**3. Preoperative evaluation of the Fontan patient**

### **3.1 Perioperative risk stratification**

Anesthesiologists outside of referral pediatric cardiovascular hospitals should be familiar with the anatomy, physiology, long-term manifestations and unique perioperative management of patients with Fontan palliation, and in the preoperative anesthesia consultation it is of paramount importance to define if this group of patients have an increased perioperative risk.

Faraoni et al. investigated the post-operative outcomes in children with and without CHD undergoing noncardiac surgery [1]. This study was performed using data from the 2012 pediatric database of the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP Pediatric). They included elective versus emergent surgery, and different surgical types (i.e., thoracic, neurological, orthopedic, general pediatric (including ear, nose, and throat), plastics and urogynecology).

Children with CHD were classified into three groups: minor, major and severe CHD, as defined in the ACS NSQIP database, based on residual lesion burden and cardiovascular functional status (**Table 1**).

This authors evaluated in the cohort of patients if the presence of major or severe CHD is associated with an increased risk of anesthesia and surgery. Of the 51,008 children included in the database, 4520 children with CHD underwent noncardiac surgery. After propensity score matching, they included 2805 children with minor CHD, 1272 with major CHD, and 417 with severe CHD. The overall mortality was significantly higher in children presenting moderate (3.9%) and severe (8.2%) CHD compared with controls (1.2% and 1.7% respectively). No statistical difference was observed in children with minor CHD (1.5%) and their controls (1%).

The conclusions of the authors are children with major and severe CHD undergoing noncardiac surgery have an increased risk of mortality, and a higher incidence of post-operative reintubation compared with matched controls undergoing comparable procedures. In the study, overall mortality in children with CHD was 2.8% compared with 1.2% in children without CHD, corresponding to a 2.3-fold higher mortality rate in children with CHD. In conclusion, children with major or

**113**

palliation [13].

team may be helpful [14].

*Physiopathological Approach of the Fontan Patient for Noncardiac Surgery for the Anesthesiologist*

• Cardiac condition with or without medication and maintenance (e.g., atrial septal defect, small-to-

• Repair of congenital heart defect with residual hemodynamic abnormality with or without medications (e.g., Tetralogy of Fallot with wide open pulmonary insufficiency, HLHS including stage 1

• Repair of congenital heart defect with normal cardiovascular function and no medication

severe CHD who undergo noncardiac surgery have an increased risk of mortality with a higher incidence of life-threatening postoperative outcomes compared with

Then Faraoni et al., developed a validation of a risk stratification score for children with CHD undergoing noncardiac surgery [13]. The objective of this study was to identify the predictors for in-hospital mortality, and to develop a risk stratification score that could be used to help decision making and the development of perioperative management guidelines. This study was performed using data from the 2012, 2013, and 2014 pediatric databases of the ACS NSQIP and included all children with major or severe CHD as previously defined. They were able to identify eight predictors for in-hospital mortality in children with major and severe CHD undergoing noncardiac surgery: four were preoperative markers of critical illness (inotropic support, mechanical ventilation, preoperative cardiopulmonary resuscitation (CPR) and acute or chronic kidney injury), the type of lesion (e.g., single ventricle physiology (SVP)) and the functional severity of heart disease (e.g., severe CHD). All of them were excellent predictors of in-hospital mortality (**Table 2**). Children with SVP were identified to be at high risk for perioperative complications and at increased risk of in-hospital mortality regardless of their functional status. Although ACS NSQIP Pediatric database allows identification of patients with SVP, does not provide accurate information on their specific stage of

The 2018 ACC/AHA guidelines for the management of adults with CHD (ACHD) stated that patients with ACHD may have greater operative risk than patients without ACHD. The guidelines recommend optimization before and close surveillance after invasive procedures regardless of the complexity of the anatomic defect or type of procedure. In patients with ACHD, especially those with complex disease (ACHD AP classification II and III) and/or whose disease has progressed (stages B, C, D), noncardiac surgical and interventional procedures should be performed in a hospital with or in consultation with experts in ACHD when possible. Because the inability to access resources or urgent conditions may preclude transfer or timely consultation, collaboration with members of the multidisciplinary ACHD

*DOI: http://dx.doi.org/10.5772/intechopen.93388*

• Uncorrected cyanotic heart disease

• Listed for heart transplant

moderate ventricular septal defect with no symptoms)

• Patients with any documented pulmonary hypertension • Patients with ventricular dysfunction requiring medication

*CHD, congenital heart disease; HLHS, hypoplastic left-heart syndrome.*

**Minor CHD:**

**Major CHD:**

**Table 1.**

repair) **Severe CHD:**

children without CHD [1].

