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Neonatal Management of Congenital Heart Disease
Introduction
Neonates with congenital heart disease require a well-integrated and multidisciplinary team approach to achieve optimal outcomes. The complexity of managing a critically ill newborn is compounded greatly when the cardiovascular physiology and/or anatomy are significantly altered. Many of the important management principles routinely followed by neonatologists can be applied to critically ill newborn cardiac patients, including thermal regulation, prematurity issues, nutritional strategies, and ventilator support. However, cardiac-specific management strategies, procedures, and surgeries are often required during the neonatal period for patients with congenital heart disease (CHD). These unique strategies must be understood and carefully integrated into the management plan. The objective of this chapter is to describe these management strategies and procedures typically performed based on the prevailing anatomic or physiologic deficit faced by the infant during the neonatal period, as opposed to each specific anatomic variant of CHD. Since many of these conditions have similar underlying physiologies as well as early goals for palliation or treatment, the strategies employed can be applied to many different disease conditions.
As described in earlier chapters, the vast majority of congenital heart conditions (e.g., small ventricular septal defects [VSD] or bicuspid aortic valves) either do not require any interventions whatsoever or require interventional or surgical procedures later in infancy or early childhood. Although patients in the latter category may be managed in the neonatal ICU or co-managed with the pediatric cardiology service, their clinical courses are often straightforward and team discussions are typically focused on the anticipated follow-up and postdischarge planning. Examples of such conditions include the “pink” tetralogy of Fallot patient that will undergo surgical repair at 4-6 months of age or the mild valvar pulmonary stenosis patient that develops worsening obstruction in the coming months requiring balloon pulmonary valvuloplasty. This chapter focuses on congenital heart disease typically requiring medical management, catheter-based interventions, or surgeries in the neonatal period. It describes current approaches to moderate and severe forms of congenital heart disease in which neonatal palliation or treatment is required to avoid early mortality or long-term disability. The chapter also discusses those situations in which early intervention would not alter clinical course and for which the best course of management may be cardiac transplantation or palliative comfort measures.
Moderate and severe forms of congenital heart disease can be largely grouped as cyanotic and acyanotic conditions ( Table 78.1 ). Within these major silos, conditions can also be classified based on the degree of pulmonary blood flow and whether or not they are dependent on the patent ductus arteriosus (PDA) for either pulmonary or systemic blood flow. By classifying these conditions in this manner, neonatologists will be able to more readily identify the major physiologic deficit and anticipate necessary treatment options. For patients requiring surgery in the neonatal period, the focus within this chapter is on the indications and types of surgery that can be offered. The postoperative management of these patients is not discussed, as a detailed description of the theories and summary of available evidenced-based practice is outside the scope of this chapter.
TABLE 78.1
Physiologic Classification of Congenital Heart Disease
| Cyanotic | Acyanotic | |||
|---|---|---|---|---|
| Right-side Obstruction | Admixture Lesions | Transposition Physiology |
Left-side Obstruction | Left-to-right Shunts |
| Pulmonary atresia with intact ventricular septum Pulmonary atresia, VSD, and MAPCAs Pulmonary stenosis Tetralogy of Fallot |
Common atrium
Double inlet left ventricle Double outlet right ventricle |
Transition of the great arteries | Aortic stenosis Coarctation of the aorta Interrupted aortic arch |
Atrial septal defect
Atrioventricular septal defect |
MAPCA, Major aortopulmonary collateral arteries; VSD, ventricular septal defect.
