Left-Right Shunt Congenital Heart Disease Flashcards

1
Q

Incidence of L-R shunt

A

8/1000 live births (about 1%)

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2
Q

What is the risk of a child with a family history (parents) to develop the disease?

A

10%

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3
Q

What is the risk of a child with a family history (siblings) to develop the disease?

A

2%

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4
Q

What medications increase incidence of CHD?

A

Anticonvulsants, lithium, warfarin, alcohol.

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5
Q

What diseases increase risk of CHD?

A

DMI, Lupus (SLE), rubella, mumps, Coxsackie.

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6
Q

What risk factors in the baby correlate with CHD?

A

Trisomy 21, 13 and 18, Turner syndrome.

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7
Q

Typed of congenital heart disease

A
  1. L-R shunt (pink babies), 2. R-L shunt (blue babies), 3. Obstructive lesions, 4. Arrhythmias
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8
Q

When can CHD be detected on a fetal echo?

A

20 weeks

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9
Q

Types of left to right shunts?

A
  1. Ventricular Septal Defect (VSD), 2. Atrial septal Defect (ASD) 3. Patent Ductus Arteriosus (PDA) 4. Atrio Ventricular Septal Defects (AV canal)
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10
Q

How does pulmonary vascular resistance change between pregnancy and birth?

A

Very high resistance during pregnancy (lungs not inflated). Sharp dramatic drop during first hours after first cry. Continuous drop to normal levels during 4-6 weeks of life.

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11
Q

What is the perimembranous region?

A

Part of muscular intraventricular septum adjacent to membranous septum.

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12
Q

What does the endocardial cushion produce?

A

4 projections like an amoeba: 1. Membranous intraventricular septum, 2. Atroventricular septum, 3. Anterior leaflet of mitral valve, 4. Septal leaflet of TCV.

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13
Q

If a surgeon is told that a patient has a perimembranous outlet VSD, where does he look?

A

Coming from RA to look anteriorly at the level of the pulmonary artery.

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14
Q

What components influence the severity of the VSD shunt?

A

VSD size and Pulmonary resistance

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15
Q

How is the VSD size determined?

A

Compared to baby’s aorta. 60% is large.

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16
Q

What is the clinical presentation of a small VSD?

A

Pansystolic (the smaller the stronger) murmur or no murmur. No problems until after 1st year. Harsh noise but no symptoms.

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17
Q

What is the prognosis for a small VSD?

A

In 60-80% spontaneous closure before 1yo. No treatment. Complications: endocarditis (SBE prophylaxis recommended).

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18
Q

Clinical presentation of moderate and large VSD?

A

Pulmonary resistance is a factor: illness at 4-6 weeks after PR drops. Pressure gradient: L-R shunt. Pansystolic murmur at LLSB or middiastolic murmur at apex. 1st thing seen in echo is increased LA pressure and size because pulmonary veins have a lot of flow. Increasing pressure in LA: backwards flow in pulnmonary veins, alveoli backflow, pulmonary edema- stress situation: tachycardia, tachypnea, sweating (forehead), enlarged liver, difficulty feeding. Slowly, not overnight. CXR: cardiomegaly, enlarge PA, pulmonary edema.

19
Q

Murmur in moderate and large VSD

A

Mitral valve formed by fibrous analous so movement is limited A lot of volume goes through the same size mitral valve creates turbulence and a murmur: 2 murmurs: 1. through VSD in L-R ventricle-pansystolic; and 2. diastolic murmur when extra flow passes from LA to LV through undilated mitral valve.

20
Q

Treatment of moderate/large VSD

A

Frequent feedings with added calories. Medications.

21
Q

What medications treat VSD?

A
  1. Preload: diuretics. 2. Contractility: inotropes (Digoxin), 3. Afterload (mercaptopurine)
22
Q

Types of surgical treatment of VSD

A

Palliative (Pulmonary Artery Banding-PAB) or Curative (Primary repair)

23
Q
A
24
Q

Pulmonary artery banding (PAB)

A

Small surgery, closed chest. Enter pulmonary artery through axila. Place band around pulmonary trunk and decrease diameter, increasing resistance. Right side has to create more pressure and shunt decreases.

