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J Thorac Cardiovasc Surg 2007;133:1303-1310
© 2007 The American Association for Thoracic Surgery
Surgery for Congenital Heart Disease |
a Division of Cardiovascular Surgery, Mayo Clinic and Foundation, Rochester, Minn
b Division of Pediatric Cardiology, Mayo Clinic and Foundation, Rochester, Minn
c Division of Cardiovascular Diseases, Mayo Clinic and Foundation, Rochester, Minn.
Read at the Thirty-second Annual Meeting of the Western Thoracic Surgical Association, Sun Valley, Idaho, June 21-24, 2006.
Received for publication June 18, 2006; revisions received December 4, 2006; accepted for publication December 18, 2006. * Address for reprints: Joseph A. Dearani, MD, Division of Cardiovascular Surgery, Mayo Clinic College of Medicine, 200 First St, SW, Rochester, MN 55905. (Email: jdearani{at}mayo.edu).
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Abstract |
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Methods: Between July 1999 and March 2006, 169 patients underwent operations to repair Ebstein anomaly. Fourteen patients had a bidirectional cavopulmonary shunt constructed. The median age at operation was 6 years (17 months-57.8 years). All of the patients had severe Ebstein anomaly with dilated right-sided chambers and/or right ventricular dysfunction. The mean left ventricular ejection fraction was 54.5% (range 35%–72%). Three patients were initially referred for heart transplantation, and the bidirectional cavopulmonary shunt allowed a conventional repair.
Results: Procedures included bidirectional cavopulmonary shunting (14), tricuspid valve replacement (11), tricuspid valve repair (2), and right ventricular resection (3). Shunting was planned preoperatively in 9 patients; the indication in 5 other patients was hemodynamic instability after separation from cardiopulmonary bypass. One patient died of multiple organ failure. Median follow-up in 10 patients was 18 months (3 months-6.5 years). The preoperative left ventricular ejection fraction of less than 50% improved in 3 patients to greater than 50% postoperatively.
Conclusions: The 1.5-ventricle repair can be utilized in patients with severe Ebstein anomaly and impaired right ventricular function who are at high risk for surgical treatment. We believe the bidirectional cavopulmonary shunt may be considered as a planned procedure, as an intraoperative salvage maneuver, or as an alternative to cardiac transplantation in selected patients.
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionStudy LimitationsConclusionsReferences |
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The bidirectional cavopulmonary shunt (BCPS), or "one and one-half (1.5) ventricle repair" has been used when the RV was judged not capable of supporting the pulmonary circulation.1,2
Diversion of the superior vena caval blood to the pulmonary arteries reduces the RV preload, and this may decrease RV work.1 In patients with Ebstein anomaly and impaired RV function, the BCPS may facilitate surgical treatment by unloading the RV and providing preload to the LV. The 1.5-ventricle repair may be an alternative for patients with severe Ebstein anomaly and an impaired RV who are at high risk for standard surgical treatment.
The purpose of this report was to review our institutional experience with the surgical treatment of patients with Ebstein anomaly and an impaired RV who had a BCPS as part of their repair.
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Materials and Methods |
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From July 1, 1999 to March 30, 2006, 169 patients with Ebstein anomaly underwent surgical treatment; 14 of these had a BCPS and form the cohort of this study. Their medical records were reviewed. Eight of the 14 operations were performed in the last 12 months of the review period. There were 10 male and 4 female patients, and their ages ranged from 17 months to 57.8 years (mean 16.9 years; median 6 years).
The youngest patient (17 months) was in shock owing to biventricular failure; RV enlargement resulted in LV failure because of inadequate preload and significant compression from the massive RV. In the younger group of patients (patients 2 through 10, Table 1), whose ages ranged from 18 months to 12.8 years, the most common presentation was cyanosis, fatigue, or decreased stamina. Two children (patients 3 and 8) were free of symptoms. Dyspnea was the predominant clinical presentation in the adult age group.
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Prior operations had been performed elsewhere in 4 patients. Patients 2 and 3 were implanted with modified Blalock–Taussig shunts as infants, and 1 child (patient 4) had undergone a TV repair and modified maze procedure. One adult (patient 11) had a TV replacement and atrial septal defect closure as a teenager.
Preoperative diagnostic testing included chest radiography, electrocardiography, and comprehensive transthoracic echocardiographic-Doppler examination in all patients. Echocardiography was used to confirm the diagnosis of Ebstein anomaly and to determine RV and LV size and function, the degree of TV regurgitation, and the potential for TV repair. Hemodynamic cardiac catheterization was performed selectively.
