Volume 13, Issue 2 , Pages 91-100, Summer 2008
Fenestrated Right Ventricular Exclusion (Starnes' Procedure) for Severe Neonatal Ebstein's Anomaly
Article Outline
Ebstein's anomaly is characterized by malformation of the tricuspid valve, right ventricle, and right atrium. On the whole, Ebstein's anomaly is rare, occurring in 1:200,000 live births. Manifestation of the spectrum of malformation can be from the asymptomatic patient to the neonate in extremis on maximal support. Severely symptomatic neonates generally present with a “wall-to-wall” heart on chest radiograph due to massive right atrial and atrialized right ventricular dilation. Such neonates generally have variable amounts of right ventricular outflow tract obstruction with a high incidence of anatomic or physiologic pulmonary atresia. They require intensive preoperative support for biventricular failure. Preoperative treatment consists of mechanical ventilation, prostaglandin therapy, and moderate- to high-dose inotropic support. Historically, neonatal intervention for this anomaly was unsuccessful, generally resulting in mortality.
In 1987, Starnes and coworkers first successfully used a single ventricle approach to palliate the severely symptomatic neonate with Ebstein's anomaly.1 This approach involved exclusion of the malformed right ventricle with a glutaraldehyde-fixed autologous pericardial patch sewn at the “anatomic” level of the tricuspid valve annulus. Pulmonary blood flow was provided by a systemic to pulmonary artery shunt. Over time, this procedure evolved to include a fenestration in the pericardial patch. The evolution of the right ventricular exclusion has focused on decompression of the malformed right ventricle. Maneuvers such as keeping the coronary sinus on the atrial side of the patch and interrupting any pulmonary insufficiency are paramount to effective decompression of the excluded right ventricle.
It appears that effective decompression of the abnormal right ventricle has a significant effect on the systemic left ventricle as well. Following right ventricular exclusion, we have noted that the septal impingement that occurs in these massively dilated hearts is ameliorated and that the systemic ventricle returns to the globular shape seen in the normal heart. This ventriculo–ventricular interaction is the reason that simply providing pulmonary blood flow alone has no significant effect on the patient survival.
The goals of this procedure are as follows: to exclude and decompress the malformed right ventricle; to assure an uninterrupted atrial communication; to perform a reduction atrioplasty; and to provide pulmonary blood flow via a systemic to pulmonary shunt.
Operative Technique
Figure 1.
Schematic representation of a four-chamber echocardiographic view of an Ebsteinoid heart. Outlined in dashed lines is the massively enlarged right atrium (RA) and atrialized right ventricle (RV). The remainder of the unaffected heart, the trabeculated right ventricle, the left ventricle (LV), and the left atrium (LA), is represented by the dotted lines. Notable is the downward displacement of the tricuspid valve and the relative sizes of the affected anatomy. Represented is the Great Ormond Street (GOS) equation popularized by Celermajer and coworkers.2 The equation is the ratio of the “affected” portions of the heart over the denominator, represented by the “unaffected” portions of the heart. Historically, ratios approaching 1.0 have been shown to predict nearly 100% mortality. S = superior; L = left; I = inferior; R = right.
Figure 2.
(A) Neonates who are candidates for the right ventricular exclusion, or Starnes procedure, are universally ventilated and on inotropic and nitric oxide support. Patients are placed supine for standard sternotomy incision. A full sternotomy is advocated due to the size of the affected heart. Thymectomy is performed. As demonstrated, the right atrial appendage is overwhelming and usually obstructing surgical access to the great vessels. A traction suture is generally placed for cannulation purposes. RA = right atrium; LV = left ventricle. (B) At the time of pericardiotomy, a large portion of anterior pericardium is harvested for right ventricular exclusion. Care must be taken to avoid traction or mechanical injury to the phrenic nerve. The neurovascular bundle can be distorted anteriorly secondary to the massive dilation of the cardiac structures and associated pericardium. The remainder of the pericardium is opened in a stellate fashion in order to form a pericardial well. Ao = aorta; MPA = main pulmonary artery.
Figure 3.
Cannulation is generally single aortic in the distal ascending aorta, and bicaval in the superior vena cava (SVC) and inferior vena cava (IVC), respectively. Maneuvers to help with exposure are, again, traction of the right atrial appendage and incision of the pericardial investment over the SVC for simpler cannulation. In some instances, the right atrial expansion is so dramatic that a single cannula is first placed; bypass is commenced, and later bicaval cannulation is performed in a more controlled manner. Infrequently, the SVC is very small, or if bilateral SVC are present, a single venous cannula is used and a brief period of circulatory arrest is utilized for right ventricular exclusion and atrial septectomy. Cardiopulmonary bypass is initiated and the patent ductus arteriosus is controlled and occluded. The patient is cooled to 28°C. The cross-clamp is applied and cold blood cardioplegia is given down the root. Characterized is the line of excision for reduction atrioplasty. The lateral incision should allow simple linear closure without undue tension on the cavae. The medial portion of the atriotomy is more difficult to define due to the distorted anatomy associated with the atrialized portion of the right ventricle. The atrioventricular groove and right coronary artery may be compromised by incision or subsequent closure. This should be guarded against by having a safe margin of atrial cuff for closure. Ao = aorta; MPA = main pulmonary artery; RV = right ventricle.
