Patent ductus arteriosus is a heart defect that occurs in around 50% of the preterm or low birth weight infants. It is characterized by the failure of the fetal ductus arteriosus to close after birth. There are certain risk factors which predispose an infant to a patent ductus arteriosus. The most important risk factor is trisomy 21 or Down’s syndrome, which is associated with multiple cardiac defects. Other factors are congenital rubella syndrome, birth at high altitudes, and female gender.

Tricuspid atresia is the third most common form of cyanotic congenital heart disease, with a prevalence of 0.3-3.7% in patients with congenital heart disease. The deformity consists of a complete lack of formation of the tricuspid valve with the absence of a direct connection between the right atrium and right ventricle.The following 3 considerations guide the treatment of infants with tricuspid atresia:- The amount of pulmonary blood flow must be regulated to decrease hypoxemia or symptoms of congestive heart failure.- Myocardial function, the integrity of the pulmonary vascular bed, and pulmonary vascular integrity must be preserved to optimize conditions for a later Fontan operation.- The risk of bacterial endocarditis and thromboembolism must be minimized.Infants with decreased pulmonary blood flow: encompasses most of the infants with tricuspid atresia.Marked cyanosis and hypoxemia characterize the clinical course. Acidaemia may occur if the hypoxemia is profound, and death can ensue.Promptly treat infants with severe hypoxemia with prostaglandin E infusions to maintain patency of the ductus arteriosus and improve pulmonary blood flow.Infants with increased pulmonary blood flow: These infants have an associated unrestrictive ventricular septal defect and transposed great vessels.They present with severe congestive heart failure and benefit from digitalis and diuretic therapy until an operative intervention can be undertaken to restrict the pulmonary blood flow.

Hyperkalaemia presents with high voltage (peaked) T waves on ECG. Other features on ECG include smaller p-waves and wider QRS complexes.

Infective endocarditis occurs when microorganisms enter the bloodstream and infect damaged endocardium or endothelial tissue. It most commonly involves the heart valves (either native or prosthetic), but it may also occur at the site of a septal defect, on the chordae tendineae, or on the mural endocardium. The prototypic lesion is at the site of the infection| the vegetation is a mass of platelets, fibrin, microcolonies of microorganisms, and scant inflammatory cells. Endocarditis is classified as acute or subacute, which applies to the features and the progression of infection until diagnosis.The oral cavity, the skin, and the upper respiratory tract are the primary portals for Streptococcus viridans| Staphylococcus species| and Haemophilus aphrophilus, Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae (HACEK) organisms. Streptococcal and staphylococcal organisms are responsible for more than 80% of cases of bacterial IE.Streptococcus viridans accounts for approximately 50-60% of cases of subacute disease.While S aureus infection is the most common cause of IE, including Prosthetic valve endocarditis, acute IE, and IV Drug Abusers IE

Wolff-Parkinson-White (WPW) syndrome is a pre-excitation syndrome characterised by re-entry tachycardia that most commonly presents as a recurrent supraventricular tachycardia. ECG will show a short PR interval and a prolonged QRS complex.

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.

Tetralogy of Fallot (TOF), a congenital heart defect, includes the following: right ventricular hypertrophy, ventricular septal defect, abnormal position of the aorta and pulmonary valve stenosis. The O2 saturation in patients with TOF is typically lower than normal and the condition usually becomes symptomatic early in life. A feature of the disease with high diagnostic significance is squatting or crouching of the infant as a compensatory mechanism to increase the peripheral vascular resistance.

Kawasaki disease is an acute febrile illness of early childhood characterized by vasculitis of the medium-sized arteries. Diagnostic criteria include fever of at least 5 days duration along with 4 or 5 of the principal clinical features – extremity changes, polymorphous rash, oropharyngeal changes, conjunctival injection and unilateral nonpurulent cervical lymphadenopathy.

