The pericardial membrane pulmonary monocusp: surgical technique and early results

An in vitro study of the influence of monocusp patch size on the hemodynamics for reconstructing right ventricular outflow tract in tetralogy of Fallot

For relief of right ventricular outflow tract obstruction in the operative treatment of tetralogy of Fallot and other complex congenital heart disease, it is often necessary to perform transannular monocusp patch to prevent right ventricular pressure overload and reduce pulmonary regurgitation. But the the geometric relationship between a monocusp patch length and the size of RVOT is not well defined. Five 20 mm sized monocusp patches were tested in simulated RVOTs which sized from 18 mm to 22 mm at 1 mm interval, respectively. The hydrodynamics of the patches were assessed through a quasi-physiological artery pulsatile flow duplicator system. The transvalvular pressure difference, effective orifice area and regurgitation flow were determined. The results showed that the regurgitation fraction increased with the diameter of RVOT increased (from 6.25% at 18 mm RVOT to 26.63% at 22 mm RVOT). Implant an oversized monocusp patch in RVOT reconstruction can effectively decrease the regurgitation but increase the transvalvular pressure and may reduce the longevity of leaflet.

Fate of Polytetrafluoroethylene Monocusp Pulmonary Valves in an Animal Model

Creation of a competent pulmonary monocusp valve facilitates transition from pressure to volume overload following right ventricular outflow tract reconstruction. To determine intermediate-term results and performance of the different types of polytetrafluoroethylene membrane used to construct monocusp valves and transannular patches, 12 infant lambs underwent excision of the native pulmonary valve and insertion of a monocusp valve and transannular patch made from one of 4 types of membrane. Echocardiography was performed after 3, 6, 9, and 12 months, and cardiac catheterization was carried out prior to animal sacrifice at 6 ( n = 4) or 12 ( n = 8) months. There was no postoperative morbidity or mortality. On echocardiography, 6 valves were mobile (50%), 4 had diminished mobility (33%), and 2 were fixed (17%) prior to sacrifice. At catheterization, mild, moderate, and severe pulmonary regurgitation was observed in 4 valves each (33%), with no stenosis. Right ventricular outflow tract reconstruction with polytetrafluoroethylene monocusp valves can be safely accomplished with good early competence, variable degrees of late insufficiency, and no stenosis. Compared to an open microstructure, the closed polytetrafluoroethylene microstructure showed a milder fibroinflammatory reaction and fewer foci of microcalcification, with sparing of the free edge of the monocusp; this correlated with better intermediate-term hemodynamic performance.

Right ventricular outflow tract strategies for repair of tetralogy of Fallot: effect of monocusp valve reconstruction

OBJECTIVES

The absence of a pulmonary valve (PV) after tetralogy of Fallot (TOF) repair has been shown to impact postoperative right ventricular (RV) function. The purposes of this study were to (i) compare early outcomes after PV-sparing vs transannular patching (TAP) with monocusp valve reconstruction or TAP alone and (b) assess the mid-term results after polytetrafluoroethylene (PTFE) membrane monocusp reconstruction.

METHODS

From 2003 to 2009, 163 patients underwent TOF repair. Sixty-nine patients (42.3%) underwent a PV-sparing procedure (Group A), 74 (45.4%) underwent PTFE membrane monocusp valve reconstruction (Group B) and 20 (12.3%) underwent TAP only (Group C). Early outcomes were evaluated by the right-to-left ventricular pressure ratio, RV outflow tract gradient, tricuspid and PV function, intensive care unit (ICU) parameters and need for reintervention. Group B patients were also evaluated at intermediate term for clinical and echocardiographic parameters, including tricuspid and monocusp valve function and mobility.

