“Congenital Cardiac Defects with Decreased Pulmonary Blood Flow” by Patricia Lincoln, OPENPediatrics

“Congenital Cardiac Defects with Decreased Pulmonary Blood Flow” by Patricia Lincoln, OPENPediatrics

Congenital Cardiac Defects with Decreased
Pulmonary Blood Flow by Patricia Lincoln. Hello. My name is Trish Lincoln. I’m the clinical nurse specialist in the cardiac
ICU at Children’s Hospital Boston. This lecture will provide information on the
most common congenital heart defects and their surgical repair. I will be discussing the defects with decreased
pulmonary blood flow. Introduction and Pathophysiology. What will happen with congenital heart defects
that cause a decrease in pulmonary blood flow? The decrease in pulmonary blood flow occurs
as blood shunts right to left at either the atria level or ventricular level through a
hole in the septum because the blood is unable to leave the heart due to an obstruction or
defect in a valve, vessel, or chamber on the right side of the heart. In defects with decreased pulmonary blood
flow, there is an obstruction to blood flow on the right side of the heart. The blood must find another exit from the
right side of the heart either through an opening at the atrial level, a patent foramen
ovale still present from uterine life, or an atrial septal defect, or an opening at
the ventricular level– a ventricular septal defect. Because deoxygenated blood from the right
side of the heart is mixing with oxygenated blood returning from the lungs on the left
side of the heart, the patient is cyanotic. Children that are cyanotic for a few years
have problems related to their cyanosis. These children may develop clubbing of their
fingernails. This is related to overgrowth of capillaries
in the fingers in an attempt to bring more oxygen to the tips of the fingers. These children maybe polycythemic, having
hematocrits in the 50-70% range. Because of the increased amount of red blood
cells in the blood, the amount of circulating clotting factors are decreased, and the clotting
factors that are available do not work well in a cyanotic environment. This patient is at risk for hemorrhage, especially
in the post-operative period. The elevated hematocrit also has the patient
at risk for the development of blood clots and infections, specifically bacterial endocarditis. The blood vessels in the lungs may become
damaged by shearing forces and stress from the extra red blood cells and sluggish circulation,
causing higher pressure in the lung blood vessels. The biggest risks for the cyanotic patient
are hypercyanotic spells. Hypercyanotic spells occur when the body needs
more oxygen, and there is less oxygen available. A cyanotic baby or child that cries often
and is very irritable may be having a hypercyanotic spell. If the patient is stressed and the body needs
more oxygen, that may trigger a spell. A spell may also occur spontaneously, or with
feeding, bathing, or intravenous insertion. During anesthesia induction, a spell may occur
as blood shunts right to left through the VSD, due to a decrease in systemic vascular
resistance. Treatment for hypercyanotic spells include
providing supplemental oxygen to the patient. Place the child in a knee-chest position,
lying the child down and bringing their knees bent up to their chest. In doing this, the large muscles of the legs
contract and force more blood back to the heart. This increases preload on the right side of
the heart and possibly forces blood through the spasming right ventricular outflow tract. That same large muscle contraction increases
afterload on the left side of the heart, making it more difficult for blood to shunt right
to left in the heart. Morphine may be administered to relax the
patient, and hopefully relax the right ventricular outflow tract. Volume is administered to increase preload. The patient may require intubation to provide
oxygen and ventilation. The hypercyanotic spell may be so severe that
the patient will experience cardiac arrest and need emergency heart surgery. The defects associated with decreased pulmonary
blood flow that I will be discussing are Tetralogy of Fallot, and transposition of the great
arteries. Tetralogy of Fallot. Patients diagnosed with Tetralogy of Fallot
are at the greatest risk for a hypercyanotic spell. Tetralogy of Fallot is a combination of four
congenital heart defects– a ventricular septal defect; pulmonary stenosis, which is a narrowing
or obstruction involving the pulmonary valve and/or the right ventricular outflow tract;
an overriding aorta, which occurs because the aortic outflow tract does not have a well-developed
pulmonary outflow tract to balance against in utero; and right ventricular hypertrophy,
