MMCTS
(December 17, 2007). doi:10.1510/mmcts.2007.002733
Copyright © 2007 European Association for Cardio-thoracic Surgery
Procedure
Surgical approach to hyploplastic left heart syndrome – Norwood Stage I
Evelio Rodriguez,
Mamdouh Al-Ahmadi and
Thomas L. Spray*
Children's Hospital of Philadelphia, Philadelphia, PA, USA
* Corresponding author: * 34th Street and Civic Center Boulevard, Suite 8527, Philadelphia, PA 19104-4399, USA. Tel.: +1-215-590 2708; fax: +1-215-590 2715 spray{at}email.chop.edu
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Summary
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Hypoplastic left heart syndrome (HLHS) is characterized by left ventricular and ascending aorta hypoplasia. The treatment of this condition usually involves three surgical stages beginning with the Norwood Stage I operation and culminating in the Fontan–Kreutzer procedure with an intermediate cavopulmonary shunt. We will illustrate our current surgical approach for the Norwood Stage I reconstructive procedure.
Key Words: Damus–Kaye–Stansel • HLHS • Hypoplastic left heart syndrome • Norwood operation • Sano modification • Single ventricle
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Introduction
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Hypoplastic left heart syndrome (HLHS) represents 5% of all congenital heart disease and is responsible for 25% of cardiac deaths in the first week of life. Schematic 1 illustrates the anatomic features and representative hemodynamic parameters for unrepaired HLHS.
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Schematic 1 Anatomic and hemodynamic features of unrepaired left heart syndrome. Saturation depends on pulmonary venous return crossing the atrial septum to mix with systemic return. Systemic cardiac output is dependent on patent ductus arteriosus. (Reproduced from Kaiser LR, Kron IL, Spray TL. Mastery of cardiothoracic surgery, 2nd edition. Lippincott Williams & Wilkins, 2006, Chapter 93, pages 935–946, by permission of Lippincott Williams & Wilkins.)
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Before the 1980s, HLHS was uniformly a lethal condition. In 1980, William Norwood first achieved successful palliation in infants and later in 1983 he reported the first staged successful approach culminating in a Fontan repair [1]. The purpose of this chapter is to illustrate our initial management of these complex patients and the technical aspects of the Stage I reconstruction using the modified Blalock-Taussig (BT) shunt or the Sano modification (RV-PA shunt) for pulmonary artery inflow.
Initial management
If HLHS is discovered during prenatal ultrasound, arrangements should be made for prompt transfer upon delivery to a facility with expertise in the management of this condition. In the event of suspected intact or restrictive atrial septum with HLHS, high-risk term delivery via C-section should be scheduled at a facility where a safe and expeditious atrial septectomy could be accomplished.
After delivery, prostaglandin E1 is started and upon arrival to our institution an echocardiogram is obtained to confirm the diagnosis of HLHS. In addition, a head ultrasound is obtained to rule out intracranial hemorrhage that could worsen during cardiopulmonary bypass. Patients with a suspicion of medical necrotizing enterocolitis who remain hemodynamically stable should have a 7-day course of intravenous antibiotics. Umbilical arterial and venous lines are used for central access and hemodynamic monitoring. Most infants do not require endotracheal intubation and supplemental oxygen should be limited since it can decrease pulmonary vascular resistance, and increase the pulmonary to systemic flow ratio and thus decrease systemic perfusion. The patient is usually taken to the operating room between days of life two to four. Once in the operating room, nasotracheal intubation is performed and the child is ventilated on room air.
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Surgical technique
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The primary goals of the Stage I procedure are: (1) to create an unrestrictive interatrial communication to provide complete mixing and avoid pulmonary venous congestion, (2) provide unobstructed outflow from the ventricle to the systemic circulation, and (3) to establish a reliable but controlled source of pulmonary blood flow.
The heart is exposed via a median sternotomy, the thymus is removed and the pericardium is opened. The mediastinum is inspected to corroborate the echocardiogram findings, with special attention to identify abnormalities of the aortic arch and coronary arteries (Video 1).
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Video 1 Extensive mobilization of the ascending and descending aorta, head vessels, ductus arteriosus, and pulmonary arteries with careful identification of the recurrent and phrenic nerves is performed. Tourniquets are passed around the right and left pulmonary arteries and arch branches, except for the innominate artery, since the proximal BT shunt anastomosis is performed during the cooling period of cardiopulmonary bypass. We prefer to use the Sano modification (RV-PA shunt) if an aberrant right subclavian artery is present or if the innominate artery is small.