Cyanotic Congenital Heart Conditions
Cyanotic congenital heart disease (CCHDs) includes a broad class of anatomic and physiologic derangements that result in patients with decreased systemic oxygenation following birth, including 1) obstruction to pulmonary blood flow with an intracardiac shunt such as an atrial septal defect (ASD) or VSD or 2) admixture lesions in which there is a common site for mixing of systemic and pulmonary venous blood (atria or ventricles) which is pumped to both circulations, 3) transposition physiology in which systemic venous blood is pumped to the systemic circulation, 4) pure right to left shunting (e.g., pulmonary arteriovenous (AV) malformations). The first three broad categories are more frequently encountered in the neonatal period and will be discussed more in the coming sections. The therapies required for palliation or repair of CCHDs differ tremendously within these three classes depending on other anatomic variations that are present. For example, in the admixture lesion tricuspid atresia, pulmonary blood flow is determined by the size of the VSD and relationship of the great arteries. If the VSD is large and the great arteries are normally related (i.e., the pulmonary artery arises off the rudimentary right ventricle), there is normal to increased pulmonary blood flow. This infant's oxygen level will be fairly normal in the neonatal period. However, if the VSD is restrictive and/or the great arteries are transposed (i.e., the pulmonary artery is remote from the VSD and right ventricle), pulmonary blood flow can be considerably limited, resulting in significantly low oxygen levels in the absence of a PDA. Therefore, as we discuss cyanotic congenital heart disease palliation and treatment, the following sections focus more on the immediate goals required to stabilize, palliate, or definitively treat patients in the neonatal period, including approaches for maintaining patency of the ductus arteriosus and less on the specific type of CCHD. Historically, most of these conditions requiring neonatal treatment were managed in the operating room, including a number of surgeries still currently performed ( Table 78.2 ). However, advancements in device technology and increasingly available devices small enough for neonatal use, has led to an increasing number of CCHD that are treated via transcatheter interventions ( Table 78.3 ).
TABLE 78.2
Common Named Cardiac Operations Performed in Infants
| Named Surgery | Surgical Description | Purpose |
|---|---|---|
| Norwood | Anastomosis of PA to hypoplastic ascending aorta, arch augmentation | Create new “aorta” from pulmonary trunk and patch |
| Damus-Kaye-Stansel | Anastomosis of PA to ascending aorta | Combine great arteries for systemic flow to bypass subaortic obstruction |
| Blalock-Taussig shunt | Gore-Tex tube from subclavian artery to PA | Supply pulmonary blood flow |
| Sano shunt | Gore-Tex tube from the RV to PA | Supply pulmonary blood flow |
| Bidirectional Glenn | Anastomosis between SVC and PAs | Supply low-pressure pulmonary blood flow |
| Fontan | Anastomosis between IVC and PAs | Supply low-pressure pulmonary blood flow |
| Jatene | Arterial switch for d-transposition of the great arteries | Anatomical correction |
| Rastelli | VSD closure and RV-PA conduit placement | Create new “main pulmonary artery” |
IVC, Inferior vena cava; PA, pulmonary artery; RV, right ventricle; SVC, superior vena cava; VSD, ventricular septal defect.
TABLE 78.3
Neonatal Cardiac Lesions and Typical Catheter-Based Therapy
| Primary Problem | Hemodynamic Etiology | Defects | Intervention(s) | Result |
|---|---|---|---|---|
| Cyanosis | Atrial septal restriction | d-TGA with restrictive atrial septum | Balloon atrial septostomy | Improvement in atrial mixing and oxygen saturation |
| Decreased pulmonary blood flow | Critical pulmonary stenosis Pulmonary atresia TOF |
Balloon pulmonary valvuloplasty Valve perforation and valvuloplasty RVOT stenting PDA stenting BT shunt balloon dilation and/or stenting |
Improvement in pulmonary blood flow and oxygen saturation | |
| Left-sided obstruction | Left ventricular outflow tract obstruction | Critical aortic stenosis
Critical coarctation |
Balloon aortic valvuloplasty Angioplasty/stenting of coarctation |
Decrease left-sided obstruction |
| Decreased cardiac output | Pulmonary overcirculation causing congestive heart failure | Patent ductus arteriosus Atrial septal defect * Ventricular septal defect |
Device closure * | Eliminate or decrease left-to-right shunt |
| Vascular obstruction | SVC syndrome | Typically iatrogenic | Angioplasty and/or stent * | Unobstructed flow |
BT, Blalock-Taussig; HLHS, hypoplastic left heart syndrome; PA, pulmonary artery; PV, pulmonary vein; RVOT, right ventricular outflow tract; SV, single ventricle; SVC, superior vena cava; TA, tricuspid atresia; TAPVR, total anomalous pulmonary venous return; TGA, transposition of the great arteries; TOF, tetralogy of Fallot.
