Congenital Heart Defects (CHD)

• Congenital heart defect (CHD) is a malformation of the heart existing at birth
• CHD results from the failure of the heart or major blood vessel to mature properly during gestation
• CHD affects 25,000-30,000 children per year, or 8 out of every 1,000 births
• CHD is a major cause of death in the first year and the most common congenital malformation in newborns
• Sex is affected differently depending on the defect:
  • Male - AS, COA and TGV
  • Female - PDA and ASD
• Children with CHD have increased liklihood of extracardiac defects like tracheoesophageal fistula, renal agenesis, and diaphragmatic hernias

Etiology

• Exact cause of CHD is unknown
• Genetic and environmental factors associate with a higher incidence of the disease
• Genetic factors influencing are multifactorial
  • Sibling or parent with heart defect
  • Chromosomal aberrations = half of all babies with Down syndrome have congenital heart defects
  • Born with other congenital anomalies
• Prenatal Influences
  • Viral infection during pregnancy, especially rubella in the first trimester
  • Fetal exposure to drugs like alcohol, lithium, acutane, cocaine, and antiseizure medications
  • Maternal age over 40 years old
  • Maternal metabolic disorders like type 1 DM and PKU

Pediatric Differences

• Fetal tissues are accustomed to low oxygen saturation
  • Newborns with cyanotic heart disease may appear comfortable when pO2 is 20-25 mmHg
  • Older children, death could occur in minutes
• At 2 months of age, the left ventricle (LV) is twice the size of the right ventricle (RV)
• Infant heart muscle fibers are less developed and organized leading to higher risk of heart failure due to:
  • Immature heart's sensitivity to volume or pressure overload
  • Limited functional capacity that reduces the ability to increase stroke volume substantially
• By age 5, heart muscle fibers are developed, making the heart comparable to a healthy adult
• The cardiac output depends on heart rate until muscle fibers are fully developed at 5 years old
• Oxygen requirements are high in the first few weeks, leading to increased heart rate to provide adequate oxygen transport
• Children respond to severe hypoxemia with bradycardia leading to cardiac arrest

Diagnostic Procedures

• History
• Physical Exam
• Chest X-ray
• ECG
• Echocardiography
• Cardiac Catheterization
• Exercise Stress Test
• Cardiac MRI
• CBC and ABG

History

• Possible causes of CHD
• Poor weight gain or feeding behavior
• Frequent respiratory infections
• Prior murmurs
• Respiratory difficulties; tachypnea, dyspnea, and SOB
• Cyanosis
• Exercise intolerance or fatigue

Physical Exam

• Inspect the nutritional state
  • Failure to thrive, poor weight gain
  • Color; cyanosis and pallor
  • Distorted chest configuration; enlarged heart
  • Unusual pulsations; visible neck veins
  • Respiratory difficulties
  • Clubbing of fingers
• Palpate thrills, hepatomegaly, and peripheral pulses for rate, regularity and discrepancies
• Auscultate the heart rate and rhythm, and character of sounds/murmurs

Chest X-Ray

• Provides information on heart size and pulmonary blood flow markings

ECG

• Graphic measurement of electrical activity of the heart
• Use Holter monitor or 24 hour continuous ECG recording to assess dysrhythmias

Echocardiography

• Use of high-frequency sound waves obtained by a transducer to produce image of cardiac structures
• Types of echocardiography-
  • Transthoracic, done with transducer on chest
    • M mode is one dimensional graphic view used to estimate ventricular size and function
    • Two-dimensional is real-time, cross sectional views of the heart to identify cardiac structures and anatomy
    • Doppler identifies blood flow patterns and pressure gradients across structures
    • Fetal - imaging fetal heart in utero
    • Transesophageal - Transducer placed in esophagus to obtain images of posterior heart structures or in patients with poor images from chest approach

Cardiac Catheterization

• An imaging study using radiopaque catheters placed in a peripheral blood vessel and advanced into the heart
• Performed on an OP basis

Purposes of Cardiac Catheterization

• Diagnostic for detecting CHD prior to surgical repair
  • A right-sided catheterization is more common and via femoral vein access
    • A left sided catheterization, is via artery aorta and heart
  • Hemodynamics measures pressures and oxygen saturations in heart chambers
  • Angiography - a contrast material is used to illuminate heart structures and blood flow patterns
• Biopsy uses a special catheter to remove tiny samples of heart muscle for microscopic evaluation, which assesses for:
  • Infection
    • Inflammation
    • Muscle dysfunction disorders
    • Also evaluates for rejection after heart transplant
• Electrophysiology uses special catheters with electrodes which records electrical activity from within the heart to diagnose rhythm disturbances
• Interventional/Therapeutic uses a balloon catheter or other devices to alter cardiac anatomy
  • Dilate stenosed valves or vessels
  • Close abnormal openings

Manner of Introduction of Catheter

• Cutdown
• Percutaneous, where a catheter is threaded through a large bore needle that is inserted in to the vein
  • Guided through the heart with the aid of fluoroscopy
  • Once tip is in the heart chamber, contrast medium is injected and films are taken
  • Complications include perforation of pulmonary artery, allergic reaction to contrast media, dysrrhythmias, hypotension, stroke, vascular compromise in the leg,and bleeding

