Operations for subaortic stenosis in univentricular hearts

The choice of palliative arterial switch operation as an alternative for selected cases in a single center: Experience and mid term results

INTRODUCTION AND OBJECTIVE

There are various management options for newborns with single ventricle physiology, ventriculoarterial discordance and subaortic stenosis, classically involving the early pulmonary banding and aortic arch repair, the restricted bulboventriculer foramen enlargement or the Norwood and the Damus-Kaye-Stansel procedures. The aim of this study is to evaluate our preferred technique and comment on the midterm results of our clinical experience with palliative arterial switch operation (pASO) for a certain subset of patients.

METHOD

We hereby retrospectively evaluate the charts of patients who went through pASO, as initial palliation through Fontan pathway, starting from 2014 till today.

RESULTS

Ten patients underwent an initial palliative arterial switch procedure. Eight of 10 patients survived the operation and discharged. Seven of 10 patients completed Stage II and 1 patient reached the Fontan completion stage and the other six of ten (6/10) patients are doing well and waiting for the next stage of palliation. There are two mortalities in the series (2/10) and one patient lost to follow-up (1/10).

CONCLUSION

In our opinion, the pASO can be considered as an alternative palliation option for patients with single ventricle physiology, transposition of the great arteries and systemic outflow tract obstruction despite longer cross clamp times compared to other methods, but It not only preserves systolic and diastolic ventricular function, but also provides a superior anatomic arrangement for following stages.

Physiological Fontan Procedure

Objective: The conventional Fontan circulation deviates the superior vena cava (SVC = 1/3 of the systemic venous return) toward the right lung (3/5 of total lung volume) and the inferior vena cava (IVC = 2/3 of the systemic venous return) toward the left lung (2/5 of total lung volume). A "physiological" Fontan deviating the SVC toward the left lung and the IVC toward the right lung was compared with the conventional setting by computational fluid dynamics, studying whether this setting achieves a more favorable hemodynamics than the conventional Fontan circulation. Materials and Methods: An in-silico 3D parametric model of the Fontan procedure was developed using idealized vascular geometries with invariant sizes of SVC, IVC, right pulmonary artery (RPA), and left pulmonary artery (LPA), steady inflow velocities at IVC and SVC, and constant equal outflow pressures at RPA and LPA. These parameters were set to perform finite-volume incompressible steady flow simulations, assuming a single-phase, Newtonian, isothermal, laminar blood flow. Numerically converged finite-volume mass and momentum flow balances determined the inlet pressures and the outflow rates. Numerical closed-path integration of energy fluxes across domain boundaries determined the flow energy loss rate through the Fontan circulation. The comparison evaluated: (1) mean IVC pressure; (2) energy loss rate; (3) kinetic energy maximum value throughout the domain volume. Results: The comparison of the physiological vs. conventional Fontan provided these results: (1) mean IVC pressure 13.9 vs. 14.1 mmHg (= 0.2 mmHg reduction); (2) energy loss rate 5.55 vs. 6.61 mW (= 16% reduction); (3) maximum kinetic energy 283 vs. 396 J/m3 (= 29% reduction). Conclusions: A more physiological flow distribution is accompanied by a reduction of mean IVC pressure and by substantial reductions of energy loss rate and of peak kinetic energy. The potential clinical impact of these hemodynamic changes in reducing the incidence and severity of the adverse long-term effects of the Fontan circulation, in particular liver failure and protein-losing enteropathy, still remains to be assessed and will be the subject of future work.

Long-Term Outcome of Direct Relief of Subaortic Stenosis in Single Ventricle Patients

Background:

Single ventricle patients with unrestrictive pulmonary blood flow and (potential) subaortic stenosis are challenging to manage and optimal surgical strategy is unknown. Direct relief of subaortic stenosis by enlargement of the ventricular septal defect and/or subaortic chamber has generally been replaced by a Damus-Kaye-Stansel or Norwood procedure due to concerns of iatrogenic heart block, reobstruction, or ventricular dysfunction. Studies reporting long-term outcome after the direct approach are limited. The aim of our study was to describe and analyze our experience with direct relief of subaortic stenosis in single ventricle patients.

Methods:

Demographic data, characteristics, and pre-operative, operative and outcome details were collected for children undergoing direct relief of subaortic stenosis between 1989 and 2016.

Results:

Twenty-three patients (median age: 7.4 months, range: 10 days to 5.5 years) underwent direct relief of subaortic stenosis. Complete follow-up was available for all patients (median: 15.6 years, range: 34 days to 26.3 years). Seven (30%) patients had recurrence of subaortic stenosis. One (4%) patient developed complete heart block and one patient developed moderate ventricular dysfunction. Five (50%) patients developed a (pseudo)aneurysm at site of the patch and ventriculotomy. There were two perioperative deaths. Eighty-six percent of patients underwent a successful Fontan procedure.

Conclusions:

Direct relief of subaortic stenosis is associated with a substantial risk of reobstruction and patch (pseudo)aneurysm formation. However, risk of heart block is low and long-term outcome is good with the majority of patients reaching Fontan completion. In our opinion, the direct approach appears to be a good and relatively simple procedure in selected cases for the treatment of subaortic stenosis.

Palliative arterial switch as first-line treatment before the fontan procedure in patients with single-ventricle physiology and subaortic stenosis

INTRODUCTION AND OBJECTIVES

There are several techniques for the palliative treatment of patients with single-ventricle physiology, ventriculoarterial discordance and subaortic stenosis. The Fontan procedure relies on optimal initial palliation to avoid the development of subaortic stenosis (as well as ventricular hypertrophy and diastolic dysfunction).

