CARDIOLOGY Flashcards
What is the differential diagnosis of prolonged QT?
- Congenital: -Romano-Ward syndrome (most common genetic cause of prolonged QT syndrome, autosomal dominent) -Jervell-Lange-Nielsen syndrome (associated with deafness) 2. Acquired -Drugs (antiarrhythmics, dexmedetomidate, TCAs, antipsychotics, antibiotics such as macrolides) -Electrolytes (hypocalcemia, hypokalemia, hypomagnesemia) -Intracranial lesion (encephalitis, head trauma, stroke) -Cardiac disease
What is the treatment for myocarditis?
SUPPORTIVE for mild cases 1. Bed rest 2. Digoxin 3. Cautious diuresis since they’re preload dependent (will need some volume) 4. Afterload reduction - ACE inhibitor 5. Anti arrhythmic For severe cases: may need inotropes/ICU support
What is the rule of 1/3s for myocarditis?
1/3 complete recover 1/3 develop chronic dilated cardiomyopathy and require lifelong failure management 1/3 require transplant or have sudden death from arrhythmia
What is the differential diagnosis for left axis deviation on ECG (5)?
Left axis deviation is always abnormal 1. AVSD 2. Tricuspid atresia 3. Pulmonary atresia 4. Pulmonary stenosis 5. Single LV
What is the cause of biventricular hypertrophy on ECG?
VSD
What 3 congenital heart diseases is most likely to present with severe cyanosis within the first few hours of life?
- Transposition of the great arteries (MOST COMMON PRESENTING CYANOTIC LESION TO PRESENT IN NEWBORN PERIOD) -only mixing is through an open PDA and PFO -need PGE1 to keep PDA open in order to maintain oxygenation to systemic circulation
- Pulmonary atresia
- Ebstein’s anomaly
What are the clinical signs and symptoms of a “tet spell” (3)? What occurs physiologically during a “tet spell”?
(aka hypercyanotic spell)
- Acute onset of intense cyanosis
- Sudden softening of murmur (due to decreased blood flow through the obstructed right outflow tract)
- Deep rapid respiratory pattern (no work of breathing should be seen theoretically)
“Tet spell” - acute, sudden onset of increased right ventricular outflow tract obstruction and resultant decreased pulmonary blood flow (can be precipitated by agitation, fever, exercise, etc) –> obstruction of deoxygenated blood flow into the pulmonary artery –> deoxygenated blood shunts through the large VSD into the left ventricle –> deoxygenated blood flows into systemic circulation causing cyanosis -typically present starting at around 2 months of age as right ventricular outflow tract obstruction worsens -indication for urgent surgical repair
What are the 4 characteristic heart defects in Tetralogy of Fallot?
- Overriding aorta (empties from both the LV and RV) 2. RVH 3. Right ventricular outflow tract obstruction (ie. pulmonary stenosis) 4. VSD
In Tetralogy of Fallot, what does the severity of clinical signs and symptoms depend on?
The degree of right ventricular outflow tract obstruction
What 3 genetic conditions can be commonly be associated with Tetrology of Fallot?
- DiGeorge syndrome (22q11 deletion)
- Down syndrome
- Alagille syndrome
What is the immediate management of a “tet spell”?
Step-wise approach: if one step fails, move onto the next
- Put patient in knee-chest position -as with squatting, knee-chest position increases systemic vascular resistance, thus increasing left ventricular pressure and decreasing the right to left shunt of deoxygenated blood, promoting flow instead back into the lungs -also increases venous return to right side of heart to promote flow to lungs
- Administer O2 -O2 is pulmonary vasodilator (decreasing pulmonary vascular resistance and thus increases blood flow to lungs) and systemic vasoconstrictor
- Administer morphine (0.1 mg/kg) and give fluid bolus -morphine theoretically decreases agitation and thus RVOT obstruction -fluids improves venous return
- Administer IV beta blocker (propanolol 0.1 mg/kg) -causes relaxation of RVOT obstruction
- Administer IV phenylephrine (selective alpha agonist) -increases afterload (systemic vascular resistance)
What is a PVC?
Premature ventricular contraction - heartbeat is initiated by Purkinje fibers in the ventricles instead of the SA node -wide QRS -ventricles contract before atria has had time to fill them with blood
What are the 4 types of PVCs?
- Bigeminy -PVC occurs after every normal beat = non concerning
- Trigeminy -two normal beats to one PVC = non concerning 3. Quadrigeminy -three normal beats to one PVC = non concerning
- Ventricular tachycardia -3 or more PVCs occuring in a row = concerning obviously
What noninvasive tests can be ordered to investigate a history of arrhythmia (4)?
- ECG
- Holter monitor
- Event recorders -loop recorders: children always wear the device and press a button when they experience symptoms -pacer tracers: connected to telephone for recording
- ECHO
What are the two treatment modalities for chronic arrhythmias?
- Medical therapy with antiarrhythmics 2. Catheter ablation therapy
When would catheter ablation be the treatment of choice for a child with a tachyarrthymia over medical therapy?
If tachyarrhythmia has caused a life-threatening event
What is the treatment of choice for children with bradyarrythmias?
Cardiac pacing
What can be seen on ECG of a patient with Wolff-Parkinson-White syndrome (2)?
- Delta waves - short PR interval with upsloping, reflects pre-excitation (electrical conduction from atria to ventricle via pathway other than AV node) since the normal delay between the P and the R is missing (ie. the normal delay of electrical conduction by the AV node)
- Wide QRS
What are the 2 types of SVT (and 2 subtypes within each type)?
1. Re-entry
a) AVRT (atrioventricular reentrant tachycardia)
b) AVNRT (atrioventricular nodal reentrant tachycardia)
2. Automaticity: MAY see variability, warm up and slow down period, usually a bit lower rate, most will NOT respond to adenosine
a) Ectopic atrial tachycardia
b) J_unctional ectopic tachycardia (JET)_
What is Wolff-Parkinson-White Syndrome?
Pre-excitation syndrome: presence of abnormal accessory electrical conduction pathway (Bundle of Kent) between the atria and ventricles
- pathway conducts electrical activity at higher rate than AV node and thus, if pt had atrial flutter, would conduct all the beats to the ventricles (bypassing the AV node’s natural ability to slow down atrial impulses to protect the ventricles from beating too fast)
- risk of ventricular fibrillation and sudden death
Describe the pathophysiology of AVRT SVT.
- presence of accessory pathway outside of AV node
- normal SA antegrade conduction goes through the AV node and then retrograde up accessory pathway to reactivate the ventricles
- in WPW, normal SA goes antegrade through the accessory pathway bypassing AV node (and thus no normal delay in conduction)
- more likely in < 6 yo
Describe the pathophysiology of AVNRT SVT.
- presence of 2 conducting pathways WITHIN the AV node (one fast and slow) creating a reentrant loop using one pathway in antegrade direction and one in retrograde
- more likely in > 6 yo
Adenosine is only effective at terminating which type of SVT (2)?
Re-entry
- AVRT
- AVNRT
-Adenosine blocks AV node conduction
Why do vagal maneuvers assist in terminating SVTs?
Vagal maneuvers activate parasympathetic nervous system conducted to the heart by the vagus nerve
-increase AV nodal block to eliminate conduction to the ventricles


