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When replacement of the aortic valve in neonates and infants is required, the Ross-Konno procedure provides a high-quality left ventricular outflow with good mid-term durability. The procedural outcome is highly dependent on the pre-procedural condition of the neonate or infant. Most series contain substantial numbers of post-balloon valvotomy patients as emergent or urgent management of severe, acute regurgitation. In patients with compromised ventricular function, post-operative mechanical support may be required but is generally associated with a good outcome. The neonatal and infant autograft may perform better in the long term than un-supported autografts performed later in life. Early definitive or delayed treatment of left ventricular outflow tract pathology associated with aortic interruption increasingly involves an infant Ross-Konno. The procedure also has a role in the recruitment of small left ventricles. Concomitant mitral pathology or aortic obstruction magnifies complexity, but the operative approach to the Ross-Konno remains the same.
When replacement of the aortic valve in neonates and infants is required, the Ross-Konno procedure provides a high-quality left ventricular outflow with good mid-term durability.
Introduction
This paper describes the technique of the Ross procedure in neonates and infants, typically for managing aortic stenosis with a hypoplastic aortic annulus. Many lessons from adolescent and adult application of this technique may be applied to pediatric practice. The long-term advantages of aortic valve replacement with a pulmonary autograft vs other forms of replacement are clear and have been demonstrated in many patients and several countries.
Dorobantu DM, Taliotis D, Tulloh RM, et al. Surgical versus balloon valvotomy in neonates and infants: results from the UK National Audit. Open Hear. 2019;6:e000938. https://doi.org/10.1136/openhrt-2018-000938
a subset of very abnormal and dysplastic valves will not achieve a sustained relief of obstruction with either approach. These valves often have more severe annular hypoplasia and are more likely to leak after the initial intervention. In such annuli, dense fibrous tissue, often extending to the sub-valvar area, limits potential growth. When the decision is made to replace the valve, resection of this material with a small incision to break the annular ring is sometimes all that is required to provide a satisfactory left ventricular outflow and accommodate a pulmonary autograft. Although this short incision is described as a “Konno,” it is rare to need a long septal incision and patching of the resulting “VSD.” In this way, the “Konno” component is far more limited when compared to the Konno aortoventriculoplasty required when placing a mechanical valve in an older child or when augmenting the left ventricular outflow septum to address left ventricular outflow tract obstruction in the context of atrioventricular septal defect, where the aortic valve is a normal size.
Infant and neonatal Ross-Konno procedures are not dramatically different from adult Ross procedures, except for the patient's frailty. In the neonate, the procedure is often performed only when deferral of aortic valve surgery is not possible, and a definitive operation is the only pathway to salvage the patient. So, these patients often come to surgery with ventricular dysfunction and co-existing pathology, including mitral stenosis and aortic arch obstruction. This likely accounts for the high rate of mortality
Key modifications of techniques developed in Ross procedures in larger patients for neonatal and infant application include the use of a continuous suture for the inflow suture line, use of the muscle skirt on the autograft to augment the area of the Konno incision,
The procedure is performed through a standard midline sternotomy incision. The thymus is sub totally resected. A vertical pericardiotomy is performed. The ascending aorta and main pulmonary artery are separated. The aortic and pulmonary roots are dissected down to the area of fusion of the conotruncus, the fibrous tissue between the 2 roots. The branch pulmonary arteries are mobilized to their first branches. Systemic heparin is administered. Purse-strings are placed in the distal ascending aorta near the origin of the innominate artery and the superior and inferior caval veins. A left ventricular vent is placed through a purse-string at the right superior pulmonary vein and left atrial junction and passed across the mitral valve into the left ventricle. Cardiopulmonary bypass is initiated, with cooling to 28°C. A left ventricular vent is placed through a purse-string at the right superior pulmonary vein and left atrial junction and passed across the mitral valve into the left ventricle. An antegrade cardioplegia cannula is placed in the ascending aorta. The aorta is cross-clamped, and cardioplegia is delivered. If there is severe aortic valve regurgitation, the left ventricular vent may be placed immediately before going onto bypass, with readiness for aortic cross-clamping, the opening of the aorta, and direct delivery of cardioplegia into the coronary ostia.
If present, the ductus is ligated with a 5/0 polypropylene secured to the ductal adventitia. The distal main pulmonary artery is divided distally at the pulmonary confluence to allow inspection of the pulmonary valve. A trileaflet pulmonary valve with thin and mobile leaflets is confirmed suitable for use.