*Groups of children with CHD.*


*Groups of children with CHD.*

*Advances in Complex Valvular Disease*

obstruction by external compression [2].

delivery even if the saturation is diminished.

symptom-free survival for as long as possible.

patients have an increased perioperative risk.

cardiovascular functional status (**Table 1**).

**3.1 Perioperative risk stratification**

**3. Preoperative evaluation of the Fontan patient**

of large vessels or microvessels, turbulence and flow collision, flow mismatch and

The strategy to manage a failing Fontan starts by determining modifiable conditions and intervene if it is deem necessary. The first step is imaging, using transthoracic echocardiography (TTE) and cardiac magnetic resonance (CMR) to obtain a full image of the Fontan anatomy. Assessment of atrioventricular valve regurgitation could be difficult therefore the use of transesophageal echocardiography (TEE) is needed sometimes. Catheter-based intervention is used if obstruction

The goal of the management of the patient with Fontan physiology is to preserve

Anesthesiologists outside of referral pediatric cardiovascular hospitals should be familiar with the anatomy, physiology, long-term manifestations and unique perioperative management of patients with Fontan palliation, and in the preoperative anesthesia consultation it is of paramount importance to define if this group of

Faraoni et al. investigated the post-operative outcomes in children with and without CHD undergoing noncardiac surgery [1]. This study was performed using data from the 2012 pediatric database of the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP Pediatric). They included elective versus emergent surgery, and different surgical types (i.e., thoracic, neurological, orthopedic, general pediatric (including ear, nose, and throat), plastics and urogynecology).

Children with CHD were classified into three groups: minor, major and severe CHD, as defined in the ACS NSQIP database, based on residual lesion burden and

This authors evaluated in the cohort of patients if the presence of major or severe CHD is associated with an increased risk of anesthesia and surgery. Of the 51,008 children included in the database, 4520 children with CHD underwent noncardiac surgery. After propensity score matching, they included 2805 children with minor CHD, 1272 with major CHD, and 417 with severe CHD. The overall mortality was significantly higher in children presenting moderate (3.9%) and severe (8.2%) CHD compared with controls (1.2% and 1.7% respectively). No statistical difference was observed in children with minor CHD (1.5%) and their controls (1%). The conclusions of the authors are children with major and severe CHD undergoing noncardiac surgery have an increased risk of mortality, and a higher incidence of post-operative reintubation compared with matched controls undergoing comparable procedures. In the study, overall mortality in children with CHD was 2.8% compared with 1.2% in children without CHD, corresponding to a 2.3-fold higher mortality rate in children with CHD. In conclusion, children with major or

is identified. Surgical interventions are necessary in certain cases.

Bypassing the pulmonary vasculature can partially reverse the restrictions to CO imposed by the neoportal system. A Fontan fenestration allows flow to bypass the neoportal system, which results in venous decongestion and increase in CO. However, while a fenestration can increase overall output, it does so at the expense of diminished arterial oxygen saturation. Nevertheless, in the setting of a fenestration, the increase in CO can result in an increase in peripheral oxygen

**112**

severe CHD who undergo noncardiac surgery have an increased risk of mortality with a higher incidence of life-threatening postoperative outcomes compared with children without CHD [1].

Then Faraoni et al., developed a validation of a risk stratification score for children with CHD undergoing noncardiac surgery [13]. The objective of this study was to identify the predictors for in-hospital mortality, and to develop a risk stratification score that could be used to help decision making and the development of perioperative management guidelines. This study was performed using data from the 2012, 2013, and 2014 pediatric databases of the ACS NSQIP and included all children with major or severe CHD as previously defined. They were able to identify eight predictors for in-hospital mortality in children with major and severe CHD undergoing noncardiac surgery: four were preoperative markers of critical illness (inotropic support, mechanical ventilation, preoperative cardiopulmonary resuscitation (CPR) and acute or chronic kidney injury), the type of lesion (e.g., single ventricle physiology (SVP)) and the functional severity of heart disease (e.g., severe CHD). All of them were excellent predictors of in-hospital mortality (**Table 2**).

