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Mechanical Circulatory Support Following Norwood Palliation

2016; Elsevier BV; Volume: 21; Issue: 4 Linguagem: Inglês

10.1053/j.optechstcvs.2017.09.002

1532-8627

Pirooz Eghtesady, Peter B. Manning,

Cardiac Structural Anomalies and Repair

Historically, mechanical circulatory support for the newborn, particularly those with a single-ventricle physiology, such as hypoplastic left heart syndrome, has been limited to extracorporeal membrane oxygenation. The results using extracorporeal membrane oxygenation have been less than optimal, and the application of the Berlin Heart, the only pediatric ventricular assist device the Food and Drug Administration has approved to date, has also been unsuccessful. We present a compilation of techniques that can be applied to these infants. The key principle revolves around the cannulation technique (and cannula used), which involves the placement of an "aortic" cannula flush with the surface of the common atrium (avoiding any extracorporeal surface exposure within the heart chambers). Further, the application of a centrifugal pump allows for a quite effective decompression of the heart in this setting. Lastly, the described approach allows the provision of support in a rather simple fashion without the use of cardiopulmonary bypass support and without the need for a ventriculotomy. Historically, mechanical circulatory support for the newborn, particularly those with a single-ventricle physiology, such as hypoplastic left heart syndrome, has been limited to extracorporeal membrane oxygenation. The results using extracorporeal membrane oxygenation have been less than optimal, and the application of the Berlin Heart, the only pediatric ventricular assist device the Food and Drug Administration has approved to date, has also been unsuccessful. We present a compilation of techniques that can be applied to these infants. The key principle revolves around the cannulation technique (and cannula used), which involves the placement of an "aortic" cannula flush with the surface of the common atrium (avoiding any extracorporeal surface exposure within the heart chambers). Further, the application of a centrifugal pump allows for a quite effective decompression of the heart in this setting. Lastly, the described approach allows the provision of support in a rather simple fashion without the use of cardiopulmonary bypass support and without the need for a ventriculotomy. Despite medical and surgical advances, two-thirds of neonates who have undergone Norwood stage I palliation for single-ventricle anomalies survive infancy without transplant. The 2014 report from the multi-institutional Single Ventricle Reconstruction (SVR) trial showed 64% 3-year transplant-free survival at 15 high-volume and experienced centers.1Newburger J.W. Sleeper L.A. Frommelt P.C. et al.Transplantation-free survival and interventions at 3 years in the single ventricle reconstruction trial.Circulation. 2014; 129: 2013-2020Crossref PubMed Scopus (145) Google Scholar For patients with failing physiology, extracorporeal membrane oxygenation (ECMO) has been the primary method of mechanical circulatory support as a bridge to buy time until transplantation. Attempts have also been made to "unload" the ventricle with salvage bidirectional Glenn palliation, but rarely has this approach been successful enough to avoid transplantation. Overall poor outcomes2Sherwin E.D. Gauvreau K. Scheurer M.A. et al.Extracorporeal membrane oxygenation after stage 1 palliation for hypoplastic left heart syndrome.J Thorac Cardiovasc Surg. 2012; 144: 1337-1343Abstract Full Text Full Text PDF PubMed Scopus (83) Google Scholar, 3Fernandez R.P. Joy B.F. Allen R. et al.Interstage survival for patients with hypoplastic left heart syndrome after ECMO.Pediatr Cardiol. 2017; 38: 50-55Crossref PubMed Scopus (9) Google Scholar following these approaches have led to a generally pessimistic view of ECMO and any other measures to rescue the failing single-ventricle patient with a shunt-dependent circulation. In a recent review of data from the investigational device exemption trial of the Berlin Heart EXCOR device (the only circulatory support device other than ECMO currently approved for use in children), only 1 out of 9 infants with single-ventricle physiology and shunt-dependent pulmonary blood flow survived to transplantation.4Weinstein S. Bello R. Pizarro C. et al.The use of the Berlin Heart EXCOR in patients with functional single ventricle.J Thorac Cardiovasc Surg. 2014; 147: 697-705Abstract Full Text Full Text PDF PubMed Scopus (166) Google Scholar Shunt-dependent single-ventricle patients are particularly challenging to support with these devices partly because both systemic and pulmonary blood flow must be supported with a single-support device, often exceeding the flow capabilities of systems designed to supply only systemic circulation. Beginning in 2011, our group began to implement alternative approaches for supporting these infants using centrifugal mechanical circulatory support systems. Specifically, we set goals to avoid the use of an oxygenator (to decrease resistance within the circuitry and hence to allow greater flows) and to cannulate in a way that would allow chest closure for an improved chronic rehabilitation of patients. The operative technique is described in