The most possible diagnosis is SVT. The boy is suffering from hemodynamic instability, as indicated by his cold extremities. DC cardioversion is the treatment of choice.

The overall diagnosis is Fallot’s tetralogy. Ventricular septal defect with left to right shunt is indicated by drop of oxygen saturation from left atrium to left ventricle. Pulmonary stenosis is indicated by the pressure difference between the pulmonary artery and the right atrium. There is oxygen saturation drop from the left ventricle to the aorta which can be due to the overriding aorta.

Pulmonary arterial hypertension (PH) is noted in 9 to 35 % of patient with a secundum type ASD. The haemodynamic definition of PH is a mean pulmonary arterial pressure (mPAP) of ≥25 mmHg at rest by means of right heart catheterization. In ASD, The findings on physical examination depend on the degree of left-to-right shunt and its hemodynamic consequences, which, in turn, depends on the size of the defect, the diastolic properties of both ventricles, and the relative resistance of the pulmonary and systemic circulations.Blood flow across the atrial septal defect (ASD) does not cause a murmur at the site of the shunt because no substantial pressure gradient exists between the atria. However, ASD with moderate-to-large left-to-right shunts results in increased right ventricular stroke volume across the pulmonary outflow tract creating a crescendo-decrescendo systolic ejection murmur. This murmur is heard in the second intercostal space at the upper left sternal border.Patients with large left-to-right shunts often have a rumbling mid-diastolic murmur at the lower left sternal border because of increased flow across the tricuspid valve.ASD is an acyanotic lesion. Thus, the patient should be normally saturated. In the rare case of severe pulmonary arterial hypertension, atrial shunt reversal (Eisenmenger syndrome) may occur, leading to cyanosis and clubbing

Coarctation of the aorta is one of the serious forms of congenital heart diseases characterized by a congenitally narrowed down proximal thoracic aorta. This narrowing is usually located distal to the origin of the left subclavian artery. Coarctation can occur in isolation but can accompany other cardiac lesions, including a bicuspid aortic valve. When the coarctation is located just above the left subclavian artery, raised blood pressure can be noted in the right arm. The most common type of murmur found in coarctation of the aorta is a diastolic murmur of aortic regurgitation due to the presence of a bicuspid aortic valve. Exercise augmented cardiac output is only affected in cases where coarctation of the aorta leads to heart failure. Hypertension persists even after the surgical repair and needs to be closely monitored.

Ebstein’s anomaly is characterised by apical displacement and adherence of the septal and posterior leaflets of the tricuspid valve to the underlying myocardium, thereby displacing the functional tricuspid orifice apically and dividing the right ventricle into two portions. The main haemodynamic abnormality leading to symptoms is tricuspid valve incompetence. The clinical spectrum is broad| patients may be asymptomatic or experience right-sided heart failure, cyanosis, arrhythmias and sudden cardiac death (SCD). Many Ebstein’s anomaly patients have an interatrial communication (secundum atrial septal defect (ASD II) or patent foramen ovale). Other structural anomalies may also be present, including a bicuspid aortic valve (BAV), ventricular septal defect (VSD), and pulmonary stenosis. The morphology of the tricuspid valve in Ebstein anomaly, and consequently the clinical presentation, is highly variable. The tricuspid valve leaflets demonstrate variable degrees of failed delamination (separation of the valve tissue from the myocardium) with fibrous attachments to the right ventricular endocardium.The displacement of annular attachments of septal and posterior (inferior) leaflets into the right ventricle toward the apex and right ventricular outflow tract is the hallmark finding of Ebstein anomaly.

Infective endocarditis (IE) is an acute infective pathology of the endocardium secondary to some underlying cardiac pathology like VSD and TOF. Most commonly, it is bacterial in origin, caused by staphylococcus aureus in the majority of cases. Clinical features include fever, arthralgias, weight loss, anorexia, new-onset, or changing existing murmur. Skin manifestations include Osler’s nodes, Janeway lesions, splinter haemorrhages, and clubbing. Roth spots are conjunctival haemorrhages found in IE. Beau’s lines are not found in IE.