Children with SVP were identified to be at high risk for perioperative complications and at increased risk of in-hospital mortality regardless of their functional status. Although ACS NSQIP Pediatric database allows identification of patients with SVP, does not provide accurate information on their specific stage of palliation [13].

The 2018 ACC/AHA guidelines for the management of adults with CHD (ACHD) stated that patients with ACHD may have greater operative risk than patients without ACHD. The guidelines recommend optimization before and close surveillance after invasive procedures regardless of the complexity of the anatomic defect or type of procedure. In patients with ACHD, especially those with complex disease (ACHD AP classification II and III) and/or whose disease has progressed (stages B, C, D), noncardiac surgical and interventional procedures should be performed in a hospital with or in consultation with experts in ACHD when possible. Because the inability to access resources or urgent conditions may preclude transfer or timely consultation, collaboration with members of the multidisciplinary ACHD team may be helpful [14].

1. Critical illness: inotropic support, mechanical ventilation, preoperative CPR, acute or chronic kidney injury

2. SVP

3. Functional severity: major CHD and severe CHD

*CPR, cardiopulmonary resuscitation; SVP, single ventricle physiology; CHD, congenital heart disease.*

### **Table 2.**

*Predictors of in-hospital mortality.*

### **3.2 Multisystem approach for Fontan patient evaluation**

Even though mortality in patients with SVP who undergo staged palliation has decreased significantly over the past decades, Fontan physiology and its long-term complications (e.g., arrhythmias, circulatory failure, multi-organic compromise, etc.) continue to pose significant challenges in the management of children and adults requiring anesthesia for noncardiac surgical or invasive procedures.

The preoperative evaluation of the patient with Fontan physiology involves a thorough history and physical examination as well as review of recent cardiovascular imaging studies, using a multisystem approach with attention to the unique characteristics of this patient population (**Figure 7**).

In the preoperative evaluation the anesthesiologist must define if the Fontan patient has a normal functioning or a failing Fontan, since it has important implications in the anesthetic management and in the perioperative care.

Medical history should focus on changes in health status, exercise capacity, hospital admissions, current medication and allergies. In addition to clinical examination, medical records, electrocardiography, chest X-ray, echocardiography, most recent catheterization, CMR imaging and laboratory data are invaluable to elucidate cardiac anatomy and the Fontan circuit, oxygen saturation, transpulmonary gradient and to assess ventricular function and valve regurgitation.

The physical exam of a well-functioning Fontan despite the univentricular pathology should be relatively unremarkable. The patient should be acyanotic, warm and well perfused. Precordial auscultation should be devoid of murmurs and peripheral arterial pulses are palpable. The arterial oxygen saturation is typically between 90% and 95% [5].

Failing Fontan physiology involves multiple organ systems: ventricular failure, hepatic disfunction, long lasting pleural effusions, pulmonary hypertension, PLE, plastic bronchitis. Symptoms indicative of a failing Fontan include dyspnea, fatigue, decline in exercise tolerance, weight gain or volume retention, palpitations, syncopal or pre-syncopal episodes, a new or worsening murmur, hepatomegaly, oxygen saturation below 90% and dyspnea [5]. Cardiomegaly and/ or pleural effusions may herald a failing Fontan.