detail as follows (Figure 1, Figure 2, Figure 3, Figure 4, Figure 5).Figure 1(A, B) Initially, we used standard bypass cannulas, recapitulating some adult experience for temporary support. This was obviously a simple procedure and easily implemented even during the index Norwood procedure. The cannulas could be externalized after securing them to the edges of the native pericardium inside the chest (in addition to the usual sutures on the outside) (A). We could achieve the high flows necessary for adequate support of these infants (up to cardiac index of ~6 to 7 L/min/m2). This approach, however, had a significant limitation mainly because of thromboembolic events likely from clot burden within and surrounding the cannulas. It was clear from these early cases, as well as from our experience with paracorporeal lung assist devices,5Hoganson D.M. Gazit A.Z. Sweet S.C. et al.Neonatal paracorporeal lung assist device for respiratory failure.Ann Thorac Surg. 2013; 95: 692-694Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar that the cannula design was the rate-limiting step to successful support. Specifically, the large cannula tip within the relatively small atrium leads to a large thrombogenic surface area, and any "cul de sacs" devoid of moving blood (eg, between the cannula edge and the atrial wall or the residual septum, B) could also be a nidus for clot formation despite adequate anticoagulation. The alternative of introducing a smaller portion of the cannula into the atrium would likely create much angst with a possible dislodgement.Show full caption(C, D) For this reason, in the next evolution of this approach, 5-mm ringed GORE-TEX grafts were sewn to the neo-Ao or dunked into the common atrium; the grafts were then tunneled through the skin allowing chest closure (C). Femoral arterial cannulas (14 Fr) were then introduced into these inflow and outflow grafts to provide support. For the purposes of this report, the descriptions of "inflow" and "outflow" follow the same convention as that used in terminology related to assist devices: inflow cannula refers to that which draws blood into the pump from the heart, whereas outflow cannula refers to that which conveys blood from the pump to the ascending Ao. In cases where we anticipate a high likelihood of needing support post Norwood (eg, significant preoperative tricuspid regurgitation), then a 5-mm ringed GORE-TEX graft is sewn to the homograft patch before arch reconstruction. The graft is temporarily clipped and used only in case mechanical support is needed at the end of the case. If the intent is to leave the operating room with these grafts clipped (for possible use in the later postoperative period), it is critical that the grafts are clipped flush with the anastomotic surface to avoid the formation of a thrombus in the graft. It is critical to introduce the venous cannula in the inflow limb all the way up to the site of entry of the GORE-TEX graft into the atrium. Otherwise, the walls of the graft will get sucked down with the initiation of support. Lastly, at least 2 cm of the GORE-TEX graft should be protruding through the skin exit site to allow a reasonable handle for manipulation or removal of the cannulas from the graft. An alternative strategy that we have recently pursued is to attach the GORE-TEX outflow graft to the descending Ao because we routinely cannulate this structure during the Norwood procedure (D). This procedure would make it easier to remove the cannulas postoperatively even when the chest is closed. With these GORE-TEX graft extensions, we have not had thromboembolic events that we observed using the standard bypass cannula. The use of GORE-TEX extensions with bypass cannulas potentially allows the exchange of the cannulas in case of concerns with clot buildup and avoids the primary problem of a large plastic surface protruding in the middle of the common atrium. Further, these extensions facilitate the implementation of support for very small babies in whom larger-size ready-made or off-the-shelf cannulas become challenging. There are limitations, however, with these composite GORE-TEX bypass cannulations as well. After about a week, the cannulas become quite stuck within the grafts, and for that reason, we evolved to the use of Berlin Heart cannulas when anticipating prolonged support (months). The Berlin Heart cannulas are specifically designed for long-term use in a paracorporeal fashion. Ao = aorta.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 2In our experience, 50% of the single-ventricle infants referred for heart failure management are already on ECMO when they were sent to our institution. In nearly all these instances, the patients had been cannulated via a cervical approach. Although these peripheral ECMO cannulas are limited in how much support they can provide, the ECMO configuration does allow for oxygenation of the neonate, which would otherwise not be feasible with the right ventricle-to-pulmonary artery (RV-to-PA) shunt configuration, the case for all of our referrals thus far. For this reason, our first step involves the creation of a systemic to pulmonary artery shunt from the innominate artery to the right pulmonary artery. The RV-to-PA conduit is then divided so that as much of the native cardiac output is directed systemically (A). BT = blalock-taussig.Show full caption(B) Alternatively, the RV-to-PA conduit can be disconnected from its attachment to the right ventricle and sewn to the side of the polytetrafluoroethylene graft that is attached to the Berlin outflow cannula; this approach, however, requires the composite graft attached to the Berlin cannula to be longer, otherwise can lead to a potential kinking of the graft at the anastomosis.