For a child known to have uncorrected tetralogy of Fallot presenting with a cyanotic episode, which ONE of the following would NOT be appropriate treatment?
Answer: B: Tetralogy of Fallot results in right heart outflow obstruction, causing right to left shunting and cyanosis. Treatment aims to decrease right to left shunting.
The ideal position for these children is the ‘squatting’ position where afterload is increased, therefore decreasing shunt size. For the same reason, vasoconstrictors such as metaraminol can be used. Crying will increase pulmonary pressures and hence increase right to left shunting. Children with ‘tet’ spells should be kept as calm as possible, usually with parental help. A small fluid bolus will increase RV preload and decrease functional obstruction.
Reference:
Regarding paroxysmal SVT in an infant, which ONE of the following statements is TRUE?
Answer: C: Paroxysmal supraventricular tachycardia represents 90% of tachyarrhythmias in children. The mechanism is due to either an accessory pathway (AV reciprocating tachycardia) or AV nodal reentry; however, accessory pathway is a more common mechanism in children. Some of these children with an accessory pathway may have WPW. These infants usually present to the ED early as they may appear unwell and lethargic. In a stable child vagal manoeuvres may be attempted first. In this age group the vagal manoeuvre commonly used is intermittent placement of a bag filled with ice and some water.
If vagal manoeuvres fail adenosine as an intravenous bolus is used. If this fails other options such as beta-blockers and amiodarone should only be used with caution. Verapamil can cause cardiovascular collapse and death in this age group and therefore should be avoided. If the child is unstable, synchronized cardioversion is the treatment of choice.
References:
Regarding a neonate with an undiagnosed congenital heart disease presenting for the first time to the ED, which ONE of the following statements is TRUE?
Answer: B: A neonate in the first few weeks of life who presents with undifferentiated shock should be presumed as having a duct-dependent congenital heart lesion until proven otherwise while considering all possible other causes of shock in that age group. Duct dependency means the neonate had been dependent on a patent ductus arteriosus to supply partially oxygenated blood to the systemic circulation and the closure of the duct has caused the cardiovascular collapse and shock. This presentation is most common in the first week and rare after 4 weeks of age.
The cyanotic lesions which may be ductal dependent are tetralogy of Fallot, tricuspid atresia and Ebstein’s anomaly, hypoplastic left heart syndrome, interrupted aortic arch and transposition of great arteries without a mixing lesion (e.g. ventricular septal defect, or VSD). Acyanotic lesions that may be ductal dependent are pulmonary stenosis and severe coarctation of the aorta.
Coarctation of the aorta presents with hypertension in the older child. In infancy it may present with congestive cardiac failure. The mainstay treatment for ductal-dependent shock is prostaglandin E1 (PGE1) infusion. Neonates may present with signs of congestive cardiac failure, however, this is not common.
Early soft systolic murmur may indicate a benign murmur, which is common in children. It is believed that significant murmurs in children do not belong to diastolic, late systolic or pansystolic categories.
Regarding the hyperoxia test in a neonate with suspected congenital heart disease, which ONE of the following statements is FALSE?
Answer: A: The hyperoxia test is an important test that should be considered if immediate echocardiography is not available for a neonate who presents to the ED with features of suspected congenital heart disease. Pulse oxymetry alone may be unreliable during this test and arterial blood gas (ABG) sampling is advised. PaO2 is obtained first with the neonate on room air (if not tolerated with a low tolerable amount of supplemental oxygen). PaO2 is then assessed after 100% oxygen supplement for 15 minutes. If PaO2 is >250 mmHg (‘passed hyperoxia test’) on the second ABG it usually excludes hypoxia secondary to congenital heart disease. Another cause for the child’s hypoxia should be sought. PaO2 < 100 mmHg (‘failed hyperoxia test’) is considered to be caused by a right to left shunt due to a cyanotic congenital heart lesion. PaO2 100– 250 mmHg range may be due to intracardiac mixing as a result of a structural heart lesion. A neonate with a failed hyperoxia test needs urgent evaluation for an anatomical diagnosis and should immediately be treated with prostaglandin E1.
Regarding the assessment of children with hypertension, all of the following statements are true EXCEPT:
Answer: A: Childhood hypertension is defined as either systolic or diastolic BP ≥95th percentile of the normal values for the age and the height and BP between 90–95th percentile is defined as pre-hypertension. Although hypertension is an infrequent finding in children presenting to an ED it requires thorough assessment to identify and treat a secondary cause. The aetiology depends on the age. Renal parenchymal disease such as glomerulonephritis is rare in early infancy but it is an important cause in both young and older children. In the neonate, renal vascular thrombosis or stenosis and coarctation of the aorta are important causes. In the older child, once secondary causes are excluded, essential hypertension is considered as the most common cause. Hyperthyroidism and hype-rcortisol states can be life threatening if unrecognized.
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