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.

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