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Palliative Operations

Palliative Operations

Over the past several years, the indications for and timings of palliative
procedures have changed. Management is often dependent on the preference of
the cardiologist and surgeon. Hopefully, accumulated data will help provide
the optimal indications for palliative operations in the near future.

1. Types

A. Increase pulmonary blood flow - Aortopulmonary shunt
B. Decrease pulmonary artery blood flow - PA banding
C. Improve mixing - atrial septectomy
D. Reduce ventricular work - Glenn shunt

2. Increase Pulmonary Blood Flow

A. Classic Blalock-Taussig shunt - Subclavian to PA, first performed in 1940s. Constructed on opposite side from arch; orifice of subclavian artery controls flow.
B. Modified Blalock-Taussig - Goretex subclavian to PA. Generally constructed on same side as arch, although either side works; orifice of subclavian or graft itself controls flow.
C. Central - Goretex ascending aorta to main PA
D. Waterston - Ascending aorta to RPA
E. Pott's - Descending aorta to LPA
F. Brock - Pulmonary valvotomy, closed with or without infundibular dilation or resection

3. Indications for Aortopulmonary Shunts

A. Tetralogy of Fallot less than age 3 months, as patient is too small for adequate reconstruction of RVOT
B. Pulmonary atresia with or without VSD
C. Tricuspid atresia with PS
D. Single ventricle with PS
E. TGA with VSD and PS; although there is good mixing at the level of the ventricle, there is inadequate pulmonary flow
F. In summary, aortopulmonary shunts will benefit any patient with pulmonary obstruction, which usually presents as cyanosis, dyspnea, and/or failure to thrive

4. Results of Aortopulmonary Shunts

A. Classic BT shunt - difficult to mobilize subclavian and PA distortion if subclavian too short. Reported complications include arm ischemia and decreased growth, chylothorax, phrenic nerve injury, Horner's syndrome, and endocarditis.
B. Modified BT shunt - easy, less PA distortion, more growth of the pulmonary arteries. Complications include shunt stenosis or thrombosis, less durable than classic BT shunt.
C. Pott's - pulmonary vascular disease from oversized shunt, difficult to take down
D. Waterston - kinking of RPA from malpositioned opening - up to 50%
E. Central - hard to regulate flow
F. All except the central shunt tend to flow more to one lung than the other, resulting in assymetric growth

5. Pulmonary Artery Banding

A. Left or right thoracotomy
B. Encircle PA just above commissures to avoid crimping valve and to avoid stenosis of the right and left pulmonary artery origins
C. Reduce PA pressure to 1/3 systemic
D. Trusler's rule for circumference of band
1) Simple defect (tetralogy, large VSD) = 20 mm + wt (kg)
2) Mixing defect (single ventricle, transposition) = 24 mm + wt (kg)

6. Indications for PA Banding

The most common general indication for banding is congestive heart failure in infancy with anticipated delayed repair. Single ventricle is the most common lesion requiring banding, as this protects the pulmonary bed for future Fontan conversion.
A. Unbalanced AV canal
B. Multiple VSD's
C. VSD and coarctation
D. Single ventricle with increased pulmonary blood flow
E. Contraindications to CPB (intracranial bleeding, thrombocytopenia)
F. Late presentation of TGA (with shunt)

7. Results of PA Banding

A. Mortality = 5-20%, highest in infants < 3mos or with complex lesion
B. Interval mortality variable
C. PA distortion: a low band results in supravalvular PS, a distal band can disrupt the pulmonary bifurcation
D. Subaortic obstruction in single ventricle = 30-40%; hypertrophy behind the band may obstruct interventricular connections

8. Classic Blalock-Taussig Shunt

A. Original experimental shunt failed to produce pulmonary hypertension
B. Blue baby operation, 1945
C. Left or right on opposite side of aortic arch
D. Subclavian artery to PA anastomosis is technically challenging
E. PA distortion

9. Modified Blalock-Taussig Shunt

A. Left or right on the same side of aortic arch
B. 4 mm or 5 mm PTFE
C. Subclavian orifice acts as regulator
D. More reproducible
E. Less PA distortion
F. Better PA growth

10. Increase Mixing

A. Blalock-Hanlon septectomy - closed procedure. Clamp placed behind right pulmonary veins and across portions of both atria. The lateral portion of the atrial septum is excised.
B. Rashkind balloon septostomy - 90% effective.
C. Park - blade septostomy at catheterization. Used for thicker septum or when larger intraatrial communication desired.
D. Open atrial septectomy - concomitant procedure, most commonly during repair of hypoplastic left heart

11. Reduction of Ventricular Work

A. Bidirectional Glenn
1) SVC to PA (end-to-side)
2) Reduced ventricular work
3) Reduces Fontan mortality
4) Flow goes to both lungs, so subsequent Fontan procedure will use both lungs
5) Can be done as preparation for Fontan conversion or in combination with Fontan procedure
6) Much less likely to produce right heart failure from overcirculation as aortopulmonary shunt can
7) Complications include decreased shunt flow over time as pulmonary vascular resistance gradually rises
B. Classical Glenn
1) SVC to RPA (end-to-end)
2) Divides pulmonary circulation
3) Late arterio-venous fistula
4) Diverts all venous return to the larger right lung, so subsequent Fontan procedure can only use the smaller left lung