Tetralogyof fallot

Tetralogy of fallot

INTRODUCTION

qOne of the first types of congenital heart defects

qInvolves four anatomical anomalies pulmonary stenosis ventricular septal defect overriding of aorta right ventricular hypertrophy

qMost common cyanotic heart defect (55-70%) q qDescribed in 1672 by Niels Stensen 1773 by Edward Sandifort 1888 by Etien-Louis Arthur Fallot

EPIDEMIOLOGY

Occurs 400/million

live births

Etiology

Chromosome 22

deletions

ANATOMY and PHYSIOLOGY

Fetal Circulation Thecirculatory systemof a humanfetusworks differently from that of born humans, mainly because the lungs are not in use: thefetusobtainsoxygenand nutrientsfrom the mother through the placentaand theumbilical cord.

Blood from theplacentais

carried to thefetusby theumbilical vein. About half of this enters the

fetalductus venosusand is carried to the inferior vena cava, while the other half enters theliverproper from

The ductus venosus then

merges to the inferior vena cava, mixes with the deoxygenated blood, and travels to the right atrium. In the fetus, there is an opening between therightandleft atrium(theforamen ovale), and most of the blood flows through this hole directly into the left atrium from the right

The continuation of this blood

flow is into the left ventricle, and from there it ispumpedthrough theaortainto the body. Some of the blood moves from the aorta through theinternal iliac arteriesto theumbilical arteries, and re-enters the placenta, wherecarbon dioxideand other waste

Some of thebloodentering the

right atrium does not pass directly to theleft atriumthrough theforamen ovale, but enters theright ventricleand is pumped into thepulmonary artery. In the fetus, there is a special connection between thepulmonary arteryand theaorta, called theductus arteriosus, which directs most of this blood away from the lungs (which aren't being used

PATHOPHYSIOLO GY

FORAMEN OVALE

Normally this opening closes in the first three months of life. When the lungs become functional at birth, the pulmonary pressure decreases and the left atrial pressure exceeds that of the right. This forces the septum primum against the septum secundum, functionally closing the foramen ovale. In time the septa eventually fuse, leaving a remnant of the

PULMONARY STENOSIS narrowing of the right ventricular outflow tract and can occur at thepulmonary valve(valvular stenosis) or just below thepulmonary valve(infundibular stenosis). The pulmonic stenosis is the major cause of the malformations, with the other associated malformations acting as compensatory mechanisms to the pulmonic

OVERRIDING AORTA Anaortic valvewith

biventricular connection, that is, it is situated above the ventricular septal defect and connected to both the right and the left ventricle. The degree to which the aorta is attached to the right ventricle is referred to as its degree of "override." right ventricle.

VENTRICULAR SEPTAL DEFECT A hole between the two bottom chambers (ventricles) of the heart. The defect is centered around the most superior aspect of the ventricular septum (the outlet septum), and in the majority of cases is single and large. In some cases thickening of the septum (septal hypertrophy) can narrow the margins of the

RIGHT VENTRICULAR

HYPERTROPHY Theright ventricleis more muscular than normal, causing a characteristic boot-shaped (coeur-en-sabot) appearance as seen by chest X-ray. Due to the misarrangement of the external ventricular septum, the right ventricular wall increases in size to deal with the increased obstruction to the right outflow tract. This feature is now generally agreed to be a

PULMONARY STENOSIS-RIGHT VENTRICULAR HYPERTROPHYVENTRICULAR SEPTAL DEFECTOVERRIDING OF THE AORTA

mixing of oxygenated and deoxygenated blood in the left ventricle via the VSD

preferential flow of the mixed blood from both ventricles through the aorta because of the obstruction to flow through the pulmonary valve

Diagnostic Tests and Procedures

EchocardiographyEchocardiography(echo) is a painless test that

uses sound waves to create a moving picture of the heart. During the test, the sound waves (called ultrasound) bounce off the structures of the heart. A computer converts the sound waves into pictures on a screen. tetralogy of Fallot because it shows the four heart defects and how the heart is responding to them. This test helps the cardiologist decide when to repair these defects and what type of surgery is needed.

Echo is an important test for diagnosing

EKG ( Electrocardiogram ) AnEKGis a simple, painless test that records

the hearts electrical activity. The test shows how fast the heart is beating and its rhythm (steady or irregular). It also records the strength and timing of electrical signals as they pass through each part of the heart.

Chest X RayThe abnormal "coeur-en-sabot" (boot-like)

appearance of a heart with tetralogy of Fallot is easily visible via chest x-ray, and before more sophisticated techniques became available, this was the definitive method of diagnosis. Congenital heart defects are now diagnosed with echocardiography, which is quick, involves no radiation, is very specific, and can be done prenatally.

