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Departments of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California; Departments of Pediatrics and Anesthesiology, Texas Children's Hospital, Houston, Texas
Address correspondence and reprint requests to Isobel A. Russell, MD, PhD, FACC, Department of Anesthesia and Perioperative Care, 521 Parnassus Avenue, San Francisco, CA 94143-0648. Address e-mail to russellb{at}anesthesia.ucsf.edu.
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Introduction |
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 Top Introduction Simple LesionsComplex LesionsReferences |
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Survival rates in CHD are influenced by many factors, including year of birth, age at diagnosis, complexity of the pathology, and whether the lesion(s) has been palliated or surgically corrected (Table 1) (1). As survival and life expectancy continue to improve, a growing number of unoperated, palliated, and "repaired" individuals require surgical interventions or other procedures related or unrelated to their heart disease. The care of these patients is becoming more frequent in all surgical settings, including tertiary care facilities, ambulatory centers, and labor and delivery suites.
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Adults with CHD may come to the attention of anesthesiologists for various indications including:
Anesthesia and surgery may carry an increased risk for adverse events during emergent or elective procedures in these patients. This is particularly the case in those with cyanosis, pulmonary hypertension, rhythm disturbances, and significant hemodynamic abnormalities. Recommendations from organizations such as the American College of Cardiology (1) and the Canadian Cardiovascular Society (2–4) suggest that these patients should be cared for by cardiac anesthesiologists who have specialized training or extensive experience in the field. However, anesthesia care providers with such advanced expertise may not always be available. The challenge in caring for these patients is further magnified by the fact that there is a heterogeneous population. Individuals may present at any time with a bewildering array of structural variations, each with specific physiologic perturbations and hemodynamic consequences, and situations that require sophisticated perioperative care. The spectrum of CHD ranges widely from relatively mild defects seen in isolation to lesions of moderate to severe complexity typically characterized by several coexistent malformations. An important objective in caring for ACHD is to diminish cardiac-related morbidity and avoid adverse perioperative events. Of utmost importance in this mission is having a basic understanding of the native anatomy, physiology, surgical strategies, and late outcome of the defect under consideration.
The primary goal of this article is to present a general overview of the most common congenital cardiovascular defects as applied to the adult age group, with a focus on anatomy, physiology, and long-term outcome (Table 2). To facilitate this review, representative images of the various congenital pathologies, as displayed by transesophageal echocardiography (TEE), accompany this contribution. The graphics are accessible as digital clips on the Web site of Anesthesia & Analgesia (www.anesthesia-analgesia.org), and we hope the clips will serve as reference material for those involved in the care of these patients. The images are labeled according to the American Society of Echocardiography/Society of Cardiovascular Anesthesiologists guidelines (5). We have made a significant effort to display most of the echocardiographic images as obtained in the population of focus, the adult patient. This imaging modality has provided significant contributions to the care of patients with structural congenital cardiovascular pathology, and we emphasize the benefits of this technology. The TEE imaging planes and information of interest for each of the lesions considered are listed in Table 3 as a guide to those who may want to become more familiar with the applications of this imaging approach to CHD. Epicardial echocardiography contributed significantly in the early experience of intraoperative imaging in patients with CHD; however, it is used primarily in patients when TEE is not feasible.
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We have divided this manuscript into a discussion of simple and complex lesions, with "complex" defined as the presence of more than one congenital malformation often requiring surgical intervention.
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Simple Lesions |
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TopIntroductionSimple LesionsComplex LesionsReferences |
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Other entities that may not be routinely considered in the classification of ASDs but may allow for interatrial shunting include a patent foramen ovale (PFO) at one end of the spectrum (25) and a confluent or common atrium at the other. Patency of the foramen ovale has been reported in as many of 25% of patients (26). In recent years, the presence of a PFO has been associated with the pathogenesis of migraine headaches (27,28). The potential for right-to-left shunting allowed by an incompetent flap of the fossa ovalis may be a risk factor in some patients for paradoxical embolization and cerebrovascular morbidity. A common atrium is characterized by complete or near-complete absence of the interatrial septum and is seen most frequently within the context of complex CHD.
A direct communication between the atrial chambers allows for pulmonary venous blood to enter the right atrium. The magnitude of interatrial shunting relates to the size of the defect, relative ventricular compliances, and pulmonary artery pressures. A clinically significant defect results in right-sided volume overload characterized by right atrial, right ventricular, and pulmonary artery dilation. The abnormally increased pulmonary blood flow may be a long-term risk factor for the development of pulmonary vascular changes in a small number of patients (5%–10%). Several factors are considered in evaluating the need for intervention. These include the magnitude of the shunt or pulmonary flow (Qp) to systemic flow (Qs) ratio (also known as Qp:Qs) and concerns regarding the potential detrimental effects of chronic right ventricular volume overload. Further factors that influence the management approach include the presence or potential for atrial arrhythmias, risks for the development of pulmonary hypertension, pulmonary vascular obstructive disease, paradoxical embolization, and right ventricular failure. It is important to recognize that physiologic changes in left ventricular compliance and aging may account for unfavorable increases in the degree of left-to-right shunting, exacerbation of symptomatology, and development of right heart failure in the adult.
Long-Term Outcome.
Primary suture or patch closure of ASDs during childhood provides excellent operative results and nearly normal long-term survival (29,30). Surgical mortality is rare for isolated secundum defects in the current medical era. However, an increased risk is recognized in older patients and those with more than mild increases in pulmonary vascular resistance. As a rule, younger patients have a better outlook after repair (29–31). However, recent data have demonstrated that ASD closure is beneficial even in patients older than 50 or 60 yr (32). Both retrospective studies and prospective clinical trials suggested improved 10-yr survival in patients older than the age of 40 yr treated surgically (95%) compared with those treated medically (84%) (30,33,34).
