Congenital Heart Disease: Clinical Perspectives

Some general information about Congenital Heart Disease

• Most common human congenital malformation
• There are 8 in 1,000 live births (doesn’t include minor defects)
  • Ventricular Septal Defect is the most common—25% of all Congenital Heart Disease
  • Atrial Septal Defect, Pulmonic Stenosis , coarctation, Tetrology of Fallot  10% each
  • Patent Ductus Arteriosus, Aortic Stenosis , Transposition of the great arteries  5% each
  • Hypoplastic Left Heart , trubcus arteriosus, Total anomalous pulmonary venous return  1% each
• There is a much higher incidence of these Congenital Heart Disease in stillborns and spontaneous abortions
• Hypoplastic Left Heart is very rare but it is mentioned here because it is the most common cause of death due to a Congenital Heart Disease
• The baby’s siblings and future children have a much greater chance of having any of these diseases

Etiology of Congenital Heart Disease

• Only about 10% of Congenital Heart Disease has a known cause
• 3% is classic Mendelian mutant genes
• 3% is chromosomal abnormalities (Down’s Syndrome)
• 3% environmental factors (which include drugs, maternal illness such as diabetes, toxins like alcohol and viral infections such as rubella and coxsackie)
• Most are multifactorial
• Here she gave some pictures and talked about various syndromes (I don’t have the pictures but I’ll list the syndromes)
• Down’s Syndrome-about 50% of Down’s syndrome patients will have a Congenital Heart Disease and 1 in 5 will have a severe defect called an AV canal where there are septal defects between all the chambers of the heart.  Basically, all of the chambers are able to communicate with one another (the recording is fuzzy here but I think that’s what it’s called).
• Turner’s Syndrome:  these babies will have a webbed neck, low hairline and widely spaced nipples.  These babies have a high incidence of coarctation of the aorta
• William’s Syndrome:  characterized by hypercalcemia: the child will have aortic stenosis
• Fetal alcohol syndrome:  the baby will usually have a Ventricular Septal Defect

Some pathophysiology of Congenital Heart Disease
 

1. Even serious Congenital Heart Disease can be compatible with intrauterine life because the blood is being oxygenated by the mother
2. The ductus arteriosus begins to close 12-15 hours after birth and continues to close for a couple of weeks afterwards.  The things that initiate the closing are a sudden increase in arterial oxygen saturation (it’s not as high in utero) and the disappearance of placental prostaglandins which help maintain the ductus before birth.  Sometimes the ductus arteriosus will mask an underlying Congenital Heart Disease, the child will be fine at discharge and a week later will present with a serious Congenital Heart Disease.
3. Pulmonary vascular resistance also drastically increases after birth which becomes important when there is a defect that would cause a left to right shunt.  As the pressure differential increases, the blood will flow from left to right that’s when the child will present (could be up to 6-8 weeks after birth).
    

There are two categories of Congenital Heart Disease

 Acyanotic Congenital Heart Disease

• Large left to right shunts: a, Atrial Septal Defect and Patent Ductus Arteriosus.  The amount of shunting will depend on the size of the communication, the pressure difference between the chambers and the total outflow resistance
• Obstructive lesions: Aortic Stenosis, Pulmonic Stenosis, coarctation and Hypoplastic Left Heart
• Babies can present with congestive heart failure:  this occurs for two reasons, either there is too much flow (as in the shunts) or there is an obstruction to flow (obstructive lesions).  The heart has to pump harder causing hypertrophy and eventually Congestive Heart Failure.

Cyanotic Congenital Heart Disease

• Cyanosis is a feature (no crap)
• These are the 5 T’s
  • Tetrology of Fallot
  • Transposition of the great arteries
  • Tricuspid atresia (no tricuspid valve and hypoplasia of the right ventricle)
  • Total anomalous pulmonary venous return (pulmonary veins don’t dump into left atrium, they find an alternate route and can enter the RA or dip below the diaphragm and enter the IVC)
  • Truncus arteriosus (no separation between the pulmonary artery and aorta)

