**9. Echocardiography**

**7.3. Pathophysiology of Tricuspid atresia and TAPVC**

Murmur is usually soft or absent.

236 Principles and Practice of Cardiothoracic Surgery

TAPVC. [15]

**8. Chest X-ray**

This is a single ventricle physiology where there is enlargement of RA, LA and LV and hypoplastic RV. 70% have normally related great arteries and 30% have transposed great arteries. In either of these situations the pulmonary blood flow can be increased or decreased. QRS axis is deviated leftward with LVH and the axis resembles endocardial cushion defect.

TAPVC – Total anomalous pulmonary venous connection can present as supracardiac, cardiac and infracardiac.The timing of clinical presentation depends on the presence of obstruction.

Non- obstructed TAPVC presents like large ASD. Obstructed variant can present with extremely sick child with pulmonary venous congestion causing ground glass appearance on chest X-ray, severe cyanosis, respiratory distress and severe pulmonary arterial hypertension.

Any child with features of pulmonary oedema and ground glass appearance on chest X-ray with normal size cardiac shadow and no murmurs should be considered to have obstructed

The x-ray helps in the evaluation of cardiomegaly, chamber size, and blood flow by looking at the pulmonary artery and venous markings. Lungs, spine, thorax and visceral situs are also evaluated using x-ray. For example the presence of aortic knuckle and gastric fundus on the

The structures forming the margin of the heart on the right side are– SVC, aortic knuckle and

Different conditions can have diagnostic X-ray features. TOF has a *' boot shaped'* heart, TGA has a '*egg on side'* heart and supracardiac TAPVC is associated with '*snow man sign'* the left vertical vein, the innominate vein and the right superior vena cava form the head of the snowman., Truncus, the dilated pulmonary artery particularly the right pulmonary artery produces the ' *comma or the water fall sig*n'. In Ebsteins anomaly there is cardiomegaly with a narrow pedicle, with '*Pencil line sharp'* cardiac borders.These classic appearances are not

Pulmonary plethora – the presence of right descending pulmonary artery larger than the size of trachea is a sensitive sign of increased pulmonary blood flow. Other signs are prominent upper and lower zone vessels and vessels seen in the outer third of the lungs. Infants and

RA and on the left side they are the pulmonary artery, left atrial appendage and LV.

usually seen, though they are supportive evidences in broader clinical context.

**8.1. The assessment of pulmonary arterial and venous pressure using X-ray**

children present with generalized mottling, due to increased pulmonary flow.

X-ray is integral part of the evaluation of a child with cardiac disease.

same side is suggestive of corrected transposition.

Using ultrasound to visualize organs was first introduced in the 1970's and over the 1980's it transformed the field of imaging becoming the primary diagnostic modality for evaluation of congenital heart disease. During the 90's and 2000's steady progress has been made in the areas of 3D imaging, myocardial function assessment and trans-esophageal echocardiogra‐ phy(TEE).TEE is now routinely used intraoperatively for planning and performing cardiac procedures, TEE probes can now be placed in children as small as 3.5 kg.

Echo is non-invasive, has excellent spatial and temporal resolution, ability to see the anatomy and physiology in real time along with portability. Echo is now everywhere right from prenatal imaging, preoperative, intraoperative, postoperative and follow-up imaging.

A burst of ultrasonic energy is produced by the piezoelectric crystals placed on the transducer probe which passes through the tissue and the returning ultrasound is processed by amplifi‐ cation, filtering and is analysed to display in a moving real-time format.

The different modes of imaging are

**a.** M- Mode – uses a narrow ultrasound beam to provide a 'ice pick' image of the structure. It has good axial resolution. Used to measure the degree of movement of leaflets. Chamber thickness is measured using 2-D directed M-mode imaging.

**b.** Gradient Echo - sequences uses radiofrequency pulses that are less than 90 degrees, that are faster than spin Echo images and used to produce images in which the flowing 'blood appears white'. 'Steady State free precession' MR sequences allow real time MR fluoro‐ scopy, with shorter imaging times. Used to assess ventricular function and flow of blood

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Myocardial tagging – uses 'spatial modulation of magnetization' so that protons in selected volume are incapable of producing a signal. This produces stripes across the image, tagging the myocardium. As the heart moves the tags are followed and this allows calculation of

Velocity encoded Cine MRI- can be used to measure blood flow velocity and quantify blood flow rate.- can measure the regurgitation volume and can even calculate the shear stress

Contrast enhanced MRI – Uses gadolinium chelate which produces bright blood signal used for clear delineation of spatial relationship and for imaging of baffles and outflow tracts. Hyper enhancement of myocardial regions observed 10-15 minutes after administration of gadolini‐

MRI in patients younger than 5-6 years would require sedation, Surgical clips, sternotomy wires, coils stents and occluding devices are MRI safe once the surrounding fibrous tissue grows over these implants and makes them immobile. Cardiac pacemakers, presence of intracranial, intra ocular or intracochlear implant are considered contraindication to MRI.

Cardiovascular MRI is fast becoming a tool which can provide us with anatomic and functional

Catheterisation used to be the main diagnostic modality available when it was first introduced in 1946. The era of angiographic anatomic delineation is fading. Echocardiography is now preferred for evaluation of valvar and congenital cardiac defects with 3D echo promising real time surgical images of the valves for repair. MRI and CT angiography is fast replacing angiogram for delineation of complex relationship, volume estimation of chamber, extra cardiac vessels, aortic arches and venous anomalies. The field of MR imaging, has the potential to completely replace diagnostic angiography. The routine use of catheterization before single ventricle surgeries is being questioned, as the same information can be made available through

**a.** Visualising branch PA anatomy beyond hilum- in case of tetralogy of Fallot with aorto‐

in the cardiac pathways and for identifying stenotic or regurgitant jets.

um contrast is indicative of scar tissue and irreversible myocardial injury.

information not provided by echo or cardiac catheterization. [17]

**11. Cardiac catheterisation and interventions**

myocardial strain

non-invasive means

Angiogram still has a role in

pulmonary collaterals

**b.** Coronary anatomy.

exerted by the blood on the vessel wall.