Procedures to Increase Pulmonary Blood Flow
There are many CCHDs in which obstruction of pulmonary blood flow (PBF) is the underlying etiology for systemic desaturation. The specific anatomic or physiologic issue causing the limited PBF varies considerably and, therefore, the approach to augment pulmonary blood flow is situation dependent. The different methods and approaches used to increase pulmonary blood flow are described in this section.
Balloon Pulmonary Valvuloplasty
Balloon pulmonary valvuloplasty (BPV) was first described by Kan in 1982 and is an effective strategy to increase pulmonary blood flow in patients with either isolated pulmonary valve stenosis or when found in combination in more complex congenital heart disease ( Fig. 78.1 A , B ). Current indications for balloon pulmonary valvuloplasty include patients with either critical pulmonary stenosis (ductal-dependent pulmonary blood flow and/or severe right ventricular dysfunction) or in a patient with a peak instantaneous gradient of ≥40 mm Hg on echocardiography. The procedure typically results in a significant reduction in the pressure gradient across the valve and carries very good mid- and late-term results. A small number of patients will develop significant subvalvar gradient immediately following balloon pulmonary valvuloplasty secondary to significant right ventricular hypertrophy and infundibular narrowing. This temporary obstruction can be managed medically with increased right ventricular volume and beta blockers. Balloon pulmonary valvuloplasty can also be performed in patients with tetralogy of Fallot when the predominant level of obstruction is at the valvar level. This is typically a palliative intervention to allow patients to mature and grow until a complete repair can be done at 4-6 months of age.
Pulmonary Valve Perforation With Balloon Pulmonary Valvuloplasty
Pulmonary atresia with intact ventricular septum is a right-sided obstructive lesion in which there is no antegrade flow from the right ventricle, and pulmonary blood flow is entirely dependent on the PDA. Complete mixing occurs at the atrial level, and all blood is pumped from the left ventricle to the aorta. In this condition, neonates must be started on prostaglandins to maintain ductal patency immediately after birth . If the tricuspid valve and right ventricle are of adequate size, a biventricular repair may be considered. In these situations, patients will be referred to the catheterization laboratory to ensure the coronary arteries fill normally from the aorta and not the hypertensive right ventricle (i.e., not right ventricular–dependent coronary circulation). Pulmonary valve perforation with balloon pulmonary valvuloplasty is indicated in patients with favorable anatomy (membranous atresia) without right ventricular–dependent coronary circulation. This intervention was first reported by Latson in 1991. The technique involves advancing a guidance catheter antegrade from the femoral vein, across the tricuspid valve, and into position directly beneath the atretic pulmonary valve. The optimal target site for perforation is then defined by both right ventricle angiography and aortic angiography, which fills the main pulmonary artery via the PDA. Currently, the most commonly performed method to perforate the membrane is to advance a small radiofrequency (RF) wire within the guide catheter into contact with the membrane. The RF wire delivers a focused energy pulse at the tip to precisely “burn” a small hole in the pulmonary valve membrane. The RF wire is passed through the pulmonary valve membrane into the main pulmonary artery. Perforation can also be accomplished by using a small coronary wire, but the RF wire approach is considered safer and more controlled. Once the valve is perforated and crossed, balloon pulmonary valvuloplasty is performed ( Fig. 78.2 A-D ). This procedure can result in improved antegrade flow from the right ventricle to the pulmonary artery, often allowing for the eventual discontinuation of prostaglandins. This process can sometimes take many weeks before prostaglandins can be discontinued and months before growth of the annulus and entire right ventricular outflow tract is observed. It is not uncommon for patients to require repeat balloon pulmonary valvuloplasty in the first 6 months. If repeat balloon pulmonary valvuloplasty does not result in adequate antegrade pulmonary blood flow, surgical intervention is typically required.
