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23 Cards in this Set
- Front
- Back
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Why does an aortic atresia cause significant underdevelopment of the left ventricle and aorta?
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This is an obstruction, which leads to significantly less blood flow through the area. Blood flow is needed to stimulate growth.
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Will a septal defect favor L to R or R to L shunting?
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L to R shunting - high to low pressure.
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What is the cause of dilation in a developing heart?
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excessive blood flow
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Define shunt
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Shunting refers to an abnormal mixing of blood between L and R heart structures.
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Why does a patient not become cyanotic with a L to R shunt?
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In this type of shunt, a portion of the oxygenated blood is shunted back through the pulmonary system. *All blood leaving the aorta is oxygenated*
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Explain why R to L shunting causes cyanosis.
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Deoxygenated blood from the R side of the heart enters the L side of the heart, bypassing pulmonary circulation.
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Name an example of a congenital R to L shunt.
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Tricuspid atresia with RA to LA shunting.
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True or false: it is easy to spot a patient with cyanosis.
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False - a low O2 sat can cause very subtle signs of cyanosis and testing is necessary to rule out cyanosis.
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How can you differentiate respiratory from central causes of cyanosis?
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Give oxygen: if the pt improves, the cause of cyanosis is respiratory. If the patient does not improve, the cause is central.
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Name the three main types of VSDs.
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1. Perimembranous - involves membranous septum, roofed by aortic valve
2. Muscular - surrounded by muscle 3. Inlet - bordered by the tricuspid valve. Typically part of an atrioventricular septal defect |
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What causes L to R shunts to become worse over the first few weeks of life?
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Decreasing pulmonary vascular resistance.
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Name at least three signs of CHF in infants.
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-tachypnea
-increased work of breathing -tachycardia -failure to thrive or poor weight gain -hepatomegaly (cyanosis and edema are not usually present in infants with CHF, unless they are in mulisystem organ failure) |
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Describe the pathophysiology of pulmonary congestion due to a large L to R shunt.
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-A large volume of blood enters the pulmonary circulation (from system circulation and from the L side of the heart).
-This causes pulmonary arterial congestion. -Pulmonary interstitium becomes congested. -This causes decreased lung compliance and therefore more work is required to inflate the lungs. -Additionally, over time more vessels develop in the lungs to compensate. These can be counterproductive as they can actually cause a compressive force, reducing compliance further. *Keep in mind that a different mechanism is responsible for pulmonary venous congestion. |
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Do infants have stiffer or more pliable cardiac tissue, with comparison to adults?
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Stiffer - this makes it more difficult to increase stroke volume. Instead, infants are more likely to have tachycardia when an increase in CO is needed.
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Why do infants with CHF often have diaphoresis?
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A decrease in cardiac output causes increased sympathetic activity.
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What is the most common cause of CHF in infants?
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Excessive pulmonary blood flow.
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Describe the management of CHF in infants.
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Provide nutritional support - high calorie feed, tube feed, if necessary.
Heart failure meds - diuretics, other targeted treatments including beta blockers, ACE inhibitors, antiarrhythmics If medical therapy does not work sufficiently, surgery should be the next step, to close the defect. |
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Do all VSDs require intervention?
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No, many small VSDs will eventually close spontaneously or will not cause significant Sx.
A hemodynamically significant VSD will present by 3-4 months |
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When can CHD be present?
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at birth
during the first week (ductus related) in early infancy (PVR related L-R shunts) when there is maladaption or decompensation |
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In an infant with a complex heart defect, what treatment is given to maintain the ductus arteriosis?
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Prostaglandin (treatment was developed in Canada).
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How can you recognize coarctation of the aorta during physical examination of an infant?
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The infant will have normal brachial pulses and weak femoral pulses.
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What is the key element of an atrioventricular septal defect (AVSD)?
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A common, abnormal atrioventricular valve.
one valve with 5 leaflets There will be an ASD and a VSD but the hallmark is a single mitral/tricuspid valve |
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How long does it take for the patent ductus arteriosis (PDA) to close (and subsequently cause decompensation of PDA-dependent defects)?
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48-72 hours
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