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Pursestring sutures are then placed in the proximal main pulmonary artery below the origin of the branch pulmonary arteries and generously around the right atrial appendage in order to facilitate exposure for the atrial septectomy (Schematic 2).
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Schematic 2 After heparinization, the pulmonary artery and the right atrium are cannulated and cardiopulmonary bypass is commenced. The right and left pulmonary artery tourniquets are tightened to prevent pulmonary steal from the systemic circulation. AO=aorta; DA=ductus arteriosus; MPA=main pulmonary artery; RA=right atrium. (Reproduced from Gardner TJ, Spray TL. Operative cardiac surgery, fifth edition. Hodder Headline Group/Arnold Publishers, 2004, Chapter 59, pages 861–877, by permission of Edward Arnold (Publishers) Ltd.)
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Once cardiopulmonary bypass is initiated, systemic cooling is performed for at least 15 min to a nasopharyngeal temperature of 18 °C. During this time the BT shunt and pulmonary homograft hemi patch are prepared (Video 2).
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Video 2 The proximal end of a polytetrafluoroethylene (PTFE) tube graft (4.0 mm for patients >3.2 kg and 3.5 mm for smaller infants) is cut diagonally in preparation for the BT shunt. It is best to cut the shunt to the appropriate length prior to decompression of the heart. A previously thawed pulmonary homograft patch is then trimmed in an extended arrowhead shape and set aside.
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The BT shunt is constructed next after a partial occluding clamp is applied on the proximal portion of the innominate artery (Video 3).
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Video 3 The proximal anastomosis is then performed to a longitudinal arteriotomy in the inferior aspect of the artery using a running 7-0 monofilament suture. Once completed, the vascular clamp is released and flow through the shunt is assessed. The shunt is then controlled with a hemoclip during the reminder of the procedure. A tourniquet is then placed around the innominate artery in preparation for circulatory arrest.
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The cardioplegia line is connected to a side arm of the arterial cannula. After the patient is cooled to 18 °C over 15–20 min, circulatory arrest is initiated, the tourniquets on the arch vessels are tightened, and a vascular clamp is placed on the descending thoracic aorta distal to the ductal insertion site. The cardiŠ¾plegia can then be injected retrograde through the aortic cannula and the ductus into the ascending aorta to provide diastolic cardiac arrest. Then the arterial and venous cannulas, pulmonary artery tourniquets, and the aortic clamp are removed. The ductus is ligated and divided distally on the aortic end.
The atrial septectomy is performed next (Schematic 3).
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Schematic 3 Working through the atrial pursestring suture, the atrial septum can be widely excised. However, if the exposure is limited, a right atriotomy incision is made and the septum primum, which is commonly displaced to the left, is excised to create a widely unobstructed atrial communication. If necessary the coronary sinus is unroofed into the left atrium to ensure a completely unrestrictive atrial defect. (Reproduced from Gardner TJ, Spray TL. Operative cardiac surgery, fifth edition. Hodder Headline Group/Arnold Publishers, 2004, Chapter 59, pages 861–877, by permission of Edward Arnold (Publishers) Ltd.)
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The pulmonary artery is then divided and closed (Video 4).
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Video 4 The pulmonary artery is divided at the origin of the right pulmonary artery. This incision leaves slightly more pulmonary artery on the left side and thus ensures that the connection between the proximal pulmonary artery and the aorta is high enough to avoid sewing near the coronary artery origin from the diminutive ascending aorta. The bifurcation of the pulmonary arteries is then closed primarily in a vertical fashion; however, if the caliber of the pulmonary arteries is small, the bifurcation is closed with an oval shaped pulmonary homograft patch using a running monofilament suture in order to prevent stenosis.
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The distal BT shunt anastomosis is then created (Video 5).
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Video 5 The distal BT shunt anastomosis is constructed to the origin of the right pulmonary artery with a 7-0 monofilament suture. This technique permits the BT shunt to be connected more medially behind the neoaorta prior to its reperfusion making the exposure easier. Meticulous shunt creation is an important part of the operation to avoid cyanosis or shunt thrombosis.
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After completion of the BT shunt, the aortic reconstruction is performed (Videos 6, 7, 8, 9). The completed aortic reconstruction is depicted in Schematic 4.
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Video 6 An incision is made on the medial aspect of the diminutive ascending aorta immediately adjacent to the divided main pulmonary artery. The incision is carried superiorly along the undersurface of the aortic arch through the ductal insertion site to a point at least 1 cm distal to the ductal insertion in the descending thoracic aorta. The ductal tissue is excised completely. The ridge of coarctation tissue is excised if present, and if severe coarctation with much adjacent ductal tissue is present, the coarctation segment is excised and the back wall of the arch is anastomosed to the descending thoracic aorta.
