Alterations in Oxygenation 4

8/4/2019 Alterations in Oxygenation 4

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Alterations in

Oxygenation

Neonate

Congenital Heart Defects

1. Defects with Increased Pulmonary Blood flow

b. Atrial Septal Defect


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b. Atrial Septal Defect- Septal defects are sometimes called a "hole" in

the heart. A defect between the heart's two upperchambers (the atria) is called an atrial septal defect

(ASD).

- the large defect between the atria, causes a largeamount of oxygen-rich (red) blood leaks from the

heart's left side back to the right side; this blood is

pumped back to the lungs, despite already having

been refreshed with oxygen.- this is inefficient, because already-oxygenated

blood displaces blood that needs oxygen. Many

people with this defect have few, if any, symptoms.


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- atrial septal defect is an abnormal

communication between the two atria,

allowing blood to shift from the left to the

right atrium (an acyanotic defect) because of

the stronger contraction of the left side of the

heart.- this causes an increase in the volume in

the right side of the heart and generally results

in ventricular hypertrophy and increasedpulmonary artery blood flow


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-fourth to the sixth week of gestation,

the common atrium is divided into two

chambers.

- the space between these two structures

is called the ostium primum (first hole); as

the first septum continues to grow, a hole

called the ostium secundum (second hole)

appears in its center, eventually it forms the

foramen ovale


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Incidence

- the ratio of atrial septal defect is 1:3; male

to female ratio

- it accounts 9.7% of the congenital heartdiseases or defects


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Altered Hemodynamics

- because left atrial pressure slightly

exceeds right atrial pressure, blood flows from

the left atrium, causing an increased flow of

oxygenated blood into the right side of the

heart- this results to right atrial and right

ventricular hypertrophy

- pulmonary vascular changes usuallyoccur only after several decades if the defect is

unrepaired


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Clinical Manifestations

- characteristic crescendo-decresendo

(harsh) type of systolic murmur over the

second to third intercostal space along the left

sternal border. The murmur is caused by

increased blood flow through the normal

pulmonic valve, not by the blood flow across

the defect


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Assessment and Diagnosis

*physical examination

- the most suggestive sign of atrial

septal defect is its characteristic murmur

*echocardiography

- echocardiography with color flow

Doppler will generally reveal the enlarged sideof the heart and the increased pulmonary

circulation.


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*cardiac catheterization

- cardiac catheterization would revealthe separation in the atrial septum and the

increased oxygen saturation in the right atrium.

*radiography

- Radiographic findings include right atrial

and ventricular hypertrophy.


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Therapeutic Management

- surgical closure of atrial septal defect is reservedfor moderate to large shunts and is done electively

between 1and 3 years of life. It is particularly importantthat atrial septal defect be repaired in girls, because itcan cause emboli during pregnancy.

*open heart surgery

- a cardiopulmonary bypass is done, and theedges of the opening are approximated and sutured.

- the surgery requires the use ofextracorporeal circulation

- if the defect is large, a Silastic or Dacronpatch may be sutured into place to occlude the space

- postoperative complication is unusual, andsurvival is greater than 99%.


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*interventional cardiac catheterization

- closure of an atrial septal defect

using cardiac catheterization with the use of

umbrella tipped catheter.


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Nursing Considerations

- pre-operative preparations

- ensure aseptic technique in the surgical

and invasive management

- post-operatively, carefully carefully

observe the child for arrhythmias in case

edema of the right atrium interferes with SA

node function, which ,may require pacemaker

implantation.


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Thank You

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Alterations in Oxygenation 4