Pediatrics: Congenital Heart Disease

• Pediatrics Congenital Heart Disease covers the physiology of circulation from intra-uterine life to extra-uterine life and describes some congenital heart defects.

Extra-Uterine Life Circulation

• Blood flows from the right atrium to the right ventricle, up to the aorta, then to the lungs, to the left atrium and left ventricle

Intra-Uterine Life Circulation

• Includes circulation between the placenta, umbilical vein and artery of the fetus

Placenta

• Organ that develops in the uterus during pregnancy, providing oxygen and nutrients to the growing baby, and removing waste products from the baby's blood.
• Six main functions: respiration, nutrition, excretion, protection, endocrine and immunity. IgG assists with immunity

Foramen Ovale (PFO)

• A small hole in the septum between the two upper chambers of the heart, or atria
• Before a baby is born, they do not use their lungs to get oxygen

Ductus Arteriosus (PDA)

• A blood vessel in the developing fetus that connects the trunk of the pulmonary artery to the proximal descending aorta.
• Allows most of the blood from the right ventricle to bypass the fetus's fluid-filled, non-functioning lungs

Ductus Venosus (PDV)

• A shunt that allows oxygenated blood in the umbilical vein to bypass the liver
• It is essential for normal fetal circulation
• Blood becomes oxygenated in the placenta then travels to the right atrium via umbilical veins through the ductus venosus then to the inferior vena cava

Introduction to Congenital Heart Disease (CHD)

• CHD is the most common congenital disorder in newborns
• A defect in the structure or function of the heart and great vessels present at birth
• It is not static, but always has a continuous anatomical or physiological change

Epidemiology and Genetic Basis of CHD

• Congenital heart disease occurs in approximately 0.8% of live births
• The incidence is higher in stillborns (3-4%), spontaneous abortuses (10-25%), and premature infants
• In preterm infants, CHD is two to three times that in term infants
• Approximately 2-3 in 1,000 newborn infants will be symptomatic with heart disease in the 1st year of life
• With advances in both palliative and corrective surgery, there are increased survival rates
• Despite these advances, CHD remains the leading cause of death in children with congenital malformations

Etiology of CHD

• Etiology is often unknown
• It can be multifactorial, resulting from a combination of genetic predisposition and environmental factors
• It can be related to chromosomal abnormalities like Trisomy and Turner syndrome.
• Additional risk factors include a third pregnancy (multiparity) 20-30%
• The risk of recurrence of CHD increases if a 1st-degree relative, such as a parent or sibling, is affected
• 2-4 % environmental/ adverse maternal conditions and tetratolgic influence
• GDM
• Phynelketonuria
• SLE
• Congenital rubella syndrome
• Maternal ingestion of drugs is contraindicated during pregnancy, especially catergory X

Gender Differences in Specific Cardiac Lesions

• Transposition of the great arteries and left-sided obstructive lesions are slightly more common in boys at approximately 65%
• Atrial septal defect, VSD, PDA, and pulmonic stenosis are more common in girls

Recognition of Cyanosis

• Cyanosis is a blue color of skin and mucous membranes caused by reduced oxygen content
• Oxygen content of blood depends:
  • Hgb level
  • Oxygen saturation
  • Blood flow
• Cyanosis noted when Sat's <86%, but it is more difficult to see in anemia

Central Cyanosis

• Noted in the trunk, tongue, mucous membranes, and due to reduced oxygen saturation

Peripheral Cyanosis (Acrocyanosis)

• Noted in the hands and feet, around mouth, due to reduced local blood flow

Classification of Congenital Heart Disease

• Categorized as acyanotic or cyanotic, with further subcategories based on pulmonary blood flow and obstruction to blood flow.
• Acyanotic: Increased pulmonary blood flow includes atrial septal defect, ventricular septal defect, patent ductus arteriosus, atrioventricular canal
• Obstruction to blood flow from ventricles includes coarctation of aorta, aortic stenosis, pulmonic stenosis
• Cyanotic: Decreased pulmonary blood flow includes tetralogy of Fallot, tricuspid atresia
  • Mixed blood flow includes transposition of great arteries, total anomalous pulmonary venous return, truncus arteriosus, hypoplastic left heart syndrome

Patent Ductus Arteriosus (PDA)

• PDA is the persistence of the normal fetal vessel that joins the pulmonary artery to the aorta
• It normally closes in the 1-2 week of life
• There is a Female:Male ratio of 2:1
• It is associated with maternal rubella infection during earlv pregnancy
• PDA is a common problem in premature infants
• The direction and magnitude of the shunt across such a communication depends on the size of the defect
• Fluid leak into the interstitial space and alveoli = Pulmonay Edema
• Symptoms and signs * tachypnea, * chest retractions, * nasal flaring, * wheezing

