Pediatric Cardiology: Heart Murmurs and PFO

Objectives for Pediatric Cardiology and Heart Murmurs

• Describe pediatric cardiovascular history and physical exams to differentiate acyanotic from cyanotic
• Identify the significance of left-to-right versus right-to-left shunts.
• Differentiate between innocent and pathological murmurs.
• Determine when to refer a patient to pediatric cardiology when evaluating a heart murmur.

The Transitional Heart

• Encompasses early embryonic and fetal development into neonatal life.

Maternal-Fetal Circulation

• Describes the circulatory system between a mother and fetus

Patent Foramen Ovale (PFO)

• PFO is a hole between the left and right atria in the heart's upper chambers.
• PFO exists in everyone before birth.
• PFO generally closes shortly after birth.
• PFO references a hole that fails to close naturally after birth.

Patent Ductus Arteriosus (PDA)

• PDA is an unclosed hole in the main body artery.
• The fetus does not need blood to go to the lungs, prior to birth, for oxygenation.
• After birth, the opening is no longer needed and typically narrows and closes within days.
• Failure of the ductus to close is common in premature infants, and rare in full term babies.
• A large PDA results in extra blood being pumped into the lung arteries, making the heart and lungs work harder and causing lung congestion.
• Indomethacin/Ibuprofen can be used in premature babies.
• Devices or suture ligation is necessary if spontaneous closure of a PDA does not occur.

Primary Care Evaluation of Pediatric Heart Murmurs

• The incidence of CHD in the general population is less than 1%.
• Less than 1% of new murmurs referred to a pediatric cardiologist are CHD-related.
• 40-45% of children have an innocent murmur at some point during childhood.
• 50-70% of examined individuals have a heart murmur.
• Evaluation tools include vitals, pulse oximetry, EKG (rate, rhythm, chamber thickness), chest X-ray (CXR), and echocardiogram.
• CXR is used to identify pulmonary flow and assess the heart, chest wall, diaphragms, and lungs for abnormalities.
• Echocardiograms are standard, noninvasive tools to evaluate heart structure.
• Cardiac catheterization is needed to obtain more precise anatomic information or hemodynamic function before making operating decisions.

Pertinent History

• Prenatal history of maternal infections, such as TORCH, can cause teratogenic effects.
• Prenatal ultrasounds can detect abnormalities associated with different syndromes or congenital heart defects (CHD).
• Fetal echocardiography plays an important role in prenatal diagnosis of CHD.
• Maternal history of medications, drug use, alcohol consumption, smoking, hypertension (HTN), or gestational diabetes mellitus (GDM) is relevant.
• A history of prematurity and low birth weight is important.
• Maternal or family history raising index of suspicion for CHD (Sudden Death in Young Relatives)

Key Symptoms in History (Red Flags)

• Poor feeding and poor growth
• Diaphoresis
• Respiratory difficulties
• Excessive irritability
• Exercise intolerance
• Syncope with exercise
• Chest pain with exercise

Physical Examination

• Includes inspection for growth, nutrition, circulation, respiratory effort, cyanosis, chest asymmetry, precordium, and dysmorphic features.
• Palpation of pulses in all 4 extremities for weakness, bounding, or clubbing cyanosis, and checking abdomen for hepatomegaly is critical.
• Auscultation is essential, supplementing inspection and palpation and should be performed in supine and upright positions.
• Vitals include temperature, heart rate, respiratory rate, blood pressure, and O2 saturation.

Heart Sounds

• S1 is associated with the closure of the mitral and tricuspid valves and is best heard at the lower left sternal border or apex.
• S2 is associated with closure of the aortic and pulmonic valves and is considered a valuable portion of the cardiovascular exam.
• Clicks are extra heart sounds that represent underlying valvar pathology.
• Murmurs with a vibratory or musical quality, grade I-II intensity, located at the left sternal border, short in duration, or midsystolic are typically benign or innocent in nature.

Heart Murmurs

• These are sounds such as whooshing or swishing made by rapid, choppy blood flow through defects in the heart.
• Any change in viscosity may alter turbulent flow.
• Higher pressure gradients across a narrow area (valve, vessel, defect) result in faster flow and a higher frequency murmur.
• Low-frequency murmurs imply low pressure gradients and mild obstruction.

Causes of Heart Murmurs

• Increased flow across normal structures.
• Obstructed flow across abnormal structures.
• Regurgitant flow across incompetent valves.
• Turbulent blood flow from one chamber/vessel into another (shunts).

Right to Left Shunt

• Occurs when right atrial pressure exceeds left atrial pressure.
• Allows deoxygenated systemic venous return to bypass the lungs, and return to the body without becoming oxygenated.
• Results in cyanosis at birth, which, if severe, can result in perinatal death unless surgically corrected.

Left to Right Shunt

• Characterized by a "back leak" of blood from systemic to pulmonary circulation, leading to larger pulmonary flow compared to systemic flow.
• High blood volume or pressure causes a significant shunt and progressive damage to the pulmonary vasculature and pulmonary hypertension.

