User:Bcatt/d-tga treatment sandbox
dextro-Transposition of the great arteries (d-Transposition of the great arteries, dextro-TGA, or d-TGA) is a cyanotic congenital heart defect (CHD) in which the primary arteries (the aorta and the pulmonary artery) are transposed. Treatment of this condition involves palliating the patient
With simple d-TGA, if the foramen ovale and ductus arteriosus are allowed to close naturally, the newborn will likely not survive long enough to receive corrective surgery. With complex d-TGA, the infant will fail to thrive and is unlikely to survive longer than a year if corrective surgery is not performed. In most cases, the patient's condition will deteriorate to the point of inoperability if the defect is not corrected in the first year.
While the foramen ovale and ductus arteriosus are open after birth, some mixing of red and blue blood occurs allowing a small amount of oxygen to be delivered to the body; if ASD, VSD, PFO, and/or PDA are present, this will allow a higher amount of the red and blue blood to be mixed, therefore delivering more oxygen to the body, but can complicate and lengthen the corrective surgery and/or be symptomatic.
Modern repair procedures within the ideal timeframe and without additional complications have a very high success rate.
If the diagnosis is made in a standard hospital or other clinical facility, the baby will be transferred to a children's hospital, if such facilities are available, for specialized paediatric treatment and equipment. The patient will require constant monitoring and care in an intensive care unit (ICU).
Palliative
[edit]Palliative treatment is normally administered prior to corrective surgery in order to reduce the symptoms of d-TGA (and any other complications), giving the newborn or infant a better chance of surviving the surgery. Treatment may include any combination of:
Medical imaging
[edit]- Echocardiogram
- Chest x-ray
- Magnetic resonance imaging (MRI)
- Computed tomography (CT) scan
Each type of medical imaging has its merits and drawbacks, so they are usually used in combination to provide as complete a model as possible from which to plan and prepare for the corrective surgery. Medical imaging may also be used to moniter how well the heart is functioning, or to determine whether a treatment is having the desired effect.
Surgery
[edit]Minor
[edit]Cardiac catheterization is a minimally invasive procedure which provides a means of performing a number of other procedures.
A balloon atrial septostomy is performed with a balloon catheter, which is inserted into a foramen ovale, PFO, or ASD and inflated to enlarge the opening in the atrial septum; this creates a shunt which allows a larger amount of red blood to enter the systemic circulation.
Angioplasty also requires a balloon catheter, which is used to stretch open a stenotic vessel; this relieves restricted blood flow, which could otherwise lead to CHF.
An endovascular stent is sometimes placed in a stenotic vessel immediately following a balloon angioplasty to maintain the widened passage.
Angiography involves using the catheter to release a contrast medium into the chambers and/or vessels of the heart; this process facilitates examining the flow of blood through the chambers during an echocardiogram, or shows the vessels clearly on a chest x-ray, MRI, or CT scan - this is of particular importance, as the coronary arteries must be carefully examined and "mapped out" prior to the corrective surgery.
It is commonplace for any of these palliations to be performed on a d-TGA patient.
Moderate
[edit]- Left anterior thoracotomy
- Isolated pulmonary artery banding (PAB)
- Left lateral thoracotomy
- PAB (when coarctation or aortic arch repair also required)
- Right lateral thoracotomy
Each of these procedures is performed through an incision between the ribs and visualized by echocardiogram; these are far less common than heart cath procedures.
Pulmonary artery banding is used in a small number of cases of d-TGA, usually when the corrective surgery needs to be delayed, to create an artificial stenosis in order to control pulmonary blood pressure; PAB involves placing a band around the pulmonary trunk, this band can then be quickly and easily adjusted when necessary.
An atrial septectomy is the surgical removal of the atrial septum; this is performed when a foramen ovale, PFO, or ASD are not present and additional shunting is required to raise the oxygen saturation of the blood.
Major
[edit]- Median sternotomy
- PAB (when intracardiac procedures also required)
- Concomitant atrial septectomy
In recent years, it is quite rare for palliative procedures to be done via median sternotomy. However, if a sternotomy is required for a different procedure, in most cases all procedures that are immediately required will be performed at the same time.
Monitering and maintenance
[edit]
- Nasogastric tube (NG tube or simply NG)
- Intubation, oxygen mask, or nasal cannula
- Intravenous drip (IV)
- Arterial line
- Central venous catheter
- Fingerprick
- Sphygmomanometer
- Pulse oximeter
- EKG
An NG tube is used to deliver nourishment, and occasionally medication, to the patient. Since the tube extends right into the stomach, it can also be used to monitor how well the patient is digesting their "food". Paediatric units normally provide facilities and equipment for mothers of infant patients to pump their breastmilk, which can then be fed to the infant through the NG tube, and/or stored for later use.