Atrial arrhythmias may be seen especially after the third decade of life. Late repair, after age 41 yr, does not appear to reduce the incidence of rhythm disorders (29). A management strategy that combined defect closure with arrhythmia surgery (Cox/Maze procedure) has been reported to be of benefit in these patients (35).
Closure of these defects by the transcatheter route is becoming a widespread alternative to the surgical approach (36–39). Outcomes appear to be good, with successful closure that is generally safe (40). Minimally invasive surgical techniques using a lateral thoracotomy or limited sternotomy have been developed for patients who are not candidates for interventional device closure. This surgical approach has become an attractive option for patients, with better postoperative recovery and improved cosmetic results (41,42).
The development of robotic techniques has helped reduce both incision size and overall postoperative trauma. Closure of ASDs has been performed via an endoscopic approach safely and effectively (43). In this study, quality of life outcome measures were superior in patients who received endoscopic surgery as compared with traditional sternotomy and mini-thoracotomy; however, further outcome studies are needed to evaluate the safety and efficacy of this approach.
TEE.
The identification and comprehensive characterization of ASDs by transthoracic echocardiography in the adult may be limited in some instances by poor acoustic windows. Transesophageal evaluation should be considered a complementary imaging modality in ascertaining or confirming the presence, size, and location of the defect in these patients. The mid-esophageal (ME) four-chamber and bicaval views are particularly useful in the examination of the atrial septum by two-dimensional imaging and color Doppler (Fig. 1 and Table 3) (see video clips 1–3 at www.anesthesia-analgesia.org). Additional benefits of this technology include assessment of the severity of associated atrioventricular valve regurgitation, chamber enlargement and ventricular function (transesophageal and transgastric views). Concomitant defects such as anomalous pulmonary venous drainage can also be defined by a combination of imaging planes. TEE has been shown to be of benefit during transcatheter closure by assisting in the selection of appropriate devices and monitoring during placement (Fig. 2 and Table 3) (see video clips 4 and 5 at www.anesthesia-analgesia.org) (44). Intraoperative benefits during cardiac procedures include documentation of the adequacy of the repair, exclusion of potential problems related to the intervention, and facilitation of cardiac de-airing. Obstruction to systemic or pulmonary venous flow, as well as erroneous diversion of systemic venous drainage to the left atrium, can be recognized by TEE.
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Color flow mapping contributes to the evaluation of interatrial shunting and atrioventricular valve competency. Contrast echocardiography with agitated saline can enhance the identification of small atrial level shunts, as microbubbles are readily apparent in the left atrium even when a very small number move across the defect (45,46).
Ventricular Septal Defects (VSD)
Anatomy and Physiology.
VSDs are the most common of all congenital cardiac anomalies, excluding a bicuspid aortic valve. Epidemiologic studies suggest that these defects account for nearly 30% (range, 16%–50%) of all cases (47,48). Communications at the ventricular level can be found in isolation or may be seen in the context of other structural malformations. Adults with unoperated VSDs are encountered less frequently than are those with ASDs. Large defects usually require surgical attention during childhood for symptomatology related to congestive heart failure or pulmonary hypertension. Although VSDs have a more frequent rate of spontaneous closure in children (6), small perimembranous and trabecular muscular defects may also completely close spontaneously even in adulthood (6).
Various classification schemes have been proposed for VSDs (11,49,50). The classification noted below of four major morphologic types is based on the anatomic location of the defect. However, in some cases the rims of the defect may extend beyond the margin of a particular region of the ventricular septum to another.
Defects that may be found in association with VSDs include a bicuspid aortic valve, aortic coarctation, and right ventricular outflow tract (RVOT) obstruction in the form of pulmonic valve stenosis or anomalous right ventricular muscle bundles. An interventricular communication may also be present in complex forms of CHD and in certain types of single-ventricle type arrangements.
These intracardiac communications allow for shunting at the ventricular level. The physiologic consequences of this lesion are determined by the size of the defect, amount of shunting, and relative resistances of the pulmonary and systemic vascular beds. Isolated VSDs are also classified in physiologic terms as either pressure restrictive (right ventricular pressure less than left ventricular pressure) or nonrestrictive defects (equal or near-equal ventricular pressures). If the defect is restrictive the flow across it is usually limited. This is often the case with small defects. If the defect is large and nonrestrictive the magnitude of the shunt is dependent on the ratio between the pulmonary and systemic vascular resistances. A low pulmonary vascular resistance in the context of a nonrestrictive VSD leads to a large left-to-right shunt. The excessive pulmonary blood flow in turn results in increased left ventricular end-diastolic volume.
In addition to the classification of VSDs according to their anatomic location or restrictive/nonrestrictive nature, characterization of this malformation in terms of size and likely hemodynamic significance is extremely useful as follows:
Long-Term Outcome.
Surgical closure of VSDs early in childhood results in excellent outcomes with survival into adulthood generally without sequelae (55,56). Surgical intervention in older children may be associated with reduced left ventricular function and increased left ventricular mass (57).