Figure 4.
(A) After reduction atrioplasty, exposure is provided by triangulating stay sutures. As pictured, the tricuspid orifice is unguarded with a large “sail-like” anterior leaflet usually fixed to the septum, and in varying degrees obstructing the right ventricular outflow tract. Failure of delamination leaves the septal and posterior leaflets small and inferiorly displaced, with essentially no function. The internal anatomy must be evaluated and identified, due to the distortion observed in the Ebsteinoid heart. First, the “anatomic” annulus can be identified by ventral traction on the atrial free edge. This maneuver will allow the surgeon to identify the atrioventricular (AV) groove for patch placement. Next, the coronary sinus is clearly identified by the administration of cardioplegia. Last, free atrial communication is assured by complete septectomy. A = anterior; AV = atrioventricular; CS = coronary sinus. (B) The lateral schematic of the Ebsteinoid heart. Notable is the large anterior leaflet with multiple fusions with the ventricular septum, causing right ventricular outflow tract obstruction. LV = left ventricle; MPA = main pulmonary artery; RA = right artery; RV = right ventricle; TV = tricuspid valve.
Figure 5.
Fixed autologous pericardium is cut to approximate the size of the “anatomic” annulus represented by the atrioventricular (AV) groove. The patch is sewn in a running fashion with a monofilament suture. Care should be taken to avoid deep bites or purse-stringing of the AV groove. Interval external examination should be used to avoid right coronary artery distortion. The ostium of the coronary sinus should remain on the atrial side of the patch. Sutures should avoid the mouth of the sinus, as pathologic studies have determined that the AV node may be displaced toward the ostium in Ebsteinoid hearts.
Figure 6.
Fenestration of the patch is performed with a 4-mm punch. This fenestration serves to completely decompress the excluded right ventricle, should any Thebesian venous drainage empty into the right heart.
Figure 7.
Atriotomy closure is completed in a linear fashion protecting the atrioventricular (AV) groove. In unusual circumstances, the pulmonary valve is regurgitant. In this special circumstance, the pulmonary artery must be interrupted. If the pulmonary valve (as pictured) is of near normal caliber with moving leaflets, formal pulmonary artery division and pulmonary valve over-sewing are appropriate. If the valve is diminutive and rudimentary, a single proximal hemoclip may be applied. MPA = main pulmonary artery.
Figure 8.
Pulmonary blood flow is provided by a systemic to pulmonary artery shunt. As pictured, a 3.5-mm Gore-Tex shunt is fashioned from the innominate artery to the right pulmonary artery. This portion of the procedure is performed during the rewarming period. Patients are weaned from bypass generally on inotropic support and nitric oxide therapy. Aspirin is administered in the postoperative setting for shunt patency. B-T = Blalock Taussig.
Conclusions
Since 1992, 24 neonates have undergone palliation for severe, symptomatic Ebstein's anomaly at our institution.3 To date, we have observed 19 long-term survivors with 5 in-hospital deaths. Over 50% of patients demonstrated severe pulmonary stenosis or atresia. All patients failed medical therapy and were taken to the operating room for overt biventricular failure with or without prostaglandin dependence.
Currently, all survivors have undergone, or are awaiting, bidirectional cavopulmonary shunt, at a mean of 6 months. Over half of the patients have gone on to a completion Fontan procedure. To date, all patients have had suitable hemodynamics for further palliation. No interstage mortality has been observed.
After initial palliation, the right ventricle undergoes involution and demonstrates significant regression when measured by computed tomographic ratio, Great Ormond Street ratio, and right ventricle to left ventricle ratio.4 Furthermore, the morphology and function of the systemic left ventricle normalizes by the time of the second-stage bidirectional Glenn. To date, only 2 of 24 patients have required pulmonary valve interruption.
The fenestrated right ventricular exclusion serves as an excellent palliative procedure in a very difficult patient population. Due to the rarity of the condition and the relatively recent conception of right ventricle exclusion, long-term follow-up data are not available.
References
- Ebstein's anomaly appearing in the neonate (A new surgical approach). J Thorac Cardiovasc Surg. 1991;101:1082–1087
- Ebstein's anomaly: presentation and outcome from fetus to adult. J Am Coll Cardiol. 1994;23:170–176
- Current surgical therapy for Ebstein's anomaly in neonates. J Thorac Cardiovasc Surg. 2006;132:1285–1290
- Fate of the right ventricle after fenestrated right ventricular exclusion for severe neonatal Ebstein anomaly. J Thorac Cardiovasc Surg. 2007;134:1406–1410discussion 1410-1412
PII: S1522-2942(08)00030-5
doi:10.1053/j.optechstcvs.2008.03.002
© 2008 Elsevier Inc. All rights reserved.
Volume 13, Issue 2 , Pages 91-100, Summer 2008
