*3.2.3 Hematologic evaluation*

*Advances in Complex Valvular Disease*

**Low pulmonary venous saturation:**

• Veno-venous collateral vessels • Persistent fenestration

*Common sources of hypoxemia in the Fontan patient.*

• Pulmonary arteriovenous malformations

• Pleural effusions

• Baffle leak

**Table 3.**

• Intrinsic lung disease • Plastic bronchitis **Right-to-left shunt:**

arteriovenous malformations [5].

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

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

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

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

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

poor nutrition, can result in impaired pulmonary function [18].

**118**

presentation [6].

worsened by physical exertion (**Figure 6**).

of the Fontan circulation.

Hypercoagulability and hypocoagulability both are more prevalent in patients with Fontan physiology [18].

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 the Fontan patient [9].

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 ventricle [9].

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, PLE, and plastic bronchitis.

### *3.2.4 Neurologic evaluation*

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].

### *3.2.5 Hepatic and gastrointestinal evaluation*

Fontan physiology, in particular, with the multitude of insults from persistent congestive hepatopathy, hypoxia, and ischemic hepatitis, has a high incidence of liver dysfunction [18].

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

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 confirm the diagnosis [5, 7].

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%, respectively [10].

### *3.2.6 Renal evaluation*

ACHD patients have a prevalence of renal dysfunction 18 to 35 fold higher compared to the general population. Renal dysfunction is seen in 50% of Fontan patients, including a 15% presenting with severe reduction of glomerular filtration rate [19].

### *3.2.7 Imaging*

Preoperatively the use of recent or previous imaging studies allows the proper assessment of the Fontan cardiac function, pathway and vascular anatomy.

Chest radiography can present with abnormalities consistent with a failing Fontan, including cardiomegaly, pleural effusion and pulmonary edema.

To evaluate systolic and diastolic ventricular function is important to perform a preoperative TTE or TEE, it also evaluates atrioventricular valve function, the presence of an open fenestration and detects intracardiac thrombi.

Cardiac catheterization evaluates the Fontan hemodynamics measuring CAP, CVP, ventricular end-diastolic pressure, sampling blood along the vessels and chambers to determine their saturations and, CI calculation with the Fick Method. A high preoperative CAP suggests poor ventricular function, atrioventricular valve dysfunction or the presence of aortopulmonary collaterals. Isolated high CVP with low CAP reflects increased PVR or an obstruction along the Fontan pathway.

Cardiac catheterization can also allow the measurement of pressure gradients of obstructive lesions in the vena cava, pulmonary vessels and across the atrial septal defect. It is also used to assess the presence of right-to-left shunts causing desaturation as baffle leaks, fenestrations, decompressing veno-venous collateral vessels, pulmonary arteriovenous malformations and systemic to pulmonary collaterals. Catheter-based interventions may be required to alleviate obstruction in the Fontan pathway, for managing profound cyanosis or for stenting of branch PA stenosis or venous pathway obstruction [7].

CMR imaging is increasingly used in assessing anatomy, flow, and function in the Fontan patient without a pacemaker [5, 7]. It is used to asses Fontan pathway flow, it also assess pulmonary venous return to exclude obstruction. In addition it can provide with an accurate assessment of the ventricular function and assessment of the branch PAs, and in the ventricular outflow pathway it can exclude recoarctation or narrowing [7].

Urgent and emergent noncardiac surgeries or invasive procedures should not be delayed for sophisticated imaging in the preoperative evaluation, but the anesthesiologist should be aware of the previous studies and the actual anatomy of the patient.

## **4. Intraoperative management**

Although there are guidelines for the perioperative management of patients with CHD undergoing noncardiac surgery [14, 18, 20–22], these recommendations are based on experience and expert opinion. The diversity of structural malformations in CHD, each with specific physiologic perturbations, hemodynamic consequences, and functional limitations, makes the development of general guidelines for perioperative management challenging [13].

### **4.1 Hemodynamic monitoring**

Standard American Society of Anesthesiologists (ASA) intraoperative monitoring is often adequate for patients with a well-functioning Fontan, particularly for procedures in which minimal hemodynamic derangements or fluid shifts are expected.