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 3Unfortunately, the 5-mm EXCOR arterial cannula is no longer manufactured in United States, which would be ideal for a smaller baby (~2.5 kg). Therefore, in most instances, we attach the 6-mm EXCOR arterial cannula with a short (~1 cm) polytetrafluoroethylene extension (8-mm graft) to the neo-Ao (A). The 8-mm graft is stretched using serial Hegar dilators up to 10 mm, which allow for a snug fit of the GORE-TEX extension to the cannula tip. Although implantation onto the homograft patch along the inner curve near the lower aspect of the neo-Ao reconstruction may be easier, placement on the greater curve a centimeter or 2 below the innominate artery takeoff leads to a better flow directed down the arch. This approach is obviously restricted to those who are more remote from their Norwood procedure so that one is not dealing with proximity to the suture line between the patch and the diminutive ascending Ao. The preferred position of the cannula along the outer curve of neo-Ao ensures that the inflow jet is not directed at the innominate artery, which can give rise to an inadvertently high Qp-to-Qs ratio; we observed this unusual phenomenon in a couple of patients (in whom the cannula had been placed on the medial side of the neo-Ao) as an incidental finding during a subsequent cardiac catheterization. Similarly, when using the Berlin arterial cannula, it is important that the angulation of the cannula or composite graft is not directed toward the neoaortic valve to avoid neoaortic valve insufficiency. In patients who have undergone a hybrid approach, a modified approach can be implemented. Ao = aorta; Pa = pulmonary artery.Show full caption(B) After the placement of bands on the left and then the right branch pulmonary arteries, a 10-mm graft is sewn to the distal MPA just before the takeoff of the ductus. In this instance, we use a 10-mm graft (instead of 8 mm) because serial dilations of the graft are not feasible after the attachment to the pulmonary artery.(C) The ductal stent is then placed through this graft in standard fashion.(D) Finally, a clamp is applied to the base of the graft and the aortic cannula is sewn to the graft with 4 separate 5.0 Prolene sutures (at 4 quadrants: 3, 6, 9, and 12 o'clock). The graft is further secured with a 2.0 silk tie placed around the flange of the cannula over the GORE-TEX graft. This construction ends up being slightly longer than when the composite is created before sewing the graft to the pulmonary artery simply because there is less ability to manipulate the graft after it is sewn to the pulmonary artery. In this instance, it is critical to ensure the GORE-TEX graft does not rotate or move much; a suture can be applied to the sewing cuff of the cannula and then tack that down onto the MPA if the natural lie seems likely to lead to rotation and a possible kinking of the GORE-TEX portion. The cannula is deaired and then tunneled through the abdominal wall. MPA = main pulmonary artery.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 3Unfortunately, the 5-mm EXCOR arterial cannula is no longer manufactured in United States, which would be ideal for a smaller baby (~2.5 kg). Therefore, in most instances, we attach the 6-mm EXCOR arterial cannula with a short (~1 cm) polytetrafluoroethylene extension (8-mm graft) to the neo-Ao (A). The 8-mm graft is stretched using serial Hegar dilators up to 10 mm, which allow for a snug fit of the GORE-TEX extension to the cannula tip. Although implantation onto the homograft patch along the inner curve near the lower aspect of the neo-Ao reconstruction may be easier, placement on the greater curve a centimeter or 2 below the innominate artery takeoff leads to a better flow directed down the arch. This approach is obviously restricted to those who are more remote from their Norwood procedure so that one is not dealing with proximity to the suture line between the patch and the diminutive ascending Ao. The preferred position of the cannula along the outer curve of neo-Ao ensures that the inflow jet is not directed at the innominate artery, which can give rise to an inadvertently high Qp-to-Qs ratio; we observed this unusual phenomenon in a couple of patients (in whom the cannula had been placed on the medial side of the neo-Ao) as an incidental finding during a subsequent cardiac catheterization. Similarly, when using the Berlin arterial cannula, it is important that the angulation of the cannula or composite graft is not directed toward the neoaortic valve to avoid neoaortic valve insufficiency. In patients who have undergone a hybrid approach, a modified approach can be implemented. Ao = aorta; Pa = pulmonary artery.Show full caption(B) After the placement of bands on the left and then the right branch pulmonary arteries, a 10-mm graft is sewn to the distal MPA just before the takeoff of the ductus. In this instance, we use a 10-mm graft (instead of 8 mm) because serial dilations of the graft are not feasible after the attachment to the pulmonary artery.