RESULTS

The median age, weight and PV Z-value of Group B patients were significantly lower; 20.5 months, 9.3 kg and -4, respectively. Postoperatively, the right-to-left ventricular pressure ratio was <0.5 in all groups. Mechanical ventilation time, fluid drainage duration and total ICU stay showed no significant difference between Groups A and B, while Group C was significantly longer (P < 0.01). There were five (3%) early deaths: three from Group A and two from Group B. The incidences of moderate or severe pulmonary insufficiency (PI) on discharge were 8.2% in Group A, 9% in Group B and 50% in Group C (P < 0.001). Among Group B patients, 85% of the evaluated patients had less than moderate PI in the intermediate-term follow-up, QRS duration <140 ms in 83.3% and right-to-left ventricular diameter ratio of 0.6 ± 0.2. Two (2.6%) patients underwent reoperation for monocusp replacement. There were two (2.7%) mid-term deaths.

CONCLUSIONS

The use of a PTFE membrane monocusp valve and a valve-sparing strategy prevents immediate PI and improves short-term clinical outcomes. PTFE membrane monocusp appears advantageous in preventing severe intermediate-term PI and facilitates the preservation of RV function.

Tetralogy of fallot: a surgical perspective

Tetralogy of Fallot (TOF) is an index lesion for all paediatric and congenital heart surgeons. In designing an appropriate operation for children with TOF, the predicted postoperative physiology must be taken into account, both for the short and long term. A favourable balance between pulmonary stenosis (PS) and pulmonary insufficiency (PI) may be critical for preservation of biventricular function. A unified repair strategy to limit both residual PS and PI is presented, along with supportive experimental evidence. A strategy for dealing with coronary anomalies and some comments regarding best timing of operation are also included.

Tetralogy of Fallot: Current surgical perspective

Tetralogy of Fallot (TOF) is an important lesion for all pediatric and congenital heart surgeons. In designing the most appropriate operation for children with TOF, the postoperative physiology should be taken into account, both in the short and long term. The balance between pulmonary stenosis (PS) and pulmonary insufficiency (PI) may be critical for preservation of ventricular function. A unified repair strategy that limits both residual PS and PI is presented, along with supporting experimental evidence, a strategy for dealing with coronary anomalies, and comments regarding best timing of operation.

Use of a pulmonary neovalve with a transannular patch for repair of tetralogy of fallot

INTRODUCTION AND OBJECTIVES

To report on our initial experience with the implantation of a pulmonary valve using Nunn's technique in association with a transannular patch for the complete repair of the tetralogy of Fallot.

METHODS

In total, 21 patients were treated between September 2008 and February 2010. Their ages ranged from 7 months to 15 years (median 12 months) and weights from 6.8 kg to 44 kg (median 10 kg). Four patients had previously undergone palliative shunt placement; in two, it was associated with the diagnosis of a complete atrioventricular septal defect. Use of the transannular patch (treated autologous pericardium) was preceded by implantation of a 0.1-mm polytetrafluoroethylene (PTFE) monocusp valve using posterior fixation. Intraoperative transesophageal echocardiography and pressure gradient measurement were carried out, and echocardiography was repeated before discharge.

RESULTS

No deaths were recorded. One patient had a residual ventricular septal defect that required reintervention. Echocardiography showed that the maximum gradient across the PTFE valve was 25 mmHg. Regurgitation was mild in 19 cases and moderate in 2 (the first and second in the series).

CONCLUSIONS

Initial results using a transannular patch with a modified monocusp valve to repair the outflow tract in the tetralogy of Fallot were promising: there was only a slight pressure gradient and mild regurgitation. A medium-or long-term follow-up study is required to confirm these findings and to compare them with results obtained using other techniques.

The current strategy of repair of tetralogy of Fallot in children and adults

OBJECTIVES

The strategies of repair of tetralogy of Fallot change with the age of patients. In children older than 4 years and adults, the optimal strategy may be to use different method of reconstruction of the right ventricular outflow tract from those followed in younger children, so as to avoid, or reduce, the pulmonary insufficiency that is increasingly known to compromise right ventricular function.

METHODS

From April, 2001, through May, 2008, we undertook complete repair in 312 patients, 180 male and 132 female, with a mean age of 11.3 years +/-0.4 years, and a range from 4 to 48 years, with typical clinical and morphological features of tetralogy of Fallot, including 42 patients with the ventriculo-arterial connection of double outlet right ventricle. The operation was performed under moderate hypothermia using blood cardioplegia. The ventricular septal defect was closed with a Dacron patch. When it was considered necessary to resect the musculature within the right ventricular outflow tract, or perform pulmonary valvotomy, we sought to preserve the function of the pulmonary valve by protecting as far as possible the native leaflets, or creating a folded monocusp of autologous pericardium.