Right Ventricular Outflow Tract Stenting
Severe obstruction of the right ventricular outflow tract (RVOT) can be seen in patients with tetralogy of Fallot and double outlet right ventricle leading to severe cyanosis. Some patients will undergo a complete surgical repair in the neonatal period depending on the patient's weight, size of branch pulmonary arteries, and extracardiac medical issues. Certain centers will perform aortopulmonary shunts (see below) for cyanotic patients with small branch pulmonary arteries and bring them back for complete surgical repair at 4-6 months of age. Balloon pulmonary valvuloplasty is typically not effective in this anatomy given the severe subvalvular obstruction across the right ventricular outflow tract. Over the past 10 years, centers have started palliating these patients by implanting stents across the right ventricular outflow tract. During the procedure, the RVOT and main pulmonary artery are imaged using angiography. The RVOT is then crossed with a catheter, and wire position is established to guide the procedure. A stent is selected based on the size of the right ventricular outflow tract. The stent is advanced over the wire and typically through a long introducer sheath until it is positioned across the RVOT. The stent is deployed within the RVOT and follow-up angiography is then performed to assess the adequacy of antegrade flow through the implanted stent. Multiple stents may need to be placed depending on the anatomy of the right ventricular outflow tract. Most patients maintained on prostaglandins can be weaned off the medication following stent implantation within the right ventricular outflow tract. In premature or small neonates or those with vascular access issues, hybrid per-ventricular stenting of the RVOT, whereby the pediatric heart surgeon places the sheath directly into the right ventricle via a small sub-xiphoid incision, allows effective palliation in this challenging population. In either approach, these stents are removed at the time of surgical repair, which is ultimately delayed to allow for growth in both the patient and branch pulmonary arteries.
Surgical Opening of the Right Ventricular Outflow Tract
In neonates that are not candidates for a complete surgical repair or palliation with balloon angioplasty/stenting of the RVOT, either percutaneously or using hybrid techniques, an open surgical procedure can be used. The operation is performed via a median sternotomy on cardiopulmonary bypass. The goal of the procedure is complete relief of right ventricular outflow tract obstruction whereby the actual technique used depends on the level of obstruction—valvar, supravalvar, or subvalvar—and can range from a simple pulmonary valvotomy or valvectomy to a complete transannular patch opening of the subvalvar, pulmonary valve, and supravalvar regions. The resultant pulmonary insufficiency is usually very well tolerated.
Implantation of a Stent in the Ductus Arteriosus
There are many congenital heart defects in which pulmonary blood flow is dependent on flow via the ductus arteriosus. The most common of these lesions are the more severe cases of tetralogy of Fallot. Additional congenital heart lesions where pulmonary blood flow is dependent on ductal arterial flow includes pulmonary atresia with and without a VSD, double outlet right ventricle with pulmonary atresia, and some forms of tricuspid atresia. The vast majority of these patients are typically treated with surgical palliation, including an aortopulmonary shunt (e.g., modified Blalock-Taussig shunt). Similar to RVOT stenting, advancements in catheter-based technology and techniques have allowed for some of these patients to be palliated by implantation of a stent in the ductus arteriosus. The procedure is typically performed retrograde from the femoral artery or via a vessel off the aortic arch (carotid or axillary artery). The procedure may also be accomplished antegrade from the femoral vein, particularly when there is antegrade flow through the right ventricular outflow tract. The prostaglandin infusion is usually stopped a few hours before the anticipated start of the procedure to allow for some constriction of the ductus arteriosus to occur. Prostaglandins are kept in line in case of severe ductal spasm causing profound cyanosis. Angiography is performed to delineate the length and size of the ductus arteriosus. A guide wire is used to carefully cross the often tortuous ductus arteriosus and used for procedural guidance. An appropriately sized stent is then advanced over the wire and deployed across the ductus arteriosus ( Fig. 78.3 A-C ). This interventional palliation procedure can last many months until the patient can undergo complete surgical repair.