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Video 7 The proximal pulmonary artery is then sutured carefully to the diminutive ascending aorta, in a Damus–Kaye–Stansel (DKS) fashion, with interrupted 7-0 monofilament sutures. It must be assured that no restriction of inflow into the coronary is present. Mobilization of the tissues between the aorta and the pulmonary artery is done so that the epicardium does not potentially kink the origin of the coronary arteries when the neoaorta expands. Occasionally, a cutback in the adjacent sinus of the pulmonary artery is necessary to prevent compression of the aorta and allow adequate coronary inflow.
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Video 8 The aorta is then augmented with the previously prepared pulmonary homograft patch. The tailoring of the patch geometry is complex. Care must be taken to avoid a patch so redundant that it may cause twisting under systemic pressure resulting in either impingement on the origin on the innominate artery with limitation of inflow to the BT shunt or the head vessels or twisting in the descending aorta causing distal arch obstruction. In general, making the patch too narrow rather than too wide is preferable. The suture line is started distally with a 7-0 monofilament suture and brought to the undersurface of the arch just proximal to the origin of the innominate artery.
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Video 9 The excess patch that will be sewn to the anterior and posterior wall of the native diminutive ascending aorta is excised. The posterior part of the pathway is in general shorter than the anterior portion. The portion of the patch that will be sewn to the pulmonary artery is tailored so as to be concave (shorter posterior than anterior). The suture line is then completed. The arch is infused with cold saline solution to assess the geometry of the arch and rule out any kinking or residual obstruction.
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Schematic 4 The completed aortic reconstruction. (Reproduced from Gardner TJ, Spray TL. Operative cardiac surgery, fifth edition. Hodder Headline Group/Arnold Publishers, 2004, Chapter 59, pages 861–877, by permission of Edward Arnold (Publishers) Ltd.)
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Sano (RV-PA) modification
The Sano conduit is prepared after the initiation of cardiopulmonary bypass and during the cooling phase (Video 10).
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Video 10 A 5 mm PTFE graft and a thin PTFE patch are selected. Then a 5 mm punch hole is made in the middle of the PTFE patch. The tube graft is passed through the patch for a distance of 5 mm. The patch is sewn to the side of the tube graft, and then is trimmed to size.
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The pulmonary artery is divided transversely at the origin of the right pulmonary artery as previously shown in Video 4. However, the pulmonary artery bifurcation is only partially closed from the bottom up (Schematic 5).
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Schematic 5 The pulmonary artery confluence is only partially closed from the bottom up in order to allow the Sano conduit to sit on the superior aspect of the pulmonary artery in order to avoid kinking of the conduit. (Reproduced from Gardner TJ, Spray TL. Operative cardiac surgery, fifth edition. Hodder Headline Group/Arnold Publishers, 2004, Chapter 59, pages 861–877, by permission of Edward Arnold (Publishers) Ltd.)
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Once the aortic reconstruction is completed the distal and proximal Sano anastomoses are constructed (Videos 11 and 12).
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Video 11 The distal end of tube graft is anastomosed to the remainder of the pulmonary artery bifurcation. This brings the entrance of the shunt anteriorly into the pulmonary bifurcation to avoid interference with the constructed neoaorta, and to allow for growth of the pulmonary bifurcation.
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Video 12 A ventriculotomy is made several millimeters below the neoaortic valve using a #11 blade and a 5 mm punch. Residual muscle on the inside of the ventriculotomy is trimmed further with the punch or the blade. The edge of the patch is sewn to the edge of the ventriculotomy starting at 12 o'clock. A counter stitch is placed at six o'clock and tied, ensuring that the proximal end of the tube graft will sit inside the ventriculotomy and stent it open. The suture line is then completed to the epicardium. Ringed Gortex graft without a proximal patch can also be used.
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The patient is then placed on cardiopulmonary bypass and rewarmed. After weaning off cardiopulmonary bypass the patient undergoes modified ultrafiltration and the chest is routinely closed.
