Cardiac dysfunction

3. Purpose of various tests and procedures in diagnosing cardiac dysfunction (p.1345-1349)

Radiologic imaging (chest x-ray) –

Most frequently ordered radiologic test for children with suspected cardiac problems.

Provides permanent record of heart size, configuration, its chambers, great vessels

Provides pattern of blood flow, especially in pulmonary vessels

Electrocardiography (ECG)

Graphic measure of electrical activity of heart

Information supplied by results include: heart rate and rhythm, indications of conduction abnormalities, muscular damage (ischemia), hypertrophy, electrolyte imbalance, effects of various drugs, and pericardial disease.

The ECG gives NO DIRECT information about the mechanical performance of the heart as a pump

Procedure: ECG is taken by placing leads (electrodes) on the skin to transmit electrical impulses back to a recording machine.

(smoke over fire, clouds over grass, brown in the middle)

For continuous ECG monitoring, electrodes should be changed every 1 to 2 days because they can irritate the skin.

Holter recording is used when children have daily symptoms of a potential arrythmia. Records the heart rhythm for 24 to 72 hours. Instruct parents to keep daily log of activity to determine link between rhythm and physical activity

Echocardiography

One of the most frequent used procedures for detecting cardiac dysfunction in children.

Defects can be diagnosed prenatally with fetal echocardiography

Involves the use of high frequency sound wave sto produce an image of the heart's structure

Transducer placed directly on chest wall delivers repetitive pulses of ultrasound and processes that returned signals (echoes)

Test is non-invasive and pain free, associated with no known side effects. But can be stressful for children.

Child must lie quietly in the standard positions, crying nursing or sitting up leads to errors or omissions. Therefore, younger children or infants may need a sedative.

Cardiac Magnetic Resonance Imaging (CMRI)

When echocardiography may be limiting, especially in the case of a child that may have poor acoustic windows or difficult and complex structure that are difficult to visualize by ultrasound alone, MRI is often used to define unresolved anatomic pathways

Can often be used in place of cardiac catheterization and obtain true three dimensional angiography.

Non invasive but children may require anesthesia, deep sedation or conscious sedation. Developmental age and maturity are often primary consideration.

Cardiac Catheterization

Most invasive diagnostic procedures

Radiopaque catheter is inserted through a peripheral blood vessel into the heart

Usually combined with angiography, in which a radiopaque contrast material is injected through the catheter and into the circulation.

Provides information regarding oxygen saturation in blood within the chambers and great vessels, pressure changes within these structures, cardiac output or stroke volume, anatomic abnormalities (septal defects, obstruction to flow)

Two main types of cardiac catheterization are: right sided or venous, in which the catheter is introduced from a vein in to the RA and left sided or arterial catheterization in which the catheter is threaded by a systemic artery retrograde into the aorta and LV.

Usually introduced through a puncture into the femoral vein. Once the vessel is entered, the catheter is guided through the eart with the aid of fluoroscopy. As the tubing is advanced, th child may feel pressure at the insertion site and vasospams (fluttering) of small vessels.

PRETTY GOOD TABLE ON IN BOX 34-1 (page 1346) – that sums it all up pretty good.

6. Causes for, clinical manifestations of, and treatment of heart failure (p.1352-1356)

Causes for:

- The child exhibits signs of HF because of decreased myocardial contraction, increased preload, and increased afterload.

- Most infants diagnosed with HF is because of congenital heart defect

Clinical Manifestations:

- The signs and symptoms of HF are divided into three groups: 1) Impaired myocardial function, 2) Pulmonary congestion 3) systemic venous congestion

- Impaired myocardial function as a result of sympathetic stimulation

- Impaired Myocardial function: Tachycardia, Sweating, decreased urinary output, fatigue, weakness, restlessness, anorexia, pale cool extremities, weak periperhal pulses, decreased blood pressure, gallop rhythm, cardiomegaly

- Pulmonary congestion occurs in response to decreased lung compliance (ability to expand).