Pathophysiology of PDA

• Resulting from the higher aortic pressure postnatally, blood shunts left to right through the ductus from the aorta to the pulmonary artery.
• The extent of the shunt depends on the size of the ductus and on the ratio of pulmonary to systemic vascular resistance
• If the PDA is small, pressures within the pulmonary artery, the right ventricle, and the right atrium are normal
• If the PDA is large, pulmonary artery pressure may be elevated to systemic levels during both systole and diastole
• Small PDA is usually asymptomatic
• Other manifestations include tachycardia, shortness of breath, retardation of physical growth
• A characteristic systolic-diastolic murmur at the base of the heart with maximum in the PA
• Chest X-ray show an increased pulmonary vascularity and enlargement of left sided heart

Therapeutic Interventions for PDA Closure

• Pharmacologic therapy is used exclusively in premature infants
• Surgical ligation
• Percutaneous catheter occlusion.
• Mortality is < 1%
• Indomethacin (Inhibitors of prostaglandin synthesis) is used as the initial intervention for PDA closure in preterm infants
• Ibuprofen is effective in closing a PDA and currently appears to be the drug of choice, and reduces the risk of Necrotizing Enterocolitis (NEC) and transient renal insufficiency
• Paracetamol is effective in closure of PDA in preterm neonates and has less side effects mainly on renal function, platelet count, and GIT bleeding
• Indomethacin -0.2 mg/kg
  • Ibuprofen -10-5-5 mg/kg
• The surgical approach and technique is dependent up on the size and age of the patient
• Following surgery complication include recurrent laryngeal nerve paralysis, respiratory compromise, infection and intracranial hemorrhage in preterm infants
• Percutaneous closure provides an alternative to surgical ligation in patients beyond infancy using catheter
• Access is generally achieved through the femoral artery or vein
• Closure of the PDA with coil or device without thoracotomy

Indications for PDA Closure

• Symtomatic
• Left cardiac overload (left atrial or venticulat enlargement)
• Mild to moderate Pulmonary Arterial HPN (PAH)
• Previous episodes of endocartitis

Atrial Septal Defect (ASD)

• An opening in the atrial septum permitting free communication of blood between the RA and LA
• ASDs can occur in any portion of the atrial septum, depending on which embrvonic septal structure has failed to develop normally
• Three major types: Secundum, Primum, Sinus Ve no sus

Secundum ASD

• Secundum ASD is at the Fossa Ovalis and accounts for 70 to 75 percent of all ASDs
• Most common

Primum ASD

• Lower in position and accounts for 15 to 20 percent of ASDs

Sinus Venosus ASD

• High in the atrial septum and the least common

Atrial Septal Defect (cont.)

• In normal hearts, the chambers of the left side of the heart are at a higher pressure than those on the right side.
• In a large ASD (>9mm), a left-to-right shunt occurs, with blood flowing from the LA to the RA.
• This extra blood may cause a volume overload of both the right atrium and the right ventricle
• The RV must push out more blood than the LV due to the L-to-R shunt
• This condition can result in eventual RV-failure (dilatation and decreased systolic function) and Pulmonary HPN
• When the pressure in the RA rises to the level in the LA, the left-to-right shunt diminishes or ceases
• When the pressure in the RA is higher than the pressure in the LA and will reverse the shunt → right-to-left shunt will exist (this phenomenon is known as Eisenmenger's syndrome)
• Most infants with ASDs are asymptomatic
• They may present at 6 to 8 weeks of age with a soft systolic ejection murmur
• Other clinical signs found in infants are a hyperactive precordium, RV heave, fixed widely split S2 and Mid-diastolic murmur heard over LLSB.
• Children with large left-to-right shunts are likely to complain of some fatigue and dyspnea.
• Growth failure is very uncommon
• Most are asymptomatic, but may have easy fatigability or mild growth failure
• Cyanosis does not occur unless pulmonary HPN is present.

Radiologic Features of ASD

• RV is enlarged, defect is visualized with an Echo-CG
• The heart is usually enlarged, with a cardiothoracic ratio >0.5
• Pulmonary vascularity is increased with a chest X-ray

Natural History of ASD

• Secundum ASDs can close spontaneously, remain unchanged, or enlarge
• Spontaneous closure, or a decrease in size, is most likely to occur in defects less than 7 to 8 mm in diameter and with younger age at diagnosis

Treatment for ASD

• The treatment for isolated secundum ASD is closure of the defect, which can be achieved by a surgical or percutaneous transcatheter approach
• The majority of isolated secundum ASDs <6 mm diameter in infants close spontaneously by 2 years, and some as late as 5 years of age.
• Defects of moderate size (at least 6 to 8 mm in diameter) and larger are relatively unlikely to close spontaneously.
• Clinical standard to repair via surgical catherization closure for secundum ASD
• Surgical correction is done earlier in children with CHF or significant Pulmonary HPN.
• Prophylactic antibiotics are recommended during the first six months after the repair.

