Tetralogy of Fallot

Welcome to PT 635 Pathophysiology of Complex Patient Problems This is a wiki created by and for the students in the School of Physical Therapy at Bellarmine University in Louisville KY. Please do not edit unless you are involved in this project, but please come back in the near future to check out new information!!

Original Editors -   Megan Clayton & Jaclyn Muenchow  from Bellarmine University's Pathophysiology of Complex Patient Problems project.

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Definition/Description

Tetralogy of Fallot is a congenital heart defect which presents with 4 conditions: a ventricular septal defect (a hole between the right and left ventricles), a narrowing of the pulmonary outflow tract (the vessel between the heart and lungs), an overriding aorta (the aorta is shifted to the right instead of being connected strictly to the left side), and hypertrophy of the right ventricle. Each of these components can vary in severity. These defects cause there to be lower oxygen levels in the blood, leading to cyanosis. It is the most common cause of cyanotic cardiac disease in neonates.

http://www.youtube.com/watch?v=yePivAlbR4A.

Prevalence

TOF is categorized as a rare heart disease affecting 5 out of every 10,000 babies.  While it is rare, it is the most common form of congenital cyanotic heart disease.  TOF is responsible for approximately 10% of all cases of congenital heart disease.

Characteristics/Clinical Presentation

 Most babies present with mild to moderate cyanosis, but do not typically present with signs of respiratory distress or heart failure. Symptoms of TOF include:

• cyanosis, which gets worse when the baby is upset
• clubbing of fingers
• fainting
• heart murmurs
• poor appetite and/or slow growth
• tires easily
• has trouble breathing when eating or crying
• squatting episodes during cyanosis

Patients with TOF may experience a hypercanotic spell. They are not common but they can occur in as young as 2 months of age. These spells are characterized by a sudden decrease in oxygen due to acute, almost complete obstruction of subpulmonary outflow. These spells are a medical emergency and can result in death if not treated.
If the child is having a hypercyanotic spell, put his/her knees to chest in order to try to increase venous return to the right side of the heart. Call 911 immediately.

Associated Co-morbidities

Patients with TOF have a higher incidence of other major congenital defects.  Infants with Down Syndrome have a higher incidence of TOF, as do infants with DiGeorge syndrome and branchial arch abnormalities.  Many children who have undergone corrective surgery and their families are not educated on the importance of physical activity and are not given guidelines for physical activity and live sedentary life styles. The sedentary life style can lead to obesity and all the associated co-morbidities, such as diabetes and development of other cardiovascular disease.

Medications

Surgery is the first line of defense in children with TOF. Afterwards, they may or may not be on various medications to help control arrhythmias (if they have one) or to help their heart beat more forcefully. Children after TOF surgery may be required to take antibiotics when going to the dentist to get their teeth cleaned, or if they are around someone that has an infection as an act of prophylactic care.

Diagnostic Tests/Lab Tests/Lab Values

MD’s will diagnosis TOF using 3 methods; baby’s signs and symptoms, physical exam, and the results from diagnostic tests.

The signs and symptoms that MD's use to diagnosis TOF can be found in the above section.

During the physical exam the MD will look for these signs and symptoms and listen to the baby’s heart. A heart murmur is also commonly found with TOF.

The diagnostic tests performed include echocardiography, EKG, chest x-ray, pulse oximetry and cardiac catheterization. 
      :Echocardiography – uses ultrasound waves to create a moving picture of the heart. This allows MDs to see any problems with the way the heart is working and clearly shows the four defects and how the heart is responding to them.
      :EKG (Electrocardiogram) – records the hearts electrical activity. This test will determine if the right ventricle is enlarged. 
      :Chest X-Ray – creates a picture of the chest and the structures of the chest. This will show if the heart is enlarged or if there is any fluid build-up in the lungs, a sign of CHF.
      :Pulse Oximetry – gives an idea of how much oxygen is in the blood at any given time.
      :Cardiac Catheterization – used dye injected into the blood stream to determine if blood is mixing between the right and left side of the heart. MDs also use the cardiac catheterization to measure pressure in the chambers of the heart.

Etiology/Causes

The cause of TOF is unknown, but there are some risk factors:

• chromosomal abnormalities
• gestational diabetes
• untreated phenylketonuria
• excessive alcohol consumption while pregnant
• malnutrition while pregnant
• mother over 40 years old
• rubella or another virus during pregnancy

Systemic Involvement

Tetralogy of Fallot doesn’t directly affect any other systems, but it decreases the amount of oxygen circulating in the blood stream. This decrease in oxygen affects the entire body, and is most noticeable in the integumentary system, bluing of the nails and lips, the musculoskeletal system, decreased endurance and tiring with activity, and the ????? system, fainting or passing out.

Medical Management (current best evidence)

Surgery is the only corrective measures for children born with TOF. There are two different surgical routes the infant may undergo: early/temporary correction, or complete correction. First though, the neonate may be injected with prostaglandin in order to preserve ductal patency and provide a stable blood source to the lungs. Early or temporary correction is done to increase blood flow to the lungs for a period of time until the child is big enough and ready for complete corrective surgery. In this surgery, surgeons place a shunt between the systemic and pulmonary artery in order for the subclavian and pulmonary artery on the same side to communicate.

In a complete repair, surgeons close the hole between the ventricles with a patch, re-channel the aorta to connect with the left ventricle instead of the right, and widen the narrowed pulmonary tract. This surgery is usually performed somewhere between 4-6 months, but is beginning to be introduced in as young as 3 months. A complete repair provides relief of the volume and pressure overload on the right ventricle, minimizing cyanosis (and thus reducing secondary damage to organs), decreasing right ventricular hypertrophy, and reducing the incidence of arrhythmias. Patients who have a successful surgery usually do not need to have another heart surgery in their first year. Longer follow-up is usually necessary with children undergoing a complete correction. There is however, a risk of surgery using the patch between ventricles at such a young age. The patch can create a state of chronic pulmonary regurgitation, which increases morbidity in young adults. This can lead to exercise intolerance and ventricular arrhythmias. The mortality rate of this surgery is less than 3%, and more children are surviving into adulthood than ever before, living normal, healthy lives.

Physical Therapy Management (current best evidence)

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Alternative/Holistic Management (current best evidence)

In one study, percutaneous balloon dilation was performed on children with TOF for palliative purposes after cardiac catheterization. There was immediate improvement in aortic saturation. At the one year follow up, all of the cardiac lesions were successfully corrected. This study supports that balloon dilatation can be used as an alternative palliative therapy for TOF other than the routine surgery options listed above.

Differential Diagnosis

Any other cyanotic heart defects, such as, pulmonary stenosis, transposed arterial trunks, common arterial trunk and tricuspid atresia. Patients with heart murmurs will also be tests for persistent pulmonary hypertension.

Case Reports/ Case Studies

add links to case studies here (case studies should be added on new pages using the case study template)

Resources

Mayo Clinic. Available online at http://www.mayoclinic.com/health/tetralogy-of-fallot/DS00615

Medline Plus. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/001567.htm

Medscape. Available online at http://emedicine.medscape.com/article/2035949-overview#a0101

National Heart, Lung and Blood Institute. Available online at http://www.nhlbi.nih.gov/health/health-topics/topics/tof/

Recent Related Research (from Pubmed)

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see tutorial on Adding PubMed Feed

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References

see adding references tutorial.