All patients had anatomically severe Ebstein anomaly with significant abnormalities and displacement of the TV. Severe RV dilation and dysfunction were present in 11 patients. Two patients had only moderate RV dilation but severe RV dysfunction. In these 13 patients, the RV fractional area change was 19% (range 13%-29%). One child had hypoplasia of the anatomic RV with moderate RV dysfunction (fractional area change of 37%). TV regurgitation was graded as severe in 12, moderate in 1, and mild in 1. Patient 3 had an atrial septal defect and severe RV enlargement but only mild TV regurgitation. Patient 8 had progressive RV enlargement and severe TV regurgitation.
The mean LV ejection fraction (LVEF) was 54% (range 35%-72%) and the mean LV fractional area change was 45% (range 22%-58%). In patient 1, the LVEF could not be estimated because of limited echocardiographic views as the LV was underfilled and compressed by the RV. Three patients (patients 10, 12, and 14) had an LVEF of less than 50%. Patient 11 initially had a depressed LVEF; however, after his medication regimen was adjusted and the ventricular response to his atrial tachyarrythmias was controlled, his preoperative LVEF improved significantly. Patient 12 had a preoperative hemodynamic catheterization; his mean pulmonary artery pressure (PAP) was 27 mm Hg and his pulmonary capillary wedge pressure was 24 mm Hg, resulting in a transpulmonary gradient of 3 mm Hg.
Operative Technique
Standard surgical techniques of sternotomy, aortic and bicaval cannulations, cardiopulmonary bypass, and myocardial protection were used. All extracardiac shunts were interrupted. Closure of interatrial communications was either by direct suture or by autologous pericardial patch. Maze procedures and their modifications were performed in patients (n = 3) with a history of atrial tachyarrhythmias using techniques previously described.3 The inferior wall of the RV was resected (n = 3) when it was noted to be thin, transparent, and dyskinetic. The resection included an ellipse from the base to the apex; this effectively brought the acute margin of the RV closer to the posterior descending coronary artery. Right reduction atrioplasty was routinely performed. When a TV replacement was done (n = 11), the conduction tissue and right coronary artery were protected.4 All valve replacements in this series were performed with stented porcine bioprostheses. TV repair techniques with modifications have been described previously.5 The BCPS (n = 14) was performed by division of the superior vena cava at the junction with the right atrium followed by an end-to-side anastomosis to the superior surface of the right pulmonary artery; the azygos vein was routinely divided.
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Results |
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In 9 patients, the potential need for a BCPS was mentioned in the preoperative record and reflected concerns about RV dysfunction. These were referred to as "planned" procedures. In the other 5 patients, the BCPS was performed as a salvage procedure owing to RV failure.
In patients with a normal LVEF, intraoperative left atrial pressures or PAPs were not routinely measured. Nevertheless, patients 2 and 11 had an average left atrial pressure of 4 mm Hg and patient 13 had a mean PAP of 16 mm Hg. In patients with depressed LVEF, these pressures were measured intraoperatively to confirm that the patient would tolerate the BCPS. Patients 10, 12, and 14 had a mean left atrial pressure of 7 mm Hg, a mean PAP of 15 mm Hg, and a mean transpulmonary gradient of 7 mm Hg.
Five patients had delayed sternal closure, 2 children required extracorporeal membrane oxygenator support, and 2 adults required intra-aortic balloon counterpulsation (Table 2). One patient required dialysis. One child required a thrombectomy of the TV bioprosthesis at the time of removal of extracorporeal membrane oxygenator support. One patient required a permanent epicardial pacing system for complete heart block.
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In all 3 patients with preoperative LVEF less than 50%, the postoperative LVEF at hospital dismissal was greater than 50%.
The length of stay after the initial operation ranged from 4 to 28 days (mean 9.8 days; median 7.5 days). Follow-up after hospital dismissal was available in 10 patients. This ranged from 3 months to 6.5 years (mean 25 months; median 18 months). Nine patients reported no functional limitations at the time of their last follow-up. One patient (patient 14) reported a significant improvement since surgery, although still having dyspnea when not receiving diuretic therapy. Patients 8 and 9 reported upper extremity and facial swelling, but this was not problematic.
Echocardiographic follow-up was available in 4 patients (mean 11 months; range 6-15 months). In 3 patients, the RV and LV functions did not deteriorate or improve. Only 1 patient (patient 14) had a significant improvement in LVEF from 40% to 60%, yet a significant deterioration in RV fractional area change from 16% to 6%. This patient remains symptomatic.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionStudy LimitationsConclusionsReferences |
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The BCPS may be beneficial in patients undergoing surgical interventions for congenital heart lesions when hemodynamic performance is compromised by a failing pulmonary ventricle.2 Postoperative RV failure is associated with increased early mortality in surgically treated patients with Ebstein anomaly,7 and an enlarged heart is also a risk factor for mortality.8 Chauvaud and associates7 and Chauvaud9 believe that the addition of a BCPS to the surgical treatment of patients at risk of RV failure decreases operative mortality. The BCPS accomplishes two important things in the setting of RV failure: (1) it reduces the venous return to the enlarged, dysfunctional RV and (2) it optimizes preload to the LV.
