Procedure

Orthotopic heart transplantation for congenital heart defects: situs inversus

Department of Pediatric Cardiac Surgery, Groupe Hospitalier Necker – Enfants Malades, 149 rue de Sèvres, 75015 Paris, France

^* Corresponding author: ^* Tel.: +33-1-44381867; fax: +33-1-44381911 E-mail: pascal.vouhe{at}nck.aphp.fr

	Summary

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Although rare, visceroatrial situs inversus is not exceptional in patients with complex congenital heart defects. Achieving orthotopic heart transplantation using a graft harvested in a donor with situs solitus is surgically demanding. Technical problems can, however, be overcome by adequate harvesting of donor heart and by the use of innovative reimplantation techniques. These include: separate right and left pulmonary venous anastomoses, creation of an atrio-pericardial tunnel for reimplantation of the inferior vena cava, extracardiac reconstruction of the superior vena cava pathway using the donor innominate vein, direct aortic and pulmonary arterial reconstruction after adequate mobilization. There is evidence that the early risk of heart transplantation is not increased by the presence of recipient situs inversus.

Key Words: Congenital heart defects • Situs inversus • Orthotopic heart transplantation

	Introduction

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Although rare, visceroatrial situs inversus is not exceptional in patients with complex congenital heart defects, particularly in those with univentricular physiology. Heart transplantation may, therefore, be indicated in case of ventricular failure. As the probability to find a suitable donor with situs inversus is extremely low, innovative techniques have been designed to allow orthotopic transplantation in a recipient with situs inversus using a graft harvested in a donor with situs solitus [1,2,3,4,5].

	Surgical technique

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The main surgical principles are: (1) extended donor heart harvesting, (2) extensive mobilization of the extracardiac vessels after recipient heart excision, (3) total cardiac replacement with separate extracardiac vascular anastomoses.

Donor operation (Schematic 1)
Donor heart harvesting includes the entire aortic arch, the pulmonary artery bifurcation and the main pulmonary arteries, the superior vena cava and the innominate vein, most of the transdiaphragmatic inferior vena cava and the pulmonary veins. Adequate partitioning of the veins needs collaboration with the surgical teams who eventually harvest the liver and the lungs. The donor descending aorta may also be harvested to allow specific vascular reconstruction.

View larger version (78K): [in this window] [in a new window]   Schematic 1 Appearance of the heart procured from a donor with situs solitus that will be used for transplantation into a recipient with situs inversus (posterior view). The superior vena cava and the innominate vein are harvested. Sufficient aortic and pulmonary artery length is obtained to meet specific requirements. Two separate orifices are created in the posterior wall of the left atrium with incisions between the superior and inferior pulmonary venous orifices on each side.

Recipient operation
Cardiopulmonary bypass is instituted using an arterial cannula in the distal ascending aorta and two venous cannulae placed directly into the superior vena cava and the inferior vena cava as distally as possible. Cardiopulmonary bypass is conducted in normothermia.

Recipient heart excision (Schematic 2)
The heart is removed from the thorax in the usual fashion leaving two sizeable atrial cuffs. The left pericardium is widely excised to allow left-sided rotation of the graft once reimplanted. To prevent right-sided luxation of the graft and subsequent obstruction to venous inflow, implanting a pericardial prosthetic mesh at the end of the procedure may be necessary.

View larger version (65K): [in this window] [in a new window]   Schematic 2 Appearance of the recipient mediastinum after cardiectomy. The ascending aorta is divided and the distal aortic arch is mobilized down to the aortic isthmus. Similarly, after division of the pulmonary trunk, the pulmonary bifurcation and the main pulmonary arteries are mobilized extensively down to both pulmonary hila (including division of the ligamentum arteriosum). The incisions used to prepare the recipient atria are shown in red dotted lines. The separation of each atrium from the other at the atrial septum level is begun (Sondergaard maneuver). The pulmonary atrial wall is divided between the right and left pulmonary veins.

View larger version (55K): [in this window] [in a new window]   Schematic 3 Preparation of the recipient atria. The left-sided superior vena cava is divided and extensively mobilized (including division of the azygos vein). The systemic atrium has been separated from the pulmonary atrium at the atrial septum which leaves the systemic atrial wall attached to the inferior vena cava. The systemic atrial remnants are used as a flap to construct a composite conduit from the orifice of the left-sided inferior vena cava across the midline to the right side. The systemic atrial wall is cut back to the orifice of the inferior vena cava. The medial edge of this orifice is sewn to the pericardium on the surface of the diaphragm. The systemic atrial flap is sewn to the pericardium to create a tunnel that crosses the midline to reach a point on the right side that will approximate the position of the donor inferior vena cava orifice. This conduit is therefore made of atrial wall superiorly and pericardium inferiorly (see insert). Two separate sizeable cuffs of pulmonary arterial wall are created around both the right and left pulmonary venous ostia and the pulmonary veins are dissected free as far as possible.

View larger version (101K): [in this window] [in a new window]   Schematic 4 Reimplantation of the pulmonary veins. The recipient pulmonary venous cuffs are anastomosed to the orifices created in the donor left atrial wall. This is greatly facilitated by the previous mobilization of the recipient pulmonary veins.