(C) The ductal stent is then placed through this graft in standard fashion.(D) Finally, a clamp is applied to the base of the graft and the aortic cannula is sewn to the graft with 4 separate 5.0 Prolene sutures (at 4 quadrants: 3, 6, 9, and 12 o'clock). The graft is further secured with a 2.0 silk tie placed around the flange of the cannula over the GORE-TEX graft. This construction ends up being slightly longer than when the composite is created before sewing the graft to the pulmonary artery simply because there is less ability to manipulate the graft after it is sewn to the pulmonary artery. In this instance, it is critical to ensure the GORE-TEX graft does not rotate or move much; a suture can be applied to the sewing cuff of the cannula and then tack that down onto the MPA if the natural lie seems likely to lead to rotation and a possible kinking of the GORE-TEX portion. The cannula is deaired and then tunneled through the abdominal wall. MPA = main pulmonary artery.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 4Placement of the common atrial cannula is perhaps the most critical step in this configuration because inflow or venous drainage is typically the major determinant of the flow capacity of a mechanical circulatory support system. We again use a 6-mm (luminal dimension) Berlin Heart arterial cannula for this purpose up to 3-4 months of age. For the larger or older infant, we will consider the use of a 9-mm cannula. A key step is to ensure none of the atrial wall tissue obstructs the lumen of the cannula, particularly given the relatively short lip of this cannula. Often the atrium is big enough that a side-biting clamp can be safely applied, allowing a controlled atriotomy of appropriate size (A).Show full caption(B) To accomplish this, an over-and-over sewing of the atrial edge with a 5.0 Prolene suture ensures the tissue fold into the lumen of the cannula. In the very young, this step is not necessary because typically the atrial tissue is quite thin. If the heart is arrested (for purposes of performing some intracardiac procedure), then the introduction of the cannula can easily be performed on the "way out." Alternatively, 1 of 2 different approaches can be used for insertion either off pump or with ECMO support. If there is adequate atrial tissue that can be occluded within the side-biting clamp, then one can easily proceed with the next step.(C) A series of pledgeted 5.0 Prolene sutures are placed circumferentially around the opening and passed through the sewing cuff of the cannula and tied down. A running technique can also be implemented and is faster, but in our experience, the interrupted technique appears to be more hemostatic. The cannula is then filled with blood in retrograde fashion and then passed through a tunnel created in the subxiphoidal area. This is particularly critical for the inflow cannula as deairing is not particularly effective or feasible once it has been tunneled through abdominal wall.(D) Alternatively, if there is not enough room for the application of a side-biting clamp, then the following approach can be implemented. The edges of the cannula are painted with a marker pen and then this cannula is applied onto the surface of the atrium to create a mark approximating the size of the opening necessary for allowing the introduction of the cannula. This method will guide the length of the incision to be made, which should be larger than the size of the marked spot to decrease the chances of the cannula falling out or bleeding during this maneuver. Four or 5 pledgeted sutures are placed around the circumference of the mark and brought up through the sewing cuff circumferentially. A few of these sutures are then passed through a snare, ready to be cinched down as needed. A stab incision is then made (while ventilation is being held) and the cannula is quickly slipped into the hole. While the cannula is being held against the atrial wall by the assistant, the previously placed sutures are tied down. Additional sutures can be applied either individually or in a running technique to further secure the cannula in place. A safety tourniquet suture line can be placed in case the cannula slips out to protect against significant bleeding. Once again, the cannula is filled with blood and passed in a retrograde fashion through the subxiphoid space.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 5Infants and newborns can be quite active particularly with the Berlin Heart and the composite GORE-TEX graft configurations described here. The exit sites do not appear to cause any discomfort for them as the babies can easily lay prone on these cannulas (and without any change in the flow patterns of the device). Early after insertion, the infants require quite high pump flows (confidence interval of 6-7 L/min/m2). Often the amount of support needed decreases with time perhaps in part because of some recovery of a native cardiac function that we have invariably seen in all infants despite the grave magnitude of dysfunction early on. Despite the relatively long segment of tubing outside the body (~3 to 4 ft), there is no thermoregulation problems in these infants. We follow a regimen of heparin (initially infusion followed by transition to Lovenox with an anti-Xa goal-directed titration) and aspirin