RESULTS

The repair was achieved completely through right atrium in 192, through the right ventricular outflow tract in 83, and through the right atrium, the outflow tract, and the pulmonary trunk in 36 patients. A transjunctional patch was inserted in 169 patients, non-valved in all but 9. There were no differences regarding the periods of aortic cross-clamping or cardiopulmonary bypass. Of the patients, 5 died (1.6%), with no influence noted for the transjunctional patch. Of those having a non-valved patch inserted, three-tenths had pulmonary regurgitation of various degree, while those having a valved patch had minimal pulmonary insufficiency and good right ventricular function postoperatively, this being maintained after follow-up of 8 to 24-months.

CONCLUSIONS

Based on our experience, we suggest that the current strategy of repair of tetralogy of Fallot in older children and adults should be based on minimizing the insertion of transjunctional patches, this being indicated only in those with very small ventriculo-pulmonary junctions. If such a patch is necessary, then steps should be taken to preserve the function of the pulmonary valve.

Durability of hand-sewn valves in the right ventricular outlet

OBJECTIVE

The objective was to compare the medium- and long-term outcomes for pericardial monocusp valves, polytetrafluoroethylene (Gore-Tex, WL Gore and Associates Inc, Flagstaff, Ariz) 0.1-mm monocusp valves, and bileaflet 0.l-mm polytetrafluoroethylene valves and their efficiency in the right ventricular outlet.

METHODS

We reviewed all hand-sewn right ventricular outlet valves created by the author (Graham R. Nunn) in the setting of repaired tetralogy of Fallot or equivalent right ventricular outlet pathology when the native pulmonary valve could not be preserved. The valves were assessed by serial transthoracic echocardiography and more recently by magnetic resonance imaging angiography for late valve function. The bileaflet polytetrafluoroethylene valves were constructed in a standardized fashion from a semicircle of 0.1-mm polytetrafluoroethylene (the radius of which equaled the length of the outflow tract incision) that gave a lengthened free edge to the leaflets, central fixation of the free edge posteriorly just proximal to the branch pulmonary arteries, and generous augmentation of the outflow tract with polytetrafluoroethylene patch-plasty. The bileaflet configuration shortens the closing time against the posterior wall, and the leaflets are forced to maintain their configuration without prolapse into the right ventricular outlet. The valve can be generously oversized in young children to try to avoid the need for replacement.

RESULTS

A total of 54 patients met the selection criteria--22 patients received fresh autologous pericardial monocusps, 7 patients received polytetrafluoroethylene (0.1-mm) monocusps, and 25 patients received bileaflet polytetrafluoroethylene (0.1-mm) outlet valves. The pericardial valves have the longest follow-up, and all valves developed free pulmonary incompetence. Polytetrafluoroethylene monocusps had reliable competence early after surgery but progressed to pulmonary incompetence. The bileaflet polytetrafluoroethylene (0.1-mm) valves have remained competent with regurgitant fractions of only 5% to 30% (magnetic resonance imaging angiography), and this has remained stable with time. The maximum follow-up for these valves is 5 years. No stenosis or peripheral emboli have been recognized, and no valves have been replaced to date.

CONCLUSION

Hand-sewn bileaflet polytetrafluoroethylene valves in the right ventricular outlet can reliably provide competence and maintain function in the medium term. Their shape and size allow placement in young children with a reasonable expectation that they will remain competent with growth of the native annulus and not require replacement. Their durability is superior to the pericardial and polytetrafluoroethylene monocusp valves in this series.

Factors related to the durability of a homograft monocusp valve inserted during repair of tetralogy of Fallot as based on the mid- to long-term outcomes

OBJECTIVES

To maintain pulmonary valvar function subsequent to repair of tetralogy of Fallot, we have inserted a homograft monocusp when a transjunctional patch was required. In this study, we have evaluated the mid- to long-term outcomes, aiming to determine the durability of the homograft.