METHODS

We present seven patients with single-ventricle physiology, transposition of the great arteries and subaortic stenosis, with low systemic output and high pulmonary flow, aged 21 to 383 days (median, 75) and weighing between 3.4 and 9.6kg (median, 4.2). All were treated with a palliative arterial switch, thus "switching" their subaortic stenosis to subpulmonary stenosis. Six patients also underwent aortic arch surgery, 4 an atrial septectomy, and 1 a subaortic membrane resection.

RESULTS

One patient died after surgery, another developed recoarctation, which was treated with an angioplasty, 3 patients reached the Glenn stage and 2 the Fontan stage. All had good ventricular function.

CONCLUSIONS

A palliative switch is an effective initial treatment for single-ventricle physiology with transposition of the great arteries and subaortic stenosis. This complex initial technique produces good results and allows the patient to progress to the Glenn or Fontan stage.

Outcomes of patients born with single-ventricle physiology and aortic arch obstruction: the 26-year Melbourne experience

BACKGROUND

To review the long-term outcomes of patients born with single-ventricle physiology and aortic arch obstruction.

METHODS

Follow-up of 70 consecutive neonates undergoing single-ventricle palliation and arch repair, excluding hypoplastic left heart syndrome, between 1983 and 2008, was reviewed. Dominant arch anomalies were coarctation (n = 48), interrupted arch (n = 10), and hypoplastic arch alone (n = 12). Neonatal Damus procedure with arch repair and shunt became the dominant approach, being performed in 1 (10%) of 10 in 1983 to 1989, 9 (32%) of 28 in 1990 to 1999, and 23 (72%) of 32 in 2000 to 2008.

RESULTS

All patients underwent an initial procedure at a median of 6 days (range, 4-12 days): pulmonary artery banding and arch repair (n = 35); Damus, arch repair, and shunt (n = 33); and other (n = 2). Twenty-six patients died before Fontan completion. Of the 34 survivors of initial banding, 17 (50%) later required a Damus and 4 (12%) required subaortic stenosis relief. Forty patients underwent Fontan completion at a median age of 5 years (range, 4-7 years). After a mean of 5 ± 6 years after Fontan, there was 1 hospital death and 1 Fontan takedown. Overall survival was similar if patients initially underwent a Damus or pulmonary artery banding (P = .3). Overall survival at 10 years was 53% (95% confidence interval, 42%-67%).

CONCLUSIONS

Patients born with single-ventricle physiology and arch obstruction have a high risk of mortality in the first years of life. Their outcomes seem excellent once they reach Fontan status. It is likely that, in patients with single-ventricle and arch obstruction, strategies to avoid systemic outflow tract obstruction should be implemented in early life, and regular monitoring of blood pressure is warranted.

Management of the single ventricle and potentially obstructive systemic ventricular outflow tract

Multi-stage palliation is the current management strategy for the treatment of children with various single ventricle (SV) cardiac malformations. The success of this strategy depends on the presence of favorable anatomic and hemodynamic criteria. Several SV anomalies have the potential of developing systemic ventricular outflow tract obstruction (SVOTO) that might be evident early on or progress later after palliative surgeries. SVOTO could result in ventricular hypertrophy, impaired diastolic function and subendocardial ischemia with subsequent deleterious effects on the SV and disturbance of some of those criteria for a successful multi-stage palliation strategy. Careful identification of SV patients at risk of developing SVOTO and proper planning of the optimal palliation sequence beginning at the 1st stage procedure are vital factors that would affect long-term outcomes in those patients. In the current review, we describe the morphology of SV patients with potential SVOTO risk, surgical procedures that address potential or present SVOTO, and optimal timing of those procedures within the multi-stage palliation chain. We attempt to provide a treatment algorithm for various patients taking into consideration their unique anatomic and physiologic characteristics.

Palliative arterial switch operation in the context of multiple ventricular septal defects, potentially biventricular and univentricular hearts with malposed great arteries: a review of 15 cases

BACKGROUND

This study is an examination of our unit's experience with palliative arterial switch in univentricular and potentially biventricular hearts with transposition of the great arteries (TGA).

METHODS

These patients were divided into three groups based on their physiology. (a) Single ventricle physiology (n = 8), in which all the patients had univentricular hearts, TGA, and subaortic stenosis (SAS). (b) Borderline biventricular physiology (n = 4), in which the patients had TGA, ventricular septal defect (VSD), and hypoplastic right ventricle (RV). (c) Biventricular physiology (n = 3), in which the patients had TGA and multiple VSDs.

RESULTS

In all, 12 (80%) patients survived. Seven of these have undergone second stage surgery (cavopulmonary shunt, n = 5; biventricular repair, n = 2).

CONCLUSION

Palliative arterial switch is an alternative to Norwood procedure and modifications thereof for managing SAS in single ventricle with malposed great arteries. Palliative switch with adjunctive pulmonary artery band may be a temporizing measure in TGA with multiple VSDs, where the VSDs are judged to be inaccessible through the tricuspid valve or through either of the great arteries. It may also be utilized for TGA and hypoplastic RV instead of committing them to univentricular pathway and keeping the option of biventricular repair.