The most common congenital cyanotic heart disease and the most common cause of blue baby syndrome, Tetralogy of Fallot shows four cardiac malformations occurring together. These are ventricular septal defect (VSD), pulmonary stenosis (right ventricular outflow obstruction), overriding aorta (degree of which is variable), and right ventricular hypertrophy. The primary determinant of severity of disease is the degree of pulmonary stenosis. Tetralogy of Fallot is seen in 3-6 per 10,000 births and is responsible for 5-7% congenital heart defects, with slightly higher incidence in males. It has also been associated with chromosome 22 deletions and DiGeorge syndrome. It gives rise to right-to-left shunt leading to poor oxygenation of blood. Primary symptom is low oxygen saturation in the blood with or without cyanosis at birth of within first year of life. Affected children ay develop acute severe cyanosis or ‘tet spells’ (sudden, marked increase in cyanosis, with syncope, and may result in hypoxic brain injury and death). Other symptoms include heart murmur, failure to gain weight, poor development, clubbing, dyspnoea on exertion and polycythaemia. Chest X-ray reveals characteristic coeur-en-sabot (boot-shaped) appearance of the heart. Treatment consists of immediate care for cyanotic spells and Blalock–Taussig shunt (BT shunt) followed by corrective surgery.

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.

Blalock-Thomas-Taussig shunt is a surgical procedure done to increase pulmonary blood flow in cases like pulmonary atresia and results in a continuous murmur.The type of murmur which is heard during the systole and remains continuous till the second heart sound is known as a continuous murmur. This murmur is often intense and considered rough. It can also be accompanied by quivering. There are numerous causes of a continuous murmur that differ depending on the location and components of this murmur. It is caused by the shunting of blood from a high-pressure circulation to a low-pressure circulation. Pathological causes of a continuous murmur include patent ductus arteriosus, aortopulmonary window, AV malformation, coarctation of aorta, any acquired trauma, and iatrogenic cause like interventional or surgical procedures.

Tooth extraction or any surgical procedure may introduce bacteria into the blood stream. The most commonly involved organisms include Staphylococcus aureus and Streptococcus viridans. Once in the blood, these organisms have a very high tendency of attaching to the walls of the heart and causing inflammation known as endocarditis.

The heart is the first organ to form and become functional, emphasizing the importance of transport of material to and from the developing infant. It originates about day 18 or 19 from the mesoderm and begins beating and pumping blood about day 21 or 22. It forms from the cardiogenic region near the head and is visible as a prominent heart bulge on the surface of the embryo. Originally, it consists of a pair of strands called cardiogenic cords that quickly form a hollow lumen and are referred to as endocardial tubes. These then fuse into a single heart tube and differentiate into the truncus arteriosus, bulbus cordis, primitive ventricle, primitive atrium, and sinus venosus, starting about day 22. The primitive heart begins to form an S shape within the pericardium between days 23 and 28. The internal septa begin to form about day 28, separating the heart into the atria and ventricles, although the foramen ovale persists until shortly after birth. Between weeks five and eight, the atrioventricular valves form. The semilunar valves form between weeks five and nine.

The most probable diagnosis based on the clinical presentation is myocarditis secondary to Coxsackie virus infection.Myocarditis is an important cause of acquired heart failure. The other infective causes of myocarditis are influenza and adenoviruses, and bacterial causes as seen with Borrelia burgdorferi (Lyme disease). Rheumatic fever is unlikely if the ASO titres are within normal limits. While pancarditis may occur as part of Kawasaki disease| the patient is unlikely to present in failure.

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

The most common congenital cyanotic heart disease and the most common cause of blue baby syndrome, Tetralogy of Fallot shows four cardiac malformations occurring together. These are ventricular septal defect (VSD), pulmonary stenosis (right ventricular outflow obstruction), overriding aorta (degree of which is variable), and right ventricular hypertrophy. The primary determinant of severity of disease is the degree of pulmonary stenosis. Tetralogy of Fallot is seen in 3-6 per 10,000 births and is responsible for 5-7% congenital heart defects, with slightly higher incidence in males. It has also been associated with chromosome 22 deletions and DiGeorge syndrome. It gives rise to right-to-left shunt leading to poor oxygenation of blood. Primary symptom is low oxygen saturation in the blood with or without cyanosis at birth of within first year of life. Affected children ay develop acute severe cyanosis or ‘tet spells’ (sudden, marked increase in cyanosis, with syncope, and may result in hypoxic brain injury and death). Other symptoms include heart murmur, failure to gain weight, poor development, clubbing, dyspnoea on exertion and polycythaemia. Chest X-ray reveals characteristic coeur-en-sabot (boot-shaped) appearance of the heart. Treatment consists of immediate care for cyanotic spells and Blalock–Taussig shunt (BT shunt) followed by corrective surgery.