A small number of cases describing the use of a BCPS as an adjunct to the surgical treatment of Ebstein anomaly can be found within series of outcome analyses of the 1.5-ventricle repair or within series of the surgical treatments and outcomes of patients with Ebstein anomaly.1,10-14 However, little emphasis has been placed on the clinical or echocardiographic characteristics of these patients; the rationale for the construction of the BCPS is only mentioned briefly; and late outcomes have not been reported. There are few case series that exclusively report on the use of the BCPS with Ebstein anomaly.7,15,16
BCPS has been used infrequently in patients with Ebstein anomaly and has been used only recently at our institution. Since we have gained experience with the surgical management of Ebstein anomaly, we have considered the use of the BCPS as an adjunctive treatment for those patients who were considered to be at high risk for a conventional operation. In our experience, the overwhelming majority of patients with Ebstein malformation can have successful biventricular repair. We now use the BCPS selectively in the setting of a severely enlarged and/or severely dysfunctional RV. The BCPS is not performed routinely because it compromises access to the heart for electrophysiologic evaluation and ablation and for pacemaker lead placement, as seen in one of our patients. In addition, it may be associated with pulsations of the head and neck veins, facial suffusion, and the development of collateral veins and pulmonary arteriovenous fistulas.10
When a concomitant BCPS is performed at the time of TV replacement, blood flow through the TV is reduced. Therefore, it is important to place a TV prosthesis that is not oversized (ie, a valve that matches the reduced flow through the right side of the heart) so that all the bioprosthetic leaflets or mechanical discs open and close normally. Because we have occasionally noted decreased mobility of the leaflets of bioprosthetic valves after the BCPS, we now routinely anticoagulate with warfarin for a 3- to 6-month period or until full mobility of all leaflets is demonstrated on echocardiography. Aspirin, 81 mg daily, is continued thereafter. The increased risk of thrombosis and need for anticoagulation are potential disadvantages of a concomitant BCPS at repair of Ebstein anomaly.
Patients with Ebstein anomaly may have significant RV dysfunction from longstanding TV regurgitation superimposed on a myopathic ventricle.17 Consequently, when the RV is significantly enlarged in the setting of severe TV regurgitation, we believe it is important to reduce the regurgitation to no more than a mild or moderate degree after TV repair to prevent further RV dilatation or dysfunction and to optimize the possibility of favorable RV remodeling. If this result cannot be obtained, it is our philosophy to then proceed with TV replacement (usually porcine bioprosthesis) so that the volume load on the myopathic RV is as low as possible. In our experience, the late results of TV replacement are comparable with those of TV repair.4
Marianeschi and associates15 have suggested that the construction of a BCPS in patients with mild TV regurgitation may reduce the RV preload to a point where no intervention on the TV is required; patients with moderate or severe TV regurgitation may have reductions in the regurgitation that allow less aggressive TV interventions; and the BCPS may also allow more TV repair options that would result in iatrogenic TV stenosis in the absence of a BCPS. The creation of a BCPS may also decrease the incidence of reoperation for patients with residual TV regurgitation.14 There are insufficient data at the present time to confirm the validity of these concepts. Nevertheless, we favor sending the patient out of the operating room with a competent TV.
Ventricular plication has often been performed during repair of Ebstein anomaly. Our original ventricular plication technique (apex to base) results in a maximal reduction of RV size, but appeared to be associated with increased ventricular rhythm disturbances.18 Currently, we reserve plication or resection for thin, transparent, or dyskinetic segments of the atrialized RV myocardium, most often seen in the area of the inferior wall of the RV. Potential advantages of plication or resection include a reduction in the size of the nonfunctional portion of the RV, which may improve the transit of blood through the right side of the heart and lessen compression on the LV ("pancake" effect), thus improving LV function. The disadvantages of RV plication or resection include potential compromise of the coronary arterial supply to the RV and potential development of ventricular arrhythmias. Although partial RV resection was performed in only 3 patients in this series, we now have a lower threshold to apply it to large areas of thinned atrialized inferior RV. The resection is performed as an ellipse from base to apex, which brings the acute margin of the RV in close proximity to the posterior descending coronary artery. This results in a suture line that is parallel to branches of the right coronary artery, thus minimizing coronary compromise. When plication or resection is performed, antiarrhythmic therapy (usually amiodarone) is used for approximately 3 months postoperatively.