25
Q

What is the relative mortality between PAB and primary repair?

A

0.1% vs 3-5%

26
Q

Problems with PAB

A
  1. If band is too tight get reversal of flow from right to left, 2. Too loose: excessive flow to pulmonary arteries continues, 3. May confuse PA with aorta and banding the aorta would be bad, 4. Area around band grows abnormally and PA distorts-need to do plastic surgery
27
Q

Curative treatment-primary repair of VSD

A

Open chest, open heart, on heart-lung machine, patch over VSD.

28
Q

Complications of VSD

A

Endocarditis (small VSD), Eisenmenger syndrome.

29
Q

Why does endocarditis occur in a small VSD?

A

Jet goes from LV to RV, will create lesions in the endocardium across from the VSD on the right RV wall and in trajectory points superiorly and inferiorly off an arc. Bacteria can form in these lesions, form abscess in heart and throw bacteria around the body. Difficult to treat: IV antibiotics for 6 weeks.

30
Q

What is the pulmonary reflex to the VSD?

A

LR shunt from pulmonary artery: PA protects itself from increased flow by decreasing lumen of pulmonary arteries. When there is increased flow, reflex tries to decrease flow and the pulmonary arteries will contract. PA lumen will decrease with increased resistance and creating less flow into the pulmonary circulation. Temporary process: wall will dilate again after pulm circ is decreased.

31
Q

Eisenmenger syndrome

A

If pulmonary circulation is decreased from VSD for more than 2 years, will not be reversible because fibers and muscle will grow and decrease PA diameter. This is usually in small arteries so hard to treat surgically. Resistance in the pulmonary trunk, pressure decreases, shunt is diminshed. Honeymoon period, not reversible: Pt is cyanotic because of reversal of shunt into R-L shunt. At this stage, you cannot close the VSD-irreversible! Need to have it open because if there is occlusion in the PA the blood can shift across. Can’t close it.

32
Q

What is the cure for Eisenmenger syndrome?

A

Heart and lung transplant.

33
Q

When does ASD produce symptoms?

A

3rd or 4th decade of life. Often found in army physical.

34
Q

Where is the anatomical problem in ASD?

A

Nonclosure of the septum primum between the LA and RA. RA is more compliant to receives blood.

35
Q

Whats is enlarged from an ASD?

A

Right ventricle (right side) and pulmonary artery. RV heave. Cardiomegaly.

36
Q

What sort of murmur is common in ASD?

A

In pulmonary valve from excessive flow. Valve can’t enlarge because fiber and not muscle. Second heart sound widely split: P2 far from A2. Pulmonic ejection murmur. Otehrwise middiastolic murmur at tricuspid valve.

37
Q

What ECG appearances are in ASD?

A

RVH, Right axis deviation, ICRBBB.

38
Q

What is the treatment for ASD?

A

Spontaneous closure (but less than VSD) otherwise surgery/catheterization. If secundum: catheterization at 4yo because of size of vein depending on risk. Umbrella closure.

39
Q

What is ASD Primum?

A
  1. Isolated, 2. Partial with cleft mitral valve. 3. Complete: one component of AV septal defect, most common in Down Syndrome. Left-right shunt, pulmonary hypertension earlier (in Down’s: hypotonia, hypoplasia of lungs, frequent infections).
40
Q

Where does a patent ductus arteriosus allow blood to flow?

A

From aorta to pulmonary circulation during systole at 120mmHg and diastole at 80.

41
Q

When does the ductus arteriosus usually close?

A

3-4 days

42
Q

Where is a murmur heard in PDA?

A

Left upper sternal border (subclavicular)

43
Q

What are the symptoms of the PDA similar to?

A

VSD

44
Q

What is the treatment for PDA?

A

Spontaneous closure in 3-4 weeks. Indomethacin in premature babies to reduce prostaglandins. If more than a month: ligation, catheter closure with coil.