Small interventricular communications, although regarded as hemodynamically insignificant, may not be necessarily benign. This has led to continuing controversy regarding the need for surgical intervention. In a long-term follow-up of 188 adults with small defects, spontaneous closure occurred in 10% during adult life; however, serious complications occurred in 25% of this cohort (53). These complications included infectious endocarditis (11%), progressive aortic regurgitation (5%), and symptomatic rhythm disturbances (8.5%), with atrial fibrillation being most common (53). A number of individuals with moderate defects may remain relatively asymptomatic until adult life when gradual decompensation ensues related to ventricular dilation.
New York Heart Association functional class more than I, cardiomegaly, and an increased pulmonary artery systolic pressure (>50 mm Hg) are clinical predictors of an adverse prognosis (17). Approximately 10% of patients with nonrestrictive VSDs develop Eisenmenger's syndrome, characterized by pulmonary vascular obstructive disease and reversal in the direction of the ventricular level shunt (6). These patients can survive into adulthood but typically have an overall decreased survival rate.
The initial description of the clinical features of what today is known as Eisenmenger's syndrome was made in 1897 (58). Several years later the term "Eisenmenger's complex" was formally coined to include pulmonary hypertension at systemic levels related to increased pulmonary vascular resistance, with reversed or bidirectional shunting through a large VSD (59). This syndrome now describes the physiology associated with obliterative pulmonary vascular changes and cyanosis related to a reversal in the direction of an intracardiac or arterial level shunt.
Morbidity in these patients relates to problems associated with chronic cyanosis and erythrocytosis, such as thromboembolic events, cerebrovascular complications, and the hyperviscosity syndrome. Other complications include hemoptysis, gout, cholelithiasis, hypertrophic osteoarthropathy, and decreased renal function.
The long-term prognosis for patients with this syndrome is better than in those with other causes of pulmonary vascular pathology, such as primary pulmonary hypertension (60). However, life expectancy is significantly altered, with a reported survival rate of 80% at 10 yr, 77% at 15 yr, and 42% at 25 yr (61). Variables associated with poor outcomes include syncope, increased right ventricular end-diastolic pressure, and significant hypoxemia (systemic arterial oxygen saturation of <85%) (61). Most patients succumb suddenly, probably from ventricular arrhythmias. Patients with Eisenmenger's have undergone combined heart and lung transplantation (62) and lung transplantation alone has evolved as an alternate therapy (63).
Surgical closure of VSDs is recommended if the magnitude of the increase in pulmonary vascular resistance is not prohibitive. However, if the ratio of the pulmonary to systemic vascular resistance exceeds 0.7, the risk associated with surgical intervention is significant. In a series of adult patients with VSDs, no postoperative problems were experienced if the resting pulmonary vascular resistance was 
7.9 U/m2 (Woods units) (64). If postoperative pulmonary hypertension persists, the prognosis is unfavorable, with right ventricular failure occurring commonly (65,66). In patients with defects associated with aortic regurgitation, late results after surgical closure of the defect and concomitant aortic valvuloplasty are generally good. A survival rate of 96% at 10 yr has been reported in young patients, with freedom from valvuloplasty failure and freedom from reoperation documented to be 76% and 85%, respectively, at 10 yr (67).
Transcatheter closure has been increasing in popularity (68) for both postoperative residual and muscular VSDs (69–71) with excellent closure rates and infrequent mortality.
TEE.
The role of TEE in the evaluation of patients with VSDs has been well described (Table 3) (72,73). Transesophageal examination allows for definition of the location and size of the defect and determination of chamber sizes and vessel dimensions, aids in the detection of associated anomalies, and provides for identification of ventricular septal aneurysms if present, in addition to the assessment of the aortic valve for herniation and/or regurgitation (74). Views that allow for a comprehensive examination of the ventricular septum include the ME four-chamber view (with sweeps that span from the anterior [outlet] to the posterior [inlet] aspects) and the transgastric (TG) mid short axis (SAX) view (Figs. 3 and 4 and Table 3) (see video clips 6–9 at www.anesthesia-analgesia.org). Doppler color flow imaging allows for determination of the direction and magnitude of the ventricular shunt and permits identification and quantitation of associated aortic regurgitation. Pulsed and continuous wave Doppler can be used to determine the peak flow velocity across the VSD and to provide an estimate of RVSP and pulmonary artery systolic pressure. In the presence of restriction, the peak velocity across the VSD is high, consistent with a relatively high systolic pressure gradient across the ventricular chambers. In the absence of pulmonary outflow tract obstruction the peak velocity across the VSD as determined by spectral Doppler can be used to predict RVSP according to the modified Bernoulli equation as follows (75):
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In the presence of tricuspid regurgitation (TR), the RVSP can also be estimated:
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During the surgical repair of VSDs or transcatheter closure, TEE is able to provide guidance and detect residual shunts by two-dimensional, color Doppler, and contrast imaging (68,76–78). Further benefits include evaluation of coexistent lesions, outflow obstruction, valvular regurgitation and ventricular function.
Atrioventricular Septal Defects (AVSD)
Anatomy and Physiology.
AVSDs, or canal defects, are characterized by abnormal endocardial cushion development, resulting in deficiency of the atrioventricular septum and altered formation of the atrioventricular valves (79,80). In the complete form of this malformation there is an inferior interatrial communication or ostium primum defect, an interventricular communication at the superior aspect of the inlet or posterior muscular septum and a common atrioventricular valve. In the partial form, an ostium primum ASD is accompanied by a cleft or commissure in the left-sided atrioventricular valve and two functionally distinct atrioventricular valvular orifices are generally identified. The prevalence of these defects is frequent among patients with Down syndrome.