Pharmacologic management at the time of separation from cardiopulmonary bypass includes routine use of epinephrine and milrinone infusions. Lidocaine or amiodarone therapy is used if there are any atrial or ventricular tachyarrhythmias present. Adjuncts to operation that we have also applied to this group of patients include a low threshold for delayed sternal closure. Maneuvers to decrease RV afterload, (ie, decrease PAP) have included mild hyperventilation, the selective use of nitric oxide, and intra-aortic balloon counterpulsation, especially in adults with concomitant depression of LV function.
Treatment of patients with Ebstein anomaly is the most challenging in those who have biventricular dysfunction. Three patients in this series had depressed LVEF (35% in 2 and 40% in 1). The function and geometry of the LV can be altered by dilated right-sided chambers.19 Quantification of ventricular function can be difficult if the LV is underfilled and compressed by a dilated RV; associated paradoxical motion of the septum also makes it difficult to estimate the LVEF. After surgical repair, the postoperative LV function improved in each of these patients. This may be related to better diastolic filling after the volume load on the RV was reduced and/or an increase in LV preload provided by the BCPS.
The preoperative evaluation of a patient with depressed LV function may include a hemodynamic cardiac catheterization to obtain pulmonary arterial and left-sided filling pressures to ascertain that hemodynamics will be appropriate for the construction of a BCPS. Coronary angiography may be done at the same time. Heart transplantation is reserved for those patients who have significant LV dysfunction (LVEF < 25%). Patients who have moderate depression (LVEF > 40%) can usually undergo a conventional operation (with or without a BCPS). The surgical management of patients with an LVEF between 25% and 35% is the most difficult and is evolving, as we now are more likely to consider the use of the BCPS. If hemodynamic catheterization confirms the ability to perform a BCPS, we then proceed with a conventional operation that may include a BCPS. Intraoperative direct pressure measurements are performed before a BCPS is considered. This shunt is permissible in the setting of depressed LV function provided the LV end-diastolic pressure is less than 15 mm Hg, the transpulmonary gradient is less than 10 mm Hg, and the mean PAP is less than 18 to 20 mm Hg.
Three patients in this series were initially referred for cardiac transplantation. All were adults who had heart failure with depressed LV function. One patient, who had an LVEF of 35%, had his medication regimen adjusted and his ventricular response to atrial fibrillation controlled. His LVEF improved to 55% before the operation. This demonstrates the importance of an aggressive medical heart failure regimen, which includes rhythm and rate control of atrial tachyarrhythmias, to optimize ventricular function. In patients with a history of atrial tachyarrythmias, it also underscores the importance of performing a maze procedure at the time of operation to restore or maintain sinus rhythm postoperatively.3 The other 2 patients had LVEFs of 35% and 40%. The favorable outcome of these 3 patients after a conventional operation with a BCPS implies that well-selected patients may benefit from this approach. In addition, it appears that functional capacity improves in the short term, but longer follow-up is required to know whether improvements of LV function and functional capacity are maintained. It is not known whether the BCPS will only bridge these patients to heart transplantation.11
Another adjunct that can be applied to the surgical treatment of patients with Ebstein anomaly and a failing RV is the placement of an atrial septal fenestration or subtotal closure of an atrial septal defect. This may be done in neonatal patients whose elevated pulmonary resistance is a contraindication to a BCPS. However, in older patients, it has been our experience that profound arterial desaturation from severe right-to-left shunting may occur in this setting. Consequently, we now close all atrial septal defects completely and use the BCPS as our main adjunct in this group of patients.
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Study Limitations |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionStudy LimitationsConclusionsReferences |
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The ability to systematically and accurately report RV size and function by echocardiography can be difficult,20 especially in patients with Ebstein anomaly. The RV fractional area change may underestimate the degree of RV dysfunction when severe TV regurgitation is present. LV function can also be difficult to quantitate. We now obtain magnetic resonance imaging studies to better quantitate the size and function of the atrialized and functional RV, especially in those patients with RV dysfunction.
This observational, nonrandomized study is limited to our experience with patients with Ebstein anomaly who had a BCPS constructed as part of their surgical treatment. Many of these patients underwent the creation of a BCPS in anticipation of RV failure, and others had the shunt constructed as a salvage procedure owing to hemodynamic instability. In the operations in which the shunt was planned, we can only assume, but cannot prove, that the operative mortality was reduced by using the BCPS. Further experience is needed to identify which patients should undergo BCPS as part of their repair. A randomized trial would be difficult to implement and power.
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Conclusions |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionStudy LimitationsConclusionsReferences |
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionStudy LimitationsConclusionsReferences |
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