echocardiography
To identify any structural heart disease

Investigations - Management

Fact Explanation
Twenty-four hour electrocardiographic (Holter) recordings These are useful in monitoring the course of therapy and in detecting brief runs of asymptomatic tachycardia Twenty-four hour electrocardiographic (Holter) recordings
These are useful in monitoring the course of therapy and in detecting brief runs of asymptomatic tachycardia
Transesophageal pacing A brief assessment of arrhythmia control can be made at the bedside Transesophageal pacing
A brief assessment of arrhythmia control can be made at the bedside
Echocardiography To identfy any sign of heart failure Echocardiography
To identfy any sign of heart failure
Echocardiography To identify any structural heart disease Echocardiography
To identify any structural heart disease
Twenty-four hour electrocardiographic (Holter) recordings As prerequisites to radiofrequency ablation Twenty-four hour electrocardiographic (Holter) recordings
As prerequisites to radiofrequency ablation
Transesophageal pacing As prerequisites to radiofrequency ablation Transesophageal pacing
As prerequisites to radiofrequency ablation
Electrophysiologic study As prerequisites to radiofrequency ablation Electrophysiologic study
As prerequisites to radiofrequency ablation

Management - Supportive

Fact Explanation
Circulatory and respiratory support (positive pressure ventilation if required) For the correction of tissue acidosis Circulatory and respiratory support (positive pressure ventilation if required)
For the correction of tissue acidosis
Vagal stimulating manoeuvres Following maneuvers can be attempted: submersion of the face in iced saline (in older children) , placing an ice bag over the face (in infants) ,carotid sinus massage, in order to abolish the paroxysm, older children may be taught vagotonic maneuvers such as the Valsalva maneuver, straining, breath holding, drinking ice water, or adopting a particular posture. Vagal stimulating manoeuvres
Following maneuvers can be attempted: submersion of the face in iced saline (in older children) , placing an ice bag over the face (in infants) ,carotid sinus massage, in order to abolish the paroxysm, older children may be taught vagotonic maneuvers such as the Valsalva maneuver, straining, breath holding, drinking ice water, or adopting a particular posture.
Intravenous Adenosine This is the treatment of choice. It terminates tachycarida by breaking the re entry circuit that is set up between the atrioventricular node and the accessory pathway Intravenous Adenosine
This is the treatment of choice. It terminates tachycarida by breaking the re entry circuit that is set up between the atrioventricular node and the accessory pathway
Electrical cardioversion with a synchronized DC shock (0.5-2 J/kg) In urgent situations when symptoms of severe heart failure have already occurred Electrical cardioversion with a synchronized DC shock (0.5-2 J/kg)
In urgent situations when symptoms of severe heart failure have already occurred

Management - Specific

Fact Explanation
Pharmacological management with Anti Arrhythmic agents digoxin or propranolol, procainamide, quinidine, flecainide, propafenone, sotalol can be used to convert into sinus rhythm. In children with evidence of pre-excitation (WPW syndrome), digoxin or calcium channel blockers may increase the rate of anterograde conduction of impulses through the bypass tract and should be avoided. These patients are usually managed in the long term with propranolol Pharmacological management with Anti Arrhythmic agents
digoxin or propranolol, procainamide, quinidine, flecainide, propafenone, sotalol can be used to convert into sinus rhythm. In children with evidence of pre-excitation (WPW syndrome), digoxin or calcium channel blockers may increase the rate of anterograde conduction of impulses through the bypass tract and should be avoided. These patients are usually managed in the long term with propranolol
Radiofrequency ablation or cryoablation of the accessory pathway. , , For ablation of the accessory pathway. It is often used electively in children and teenagers, as well as in patients who require multiple agents or find drug side effects intolerable or for whom arrhythmia control is poor. The overall initial success rate ranges from approximately 80% to 95%, depending on the location of the bypass tract or tracts Radiofrequency ablation or cryoablation of the accessory pathway. , ,
For ablation of the accessory pathway. It is often used electively in children and teenagers, as well as in patients who require multiple agents or find drug side effects intolerable or for whom arrhythmia control is poor. The overall initial success rate ranges from approximately 80% to 95%, depending on the location of the bypass tract or tracts
Surgical ablation For ablation of the accessory pathway in selected patients Surgical ablation
For ablation of the accessory pathway in selected patients

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