### *3.2.1 Cardiovascular evaluation*

### *3.2.1.1 Functional status and exercise capacity*

At peak exercise, a normal subject with a biventricular circuit can increase his CO by a factor of 5. In a patient with Fontan physiology, there is not physiologic mechanisms to allow for a similar increase in CO because the maximal mean venous pressure rarely reaches 30 mmHg, there is inability to power blood through the pulmonary vasculature and subsequent blood acceleration, and the reactivity of PVR is

**115**

**Figure 7.**

*Physiopathological Approach of the Fontan Patient for Noncardiac Surgery for the Anesthesiologist*

attenuated or absent. These limitations combined, result in the diminished ability to augment CO in response to an increase in metabolic demand, therefore limiting the

Under resting conditions, the CO of a Fontan patient is 70–80% of what it would normally be for age and body surface area. During physical activity the limitations of the Fontan circuit are substantially magnified; a small difference of CO at rest can become a much larger difference during activity. At the best Fontan, the output is mildly decreased at rest with moderate capacity to increase flow during moderate exercise. In the failing Fontan patient, the output is severely reduced at rest and

Fontan patients have lived with less than ideal CO their entire lives and might not recognize symptoms or demonstrate overt manifestations of progressive decline

The New York Heart Association (NYHA) classification, originally established for patients with CHF, is now widely used in CHD. It represents a simple classification of exercise intolerance based on subjective symptoms. NYHA class does stratify patients, distinguishing patients with mild impairment from those with moderate or severe impairment of objective exercise capacity and the presence and severity of symptoms signify a worse objective exercise capacity. In the study of Diller et al., ACHD patients had exercise capacities as poor as those of patients with acquired

Fontan patient to perform exercise (**Figure 8**).

*Multisystem approach for Fontan patient preoperative evaluation.*

barely augments during minimal exercise [2] (**Figure 9**).

in functional status until deterioration is quite advanced [6].

*DOI: http://dx.doi.org/10.5772/intechopen.93388*

*Physiopathological Approach of the Fontan Patient for Noncardiac Surgery for the Anesthesiologist DOI: http://dx.doi.org/10.5772/intechopen.93388*

### **Figure 7.**

*Advances in Complex Valvular Disease*

kidney injury

*Predictors of in-hospital mortality.*

2. SVP

**Table 2.**

procedures.

between 90% and 95% [5].

*3.2.1 Cardiovascular evaluation*

**3.2 Multisystem approach for Fontan patient evaluation**

3. Functional severity: major CHD and severe CHD

characteristics of this patient population (**Figure 7**).

tions in the anesthetic management and in the perioperative care.

ent and to assess ventricular function and valve regurgitation.

or pleural effusions may herald a failing Fontan.

*3.2.1.1 Functional status and exercise capacity*

Even though mortality in patients with SVP who undergo staged palliation has decreased significantly over the past decades, Fontan physiology and its long-term complications (e.g., arrhythmias, circulatory failure, multi-organic compromise, etc.) continue to pose significant challenges in the management of children and adults requiring anesthesia for noncardiac surgical or invasive

1. Critical illness: inotropic support, mechanical ventilation, preoperative CPR, acute or chronic

*CPR, cardiopulmonary resuscitation; SVP, single ventricle physiology; CHD, congenital heart disease.*

The preoperative evaluation of the patient with Fontan physiology involves a thorough history and physical examination as well as review of recent cardiovascular imaging studies, using a multisystem approach with attention to the unique

In the preoperative evaluation the anesthesiologist must define if the Fontan patient has a normal functioning or a failing Fontan, since it has important implica-

Medical history should focus on changes in health status, exercise capacity, hospital admissions, current medication and allergies. In addition to clinical examination, medical records, electrocardiography, chest X-ray, echocardiography, most recent catheterization, CMR imaging and laboratory data are invaluable to elucidate cardiac anatomy and the Fontan circuit, oxygen saturation, transpulmonary gradi-

The physical exam of a well-functioning Fontan despite the univentricular pathology should be relatively unremarkable. The patient should be acyanotic, warm and well perfused. Precordial auscultation should be devoid of murmurs and peripheral arterial pulses are palpable. The arterial oxygen saturation is typically

Failing Fontan physiology involves multiple organ systems: ventricular failure, hepatic disfunction, long lasting pleural effusions, pulmonary hypertension, PLE, plastic bronchitis. Symptoms indicative of a failing Fontan include dyspnea, fatigue, decline in exercise tolerance, weight gain or volume retention, palpitations, syncopal or pre-syncopal episodes, a new or worsening murmur, hepatomegaly, oxygen saturation below 90% and dyspnea [5]. Cardiomegaly and/

At peak exercise, a normal subject with a biventricular circuit can increase his CO by a factor of 5. In a patient with Fontan physiology, there is not physiologic mechanisms to allow for a similar increase in CO because the maximal mean venous pressure rarely reaches 30 mmHg, there is inability to power blood through the pulmonary vasculature and subsequent blood acceleration, and the reactivity of PVR is

**114**

*Multisystem approach for Fontan patient preoperative evaluation.*

attenuated or absent. These limitations combined, result in the diminished ability to augment CO in response to an increase in metabolic demand, therefore limiting the Fontan patient to perform exercise (**Figure 8**).