The most probable diagnosis for the clinical scenario provided is coarctation of the aorta. It contributes to about 4% of all congenital heart disease and is more prominent in males than females.It is associated with trisomy 13 and 18, Turner syndrome, valproate toxicity as well as ventricular septal defects, persistent ductus arteriosus, mitral valve abnormalities and berry aneurysms of the circle of Willis. Other associated cardiac abnormalities include a bicuspid aortic valve (50%), mitral valve disease, aortic regurgitation (20%) and subaortic stenosis. Ninety-eight per cent of coarctations occur at the level of the pulmonary artery after the subclavian artery. It is for this reason that, on observation, the proximal blood pressure varies compared with the distal blood pressure. The blood pressure in the right arm is often higher than that in the left arm. Clinically, these children present with hypertension, prominent carotid pulses, radio-femoral delay, left ventricular hypertrophy and an ejection systolic murmur maximum over the posterior left interscapular area. An apical click over the aortic valve may be heard. Coarctation of the aorta may be simple (post-ductal), or complex (pre-ductal or with a septal defect), and may be associated with aortic stenosis, transposition of the great arteries or a bicuspid aortic valve. The ECG and chest radiograph may be normal. However, as the child enters the first decade, evidence of cardiomegaly, congestive heart failure, post-stenotic dilatation with a dilated subclavian artery and rib notching may be noticed. The ECG may show right ventricular hypertrophy, left ventricular hypertrophy in infancy and right axis deviation. Complications of coarctation of the aorta include left ventricular failure, cerebral haemorrhage, aortic dissection, renal vascular stenosis and infective endocarditis. This condition may result in death due to an aortic aneurysm or rupture in the third or fourth decade of life. It may also cause premature ischaemic heart disease as a result of hypertension. If left untreated, 20% of individuals die before 20 years of age and 80% before 50 years of age. Treatment options include surgical balloon dilatation or the grafting of a subclavian flap, and should surgical correction not normalise the blood pressure, further medical management is required.

The most probable diagnosis for the patient would be DiGeorge syndrome due to 22q11 deletion. It causes embryonic defects of the third and fourth branchial arches. It is sporadic in 90% of cases and 10 % inherited from parents as autosomal dominant.Characterised by distinct facial features (micrognathia, cleft palate, short philtrum, and low-set ears), hypocalcaemia, mental retardation, cardiac defects (especially tetralogy of Fallot), and immune deficiencies.A useful memory aid is CATCH-22:- Cardiac defects- Abnormal facial features- Thymic aplasia/hypoplasia- Cleft palate- Hypocalcaemia/Hypoparathyroidism- 22 – Due to 22q11 deletion

Auscultatory findings of VSD vary with the size of the defect. Small VSDs typically produce murmurs ranging from a grade 1 to 2/6 high-pitched, short systolic murmur (due to tiny defects that actually close during late systole) to a grade 3 to 4/6 holosystolic murmur (with or without thrill) at the lower left sternal border| this murmur is usually audible within the first few days of life (see table Heart Murmur Intensity). The precordium is not hyperactive, and the 2nd heart sound (S2) is normally split and has normal intensity.Moderate to large VSDs produce a holosystolic murmur that is present by age 2 to 3 wk| S2 is usually narrowly split with an accentuated pulmonary component. An apical diastolic rumble (due to increased flow through the mitral valve) and findings of heart failure (e.g., tachypnoea, dyspnoea with feeding, failure to thrive, gallop, crackles, hepatomegaly) may be present. In moderate, high-flow VSDs, the murmur is often very loud and accompanied by a thrill (grade 4 or 5 murmur). With large defects allowing equalization of left ventricular and right ventricular pressures, the systolic murmur is often attenuated.

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.

The murmur and thrill indicate a right outflow tract murmur, coupled with the right ventricular heave suggests right ventricular hypertrophy. The VSD would not have been amenable to surgery due to the child’s size/weight and so instead would have been palliated with a PA band. As the child grows, this band progressively restricts pulmonary blood flow until the left to right shunt has reversed. Then it is time for the band to be removed and the VSD to be closed.Pulmonary atresia is a cyanotic condition, which may be palliated with an arterial duct stent. This answer is incorrect as the stent placement would not require a midline sternotomy and would give a continuous machinery type murmur. Pulmonary stenosis with PDA ligation is incorrect. The murmur, thrill, and heave all match a pulmonary stenosis but in the absence of an additional shunt lesion the child would not be cyanosed.

