Sketched - Pediatric Heart Defects by Courtney Graham

Note from Tyler: Courtney and I were chatting the other day about the fact that both of us had, at one point, a goal to work as  animation artists at Disney. The longer I have known Courtney the more I realize how gifted she is to bring science and art together so flawlessly. I asked her to illustrate some of the pediatric heart defects in an artistic and yet easily digestible format. Courtney did exactly that! In this blog you will find the major pediatric heart defects beautifully illustrated. I hope you enjoy the amount of work and heart she put into this.

Cardiology - (noun) – the branch of medicine that deals with diseases and abnormalities of the heart. AKA, some clinicians least favorite topic, especially when it comes to pediatric cardiology.

HOWEVER, hopefully through some review and colorful drawings, a few more clinicians will start to feel slightly more comfortable, maybe even find a new enjoyment for pediatric cardiology!

First, we can all start with a rough basic review of how a normal healthy heart pumps blood, and the abbreviations that will be used for the remainder of this article. Blood enters into the Right Atrium (RA), through the tricuspid valve into the Right Ventricle (RV) where it then moves to the Pulmonary Artery (PA) to the lungs. From the lungs blood enters the Pulmonary Veins to the Left Atrium (LA) to the Left Ventricle (LV) via the mitral valve to the aorta and the rest of the body... as illustrated above. Now, let’s get down to business.

Ventricular Septal Defects

Let’s start with the Ventricular Septal Defect (VSD). A VSD is as a hole in the septal wall where non-oxygenated and oxygenated blood will mix in the heart, as seen by the purple coloring in the heart. This is caused by back flow from the LV to RV. Clinical presentations of this abnormality are seen as left sided heart failure that progresses into right sided heart failure. The presence of a VSD can introduce a phenomenon known as shunt. This is when blood moves from left or right circulation into the other via the septal defect. Typically, the pressure is higher in the left side of the heart which leads to a left to right shunt where oxygenated blood is mixing into deoxygenated blood. More problems can occur if shunt becomes right to left, where deoxygenated blood is allowed to enter systemic circulation. This switch occurs when pulmonary pressures increase seen with pulmonary hypertension and other congenital defects.

Atrial Septal Defects

Next, we will move to Atrial Septal Defects (ASD)... There are four types of ASD’s – Ostium Secundum ASD, Ostium Primum ASD, Sinus Venosus ASD, Coronary Sinus ASD. The clinical presentation of ASD are fatigue at play, poor growth, rapid breathing, shortness of breath and frequent respiratory infections.

Ostium Secundum ASD is the most common variation of this abnormality and is when part of the septum fails to close during development.

Ostium Primum ASD is a defective part of the atrioventricular canal, that is associated with a cleft in one of the leaflets of the mitral valve.

Sinus Venosus ASD is an abnormality at the superior vena cava and the right atrium junction. This type of VSD is associated with abnormal drainage from the pulmonary veins to the RA.

Coronary Sinus ASD is the rarest form of ASD. This form of ASD is associated with hole in the wall of the coronary sinus, behind the LA, leading to blood flow from the coronary sinus to the RA.

Patent Ductus Arteriosus

Next up- PDA, and no I don’t mean public displays of affection... Patent Ductus Arteriosus is an opening between the aorta and PA, leading to mixing of oxygenated blood into the PA. The ductus arteriosus is a normal part of fetal circulation and allows blood to essentially bypass the lungs since they are not used for oxygenation in utero. When the baby is born the ductus arteriosus closes gradually allowing normal pulmonary and systemic circulation. When this vessel does not close after birth, it can lead to disease such as pulmonary hypertension and right sided heart failure.

These clinical presentations consist of poor feeding, sweating when crying or feeding, rapid respiratory rate, dyspnea and a rapid heart rate.

Patent Coarctation of the Aorta

Coarctation of the Aorta, a cyanotic lesion, is the narrowing of the aortic arch distal of the left subclavian bifurcation. This is not something that can be diagnosed during ultrasounds and is usually diagnosed after birth when the PDA has closed, which can take up to a few weeks. Some babies diagnosed with Coarctation will also have a VSD.