**121**

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

For the failing Fontan patient or well-functioning Fontan patient presenting for more complex surgical procedures, intra-arterial blood pressure monitoring is useful for beat-to-beat monitoring of blood pressure and blood sampling to asses sufficient systemic perfusion and adequate balance in oxygen delivery and consumption by measuring laboratory values such as lactate levels and central venous

Upper-extremity blood pressure (noninvasive and radial arterial catheters) should be measured in the arm opposite to a previous Blalock-Taussig shunt (subclavian artery-to-PA) to avoid falsely low blood pressure measurements [5]. It should be noted that CVP actually reflects mean PA pressure (MPAP) in

Intraoperative placement of transcutaneous defibrillator pads is prudent in

Regarding vascular access, abnormal vascular anatomy of the initial CHD, postsurgical changes, multiple vascular interventions, and prior thrombus formation can pose significant challenges when patients are in need of vascular access [5]. Even though upper central venous access is possible in patients with Fontan circulation, exact knowledge of vascular anatomy is crucial for venous cannulation. Venous mapping can be highly valuable before any intervention, and access obtained by interventional radiologists under direct fluoroscopic guidance may be required. A graph depicting which vascular access is patent in a particular patient should be readily available to the care team in order to avoid difficulty in placing

Another consideration when obtaining and maintaining vascular access is the risk of paradoxic emboli in the presence of right-to-left or bidirectional shunting through the post-surgical fenestration. Entrained air and dislodged thrombotic or infectious material can lead to paradoxic emboli and to infarction of brain, gut, kidney, and other end organs [18]. Before the administration of intravenous fluids or medications, all air must be evacuated meticulously and filtered to avoid systemic air embolism and

It is recommended that central venous catheters be removed as soon as possible

There are important anesthetic considerations for the patient with Fontan

The mainstay of anesthetic management is to maintain an optimal transpulmonary gradient in order to achieve an adequate pulmonary blood flow and CO. The Fontan (CVP = MPAP) is typically 10 to 15 mmHg with a transpulmonary gradient of 7 mmHg. It is helpful to determine CAP values from the preoperative catheterization because the anesthesiologist will not monitor this value in the operating room.

The differential diagnosis of acute oxygen desaturation in the intraoperative

use of air filters can mitigate the risk of accidental air entrainment [5, 18].

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

patients with a history of arrhythmias [5].

oxygenation [5, 18].

Fontan patients.

**4.2 Vascular access**

lines in an emergency [18].

**4.3 Anesthetic goals**

physiology.

to avoid thrombotic complications [5].

*4.3.2 Differential diagnosis of desaturation*

*4.3.1 Maintenance an optimal transpulmonary gradient*

period may include factors unique to the Fontan patient.

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

For the failing Fontan patient or well-functioning Fontan patient presenting for more complex surgical procedures, intra-arterial blood pressure monitoring is useful for beat-to-beat monitoring of blood pressure and blood sampling to asses sufficient systemic perfusion and adequate balance in oxygen delivery and consumption by measuring laboratory values such as lactate levels and central venous oxygenation [5, 18].

Upper-extremity blood pressure (noninvasive and radial arterial catheters) should be measured in the arm opposite to a previous Blalock-Taussig shunt (subclavian artery-to-PA) to avoid falsely low blood pressure measurements [5].

It should be noted that CVP actually reflects mean PA pressure (MPAP) in Fontan patients.

Intraoperative placement of transcutaneous defibrillator pads is prudent in patients with a history of arrhythmias [5].

### **4.2 Vascular access**

*Advances in Complex Valvular Disease*

venous pathway obstruction [7].

**4. Intraoperative management**

erative management challenging [13].

**4.1 Hemodynamic monitoring**

ACHD patients have a prevalence of renal dysfunction 18 to 35 fold higher compared to the general population. Renal dysfunction is seen in 50% of Fontan patients, including a 15% presenting with severe reduction of glomerular filtration rate [19].