Management of older single functioning ventricles with outlet obstruction due to a restricted "VSD" in double inlet left ventricle and in complex double outlet right ventricle

The occurrence of a restriction of the bulbo-ventricular foramen (BVF) in older patient with double inlet left ventricle (DILV) or tricuspid atresia (TA) with ventriculo-arterial discordance is a well-known condition. Today, the surgical management is to perform a Damus-type operation at the time of the bi-directional Glenn or at the Fontan completion. The ventricular septal defect (VSD) enlargement, associated with muscular resection and a patch enlargement of the subaortic accessory ventricular chamber, is rarely performed but remains indicated in cases with pulmonary valve atresia or regurgitation. This condition is essentially prevented by doing an early Norwood-type operation in the presence of DILV/TA with transposition of the great arteries associated with an aortic arch obstruction. The palliative switch operation is an option that was abandoned because of poor control of the pulmonary blood flow. It is only in cases of large unobstructed BVF that pulmonary artery banding could be undertaken in neonates, followed by close echocardiographic follow-up. The occurrence of a restriction or a closure of the VSD in complex DORV following a Fontan operation is a dramatic event and is quite "new business." It has been recently recognized that the VSD becomes restricted in a number of patients with DORV-nc-VSD treated with a Fontan palliation. This new condition is not surprising knowing that 75% of the VSDs must be enlarged preventively in DORV-nc-VSD repair. In the setting of a Fontan circulation, the supra-systemic left ventricle has severe consequences the right ventricle performance. Attempts at surgical VSD enlargement or catheter-based procedures have resulted in almost constant recurrence. This recently reported complication is in favor of also performing a VSD enlargement at the time of the Fontan completion in complex DORV. It justifies the biventricular repair in complex DORV with two viable ventricles.

Pulmonary artery banding before the Damus-Kaye-Stansel procedure

Subaortic stenosis (SAS) in a single ventricle leads to myocardial hypertrophy and compromises Fontan results. Moreover, controversy exists concerning the optimal surgical strategy for relieving SAS. We have applied pulmonary artery banding (PAB) before the Damus-Kaye-Stansel procedure (DKS), and here we analyze factors that influence systemic ventricular compliance. Thirteen patients underwent PAB before DKS. Median PAB duration was 5.5 months (range, 20 days to 17.7 months). Procedures administered concomitantly with DKS were Blalock-Taussig shunt (n = 6), bidirectional cavopulmonary shunt (n = 5), and Fontan operation (n = 2). All survived and were doing well after a median follow-up 2.7 years. Cardiac catheterization before DKS showed that the mean pressure gradient across the systemic ventricular outflow tract and PAB were 20.6 +/- 10.1 and 67.4 +/- 10.2 mmHg, respectively. After DKS, systemic ventricular end diastolic pressure (SVEDP) was significantly correlated with PAB duration (r = 0.65, p = 0.022), but not with PAB or systemic ventricle outflow tract pressure gradients. After DKS, SVEDP decreased or fell to within the range in patients with PAB duration less than 7 months (p < 0.05). Seven patients had a successful Fontan operation, and 6 without risk factors are waiting operation. SVEDP was found to be correlated with PAB duration, and our findings indicate that short-term PAB can be considered a safe option in patients with a single ventricle and SAS.

Late complications associated with the Fontan circulation

The recent significant reduction in operative mortality associated with surgical completion of the Fontan circulation is clearly multi-factorial. Better understanding of the fundamental physiological and anatomical issues have led to refinements in operative technique, early neutralization of potential risk factors, widespread use of a staged approach, and selective application of the concept of fenestration or incomplete partitioning. While further reduction of operative mortality is important, and may be anticipated in the future, major emphasis now must be placed on optimizing functional outcome, and understanding and managing the late complications associated with the unique physiology produced by the Fontan circulation.

Designing therapeutic strategies for patients with a dominant left ventricle, discordant ventriculo-arterial connections, and unobstructed flow of blood to the lungs

The palliation of the cyanotic child with a dominant morphologically left ventricle, discordant ventriculo-arterial connections, and obstruction to the pulmonary outflow tract has continued to evolve and mature. The evolution began in the early days of surgical palliation with the Blalock-Taussig shunt, extended to construction of cavopulmonary shunts, if required, and then to the Fontan procedure and its subsequent modifications. This journey took nearly 30 years to complete. There is increasing clinical data to document the beneficial effects of this approach, with ever-improving outcomes. Some aspects of the history of the cavopulmonary shunt have been previously reviewed in this journal and elsewhere, as have analysis of outcomes for some groups of patients considered for surgical completion of the Fontan circulation. While there has been some ongoing interest in ventricular septation since the early success of Sakakibara et al., this approach has largely been abandoned. Considerably more challenges and debate resonate in the surgical algorithms defined for patients whose hearts are characterized by a dominant left ventricle, discordant ventriculo-arterial connections, and unobstructed flow of blood to the lungs. This latter group will be the focus of this review, as will the aetiology of the myocardial hypertrophy that is particularly frequent in this group of patients, its clinical recognition, indeed its anticipation, and the multiple surgical strategies designed to prevent or treat it. All these manoeuvres are considered to optimise suitability for, and outcome from, creation of the Fontan circulation.

Outcomes of tricuspid atresia in the Fontan era

BACKGROUND

Whereas indications expand and results improve with increasing refinements to the Fontan procedure the overall impact on outcomes related to tricuspid atresia remains suboptimally defined.

METHODS

We reviewed 225 consecutive patients presenting between 1971 and 1999. All patients had classic tricuspid atresia with absent right atrioventricular connection and with D-transposition of the great arteries in 21%, pulmonary outflow obstruction in 75%, and aortic outflow obstruction in 11%.

