Supraventricular Arrhythmias by Christine LaGrasta.
Welcome to today's module on arrhythmias.
My name is Christine LaGrasta.
I work at Children's Hospital of Boston as a Pediatric Nurse Practitioner.
So we'll first start with rhythms originating in the sinus node.
These are normal sinus rhythm, sinus tachycardia, and sinus bradycardia.
Characteristics of all sinus rhythms are: there's a P wave preceding each QRS complex,
there's a regular PR interval, and the P wave is upright in lead II.
Normal sinus rhythm is the normal rhythm for any age.
The average heart rate for infants is 90 to 160 beats per minute, and for children and
teenagers it is 65 to 100 beats per minute.
Heart rates of pediatric patients vary with age.
Because of age-related changes, the simple definitions of normal heart rate, tachycardia,
and bradycardia used in the adult population are not applicable to the pediatric population.
It is always good practice to know the age and cardiac history of your patients.
Sinus tachycardia is a sinus rhythm where the heart rate is faster than the normal range
for that age group.
Causes can include anxiety, pain, dehydration, fever, myocarditis, congestive heart failure,
hypovolemia, hypotension, hypoxia, infection, anemia, and medications such as Dopamine,
Epinephrine, and Nebulized Albuterol.
Treatment involves treating the underlying cause, for example, give pain medication to
a post-operative child who is in pain and is crying.
Sinus bradycardia is a sinus rhythm where the heart rate is slower than the normal range
for that age group.
Causes include any surgical manipulation of the atria, such as the atrial septal defect
or atrial ventricular canal repairs, hypothermia, hypoxia, hyperkalemia, trained athletes, and
medications such as digitalis and beta blockers.
Treatment generally is to treat the underlying cause of bradycardia.
It is important to know the side effects of medications and to know the surgical procedures
of your patient.
Any time there is surgical work directly on the heart, changes in the conduction system
can occur.
If there is cardiopulmonary compromise, start cardiopulmonary resuscitation and follow the
Pediatric Advanced Life Support guidelines, or the PALS guidelines outlined by the American
Heart Association.
Point of clarification.
According to the PALS algorithm, Epinephrine and Atropine are also treatments for bradycardias.
The pediatric dose for Epinephrine is 0.01 milligram per kilogram of 1 to 10,000 solution
IV or IO.
Repeat every three to five minutes.
For Atropine given IV or IO, the proper dose is 0.02 milligrams per kilogram and may double
amount for second dose.
Child max is 1.0 milligram and the adolescent max is 2.0 milligrams.
Caution: Do not give less than 0.1 milligrams or may worsen the bradycardia.
The rhythms originating in the atrium other than the sinoatrial node are premature atrial
contraction, atrial flutter, and supraventricular tachycardia.
Characteristics of atrial arrhythmias are: the P waves are an unusual shape, there is
an abnormal number P waves for each QRS complex, the QRS complexes are of normal duration.
A premature atrial contraction occurs when a P wave comes prematurely before the next
expected normal beat.
The electrical conduction to the ventricle is normal.
The cause is usually an electrolyte imbalance such as abnormal potassium or magnesium levels
in post-operative patients, or it could be from Digitalis toxicity.
Treatment involves treating the electrolyte balance so that the levels are normal.
Also treat the Digitalis toxicity.
Atrial flutter.
Atrial flutter occurs when there is an extra conduction pathway in the right atrium, which
the electrical impulses can follow.
This leads to many P waves for one QRS complex.
The atrial rate can be up to 300 beats per minute.
The AV node is unable to respond to a rate this fast, so there is a degree of a atrial
ventricular block.
There are more P waves than QRS complexes.
Causes include dilated atria, myocarditis, any interatrial surgery such as atrial septal
defect repairs, valvular heart disease, and medications such as Digitalis.
Treatment includes synchronized cardioversion if hemodynamically unstable.
If stable, administer Procainamide or Propranalol.
Point of clarification.
The pediatric dose for Procainamide is 15 milligrams per kilogram IV administered slowly
over 30 to 60 minutes.
The general IV dose for Propranolol for all pediatric patients is 0.01 to 0.1 milligrams
per kilogram and is administered slowly.
Supraventricular tachycardia.
There is an extra pathway that the electrical impulse follows, which causes a fast heart
rate.
P waves are not visible and the QRS complexes are normal.
The rhythm starts and stops abruptly.
In infants, the heart rate can be greater than 220 beats per minute.
In children, the heart rate can be greater than 180 beats per minute.
Causes include any cardiac surgery that could cause inflammation in the atria or ventricles
or of the conduction pathway.
Treatment.
Vagal maneuvers, such as applying ice to the patient's face, can convert the rhythm to
a sinus rhythm.
Or the physician can give the patient Adenosine to convert the supraventricular tachycardia
to sinus rhythm, beta blockers to slow the heart rate, and Procainamide to convert the
rhythm to sinus rhythm.
If these interventions do not convert the rhythm to a sinus rhythm, synchronized cardioversion
is the next action.
Point of clarification.
The general dose of Adenosine is initially 0.1 milligram per kilo rapidly IV/IO with
a maximum dose of 6 milligrams.
If there is no effect from the initial dose, 0.2 milligrams per kilogram can be given rapidly
IV or IO, with a maximum dose of 12 milligrams.
The dosage for beta blockers is dependent upon the specific medication administered.
The pediatric dose for Procainamide is 15 milligrams per kilogram IV administered slowly
over 30 to 60 minutes.
Synchronized cardioversion is initially 0.5 to 1.0 joules per kilogram.
If not effective, increase dosage to 2.0 joules per kilogram.
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