Pulse Oximetry For this test, a small sensor is attached to a

finger or toe (like an adhesive bandage). The sensor gives an estimate of how much oxygen is in the blood.

Cardiac Catheterization

The doctor also can use cardiac catheterization

to measure the pressure and oxygen level inside the heart chambers and blood vessels. This can help the doctor determine whether blood is mixing between the two sides of the heart.

MEDICAL MANAGEMENT

GOALS OF TREATMENT

Improve the babys symptoms Increase the level of oxygen in

the babys blood Repair the defects

DigoxinIndication: cardiac failure accompanied

by atrial fibrillation; management of chronic cardiac failure where systolic dysfunction is dominant D: 25/35 mcg/kg CI: intermittent complete heart block or 2nd degree AV block ; arrhythmia caused by cardiac glycoside intoxication; hypersensitivity to other digitalis glycosides SP:severe respiratory distress;hypoxia

AR: CNS disturbances, dizziness,

visual disturbances ; arrhytmia, conduction disturbances, sinus bradyccardia, nausea, vomiting, diarrhea

SURGICAL MANAGEMENT

Corrective Surgery-Closing

the VSD Opening and enlarging the area that blood flows through as it leaves the lower right side of the heart Opening or widening the pulmonary valve

Temporary or Palliative Surgery -

As small opening can be made between the ribs. Place a tube/shunt between a large artery branching off the aorta and the pulmonary artery The shunt is removed when the babys heart defects are repaired during the corrective surgery

NURSING CARE PLAN

CUES: CR more than 160 bpm DIAGNOSIS: Decreased cardiac output r/t ineffective circulationBACKGROUND KNOWLEDGE

Tetralogy of The patient Assess and Fallot will have record the results in adequate vital signs low cardiac oxygenation output as of blood due evidenced to mixing of by cardiac oxygenated rate within and normal deoxygenated range blood in the left ventricle through the VSD

OBJECTIV E

INTERVENTION RATIONAL

EVALUATION

E

If the patient experiences decreased cardiac output, the cardiac rate, respiratory rate will increase and the bp will decrease.

BACKGROUND KNOWLEDGE

OBJECTIV E


EVALUATION

E

and preferential flow of both oxygenated and deoxygenated blood from the ventricles through the aorta because of obstruction to flow through the pulmonary valve.

Administer cardiac drugs as ordered

Cardiac drugs are given to increase the strength of cardiac contraction s and/or increase return of blood flow to the heart, thereby increasing CO.


OBJECTIV E


EVALUATION

E

Monitor and record digoxin levels. Notify physician if levels are out of acceptable range.

Digoxin is a potent medication that needs careful monitoring. If digoxin levels are high, the patient will experience s/s of toxicity such as vomiting.


OBJECTIV E


EVALUATION The patients cardiac rate is within acceptable range.

E

Keep accurate record of intake and output

Decreased output may indicate decreased CO possibly due to a shift of the intravascul ar fluid into the interstitia l space.

CUES: Abnormal heart rate/blood pressure response to activity; exertional dyspnea DIAGNOSIS: Activity intolerance related to imbalance oxygen supply and demand.BACKGROUND KNOWLEDGEBecause of the shunting between the ventricles, the mixing of the oxygenated and unoxygenated blood results to less oxygen supplied for the tissues. This results to easy fatigability and cyanosis whenever the infant exerts effort.

OBJECTIV INTERVENTION RATIONALE EVALUATION E The Assess Indicates child dyspnea on hypoxia and will exertion, increase tolerate skin color oxygen need increase changes during d during energy activity . rest and expenditure. when active.


OBJECTIV E

INTERVENTION RATIONALE

E VALUATION

Allow rest Promotes periods rest and between conserves cares; disturb energy. only for care and necessary procedure.


OBJECTIV E

INTERVENTION RATIONALE

E VALUATION

Avoid Conserves allowing energy. infant to cry Cross-cut for a long period of nipple time; use requires soft nipple for feeding; less energy for infant cross-cut nipple; if to feed. unable for infant to ingest sufficient calories by mouth, gavage-feed infant.


OBJECTIVE INTERVENTION

RATIONALE EVALUATION

Provide Avoid neutral extremes environmental heat and temperature; cold that when bathing increases exposed only oxygen and area being energy bathed and needs. keep the infant covered to prevent heat loss.


OBJECTIVE INTERVENTION

RATIONAL E

EVALUATIO N

Explain to Avoids parents need fatigue to conserve energy and encourage rest.

The patient s activity level is optimal within the Provides limitatio Assist ns of the parents to rest and avoids over disease . plan for exertion, minimizes care and rest periods. energy expenditure.

Documents

Tetralogyof fallot