- Pulmonary congestion: Tachypnea, dyspnea, Retractions (infants), flaring nares, exercise intolerance, orthopnea, cough, cyanosis, wheezing, grunting

- Systemic venous congestion from right sided failure results in increased pressure and pooling of blood in the venous circulation.

- Systemic venous congestion: Weight gain, hepatomegaly, peripheral edema especially periorbital, Ascites, neck vein distention (children)

- Hepatomegaly occurs from pooling of blood in the portal circulation and transudation of fluid into the hepatic tissues. The liver may be tender on palpation and its size is an indication of the course of heart failure.

Treatment of Heart failure

Goals of treatment are: improve cardiac function (increase contractility and decreased afterload), remove accumulated fluid and sodium (decrease preload), decrease cardiac demands, and improve tissue oxygenation and decrease oxygen consumption.

9. Describe cardiac defects characterized by increased pulmonary flow: ASD< VSD< PDA< Coarctation of aorta, Aortic stenosis, pulmonic stenosis (p. 1366-1370)

ASD (Atrial spetal defect)

Abnormal opening between the atria, allowing blood from the higher pressure left atrium to flow into the lower pressure right atrium.

Patients may be asymptomatic. May develop HF in third or fourth decade of life if ASD goes undiagnosed.

There is a characteristic murmur

Patients are at risk for atrial dysrhythmias

Surgical treatment: Surgical patch closure is done for moderate to large defects. Open repair with cardiopulmonary bypass is usually performed before school age.

Nonsurgical treatment: ASD 2 closure with a device during cardiac catheterization is becoming commonplace and can be done as outpatient.

Prognosis – operative mortality is very low.

VSD (Ventrical Septal Defect)

Abnormal opening between the right and left ventricles. May be classified according to location, mebranous or muscular.

VSD are frequently associated with other defects.

Because of the higher pressure within the left ventricle and because the systemic arterial circulation offers more resitance than the pulmonary circulation, blood flows through the defect into the pulmonary artery. The increased blood volume is pumped into the lungs, which may eventually result in increased pulmonary vascular resitance.

Clinical manifestations: HF is common. There is a characteristic murmur

Surgical treatment includes palliative, complete repair, and nonsurgical treatment.

Prognosis: Risks depend on the location of the defect, the number of defects, and the presence of other associated cardiac defects. Single membranous defects are associated with low mortality.

PDA – Patent Ductus Arteriosus

Failure of the fetal ductus arteriosus (artery connecting the aorta and pulmonary artery) to close within the first few weeks of life. The continued patency of this vessel allows blood to flow from the higher pressure aorta to the lower pressure pulmonary artery which causes a left to right shunt.

Clinical manifestations: Patients may be asymptomatic or show signs of HF. There is a characteristic machinery like murmur. A widened pulse pressure and bounding pulses result from runoff of blood from the aorta to the pulmonary artery. Patients are at risk for infective endocarditis and pulmonary vascular obstructive disease in later life from chronic excessive pulmonary flow.

Medical management- administration of indomethacin (prostaglandin inhibitor)

Surgical treatment – surgical division or ligation of the patent vessel is performed via a left thoracotomy.

Nonsurgical treatment: Coils to occlude the pDA are placed in the catherterization laboratory in many centers. Premature or small infants and patients with large or unusual PDAs may require surgery.

Prognosis Both surgical and non surgical low risk at mortality less than 1%

Coarctation of the Aorta

Localized narrowing near the insertion of the ductus arteriosus which results in increased pressure proximal to the defect (head and upper extremities) and decreased pressure distal to the obstruction (body and lower extremities)

Clinical manifestations: There may be high blood pressure and bounding pulses in the arms, weak or absent femoral pulses, and cool lower extremities with lower blood pressure. There are signs of HF in infants. Older children

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