RESULTS

Ten patients died before any intervention and 3 patients were lost to follow-up. Palliative procedures (includes 151 with systemic shunt, 27 pulmonary artery banding, 60 venous shunt) were performed in 203 patients, with 44 deaths, 8 patients awaiting Fontan, 12 patients Fontan contraindicated, and 11 patients lost-to-follow-up. A total of 137 patients had the Fontan procedure (9 patients without previous procedures) with 7 early deaths, 11 late deaths, and 3 patients progressing to heart transplantation. Total survival for the cohort was 90% at the age of 1 month, 81% at 1 year, 70% at 10 years, and 60% at 20 years with no significant change over the time period. Independent factors associated with ineligibility or death without Fontan (n = 68, 30%) included earlier birth date, lower birth weight, presence of aortic arch anomaly and greater right ventricular hypoplasia, and no palliative procedure. There were no significant changes in mortality with Fontan over the study time period with survival of 95% at 1 month, 93% at 1year, and 82% at 10 years.

CONCLUSIONS

Improvements in outcomes with tricuspid atresia will require attention to management and risk factors before Fontan.

Management of univentricular heart with systemic ventricular outflow obstruction by pulmonary artery banding and Damus-Kaye-Stansel operation

BACKGROUND

Some patients with univentricular hearts who are candidates for Fontan operation may develop ventricular outflow tract obstruction after pulmonary artery banding (PAB) or Fontan. However, the indication for Damus-Kaye-Stansel (DKS) operation for these patients has not been clear. To clarify the indication, the changes in the diameter of ventricular outflow tract and the feasibility of DKS operation before or with Fontan were investigated.

METHODS

Among the patients with univentricular heart who underwent PAB, 21 patients had probable ventricular outflow obstruction with an aorta arising from the morphologic right ventricle. Diameter of ventricular outflow tract was measured before and after PAB, Glenn, and Fontan operations with or without DKS, and indexed by normal value (%VOT).

RESULTS

Six patients died after PAB. In the surviving 15 patients, %VOT decreased significantly from 103% (median, range 75%-153%) to 75% (range 52%-153%) after PAB. Four with very small %VOT (52% to 63%) after PAB needed DKS with bidirectional Glenn or central shunt operation, and 5 with moderately small %VOT (67% to 109%) after PAB needed DKS concomitantly with Fontan. A patient with %VOT of 117% before Fontan required DKS after Fontan. A patient with %VOT of 153% underwent Fontan without DKS and obstruction did not develop after Fontan. The remaining 4 patients were under consideration for Glenn or Fontan operation.

CONCLUSIONS

The diameter of the ventricular outflow tract decreased after PAB and Fontan operations. DKS operations might be indicated before Fontan if the indexed diameter of ventricular outflow tract after PAB was below 70% and concomitantly with Fontan if it was below 120%.

Single ventricle with systemic obstruction in early life: comparison of initial pulmonary artery banding versus the Norwood operation

OBJECTIVES

The outcomes of initial pulmonary artery banding (PAB)+/-coarctation repair are compared with the Norwood operation in newborns with single ventricle (SV) and systemic obstruction (SO).

METHODS

Between January 1987 and July 2000, 22 patients (median age, 12 days) with SV and aortic arch obstruction (AAO), subaortic stenosis (SAS), or both underwent surgery. Two initial surgical approaches were used: PAB+/-coarctation repair (group I, seven patients); Norwood type operation (group II, 15 patients).

RESULTS

The overall mortality was 32% (seven of 22 patients). There was no late mortality. The mortality in group I was 43% versus 27% in group II. Recently, there has been no mortality following the Norwood operation in the last eight patients operated since 1995. Of the survivors, nine patients have undergone the Fontan operation and four patients have had the bidirectional Glenn (BDG) with no deaths. There was one repair of supravalvar aortic stenosis at the time of BDG in group II as opposed to eight reinterventions for SAS and/or AAO in four patients in group I (P=0.01).

CONCLUSIONS

PAB+/-coarctation repair for SV and SO is associated with a high mortality and a high reoperation rate for SAS or recurrent AAO. Although the Norwood operation was also associated with a high mortality early on, it can now be performed with excellent outcome. This improvement, combined with a low reintervention rate for SAS or AAO, suggests that the Norwood operation is likely to emerge as the procedure of choice for SV and SO.

Long-term results of relief of subaortic stenosis in univentricular atrioventricular connection with discordant ventriculoarterial connections

BACKGROUND

We set out to examine the long-term results of relief of subaortic stenosis by enlargement of ventricular septal defect in patients with univentricular atrioventricular connection to a dominant left ventricle and discordant ventriculoarterial connections.

METHODS

Twenty-four patients underwent enlargement of ventricular septal defect between 1985 and 1998 at a median age of 3.2 years (range, 3 weeks to 14 years). Ten patients were younger than 1 year of age. Eighteen had undergone previous banding of the pulmonary trunk, 9 of whom also required repair of coarctation of the aorta. The median subaortic gradient before enlargement was 46 mm Hg. Twenty-three patients had a patch to enlarge the rudimentary right ventricle.