Nursing Care Before Cardiac Catheterization

• Monitor height and weight for catheter selection
• Check history for allergy to iodine-based contrast medium
• Assess for infection indicating the need to cancel procedure if femoral access is necessary
• Keep NPO past midnight
• Void before entering catheter lab/room
• Assess and mark pulses for baseline data
• Administer IV fluids to prevent dehydration and hypoglycemia especially for patients with polycythemia
• Offer Sedative either IV or oral

Nursing Care During Cardiac Catheterization

• Groin cleansed with a special brown solution
• Medications are given to numb the skin
• A tube is put in the blood vessel, a feeling of pushing may be felt
• Contrast dye medicine causes a feeling of warmth
• Lights will go off when the medicine is put in and pictures are taken

Nursing Care After Cardiac Catheterization

• Monitor VS every 15 minutes and Emphasis HR
  • Count for a full minute due to dysrhythmias/bradycardia
• Pulses especially below the cath site for symmetry and equality
  • First few hours pulses maybe weaker but should gradually increase in strength
• Check the temperature and color of affected extremity
  • Coolness and blanching = arterial obstruction
• Monitor the BP
  • Hypotension could indicate hemorrhage due to cardiac perforation or bleeding at the site of initial catheterization
• Be aware of dressing -bleeding or hematoma formation
• Fluid intake (IV/PO) needs to be watched
  • Ensure adequate hydration due to blood loss from procedure, NPO status and diuretic action of dye used
• Be aware of Hypoglycemia
• Affected extremity must be kept straight to facilitate the healing process
  • 4-6 hours after venous catheterization
  • 6-8 hours for arterial
• Maintain the same Diet being resumed as tolerated
  • Sips of clear liquids to usual
• Encourage to void to clear contrast material
• Pressure dressing to be removed the day after catheterization
  • Followed by Site being covered by adhesive bandage strip for several days
• Prevent infection
  • Keep the site clean and dry and must be protected from contamination
• Avoid tub baths for several days and have a shower
• Monitor for redness, swelling, and drainage

Exercise Stress Test

• Exercise stress test and Cardiac Magnetic Resonance Imaging(MRI) are also diagnostic

Cardiac Magnetic Resonance Imaging(MRI Characteristics

• Newer noninvasive imaging technique being utilized in the evaluation of vascular anatomy outside the heart

Complete Blood Count and Arterial Blood Gas

• In types of congenital heart defect CBC and ABG show increased Hgb and Hct due to polycythemia

Types of Congenital Heart Defects

• CHD can manifest in a mild form(no outward symptoms) and severe where transplants is needed
• CHD pathophysiology is related to hemodynamics
• Fluid with blood flow toward the path of least resistance
• Higher Pressure can determine a rapid rate of flow
  • Increased resistance is a reduction of flow

Abnormal pressure that creates a connection allows blood to flow from high to low pressure

Types of Congenital Heart Defects

• If L->R SHUNT it equals acyanotic defect
• If R->L SHUNT will be classified as a cyanotic defect

Cyanotic Defects

• Allows unoxygenated blood towards the systemic circulation creating obstructive pulmonary blood flow
• Unoxygenated in the body lowers zero two levels which causes cyanosis Magnificent T’s: - Reduced Pulmonary Blood Flow -Tetralogy of Fallot- The VSDs

Assessment:

• Best recognized in the tongue and Mucosa Membrane
• Difficult feeding
• Limited growth
• Diagnostic for TOF is a squat
• Increased incidence of blood clots/increased HCT

Eisenmenger Complex

• Complex results in R-L Shunt and major Complication is HPN
• Signs include increased resp, cough and diaphoresis

Acyanotic

  - Can interfere with normal flow by reducing and slowing blood flow

Non-obstructive issues include increased pulmonary flow Tetralogy Of Fallot: Pulmonary Stenosis , Ventricular Separation defect overriding Aorta and Increase RV Hypertrophy

Assessment Finding

• Audible VSD finding
• Frequent upper resp
• Tachycardia
• Enlargement of liver

Atrioventricular Canal

• Alterations depends on severity, which the pulmonary can increase
• R to Left shunt during blood, can also find CHF

Incomplete Valve

• Needs balloon stints or medication
• Needs assistance to work right

Cyanotic Heart defects

• Pulmonary not allowing adequate amount of blood and decreased breathing and or altered body requirements
• Infection chances increase and may impact a child not feeling safe due caregiver with poor health
• Reduced Assessment due to the child's understanding or even parent regarding the information given.

Types of surgery for both groups

• Closed heart procedure (no bypass)
• Open (bypass)

Palliative Operation

• Increase amount of blood flow and also prevent the amount of shunting which occurs
• Resection of the RV using punch tool to increase outflow

Nursing care

• Oxygen
• Monitor Oxygen Stat during Position: ACYANOTIC-ORTHOPNEIC POSITION CYANOTIC-SQUATTING/KNEE-CHEST POSITION TET increasing spasm but reducing blood floor decreasing the lungs .
• Happens when breathing , Stress.