Heart murmurs are common in healthy infants, children, and adolescents. Although most are not pathologic, a murmur may be the sole manifestation of serious heart disease. Historical elements that suggest pathology include family history of sudden cardiac death or congenital heart disease, in utero exposure to certain medications or alcohol, maternal diabetes mellitus, history of rheumatic fever or Kawasaki disease, and certain genetic disorders. Physical examination should focus on vital signs| age-appropriate exercise capacity| respiratory or gastrointestinal manifestations of congestive heart failure| and a thorough cardiovascular examination, including features of the murmur, assessment of peripheral perfusion, and auscultation over the heart valves. Red flags that increase the likelihood of a pathologic murmur include a holosystolic or diastolic murmur, grade 3 or higher murmur, harsh quality, an abnormal S2, maximal murmur intensity at the upper left sternal border, a systolic click, or increased intensity when the patient stands. Electrocardiography and chest radiography rarely assist in the diagnosis.

The T wave represents ventricular repolarization. Other options:- P wave:Depolarization that spreads from the SA node throughout the atria. The wave lasts 0.08 to 0.1 seconds (80-100 ms).The isoelectric period after the P wave represents the time in which the impulse is travelling within the AV node.- P-R interval:Time from the onset of the P wave to the beginning of the QRS complex. The wave ranges from 0.12 to 0.20 seconds in duration.Represents the time between the onset of atrial depolarization and the onset of ventricular depolarization- QRS complex:It represents ventricular depolarization. The duration of the QRS complex is normally 0.06 to 0.1 seconds.- ST-segment:The isoelectric period following the QRS. It represents the period in which the entire ventricle is depolarized and roughly corresponds to the plateau phase of the ventricular action potential- U wave: It is a small positive wave which may follow the T wave. It represents the last remnants of ventricular repolarization.- Q-T intervalIt represents the time for both ventricular depolarization and repolarization to occur, and therefore roughly estimates the duration of an average ventricular action potential.The interval ranges from 0.2 to 0.4 seconds depending upon heart rate.At high heart rates, ventricular action potentials shorten in duration, which decreases the Q-T interval. Therefore the Q-T interval is expressed as a corrected Q-T (QTc) by taking the Q-T interval and dividing it by the square root of the R-R interval (interval between ventricular depolarizations). This allows an assessment of the Q-T interval that is independent of heart rate.The normal corrected Q-Tc interval is less than 0.44 seconds.

Administration of IV prostaglandin/PGE1 (e.g., alprostadil) is indicated in ductal-dependent CHDs until surgery can be performedMechanism: prostaglandin prevents the ductus arteriosus from closing → creates intentional shunt to allow mixing of deoxygenated with oxygenated blood.

Normal QT interval in a 6 months old baby is < 0.44 seconds. A duration exceeding this value is referred to as QT interval prolongation, which is associated with some important congenital syndromes that include Brugada syndrome which is characterized by vasovagal syncope and sudden cardiac death, Jervell and Lange-Nielsen syndrome which is associated with congenital deafness, Andersen syndrome which is marked by bone deformities, and Timothy syndrome with associated heart disease and immunodeficiency. Romano-Ward syndrome is the commonest cause of congenital QT prolongation with no associated extra-cardiac manifestations. Lown-Ganong-Levine syndrome is characterized by a shortened PR interval and a normal QRS duration.

Several types of right-sided aortic arch exist, the most common ones being right-sided aortic arch with aberrant left subclavian artery and the mirror-image type. The variant with aberrant left subclavian artery is associated with congenital heart disease in only a small minority of affected people. The mirror-image type of right aortic arch is very strongly associated with congenital heart disease, in most cases tetralogy of Fallot. A right-sided aortic arch does not cause symptoms on itself, and the overwhelming majority of people with the right-sided arch have no other symptoms. However when it is accompanied by other vascular abnormalities, it may form a vascular ring, causing symptoms due to compression of the trachea and/or oesophagus.

The most probable diagnosis for this patient would be Coarctation of Aorta (CoA).Infants with CoA present within the first few weeks of life with signs suggestive of congestive cardiac failure and general circulatory shock. In these patients, the aorta is supplied by the right ventricle, via the ductus arteriosus. Pathophysiology:When the left ventricle supplies the aorta via the aortic isthmus, children are usually asymptomatic or may present with occasional complaints of leg pain. Associated cardiac anomalies are uncommon but for a bicuspid aortic valve, which is present in approximately 50% of cases. Good collateral circulation usually develops in these patients, which in the long term, causes notching of ribs. Clinical Presentation:Clinically, there may be hypertension in the upper limbs (or higher BP readings than in the lower limbs), and leg pulses are absent, or weak and delayed. A systolic click and aortic ejection systolic murmur are heard, caused by the bicuspid aortic valve. Management:The primary medical management is to treat hypertension. After stabilization, the patient can undergo definitive surgical repair. Transcatheter balloon angioplasty of the coarctation is controversial, but ballooning +/- stenting of re-coarctation following surgery is commonly performed.Systemic hypertension may occur following repair, even in the absence of re-coarctation necessitating the re-initiation/continuation of antihypertensive therapy in these patients.

