Editing Tetralogy of Fallot (section)

== Diagnosis ==
[[File:HeartTOP.jpg|thumb|A chest X-ray of a child with tetralogy of Fallot]]
There are three different useful diagnostic tests used for the diagnosis of tetralogy of Fallot.<ref name="Bailliard_2009">{{cite journal | vauthors = Bailliard F, Anderson RH | title = Tetralogy of Fallot | journal = Orphanet Journal of Rare Diseases | volume = 4 | pages = 2 | date = January 2009 | pmid = 19144126 | pmc = 2651859 | doi = 10.1186/1750-1172-4-2 | doi-access = free }}</ref> These include a chest radiograph, electrocardiogram, and echocardiogram.<ref name="Bailliard_2009" /> The echocardiography determines the final diagnosis and typically offers enough information for surgical treatment planning.<ref name="Bailliard_2009" /> About half of all patients are now diagnosed before they are born.<ref name="Bailliard_2009" /> Differential diagnosis is when physicians diagnose between two or more conditions for a person's symptoms and this can include primary pulmonary causes of cyanosis, cyanotic heart lesions, pulmonary stenosis and transposed arterial trunks.<ref name="Bailliard_2009" />

=== Chest radiograph ===
Before more sophisticated techniques became available, chest X-ray was the definitive method of diagnosis. The abnormal "[[coeur-en-sabot]]" (boot-like) appearance of a heart with tetralogy of Fallot is classically visible via chest X-ray, although most infants with tetralogy may not show this finding.<ref>{{cite web| vauthors = Weerakkody Y |title=Tetralogy of Fallot – Radiology Reference Article |url=http://radiopaedia.org/articles/tetralogy-of-fallot|url-status=live|archive-url=https://web.archive.org/web/20120220221208/http://radiopaedia.org/articles/tetralogy-of-fallot|archive-date=2012-02-20|website=radiopaedia.org|date=17 October 2009 }}</ref> The boot like shape is due to the right ventricular hypertrophy present in TOF. Lung fields are often dark (absence of interstitial lung markings) due to decreased pulmonary blood flow.<ref name="Abdulla_20112">{{Cite book| vauthors = Abdulla R |title=Heart diseases in children : a pediatrician's guide |date=2011 |publisher=Springer |isbn=9781441979940 |location=New York|pages=169–70|oclc=719361786|name-list-style=vanc}}</ref>{{rp|171–172}}

=== Electrocardiogram ===
An electrocardiogram (ECG) is one of the most basic procedures for assessing the heart.<ref name="Woods_1952">{{cite journal | vauthors = Woods A | title = The electrocardiogram in the tetralogy of Fallot | journal = British Heart Journal | volume = 14 | issue = 2 | pages = 193–203 | date = April 1952 | pmid = 14916062 | pmc = 479443 | doi = 10.1136/hrt.14.2.193 }}</ref> Tiny electrodes are applied to specific areas on the body, near the chest, arm, and neck. Lead cables connect the electrodes to an ECG machine. The heart's electrical activity is then measured.<ref name="Woods_1952" /> Natural electrical impulses help maintain blood flowing properly by coordinating contractions in different areas of the heart.<ref name="Woods_1952" /> These impulses are recorded by an ECG, which shows how fast, the rhythm, intensity and timing of the electrical impulses as they travel through the heart.<ref name="Woods_1952" />

Electrocardiography shows right ventricular hypertrophy (RVH), along with right axis deviation.<ref name="Francois_2016" /> RVH is noted on EKG as tall R-waves in lead V1 and deep S-waves in lead V5–V6.<ref>{{Cite web|date=2018-08-01|title=Right Ventricular Hypertrophy (RVH) • LITFL • ECG Library Diagnosis|url=https://litfl.com/right-ventricular-hypertrophy-rvh-ecg-library/|access-date=2019-01-21|website=Life in the Fast Lane|language=en-US|archive-date=2019-01-22|archive-url=https://web.archive.org/web/20190122044412/https://litfl.com/right-ventricular-hypertrophy-rvh-ecg-library/|url-status=live}}</ref>

=== Echocardiogram ===
Congenital heart defects are now diagnosed with [[echocardiography]], which is quick, involves no radiation, is very specific, and can be done prenatally.<ref>{{Cite web|title=Congenital Heart Defects {{!}} National Heart, Lung, and Blood Institute (NHLBI)|url=https://www.nhlbi.nih.gov/health-topics/congenital-heart-defects#Signs,-Symptoms,-and-Complications|access-date=2019-02-01|website=www.nhlbi.nih.gov|archive-date=2018-10-22|archive-url=https://web.archive.org/web/20181022221210/https://www.nhlbi.nih.gov/health-topics/congenital-heart-defects#Signs,-Symptoms,-and-Complications|url-status=live}}</ref>

[[Echocardiography]] establishes the presence of TOF by demonstrating a VSD, RVH, and aortic override. Many patients are diagnosed prenatally. Color Doppler (type of echocardiography) measures the degree of pulmonary stenosis. Additionally, close monitoring of the ductus arteriosus is done in the neonatal period to ensure that there is adequate blood flow through the pulmonary valve.<ref name="Francois_2016" /><ref name="Abdulla_20112" />{{rp|171–172}}

In certain cases, coronary artery anatomy cannot be clearly viewed using echocardiogram. In this case, cardiac catheterization can be done.<ref name="Munoz_2010" />{{rp|37, 201}}

=== Genetics ===
From a genetics perspective, it is important to screen for DiGeorge in all babies with TOF.<ref name="Munoz_2010" />{{rp|37, 201}}