RESULTS

Five patients (21%) died in the early postoperative period. The overall survival at 1 and 3 years was 73%, and at 5 and 10 years was 68% and 60%, respectively. Complete heart block requiring insertion of a pacemaker occurred in 2 patients (8%). A Fontan operation was performed in 10 patients, 5 underwent a bidirectional Glenn procedure, and 2 required cardiac transplantation. Follow-up was complete in all survivors at a median time of 6.7 years (range, 8 months to 13 years). From the earlier part of the series, 3 patients experienced aortic insufficiency and 2 had recurrent obstruction. Factors adversely affecting survival were age younger than 1 year at operation and presence of obstruction within the aortic arch.

CONCLUSIONS

Our experience shows that, in patients with univentricular atrioventricular connection to a dominant left ventricle and subaortic stenosis, enlargement of the ventricular septal defect provides satisfactory relief of obstruction except in those younger than 1 year of age, and those who have associated obstruction in the aortic arch.

Neonatal cardiac surgery. Anatomic, physiologic, and technical considerations

Neonatal repair for all cardiac lesions is an attractive but as yet unattainable goal for the surgical team. We are obliged to consider both lesions that must be repaired in the absolute neonatal period, and those for which later repair is an option. This article serves as an update on some issues relating to neonatal heart surgery. The first section deals with selected general aspects of perioperative support. The second section discusses two representative lesions that illustrate many of the problems encountered in neonatal cardiac surgery: transposition of the great arteries and hypoplastic left heart syndrome.

Transthoracic 3-dimensional echocardiography in the assessment of subaortic stenosis due to a restrictive ventricular septal defect in double inlet left ventricle with discordant ventriculoarterial connections

To evaluate the accuracy and clinical utility of three-dimensional echocardiography in the assessment of the size and shape of the ventricular septal defect in double inlet left ventricle.

METHODS

We validated the technique in an autopsy study, and then performed a clinical investigation. Six autopsied hearts were immersed in a waterbath and examined with 3-dimensional echocardiography. We identified the cross-section within the dataset which optimally displayed the ventricular septal defect "en face", and compared its smallest and largest diameters, as well as its area. The ventricular septal defect was then filled with a silicone sealant and a section prepared for direct measurement. In patients, we measured the diameters and area of the ventricular septal defect in endsystole nad computed the aortic valvar area in endsystole from the cross-section showing the aortic valve "en face". Ten patients with double inlet left ventricle, aged between 2 and 15 years, were studied using rotational or parallel scanning. All patients had undergone banding of the pulmonary trunk at a mean age of 7 (3-36) days, usually at the time of repair of the coarctation. Two patients had undergone surgical enlargement of the ventricular septal defect prior to echocardiographic examination.

RESULTS

The correlation between the areas of the ventricular septal defect in the specimens measured directly and by 3-dimensional echocardiography was r=0.98, with limits of agreement between -0.1-0.08 cm2. In the patients, the area of the defect was measured as 3.9+/-2 cm2, whereas the aortic valvar area was 2.6+/-0.9 cm2. The ratio between the areas was 1.5 (0.5-2.3). Three patients with areas of the ventricular septal defect smaller than those of the aortic valve had resting Doppler gradients between double inlet left ventricle and the aorta of 16, 20 and 30 mm Hgs, respectively.

CONCLUSIONS

3-dimensional echocardiography provides accurate assessment of the area of the ventricular septal defect in double inlet left ventricle, and is helpful in identifying patients with subaortic stenosis caused by restrictive defects.

Staged surgical approach to neonates with aortic obstruction and single-ventricle physiology

BACKGROUND

The surgical management of neonatal systemic outflow obstruction and complex single ventricle pathology is variable.

METHODS

In 15 neonates (12 boys and 3 girls) with complex forms of single-ventricle pathology and aortic coarctation or interruption, an initial strategy of banding the pulmonary artery and repair of the obstruction from a left thoracotomy was undertaken.

RESULTS

The median age at operation was 6 days (range 2 to 33 days) and the median weight was 3.3 kg (range 2 to 4.6 kg). There were no early deaths and one late death after the initial surgical palliation. Of the 14 survivors, 8 have undergone a bidirectional cavopulmonary anastomosis. The median age for bidirectional Glenn was 9.75 months (range 3.5 to 26 months). Seven infants have required Damus-Kaye-Stansel reconstruction for subaortic obstruction (one early death). The median age of the Damus-Kaye-Stansel procedure was 4 months (range 3 weeks to 9 months). Thirteen of 15 patients (87%) are alive and 6 have proceeded to a Fontan operation (median follow-up 68 months). A single failing Fontan required takedown to bidirectional Glenn and central shunt.

CONCLUSIONS

Our experience suggests that this high-risk subgroup of neonates with aortic obstruction and single-ventricle pathophysiology is safely managed by initial pulmonary artery banding palliation and repair of aortic obstruction. This strategy, careful surveillance, and early relief of subaortic stenosis can maintain acceptable anatomy and hemodynamics for later bidirectional Glenn and Fontan procedures.

Subaortic obstruction and the Fontan operation

Systemic outflow tract obstruction in the heart with a functional single ventricle promotes myocardial hypertrophy, and this has been shown to be an unequivocal risk factor for poor outcome at Fontan procedure. Such systemic outflow tract obstruction may be congenital or acquired. Those factors contributing to acquired systemic outflow tract obstruction in those patients with a double-inlet left ventricle, a rudimentary right ventricle, and a discordant ventriculoarterial connection include the size of the ventricular septal defect, previous pulmonary artery banding, and other volume unloading surgical procedures. Staging with a bidirectional cavopulmonary connection and construction of a proximal pulmonary artery-aortic connection or ventricular septal defect enlargement has neutralized this factor.

