Palliative Shunts and Outflow Tract Reconstruction

9-1-1. Classic Blalock-Taussig (Subclavian Artery to Pulmonary Artery) Shunt

This operation is rarely performed because most surgeons prefer the more predictable modified Blalock shunt. It may still be useful in cases when the shunt is the end point of treatment because the subclavian artery trunk will grow with the patient.

This procedure is ideally performed by working through a lateral fourth intercostal space thoracotomy on the side ipsilateral to the innominate artery. Postoperative congestive heart failure rarely occurs and the shunt may be simply closed by ligating the subclavian artery at the time of later total repair.

Left Subclavian Artery Repair

innominate artery left carotid artery subclavian artery area of distal stump subclavian artery vagus nerve left pulmonary artery

Figure 9-2. All branches of the subclavian artery and the distal main vessel near the rib margin are ligated and divided. The subclavian artery is shifted from the apex of the chest beneath the vagus nerve and moved caudad for an end-to-side connection with the mid left pulmonary artery. The anastomosis is performed with a 6.0 or 7.0 continuous monofilament suture posteriorly and anteriorly, interrupting the latter in a few places to allow for anastomotic growth. Hemostasis during the anastomosis is accomplished with the clamps on the base of the subclavian artery and on the proximal pulmonary artery. Distal pulmonary artery branches are snared.

The vagus nerve is seen crossing the subclavian artery in the posterior medistinum.

Vagus Nerve Heart Anatomy Thoracotomy

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Figure 9-1. Working through a left thoracotomy in the presence of a right aortic arch and left innominate artery, the mediastinal pleura is incised from the apex of the chest to the hilum. The left pulmonary artery is dissected extrapericardial from its origin to the first branches. The left subclavian artery is dissected from its origin to the rib margin at the thoracic inlet. The innominate artery and proximal right carotid artery are freed from surrounding tissue to allow mobility of the subclavian trunk when it is shifted caudad for the anastomosis.

left subclavian artery vagus nerve innominate artery left carotid artery

Figure 9-1. Working through a left thoracotomy in the presence of a right aortic arch and left innominate artery, the mediastinal pleura is incised from the apex of the chest to the hilum. The left pulmonary artery is dissected extrapericardial from its origin to the first branches. The left subclavian artery is dissected from its origin to the rib margin at the thoracic inlet. The innominate artery and proximal right carotid artery are freed from surrounding tissue to allow mobility of the subclavian trunk when it is shifted caudad for the anastomosis.

subclavian artery area of distal stump subclavian artery

Figure 9-2. All branches of the subclavian artery and the distal main vessel near the rib margin are ligated and divided. The subclavian artery is shifted from the apex of the chest beneath the vagus nerve and moved caudad for an end-to-side connection with the mid left pulmonary artery. The anastomosis is performed with a 6.0 or 7.0 continuous monofilament suture posteriorly and anteriorly, interrupting the latter in a few places to allow for anastomotic growth. Hemostasis during the anastomosis is accomplished with the clamps on the base of the subclavian artery and on the proximal pulmonary artery. Distal pulmonary artery branches are snared.

The vagus nerve is seen crossing the subclavian artery in the posterior medistinum.

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*■ ceph vagus nerve left pulmonary artery

9-1-2. Modified Blalock-Taussig (Subclavian Artery to Pulmonary Artery) Shunt

This shunt is constructed by interposing a synthetic tubular graft between the subclavian and pulmonary arteries. It can be performed in either chest, irrespective of the arch anatomy and the location of the innominate artery. Expanded polytetrafluoroethylene (PTFE) grafts (Gore-Tex® or Impra) are used. A 4-mm graft may be used for infants up to 2 months of age, a 5-mm graft from 3 to 24 months, and a 6-mm graft for children over 2 years. In general, smaller grafts are used during Stage I palliation for hypoplastic left heart syndrome (Chapter 18, Section 18-7). Advantages of this operation over the classic Blalock-Taussig procedure include conservation of the subclavian artery. A graft larger than the subclavian artery may be used, because shunt flow is generally regulated by the size of the subclavian artery; this may result in prolonged shunt patency. Patients are heparinized (lOOU/kg) intraoperatively after hemostasis, following shunt construction, but this is not continued postoperatively.

Right Thoracotomy

superior vena cava innominate artery proximal right subclavian artery right pulmonary artery vagus nerve

Figure 9-3- A right thoracotomy is performed in this child with a right-sided innominate artery. A pleural incision is made from the apex of the chest across the mediastinum to the right pulmonary artery. The proximal right subclavian artery is dissected medial to the vagus nerve. The azygos vein is divided and the superior vena cava is retracted anteriorly. Alternatively, the azygos vein may be left intact and retracted. The paratracheal lymph nodes are removed, and the right pulmonary artery is dissected from its origin to the first branches.

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Figure 9-3- A right thoracotomy is performed in this child with a right-sided innominate artery. A pleural incision is made from the apex of the chest across the mediastinum to the right pulmonary artery. The proximal right subclavian artery is dissected medial to the vagus nerve. The azygos vein is divided and the superior vena cava is retracted anteriorly. Alternatively, the azygos vein may be left intact and retracted. The paratracheal lymph nodes are removed, and the right pulmonary artery is dissected from its origin to the first branches.

