**7. Stenosis and regurgitation of valves**

If there is stenosis of atrioventricular valves, it causes systemic or pulmonary venous conges‐ tion, depending on the valves involved. Regurgitant lesions cause volume loading of both upstream and downstream chambers. Unlike stenotic lesions which cause pressure overload, regurgitation lesions cause volume overload.

Aortic regurgitation causes wide pulse pressure and the regurgitating jet causes diastolic flutter of mitral valve causing the Austin Flint murmur, and the jet also causes the mitral valve to close early and reduces the intensity of S1. Aortic regurgitation in children usually occurs as a part of ventricular septal defect when the leaflets either attempt to close the defect or get sucked in due to Bernouilli effect, or prolapse due to lack of support to the leaflets due to absence of continuity of media.

Pulmonary regurgitation is common after TOF repair and the significance of which depends on the diastolic distensibility of the right ventricle: patients with diastolic dysfunction of the RV tolerate PR better with less dilatation, and narrow QRS. TR causes prominent liver and neck pulsations.

#### **7.1. Cyanotic heart defects pathophysiology – TGA and Truncus arteriosus**

TGA is one of the common cyanotic conditions presenting in infancy where the aorta arises from the RV and PA arises from the LV. The systemic blood reaches the RV and from there to aorta and again back to RV,(the blood flow is parallel rather than in series). Such an arrange‐ ment is incompatible with life in the absence of atrial, ventricular or ductal level communica‐ tion. In the presence of inadequate communication, they can present with very poor saturations (30-50%) with acidosis and hypoglycaemia in the first week of life. Of all the levels of com‐ munication the atrial septal defect provides the best area of mixing without streaming and atrial septostomy (Rashkind procedure) done for this purpose is the first palliative intervention for a congenital heart disease, which started off the practice of pediatric interventional cardiology.

Any newborn with deep cyanosis and cardiomegaly (egg on side appearance) and increased pulmonary vascular marking and no murmur can be diagnosed to have TGA. Patients with VSD present a little late with features of early CHF and these patients are prone to develop very early pulmonary hypertension, because they get relatively desaturated blood under high pressure. The unique feature of pulmonary circulation of 'hypoxic vasoconstriction ' acceler‐ ates the onset of pulmonary vascular disease.TGA, VSD and PS can occur and the presentation of which depends on the degree of reduction of pulmonary blood flow.

Truncus arteriosus has complete mixing of systemic and pulmonary blood and the level of saturation is proportional to the degree of pulmonary blood flow.

### **7.2. Pathophysiology of Tetralogy of Fallot**

In PDA in addition there is enlargement of aorta and transverse aortic arch, which is usually not very evident in on X-ray as the aortic arch does not form a part of cardiac silhouette. As the PVR increases, there can be differential cyanosis with lower limb saturations being lower

Endocardial cushion defects present with features of both ASD and VSD. The QRS axis is abnormal between -20 to -150 degree, which is due to the disposition of the His bundle and its

Obligatory shunts are those where the degree of shunting does not depend on the PVR, examples of which is Gerbode defect where is there is LV to RA shunt or ruptured sinus of

If there is stenosis of atrioventricular valves, it causes systemic or pulmonary venous conges‐ tion, depending on the valves involved. Regurgitant lesions cause volume loading of both upstream and downstream chambers. Unlike stenotic lesions which cause pressure overload,

Aortic regurgitation causes wide pulse pressure and the regurgitating jet causes diastolic flutter of mitral valve causing the Austin Flint murmur, and the jet also causes the mitral valve to close early and reduces the intensity of S1. Aortic regurgitation in children usually occurs as a part of ventricular septal defect when the leaflets either attempt to close the defect or get sucked in due to Bernouilli effect, or prolapse due to lack of support to the leaflets due to

Pulmonary regurgitation is common after TOF repair and the significance of which depends on the diastolic distensibility of the right ventricle: patients with diastolic dysfunction of the RV tolerate PR better with less dilatation, and narrow QRS. TR causes prominent liver and