Modified Damus-Kaye-Stansel procedure for single ventricle, subaortic stenosis, and arch obstruction in neonates and infants: midterm results and techniques for avoiding circulatory arrest

BACKGROUND

A modified Damus-Kaye-Stansel procedure is one of several options for palliation of single ventricle with subaortic obstruction, but results in neonates have been disappointing. In the presence of arch obstruction, this procedure is typically performed with circulatory arrest, which may contribute to neurologic insult.

METHODS

Since 1990, a modified Damus-Kaye-Stansel procedure has been performed in 14 neonates and seven infants with single ventricle and subaortic stenosis, including 15 with arch obstruction. Diagnoses were double-inlet left ventricle (n = 12), tricuspid atresia (n = 2), and other forms of hypoplastic ventricle with subaortic obstruction (n = 7). Three patients underwent concurrent bidirectional Glenn shunt. In the most recent seven patients with arch obstruction, arch repair was achieved with an end-to-side anastomosis of the descending aorta to the ascending aorta with continuous upper body perfusion.

RESULTS

One early death occurred among the 14 neonates (7%) and three among the infants, for an early mortality of 19%. At a median follow-up of 33 months, there were no late deaths or neurologic complications. Nine patients underwent subsequent bidirectional Glenn anastomosis, including three who had Fontan completion and one who later underwent conversion to a partial biventricular repair. One patient required a transplant for cardiomyopathy of unknown etiology. The remaining 12 patients are considered good candidates for Fontan completion. No patient has recurrent arch obstruction. Four patients have mild (n = 1) or trivial (n = 3) semilunar valvular regurgitation.

CONCLUSION

The modified Damus-Kaye-Stansel procedure is an effective primary palliation for single ventricle and subaortic stenosis, with or without arch obstruction. Results are especially encouraging in neonates. Arch repair can be achieved without circulatory arrest to the brain.

Instantaneous Subaortic Obstruction after Closure of Aortopulmonary Shunt

We report the case of a young child with tricuspid atresia, discordant ventriculoarterial connection, rudimentary right ventricle, and mildly restrictive bulboventricular foramen. Intraoperative temporary snaring of the modified Blalock-Taussig shunt resulted in a dramatic volume reduction of the left ventricle, a decrease in bulboventricular foramen size, and an instantaneous increase in the gradient across the latter from 15 mm Hg before occlusion of the shunt to 44 mm Hg. A modified Damus-Stancel-Kaye procedure resulted in early relief of the aortic outflow obstruction; in addition, a bidirectional cavopulmonary anastomosis was constructed. The use of intraoperative echocardiography is recommended to monitor subaortic obstruction in procedures that unload volume in univentricular hearts with discordant ventriculoarterial connection.

Allograft root on closed pulmonary valve for subaortic obstruction in double-inlet left ventricle with transposition of the great arteries

BACKGROUND

Until recently closure of the pulmonary valve during staged Fontan-type palliation in the setting of double-inlet left ventricle with an unrestrictive or adequately enlarged ventricular septal defect and transposition of the great arteries with the aorta on a left-sided outflow chamber was regarded as an appropriate part of surgical treatment. Lately, however, an increased incidence of subsequent subaortic obstruction has been described in this regard.

METHODS

Allograft root placement on the previously closed pulmonary orifice in combination with a modified Damus-Kaye-Stansel procedure is described to create an unobstructed outflow from the main ventricle to the systemic circulation. This procedure was done in 3 patients. One root placement was combined with the construction of the bidirectional superior cavopulmonary connection, one was done as an intermediate step before completion of the cavopulmonary connection, and one was combined with completion of total cavopulmonary connection.

RESULTS

Immediate relief of the subaortic obstruction was achieved in all 3 patients. Ventricular hypertrophy, echocardiographically assessed by diastolic posterior wall thickness, regressed to normal in all 3 within 6 to 12 months.

CONCLUSIONS

Allograft root placement on the reopened pulmonary orifice in double-inlet left ventricle with a ventricular septal defect and transposition of the great arteries appears technically feasible and functionally adequate on short-term follow-up. This procedure should result in regression of ventricular hypertrophy to allow eligibility for a Fontan-type palliation again. To what extent possible failure of the allograft increases the risk of an adverse outcome of this palliation may be a matter of concern.

Avoidance of subaortic obstruction in staged management of single ventricle

BACKGROUND

Subaortic obstruction is a frequent accompaniment of single-ventricle anatomy. Most often, the aorta arises from an outflow chamber that is connected to the single ventricle by a bulboventricular foramen or ventricular septal defect. This connection may be restrictive of flow at birth, or may become obstructive after surgical procedures that reduce the volume work of the ventricle. Subaortic obstruction is recognized as a risk factor for reconstructive surgical procedures for single ventricle.

METHODS

To prevent the consequences of subaortic obstruction, we have routinely amalgamated the proximal main pulmonary artery with the ascending aorta and arch early in the management of these patients. From September 1990 through September 1994, 29 neonates and infants with single ventricle and established or potential subaortic obstruction underwent staged reconstructive surgical procedures. The initial operation in the newborn period was a Norwood procedure (18 patients) or a pulmonary artery band (5 patients). All survivors underwent a hemi-Fontan procedure at approximately 6 months.

RESULTS

Eighteen patients have undergone a completion Fontan operation with no deaths. Five await completion Fontan. None has subaortic obstruction, and none has pulmonary valve insufficiency that is graded more than mild.