An aortotomy is completed to transect the ascending aorta above the sinotubular junction. Care is taken to identify the coronary artery ostia before completion of this incision. The course of each coronary artery can be confirmed by gently sounding with a malleable coronary probe.
The coronary artery ostia are excised with generous rims of aortic tissue, often the complete sinus, to maximize the size of the coronary buttons. Traction sutures are placed on the apices of the aortic valve commissural posts.
The aortic valve morphology is inspected. The aortic valve cusps are excised. The proximal coronary arteries are mobilized from the epicardium. Although the coronary arteries will be placed orthotopically, the size difference between native and neo-aortic roots means some redundancy helps optimize coronary artery position.
The pulmonary autograft is then removed. A right-angle clamp is passed through the pulmonary valve to a point approximately 1 cm below the nadir of the pulmonary valve cusp. This location is confirmed with direct inspection through the pulmonary valve. The right ventricular free wall indentation is then incised with a scalpel.
The right ventricular free wall incision is then extended on the anterior surface laterally and medially with scissors. Care is taken to avoid injury to the nadir of the pulmonary valve cusps as the incision is extended leftward towards to left anterior descending artery and rightward towards the septum.
Figure 8-The autograft is removed from the right ventricular outflow tract by separating it from the posterior ventricle. In most cases, a plane may be developed between the muscular tube of the pulmonary root and the septum beneath. Coronary artery branches from the left anterior descending (LAD) coronary artery may be seen in or on the septum, immediately below the dissection plane. The largest of these, the septal perforating branch, originates behind the medial-posterior commissure of the pulmonary valve. It then courses into the infundibular septum towards the anterior papillary muscle of the tricuspid valve. Avoiding injury to important coronary branches can largely be achieved by maintaining the correct plane. The muscle of Lancisi is another important landmark in this area.
Figure 8Excision of the pulmonary valve - posterior right ventricular outflow.
The size of the pulmonary autograft is then measured using marked dilators to guide the selection of an appropriate right-ventricle-to-pulmonary-artery conduit. The optimal conduit for most 3 kg neonates is a 12 mm pulmonary homograft.
The Konno incision is then made. The tissue between aortic and pulmonary outflows is inspected. The incision is initiated to the right of the right-left commissure and the left of the right coronary artery incision. The incision then continues into the interventricular septum for a short distance, overcoming the annular hypoplasia. Sometimes division and resection of fibrous tissue beneath the annulus are required. The extent of the incision depends on the degree of enlargement of the left ventricular outflow tract that is necessary and is guided by an assessment of the autograft size made earlier. A large incision is rarely needed.
Antegrade cardioplegia is re-dosed by direct infusion. Cardioplegia administration also identifies bleeding sites on the proximal right ventricular outflow tract where the autograft was excised. These bleeding sites can be addressed with simple polypropylene sutures and electrocautery.
The proximal autograft is secured to the left ventricular outflow tract. The autograft commissures are marked with a sterile marker on the outside of the autograft. The autograft is positioned so that the posterior sinus aligns with the left coronary sinus, and the natural curve of the pulmonary autograft emulates the native aorta. The commissures are then marked with three 5-0 polypropylene sutures. These sutures assist in spreading the autograft evenly. Even in patients with dysplastic unicuspid valves, three commissural pillars are often visible and are used as marking points. Figure 13A demonstrates that these sutures are then run continuously to the adjacent commissure suture and tied, thus securing the autograft to the left ventricular outflow tract. A second layer of continuous 6-0 polypropylene is then run as a ‘whip-stitch’ around the inflow suture line, mainly to enhance hemostasis.
Figure 13Securing the autograft to the enlarged aortic annulus using three running sutures.
Figure 14Use of a bovine pericardial strip to reinforce the suture line connecting the area of Konno enlargement to the autograft, and provide a possible landing zone for the proximal RVOT reconstruction.
In some situations, reinforcement of the initial inflow suture is useful, and a strip of bovine pericardium can be used for this purpose; to bolster the suture line and to also provide a landing zone for the proximal reconstruction of the right ventricular outflow tract (Fig. 18). In patients where a larger Konno incision is required, a “VSD” patch may be helpful to prevent excessive anterior tilting of the autograft that may impact the distal (outflow) suture line. This is rarely required in neonates, and care should be taken in securing the patch to the right side of the septum as this is a frequent site of postoperative bleeding.