PDA is particularly common in premature babies and it is managed by indomethacin administration. However, if PDA is not the only defect, prostaglandin E1 can be administered in order to keep the ductus open until the surgery takes place.

Cyanotic congenital heart disease (CCHD) is a common cause of neonatal morbidity and mortality. They can be classified as CCHD due to:- Right-to-left shunt, associated with the decreased pulmonary flow, e.g., tetralogy of Fallot (TOF), pulmonary atresia, right-sided hypoplastic heart,- Right-to-left shunt, associated with the decreased aortic flow, e.g., left-sided hypoplastic heart, interrupted arch, severe coarctation| – Bidirectional shunt, e.g., TGA, DORV, TA, etc. Eisenmenger syndrome is not a neonatal CCHD| rather it develops later in young adulthood secondary to various CHD.

The murmur of tricuspid valve regurgitation is typically a high-pitched, blowing, holosystolic, plateau, nonradiating murmur best heard at the lower left sternal border. The intensity is variable, but tends to increase during inspiration (Carvallo’s sign), with passive leg raising, after a post-extrasystole pause, and following amyl nitrite inhalation. The intensity of the murmur tends to correlate positively with the severity of regurgitation. Right ventricular enlargement may displace the location of the murmur leftward. Right ventricular failure may abolish respiratory variation. When tricuspid regurgitation is caused by pulmonary hypertension, a pulmonic ejection click may be audible. Severe tricuspid regurgitation is commonly accompanied by a third heart sound emanating from the right ventricle and best heard at the lower left sternal border. Severe tricuspid regurgitation typically produces an accentuated jugular cv wave and may produce hepatic congestion with a pulsatile liver.The auscultatory findings associated with ventricular septal defect are variable, depending on a variety of morphologic and hemodynamic considerations. The systolic murmur associated with a Roger’s-type ventricular septal defect (regurgitant jet flows directly into the right ventricular outflow tract) in patients with low pulmonary vascular resistance is a low to medium pitched, holosystolic murmur with midsystolic accentuation. The intensity of the murmur is typically grade 3 or higher.Patent ductus arteriosus produces a continuous murmur in patients with normal pulmonary vascular resistance.

ASD is an acyanotic congenital heart disease, characterized by the failure of the interatrial septum to form completely, which results in the mixing of left and right-sided blood. There are various types of ASD, some of them are ostium primum septal defect and patent foramen ovale. Clinical findings associated with ASD are a systolic ejection murmur, fixed splitting of second heart sound, prolonged PR interval, both left and right axis deviation (primum and secundum ASD, respectively). The most common finding is an incomplete right bundle branch block.

A ventricular septal defect (VSD) is a common form of congenital heart defects and is characterised by the presence of a hole in the wall that separates the right from the left ventricle. Medium or large defects can cause many complications. One of these complication is Eisenmenger syndrome, characterised by reversal of the shunt (from left-to-right shunt into a right-to-left) ,cyanosis and pulmonary hypertension.

Key observations in the results:

1. Oxygen Saturation Step-Up:
   • There is a significant step-up in oxygen saturation from the right ventricle (72%) to the pulmonary artery (86%). This suggests the presence of left-to-right shunting of blood.
2. Pressure Differences:
   • The pressure in the pulmonary artery is elevated (53/13 mmHg), indicating pulmonary hypertension.

Differential Diagnosis:

1. Patent Ductus Arteriosus (PDA):
   • PDA can cause increased pulmonary blood flow, leading to a step-up in oxygen saturation in the pulmonary artery. The pulmonary artery pressures can also be elevated due to increased blood flow.
2. Primary Pulmonary Hypertension:
   • Typically presents with elevated pulmonary pressures but does not usually show a step-up in oxygen saturation.
3. Pulmonary Stenosis:
   • Would result in elevated right ventricular pressure but would not explain the step-up in oxygen saturation.
4. Septum Primum Atrial Septal Defect (ASD):
   • Would result in a step-up in oxygen saturation from the right atrium to the right ventricle, not between the right ventricle and pulmonary artery.
5. Tetralogy of Fallot:
   • Characterized by right ventricular outflow tract obstruction, VSD, right ventricular hypertrophy, and an overriding aorta. Oxygen saturation levels would typically be lower in the systemic circulation.