Preoperatively the use of recent or previous imaging studies allows the proper

To evaluate systolic and diastolic ventricular function is important to perform a preoperative TTE or TEE, it also evaluates atrioventricular valve function, the

Cardiac catheterization evaluates the Fontan hemodynamics measuring CAP, CVP, ventricular end-diastolic pressure, sampling blood along the vessels and chambers to determine their saturations and, CI calculation with the Fick Method. A high preoperative CAP suggests poor ventricular function, atrioventricular valve dysfunction or the presence of aortopulmonary collaterals. Isolated high CVP with low CAP reflects increased PVR or an obstruction along the Fontan pathway.

Cardiac catheterization can also allow the measurement of pressure gradients of obstructive lesions in the vena cava, pulmonary vessels and across the atrial septal defect. It is also used to assess the presence of right-to-left shunts causing desaturation as baffle leaks, fenestrations, decompressing veno-venous collateral vessels, pulmonary arteriovenous malformations and systemic to pulmonary collaterals. Catheter-based interventions may be required to alleviate obstruction in the Fontan pathway, for managing profound cyanosis or for stenting of branch PA stenosis or

CMR imaging is increasingly used in assessing anatomy, flow, and function in the Fontan patient without a pacemaker [5, 7]. It is used to asses Fontan pathway flow, it also assess pulmonary venous return to exclude obstruction. In addition it can provide with an accurate assessment of the ventricular function and assessment of the branch PAs, and in the ventricular outflow pathway it can exclude recoarctation or narrowing [7]. Urgent and emergent noncardiac surgeries or invasive procedures should not be delayed for sophisticated imaging in the preoperative evaluation, but the anesthesiologist should be aware of the previous studies and the actual anatomy of the patient.

Although there are guidelines for the perioperative management of patients with CHD undergoing noncardiac surgery [14, 18, 20–22], these recommendations are based on experience and expert opinion. The diversity of structural malformations in CHD, each with specific physiologic perturbations, hemodynamic consequences, and functional limitations, makes the development of general guidelines for periop-

Standard American Society of Anesthesiologists (ASA) intraoperative monitoring is often adequate for patients with a well-functioning Fontan, particularly for procedures in which minimal hemodynamic derangements or fluid shifts are expected.

assessment of the Fontan cardiac function, pathway and vascular anatomy. Chest radiography can present with abnormalities consistent with a failing

Fontan, including cardiomegaly, pleural effusion and pulmonary edema.

presence of an open fenestration and detects intracardiac thrombi.

*3.2.6 Renal evaluation*

*3.2.7 Imaging*

**120**

Regarding vascular access, abnormal vascular anatomy of the initial CHD, postsurgical changes, multiple vascular interventions, and prior thrombus formation can pose significant challenges when patients are in need of vascular access [5].

Even though upper central venous access is possible in patients with Fontan circulation, exact knowledge of vascular anatomy is crucial for venous cannulation. Venous mapping can be highly valuable before any intervention, and access obtained by interventional radiologists under direct fluoroscopic guidance may be required. A graph depicting which vascular access is patent in a particular patient should be readily available to the care team in order to avoid difficulty in placing lines in an emergency [18].

Another consideration when obtaining and maintaining vascular access is the risk of paradoxic emboli in the presence of right-to-left or bidirectional shunting through the post-surgical fenestration. Entrained air and dislodged thrombotic or infectious material can lead to paradoxic emboli and to infarction of brain, gut, kidney, and other end organs [18]. Before the administration of intravenous fluids or medications, all air must be evacuated meticulously and filtered to avoid systemic air embolism and use of air filters can mitigate the risk of accidental air entrainment [5, 18].

It is recommended that central venous catheters be removed as soon as possible to avoid thrombotic complications [5].

### **4.3 Anesthetic goals**

There are important anesthetic considerations for the patient with Fontan physiology.

### *4.3.1 Maintenance an optimal transpulmonary gradient*

The mainstay of anesthetic management is to maintain an optimal transpulmonary gradient in order to achieve an adequate pulmonary blood flow and CO. The Fontan (CVP = MPAP) is typically 10 to 15 mmHg with a transpulmonary gradient of 7 mmHg. It is helpful to determine CAP values from the preoperative catheterization because the anesthesiologist will not monitor this value in the operating room.

### *4.3.2 Differential diagnosis of desaturation*

The differential diagnosis of acute oxygen desaturation in the intraoperative period may include factors unique to the Fontan patient.