Clinical presentation of the baby with coarctation include some of the following: pale or cyanotic skin coloring, difficulty breathing and feeding, weakness and higher blood pressure in arms than legs. It should also be noted that with any cyanotic type lesion, babies will NOT respond to oxygen therapy.

Treatment for babies with coarctation consist of prostaglandin therapy that prevents the closure of the PDA and surgical intervention to fix the narrowing of the aorta.


Hypoplastic Left Heart Syndrome

Hypoplastic Left Heart Syndrome, is a rare defect where the left ventricle is significantly under developed and the aorta is also under developed. This is another cyanotic lesion that will not respond to oxygen therapy.

Due to the nature of the LV, clinical presentation of hypoplastic left heart syndrome presents with cyanosis, difficulty breathing and feeding, lethargy, and baseline SpO2 in the 70’s in some cases.

Treatment of hypoplastic left heart syndrome is surgical in nature, consisting of three surgeries- Norwood Procedure, Glen Procedure and Fontana Procedures.


Tricuspid Atresia

Tricuspid Atresia, is an incomplete or nonexistent tricuspid valve, usually associated with a VSD or ASD. As illustrated, the vast majority of the circulating blood is mixed and the RA is filled with nonoxygenated blood with few places to go. Tricuspid Atresia is also associated with an under developed RA or hypoplastic right heart.

This cyanotic lesion presents with shortness of breath/difficulty breathing and feeding, decreased weight and clubbing of fingers associated with heart failure.

Treatment of this abnormality includes prostaglandin therapy and multiple surgical interventions. These surgical interventions include but are not limited to a shunt placement in the first week of life, the Glen procedure at 4 to 6 months, and then the Fontana procedure at 2-3 years of age.

Transposition of the Great Arteries

Transposition of the Great Arteries, is when the outflow tracts of the pulmonary artery and aorta are swapped. Transposition is also associated with PDA and ASD. It should also be known that the coronary arteries that feed the heart are now supplied with MIXED blood from the aorta. Circulation for this abnormality is running parallel, not continuous from Right to Left, as seen above with the mixed blood of the RA, RV and Aorta supplying the body. These patients are reliant on their PDA to survive. If the ductus arteriosus closes the body will receive no oxygenated blood as the pulmonary and systemic circulation will have no connection.

Clinical Presentation of this abnormality is similar to those of the other cyanotic lesions. Babies present with cyanosis, rapid breathing, poor feeding and decreased weight gain. These babies will also not respond to oxygen treatment as this is a cyanotic lesion.

Treatment for these patients includes prostaglandin therapy to maintain PDA, cannulation of Foramen Ovale to allow further mixing of right and left circulation, and surgical procedures to correct the transposition.

Tetrology of Fallot

Tetralogy of Fallot, the combination of FOUR cardiac abnormalities; including overriding the Aorta, stenosis of the PA, Large VSD and Right Ventricular Hypertrophy. This is usually diagnosed in the first weeks of life; however, patients can present throughout childhood or adult life if missed in neonatal stages of life.

Clinical presentation of Tetralogy of Fallot include but are not limited to – irritability, lethargy, cyanosis, heart murmurs, and sudden drops in oxygenation (tet spells). The Tet Spells occur when the shunt becomes more right to left leading to deoxygenated blood entering the systemic circulation. This can happen

in a number of situations including when the child bears down or cries.

Treatment for Tetralogy, ranges from simple manual position changes to manage symptoms to surgical interventions. Laying a patient with Tetralogy on their back with knees to chest will increase peripheral vascular resistance. This increases the pressure in the LV shifting the shunt to be more left to right. Having a child squat or enter a fetal position can have the same benefit. Prostaglandin therapy plays a major role in the management of TOF as well, however multiple surgical interventions within the first year of life, are required to truly correct this abnormality.