Systemic to Pulmonary Artery Shunts
The ability to augment pulmonary blood flow by a surgically created shunt between the aorta, or one of its branches, and the central pulmonary arteries has a long history dating back to 1945 with the introduction of the Blalock-Taussig (BT) shunt. The classic BT shunt was performed using the divided subclavian artery as an end-to-side anastomosis to the pulmonary artery. Soon other shunt techniques were introduced, such as the Potts shunt, a direct anastomosis between the descending aorta and the left pulmonary artery, and the Waterston shunt, a direct anastomosis between the ascending aorta and the right pulmonary artery. These techniques had in common a shunt that not only augmented pulmonary blood flow but could palliate over a long period of time because of the growth potential of the native tissue construction of the shunt. These shunt techniques are essentially obsolete today for two reasons: 1) with growth of the shunt there is a lack of control over the amount of pulmonary blood flow creating the risk of pulmonary overcirculation, pulmonary vascular disease, and pulmonary hypertension; and 2) the advent of rapid second-stage procedures for successful infant complete repair for two ventricle anatomies or the use of subsequent cavopulmonary shunts for single ventricle anatomies. Therefore, today the most common palliative, neonatal surgical shunt is the modified BT shunt whereby a prosthetic graft is anastomosed proximally end-to-side to the innominate artery or ascending aorta and distally end-to-side to the central pulmonary artery, with flow being controlled by the diameter of the graft chosen, typically 3-4 mm in a neonate.
Procedures to Decrease Pulmonary Blood Flow
In the previous section, the focus was on cyanotic CHD in which pulmonary blood flow is restricted. The conditions described in that section usually tend to make intuitive sense since less pulmonary blood flow is easily reconciled with cyanosis and hypoxia. However, there are forms of cyanotic heart disease, particularly admixture lesions, in which there is often excessive pulmonary blood flow and arterial saturations are often only mildly decreased.
Admixture lesions are forms of congenital heart disease in which blood from the systemic and pulmonary veins mix within the heart via a single or multiple defects (predominantly at the atrial level). When blood is completely mixed within the heart, then arterial saturation is dependent on the size of the left-to-right shunt or amount of pulmonary blood flow and whether or not there is preferential streaming of saturated or desaturated blood to the aorta. Variations in the size and location of the outflow tracts determine where the “mixed” blood is ejected. Patients with admixture lesions and unrestricted pulmonary blood flow develop pulmonary overcirculation which can result in respiratory distress/failure, difficulty feeding, failure to thrive, and potentially necrotizing enterocolitis. If left unabated, excessive pulmonary blood flow (PBF) can lead to changes in the pulmonary arterioles causing irreversible elevation of the pulmonary vascular resistance. This is of particular importance for single ventricle patients as elevated pulmonary vascular resistance can make the patient ineligible for eventual Fontan surgical palliation. To prevent these problems from developing, patients with admixture lesions and excessive PBF require interventions to limit or control the amount of flow to the lungs, often as part of a series of staged palliation surgeries for functional single ventricle anatomy and physiology.