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.

The most probable diagnosis for the patient in question is atrioventricular nodal re-entrant tachycardia (AVNRT).The presenting features of the patient are suggestive of supraventricular tachycardia (SVT). The most common form of SVT in children over 8 years old is atrioventricular nodal re-entrant tachycardia. It occurs as a result of an additional electrical circuit in or near the AV node itself.Other options:- Atrial Flutter: is a form of re-entry tachycardia within the atria which then becomes unsynchronised with the ventricles, which is not the case here. Furthermore, it is most common in babies and children with congenital heart disease.- Atrial tachycardia: is a condition where an area of atrium takes over the pacemaker activity of the heart. However, it is relatively uncommon.- Atrioventricular re-entrant tachycardia (AVRT): occurs due to an accessory electrical pathway between the atria and ventricles forming a re-entry circuit. This is the most common cause of SVT in children < 8 years old. One of the specific diagnoses of AVRT is Wolff-Parkinson-White syndrome. However, WPW syndrome is much rarer than AVNRT.- Premature atrial contractions (PACs): are very common in normal, healthy children and adolescents. Occasionally, they can give rise to the feeling of a 'skipped beat'. Fortunately, they are rarely associated with any significant underlying pathology or need to be treated.

The most probable diagnosis in this patient would be pulmonary stenosis. Pulmonary Stenosis:Pulmonary valve murmurs are heard in the upper left sternal edge, associated with a thrill but no desaturation in the absence of an additional shunt. The ECG changes suggest right ventricular hypertrophy. Pulmonary stenosis is often well tolerated in childhood unless severe. These should be monitored with serial echocardiography, and balloon pulmonary valvoplasty should be considered once the pressure gradient reaches 64 mmHg.Other options:- Atrial septal defect: While atrial septal defects are associated with right ventricular outflow tract murmurs, they would not cause a thrill.- Patent ductus arteriosus: PDA murmurs can be audible in the left upper sternal edge, but would normally be audible in the left infraclavicular area and be continuous rather than ejection systolic. This left to right shunt would not cause desaturation but does cause left-sided volume loading and hence left-sided ECG changes.- Tetralogy of Fallot: Ventricular septal defect, overriding aorta, subpulmonary stenosis, and right ventricular hypertrophy. This would often cause a ULSE murmur with a thrill and RVH on ECG. However, this degree of obstruction would cause shunting from right to left, and this child would be desaturated.- Ventricular septal defect: Isolated ventricular septal defects cause pansystolic murmurs at the left lower sternal edge. They would have left-sided ECG changes and normal saturations (in the absence of pulmonary hypertension).

Atrial septal defects may also occur in association with a variety of other congenital heart defects, or in new-borns that are relatively small or premature. The following conditions are associated with an atrial septal defect:Ebstein’s anomalyFoetal alcohol syndromeHolt-Oram syndromeDown syndromeEllis van Creveld syndromeLutembacher’s syndrome Ostium primum defects occur frequently in individuals with Down syndrome or Ellis van-Creveld syndrome.Holt-Oram syndrome characterized by an autosomal dominant pattern of inheritance and deformities of the upper limbs (most often, absent or hypoplastic radii) has been attributed to a single gene defect in TBX5Fragile X syndrome is characterized by moderate intellectual disability in affected males and mild intellectual disability in affected females. The physical features in affected males are variable and may not be obvious until puberty. These symptoms can include a large head, long face, prominent forehead and chin, protruding ears, loose joints and large testes. Other symptoms can include flat feet, frequent ear infections, low muscle tone, a long narrow face, high arched palate, dental problems, crossed eyes (strabismus) and heart problems including mitral valve prolapse.

A ventricular septal defect (VSD) is a common form of congenital heart defects and is characterised by the presence of a hole in the wall that separates the right from the left ventricle. Medium or large defects can cause many complications. One of these complication is Eisenmenger syndrome, characterised by reversal of the shunt (from left-to-right shunt into a right-to-left) ,cyanosis and pulmonary hypertension.