Figure 18Reconstruction of the right ventricular outflow tract with pulmonary autograft.
Left coronary artery reimplantation. A small defect is created in the left sinus of Valsalva with an 11-blade. A 4.0mm hole punch (Quest Medical Inc., Allen, TX) is then utilized to develop a precise circular defect in the autograft sinus. Care is taken to ensure the leaflet is adequately retracted from the sinus wall before incision.
The left coronary artery button is then re-implanted into the autograft with a continuous 7-0 polypropylene suture. Following the anastomosis, the coronary is probed with a malleable coronary probe.
The right coronary is similarly re-implanted into the autograft to the left coronary artery button with a continuous 7-0 polypropylene suture. Some surgeons prefer to complete the distal anastomosis and fill the root by briefly removing the cross-clamp, to better understand the ideal position for the right coronary button. The right ventricular outflow tract reconstruction begins with the anastomosis between the branch pulmonary arteries and right-ventricle-to-pulmonary-conduit. The homograft is thawed and trimmed proximal to the branch pulmonary artery bifurcation. The distal autograft is then anastomosed to the native ascending aorta. The anterior surface of the native ascending aorta can be incised vertically to address any size disparity between the native ascending aorta and the autograft. Both distal anastomoses are typically completed with a continuous 6-0 or 7-0 polypropylene suture.
Patient re-warming begins as the proximal connection of the right ventricular outflow tract anastomosis begins. If bovine pericardium is used to buttress the area of Konno enlargement, then the edge of the bovine pericardium can be used to secure the homograft in this area. The anterior part of the connection to the free wall of the right ventricle can usually be sutured directly without additional tissue. The proximal anastomosis is completed with a 5-0 or 6-0 polypropylene suture. Care should be taken suturing the homograft to the left lateral aspect of the autograft harvest site. The left anterior descending coronary artery is often very close at this point. In addition, and where possible, sutures should incorporate the epicardium (for structural integrity) and the cut face of the muscle (for hemostasis). Liberal use of pledget-supported sutures for reinforcement in this area before cross-clamp removal can help prevent bleeding in this location.
The heart is deaired through the aortic root vent, and the aortic cross-clamp is removed. The left ventricular vent is maintained during cardiac recovery from myocardial ischemia to avoid distention. The patient is weaned and separated from cardiopulmonary bypass in the usual way. In marginal situations, a left atrial line inserted via the left atrial appendage provides valuable information about optimal filling. Modified ultrafiltration is carried out before reversal of the heparin and decannulation. This operation has a high risk of bleeding, and proactive administration of coagulation products, including prothrombin complex concentrate, helps quickly address coagulopathic bleeding. Temporary atrial and ventricular pacing leads are placed. A transesophageal or epicardial echocardiogram should be used to assess ventricular function, confirm flow in the proximal coronary arteries, and assess mitral regurgitation and conduit function. Imperfect implantation of the right coronary can cause ventricular dysfunction and should be considered if the hemodynamics are poor.
Closing Comments
The Ross-Konno operation is an infrequent but essential component of neonatal and infant cardiac surgery. It is rarely performed in “ideal” candidates. Concomitant aortic arch obstruction and mitral valve pathology are frequently associated with severe stenosis of the left ventricular outflow and annulus.
Historically, neonatal and infant Ross-Konno has been avoided because of the high perioperative mortality associated with the procedure, reported in registry data (∼ 18% rising to 33% in those requiring concomitant aortic arch repair
In appropriate patients, the superiority of the autograft valve over alternatives, including repaired aortic valves, has an important benefit in the growing child with a wide and straight left ventricular outflow.
The Ross-Konno in neonates and infants is subject to the usual criticisms of the procedure at any age; that it creates “2-valve” disease, that the autograft function may not be preserved over time, and that neo-aortic root dilatation will ultimately require difficult reinterventions. Notwithstanding these valid concerns, it is the best solution we have for the maintenance of left ventricular function, at least in the mid-term, in this age group.
Based on institutional experience with neonatal and infant aortic valve repair, strong arguments have been made to defer the Ross-Konno where possible
; however, there is insufficient evidence to support this approach over primary Ross-Konno. In our center, early balloon aortic valvuloplasty is the favored initial approach for isolated aortic stenosis, with later Ross and/or Ross-Konno when needed.