METHODS

Among 218 repairs performed for tetralogy of Fallot between July, 1996, and June, 2005, we inserted homograft monocusps in 54 patients, 4 of whom had associated absent pulmonary valve syndrome, 3 had pulmonary valvar atresia, and 1 had an atrioventricular septal defect with common atrioventricular junction. The median body weight at surgery was 7.8 kilograms, with a range from 3.9 to 42 kilograms. The function of the monocusp valve was assessed by regular echocardiography, using the Kaplan-Meier method and the Cox regression model for statistical analyses.

RESULTS

There were 2 early deaths (3.7%), associated with respiratory infection. No late deaths were observed during the follow-up, which ranged from 0.3 to 120 months, with a median of 64.3 months. Freedom from valvar dysfunction was 67.2 +/- 6.7% at 1 year, 37.1 +/- 7.3% at 3 years, 23.8 +/- 6.7% at 5 years, and 21.2 +/- 6.4% at 7 years. We needed to replace the valve in 1 patient during follow-up. We found that ABO blood group incompatibility, stenosis of the pulmonary arteries, and associated absent pulmonary valve syndrome all adversely affected the function of the monocusp.

CONCLUSION

Our experiences show that insertion of a homograft monocusp can prevent pulmonary regurgitation in the early period after repair of tetralogy of Fallot, but the effects are limited in duration as degeneration progressed. We still need to determine whether this finding can improve the longer-term function of the right ventricle.

A New Technique of Transannular Monocusp Patch-Repair of the Right Ventricular Outflow Tract in Repair of Tetralogy of Fallot

Reconstruction of the right ventricular outflow tract (RVOT) is a key procedure in repair of Tetralogy of Fallot (TOF). The procedure creates pulmonary insufficiency (PI) that may compromise the right ventricular (RV) function, particularly during late follow-up. A simple way to reduce PI is to create a monocusp patch from xenografts, homografts, fascia lata, and autologous pulmonary artery or pericardium. Each of those has limitations. The autologous pericardial valve sewn on another pericardial patch is one of the earliest monocusp patches used clinically but loses anti-PI effect soon after the operation presumably due to degeneration or absorption of the monocusp. I have therefore designed and used a new technique (folded monocusp patch) to create a monocusp for TOF repair in children and adults. The technique has been used in nine patients of the 18 TOF patients who needed transannular patch-repair in total 74 TOF repairs. The monocusp patch-repaired patients had minimal or mild PI and good RV function beyond 8-12 months. The long-term results await follow-up and further study in multi-institutions.

Pulmonary valve cusp augmentation with autologous pericardium may improve early outcome for tetralogy of Fallot

OBJECTIVES

The transannular patch used to relieve right ventricular outflow tract obstruction in children with tetralogy of Fallot may result in pulmonary insufficiency. We hypothesized that pulmonary valve cusp augmentation with pericardium would decrease pulmonary insufficiency and improve the early outcome for transatrial-transpulmonary tetralogy of Fallot repair requiring transannular patch.

METHODS

Since November 2001, 41 patients with tetralogy of Fallot and 2 patients with isolated pulmonary valve stenosis had relief of right ventricular outflow tract obstruction with either a transannular patch plus pulmonary valve cusp augmentation (n = 18) or a transannular patch alone (n = 25). Data were retrospectively collected.

RESULTS

The median age (5.3 vs 3.2 months; P = .09) and weight (6.4 vs 5.2 kg; P = .3) were similar for the cusp augmentation and transannular patch groups, respectively. The diameter of the pulmonary valve annulus (6.4 vs 6.0 mm; P = .57) and the McGoon index (1.47 vs 1.69, P = .75) were also similar. The mean aortic clamp time (48 +/- 18 minutes vs 52 +/- 19 minutes; P = .46) and median cardiopulmonary bypass time (89 vs 91 minutes; P = .9) did not differ. One patient with a transannular patch died of multiorgan system failure. Patients with a pulmonary valve cusp augmentation had a shorter duration of intubation (1 vs 3 days; P < .001) and intensive care unit stay (2 vs 8 days; P < .001). Thirteen patients with a transannular patch and 1 patient with a pulmonary valve cusp augmentation required inotropic support for more than 72 hours (P = .001). Discharge echocardiograms demonstrated moderate or severe pulmonary insufficiency in 5 patients with a pulmonary valve cusp augmentation and in 21 patients with a transannular patch (P < .001). At 7.5 months, 3 patients (17%) with a pulmonary valve cusp augmentation had progression of pulmonary insufficiency.