Peripheral Acyanosis Treatment

• PDA - failure of the DA to close
  • Pharmacology (Ibuprofen) or SURGERY (ligation): Determined by Age, Heart viability and if evident symptoms (CO and Cardiac Infection) are detected
• ASD - opening of the septum between RA and LA, dependent on the location of the opening - SURGERY (ligation or PC) and antibiotic treatment is given straight 6 months after repair with Pul. HPN and with certain age and size of defect/opening

Ventricular Septal Defect

• VSD is abnormal opening in the ventricular eptum, which allows free communication between the R and L ventricles.
• In 25% of all CHD, the most common CHD in infants occurs

Ventricular Septal Defect (cont.)

• Shifting of blood from LV to RV due to a leak = increases supply to RV = increases supply to lungs, causing PULMONARY HPN
• Common signs and symptoms include fatigue, SOB, difficulty feeding, poor growth (1st week of life)
• Increase pressure of RV may be used to shift back to supply to LV (decrease concentration of oxygenation) = CYANOSIS.
• https://www.youtube.com/watch?v=1rH-IcKukiM

Types of Ventricular Septal Defect

• Perimembranous (or membranous) – Most common at 80%
  • Defect lies in the outflow tract of the left ventricle immediately beneath the Aortic Valve (AV)
• Muscular VSD
  • Defects in the muscular septum are frequently multiple and make up 5% to 20% of defects
  • Infundibular (subpulmonary VSD)
  • Defect involves the RV outflow tract and are in the outflow tract of the right ventricle beneath the pulmonary valve
• AVSD
  • Posterior and inferior to the membranous defect, beneath the septal leaflet of the tricuspid valve almost always involves AV valvular abnormalities
• Small defects are usually asymptomatic and 50% will close spontaneously by age 2yrs -Moderate – large VSD often have symptoms
  • Surgical repair is required before 1st year
• Other symptoms include heart murmur, fatigue, SOB, difficulty feeding, poor growth (1st week of life) -CYANOSIS (RV compensation)

Chest X-ray for Ventricular Septal Defect

• Increased pulmonary vascularity
• Enlargement of the LA and LV
• Cardiomegaly

Diagnosis of Ventricular Septal Defect

• Confirmatory diagnosis is by Echocardiogram
• Test that uses sound waves (ultrasound) to create images of the heart
• Doppler test uses sound waves to measure the speed and direction of blood flow

Treatment Medical Therapy for Ventricular Septal Defect

• Children with small VSDs are asymptomatic and have excellent long-term prognosis with neither medical therapy nor surgery indicated
• Bacterial endocarditis prophylaxis will be indicated -If children with moderate or large VSDs develop symptomatic trial medical therapy -Furosemide -Enalapril (Vasotec) is with 0.1mg initial dosage and increase gradually maximum of 40 mg/day

Surgical Closure for Ventricular Septal Defect

• Large VSD w/ medically uncontrolled symptomatology & continued FTT(failure to thrive) Ages 6-12 months with Pulmonary HPN -Secondary risk of developing Ateroventricular insufficiency

Acyanotic Congenital Heart Disease: Obstruction to Blood flow

• Includes:
  • Coarctation of the Aorta
  • Pulmonary Stenosis
  • Aortic Stenosis

Coarctation of the Aorta

• A narrowing of the descending aorta
• Occurs in 6-8% of CHD cases
• More common in males than females
• Is largely genetic
• Turner Syndrome has an occurance rate of 35%

Pathogenesis and Etiology

• Congenital causes have two main theories for the development of the coarctation of aorta is reduced antegrade intrauterine blood flow causing underdevelopment of the fetal aortic arch along where migration or extension of ductal tissue into the wall of the fetal thoracic aorta
• There is also increasing vascular wall defect in the ascending aorta of individuals with congenital coarctation of aorta Acquired due to aortic narrowing from abnormal inflammatory diseases of the aorta, such as severe atherosclerosis

Coarctation of the Aorta (cont.)

• It causes of obstruction of left ventricular outflow with LV afterload increases pressure hypertrophy of the LV.

Clinical Signs and Symptoms of Aortic Coarctation

• Classic signs of coarctation are:
  • Decreased or absence of femoral pulses -Increased BP (discrepancy of upper vs lower, rt vs lt arms)

Treatment of Coarctation of the Aorta

• Management decisions for patients with coarctation of the aorta depend upon patient age, presentation, and the severity of the lesion.
• Critical coarctation in infancy: Infants with severe("critical") coarctation are at-risk for developing heart failure and death when the ductus arteriosus closes -Identification of these patients is essential in order to maintain patency of the ductus prior to surgical repair -Immediate treatment is required to stabilize patients with Heart failure
• Surgical Repair is with Resection with end-to-end anastomosis -Subclavian flap aortoplasty used in infants with long-segment coarctation Bypass graft is used across when the area coarctation is too long for an end-to-end repair -Prosthetic patch (Aortoplasty) is avoided whenever possible because of the frequent occurrence of aortic aneurysm or rupture

Ballon Angioplasty

• Non-invasive alternative to surgical repair for older infant (>4mons.)
• Preferred intervention for all patient with isolated recoarctation regarless of age.