Complete AVSDs are typically associated with nonrestrictive intracardiac shunting, excessive pulmonary blood flow, and excessive systemic pressures in the right ventricle and pulmonary artery. Without intervention this may result in early pulmonary vascular changes and the development of fixed pulmonary vascular obstructive disease. The severity of atrioventricular valve regurgitation also influences the clinical presentation. Partial AVSDs are less likely to be associated with pulmonary overcirculation severe enough to cause significant heart failure symptoms.
Long-Term Outcome.
Most adults with the complete form of this defect have undergone complete repair in childhood. In some patients, initial palliation may have consisted of pulmonary artery banding to restrict pulmonary blood flow, followed by subsequent definite repair. Over the last several decades, the surgical approach has evolved from a two-stage intervention to a single surgical strategy of primary repair in infancy (81). The long-term outlook after repair of AVSDs is good. In a few patients, uncorrected defects have resulted in Eisenmenger's physiology, rendering them inoperable candidates. This is associated with significant late morbidity and early death (61,82,83).
Although definitive repair is usually accomplished during childhood, various publications have documented the results of surgical intervention in adults with partial forms of defects. Patients older than 40 yr of age may undergo reparative surgery with low operative risk (84); however, they may require long-term surveillance because late mitral valve dysfunction may occur. Among 50 patients who underwent surgery for partial AVSDs (mean age, 36.6 yr; 39 of them being intervened for the first time for a substantial shunt), a low operative risk was reported and excellent long-term results were achieved (85).
Complications after repair of an AVSD include residual intracardiac shunting, left atrioventricular valve stenosis or regurgitation, and subaortic obstruction.
TEE.
In patients with AVSDs, TEE is useful in confirming the anatomy and defining the type and extension of the septal defects (Table 3) (86). Two- and three-dimensional TEE imaging has been shown to be of benefit preoperatively, not only during the initial repair but also when reinterventions have been necessary (87,88). The deficiency in the atrial and ventricular septa and the large common atrioventricular valve can be readily identified in the ME four-chamber view (Fig. 5 and Table 3) (see video clip 10 at www.anesthesia-analgesia.org). In the complete form of the defect, characterization of the "bridging leaflets," which span the common orifice, assists in the classification of these defects into types A, B, or C as proposed by Rastelli et al. (79) according to the anterosuperior bridging leaflet morphology. Other information of interest that is well outlined by TEE includes atrioventricular valve competency, associated ventricular outflow obstruction, and noninvasive assessment of pulmonary artery pressures. In the postoperative patient, TEE can assist in the determination of residual defects, status of the atrioventricular valves, and evaluation of ventricular function.
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Pulmonic Valve Stenosis
Anatomy and Physiology.
Although isolated valvular pulmonic stenosis (PS), also known as "pulmonary valve stenosis," is congenital in origin in most cases, this pathology can be progressive. This lesion accounts for 7%–10% of patients with CHD. Findings typically include systolic valvular doming, various degrees of leaflet tethering and thickening, and commissural fusion resulting in the formation of peripheral raphes and narrowing of the valve. In the uncomplicated or pure form of PS the ventricular septum is intact. An interatrial communication in the form of a PFO or secundum ASD is often identified in this setting. In a few patients (approximately 20% of all cases), a variant characterized by valvular dysplasia is recognized (89). This is associated with marked valvular thickening or mucoid degeneration. Other less common forms of right ventricular outflow tract obstruction include infundibular or subpulmonary obstruction, supravalvular stenosis, or double-chambered right ventricle (characterized by the presence of anomalous muscle bundles within the trabecular component of the right ventricle).
The magnitude of right ventricular outflow tract obstruction in patients with PS is directly related to the degree of valvular narrowing. The obstruction to pulmonary outflow imposes an afterload burden on the right ventricle, resulting in right ventricular hypertrophy and decreased diastolic compliance. This lesion is relatively well tolerated over time; however, severe right ventricular hypertrophy with increased systolic compression may lead to compromised intramural coronary flow. The increased right ventricular myocardial oxygen demand may result in subendocardial ischemia.
Long-Term Outcome.
Severe PS is unusual in adults. Generally, outcomes are excellent in patients with this pathology and morbidity is relatively infrequent. Right ventricular failure rarely occurs. Historically, surgical valvotomy has been extremely successful for long-term relief of the outflow obstruction. A natural history study of surgically treated patients (peak systolic gradient exceeding 80 mm Hg) demonstrated an excellent 25-yr survival of 95%, equivalent to that of the normal population (90). In the adult, moderate to severe PS that would likely benefit from intervention is generally defined by a peak transvalvular Doppler gradient more than 60 mm Hg, although intervention may be recommended for lesser degrees of stenosis in the presence of symptoms. In most patients, percutaneous balloon valvuloplasty is highly effective and considered the treatment of choice, replacing surgical valvotomy in most cases (91–94). Dysplastic valves have a less favorable response to catheter-based interventions. Considerations for reintervention include residual right ventricular outflow tract obstruction and progressive pulmonary regurgitation.
TEE.
Two-dimensional imaging in the ME aortic valve (AV) SAX and ME right ventricle (RV) inflow-outflow views demonstrates the stenotic, doming valve leaflets in PS (Table 3) (95). The valvular orifice can range from a pinhole to several millimeters in diameter but is rarely critical in the adult. Pulmonary regurgitation resulting from prior interventions may also be identified and qualitatively assessed in these views. On occasion, visualization of the pulmonic valve can be challenging by TEE because of its distant anterior location relative to the probe position in the esophagus. Transgastric imaging may allow for further anatomic definition. An accurate measurement of the pressure gradient across the right ventricular outflow tract is feasible with spectral (continuous wave) Doppler interrogation, usually from the ME ascending aortic SAX and deep TG views. An interatrial communication may be also identified by two-dimensional, color Doppler, or contrast imaging. A combination of ME and TG views is useful for assessing the severity of right ventricular hypertrophy and systolic function. Diastolic abnormalities associated with reduced ventricular compliance may be present in these patients, as documented by spectral Doppler interrogation (96).