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Results
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The hospital survival after the Stage I operation for HLHS at the Children's Hospital of Philadelphia has improved throughout different eras: 56.2% (1984–1989), 64.7% (1989–1991), 67.6% (1992–1994), 71.3% (1995–1998), and 85% (2002–2004) [2, 3]. More recently, survival has approached 93% in some subsets of patient anatomy [4]. At the Hospital for Sick Children in Toronto, survival improved from 41% from 1990 through 1993 to 61% from 1994 through 1997 and 82% from 1998 to 2000 [5]. Similar results have been shown at Children's Hospital of Wisconsin, University of Michigan and Birmingham Children's Hospital in the UK [6, 7].
Although not consistent among different series, several risk factors have been associated with increased mortality after Stage I operation for HLHS. These risk factors include: noncardiac/genetic anomalies, low birth weight (<2.5 kg), association with other cardiac anomalies (e.g. total anomalous pulmonary venous return) severe atrioventricular valve regurgitation, preoperative right ventricular dysfunction, prolonged deep hypothermic circulatory arrest, and size of ascending aorta among others [2, 6, 7, 8, 9]. In addition, several reports have suggested improved survival in patients undergoing the Sano modification when compared to patients undergoing BT shunts [4, 6]. There is an ongoing multi-institutional, prospective, randomized study comparing BT shunts versus the Sano modification in the United States. Approximately half of the patients required for the study have been accrued and once the study is completed we may have a better sense of the impact of the source of pulmonary blood flow on survival after the Stage I procedure.
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Discussion
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HLHS is a commonly encountered anomaly for congenital cardiac surgeons. The Norwood procedure revolutionized the management of a previously uniformly lethal condition into one with an 85–90% survival after Stage I reconstruction. Further refinements in surgical technique, including different sources of pulmonary inflow may improve outcomes. In addition, certain groups of patients with unfavorable prognostic factors (e.g. very low birth weight, chromosomal abnormalities, and total anomalous pulmonary venous return) may benefit from other types of intervention instead of a Stage I operation, such as heart transplantation or initial hybrid procedure with pulmonary artery banding and stenting of the atrial septum and ductus arteriosus.
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References
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- Norwood WI, Lang P, Hansen DD. Physiologic repair of aortic atresia-hypoplastic left heart syndrome. New Engl J Med 1983;308:23–26.[Medline]
- Mahle WT, Spray TL, Wernovsky G, Gaynor JW, Clark BJ 3rd. Survival after reconstructive surgery for hypoplastic left heart syndrome: A 15-year experience from a single institution. Circulation 2000;102:III136–141.[Medline]
- Tabbutt S, Dominguez TE, Ravishankar C, Marino BS, Gruber PJ, Wernovsky G, Gaynor JW, Nicolson SC, Spray TL. Outcomes after the stage I reconstruction comparing the right ventricular to pulmonary artery conduit with the modified Blalock Taussig shunt. Ann Thorac Surg 2005;80:1582–1590; discussion 1590–1591.[Abstract/Free Full Text]
- Pizarro C, Mroczek T, Malec E, Norwood WI. Right ventricle to pulmonary artery conduit reduces interim mortality after stage 1 Norwood for hypoplastic left heart syndrome. Ann Thorac Surg 2004;78:1959–1963; discussion 1963–1964.[Abstract/Free Full Text]
- Azakie A, Merklinger SL, McCrindle BW, Van Arsdell GS, Lee KJ, Benson LN, Coles JG, Williams WG. Evolving strategies and improving outcomes of the modified Norwood procedure: a 10-year single-institution experience. Ann Thorac Surg 2001;72:1349–1353.[Abstract/Free Full Text]
- McGuirk SP, Stickley J, Griselli M, Stumper OF, Laker SJ, Barron DJ, Brawn WJ. Risk assessment and early outcome following the Norwood procedure for hypoplastic left heart syndrome. Eur J Cardiothorac Surg 2006;29:675–681.[Abstract/Free Full Text]
- Stasik CN, Goldberg CS, Bove EL, Devaney EJ, Ohye RG. Current outcomes and risk factors for the Norwood procedure. J Thorac Cardiovasc Surg 2006;131:412–417.[Abstract/Free Full Text]
- Gaynor JW, Collins MH, Rychik J, Gaughan JP, Spray TL. Long-term outcome of infants with single ventricle and total anomalous pulmonary venous connection. J Thorac Cardiovasc Surg 1999;117:506–513; discussion 513–514.[Abstract/Free Full Text]
- Gaynor JW, Mahle WT, Cohen MI, Ittenbach RF, DeCampli WM, Steven JM, Nicolson SC, Spray TL. Risk factors for mortality after the Norwood procedure. Eur J Cardiothorac Surg 2002;22:82–89.[Abstract/Free Full Text]
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Summary
Introduction