Left-Right Shunt Congenital Heart Disease

Question 1

Incidence of L-R shunt

Answer 1

8/1000 live births (about 1%)

Question 2

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

Answer 2

10%

Question 3

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

Answer 3

2%

Question 4

What medications increase incidence of CHD?

Answer 4

Anticonvulsants, lithium, warfarin, alcohol.

Question 5

What diseases increase risk of CHD?

Answer 5

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

Question 6

What risk factors in the baby correlate with CHD?

Answer 6

Trisomy 21, 13 and 18, Turner syndrome.

Question 7

Typed of congenital heart disease

Answer 7

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

Question 8

When can CHD be detected on a fetal echo?

Answer 8

20 weeks

Question 9

Types of left to right shunts?

Answer 9

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

Question 10

How does pulmonary vascular resistance change between pregnancy and birth?

Answer 10

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.

Question 11

What is the perimembranous region?

Answer 11

Part of muscular intraventricular septum adjacent to membranous septum.

Question 12

What does the endocardial cushion produce?

Answer 12

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

Question 13

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

Answer 13

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

Question 14

What components influence the severity of the VSD shunt?

Answer 14

VSD size and Pulmonary resistance

Question 15

How is the VSD size determined?

Answer 15

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

Question 16

What is the clinical presentation of a small VSD?

Answer 16

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

Question 17

What is the prognosis for a small VSD?

Answer 17

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

Question 18

Clinical presentation of moderate and large VSD?

Answer 18

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.

Question 19

Murmur in moderate and large VSD

Answer 19

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.

Question 20

Treatment of moderate/large VSD

Answer 20

Frequent feedings with added calories. Medications.

Question 21

What medications treat VSD?

Answer 21

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

Question 22

Types of surgical treatment of VSD

Answer 22

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

Question 24

Pulmonary artery banding (PAB)

Answer 24

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.

Question 25

What is the relative mortality between PAB and primary repair?

Answer 25

0.1% vs 3-5%

Question 26

Problems with PAB

Answer 26

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

Question 27

Curative treatment-primary repair of VSD

Answer 27

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

Question 28

Complications of VSD

Answer 28

Endocarditis (small VSD), Eisenmenger syndrome.

Question 29

Why does endocarditis occur in a small VSD?

Answer 29

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.

Question 30

What is the pulmonary reflex to the VSD?

Answer 30

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.

Question 31

Eisenmenger syndrome

Answer 31

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.

Question 32

What is the cure for Eisenmenger syndrome?

Answer 32

Heart and lung transplant.

Question 33

When does ASD produce symptoms?

Answer 33

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

Question 34

Where is the anatomical problem in ASD?

Answer 34

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

Question 35

Whats is enlarged from an ASD?

Answer 35

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

Question 36

What sort of murmur is common in ASD?

Answer 36

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.

Question 37

What ECG appearances are in ASD?

Answer 37

RVH, Right axis deviation, ICRBBB.

Question 38

What is the treatment for ASD?

Answer 38

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

Question 39

What is ASD Primum?

Answer 39

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).

Question 40

Where does a patent ductus arteriosus allow blood to flow?

Answer 40

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

Question 41

When does the ductus arteriosus usually close?

Answer 41

3-4 days

Question 42

Where is a murmur heard in PDA?

Answer 42

Left upper sternal border (subclavicular)

Question 43

What are the symptoms of the PDA similar to?

Answer 43

VSD

Question 44

What is the treatment for PDA?

Answer 44

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