Acyanotic Heart Lesions

• Acyanotic lesions generally result in a change in volume load from systemic to pulmonary circulation.
• Ventricular Septal Defect (VSD) is the most common heart lesion in children.
• Small VSDs can be asymptomatic, harsh, LLSB, and holosystolic.
• Large VSDs may be less harsh but cause dyspnea, feeding difficulties, reduced growth and profuse sweating, leading to complications like heart failure.
• Small VSDs close by 6-12 months; Trisomy 21 increases the risk for this lesion.
• Acyanotic lesions include PDA, ASD, and Atrioventricular Septal Defects.
• ASDs are often asymptomatic but can lead to pulmonary HTN or atrial arrhythmias due to atrial enlargement.
• AV Septal defect/AV canal consists of atrial/ventricular septal defects and abnormal AV valves, requiring correction in infancy.

Innocent Murmurs

• Still's Murmur is most common in children aged 2-8 years, grade 1-3/6, musical/vibratory, LLSB, louder in supine position, and reduced with Valsalva.
• Venous Hum is common in children aged 2-5 years, grade 1-3/6, soft continuous, RUSB/Infraclavicular area, heard while sitting, disappearing when laying or with neck extension.
• Peripheral Pulmonic Stenosis is common in newborns to 6 month olds, grade 1-3/6, RUSB radiating to axilla and back, turbulent flow across pulmonary arteries, and disappears by 6 months.
• Pulmonary and Aortic Flow Murmurs can occur at any age, grade 1-2/6, heard best at LUSB/RUSB, often a result of high output states like fever, dehydration, or anemia; Stenotic murmurs are harsher and may have an ejection click and should be seen as follow-up after resolution of ill symptoms.

Cyanotic Lesions (CCHD)

• Peripheral cyanosis is common in neonates, typically affecting the extremities, and can be normal.
• Central cyanosis is always abnormal and is seen on the tongue, gingiva, and buccal mucosa.
• Ductus-dependent lesions are cardiac defects that are incompatible with life without a PDA.
• Right-to-left shunts involve abnormal blood flow across a cardiac defect from the right heart containing deoxygenated blood that is then pumped to systemic circulation, resulting in cyanosis.

Cyanotic Congenital Heart Disease (CCHD)

• Heart defects that cause a right to left shunt are cyanotic heart disease.
• There are five types to remember.
• One great vessel leaving the heart: Truncus Arteriosus.
• Two great vessels transposed: Transposition of the Great Arteries (TGA).
• Tri(3)cuspid fails to form: Tricuspid Atresia.
• Tetrad(4) cardiac defects: Tetralogy of Fallot (TOF).
• Five words: Total Anomalous Pulmonary Venous Return (TAPVR).

Cyanotic CHD Manifestation

• Cyanotic CHD often manifests after the PDA begins to close.
• PDA closure occurs on the first or second day of life.
• Prostaglandin E1 keeps the ductus open and allows for infant stabilization before definitive correction.
• Cyanotic CHD is characterized by decreased pulmonary flow.
• Occurs in Pulmonary Valve Stenosis or when the origins of the pulmonary artery and aorta are switched (TGA).
• Transposition of the great arteries occurs in 5% of children with CHD.
• Transposition of the great arteries is the most common cause of cyanosis in neonates.
• Chest X-ray (CXR) shows an "egg on a string” appearance.
• Pulmonary stenosis with a large VSD results in Tetralogy of Fallot (TOF).
• CXR shows a boot-shaped appearance.
• Many kids have Hypercyanotic spells (Tet spells), with agitation or activity.
• Cyanosis is a hallmark of kids who have Tricuspid valve abnormalities of tricuspid atresia or Ebstein anomaly.
• The tricuspid valve of Ebstein anomaly is insufficient.
• Cyanosis leads to two valves displaced inferiorly, into the right ventricle, and both conditions are ductal-dependent in neonates, requiring surgical correction.

Critical Congenital Heart Defects Screening (CCHD)

• A pulse oximeter is used to measure the percentage of hemoglobin in the blood that is saturated with oxygen (preductal and postductal).
• Screening can identify Critical CHD that present with hypoxemia and many other non-cardiac conditions.
• Including hypothermia, sepsis, lung disease, or hemoglobinopathy.
• Any oxygen saturation <90% (Initial Screen) results in failed screen.
• Oxygen Saturation < 95 % in the right hand, and foot on 3 measures, separated by 1 hour results in failed screen.
• An absolute difference in oxygen saturation >3% between the right hand and foot on 3 measures, each separated by 1 hour results in failed screen.

Quiz Answers

• 13 year old boy brought to your office for ACV/sick visit: Refer to Cardiology. PMH unremarkable. PE -temp 103.F, Breathing unlabored ,HR 110 , no nuchal rigidity , pharynx injected, no tonsillar exudates . PA notes grade II/VI systolic murmur along LSB with no radiation to back. No Abdominal tenderness or organomegaly.
• 2 year old with no significant medical history: Venous Hum. Growing normally and gaining weight appropriately. Normal developmental milestones. Normal exam and vitals signs. On PE, low pitched , soft (grade I-II) ,continuous murmur heard in infraclavicular region while sitting down. Disappears when lying down or when you apply pressure to veins of neck with the head turned to the side.
• 18 month old with a stable but moderate size VSD presents to the Peds Dentist: None of the above.
• 15 month old playing in the waiting room: Boot shaped heart
• A previously healthy term infant suddenly develops respiratory distress: Prostaglandin therapy
• You are called to Newborn nursery to evaluate 2 day old girl with: Trisomy 21 with VSD