Congestive Heart Failure

• There are three pathophysiologic causes (the three things that contribute to cardiac output)
  • Decreased myocardial contractility (such as in myocarditis)
  • Increased afterload (increased pressure) which occur in the obstructive lesions (a lot of blood still left after contraction)
  • Increased preload (increased volume) which occurs in shunting conditions (a lot of blood to begin with)
• There are different ages for presentation.  If it is an afterload problem it will present in the first 2 to 3 weeks of life (could be within the first 24 hours).  If it is a preload problem it will present around 2 months when the pulmonary vascular resistance is the lowest and there is the most amount of shunting.  Contractility problems can present at any age.
• Volume overload is the most common cause of Congestive Heart Failure in children.
• History:
  • There will be symptoms of exertional dyspnea which is age dependent (you will see it manifest in babies as difficulty eating and crying and in older children as fatigue during activity)
  • Infancy:
    • Poor feeding (usually a change in feeding habits, used to be able to eat more and used to take much less time)
    • Diaphoresis (sweating) with crying
    • Growth failure which is the primary indicator
  • Older children look more like adults with regard to Congestive Heart Failure
    • Easy fatigability (tired after chasing the dog around)
    • Shortness of breath
    • Edema
• Physical exam
  • There is a classic triad in infancy: tachypnea first (normal is 40), tachycardia (normal is 140bpm, Congestive Heart Failure will cause it to go up to 180-200 bpm) and hepatomegaly (firm, blunt and tender and can go all the way to the pelvis)
  • Displaced PMI (moves laterally due to cardiomegaly)
  • Cool moist extremities and prolonged capillary refill due to cardiogenic shock
  • Wheezing due to left ventricular failure
  • Abnormal upper extremity vs lower extremity blood pressure (UE should be lower).  Always use the right upper arm
  • There can be murmurs with the intensity of the sound inversely proportional to the size of the shunt
    • Holosystolic (throughout all of systole) murmur that’s harsh at the LLSB is a Ventricular Septal Defect
    • Ejection systolic (crescendo-decrescendo) at ULSB is an Atrial Septal Defect or Pulmonic stenosis
    • Ejection systolic at URSB is aortic stenosis
    • Continuous, machine-like and L infraclavicular is a Patent Ductus Arteriosus
    • Short systolic, soft and the L interscapular (on the back) is mild to moderate coarctation
  • You don’t have to have a murmur to have a severe defect like severe coarctation or Hypoplastic Left Heart syndrome
  • Normal heart sounds include an S2 split on inspiration so you want to hear this.  With a lot of defects there is always an S2 split regardless of inspiration or expiration because there is a continuous flow of blood.
• Diagnostic evaluation
  • Chest X ray: looking for cardiomegaly and increased pulmonary markings (except with Pulmonic Stenosis, you will get decreased pulmonary markings)  the cardiothymic profile should be less than 2/3 the total thoracic diameter
  • EKG:  looking for RVH, LVH and BVH
  • Echo:  usually the best diagnostic tool
  • Cardiac MRI which can only be used in children and adolescents
  • Cardiac catheratization/angiography:  only used to detect rare deformities (can be used to look at oxygen saturation and pressures in the different chambers)
• Treatment
  • Mainstay of treatment is to rest the heart, oxygen, sodium restriction (to decrease preload), fluid restriction, digoxin, furosamide (diuretic)
  • If it is a Ventricular Septal Defect:  use medical treatment for one year (about 35% will spontaneously close) and frequent follow-ups to assess PVR.  There will be surgical intervention in one year if the hole hasn’t closed (sooner if there is also pulmonary hypertension) to prevent Eisenmenger’s syndrome (when there has been a reversal in the shunt and the blood is now moving from right to left resulting in cyanosis, the only treatment for this is a heart transplant) This is the most common Congenital Heart Disease so we should know this treatment
  • Atrial Septal Defect and Patent Ductus Arteriosus:  cath lab closure or surgery if that doesn’t work
  • Aortic and pulmonic stenosis:  cath lab balloon valvuplasty or surgery if that doesn’t work
  • Coarctation:  Prostaglandin E1 to keep the ductus arteriosus open and early surgery (especially in newborns with severe coarctation)
  • Hypoplastic Left Heart syndrome:  Prostaglandin E1 and a 3 stage surgery (limited success)
  • Again, cardiac catheterization can be done through the femoral vein or artery to obtain stats and do angiography