Early postoperative management is not complex, with most patients demonstrating satisfactory cardiac performance in the operating room, including most patients whose ventricular function has been depressed because of critical obstruction. Left atrial pressure monitoring and delayed sternal closure are appropriate adjuncts when needed. Mild compromise in cardiac output over the first 24 hours can be anticipated and managed in the usual way for patients with 2 ventricles. In situations where the ventricular function is poor, despite an apparently good technical result, a planned period of support on ECMO initiated in the operating room is superior to severe low cardiac output syndrome and sequelae, particularly the requirement for emergent cannulation.
Several technical highlights warrant discussion: (1) In most cases, the Konno incision simply needs to break the annular ring, and large septal incisions are not required as long as there is no fibrous restriction of the outflow. Large septal incisions may be associated with ventricular dysfunction, (2) During the autograft harvesting, it is usual to have some redundant right ventricular muscle anteriorly that can be used to augment the Konno ventricular incision
and correctly orients the autograft. In most cases, this is a useful structural and hemostatic adjunct to the operation. Excessive tissue should not be translocated as it raises the level of the autograft and prevents intra-annular placement of the autograft, (3) Although possible to place the autograft simply “on top” of the aortic annulus, we highlight the importance of placing the autograft at the annular level. This may support the autograft and reduce the likelihood of dilatation. It also ensures that the coronary arteries can be implanted at the appropriate level, (4) In our experience, the mismatch between the aortic and pulmonary annular sizes has not been a hazard for coronary artery implantation. Mobilization of the epicardial course of the coronary artery to create a generous trumpet of aortic tissue allows effective coronary transfer. This is most relevant when a Ross-Konno is done as a primary or secondary procedure in the context of aortic interruption with VSD with left ventricular outflow tract obstruction.
The long-term performance of the autograft and interventions required across the lifespan for a neonate requiring intervention on the aortic remains a concern. Whereas in older patients, the primary shortcoming of the Ross is a relatively high requirement for autograft reinterventions due to dilatation of the neoaortic root and the development of aortic valve incompetence, autografts placed in neonates and infants seem to be less affected by this issue.
The median follow-up times in most reported series are between 3 and 8 years, during which the neo-aortic root demonstrates proportional somatic growth without excessive dilatation. Longitudinal studies are required to assess neo-aortic root size and development of valvar incompetence beyond the medium term. There are also concerns about the potential for the left ventricular dys-synchrony and dysfunction,
Right-sided interventions are an important source of re-intervention. Although the Ross procedure places a homograft in an orthotopic position which is associated with excellent long-term freedom from reoperation on the right side in adults,
The developing utility of percutaneous valves may reduce the number of operations required; however, not all conduits are suitable, and the proximity of the left coronary artery to the posterior aspect of the original conduit may cause significant coronary artery compression. Lifetime planning is required, with a mix of open and percutaneous interventions tailored to the individual.
Conclusions
The Ross-Konno procedure delivers a high-quality left ventricular outflow with acceptable perioperative risk and good medium-term outcomes when performed in neonates and infants. Technical aspects are similar to approaches used in adults, although a higher proportion of neonates and infants come to the procedure semi-urgently and with concomitant lesions. The ideal timing of this operation vs conservative approaches and other forms of valve replacement is not yet defined.
References
El-Hamamsy I
Toyoda N
Itagaki S
et al.
Propensity-matched comparison of the ross procedure and prosthetic aortic valve replacement in adults.
Dorobantu DM, Taliotis D, Tulloh RM, et al. Surgical versus balloon valvotomy in neonates and infants: results from the UK National Audit. Open Hear. 2019;6:e000938. https://doi.org/10.1136/openhrt-2018-000938
In 1967 Donald Ross first described the use of a transplanted pulmonary autograft to replace an aortic valve in twelve patients stating that “As a living autograft, the transplanted pulmonary valve has the prospect of long-term or permanent survival, whilst retaining the advantages of an aortic homograft” the latter being the prevailing implant for aortic valve replacement at that time.1 Fast forward 55 years later, Mr. Ross’ prediction of long-term or permanent survival of the autograft remains controversial, particularly as it is applied to young and rapidly growing children and young infants who arguably would benefit the most from his procedure.
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