Specialty Surgery
[PEDS CT SURGERY]
Introduction Pediatric CT surgery focuses around the defects in cardiac development. That means murmurs. Each murmur has a characteristic sound, appearance, and association . Chest X rays or EKGs may give clues, but all cardiac defects are diagnosed by Echo. Before beginning our discussion of the major cardiac defects, let’s take a moment to go over innocent murmurs. An innocent murmur is NEVER diastolic or > 3/6. Innocent murmurs are always systolic murmurs and low grade (difficult to hear). They can represent any number of high flow states typical in kids. Innocent murmurs don’t need workups. If they persist or no longer meet criteria for innocent they must be worked up with CXR, EKG, and Echo. Left to Right Shunts Left to right shunts are caused by a hole between high and low pressures, allowing blood to flow from the left ventricle (which is oxygenated) back into the pulmonary circulation. This causes increased vascular markings on chest x ray. The response to high pressure in the pulmonary circulation is hypertrophy with resultant pulmonary hypertension. Left alone long enough, there’ll eventually be a flow reversal (Eisenmenger’s) turning these noncyanotic lesions to cyanotic ones.
Murmur or Sxs
EKG CXR ECHO
Echo Gives Dx
Left to Right Shunts Shunts ↑ Pulmonary Flow ↑ Pulmonary Vasculature (CXR) ↑ Pulmonary Pressure Right Ventricular Hypertrophy Eisenmenger’s (Reversal of Flow)
i. Atrial Septal Defect Because the atria are low pressure the consequences are small, so this can be found at any age. The thing that gives it away is the fixed wide split S 2 (easier to say on a test than to identify) and usually the murmur isn’t heard. Closure is achieved either with cath or via surgery. ii. Ventricular Septal Defect This is the most common congenital heart disease. It’s a link between the ventricles (high pressure). There will be a harsh holosystolic murmur. In a kid, there’s been no time for mitral regurgitation to develop (sounds the same) and these are symptomatic young. There’ll be a failure to thrive , dyspnea, or full-blown CHF. If asymptomatic, give it a chance to close spontaneously. If there’s CHF or persistence to 1 year of age surgical correction is mandatory. iii. Patent Ductus Arteriosus A connection between the aorta and the pulmonary artery. Exam reveals a continuous “machinery-like” murmur. The murmur may not be apparent on day one, so may be noticed on the exit exam. If there’s no CHF then the PDA can be closed with indomethacin (ends the PDA). However, if symptoms are severe (high flow, CHF) surgery is needed. The PDA must be closed by 6-8 months regardless. If for some reason a PDA is needed (Tetralogy) prostaglandins can be given to maintain it.
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Specialty Surgery
[PEDS CT SURGERY]
Right to Left Shunts ↓ Pulmonary Flow ↓ Pulmonary Vasculature (CXR) Deoxygenated blood in periphery Blue Baby Syndrome
Right to Left Shunts Something must go very wrong in order for blood to go out into systemic circulation as deoxygenated blood. After all, a simple hole would result in a left to right shunt. So, blood isn’t going to the lungs. This results in cyanosis (blue baby) and decreased vascular markings on chest x-ray. They are the “ T” diseases. They present either with acute cyanosis or chronic effects (such as clubbing). While there are others, these two are most commonly seen, discussed, and tested. iv. Transposition of the Great Arteries The most common cyanotic defect of the newborn. During the first 8 weeks of embryogenesis the heart forms and twists. If it doesn’t twist two independent circulations form: the Vena Cava - RIGHT Ventricle - Aorta (“systemic”) and the Pulmonary Vein – LEFT Ventricle – Pulmonary Artery (“pulmonary”). This means that blood pumped to the periphery isn’t oxygenated; the oxygenated blood is simply circulated through the lungs. Even though it’s common in children of diabetic mothers with poorly controlled sugar it does NOT happen in gestational diabetes (by 20 weeks the heart has already formed). Without a PDA this is fatal (so give prostaglandins ). It presents on day 1 as a blue baby. Surgery must be done to correct it ASAP.
Oxygenated “pulmonary” circulation Deoxygenated “systemic” circulation Vena Cava Pulm Vein
PDA conveys survival
Pulm Artery LEFT Heart
Aorta RIGHT Heart
v. Tetralogy of Fallot The most common cyanotic defect of children (because TGA babies die or get fixed). It’s caused by an endocardial cushion defect. It a “tetra-ology,” and is defined by an 1Overriding 2 3 Aorta, Pulmonary Stenosis, Right Ventricle 4 Hypertrophy, and a Ventricular Septal Defect. If severe we get a blue baby and it requires immediate intervention. The tricky way of presenting is in a toddle with Tet Spells (cyanosis relieved by squatting). Squatting causes an increase in systemic vascular resistance, pushing more right ventricular blood into the lungs. Look for a boot-shaped heart on chest x-ray. This is associated with Down’s Syndrome. Surgery is definitive therapy, held over with a balloon septoplasty. The others are rare. Things like Truncus Arteriosus, Tricuspid Atresia, and TAPVR are almost never seen. Review Step 1 notes for clarity or to impress your attending.
Total Anomalous Pulmonary Venous Return
Coarctation of the Aorta Thrown in here because it doesn’t really fit in either category. In a baby with hypertension , claudication (pain/crying/refusal to walk with walking, relief with sitting), or an obvious temperature difference between arms and legs suspect coarctation. First, get blood pressures on arms and legs; there will be a large disparity. Do an angiogram to definitely diagnose. Surgically correct. If it’s allowed to persist an X ray will show rib notching as collaterals erode into the ribs.
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