Cyanosis-bluish purplish tinge

• This can be difficult because there can be a significant right to left shunt without any evidence of cyanosis—it depends on the hemoglobin levels
• It is visible when there is a 5g/dL reduction in hemoglobin.  For example in newborns there is 20 g/dL hemoglobin so you would only need a 25% reduction in Hb to see cyanosis.  Children at 2 months are anemic with a Hb level of 10 g/dL, so they would need a 50% reduction in their hemoglobin to see cyanosis.
• There are two types of cyanosis.  Peripheral which has a normal pO2 and spares the mucosa and central which has a decreased pO2 and involves the mucosa (not really worried about peripheral cyanosis which can happen in anyone—like in very cold temperatures)
• Cyanosis may be subtle so it’s important to look for clubbing (this is where you put you thumbs together and it should form a diamond…go on and try it, you know you want to).

History of Cyanotic Congenital Heart Disease

• Newborn cyanosis:  can be Transposition of the Great Arteries, severe Pulmonic stenosis, tricuspid atresia, truncus arteriosus, Total Anomalous Pulmonary Venous Return
• Cyanosis in infancy or childhood:  can be Tetrology of Fallot, Total Anomalous Pulmonary Venous Return
• Episodic agitation, inconsolable crying, acutely deepening cyanosis and squatting:  called hypoxic or “Tet” spells and are due to Tetrology of Fallot (don’t know you have a problem until you do something that will decrease your afterload)
• Symptoms of Congestive Heart Failure:  due to truncus arteriosus

Physical Exam

• Tachypnea
• Central cyanosis
• Clubbing
• Single S2 (most) or widely split S2 (some Pulmonic Stenosis and Total Anomalous Pulmonary Venous Return)
• Murmur
  • Ejection systolic at ULSB:  Tetrology of Fallot and Pulmonic Stenosis
  • Holosystolic and harsh at LLSB:  Truncus (Ventricular Septal Defect)
  • Or no murmur at all:  Transposition of the Great Arteries and tricuspid atresia

Diagnostic Evaluation

• Chest X ray:
  • Boot shaped heart is a Tetrology of Fallot due to right ventricular hypertrophy
  • Egg on a string:  Transposition of the Great Arteries (the string is a narrowed mediastinum)
  • Pulmonary blood flow is increased in Transposition of the Great Arteries, truncus and Total Anomalous Pulmonary Venous Return and is decreased in Tetrology of Fallot, pulmonic stenosis and tricuspid atresia
• EKG: 
  • Right ventricular hypertrophy in Tetrology of Fallot, Transposition of the Great Arteries, pulmonic stenosis, Total Anomalous Pulmonary Venous Return
  • Left ventricular hypertrophy in tricuspid atresia due to hypoplastic right ventricle
  • Biventricular hypertrophy in truncus arteriosus ( both ventricles are pumping harder into one vessel)
• Echo

Treatment

• Tetrology of Fallot:  complete surgical repair in infancy.  If it is too complex, there is a palliative shunt from subclavian to pulmonary artery and repair is done later
• Transposition of the Great Arteries:  prostaglandin E1 given to maintain ductus arteriosus, balloon atrial septostomy (tear a big hole in the atria to get mixing of blood) and complete repair (arterial switch) within first two weeks of life

Extracardiac Complications of Congenital Heart Disease

Two sample cases: 

1. 2 and a half year old girl becomes tachypnic and cyanotic.  There is a murmur at then ULSB.  Diagnosis:  Tetrology of Fallot that went undiagnosed because it wasn’t until now that the pressure was great enough to cause the right to left shunt.
2. 2 month old baby that won’t feed well recently.  HR 170, RR50, liver below umbilicus, murmur with thrill that is holosystolic and harsh.  Diagnosis is Ventricular Septal Defect.  On a chest x-ray you will see a huge heart.  If patient does not do follow up care, what is the associated condition?  Eisenmenger’s syndrome where the shunt has now switched to right to left.  The only treatment now is a heart transplant.

Back to the Circulatory System Index