View larger version (63K): [in this window] [in a new window]   Schematic 5 Cardiac reimplantation. The orifice of the donor inferior vena cava is anastomosed to the right-sided orifice of the composite conduit previously constructed to divert the recipient inferior vena cava. The ascending aorta and the main pulmonary trunk are reconstructed by direct end-to-end anastomosis; this is made easy by previous extensive mobilization of both recipient aortic arch and pulmonary arterial branches. The orifice of the donor right brachiocephalic vein is oversewn and the conduit formed by the donor superior vena cava and innominate vein is anastomosed end-to-end to the left-sided superior vena cava of the recipient and positioned anterior to the great arteries. Again, this is facilitated by extensive mobilization of the recipient left superior vena cava.

	Comments

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Orthotopic heart transplantation for situs inversus remains, however, technically demanding and requires careful planning.

Reconstruction of the aortic and pulmonary arterial pathways is not difficult if extra lengths of donor vessels are harvested and once recipient aortic arch and pulmonary arterial branches are extensively mobilized.

In patients with situs inversus, the pulmonary atrium (and the pulmonary veins) are midline structures [5]. This makes reconstruction of the pulmonary atrium not really difficult. As suggested by the Loma Linda group, the donor graft can be prepared by oversewing the left pulmonary venous orifices and opening the left atrium vertically between the superior and inferior right pulmonary veins. This maneuver helps juxtaposing donor and recipient pulmonary atria near the midline. In our experience, we found that creating two separate pulmonary venous cuffs and mobilizing the pulmonary veins make very easy the reimplantation of the pulmonary venous cuffs into the posterior wall of the donor left atrium.

Reconstruction of the mirror-image systemic venous inflow tracts actually represents the key to a successful operation. Several solutions may be adopted. Intraatrial baffles may be constructed using the systemic atrial wall to divert both venae cavae to the right side, thus allowing more or less ‘standard’ atrial anastomoses [3]. However, it is well known that intraatrial baffles are prone to late progressive obstruction and we think that extracardiac reconstruction is preferable, particularly in infants and young children.

The superior caval pathway can usually be reconstructed using the donor innominate vein. Sometimes (size discrepancy, insufficient length), the donor descending aorta may be interposed between the recipient superior vena cava and the graft right atrium [2]. The reconstructed superior caval pathway may be placed either anterior to the great arteries or posterior to the aorta in the transverse sinus [5]. This should be decided on a case by case basis according to the relative position of the great arteries and the systemic venous pathway. When the superior vena cava connection is placed anterior to the aorta, shortening the aortic reconstruction may be beneficial by preventing stretching or flattening of the venous pathway. By contrast, when the superior vena cava connection is placed behind the great arteries, it may be necessary to slightly lengthen the ascending aorta (with the donor aorta) to prevent any risk of posterior compression of the venous conduit.

Creating a tunnel which diverts the left sided orifice of the inferior vena cava to the right side allows approximation with the orifice of the graft inferior vena cava. Being constructed with autologous tissue (atrial wall superiorly and diaphragmatic pericardium inferiorly), this extracardiac conduit should retain growth potential. However, its complex anatomy and its position (between the diaphragm and the graft) expose to a potential risk of obstruction. It has been shown that there is usually adequate room for the conduit below the graft because of the size discrepancy between the pericardial sac and the donor organ and because the conduit location approximates the natural indentation of the atrioventricular groove [5]. However, this complex reconstruction needs careful follow-up evaluation. Should inferior vena cava obstruction occur, this could be relieved using percutaneous stenting procedures.

Finally, to achieve adequate positioning of the graft, the left pericardium must be widely opened and the apex of the heart placed in normal anatomic position. To prevent displacement of the heart to the right (with potential venous inflow obstruction), the pericardium can be attached to the anterior chest wall on the right side or a pericardial prosthetic mesh can be implanted.

	References

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1. Doty DB, Renlund DG, Caputo GR, Burton NA, Jones KW. Cardiac transplantation in situs inversus. J Thorac Cardiovasc Surg 1990;99:493–499.[Abstract]
2. Vouhe PR, Tamisier D, Le Bidois J, Sidi D, Mauriat P, Pouard P, Lefebvre D, Albanese SB, Khoury W, Kachaner J. Pediatric cardiac transplantation for congenital heart defects: surgical considerations and results. Ann Thorac Surg 1993;56:1239–1247.[Abstract]
3. Michler RE, Sandhu AA. Novel approach for orthotopic heart transplantation in visceroatrial situs inversus. Ann Thorac Surg 1995;60:194–197.[Abstract/Free Full Text]
4. Rubay JE, d'Udekem Y, Sluysmans T, Ponlot R, Jacquet L, de Leval MR. Orthotopic heart transplantation in situs inversus. Ann Thorac Surg 1995;60:460–462.[Abstract/Free Full Text]
5. Vricella LA, Razzouk AJ, Gundry SR, Larsen RL, Kuhn MA, Bailey LL. Heart transplantation in infants and children with situs inversus. J Thorac Cardiovasc Surg 1998;116:82–89.[Abstract/Free Full Text]