Under resting conditions, the CO of a Fontan patient is 70–80% of what it would normally be for age and body surface area. During physical activity the limitations of the Fontan circuit are substantially magnified; a small difference of CO at rest can become a much larger difference during activity. At the best Fontan, the output is mildly decreased at rest with moderate capacity to increase flow during moderate exercise. In the failing Fontan patient, the output is severely reduced at rest and barely augments during minimal exercise [2] (**Figure 9**).

Fontan patients have lived with less than ideal CO their entire lives and might not recognize symptoms or demonstrate overt manifestations of progressive decline in functional status until deterioration is quite advanced [6].

The New York Heart Association (NYHA) classification, originally established for patients with CHF, is now widely used in CHD. It represents a simple classification of exercise intolerance based on subjective symptoms. NYHA class does stratify patients, distinguishing patients with mild impairment from those with moderate or severe impairment of objective exercise capacity and the presence and severity of symptoms signify a worse objective exercise capacity. In the study of Diller et al., ACHD patients had exercise capacities as poor as those of patients with acquired

### **Figure 8.**

*CO and exercise level. At peak exercise, a normal subject with a biventricular circuit can increase his CO by a factor of 5. The Fontan patient has a diminished ability to augment CO in response to increased metabolic demand, and therefore limit the ability of a patient with a Fontan to perform exercise (CO, cardiac output; LV, left ventricle).*

**Figure 9.** *Cardiac output in normal heart and the Fontan patient, during exercise and at rest. (CO, cardiac output).*

CHF, even though the latter were much older [15]. Although NYHA class is used widely, the underlying criteria are subjective and the reproducibility is low.

In contrast to NYHA, cardiopulmonary exercise testing is the best way to assess exercise performance in ACHD patients, because it gives accurate, reproducible and quantifiable data on cardiac and respiratory performance, also allowing the assessment of unexpected deterioration. Most Fontan patients have undergone two or three re-operations, and this can lead to the development of restrictive lung defects in many patients. This finding, in addition to the restrictions in augmentation of the CO on exercise, contribute to a reduction in the measured peak oxygen uptake (peak VO2), with average Fontan patients achieving a peak VO2 of 60–70% that of age/sex/size-matched controls [7]. Longitudinal studies of late adolescents and young adults demonstrate this point well; as patients progress to late adolescence

**117**

*Physiopathological Approach of the Fontan Patient for Noncardiac Surgery for the Anesthesiologist*

and early adulthood, exercise capacity tends to continue to decline by about 2.6% predicted per year [9, 16]. In many forms of CHD the cutoff for the development of symptoms of heart failure is an exercise capacity of 45–50% of the predicted value. Assuming a starting point of 65% predicted for age and at the onset of puberty in a Fontan patients, and calculating a decline of 2.6% per year thereafter, the cutoff of 45% predicted can be expected to be reached at the end of the second decade of life [2] and as typically occurs in the third decade of life, hospitalization rates and symptoms increase significantly [6, 16, 17]. Cardiopulmonary exercise testing can objectively quantify exercise tolerance and help guided therapy, therefore, peak VO2

is an essential component of a tailored exercise and activity program [6].

In the Mayo Clinic cohort [10], 80% of the patients after the Fontan operation rated their current health as excellent, and a similar percentage of patients thought that their physical status was improved. This is consistent with previously reported data suggesting that patients tend to perceive themselves as having a higher func-

In the preoperative evaluation, it is important to recognize that NYHA class underestimates the true degree of exercise limitation in Fontan patients. It is likely that Fontan patients have made lifelong adaptations to their cardiovascular disease and its slow progression, so they are not aware of the true extent of their exercise intolerance and could consider themselves asymptomatic. The presence and severity of symptoms signify a worse objective exercise capacity in these patients [15].