TGA is one of the common cyanotic conditions presenting in infancy where the aorta arises from the RV and PA arises from the LV. The systemic blood reaches the RV and from there to aorta and again back to RV,(the blood flow is parallel rather than in series). Such an arrange‐ ment is incompatible with life in the absence of atrial, ventricular or ductal level communica‐ tion. In the presence of inadequate communication, they can present with very poor saturations (30-50%) with acidosis and hypoglycaemia in the first week of life. Of all the levels of com‐ munication the atrial septal defect provides the best area of mixing without streaming and atrial septostomy (Rashkind procedure) done for this purpose is the first palliative intervention for a congenital heart disease, which started off the practice of pediatric interventional

**7.1. Cyanotic heart defects pathophysiology – TGA and Truncus arteriosus**

than the upper limb reflecting right to left shunt at the level of PDA.

**7. Stenosis and regurgitation of valves**

regurgitation lesions cause volume overload.

absence of continuity of media.

neck pulsations.

cardiology.

Valsalva [14]

234 Principles and Practice of Cardiothoracic Surgery

branches intrinsic to the pathology and not due to hemodynamic consequence.

This is commonest cause of cyanosis in children in developing countries. Though classically supposed to have the features of a) VSD b) Aortic over-ride c) RV hypertrophy and d) Right ventricular outflow tract (RVOT) obstruction, the two important features are


If a child presents clinically with signs of small VSD with RVH, it strongly suggests diagnosis of TOF, the probability of which increases in the presence of right aortic arch.

The intensity and the duration of heart murmur are inversely proportional to the severity of pulmonary stenosis. In pulmonary atresia or in cyanotic spells when there is critical reduction in pulmonary flow there may be no murmur at all due to absence of flow across the RVOT

There are no signs of CHF in TOF because no chamber is under volume overload and only RV is under pressure overload which is not suprasystemic and is well tolerated.

The degree of cyanosis depends on the balance between the systemic and pulmonary resis‐ tances, and decrease in SVR due to activities like crying and defecation can increase the degree of R-> L shunt.

The role of RVOT spasm in the development of cyanotic spell is controversial

Hyperpnoea plays an important role in the perpetuation of cyanotic spell as it increases the venous return and more desaturated blood enters the systemic circulation due to override.

Termination of a spell can be achieved by


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

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.

**Pulmonary arterial hypertension**: Is said to occur when the mean pulmonary artery pressure

The Basis of Management of Congenital Heart Disease

http://dx.doi.org/10.5772/53654

237

Severe PAH (50 mmHg) - there is central dilation with reduction in the calibre of peripheral vessels (peripheral pruning). The size of the pulmonary artery correlates with PAH, and it has been found that plethora correlates better with the degree of left to right shunt than cardio‐

**a.** Redistribution of blood flow (10-20mm Hg) – Cephalization due to dilation of upper zone

**c.** Alveolar oedema- (25 – 35 mm Hg) causes the 'Bat's wing appearance' when the interstitial

The presence of prominent aortic knuckle points to the presence of extra cardiac left to right shunt like PDA, Sinus of Valsalva rupture, Coronary arteriovenous fistula, or AP window. The absence points to intra- cardiac L-> R shunt like atrial septal defect and ventricular septal defect.

In addition to the above findings careful consideration should be given to lung parenchyma to look for any parenchymal patches and also the status of spine and bony thorax for complete

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

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

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‐

procedures, TEE probes can now be placed in children as small as 3.5 kg.

imaging, preoperative, intraoperative, postoperative and follow-up imaging.

cation, filtering and is analysed to display in a moving real-time format.

**Pulmonary venous hypertension** – normal 8-12 mm Hg, and gradual increase causes:

**b.** Interstitial oedema – (15-25 mm Hg) Kerley lines and peribronchial cuffing

fluid accumulates at rate faster than it can be removed by lymphatics.

In mild PAH – (20-29 mmHg) there is prominent pulmonary artery.

Moderate PAH- (30-49), the central vessels dilate further,

vessels and blurring of lower zone vessels

is > 20 mmHg,

megaly.

preoperative assessment.

**9. Echocardiography**

The different modes of imaging are

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. Murmur is usually soft or absent.

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 TAPVC. [15]