Tetralogy of Fallot usually is diagnosed after a baby is born, often after the infant has an episode of turning blue during crying or feeding (a tet spell). A loud heart murmur is usually present.An atrial septal defect is present at birth, but many babies do not have any signs or symptoms.Coarctation of the aorta is usually diagnosed after the baby is born. How early in life the defect is diagnosed usually depends on how mild or severe the symptoms are. New-born screening using pulse oximetry during the first few days of life may or may not detect coarctation of the aorta.In babies with a more serious condition, early signs usually include:pale skinirritabilityheavy sweatingdifficulty breathingBabies born with pulmonary atresia will show symptoms at birth or very soon afterwards. They may be cyanotic. However, it is not uncommon for a heart murmur to be absent right at birth.

Infective endocarditis (IE) is defined as an infection of the endocardial surface of the heart.Fever, possibly low-grade and intermittent, is present in 90% of patients with IE. Heart murmurs are heard in approximately 85% of patients.One or more classic signs of IE are found in as many as 50% of patients. They include the following:- Petechiae: Common, but nonspecific, finding- Subungual (splinter) haemorrhages: Dark-red, linear lesions in the nail beds -Osler nodes: Tender subcutaneous nodules usually found on the distal pads of the digits- Janeway lesions: Nontender maculae on the palms and soles- Roth spots: Retinal haemorrhages with small, clear centres| rareSigns of neurologic disease, which occur in as many as 40% of patients, include the following:- Embolic stroke with focal neurologic deficits: The most common neurologic sign- Intracerebral haemorrhage- Multiple microabscessesOther signs of IE include the following:- Splenomegaly- Stiff neck- Delirium- Paralysis, hemiparesis, aphasia- Conjunctival haemorrhage- Pallor- Gallops- Rales- Cardiac arrhythmia- Pericardial rub- Pleural friction rub

Coarctation of the aorta may be defined as a constricted aortic segment that comprises localized medial thickening, with some infolding of the medial and superimposed neointimal tissue.The presence of associated defects and aortic arch anomalies, the extent of patency of the ductus arteriosus, the rapidity of the process of closure of the ductus arteriosus, and the level of pulmonary vascular resistance determine the timing of clinical presentation and the severity of symptoms. Young patients may present in the first few weeks of life with poor feeding, tachypnoea, and lethargy and progress to overt CHF and shock. These patients may have appeared well before hospital discharge, and deterioration coincides with closure of the patent ductus arteriosus. Presentation may be abrupt and acute with ductal closure.Neonates may be found to have tachypnoea, tachycardia, and increased work of breathing and may even be moribund with shock. Keys to the diagnosis include blood pressure (BP) discrepancies between the upper and lower extremities and reduced or absent lower extremity pulses to palpation. However, when the infant is in severe heart failure, all pulses are diminished.The murmur associated with coarctation of the aorta may be nonspecific yet is usually a systolic murmur in the left infraclavicular area and under the left scapula.

Infective endocarditis (IE) is caused by a bacterial, or fungal infection which damages the heart’s endothelium and can thus lead to changes in heart function, valve incompetencies, possible cardiac failure, as well other associated skin and organ changes. Organisms common in IE include Staphylococcus aureus and Streptococcus viridians. The HACEK organisms (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella species) are common in neonates. The Duke criteria uses 2 major, or 1 major and 3 minor criteria, or 5 minor criteria to diagnose infective endocarditis. Major criteria include:- a positive blood culture and evidence of endocardial involvement. Minor criteria include: – evidence of predisposition (a heart condition of injection drug use)- a fever- vascular phenomena such as Janeway lesions- immunologic phenomena such as Osler’s nodes and Roth’s spots| and- microbiological or serological evidence of active infection.