Palliative Procedures
Palliative procedures are indicated for the management of pulmonary blood flow in patients who cannot safely undergo definitive repair until a later time. Most of the procedures are indicated to increase the delivery of desaturated venous blood to the lungs in patients with obstructive right heart defects who are severely cyanotic, hypoxic, metabolically acidotic, and present with respiratory distress. The procedures are meant to decrease cyanosis and polycythemia and to increase the capacity of the left atrium and left ventricle.
Pulmonary artery banding (Muller-Dammann) is indicated to decrease pulmonary blood flow in patients with a large left-to-right shunt at the ventricular level. Potential benefits of PA banding include the control of cardiac failure and prevention of pulmonary hypertension.
1. Blalock-Taussig Shunt
Definition:
A subclavian artery to pulmonary artery anastamosis.
Advantages:
Predictability of flow, shunt may grow with the child, post-op congestive heart failure is less common than with other procedures, graft thrombosis is uncommon.
Disadvantages:
Inadequate flow is possible, stenosis of the anastomosis is possible due to increased tension on the vessel, possible injury to the phrenic nerve, pulmonary hypertension is possible, small diameter of the subclavian may result in worsened hypoximia.
Uses:
Tetralogy of Fallot - can restore partial blood flow in the obstruction of the pulmonary circulation.
Tricuspid Atresia - improves oxygenation of the desaturated blood due to the the shunt to the pulmonary circulation.
Pulmonary Atresia - creates a shunt between systemic and pulmonary circulations.
2. Potts
Definition:
A descending aorta to the left pulmonary artery anastomosis. A direct side to side anastomosis.
Advantages:
The ease of construction of the side to side anastomosis.
Disadvantages:
The flow is dependant on the size of the anasomosis, no conduit to regulate flow, CHF may occur due to the large left to right shunt, pulmonary artery hypertension may occur.
Uses:
May be used in Tetralogy of Fallot, tricuspid atresia, and pulmonary atresia to increase the diminished blood flow to the pulmonary circulation.
3. Cooley
Definition:
An ascending aorta to the main pulmonary artery anastamosis. Proposed for branch pulmonary stenosis where Blalock-Taussig procedure is difficult.
Advantages:
Provides a balanced shunt flow to both pulmonary arteries. Little pulmonary distension occurs, easy to close at the time of definitive operation, provides excellent palliation of cyanosis.
Disadvantages:
Common for the PA to kink resulting in unequal flow to the lungs and hypoplasia of the lower flow pulmonary artery. Excessive flow may cause CHF, flooding of the lungs, pulmonary edema, and left hear failure.
Uses:
Tetralogy of Fallot, pulmonary atresia, and tricuspid atresia. Increases the flow of blood into the low pressure pulmonary vasculature.
4. Rashkind
Definition:
Enlargement of an atrial septal defect (ASD) using balloon septostomy.
Advantages:
Increased oxygen saturations, decreased left atrial pressure, and atrial pressure gradients.
Disadvantages:
Tricuspid valve damage is possible, cardiac perforation, dysrhythmias, low cardiac output due to the formation of the shunt.
Uses:
Tricuspid atresia, pulmonary atresia, mitral atresia, total anomalous pulmonary vein return, mitral stenosis, hypoplastic left heart syndrome, double outlet right ventricle with restrictive VSD.
5. Blalock-Hanlon
Definition:
Excision of the atrial septum. Allows mixing of the blood between right and left atria by forming an ASD.
Advantages:
Increased oxygen saturations, decreased left atrial pressure, and atrial pressure gradients.
Disadvantages:
Tricuspid valve damage is possible, cardiac perforation, dysrhythmias, temporary occlusion of the right pulmonary veins may cause severe atrial desaturation and hemorrhage in lungs secondary to pulmonary venous obstruction.
Uses:
The patency of the ASD is important in various congenital defects, such as tricuspid atresia, pulmonary atresia, hypoplastic left heart, and the transposition of the great arteries. This procedure is usually employed when less invasive Rashkind procedure is not possible due to further development of the septum.
6. Glenn Procedure
Definition:
A superior vena cava (SVC) to pulmonary artery anastomosis. This is an end to side anastomosis where the right pulmonary artery is divided at the distal end and is attached to the side of the SVC.
Advantages:
Pulmonary hypertension is rare (blood is being shunted under low venous pressure), does not increase the volume of work on the heart (amount of blood returned to the heart is unchanged).
Disadvantages:
Cyanosis may increase by the decreased perfusion to bothlungs, may call for a second palliative procedure such as Blalock-Taussig. Polycythemia secondary to hypoximia may increase blood viscosity and decrease flow through the pulmonary vascular bed thus decreasing oxygen saturations. Shunt is only effective if the child weighs over 8 kg. If the child's weigh is less than 8 kg, then Waterson shunt is more effective.
Uses:
Used to bypass the right heart, therefore becomes useful in anomalies where right side obstruction occurs, such as tricuspid atresia or tricuspid stenosis.
7. Waterson
Definition:
An ascending aorta to right pulmonary artery anastomosis.
Advantages:
Increased flow of blood to the low pressure pulmonary vasculature.
Disadvantages:
Large size of the anastomisis, inability to regulate flow.
Uses:
Tetralogy of Fallor, tricuspid atresia, and pulmonary atresia. Increases the flow of blood to the pulmonary system and helps with oxygenation of the desaturated blood.
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