which develops as the right ventricle attempts to pump against an obstructed or narrowed
pulmonary valve. Children diagnosed which Tetralogy of Fallot
will be cyanotic as the deoxygenated blood on the right side of the heart is unable to
get through the area of obstruction in the pulmonary outflow tract, and flows across
the ventricular septal defect to the left side of the heart and out to the body. The greater the amount of obstruction in the
pulmonary outflow tract, or the greater the degree of pulmonary stenosis, the more cyanotic
the patient will be. The surgical repair for Tetralogy of Fallot
involves the closure of the ventricular septal defect with Dacron or pericardium, and removal
of the muscle bundles from around the pulmonary valve, or right ventricular outflow tract. Also, the right ventriclular outflow tract
or passage out of the right ventricle is opened and widened using a patch. Post-operative concerns after repair of Tetralogy
of Fallot are a residual ventricular septal defect, which is evaluated by checking right
atrial pulmonary artery saturations for an increase in the pulmonary artery saturation. A residual right ventricular outflow tract
obstruction, which is evaluated as the pulmonary artery line is removed. An increase in systolic pulmonary artery pressure
of 10 millimeters of mercury or greater with pulmonary artery line removal may indicate
a residual obstruction or right ventricular dysfunction. Another post operative concern is right ventricular
dysfunction, which would be evidenced by low cardiac output state and congestive heart
failure signs and symptoms. The most common arrhythmia experienced after
repair of Tetralogy of Fallot is junctional ectopic tachycardia. In junctional ectopic tachycardia, the rate
is regular with a normal-looking QRS. The ventricular rate usually ranges from 170
to the high 200s. However, the atrial rate is slower, and it
is difficult to see the P waves. Junctional ectopic tachycardia may be triggered
by catecholamine release associated with a high heart rate that accompanies fever, pain,
or dopamine use. Transposition of the Great Arteries. In transposition of the great arteries, the
pulmonary artery arises from the morphologic left ventricle, and the aorta arises from
the morphologic right ventricle. This results in two parallel circulations
with mixing occurring at the ductal level across the patent ductus arteriosis, and at
the atrial or ventricular level through an atrial septal defect or ventricular septal
defect. The patient is profoundly cyanotic. Transposition of the great arteries accounts
for 10% of all congenital heart disease. There’s a 75% male predominance in transposition
of the great arteries. Repair of transposition of the great arteries
is accomplished with the arterial switch operation. In the arterial switch operation, both great
vessels– the aorta and the pulmonary artery– are resected. The coronary arteries, with some extra tissue,
are removed from the root of the aorta on the right ventricle. The pulmonary artery is sutured into its correct
position on the right ventricle. The aorta is sutured into its correct position
on the left ventricle. And the coronary arteries are reattached to
the aorta. Postoperative concerns following an arterial
switch operation are decreased left ventricular function, as the left ventricle has been pumping
against the low pressure pulmonary system, and now must support systemic circulation. Another concern is coronary artery spasm or
occlusion. There are many suture lines involved in the
reattachment of the great vessels and the reimplantation of the coronary arteries. The suture lines may interfere with the flow
through the coronary arteries. Also, there may be swelling along the suture
lines. And that may affect flow through the coronary
arteries. Also, manipulation of the coronary arteries
may cause coronary artery spasm. These arteries are the blood supply for the
myocardium. So anything that impedes the flow through
these vessels could impact the function of the heart. As the child grows and the coronaries are
stretched more, there is a risk of late occlusion of the coronary arteries. Please help us improve the content by providing
us with some feedback.

3 Replies to ““Congenital Cardiac Defects with Decreased Pulmonary Blood Flow” by Patricia Lincoln, OPENPediatrics”

  1. Cant's begin to tell you how helpful all of your videos have been! What a find – I will tell other nursing students. Thank you!

  2. My child was turning blue after birth (by operation). He died after 4 hours of birth. My wife has water level 3-4 at the time of operation. She completed 9 months at the time of operation. Can anyone tell me, what was happened to my child?

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