Left Ventricular Outflow Tract Obstruction
Anatomy and Physiology.
Obstruction to left ventricular outflow can occur at the level of the aortic valve, above the valve (supravalvular), or below the valve (subvalvular). This may take place in isolation or as part of complex CHD.
The bicuspid aortic valve is the most common valvular anomaly and variant of congenital aortic valve stenosis. This is also reported to be the most frequent of all congenital cardiac malformations, occurring in approximately 2% of the general population. The pathology is the result of commissural fusion leading to the finding of a raphe or "false" commissure (Fig. 6 and Table 3) (see video clip 11 at www.anesthesia-analgesia.org). Although this abnormality does not necessarily imply valvular stenosis, it may be associated with the development of progressive obstruction or regurgitation. A bicuspid aortic valve may be found in asymptomatic individuals, either within the context of associated left ventricular obstructive lesions or as part of the spectrum of left ventricular hypoplasia. The prevalence of associated defects is relatively frequent (up to 20%) and often includes patent ductus arteriosus (PDA), aortic coarctation, VSD, and ascending aortopathy. Congenital valvular stenosis has a male predominance and accounts for approximately 5% of CHD.
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Patients with severely malformed, stenotic valves may require intervention during childhood. Even with a less restricted orifice, the disturbed flow through the valve causes progressive thickening and calcification and may eventually result in severe stenosis and varying degrees of valvular regurgitation that become manifest later in life.
In supravalvular aortic stenosis, the narrowing is typically at the sinotubular junction (Fig. 7, left, and Table 3) (see video clip 12 at www.anesthesia-analgesia.org). The coronary arteries arise proximal to the area of obstruction and are subjected to increased systolic pressures equal to that of the left ventricle. This may lead to coronary artery dilation and accelerated atherosclerosis. The arteriopathy found in these patients may also involve the origin of the coronary arteries or other systemic and pulmonary vessels. Diffuse narrowing of the abdominal aorta may occur in association with renal artery stenosis. This malformation is considered to be the result of a mutation or alteration of the elastin gene and may occur as part of Williams syndrome (characterized by elfin facies, mental retardation, idiopathic hypercalcemia, and other features).
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Subvalvular stenosis may take a variety of forms, including a discrete fibromuscular ridge or membrane, a complex, "tunnel-like" obstruction, or hypertrophy of the interventricular septum as seen in hypertrophic cardiomyopathy (Fig. 7, right, and Table 3) (see video clip 13 at www.anesthesia-analgesia.org). Discrete disease accounts for nearly 10% of cases of aortic outflow obstruction. The shelf that frequently encircles the outflow tract is considered to be an acquired pathology as it is unusual in infancy. A systolic jet develops that traumatizes the valve leaflets and may lead to aortic regurgitation. Less common forms of subaortic obstruction, such as complex tunnel-like narrowing, are observed in association with other malformations that include aortic valve stenosis, annular hypoplasia, and posterior malalignment of the ventricular septum (as may be the case in patients with aortic arch interruption). The association of left ventricular obstructive lesions such as a bicuspid aortic valve, subaortic stenosis, aortic coarctation, and mitral valve abnormalities that result in ventricular inflow obstruction (parachute mitral valve, supravalvular mitral ring) is known as Shone's complex.
A common denominator among lesions that result in impedance to left ventricular ejection includes a pressure gradient across the obstruction and increase of left ventricular systolic pressure. This results in increased myocardial force and left ventricular wall stress. With chronic obstruction, the hypertrophied myocardium may be at risk for the development of subendocardial ischemia as a consequence of an imbalance in the ratio of myocardial oxygen supply and demand. Factors such as increasing left ventricular afterload, inadequate hypertrophic remodeling, and decreased myocardial systolic or diastolic performance may compromise stroke volume and contribute to cardiac dysfunction and heart failure in this setting.
Long-Term Outcome.
Patients with a bicuspid aortic valve may remain asymptomatic for many years but are at risk for developing endocarditis, aortic stenosis, or regurgitation. Approximately one fourth of patients requiring surgical intervention during childhood undergo reoperation for recurrent stenosis or progressive regurgitation within the following 25 yr (97). With medical treatment, approximately one third of children with systolic gradients less than 50 mm Hg and approximately 80% of those with gradients 50 to 79 mm Hg need surgery within 25 yr (97). With symptomatic, hemodynamically significant valvular aortic stenosis (i.e., an aortic valve area <0.8 cm2) and a flexible noncalcified valve, balloon valvuloplasty may have therapeutic success similar to that of open valvotomy, even in young adults (98). In the adolescent and adult, a variety of surgical approaches has been advocated for management of valvular obstruction. These include valve repair/replacement with mechanical or bioprosthetic devices. The Ross procedure might be favored in young patients because of growth potential of the pulmonary autograft (neoaorta) (99–101). Further advantages of this approach are that it obviates the need for anticoagulation and its concomitant potential morbidity. Short-term and midterm results of the Ross procedure are encouraging, with mortality rates near 2% (102). Pulmonary homograft failure (need for reoperation), dysfunction (mean gradient >40 mm Hg or more than moderate), and RV failure can occur, as can aortic dilation with subsequent regurgitation (103,104).