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.

Key Observations:

1. Cyanosis and Low Oxygen Saturation:
   • Central cyanosis indicates mixing of oxygenated and deoxygenated blood.
   • The aortic oxygen saturation is low (76%), indicating a significant amount of deoxygenated blood entering systemic circulation.
2. Pressure Analysis:
   • The right ventricle pressure is significantly elevated (110/6 mmHg), suggesting an obstructive lesion like pulmonary stenosis or an increased volume load due to a shunt.
   • The pulmonary artery pressure is low (20/5 mmHg) despite the high right ventricular pressure, suggesting an obstruction to flow from the right ventricle to the pulmonary artery, consistent with pulmonary stenosis.
3. Oxygen Saturation Analysis:
   • There is a notable drop in oxygen saturation from the left ventricle (87%) to the aorta (76%), indicating a mixture of oxygenated and deoxygenated blood in the systemic circulation, suggestive of a right-to-left shunt.

Differential Diagnosis:

1. Pulmonary Stenosis:
   • Supported by elevated right ventricular pressure and low pulmonary artery pressure.
2. Ventricular Septal Defect (VSD):
   • Would typically cause left-to-right shunting, leading to increased pulmonary blood flow and higher oxygen saturation in the right ventricle and pulmonary artery, which is not observed here.
3. Over-riding Aorta:
   • Seen in conditions like Tetralogy of Fallot where the aorta receives blood from both the right and left ventricles, leading to mixed oxygen saturation.
4. Right-to-Left Shunt:
   • The data indicates a right-to-left shunt, with low oxygen saturation in the aorta, suggesting that deoxygenated blood is bypassing the lungs and entering systemic circulation.
5. Aortic Stenosis:
   • Typically presents with high left ventricular pressure and a pressure gradient between the left ventricle and the aorta, which is not observed here.

Conclusion:

Given the data, the most likely abnormalities present in this patient are Pulmonary Stenosis, Right-to-Left Shunt, and Over-riding Aorta. These findings are consistent with a condition like Tetralogy of Fallot, where all these features are present.

A 3-dimensional transoesophageal echocardiography (3D TEE) provides direct visualization of the entire PFO anatomy and surrounding structures. It allows more accurate diagnosis.

Except Tetralogy of Fallot, the others are acyanotic heart diseases. The cyanotic spells and loss of consciousness are due to spasm of the infundibular septum, which acutely worsens the right ventricular outflow tract obstruction. The given murmur is due to a ventricular septal defect.

Torsade de pointes is an uncommon and distinctive form of polymorphic ventricular tachycardia (VT) characterized by a gradual change in the amplitude and twisting of the QRS complexes around the isoelectric line.Conditions associated with torsade include the following:Electrolyte abnormalities – Hypokalaemia, hypomagnesemia, hypocalcaemiaEndocrine disorders – Hypothyroidism, hyperparathyroidism, pheochromocytoma, hyperaldosteronism, hypoglycaemiaCardiac conditions – Myocardial ischemia, myocardial infarction, myocarditis, bradyarrhythmia, complete atrioventricular (AV) block, takotsubo cardiomyopathyIntracranial disorders – Subarachnoid haemorrhage, thalamic hematoma, cerebrovascular accident, encephalitis, head injuryNutritional disorders – Anorexia nervosa, starvation, liquid protein diets, gastroplasty and ileojejunal bypass, celiac diseaseRisk factors for torsade include the following:Congenital long QT syndromeFemale genderAcquired long QT syndrome (causes of which include medications and electrolyte disorders such as hypokalaemia and hypomagnesemia)BradycardiaBaseline electrocardiographic abnormalitiesRenal or liver failure

Although WPW syndrome is a type of supraventricular re-entrant tachycardia, CCBs are contraindicated in its management. This is because CCBs depress AVN conduction| the current then passes through the accessory pathway (bundle of Kent) instead, causing ventricular tachycardia.

On electrocardiography (ECG), characteristic changes in patients with hypercalcemia include:Tall T wavesReduced QTProlonged and depressed STArrhythmiaOther electrolyte disturbances:Hypokalaemia:Flat T wavesST depressionU waveAtrial and ventricular ectopicsVF and VTHyperkalaemia:Tall T wavesST- changesReduced QT intervalIncreased PR intervalSmaller or absent P wavesWidened QRS, broadening to VFHypocalcaemia:Prolonged QTProlonged STFlat or absent T wavesU waves