Pulmonary Artery Banding
The current mantra in congenital heart surgery is early complete repair due to improved operative techniques as well as improved peri-operative management, resulting in excellent outcomes even with complex neonatal CHD. Therefore, the tendency is away from palliating babies to allow for growth or an older age before two ventricle repair is considered. Nevertheless, there are certain forms of CHD in which a palliative step, such as pulmonary artery banding to restrict pulmonary blood flow is necessary before complete repair is attempted. Examples include anatomic defects that continue to carry a higher risk of suboptimal early repair, such as multiple apical ventricular septal defects or patients with otherwise repairable anomalies, but have significant associated co-morbidities, such as prematurity or intracerebral hemorrhage. In these situations, a pulmonary artery band can be an effective palliative technique to control pulmonary blood flow. Also, pulmonary banding is frequently used as a first-stage procedure in the management of certain single ventricle physiologies, such as tricuspid atresia or double inlet left ventricle. The procedure can be performed via a thoracotomy or sternotomy depending on the anatomy, planned concomitant procedures, and surgeon preference. Technical aspects include creating a space between the aorta and main pulmonary artery through which a nondistensible band of prosthetic material is passed as a ring around the main pulmonary artery. The band is located between the valve and the origin of the branch pulmonary arteries. The band is then tightened to the desired effect again based on the underlying anatomy, physiology, and planned next stage. In general, the goals of a pulmonary artery band are to improve the balance of systemic to pulmonary artery circulation and to protect the distal pulmonary vasculature from unrestricted pressure and flow. Achievement of balanced flow guided by the changes in systemic oxygen saturation with tightening, and the pressure restriction is demonstrated by reduction in the pulmonary artery pressure distal to the band. In patients without a main pulmonary artery, such as truncus arteriosus, and those in which complete neonatal repair is not possible, separate banding of the left and right branch pulmonary arteries is possible. Recovery from pulmonary artery banding is usually fairly quick and patients are often easier to manage once the degree of PBF is appropriately restricted.
Procedures to Increase Mixing of Systemic and Pulmonary Venous Blood
Certain forms of cyanotic congenital heart disease are dependent on adequate intracardiac mixing of blood to maintain adequate oxygen saturations in the neonatal period. This includes conditions with transposition physiology and most admixture lesions. When inadequate mixing occurs in patients with admixture lesions, disproportionate streaming of the deoxygenated blood to the systemic circulation results in severe cyanosis. To demonstrate this, consider hypoplastic left heart syndrome (HLHS), in which the left-sided structures are not adequate to support a full cardiac output. To provide the systemic circulation with adequate quantities of oxygenated blood, there must be unrestricted flow from the left atrium to the aorta (left atrium→right atrium→right ventricle→pulmonary artery→ductus arteriosus→aorta). Thus, unrestricted atrial communication is necessary for both adequate oxygenation and maintenance of cardiac output. Furthermore, without unrestrictive atrial communication, left atrial hypertension develops because of the inability of pulmonary venous return to unload. This leads to pulmonary venous hypertension and subsequent pulmonary edema with pulmonary artery hypertension. This can be devastating for patients with single ventricle admixture lesions.
In the cyanotic condition d-transposition of the great arteries (D-TGA), the pulmonary and systemic circulations are maintained in parallel as opposed to in series. Oxygenated blood is pumped from the right ventricle to the lungs and deoxygenated blood is pumped from the left ventricle to the aorta. Unlike admixture lesions, cardiac output to the systemic circulation is normal and is not dependent on atrial level shunting. Similarly, though, if there is inadequate mixing of blood predominantly at the atrial level, the resulting physiology is not compatible with survival because of the development of severe hypoxemia. In the early newborn period, for a D-TGA patient with restrictive or intact atrial septum, the patent ductus arteriosus provides the minimal mixing necessary to maintain arterial saturations still compatible with life. However, as the ductus arteriosus constricts, the two circulations have almost no communication and severe prohibitive cyanosis results. For these patients, it is crucial to begin a prostaglandin infusion immediately after birth when the diagnosis is known or suspected. In these situations, despite maintenance of a PDA, severe cyanosis results as the ductus arteriosus alone is not an adequate source of mixing, and atrial opening is required.
In summary, all admixture lesions and conditions with transposition physiology require adequate mixing at the atrial level for survival in the neonatal period. In some cases, this involves the creation of an atrial level communication, and in other cases, enlargement of a restrictive existing communication (patent foramen ovale [PFO] or ASD) is required. In this section, we describe current approaches available to provide unrestrictive atrial level communication for both admixture lesions and conditions with transposition physiology ( Table 78.4 ).
