About half of all patients are now diagnosed before they are born. Differential diagnosis is when physicians diagnose between two or more conditions for a persons symptoms and this can include primary pulmonary causes of cyanosis, cyanotic heart lesions, pulmonary stenosis and transposed arterial trunks. 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. 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. : 171–72

Electrocardiogram
An electrocardiogram (ECG) is one of the most basic procedures for assessing the heart. 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 hearts electrical activity is then measured. Natural electrical impulses help maintain blood flowing properly by coordinating contractions in different areas of the heart. 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.Electrocardiography shows right ventricular hypertrophy (RVH), along with right axis deviation. RVH is noted on EKG as tall R-waves in lead V1 and deep S-waves in lead V5-V6.
Nasal obstruction – bilateral nasal stuffiness alternates from one site to other; this is more marked at night, when the dependent side of nose is often blocked. Postnasal drip. Complications
Nonallergic rhinitis cases may subsequently develop polyps, turbinate hypertrophy and sinusitis. Pathophysiology
Nasal mucosa has a rich blood supply and has venous sinusoids or "lakes" surrounded by smooth muscle fibers. These smooth muscle fibers act as sphincters and control the filling and emptying of sinusoids. Sympathetic stimulation causes vasoconstriction and shrinkage of mucosa, which leads to decongestion of the nose. Parasympathetic stimulation causes not only excessive secretion from the nasal gland but also vasodilatation and engorgement, which lead to rhinorrhoea and congestion of the nose. The autonomic nervous system, which supplies the nasal mucosa, is under the control of the hypothalamus. Diagnosis
Nose examination: The mucosa is usually boggy and edematous with clear mucoid secretions. The turbinates are congested and hypertrophic.Pharynx examination: Mucosal injection and lymphoid hyperplasia involving tonsils, adenoids and base of tongue may be seen. Investigations
Absolute eosinophil count, nasal smear, skin and in vitro allergy tests to rule out allergic rhinitis, acoustic rhinometry for measuring nasal patency, smell testing, CT scan in cases of sinus disease and MRI in case of mass lesions. Classification
Treatment
Medical
The avoidance of inciting factors such as sudden changes in temperature, humidity, or blasts of air or dust is helpful. Intranasal application of antihistamines, corticosteroids, or anticholinergics may also be used for vasomotor rhinitis. Intranasal cromolyn sodium may be used in patients older than two years.