The management of discrete subaortic stenosis remains a challenge and the timing of surgery is controversial because of conflicting reports on mid- and long-term survival (105). Data suggest that surgical resection of the subaortic membrane before the development of a significant gradient (>40 mm Hg) may prevent recurrence, reoperation, and secondary progressive aortic valve disease.
TEE.
Transesophageal imaging and Doppler interrogation is particularly helpful in the assessment of aortic valve morphology, measurement of annular size and valve area, identification of post-stenotic dilation of the ascending aorta, delineation of valvular, subvalvular, or supravalvular pathology, characterization of the degree of ventricular hypertrophy and myocardial function, and estimation of the pressure gradient across the obstruction (Figs. 6 and 7) (see video clips 11–13 at www.anesthesia-analgesia.org). (106–111). Continuous-wave Doppler interrogation across the area of obstruction from the TG long axis (LAX) and deep TG LAX views provides for optimal alignment of the Doppler angle of incidence with the left ventricular outflow and determination of accurate gradients (112).
Evaluation of the repair, including function of aortic mechanical or bioprosthesis, paravalvular regurgitation, and pulmonary autograft, is facilitated by TEE (113–115). The valuable contribution of TEE in adult patients with suspected aortic valve vegetations and root abscesses has been documented (116). The use of TEE during catheter interventions in aortic valve disease has also been described (117).
Patent Ductus Arteriosus (PDA)
Anatomy and Physiology.
The ductus arteriosus is a vascular structure that connects the proximal descending aorta to the pulmonary trunk. This communication is an essential component of the fetal circulation, allowing for right ventricular output into the descending aorta in the context of the typically elevated pulmonary vascular resistance. Persistent PDA accounts for approximately 10% of cases of CHD. This lesion may be found in isolation or in association with other forms of heart disease (Fig. 8 and Table 3) (see video clip 14 at www.anesthesia-analgesia.org).
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The magnitude of left-to-right shunting in patients with this defect depends on the size of the communication and the pulmonary vascular resistance in a manner similar to that of a VSD. The physiologic effects are those of increased pulmonary blood flow and left ventricular volume overload.
Long-Term Outcome.
Patients with an inaudible (silent) or small PDA usually have normal life expectancy. Survival to adulthood may be attributed to a relatively small left-to-right shunt and absence of pulmonary vascular changes. Most adults with hemodynamically significant communications eventually develop symptomatology characterized by dyspnea, atrial rhythm disturbances, and exercise intolerance (118). Patients with this pathology can develop moderate-to-severe pulmonary hypertension. The ventricular volume overload can result in congestive heart failure. Similar to the case of a large interventricular communication, the longstanding high pressure, high flow state can lead to increased pulmonary arteriolar resistance and Eisenmenger's physiology. There is a cumulative risk of endocarditis in patients with PDA, particularly if the ductus is restrictive (119).
Traditionally, surgical closure of even small ductuses has been performed by ligation or division of the abnormal communication with the goal of preventing infective endarteritis or endocarditis and the chronic effects of ventricular volume overload. Some centers have described the use of a video-assisted thoracoscopic approach and robotically assisted ductal closure with good results (120–122). The presence of calcification in the region of the ductus in older individuals has been associated with a higher risk of complications. Percutaneous catheter closure using coils or intravascular occlusion devices is feasible in some patients, with an approximately 95% success rate at intermediate follow-up (123,124); data on long-term follow-up are limited. Indications for intervention include symptomatology related to the large left-to-right shunt, particularly in the context of increased pulmonary artery pressures, or symptoms consistent with significant ventricular volume overload. Test balloon occlusion has been advocated before definitive intervention in adult patients with increased pulmonary artery pressures or vascular resistance.
TEE.
Assessment of ductal patency is somewhat difficult by two-dimensional transesophageal imaging alone. However, the diagnosis is facilitated by spectral and color Doppler interrogation of the pulmonary artery and descending aorta. Color flow mapping in the region of the distal main pulmonary artery in the presence of a PDA demonstrates continuous, high-velocity "aliased" flow near the origin of the left pulmonary artery (Fig. 8) (see video clip 14 at www.anesthesia-analgesia.org) (125–127). Spectral Doppler interrogation documents the flow to extend into diastole. A PDA may also be suggested by the presence of diastolic flow reversal in the thoracic aorta. Contrast injection of agitated saline into a central vein while imaging the descending aorta by TEE may demonstrate microcavitations distal to the level of the left subclavian artery consistent with ductal level right-to left shunting (128). The utility of TEE has also been described in the assessment of residual ductal shunting during catheter interventions and surgical closure (121,129–132).
Estimations of pulmonary artery pressures can be accomplished by examining the regurgitant tricuspid or pulmonary velocity profiles or the flow across the ductus (133). The pulmonary artery systolic pressure (PASP) can be calculated as follows:
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where v = peak diastolic flow velocity across ductus.
Coarctation of the Aorta
Anatomy and Physiology.
In this anomaly there is narrowing of the aortic lumen in the thoracic region immediately distal to the origin of the left subclavian artery (Fig. 9 and Table 3) (see video clip 15 at www.anesthesia-analgesia.org). In most cases, this pathology is congenital. This defect accounts for 5%–8% of all congenital cardiovascular pathology.
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The constriction in aortic coarctation may take the form of a discrete infolding-like posterior shelf or a diffuse hourglass narrowing of the distal arch in the region of the ligamentum arteriosus. A long, narrowed aortic segment is often associated with hypoplasia of the transverse arch and aortic isthmus, in which case other structural cardiac malformations may also be present. Associated defects include a bicuspid aortic valve, VSD, mitral valve abnormalities, or various other types of left-sided obstructive lesions (6). This is not an uncommon presentation in early infancy.