anticoagulation. We aggressively pursue normal oral feeding in these infants and have concerns when such progress is not made; we have a low threshold to perform cardiac catheterization as well as computed tomography angiography to assess the anatomy and hemodynamics in these circumstances. The infants should thrive and have a correction of their weight-for-age z-scores typically within a month. (Color version of figure is available online at www.optechtcs.com.)View Large Image Figure ViewerDownload Hi-res image Download (PPT) (C, D) For this reason, in the next evolution of this approach, 5-mm ringed GORE-TEX grafts were sewn to the neo-Ao or dunked into the common atrium; the grafts were then tunneled through the skin allowing chest closure (C). Femoral arterial cannulas (14 Fr) were then introduced into these inflow and outflow grafts to provide support. For the purposes of this report, the descriptions of "inflow" and "outflow" follow the same convention as that used in terminology related to assist devices: inflow cannula refers to that which draws blood into the pump from the heart, whereas outflow cannula refers to that which conveys blood from the pump to the ascending Ao. In cases where we anticipate a high likelihood of needing support post Norwood (eg, significant preoperative tricuspid regurgitation), then a 5-mm ringed GORE-TEX graft is sewn to the homograft patch before arch reconstruction. The graft is temporarily clipped and used only in case mechanical support is needed at the end of the case. If the intent is to leave the operating room with these grafts clipped (for possible use in the later postoperative period), it is critical that the grafts are clipped flush with the anastomotic surface to avoid the formation of a thrombus in the graft. It is critical to introduce the venous cannula in the inflow limb all the way up to the site of entry of the GORE-TEX graft into the atrium. Otherwise, the walls of the graft will get sucked down with the initiation of support. Lastly, at least 2 cm of the GORE-TEX graft should be protruding through the skin exit site to allow a reasonable handle for manipulation or removal of the cannulas from the graft. An alternative strategy that we have recently pursued is to attach the GORE-TEX outflow graft to the descending Ao because we routinely cannulate this structure during the Norwood procedure (D). This procedure would make it easier to remove the cannulas postoperatively even when the chest is closed. With these GORE-TEX graft extensions, we have not had thromboembolic events that we observed using the standard bypass cannula. The use of GORE-TEX extensions with bypass cannulas potentially allows the exchange of the cannulas in case of concerns with clot buildup and avoids the primary problem of a large plastic surface protruding in the middle of the common atrium. Further, these extensions facilitate the implementation of support for very small babies in whom larger-size ready-made or off-the-shelf cannulas become challenging. There are limitations, however, with these composite GORE-TEX bypass cannulations as well. After about a week, the cannulas become quite stuck within the grafts, and for that reason, we evolved to the use of Berlin Heart cannulas when anticipating prolonged support (months). The Berlin Heart cannulas are specifically designed for long-term use in a paracorporeal fashion. Ao = aorta. (B) Alternatively, the RV-to-PA conduit can be disconnected from its attachment to the right ventricle and sewn to the side of the polytetrafluoroethylene graft that is attached to the Berlin outflow cannula; this approach, however, requires the composite graft attached to the Berlin cannula to be longer, otherwise can lead to a potential kinking of the graft at the anastomosis. (B) After the placement of bands on the left and then the right branch pulmonary arteries, a 10-mm graft is sewn to the distal MPA just before the takeoff of the ductus. In this instance, we use a 10-mm graft (instead of 8 mm) because serial dilations of the graft are not feasible after the attachment to the pulmonary artery. (C) The ductal stent is then placed through this graft in standard fashion. (D) Finally, a clamp is applied to the base of the graft and the aortic cannula is sewn to the graft with 4 separate 5.0 Prolene sutures (at 4 quadrants: 3, 6, 9, and 12 o'clock). The graft is further secured with a 2.0 silk tie placed around the flange of the cannula over the GORE-TEX graft. This construction ends up being slightly longer than when the composite is created before sewing the graft to the pulmonary artery simply because there is less ability to manipulate the graft after it is sewn to the pulmonary artery. In this instance, it is critical to ensure the GORE-TEX graft does not rotate or move much; a suture can be applied to the sewing cuff of the cannula and then tack that down onto the MPA if the natural lie seems likely to lead to rotation and a possible kinking of the GORE-TEX portion. The cannula is deaired and then tunneled through the abdominal wall. MPA = main pulmonary artery. (B) After the placement of bands on the left and then the right branch pulmonary arteries, a 10-mm graft is sewn to the distal MPA just before the takeoff of the ductus. In this instance, we use a 10-mm graft (instead of 8 mm) because serial dilations of the graft are not feasible