CONCLUSIONS

Early association of the proximal main pulmonary artery with the ascending aorta appears to obviate the risks and complications associated with subaortic obstruction in patients with single ventricle.

Systemic obstruction in univentricular hearts: surgical options for neonates

BACKGROUND

The surgical management for bridging patients with univentricular heart and systemic obstruction to a Fontan procedure remains controversial.

METHODS

Twenty-seven of 96 patients with univentricular heart and unobstructed pulmonary blood flow referred for surgical palliation were seen with systemic obstruction. Twenty-six were neonates with coarctation of the aorta in 21 and subaortic stenosis in 5. In 8 other patients, subaortic stenosis developed after initial pulmonary artery banding. Four different palliative procedures were performed: coarctation repair with pulmonary artery banding (group I, n = 15); Norwood or Damus-Kaye-Stansel or arterial switch operation (group II, n = 9); coarctation repair with pulmonary artery banding and bulboventricular foramen enlargement (group III, n = 2); and orthotopic heart transplantation with coarctation repair (group IV, n = 1).

RESULTS

The mortality rate was 34.3% (n = 12) for all patients, 53.3% in group I, 33.3% in group II (p = 0.003 versus group I), and 50% in group III. Nine patients (8 in group I and 1 in group II) had development of subaortic stenosis and underwent a subsequent procedure: Damus-Kaye-Stansel operation in 5, arterial switch operation in 3, and bulboventricular foramen enlargement in 1. Three had a concomitant or subsequent Fontan procedure and 2, a bidirectional Glenn procedure. In group II, 1 patient underwent a subsequent Fontan procedure and another, a bidirectional Glenn anastomosis. Six of the 8 patients with subaortic stenosis after initial pulmonary artery banding underwent a second stage consisting of a Damus-Kaye-Stansel procedure (n = 3), bulboventricular foramen enlargement (n = 2), or creation of an aortopulmonary window (n = 1). Three had a concomitant Fontan procedure and 2, a bidirectional Glenn procedure. Actuarial 4-year survival was 65.5% +/- 8.4% (70% confidence limits) for all patients; it was 40% +/- 13.3% in group I and 66.6% +/- 16.3% in group II (p < 0.05).

CONCLUSIONS

Initial management of patients with univentricular heart and systemic obstruction by Norwood-like procedures provides a better outcome. Success of the Fontan operation relies on the ability to provide timely relief of subaortic stenosis.

Modified surgical techniques for relief of aortic obstruction in [S,L,L] hearts with rudimentary right ventricle and restrictive bulboventricular foramen

Modified techniques of aortopulmonary anastomosis were performed in six neonates with atrioventricular and ventriculoarterial discordance [S,L,L], double-inlet left ventricle, and restrictive bulboventricular foramen area (mean index 1.10 cm2/m2) with unobstructed aortic arch (n = 3) or with hypoplasia (n = 2) or interruption (n = 1) of the aortic arch. In cases of unobstructed aortic arch, a flap of autogenous aortic tissue was used to augment the posterior aspect of the anastomosis of the main pulmonary artery to the ascending aorta, thus creating the potential for anastomotic growth; this technique is applicable regardless of the position of the ascending aorta relative to the main pulmonary artery. In case of levo-transposition of the aorta with hypoplasia or interruption of the aortic arch, a modified Norwood procedure was performed, in that the proximal ascending aorta was divided at the same level as the main pulmonary artery with subsequent homograft patch augmentation from the main pulmonary artery-ascending aorta anastomosis to the level of the proximal descending aorta; this technique avoids a spiraling incision of the aorta and therefore reduces the risk of torsion of the aortic root with its inherent risks of obstruction of the coronary circulation and aortic or pulmonary valve regurgitation. There was no early or late mortality. At a mean follow-up of 16 months, in all patients, there was unobstructed aortic outflow, as evidenced by echocardiographic absence of a significant ventricular-aortic systolic gradient (mean 4.5 +/- 4 mm Hg) and absence of distal aortic arch obstruction. There was no evidence of aortic or pulmonary valve regurgitation. The reported modified techniques provide effective relief of restrictive bulboventricular foramen and aortic obstruction in [S,L,L] hearts.

Experimental ablation of outflow tract muscle with a thermal balloon catheter

BACKGROUND

Pulmonary balloon valvuloplasty has been performed in selected patients with tetralogy of Fallot as an alternative to surgical palliation; this technique is limited, however, by the fact that the balloon has little effect on the dynamic, muscular contribution to outflow tract obstruction. In an experimental model, we used a new thermal balloon catheter to ablate right ventricular outflow tract muscle. We evaluated the acute efficacy and muscle ablation parameters of this technology and its effects after myocardial healing.

METHODS AND RESULTS

A prototype electrolyte-filled balloon catheter, heated by radiofrequency energy, was constructed. Studies were conducted to determine the optimum electrolyte solution needed to minimize balloon heating time with an unmodified, commercially available radiofrequency generator. In vivo ablations of right ventricular outflow tract muscle with the thermal balloon were performed in lambs that were divided into three groups (n = 5 each) according to the duration of thermal energy delivery (20, 40, and 60 seconds, respectively). Ablated lesion volume increased (460 +/- 63 to 1156 +/- 256 mm3) as the energy delivery time increased (20 to 60 seconds) and was correlated with delivered energy, temperature integral, and maximum epicardial surface temperature (r = .85, .82, and .72, respectively). All five lesions in the 60-second group showed an acute decrease of the wall thickness. Additional in vivo ablations were performed in 6 animals in which survival studies showed muscle thinning, healing by fibrosis, and no evidence of aneurysm formation.