Pulmonary Stenosis

• Involves narrowing or obstruction between the RV to the PA
• Accounts for 7-10% of all CHD
• In most cases are isolated lesions
• Can be present w/ or w/o an intact ventricular septum
• May be biscuspid or fusion of 2

Pulmonary Stenosis Hemodynamics

• RV pressure causes hypertrophy and eventually RV failure.
• RV pressures may be > systemic pressure.
• Post-stenotic dilation of main PA.
• With intact septum & severe stenosis, can lead to R-L shunt through PFO
• Cyanosis may be indicative of Critical PS. https://www.youtube.com/watch?v=Riorbxccxt0

Clinical Signs and Symptoms of Pulmonary Stenosis

• Asymptomatic in most patients with valvar pulmonary stenosis if with mild PS < 30mmHg -Dependent on the severity of obstruction -Mod-severe: 30-60mmHg, > 60mmHg with Prominent jugular or Heart failure & cyanosis seen in severe cases

Treatment of Stenosis

• Mild PS requires no intervention and is followed up closely
• Mod-severe stenosis may require relieve via Ballon valvuloplasty for treatment
• Surgical valvotomy is also a consideration

Aortic Stenosis

• Difficulty/failure to open of the AV from LV
• Occurs in 7% of CHD cases
• More dangerous lesion compared to PS

Types of Aortic Stenosis

• Valvular is the most common type
• Subvalvular (subaortic)involves the left outflow tract
• Supravalvular involves the ascending aorta and is least common

Clinical Signs and Symptoms of Aortic Stenosis

• Mild AS may present with exercise intolerance or easy fatigability, but usually asymptomatic.
• Symptoms of Moderate AS are chest pain, dyspnea on exertion, dizziness & syncope. -Symptoms of Severe AS are weak pulses, left sided heart failure with Sudden Death
• Diagnosis is through the following with Echocardiogram https://www.youtube.com/watch?v=EJLck30rkCY

Treatment for Damaged Valve

Surgical Repair involves: • balloon valvoplasty and removal of excess tissue with Stenosis will recur

Surgical Valve Replacement is with: Mechanical options including: a last longer with life-long anticoagulant Bioprosthetic options

Cyanotic Congenital Heart Disease

• Causes cyanosis when obstruction to right ventricular outflow causes intracardiac right-to-left shunting with Complex anatomic defects

• An admixture of pulmonary and systemic venous return in the heart with a Decreased pulmonary blood flow and Chest X-Ray shows decreased pulmonary vascular markings

Tetralogy of Fallot

Most common cyanotic heart disease. It causes a blue baby and some of the four abnormalities it Includes:

1. Pulmonary stenosis
2. RVH
3. VSD
4. Overriding Aorta (See also https://www.youtube.com/watch?v=8BJOUfycsxo)

Pathophysiology:

Increased resistance by the pulmonary stenosis causes deoxygenated systemic venous return to be diverted from RV, through VSD to the overriding aorta and systemic circulation causing systemic hypoxemia and cyanosis

Clinical Signs and Symptoms

• Symptoms are variable depeanding on the degree of obstruction and if Cyanosis • There is * Tet spells(Hypercyanotic ): irritability, cyanosis, hyperventilation and at Cerebral Hypoxemia will * Mental retardation and Retarded growth and development with * RV heave or have is *Systolic ejection murmur

• A variableCyanosis - in the 1st yr of life due toSevere dyspnea o

Chest X-Ray Show

• A decreased pulmonary vascular marking or with *"Boot-shaped heart" -Temporary Shunt and Temporary Repair with Pulmonary

Temporary Treatment for TOA

• Temporary Shunt = aorta to the RPA
• Stent with PA increasing arterial lungs for the Temporary Repair with pulmonary stenosis through an aorta for the the lungs
• *VSD to the for the excess aorta to and or in ‡ valve

Complete Repair

• Stenosis to and artery covering

— Over aorta to

Transposition of the Great Arteries

Is classified mixed blood flow or with and is a normal UnO2

• RV = Pa 02 with PV = LA = LV =

— TGA—UnO2 aorta lungs aorta Bp8k8

• RA LA and aorta. The signs include cyanosis is https://www.youtube.com

Clinical Manifestation

— that, and and open Nonspecific a present, may - * Murmursmidleft

Treatment

• 1st arterial the aorta arterial location at