Making-A-Pressor by Tom Latosek

Whether you are a brand-new paramedic or nurse or a seasoned critical care provider, chances are you have started or maintained a patient on vasopressors.  They are considered to be one of the hallmark drugs of resuscitation and what we consider to be “life support” drugs.  There are a few key drugs on the market that have fallen into/out of favor over the years for various reasons but there remains a significant amount of controversy on what the “best” agent is to use in a given situation. 
In this article, we step out of the clinical context of what the preferred vasopressor is for a given clinical situation, but instead take a look at the scientific concepts underlying their administration and efficacy as key players in resuscitation.  Specifically, we will look at those vasopressors derived from tyrosine and phenylalanine, though many of the biological concepts presented here extend to many other drugs as well.  It is my hope that by reading on you gain a better understanding of these agents to better apply them in your clinical practice, and that you learn or refresh your knowledge of biology and chemistry along the way.
Let’s dive in…
The Making of a Vasopressor
Above is what looks like a complicated synthesis pathway, a dreaded topic among many students in organic chemistry courses.  In this context, our goal is just to understand how our vasopressors are made in the body, and we can break down this complex pathway into more digestible components. 
First, looking at the picture above we can see that the process of forming the vasopressors: dopamine, noradrenaline (norepinephrine), and adrenaline (epinephrine).
Phenylalanine and tyrosine are both amino acids that are considered to be a part of the 20 essential amino acids the body requires to carry out many of our necessary reactions, and as the building blocks for other compounds (like nerdy legos). 
Both tyrosine and phenylalanine fall into the class of amino acids referred to as aromatics (literally because these enzymes have a sweet odor..).  Let’s talk a little bit of painless organic chemistry and the concept of an aromatic structure.
Aromatic ring structures are considered to be a very versatile form of an organic molecule. One of the most common structures is benzene, an aromatic ring of six carbons forming a hexagon.  The intersecting lines of the hexagons above each represent a carbon
Anytime you observe a second line, it indicates that there are two bonds attaching the carbons.  On most organic structures you will not see hydrogens, but they exist to satisfy a total of 4 bonds made by each carbon.  In this case, there is 1 additional H assumed to be attached to each carbon.
Why do we care so much about this?
It is a basic building block for adding things and moving other groups around, or forming new compounds. This is what makes these aromatic rings so versatile.  Ok, now let’s address how they apply to our vasopressors above.
If we start at tyrosine and we want to get to the compound L-Dopa, we need the compound tyrosine hydroxylase (the finger below) to make that happen.  If we break down the words, anything that contains “-ase” is an enzyme, and hydroxyl groups are the -OH groups you see on many of the molecules above. Legos don't build themselves. You need an enzyme to stack those puppies up!
The basic concept here, to go from tyrosine to L-Dopa we need to add a hydroxyl group (an -OH) to tyrosine.  Once that happens the new compound has different biological characteristics than the previous compound.  Because of the chemistry of the -OH group on L-Dopa it can now bind receptors differently and it reacts differently at physiological conditions inside the body.  
For example, Parkinson’s patients are often administered L-Dopa as part of their treatment regimen to replace needed dopamine in the brain.  L-Dopa can cross the blood brain barrier more readily, so it is administered in the L-Dopa form and converted to dopamine once inside the brain.   Another important point to consider is what we consider “vasopressors” derived from tyrosine, are also neurotransmitters that function within the brain carrying out other functions.
Back to the chemistry… to get from L-Dopa to dopamine, we need to do some rearrangement, and, in the process, we get rid of carbon dioxide. There is a loss of 1 carbon molecule and 2 oxygen molecules and we move the NH2group, called an amino group, to the end of the molecule.  Again, this rearrangement changes how this molecule will interact at different pH levels, with different receptors, and with different membranes.  The molecules are very similar, but the groups attached to them (NH2, OH, etc) change their functional abilities.  
In going from dopamine to noradrenaline (norepinephrine) and from noradrenaline to adrenaline (epinephrine) take a look above to see what’s added and what is re-arranged.  Then look at the arrows and see if you can make sense of the names of the enzymes, or reaction intermediates, that were needed to make those changes occur.  I would explain them here, but I think it would be more beneficial for you to see for yourself how that change occurs now that you have the education to decipher what just a few minutes ago may have looked extremely complex.
Now that the molecule is made, let’s discuss how they work in Part 2! Stay Tuned..
-Tom Latosek

Tom is a practicing paramedic and EMS educator who is interested in EMS research, and advancing the profession of EMS through education.  Tom has practiced in a variety of EMS clinical settings and teaches a variety of courses for a healthcare education company.  Tom holds an MS in neuroscience and a bachelor’s degree in biology and psychology and is currently a first-year medical student.

© 2020 FOAMfrat LLC. All Rights Reserved.