Some factors contributing to arrhythmogenicity include systolic and diastolic dysfunction, atrioventricular valvular regurgitation, atrial enlargement, multiple cardiac procedures, myocardial fibrosis, APCs, intra-atrial tunnels and an abnormal array of atrial fibers. The incidence of late atrial tachyarrhythmias approaches 50% in the adult population after Fontan palliation and often results in decreased

In the Mayo Clinic cohort [10], the diagnosis of new clinical arrhythmias during long term follow-up was present in 44% of the patients. Freedom of arrhythmia at 10, 20 and 30 years after the Fontan operation was 71%, 42% and 24% respectively. The majority of this patients had atrial fibrillation or flutter, and a smaller proportion presented, atrial tachycardia, re-entrant supra ventricular tachycardia and

Sinus node dysfunction is common in all Fontan variants, with prevalence rates

In the preoperative evaluation one should recognize the history of such arrhyth-

In the preoperative evaluation determine the patient's saturation on room air, which in a well-functioning Fontan should be between 90% and 95%. In the case of

desaturation, it is important elucidate the cause of hypoxemia (**Table 3**).

as high as 40%. Sinoatrial dysfunction and bradyarrhythmias may necessitate placement of a dual-chamber pacemaker or resynchronization therapy [5]. In general, many strategies have been employed to reduce the arrhythmia burden, including oral antiarrhythmics and catheter ablation. A catheter-based ablation strategy has a considerably lower success rate in Fontan patients compared with other forms of CHD, with recurrences or new arrhythmias in approximately

exercise capacity, fatigue and congestive heart failure [5–7, 10].

*DOI: http://dx.doi.org/10.5772/intechopen.93388*

tional status compared with control populations.

*3.2.1.2 Arrhythmias*

ventricular tachycardia.

50% within 4–5 years [6].

*3.2.2 Pulmonary evaluation*

mias and history electrophysiological procedures.

### *Physiopathological Approach of the Fontan Patient for Noncardiac Surgery for the Anesthesiologist DOI: http://dx.doi.org/10.5772/intechopen.93388*

and early adulthood, exercise capacity tends to continue to decline by about 2.6% predicted per year [9, 16]. In many forms of CHD the cutoff for the development of symptoms of heart failure is an exercise capacity of 45–50% of the predicted value. Assuming a starting point of 65% predicted for age and at the onset of puberty in a Fontan patients, and calculating a decline of 2.6% per year thereafter, the cutoff of 45% predicted can be expected to be reached at the end of the second decade of life [2] and as typically occurs in the third decade of life, hospitalization rates and symptoms increase significantly [6, 16, 17]. Cardiopulmonary exercise testing can objectively quantify exercise tolerance and help guided therapy, therefore, peak VO2 is an essential component of a tailored exercise and activity program [6].

In the Mayo Clinic cohort [10], 80% of the patients after the Fontan operation rated their current health as excellent, and a similar percentage of patients thought that their physical status was improved. This is consistent with previously reported data suggesting that patients tend to perceive themselves as having a higher functional status compared with control populations.

In the preoperative evaluation, it is important to recognize that NYHA class underestimates the true degree of exercise limitation in Fontan patients. It is likely that Fontan patients have made lifelong adaptations to their cardiovascular disease and its slow progression, so they are not aware of the true extent of their exercise intolerance and could consider themselves asymptomatic. The presence and severity of symptoms signify a worse objective exercise capacity in these patients [15].

## *3.2.1.2 Arrhythmias*

*Advances in Complex Valvular Disease*

**116**

**Figure 9.**

**Figure 8.**

*left ventricle).*

CHF, even though the latter were much older [15]. Although NYHA class is used widely, the underlying criteria are subjective and the reproducibility is low.