Oxygen therapy is commonplace for hospitalized d-TGA patients. This may range from an oxygen mask resting on the bed nearby their head to intubation. In some cases, patients are intubated as a precaution; the machine can monitor breathing and supplement the patient as much or as little as they need.
IV's are used to deliver medication, blood products, or other fluids to the patient. Arterial lines provide a constant monitor of blood pressure, as well as a method of obtaining samples for blood gas tests; central lines can also monitor blood pressure and provide blood samples, as well as provide a means to deliver medication and nourishment; fingerpricks (or heelpricks on small babies) are used to obtain blood samples for certain tests.
A sphygmomanometer may be used for intermittent blood pressure monitoring even if a patient is being otherwise monitored using a central or arterial line.
A pulse oximeter is attached to a finger or toe and provides constant or intermittent monitoring of the blood's oxygen saturation level.
An EKG creates a visual readout of how well the heart is functioning.
Medication
[edit]When PGE is administered to a newborn, it prevents the ductus arteriosus from closing, therefore providing an additional shunt through which to provide the systemic circulation with a higher level of oxygen.
Antibiotics may be administered preventatively. However, due to the physical strain caused by uncorrected d-TGA, as well as the potential for introduction of bacteria via arterial and central lines, infection is not uncommon in pre-operative patients.
Diuretics aid in flushing excess fluid from the body, thereby easing strain on the heart.
Analgesics normally are not used pre-operatively, but they may be used in certain cases. They are occasionally used partially for their sedative effects.
Cardiac glycosides are used to maintain proper heart rhythm while increasing the strength of each contraction.
Sedatives may be used palliatively to prevent a young child from thrashing about or pulling out any of their lines.
Corrective
[edit]Arterial switch
[edit]
The Jatene procedure surgery is the preferred, and most frequently used, method of correcting d-TGA; ideally, it is performed on an infant between 8-14 days old.
The heart and vessels are accessed via median sternotomy, and a cardiopulmonary bypass machine is used; as this machine needs its "circulation" to be filled with blood, a child will require a blood transfusion for this surgery. The procedure involves transecting both the aorta and pulmonary artery; the coronary arteries are then detached from the aorta and reattached to the neo-aorta, before "swapping" the upper portion of the aorta and pulmonary artery to the opposite arterial root. Including the anaesthesia and immediate post operative recovery, this surgery takes an average of approximately six to eight hours to complete.
Some arterial switch recipients may present with post-operative pulmonary stenosis, which would then be repaired with angioplasty, pulmonary stenting via heart cath or median sternotomy, and/or xenograft.
Atrial switch
[edit]In some cases, it is not possible to perform an arterial switch, either because of late diagnosis, sepsis, or a contraindicative coronary artery pattern. In the case of sepsis or late diagnosis, a delayed Arterial Switch can sometimes be made possible by PAB, which may also require a concomitant construction of an aortic-to-pulmonary artery shunt.
When an arterial switch is impossible, an atrial switch will be attempted using either the Senning or Mustard procedure. Both methods involve creating a baffle to redirect red and blue blood flow to the appropriate artery. Since the late 1970s the Mustard procedure has been preferred.
Post-operative
[edit]Following corrective surgery but prior to cessation of anaesthesia, two small incisions are made immediately below the sternotomy incision which provide exit points for chest tubes used to drain fluid from the thoracic cavity, with one tube placed at the front and another at the rear of the heart.
The patient returns to the ICU post-operatively for recovery, maintenance, and close observation; recovery time may vary, but tends to average approximately two weeks, after which the patient may be transferred to a Transitional Care Unit (TCU), and eventually to a cardiac ward.
Post-operative care is very similar to the palliative care received, with the exception that the patient no longer requires PGE or the surgical palliation procedures. Additionally, the patient is kept on a cooling blanket for a period of time to prevent fever, which could cause brain damage. The sternum is not closed immediately which allows extra space in the thoracic cavity, preventing excess pressure on the heart, which swells considerably following the surgery; the sternum and incision are closed after a few days, when swelling is sufficiently reduced.
Follow-up
[edit]The infant will continue to see a cardiologist on a regular basis. Although these appointments are required less frequently as time goes on, they will continue throughout the lifetime of the individual, and may increase in the event of complications or as the individual approaches middle age.
The cardiology exam may include an echocardiogram, EKG, and/or cardiac stress test in addition to consultation.
Additionally, some individuals may require ongoing medication therapy at home, which may include diuretics (such as lasix or spironolactone), analgesics (such as tylenol), cardiac glycosides (such as digoxin), anticoagulants (such as heparin or aspirin), or other medications. If the individual has undergone stenting, an anticoagulant will be a necessity to prevent build-up around the stent(s), as the body will perceive the foreign body as a wound and attempt to heal it.