Branches The Subclavian Artery

Figure 9-4. A side-biting clamp is placed on the base of the right subclavian artery, working medial to the vagus nerve. A graft to artery, end-to-side anastomosis is performed with a continuous suture. The proximal right pulmonary artery is clamped proximally, and the distal vessel is snared. An end-to-side graft to pulmonary artery anastomosis is performed with a continuous suture. Accuracy must be exercised in estimating the length of the graft; if too long, the graft can kink at lower anastomosis; if too short, the subclavian or pulmonary artery may be distorted, compromising shunt flow.

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Figure 9-4. A side-biting clamp is placed on the base of the right subclavian artery, working medial to the vagus nerve. A graft to artery, end-to-side anastomosis is performed with a continuous suture. The proximal right pulmonary artery is clamped proximally, and the distal vessel is snared. An end-to-side graft to pulmonary artery anastomosis is performed with a continuous suture. Accuracy must be exercised in estimating the length of the graft; if too long, the graft can kink at lower anastomosis; if too short, the subclavian or pulmonary artery may be distorted, compromising shunt flow.

Innominate Artery Flow

left pulmonary artery left subclaviar artery

Figure 9-5. In this child, a left thoracotomy is performed in the presence of a right-sided innominate artery. The proximal left subclavian artery is dissected near its origin at the aortic arch opening the pleura only in this area. The left pulmonary artery is dissected from its origin in the first branch.

left pulmonary artery left subclaviar artery

Figure 9-5. In this child, a left thoracotomy is performed in the presence of a right-sided innominate artery. The proximal left subclavian artery is dissected near its origin at the aortic arch opening the pleura only in this area. The left pulmonary artery is dissected from its origin in the first branch.

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Pulmonary Artery

left pulmonary artery

Figure 9-6. The left pulmonary artery is snared proximally and distally, and an arteri-otomy is made. A continuous suture is placed between the posterior wall of the artery and the posterior part of a tubular Gore-Tex® graft. A continuous suture will be used to construct the anterior part of the anastomosis.

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Figure 9-6. The left pulmonary artery is snared proximally and distally, and an arteri-otomy is made. A continuous suture is placed between the posterior wall of the artery and the posterior part of a tubular Gore-Tex® graft. A continuous suture will be used to construct the anterior part of the anastomosis.

Gore Tex Aortic Graft

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Figure 9-7. The tubular graft is tailored and an end-to-side anastomosis is performed to the proximal left subclavian artery, using a side-biting clamp on the latter vessel.

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Figure 9-7. The tubular graft is tailored and an end-to-side anastomosis is performed to the proximal left subclavian artery, using a side-biting clamp on the latter vessel.

9-1-3. Central Shunt (Ascending Aorta to Main Pulmonary Artery)

An advantage of this shunt is long-term patency, even in small infants with small pulmonary arteries. The anastomosis grows with the patient, providing long-term palliation and blood usually flows equally to both right and left pulmonary arteries. It is simple to close at the time of later corrective surgery by direct suture working through the main pulmonary artery. When pulmonary arteries are minis-cule, the proximal main pulmonary artery can be divided for an end-to-side anastomosis between the distal cut end and the ascending aorta.

The operation is usually performed by working through a median sternotomy, although it can be carried out through a lateral thoracotomy on the side ipsilat-eral to the main pulmonary artery. It may be useful in infants with pulmonary atresia and intact ventricular septum when a shunt is needed after pulmonic valvectomy.

Figure 9-8. A side-biting clamp is placed on the left posterior-lateral ascending aorta, and an elliptical aortotomy is made. A small opening is made in the adjacent main pulmonary artery, with snares around this vessel proximally and distally.

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Figure 9-9. The posterior anastomosis is constructed with a continuous suture of polypropylene.

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Pulmonary Outflow Tract

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Figure 9-10. The anterior anastomosis is constructed with interrupted sutures.

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9-1-4. Reconstruction of Right Ventricular Outflow Tract

When pulmonary arteries are severely hypoplastic and total repair is not possible, palliation may be achieved with reconstruction of the right ventricular outflow tract without closing the ventricular septal defect. Over time, if the pulmonary arteries grow, a significant left-to-right intracardiac shunt will develop, and the ventricular septal defect should be closed.

Palliative Shunt

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Figure 9-11. The infant is placed on cardiopulmonary bypass. Snares for hemostasis are pulled tight around the proximal right and left pulmonary arteries. The right ventricular outflow tract is incised from the os infundibu-lum across the hypoplastic pulmonary valve annulus and main pulmonary artery.

Hypoplastic Pulmonary Valve Annulus
Figure 9-12. An oval PTFE patch is stitched over the outflow tract, starting distally on the main pulmonary artery. Alternatively, a patch of homograft pulmonary artery wall is used. With the latter, hemostasis is improved with less bleeding from needle holes.
Antecubital Fossa Infants
Figure 9-13. The repair is complete with stitching of the patch over the right ventriculotomy.

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Resonance Chamber Anatomy Human

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Figure 9-14. A high right ventriculotomy is made over the infundibular chamber. The os infundibulum is small, and obstruction is due to prominent parietal and septal bands and a muscular infundibular floor.

Infundibulum Pulmonary Artery

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Essentials of Human Physiology

Essentials of Human Physiology

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Responses

  • stefania
    Is there a right and left vagas nerve?
    7 years ago
  • Joshua
    What side is proximal and what side is distal in the 4 chamber heart?
    6 years ago

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