*Cardiac output in normal heart and the Fontan patient, during exercise and at rest. (CO, cardiac output).*

*CO and exercise level. At peak exercise, a normal subject with a biventricular circuit can increase his CO by a factor of 5. The Fontan patient has a diminished ability to augment CO in response to increased metabolic demand, and therefore limit the ability of a patient with a Fontan to perform exercise (CO, cardiac output; LV,* 

In contrast to NYHA, cardiopulmonary exercise testing is the best way to assess exercise performance in ACHD patients, because it gives accurate, reproducible and quantifiable data on cardiac and respiratory performance, also allowing the assessment of unexpected deterioration. Most Fontan patients have undergone two or three re-operations, and this can lead to the development of restrictive lung defects in many patients. This finding, in addition to the restrictions in augmentation of the CO on exercise, contribute to a reduction in the measured peak oxygen uptake (peak VO2), with average Fontan patients achieving a peak VO2 of 60–70% that of age/sex/size-matched controls [7]. Longitudinal studies of late adolescents and young adults demonstrate this point well; as patients progress to late adolescence

Some factors contributing to arrhythmogenicity include systolic and diastolic dysfunction, atrioventricular valvular regurgitation, atrial enlargement, multiple cardiac procedures, myocardial fibrosis, APCs, intra-atrial tunnels and an abnormal array of atrial fibers. The incidence of late atrial tachyarrhythmias approaches 50% in the adult population after Fontan palliation and often results in decreased exercise capacity, fatigue and congestive heart failure [5–7, 10].

In the Mayo Clinic cohort [10], the diagnosis of new clinical arrhythmias during long term follow-up was present in 44% of the patients. Freedom of arrhythmia at 10, 20 and 30 years after the Fontan operation was 71%, 42% and 24% respectively. The majority of this patients had atrial fibrillation or flutter, and a smaller proportion presented, atrial tachycardia, re-entrant supra ventricular tachycardia and ventricular tachycardia.

Sinus node dysfunction is common in all Fontan variants, with prevalence rates as high as 40%. Sinoatrial dysfunction and bradyarrhythmias may necessitate placement of a dual-chamber pacemaker or resynchronization therapy [5].

In general, many strategies have been employed to reduce the arrhythmia burden, including oral antiarrhythmics and catheter ablation. A catheter-based ablation strategy has a considerably lower success rate in Fontan patients compared with other forms of CHD, with recurrences or new arrhythmias in approximately 50% within 4–5 years [6].

In the preoperative evaluation one should recognize the history of such arrhythmias and history electrophysiological procedures.

### *3.2.2 Pulmonary evaluation*

In the preoperative evaluation determine the patient's saturation on room air, which in a well-functioning Fontan should be between 90% and 95%. In the case of desaturation, it is important elucidate the cause of hypoxemia (**Table 3**).

### **Low pulmonary venous saturation:**


### **Right-to-left shunt:**


### **Table 3.**

*Common sources of hypoxemia in the Fontan patient.*

Persistent or recurrent pleural effusions can be a source of hypoxemia in Fontan patients. Systemic oxygen desaturation can also be found because of intrapulmonary shunting due to arteriovenous malformations. The unequal distribution of hepatic blood flow to the pulmonary system is the most accepted etiology. Less hepatic blood flow to the pulmonary vasculature makes it more prone to developing arteriovenous malformations [5].

As pointed before, most Fontan patients have undergone at least two or three open chest procedures and may have undergone a thoracotomy that leads to a restrictive lung defect. Nearly half of all ACHD patients have lung disease with a primarily restrictive pattern, which represents an independent predictor for mortality [18]. The etiology is multifactorial: intrinsic causes of restrictive lung disease range from decrease in the pulmonary blood flow, development of arteriovenous malformations at the level of the lung and the long standing persistent abnormal physiology that contributes to the changes in the pulmonary vascular bed. Extrinsic causes are related to the multiple re-operations, congenital chest wall and spinal deformities, preexisting muscle weakness, all having an effect in the pulmonary mechanics. Other contributing factors as extended mechanical ventilation due to critical illness during childhood, chronic aspiration, acquire muscle weakness, and poor nutrition, can result in impaired pulmonary function [18].

Plastic bronchitis is a rare complication reported in less than 1–2% of Fontan patients. It is characterized by bronchial casts, with potential for airway obstruction. Segmental airway obstruction can result in regional atelectasis and hypoxemia. Dyspnea, chronic cough, and recurrent expectoration of rubber airway casts are characteristic of this disorder. Plastic bronchitis can be life-threatening on presentation [6].