Right-to-left shunts become important causes of hypoxemia. Acute elevation of PVR may cause right-to-left shunting across a fenestration or a baffle leak with the consequent drop in the saturation of the patient. PVR may be decreased acutely with hyperventilation (pCO2 30 mmHg or pH 7.45) and increasing concentrations of oxygen. Usual sources of hypoxemia in the perioperative period such as endobronchial intubation, bronchospasm, and atelectasis always should be considered.

### *4.3.3 Respiratory management*

The circulatory arrangement of the Fontan amplifies the effects of respiratory mechanics upon venous return. Negative intra-thoracic pressure augments the antegrade flow from the SVC, IVC, and hepatic venous circulation into the pulmonary arterial tree. The work of breathing is a significant additional energy source to the circulation in these patients. Normal negative pressure inspiration has been shown to increase pulmonary blood flow in patients after the TCPC [3]. Physiologically there is a correlation between total hepatic venous flow and respiration. During inspiration there is marked increase in hepatic venous contribution to the total venous return, due to a dual effect on venous pressure and compression of the liver by diaphragmatic decent. The liver acts as a sump of blood which can be drawn upon during inspiration [3].

Magnetic resonance flow measurements have shown that approximately 30% of the CO can be directly attributed to the work of breathing in patients after the TCPC [3]. In Fontan patients, inspiration resulted in increased ventricular filling at rest and during exercise [23].

The opposite happens with positive pressure ventilation (PPV). It has long been known that increasing levels of positive end-expiratory pressure (PEEP) during PPV are adverse to the Fontan circulation. The available data suggests a linear relationship between mean airway pressure and CI in these patients: the higher the mean airway pressure, the lower CI [3]. This can be explained by the effect of lung volumes on PVR, since both over-distention and collapse of alveoli, result in increases in PVR.

The management of these patients should therefore be directed towards minimizing mean airway pressure when these patients are being ventilated for cardiac and noncardiac procedures. Also, an early postoperative restoration of normal negative pressure ventilation can be beneficial in these patients.

Adjustments to minimize positive intra-thoracic pressure can be made using minimal PEEP, smaller tidal volumes, pressure-regulated ventilatory modes, or spontaneous ventilation with minimal pressure support [18], and avoid prolonged Valsalva maneuvers. One should maintain these patients with the minimum mean airway pressure compatible with normal oxygenation and adequate alveolar ventilation.

A sound strategy when using PPV would be to adjust ventilatory parameters that allows to achieve the lowest mean airway pressure, moderate alkalosis (pH 7.45, pCO2 35 mmHg), and one that reduces the risk of atelectasis. Fontan patients have tolerated PPV with minimal hemodynamic effects as long as proper ventilatory settings are used. Furthermore, it has been proposed that monitored anesthesia care without adequate ventilation may be more detrimental than the physiologic effects of PPV per se [5].

### *4.3.4 Circulatory management*

Fontan patients pose a particular clinical challenge for the anesthesiologist due to their abnormal physiology and high risk for adverse events. Pre-existing chronic end-organ dysfunction makes these patients susceptible to acute exacerbation or organ failure [18]. Information of baseline cardiac function and hemodynamics

**123**

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

from prior heart catheterizations can provide reference filling pressures to minimize

Fontan physiology patients are very sensitive to changes in preload, and high PPV settings can exacerbate hemodynamic instability as was explained before. Acute hypovolemia or vasodilation during critical illness can result in significant

The effect of vasoconstrictors in augmenting preload in Fontan physiology is unclear because the compliance of the venous capacity system is reduced, and also an increase in ventricular afterload, due to arterial vasoconstriction, can decrease forward flow [18]. Hypervolemia due to excessive fluid resuscitation or chronically in the failing Fontan, can result in a reduced CO due to a decreased pressure gradient between systemic arterial and venous capacity system. Global congestion can lead to impaired pulmonary blood flow and right-sided congestion with subsequent

Finding the optimal volume status that balances adequate preload, venous congestion and organ perfusion could be challenging and requires vigilance and significant experience with these complex pathophysiologic states. Defining the end point of fluid administration (Blood components, Crystalloids) should be a balance of the risks and benefits of resuscitation. It is important to have the baseline pressures, hemoglobin level, signs of inadequate oxygen delivery, and concurrent factors affecting hemodynamics in order to decide how much and which fluid

