**6.5 Common atrioventricular canal (CAVC)**

It is also called endocardial cushion defect and results from failure of endocardial cushions to fuse with lower part of atrial and upper portion of ventricular septum. In addition, atrioventricular valves will also be abnormal. There are three different types of CAVC exist.

	- a. Usually interatrial communication and cleft mitral valve
	- b. Two separate AV valves
	- a. Ostium primum plus
	- b. Partially separated AV valves
	- c. Small to moderate VSD partially closed by chordate attachment
	- a. Large non restrictive ostium primum
	- b. Large VSD
	- c. Large common single atrioventricular valve

Left to right shunting and regurgitation leads to volume loading of both atria and both ventricles. Patient will develops pulmonary congestion and pulmonary hypertension. Surgery usually performed at the age of 2-5 years and in some cases earlier.

#### **Anaesthetic management**

Management depends on severity of pulmonary hypertension and degree of left to right shunting. FiO2 and ventilation is manipulated along with use of NO and analgesics to reduce pulmonary hypertension. Ionotropic support will be required after bypass. TEE will be useful in detecting residual defects and ventricular function. LA line along with other invasive lines will help in deciding about escalation in ionotropes.

#### **6.6 Anomalous pulmonary venous connection**

Two types of abnormal communication are seen. Both of these defects may be associated with other cardiac lesions like ASD, VSD and PDA.

	- a. At least one pulmonary vein is connected to right atrium either directly or indirectly. Most common is right upper pulmonary vein opening in the superior vena cava. These patients may remain asymptomatic for long time.
	- a. All four pulmonary veins opens in the right atrium.
	- b. Four types of TAPVR exist
		- i. Supra cardiac
			- Pulmonary veins converge and drains into a vertical vein which then drains into right atrium via innominate V or SVC
		- ii. Cardiac
			- Common pulmonary confluence drains into coronary sinus
		- iii. Infra cardiac or infra diaphragmatic
			- A common confluence of pulmonary vein passes through diaphragm and drains in the portal system which then drains into inferior vena cava.
		- iv. Mixed
			- Pulmonary veins drains at two or more levels.

Pathophysiology of TAPVR depends on obstructed or non obstructed pulmonary venous return. Obstruction will leads to pulmonary venous hypertension and higher back pressures.

#### **Anaesthetic considerations**

PAPVR is associated with higher pulmonary blood flow, so main aim would be to reduce pulmonary blood flow. Patients with obstructed TAPVR are sicker and will need higher PaO2, ionotropic support and repeated blood gases to control acidosis. Post bypass period require high PaO2, hyperventilation, ionotropic support, good sedation, paralysis and NO. Intraoperative TEE is usually not done to avoid further obstruction of pulmonary veins but TTE and epicardial echo can be performed to look at venous return in the left atrium.

## **6.7 Transposition of the great vessels**

Transposition is a common CHD which is associated with high mortality without intervention. Atrial septostomy is usually performed in the catheterization laboratory to stabilize the patient before surgery. PgE1 should be continued before bypass to keep the duct opens. Coronary artery21 should be preoperatively assessed as abnormal location of coronaries creates surgical difficulties.

#### **Anaesthetic considerations**

Anaesthetic goal is to avoid reduction in cardiac output and systemic vascular resistance while keeping the PVR lower relative to SVR. Increased pulmonary blood flow due to reduced PVR will leads to increased mixing of blood and better saturation. Pulmonary resistance can be reduced by following measures:

	- a. Increased FiO2
	- b. Reduced carbon dioxide

c. Alkalotic PH

70 Perioperative Considerations in Cardiac Surgery

drains into right atrium via innominate V or SVC

Pulmonary veins drains at two or more levels.

Common pulmonary confluence drains into coronary sinus

Pathophysiology of TAPVR depends on obstructed or non obstructed pulmonary venous return. Obstruction will leads to pulmonary venous hypertension and higher back

PAPVR is associated with higher pulmonary blood flow, so main aim would be to reduce pulmonary blood flow. Patients with obstructed TAPVR are sicker and will need higher PaO2, ionotropic support and repeated blood gases to control acidosis. Post bypass period require high PaO2, hyperventilation, ionotropic support, good sedation, paralysis and NO. Intraoperative TEE is usually not done to avoid further obstruction of pulmonary veins but TTE and epicardial echo can be performed to look at venous return in the left

Transposition is a common CHD which is associated with high mortality without intervention. Atrial septostomy is usually performed in the catheterization laboratory to stabilize the patient before surgery. PgE1 should be continued before bypass to keep the duct opens. Coronary artery21 should be preoperatively assessed as abnormal location of

Anaesthetic goal is to avoid reduction in cardiac output and systemic vascular resistance while keeping the PVR lower relative to SVR. Increased pulmonary blood flow due to reduced PVR will leads to increased mixing of blood and better saturation. Pulmonary

Pulmonary veins converge and drains into a vertical vein which then

 A common confluence of pulmonary vein passes through diaphragm and drains in the portal system which then drains into inferior vena

2. Total anomalous pulmonary venous return (TAPVR)

iii. Infra cardiac or infra diaphragmatic

b. Four types of TAPVR exist i. Supra cardiac

cava.

**6.7 Transposition of the great vessels** 

coronaries creates surgical difficulties.

resistance can be reduced by following measures:

3. Sildenafil (Oral and preferably intravenous)

**Anaesthetic considerations** 

1. Inhaled nitric oxide (NO)

4. Ventilatory interventions a. Increased FiO2

b. Reduced carbon dioxide

2. Nebulized PGI2

ii. Cardiac

iv. Mixed

**Anaesthetic considerations** 

pressures.

atrium.

a. All four pulmonary veins opens in the right atrium.

5. At the same time avoid hypoxia, hypercarbia, acidosis, hypothermia, high and low tidal volume, high PEEP and hypoglycaemia in neonates.