The hemodynamic repercussions of this lesion relate to the obstruction to systemic blood flow. Arterial hypertension is usually present proximal to the aortic obstruction. Collateral circulation is typically seen with longstanding pathology.
Long-Term Outcome.
The presence of symptoms associated with severe arch obstruction or concomitant cardiovascular defects leads to intervention in early infancy and childhood. Adult patients with untreated disease typically have a mild degree of obstruction. More than 80% of untreated patients do not survive beyond the age of 50 yr (134). Morbidity and mortality in the adult population with aortic coarctation are primarily related to complications from associated systemic hypertension: ischemic cerebrovascular disease, intracranial hemorrhage, myocardial infarction, congestive heart failure, or aortic rupture (134). Surgical intervention has significantly improved survival, but morbidity and mortality is still more frequent compared with healthy adults because of persistent postoperative systemic hypertension, accelerated coronary artery disease, and aortic dissection (135).
Intervention is usually undertaken when the coarctation is severe enough to cause proximal hypertension and a gradient across the obstruction that exceeds 25 to 30 mm Hg. Catheter techniques that include balloon angioplasty, with and without stent implantation, have been shown to be effective in relieving the obstruction and normalizing arterial blood pressure in some patients (136). Aortic aneurysms can occur around the area of coarctation or elsewhere in the aorta after angioplasty in 7%–13% of adults (137). Stenting does not eliminate the risk of aneurysm, aortic rupture, or dissection, but it is unclear whether these risks are less with stent placement than with balloon dilation alone (138). Various surgical techniques have been proposed for the management of this lesion, each with specific potential advantages and disadvantages. Repair at an early age is advocated in light of the low surgical risk in the younger age group and to minimize late morbidity. Surgery in adulthood can be complicated by the presence of multiple collateral vessels (suggested on chest radiograph by rib notching) and degenerative atheromatous changes at the site of the coarctation. This accounts for more frequent intraoperative mortality in adult patients.
TEE.
It may be difficult to visualize the actual site of coarctation by two-dimensional transesophageal imaging (Fig. 9) (see video clip 15 at anesthesia-analgesia.org). However, color Doppler interrogation of the descending aorta may facilitate this assessment by identifying flow acceleration, turbulent jets, or a pressure gradient, which continues into diastole (139). An associated bicuspid aortic valve may also be recognized by TEE (140). Angiography, magnetic resonance imaging, or another imaging modality is usually needed to define the site and extent of the aortic narrowing (141).
Left Superior Vena Cava (LSVC)
Anatomy and Physiology.
A persistent LSVC is a form of anomalous systemic venous drainage caused by persistence of the embryonic left anterior cardinal vein. Autopsy studies have shown the frequency of LSVC to be 0.3% (142). It occurs in 4.4% of patients with CHD, most frequently in those with septal defects. Usually, the LSVC enters the heart through the orifice of an enlarged coronary sinus (Fig. 10 and Table 3) (see video clips 16 and 17 at www.anesthesia-analgesia.org). Thus, when an enlarged coronary sinus is seen, a LSVC should be suspected. Other causes of a dilated coronary sinus include TR with a jet directed at the mouth of the coronary sinus, right atrial hypertension, and, rarely, stenosis of the ostium of the coronary sinus.
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In most cases of a persistent LSVC, a right superior cava is present and may or may not communicate with the left (via an innominate or bridging vein), but absence of the right superior cava can occur (though rarely) (142). The confirmation of an LSVC to coronary sinus is important because of the frequent associated malformations (143–145) and is also relevant for patients who may be candidates for single-ventricle palliation involving cavopulmonary connections (146). In addition, the presence of a persistent superior vena cava may have several implications as follows: it may confound the insertion of a pulmonary artery catheter or may interfere with the administration of retrograde cardioplegia (147).
Long-Term Outcome.
In most cases, patients with an LSVC are asymptomatic but it is important to identify the condition given its association with other cardiac lesions.
TEE.
This anomaly is suspected in the presence of a dilated coronary sinus identified in the four-chamber view as a large circular structure adjacent to the lateral annulus of the mitral valve (Fig. 10) (see video clip 16 at www.anesthesia-analgesia.org) or seen as a posterior vessel entering the right atrium (Fig. 10) (see video clip 17, left, at www.anesthesia-analgesia.org). A saline contrast injection into a left arm IV catheter can be used to confirm the presence of a LSVC (Fig. 10 and Table 3) (see video clip 17, right, at www.anesthesia-analgesia.org).
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Complex Lesions |
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TopIntroductionSimple LesionsComplex LesionsReferences |
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Hypertrophy of the right ventricular myocardium is a compensatory response to the ventricular pressure load. The combination of the large, nonrestrictive VSD and the right ventricular obstruction results in an increased right ventricular systolic pressure similar to the systemic arterial pressure. Increasing degrees of right ventricular outflow tract obstruction or decreases in systemic vascular resistance are associated with right-to-left intracardiac shunting, arterial desaturation, and clinical cyanosis.
A number of tetralogy variants are recognized. These range from the "pink form" of tetralogy at one end of the spectrum to complex defects such as pulmonary atresia with VSD and absent pulmonary valve syndrome. "Pink" tetralogy refers to a clinical setting where cyanosis is minimal as a result of a mild degree of right ventricular obstruction. In severe forms of tetralogy the main pulmonary trunk or its branches may be significantly hypoplastic or even absent, as is the case in pulmonary atresia. The pulmonary blood flow in this setting is derived from aortopulmonary collateral vessels.