after the attachment to the pulmonary artery. (C) The ductal stent is then placed through this graft in standard fashion. (D) Finally, a clamp is applied to the base of the graft and the aortic cannula is sewn to the graft with 4 separate 5.0 Prolene sutures (at 4 quadrants: 3, 6, 9, and 12 o'clock). The graft is further secured with a 2.0 silk tie placed around the flange of the cannula over the GORE-TEX graft. This construction ends up being slightly longer than when the composite is created before sewing the graft to the pulmonary artery simply because there is less ability to manipulate the graft after it is sewn to the pulmonary artery. In this instance, it is critical to ensure the GORE-TEX graft does not rotate or move much; a suture can be applied to the sewing cuff of the cannula and then tack that down onto the MPA if the natural lie seems likely to lead to rotation and a possible kinking of the GORE-TEX portion. The cannula is deaired and then tunneled through the abdominal wall. MPA = main pulmonary artery. (B) To accomplish this, an over-and-over sewing of the atrial edge with a 5.0 Prolene suture ensures the tissue fold into the lumen of the cannula. In the very young, this step is not necessary because typically the atrial tissue is quite thin. If the heart is arrested (for purposes of performing some intracardiac procedure), then the introduction of the cannula can easily be performed on the "way out." Alternatively, 1 of 2 different approaches can be used for insertion either off pump or with ECMO support. If there is adequate atrial tissue that can be occluded within the side-biting clamp, then one can easily proceed with the next step. (C) A series of pledgeted 5.0 Prolene sutures are placed circumferentially around the opening and passed through the sewing cuff of the cannula and tied down. A running technique can also be implemented and is faster, but in our experience, the interrupted technique appears to be more hemostatic. The cannula is then filled with blood in retrograde fashion and then passed through a tunnel created in the subxiphoidal area. This is particularly critical for the inflow cannula as deairing is not particularly effective or feasible once it has been tunneled through abdominal wall. (D) Alternatively, if there is not enough room for the application of a side-biting clamp, then the following approach can be implemented. The edges of the cannula are painted with a marker pen and then this cannula is applied onto the surface of the atrium to create a mark approximating the size of the opening necessary for allowing the introduction of the cannula. This method will guide the length of the incision to be made, which should be larger than the size of the marked spot to decrease the chances of the cannula falling out or bleeding during this maneuver. Four or 5 pledgeted sutures are placed around the circumference of the mark and brought up through the sewing cuff circumferentially. A few of these sutures are then passed through a snare, ready to be cinched down as needed. A stab incision is then made (while ventilation is being held) and the cannula is quickly slipped into the hole. While the cannula is being held against the atrial wall by the assistant, the previously placed sutures are tied down. Additional sutures can be applied either individually or in a running technique to further secure the cannula in place. A safety tourniquet suture line can be placed in case the cannula slips out to protect against significant bleeding. Once again, the cannula is filled with blood and passed in a retrograde fashion through the subxiphoid space. We have managed 10 post-Norwood patients with the variety of the configurations described here (9 after stage I palliation and 1 following hybrid palliation); there have been 5 other non-hypoplastic left heart syndrome single-ventricle patients, suggesting the potential application to other lesion sets. As noted previously, 50% of the patients were on ECMO at the time of implant; 40% had renal failure. In all instances, full support could be provided without complications until the decision regarding the plan of care was final (recovery, transplant, or redirection of care) for a median duration of 52 days (range 3-96 days). In summary, the described approaches have a number of advantages not previously achievable in this subset of patients. Most importantly, with this approach, the patient is cannulated via the atrium, as opposed to the ventricle, which requires much less intraoperative dissection and eliminates the need for the excision of obstructive muscle bundles and chordae frequently encountered in the morphologic right ventricle. By avoiding cardiopulmonary bypass, we have had minimal postoperative bleeding and, hence, less blood product exposure, which likely is beneficial for an infant under consideration for transplantation. The modification (with GORE-TEX connections, W. L. Gore & Associates, Inc. Flagstaff, Arizona) also has the advantage of allowing chest closure immediately following the Norwood procedure. Lastly, achieving the high flows necessary to support both systemic and pulmonary blood flows overcomes the main limitation of peripheral ECMO cannulation in these infants. The ease with which the procedures can be carried out has led to our routine adoption of these techniques for our high-risk patients.