CONCLUSIONS

Augmentation of a pulmonary valve cusp reduces the incidence of clinically significant postoperative pulmonary insufficiency. This technique may improve the early outcome for children with tetralogy of Fallot requiring a transannular patch.

Nonsurgical pulmonary valve replacement: Why, when, and how?

Percutaneous transcatheter interventions for valve replacement or implantation is one of the most exciting developments in the field of interventional cardiology. Valvular stenosis has been treated by balloon dilatation with early and late results; however, treatment for valvular regurgitation has remained surgical until now. Most new designs have been investigated for implantation of valves in the left or right ventricular outflow tracts. Patients with surgery on the right ventricular outflow tract for congenital heart disease constitute the most common group for reoperations during late follow-up. Surgical pulmonary valve replacement can be performed with low mortality; however, it sets up a substrate for future operations. Also, the risk of cardiopulmonary bypass, infection, bleeding, and ventricular dysfunction remains. A transcatheter technique is likely to have more acceptance and may expand the indications for early intervention for right ventricular outflow tract dysfunction.

Annular and leaflet augmentation in Noonan's syndrome with dysplastic pulmonary valve

Two patients with dysplastic pulmonary valves associated with Noonan's syndrome successfully underwent leaflet augmentation with pericardial membrane and annular enlargement with preservation of valve competence. Both patients are doing well at 36 and 37 months, respectively, postoperatively. Echocardiography and clinical assessment showed gradients of 12 and 16 mmHg, respectively, and negligible pulmonary valve insufficiency. The surgical technique is simple and provides an attractive alternative in patients with dysplastic pulmonary valve and small pulmonary orifice and annulus.

Modified Lecompte procedure for the anomalies of ventriculoarterial connection

BACKGROUND

The Lecompte procedure for correcting transposition of the great arteries has an advantage because it obviates the need for an extracardiac conduit for the reconstruction of the pulmonary outflow tract. In this study, we evaluated the effectiveness and the application of the Lecompte procedure based on our experiences.

METHODS

A retrospective review was conducted of the records of 45 patients who underwent the Lecompte procedure during the past 11 years to achieve direct right ventricle to pulmonary artery continuity. Mean age at operation was 2.4+/-1.7 years (range 3.5 months to 6.9 years). The diagnoses involved anomalies of the ventriculoarterial connection with ventricular septal defect and pulmonary outflow tract obstruction, such as transposition of the great arteries, double-outlet right ventricle, and double-outlet left ventricle.

RESULTS

Early mortality was 4.4% (2 of 45 patients) and late mortality was 4.7% (2 of 43). The mean follow-up was 4.9+/-3.1 years. Fourteen patients (34.1% of survivors, n = 41) had pulmonary stenosis (pressure gradient above 30 mm Hg), the main reason for which was a calcified monocusp valve (n = 10, 71.4%). Eight of 45 patients (17.8%) underwent reoperation: 2 for residual ventricular septal defect, 1 for recurrent septic vegetation, and 5 for pulmonary stenosis. The cumulative survival rates were 91.1%+/-4.2% at 10 years. The actuarial probabilities of freedom from reoperation for pulmonary stenosis were 93.8%+/-4.3% and 71.4%+/-11.8% at 5 and 10 years, respectively.

CONCLUSIONS

Our review suggests that the Lecompte procedure is an effective treatment modality for anomalies of the ventriculoarterial connection with ventricular septal defect and pulmonary outflow tract obstruction. Repair in early age is possible with acceptable morbidity and mortality, but recurrent right ventricular outflow tract obstruction caused by degeneration of the monocusp valve is a problem that needs resolution.