Several associated cardiovascular anomalies have been described in patients with TOF. These include an interatrial communication in the form of a PFO or ASD (so-called "pentalogy of Fallot," in 10% of cases), additional VSDs, right aortic arch (in 25% of patients), aberrant origin and course of a subclavian artery, persistent connection between the LSVC and coronary sinus, coronary artery abnormalities, discontinuous pulmonary arteries, and AVSD.
Rarely, in adults with a perimembranous VSD, acquired hypertrophy of right ventricular muscle bundles may result in pathophysiology similar to that of TOF.
Long-Term Outcome.
Survival beyond childhood is unlikely in the majority of unoperated patients with TOF. Most patients with this anomaly have had palliative operations or corrective surgery by the time they reach young adulthood. Before surgical intervention, most patients died in the second decade of life. Occasionally, an individual reaches the third decade of life without surgery. Older age of repair is associated with an increased risk of sudden death and atrial tachyarrhythmia (148). Rarely, patients present with only palliative procedures aimed at increasing pulmonary blood flow.
Although a successful operation, definitive repair of TOF may be associated with significant postoperative residua. In the past, corrective surgery was often accomplished by a right ventriculotomy that facilitated resection of the subpulmonary obstruction and closure of the VSD. One approach to address the right ventricular obstruction was placement of a large patch that encompassed the subpulmonic region, valve annulus, and supravalvular region. This so called "transannular patch" was effective in relieving the obstruction; however, it invariably resulted in pulmonary regurgitation, which is progressive over time. Conditions that may require either catheter or surgical intervention in the postoperative patient include residual intracardiac shunting associated with hemodynamic burden, obstruction along the right ventricular outflow tract or pulmonary bed, and pulmonary regurgitation of significant severity. Aortic root dilation can eventually result in regurgitation and a need for surgical intervention. In the early and intermediate follow-up period, important residual right ventricular outflow tract obstruction appears to be the major source of morbidity and mortality. However, in the late follow-up period, pulmonary regurgitation with eventual right ventricular failure owing to volume overload and ventricular arrhythmias may lead to disability and even death. Survival in the postoperative patient with TOF is approximately 90% at approximately 30 yr after surgery (149). In a large series of 163 patients who had undergone complete repair of TOF (149), the 32-yr actuarial survival was 86% compared with a rate of 96% in a matched control population. Most adults with this lesion come to surgery for correction of significant hemodynamic sequelae, especially pulmonary outflow pathology and, less frequently, for residual intracardiac shunts. In adults with repaired TOF and chronic pulmonary regurgitation, right ventricular dilation has been found to correlate with an increased incidence of sudden death (150). In a retrospective review of patients who had pulmonic valve replacement to address regurgitation after repair of TOF, it was noted that recovery of right ventricular systolic function may be compromised. Thus, it is recommended that intervention be considered before ventricular function deteriorates. The performance of a palliative Blalock-Taussig shunt before definitive repair, unlike the creation of other aorto-pulmonary artery connections, was not associated with reduced long-term survival. Independent negative predictors of long-term survival included older age at operation and a higher ratio of right-to-left ventricular systolic pressure after surgery. Rarely, adults with TOF present who have only undergone a palliative procedure designed to increase pulmonary blood flow (e.g., Blalock-Taussig or other systemic to pulmonary shunts).
In recognition of the long-term morbidity associated with significant pulmonary regurgitation, the surgical strategy for this defect has undergone appraisal and modification over the years. The current approach involves avoidance of an extensive ventriculotomy, if feasible, limiting the infundibular incision and size of the transannular patch. Palliation versus definitive surgery in early infancy is an issue of continuing debate.
TEE.
TEE is useful for definition of the pathology, which is best seen in the ME AV LAX (Fig. 11 and Table 3) (see video clips 18–20 at www.anesthesia-analgesia.org). In patients with unrepaired TOF, TEE demonstrates the nature and severity of the right ventricular outflow tract obstruction. The large VSD is readily identified as is the overriding relationship of the aorta to the ventricular septum. Color-flow Doppler interrogation is helpful in ascertaining the direction of shunting across the ventricular septum and in the exclusion of additional defects. The right ventricular outflow tract gradient can be quantitated by spectral Doppler on interrogation from the ME RV inflow-outflow views and main pulmonary artery, as the probe is withdrawn slightly from the ME AV SAX view (5). Transgastric imaging adds to the anatomic and hemodynamic evaluation of the defects. The contribution of TEE during the surgical repair of TOF and its reliability in assessing the presence and severity of residual abnormalities has been documented (151,152).
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d-Transposition of the Great Arteries (d-TGA)
Anatomy and Physiology.
In d-TGA, the aorta arises from the anatomic right ventricle and the pulmonary artery from the anatomic left ventricle. The discordant ventriculoarterial connection results in an abnormal relation between great arteries. The most common morphologic arrangement is characterized by an aorta oriented in an anterior and rightward position with respect to the pulmonary artery. This lesion accounts for 5%–7% of congenital cardiovascular malformations and is the most common form of cyanotic heart disease identified in the neonate. Associated anomalies include a VSD (present in 20% of patients), left ventricular outflow tract obstruction, and coronary artery anomalies.
In d-TGA the systemic and pulmonary circulations function in parallel, rather than in series, resulting in cyanosis. Without mixing at the atrial, ventricular, or ductal level,
