Children with tLOC

Children presenting with syncope usually suffer from benign causes and about 80% constitute vasovagal or neuro cardiogenic syncope. From an etiological perspective, syncope in children can be divided into four likely causes:

1. Cardiovascular (tachydysrhythmias, bradydysrhythmias, outflow obstruction, and myocardial dysfunction)
2. Neurologic 
3. Metabolic 
4. Other Benign entities (Vasovagal - reduced venous return)

A prodrome of warmth, nausea, lightheadedness, and a visual gray-out is indicative of neurocardiogenic syncope. Routine laboratory studies are not needed in such cases.

Involuntary motor movements due to transient cerebral hypoxia may occur in syncopal events which may be reported as fits by laypersons. Syncope related myoclonus is generally seen after loss of consciousness (seizure-related movements are seen prior to the loss of consciousness), less rhythmic nature, and are of shorter duration. 

Red Flags for Pediatric Syncope:

• Onset with Exertion
• History of Cardiac Disease
• Heart Murmur on examination
• Family h/o Sudden Deaths or arrhythmias
• Associated chest pain/palpitations
• Syncope in Recumbent position
• Recurrent episodes
• Use of Cardiac medications
• No prodrome  
• Prolonged LOC

Exertion before a syncopal event increases the suspicion of structural heart disease, specifically cardiac outflow obstruction. 


Investigations

• ECG - Remember, ECG is a snapshot and some patients with an underlying arrhythmia may have normal ECG
• Selection of other laboratory tests should be guided by clinical suspicion. Blood tests are required as indicated by history. Consider performing a serum alcohol level, a urine drug screen and a beta hCG in adolescents. 
• ECHO - Done for those with known cardiac disease, abnormal heart sounds, abnormal cardiac murmurs, evidence of cardiac chamber enlargement, or repolarization abnormalities on ECG, or other features that suggest myocardial dysfunction.
• EEG -  Low diagnostic yield and not needed routinely.

A detailed history, physical exam, and ECG have a 96% sensitivity for detecting cardiac syncope.

Things to look for in ECG:

• Brady and Tachyarrythmias (AV Blocks, SVT, AF, VT)
• Brugada (IRBBB, STE V1-V3)
• QTc (Long and Short)
• WPW (triad - Wide QRS, Short PR, Delta wave)
• HOCM (High LV Voltage, dagger like q waves, TWI)
• ARVD (epsilon wave)
• Chamber Enlargement 
• Septal Defects (Crochetage Pattern for OS ASD)

Treatment

Treatment is targeted to specifically identified causes of the syncopal event; 80% of the time, this will be neurocardiogenic syncope, and treatment for these patients includes reassurance and oral fluids. Children with a normal ECG, full recovery and no cardiac risk factors or exercise-induced symptoms may be safely evaluated as outpatients.

Take Home:

• A detailed history, physical exam, and ECG have a 96% sensitivity for detecting cardiac syncope.
• There are no routine blood tests - request bloods based on history and physical.
• Know what to look for in the ECG in patients presneting with syncope.

Posted by:

              

     Lakshay Chanana

     

     Speciality Doctor

     Northwick Park Hospital

     Department of Emergency Medicine

     England

     @EMDidactic