An Interesting Case

The Challenges of Managing a Failed Glenn Palliation for Cardiac Transplantation

By Michael Richards, BM, FRCA and Jeremy Geiduschek, MD
University of Washington School of Medicine
Seattle Children's Hospital
Seattle WA

Background

The patient is a 14-year-old boy presenting for Heart Transplantation in 2010. His underlying diagnosis was hypoplastic left heart syndrome (HLHS) which was managed at another institution until his care was transferred in 2006. The patient’s management prior to transfer included:

1995:
Modified “hybrid” procedure as a neonate involving direct infiltration of formalin to the ductus arteriosus (PDA) to maintain patency, and placement of bilateral branch pulmonary artery (PA) bands.

1995:
Percutaneous stenting of the stenosed PDA, adjustment of the PA bands and blade atrial septostomy.

1996:
“Norwood Glenn” – during this operation the neoaorta (former proximal pulmonary artery) was anastomosed directly onto the underside of the distal transverse aortic arch, the native ascending aorta was left to provide coronary blood flow. The branch PA’s were virtually discontinuous and were reconstructed with a 6mm Gore Tex interposition graft.

1996-2006:
Numerous cardiac catheterizations with placement of multiple PA stents.

He was not considered to be a suitable candidate for Fontan completion due to mildly elevated PA pressures (16 mmHg) and right ventricular dysfunction.

A cardiac catheterization at Seattle Children’s in 2007 revealed branch PA pressures of 12 and 14 mmHg, and bilateral PA wedge pressures of 9 and 10 mmHg. Arterial saturation was in the low 70’s. It was felt that his hemodynamic parameters were favorable to proceed with a Fontan completion with reconstruction of his PA’s. (Figures 1 and 2)

Figures 1 and 2

This procedure was attempted in mid-2007; however, the intraoperative findings included extremely thin walled PA’s with intra-arterial stents almost protruding through the vessel walls and the anastamosis of the pulmonary interposition graft within millimeters of the bifurcation of the left PA into upper and lower lobe branches. The surgical team felt that rather than proceeding with Fontan completion the patient would be better served by heart transplantation and tissue reconstruction of the PA’s.

The patient was listed for transplantation, however due to the patient’s size and weight category (adult) along with the requirement for the donor to have both main and branch PA’s harvested (obviating the option of lung donation) the patient waited over 3 years for a suitable organ to become available.

Case

The patient was brought to the operating room and prepared for cardiopulmonary bypass (CPB) in the standard manner. Large bore vascular access was obtained in anticipation of potentially massive blood loss. During the pre-bypass period he was stable whilst the surgical team dealt with a challenging dissection. The surgical findings of note included:

A large, dilated, heavily calcified neoaorta that was anastamosed directly onto the distal, inferior aspect of the transverse arch.
A small native ascending aorta that joined the distal neoaorta/descending aorta.
The Glenn shunt attached to the right PA with the interposition graft providing flow to the left lung.

The surgeons elected to reconstruct the transverse arch and repair the origin of the ascending aorta under circulatory arrest. Due to size discrepancy it was necessary to insert a collagen impregnated woven graft to ensure unobstructed flow around the transverse arch. The removal of the interposition graft and stents with subsequent PA reconstruction was also performed under circulatory arrest to facilitate visualization.

On removal of the aortic cross clamp trans-esophageal echo demonstrated good left ventricular function but depressed right ventricular (RV) function. Immediately following separation from CPB the right ventricle was severely hypokinetic. It was elected to place the patient on veno-arterial extra corporeal membrane oxygenation (VA-ECMO) to rest the new heart.

The total surgical operative time was 11 hours, the patient received 20 units of platelets, 4 units of cryoprecipitate and 2 units of fresh frozen plasma (FFP) as well as over a liter of salvaged red blood cells and 2 units of packed red blood cells (PRBC’s). He returned to the operating room 12 hours later to re-explore his mediastinum for ongoing hemorrhage and received an additional 10 units of platelets, 2 units of cryoprecipitate, 2 units of FFP and 4 units of PRBC’s.

48 hours following transplantation an attempt to wean the patient from ECMO was unsuccessful. The patient was transferred to the cardiac catheterization lab and imaging demonstrated significant stenosis of both right and left PA’s. Both PA’s underwent balloon angioplasty with stent insertion. Shortly thereafter, the patient was able to be weaned off of ECMO support.

The patient was discharged from hospital 17 days later.

Discussion

This was the second teenage patient with failed Glenn/Fontan circulation that presented to our institution for cardiac transplant within a two-week period which exemplifies the increasing prevalence of this challenging pathophysiology1.

The perioperative care of this patient group is challenging for all parties involved. The surgical team is presented with a complex patient that invariably requires significant surgical correction of both aortic and PA anatomy prior to anastamosis of the new organ. The anesthesiology team has to deal with the physiological consequences of the surgical procedure including the potential for rapid intravascular fluid shifts before, and after the CPB run. This is a particular problem due to circulatory arrest during aortic reconstruction and the high prevalence of both microvascular and macro-vascular aorto-pulmonary collaterals in this patient population2.

It is not often that we care for a patient with single ventricle physiology who has reached mid-adolescence with a Glenn shunt as the primary source of pulmonary blood flow. This provided the surgical team with an additional challenge, since they had to reconstruct the entire proximal branch pulmonary artery tree.

Our patient was also the recipient of one of the early attempts at hybrid palliation of HLHS, in his case the initial attempt to maintain ductal patency involved infiltration with formalin. This was first described by Rudolph3 in 1975 however subsequent studies have demonstrated4 (as was shown also in our patient) that the formalin does not provide long term ductal patency and the implication from our case is that the formalin can have a degenerative impact on the surrounding vascular structures.

The final learning point from our case was the institution of ECMO to support the patient through the early stages following transplantation in a non-urgent and controlled manner. This facilitated RV recovery and allowed subsequent PA stenting to enhance the surgical repair.

References