CONCLUSIONS

Thermal energy can be used with a balloon catheter delivery system to ablate myocardium. This study suggests that this energy delivery technology might be useful for relief of muscular outflow tract obstruction and that further studies are warranted.

Successful application of the Norwood procedure for infants without hypoplastic left heart syndrome

Although the first-stage Norwood procedure mostly has been used for hypoplastic left heart syndrome, there are other anomalies in which the Norwood procedure can be applied. Since 1991, 18 newborns without hypoplastic left heart syndrome underwent a first-stage Norwood procedure. All had a hypoplastic aortic annulus, ascending aorta, and transverse aorta. Ten had normally related great arteries: aortic atresia or aortic stenosis with inadequate left ventricle in 4, mitral atresia or stenosis in 4, and interrupted aortic arch in 2. The 8 others had double-outlet right ventricle with mitral atresia or complete transposition with a hypoplastic right ventricle. Age ranged from 2 to 77 days (median, 6 days) and weight from 2.4 to 4.4 kg (mean, 3.0 kg). The patients with interrupted aortic arch simultaneously underwent primary repair of the interruption. There were 17 hospital survivors (94%). There have been no late deaths in follow-up from 4 to 30 months (mean, 15.5 months). Thirteen children have had subsequent creation of a bidirectional Glenn shunt with takedown of the original systemic to pulmonary shunt. The 2 with interrupted aortic arch underwent a Rastelli-type biventricular repair. These results show that the Norwood procedure can be applied to infants without hypoplastic left heart syndrome who have hypoplastic aortas and excessive pulmonary blood flow with very low mortality and excellent palliation.

Damus-Kaye-Stansel procedure: midterm follow-up and technical considerations

The Damus-Kaye-Stansel operation is useful in the management of complex congenital heart defects. We reviewed our experience with 23 patients who underwent a Damus-Kaye-Stansel procedure. The anastomotic technique was individualized depending on the anatomy. The aortic and pulmonary artery incisions were carried into the sinuses of Valsalva in 9 patients, the aorta was transected in 11 patients, and a patch was used to augment the anastomosis in 13 patients. Concurrent procedures included a Fontan operation (n = 9, mortality = 0), right ventricle-pulmonary artery conduit (n = 5, mortality = 0), bidirectional Glenn procedure (n = 6, mortality = 1), and central aortopulmonary shunt (n = 3, mortality = 2; emergency = 1). Survival is 87% with a median follow-up of 7 years (range, 2 months to 9.2 years). Four patients underwent late revision of the Damus-Kaye-Stansel connection. All survivors are asymptomatic. We conclude that the Damus-Kaye-Stansel connection provides excellent midterm results when the proximal anastomosis is adapted to the anatomy of the patient.

Tricuspid atresia presenting in infancy. Survival and suitability for the Fontan operation

BACKGROUND

The Fontan operation is the usual goal of therapy for children with tricuspid atresia. The influences of morphology and different management strategies on survival and subsequent suitability for this procedure are crucial but unstudied in an unselected population during the Fontan era.

METHODS AND RESULTS

The fates of 237 consecutive infants with tricuspid atresia were reviewed (1972-1987; median follow-up, 8.0 years). Overall actuarial survival was 72% at 1 year, 53% at 5 years, and 46% at 10 years. Univariate risk factor analysis established that discordant ventriculoarterial connections (24% of the group; relative risk, 2.7), pulmonary atresia (14%, 2.3), aortic arch obstruction (7%, 2.9), and subaortic stenosis (8%, 4.2) were associated with poor survival, whereas pulmonary stenosis (60%, 0.52), balanced pulmonary blood flow (9%, 0.25), and older age at presentation (33%, 0.42) were beneficial. Multivariate analysis allowed the creation of predictive patient-specific survival curves and two additive indexes. Survival was worse for patients who underwent banding of the pulmonary trunk with aortic arch repair than for other individual palliative procedures (p < 0.001). On retrospective review, 204 patients (86%) were judged suitable for a future Fontan procedure at presentation. However, 99 (48%) of these are known to have died before a Fontan operation or became unsuitable for such surgery during follow-up, mostly because of death after palliative surgery (23 patients, 11%), sudden death (18 patients, 9%), and new adverse features (32 patients, 16%) such as subaortic stenosis, pulmonary arterial distortion, and ventricular dysfunction.

CONCLUSIONS

Management in infancy must aim to ensure survival and maintain suitability for a Fontan-type operation. The accumulating incidence of adverse events with increasing age would argue in favor of undertaking definitive surgery in early childhood in most patients.

Recent results with the modified Fontan operation

From Jan 1989 to December 1991, 61 patients had modified Fontan procedures for a variety of lesions, including tricuspid atresia (18), mitral atresia (3), double inlet ventricle (14), isomeric hearts (4) and others (22). The hospital mortality was 1.6% (70% CL.0.2-5.3%). There were 2 late deaths. The median age at operation was 3.7 years (mean 5.6, range 1.5 to 20.3 years). There were two late failures at 2 months and 30 months after the operation, requiring take down of the Fontan in one and heart transplantation in the other. The 89% of the patients followed up are in NYHA class I or II at a mean follow up of 21.5 months (range 3-35 months). This suggests that the modified Fontan operation performed with the current patient selection criteria can be performed with a low mortality and that the early results are encouraging in the majority of the patients.