TABLE 78.4
Congenital Heart Lesions That May Require Neonatal Atrial Septostomy
| Diagnosis | Reason for Intervention | Flow after Intervention | Special Considerations |
|---|---|---|---|
| d-Transposition of great arteries | Cyanosis | Bidirectional | |
| Tricuspid atresia | Decreased cardiac output | Right-to-left | If late—may need blade septostomy or stent placement |
| Ebstein anomaly | Decreased cardiac output | Right-to-left | |
| Total anomalous pulmonary venous return | Decreased cardiac output | Right-to-left | |
| Hypoplastic left heart syndrome | Pulmonary edema | Left-to-right | If septum is thick—may need septostomy or stent placement |
Balloon Atrial Septostomy
Balloon atrial septostomy (BAS) is the standard method for enlarging an existing atrial communication when there is inadequate mixing. The most common indication is d-transposition of the great arteries with restrictive atrial septum, which occurs in one-third of neonates with this condition. Following TGA, the second-most common indication for balloon atrial septostomy occurs in the single ventricle admixture lesion HLHS. The balloon atrial septostomy procedure has been performed for more than 50 years and remains the optimal approach in most cases because of the relative safety and efficacy when performed by experienced operators.
The standard BAS procedure can be done either in the catheterization laboratory or bedside in the neonatal intensive care unit. Procedural guidance is typically provided by fluoroscopy, echocardiography, or combination of both. Performing the procedure in the catheterization laboratory allows for additional procedures to be performed (i.e., coronary angiography) and allows easy access to additional catheterization equipment should the procedure be technically difficult. Bedside BAS under echocardiographic guidance has been shown to be a safe and more cost-effective approach in patients with d-transposition of the great arteries. The procedure can be performed via femoral venous access or by taking over the umbilical vein catheter. The BAS catheter is advanced under fluoroscopic or echocardiographic guidance until it is seen to be in the left atrium across an existing PFO/ASD ( Fig. 78.4 A , B ). The balloon is inflated in the left atrium and a quick, forceful, yet controlled, “jerk” is performed to pull the inflated balloon through the existing communication. The septum tears during this process, resulting in a larger atrial communication and hopefully unrestricted atrial shunting.
In the event of a thick septum that does not tear, repeat BAS is not advised and a different approach must be sought for the patient. If the patient is profoundly hypoxemic before and during the procedure, it is not uncommon to develop pulmonary hypertension or maintain high pulmonary vascular resistance (PVR). In this setting, pulmonary blood flow is restricted and does not allow for enough of the mixed blood to be pumped to the lung to receive oxygen. Profound cyanosis may persist despite echocardiographic evidence of an unrestrictive atrial communication. In these situations, patients should be started on inhaled nitric oxide and allowed time for their pulmonary vascular resistance to drop, which results in improved arterial saturations.
Other Atrial Septostomy Techniques
Balloon atrial septostomy may not be effective if the atrial septum is thick or completely intact. If there is an existing communication between the atria, this can be crossed and made larger with other transcatheter interventions. If no atrial communication exists, the atrial septum may be crossed using the radiofrequency wire (described in the RVOT perforation section), a radioperforation transseptal needle, or with a standard transseptal needle. Once the thick or intact septum is perforated, a guidewire can then be passed through the perforation and positioned into a left-sided pulmonary vein. At this point, there are multiple options that the operator can choose for opening the atrial septum, including static balloon septoplasty, blade atrial septostomy, and atrial septal stenting.
Static Balloon Septoplasty
Static balloon atrial septoplasty involves inflating a balloon that is stretched across the newly created perforation. As opposed to a standard BAS, a static BAS is repeated several times with progressively larger balloons. Static BAS is rarely effective for a sustained period of time if only standard angioplasty balloons are utilized. Cutting balloon septoplasty is much more effective at widening a newly created perforation and producing a more sustained outcome. Cutting balloons have four small atherotomes (microsurgical blades) attached to the longitudinal surfaces positioned 90 degrees to each other. These are designed to score the tissue against which it is in contact during inflation. The balloon is deflated and rotated/repositioned, and additional inflations are performed to create more score lines. The opening can then be further dilated with larger diameter static balloons, which tears the tissue along the multiple scored cut lines.
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