Another source of hypoxemia in Fontan patients include persistent right-to-left shunting. Maintaining adequate preload for the SV is challenging in the Fontan patient, and it relies on a number of "auto-regulatory" phenomena, including the development of veno-venous collateral vessels that pass from the systemic veins to the pulmonary venous circulation shunting deoxygenated blood directly into the oxygenated pulmonary venous system or the common atrium. The downside to maintaining an adequate preload and CO is the profound cyanosis that can be worsened by physical exertion (**Figure 6**).

The strategy employed in many centers is a catheter based embolization of these vessels. The impact on the symptoms or survival has not been determined, and further reduction in oxygen saturation post-procedure, suggest a high recurrence rate [5, 7].

Systemic-to-PA collaterals are a frequent finding in cyanotic Fontan patients. Left alone, these collateral vessels may result in pulmonary hypertension and failure of the Fontan circulation.

**119**

respectively [10].

*Physiopathological Approach of the Fontan Patient for Noncardiac Surgery for the Anesthesiologist*

Hypercoagulability and hypocoagulability both are more prevalent in patients

After the Fontan operation, patients have been reported to have numerous clotting abnormalities including deficiencies of protein C, protein S and antithrombin III. Hypercoagulability combined with decreased CO, a nonpulsatile low flow state to the pulmonary circulation, a high incidence of atrial arrhythmias and the presence of prosthetic material, contribute to a higher risk for thrombus formation in

Some studies have reported a rate of thrombus formation of up to 20% in patients after a Fontan procedure and they are a source of significant morbidity and mortality [5, 9]. The incidence of thromboemboli after the extracardiac cavopulmonary connection is estimated to be 7.1% at 10 years after Fontan completion. This can result in pulmonary emboli, systemic emboli through a patent fenestration and systemic thrombi in the atria, PA stump or rudimentary

Approximately 10% of patients within the first 5 years after Fontan palliation, develop thrombotic occlusion of central veins, this can result in pulmonary emboli and in SVC obstruction. Clinicians should not assume patency or availability of venous access for central monitoring of the subclavian, internal jugular or femoral vessels. The anesthesiologist relies on cardiac catheterization reports and Doppler ultrasound to assess vascular patency of the venous and arterial tree [5]. Many patients are on anticoagulants or aspirin, especially those with thrombosis history or with a failing Fontan with any of the following manifestations: ventricular failure, hepatic disfunction, long lasting pleural effusions, pulmonary hypertension,

The reported incidence of stroke ranges from 3% to 20%. Cerebral vascular accidents have been reported in adult patients with Fontan physiology secondary to atrial arrhythmias, hematologic derangements and systemic embolic events [5].

Fontan physiology, in particular, with the multitude of insults from persistent congestive hepatopathy, hypoxia, and ischemic hepatitis, has a high incidence of

There is growing recognition of the deleterious effects of systemic venous hypertension on hepatic function and the development of fibrosis, cirrhosis and

PLE is a cardinal sign of failing Fontan palliation. Pleural effusions with associated decreases in oxygen saturation, peripheral edema, ascites, malabsorption and loss of immunoglobulins are consistent findings in patients with PLE. Hypoalbuminemia, decreased total protein and stool positive for alpha 1-antitrypsin

In the Mayo Clinic cohort [10] was found that although the Fontan procedure has improved overall survival in patients with SV, various events impact long-term survival, including diagnosis of PLE. The overall incidence of PLE in this study was 9%. Overall mortality in the PLE cohort was 72% during 7 + − 7.4 years of followup. Survival at 5, 10, and 20 years after PLE diagnosis was 50%, 35% and 19%,

*DOI: http://dx.doi.org/10.5772/intechopen.93388*

*3.2.3 Hematologic evaluation*

with Fontan physiology [18].

the Fontan patient [9].

PLE, and plastic bronchitis.

*3.2.4 Neurologic evaluation*

liver dysfunction [18].

hepatocellular carcinoma.

confirm the diagnosis [5, 7].

*3.2.5 Hepatic and gastrointestinal evaluation*

ventricle [9].

*Physiopathological Approach of the Fontan Patient for Noncardiac Surgery for the Anesthesiologist DOI: http://dx.doi.org/10.5772/intechopen.93388*