Universally important applicable components when managing hemodynamics in these patients include maintaining adequate heart rate and intrinsic sympathetic tone, avoiding increases in PVR, and limiting harm from elevated intra-thoracic or

Risks associated with medical intervention especially adrenergic agents are

Low-cardiac-output syndrome will manifest as hypotension, elevated CVP, metabolic and lactic acidosis, and low urine output in the intraoperative period. Pharmacologically improving ventricular compliance lowers the CAP and increases the transpulmonary gradient without raising CVP. Milrinone, with its lusitropic and pulmonary vasodilatory properties, is well suited for the Fontan patient. Because systolic performance is not generally the primary issue in the Fontan circulation, the role of inotropic agents is often limited, and lowering the SVR while maintaining preload can be challenging. Inodilators increase the contractility of the SV, but may not result in clinically significant more CO. There may be a role for inotropes in the Fontan patient with significant ventricular dysfunction but in general the role of

• Since prognosis of patients with univentricular heart has improved significantly in recent decades, this has resulted in the general anesthesiologist being able to meet at some point in his professional practice with this type of patients, whether to perform a noncardiovascular diagnostic or therapeutic procedure or noncardiac surgery. Therefore, the anesthesiologist must have an appropriate knowledge of Fontan's anatomy and physiology as well as those patients with failed Fontan in order to provide them with a correct preoperative evaluation and an adequate intraoperative and postoperative management, and to obtain the best results, thus achieving a better survival and quality of

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

hypotension.

the risk of over-resuscitation or under-resuscitation.

pulmonary edema, kidney and hepatic dysfunction.

requires a particular patient [18].

intra-abdominal pressures [18].

exacerbation of arrhythmias.

these agents is limited [2].

life in this population group.

**5. Conclusions**

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

from prior heart catheterizations can provide reference filling pressures to minimize the risk of over-resuscitation or under-resuscitation.

Fontan physiology patients are very sensitive to changes in preload, and high PPV settings can exacerbate hemodynamic instability as was explained before. Acute hypovolemia or vasodilation during critical illness can result in significant hypotension.

The effect of vasoconstrictors in augmenting preload in Fontan physiology is unclear because the compliance of the venous capacity system is reduced, and also an increase in ventricular afterload, due to arterial vasoconstriction, can decrease forward flow [18]. Hypervolemia due to excessive fluid resuscitation or chronically in the failing Fontan, can result in a reduced CO due to a decreased pressure gradient between systemic arterial and venous capacity system. Global congestion can lead to impaired pulmonary blood flow and right-sided congestion with subsequent pulmonary edema, kidney and hepatic dysfunction.

Finding the optimal volume status that balances adequate preload, venous congestion and organ perfusion could be challenging and requires vigilance and significant experience with these complex pathophysiologic states. Defining the end point of fluid administration (Blood components, Crystalloids) should be a balance of the risks and benefits of resuscitation. It is important to have the baseline pressures, hemoglobin level, signs of inadequate oxygen delivery, and concurrent factors affecting hemodynamics in order to decide how much and which fluid requires a particular patient [18].

Universally important applicable components when managing hemodynamics in these patients include maintaining adequate heart rate and intrinsic sympathetic tone, avoiding increases in PVR, and limiting harm from elevated intra-thoracic or intra-abdominal pressures [18].

Risks associated with medical intervention especially adrenergic agents are exacerbation of arrhythmias.

Low-cardiac-output syndrome will manifest as hypotension, elevated CVP, metabolic and lactic acidosis, and low urine output in the intraoperative period. Pharmacologically improving ventricular compliance lowers the CAP and increases the transpulmonary gradient without raising CVP. Milrinone, with its lusitropic and pulmonary vasodilatory properties, is well suited for the Fontan patient. Because systolic performance is not generally the primary issue in the Fontan circulation, the role of inotropic agents is often limited, and lowering the SVR while maintaining preload can be challenging. Inodilators increase the contractility of the SV, but may not result in clinically significant more CO. There may be a role for inotropes in the Fontan patient with significant ventricular dysfunction but in general the role of these agents is limited [2].
