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Address correspondence to Genevieve E. Staudt, MD, Assistant Professor of Anesthesiology. Division of Pediatric Cardiac Anesthesiology, Vanderbilt University Medical Center, Suite 3116. 37232. Nashville, TN.
Departments of Medicine and Pediatrics, Divisions of Cardiovascular Medicine and Pediatric Cardiology, Vanderbilt University Medical Center, Nashville, TN
Departments of Medicine and Pediatrics, Divisions of Cardiovascular Medicine and Pediatric Cardiology, Vanderbilt University Medical Center, Nashville, TN
The Fontan procedure is performed as the final stage of palliation for patients with single-ventricle congenital heart diseases, such as tricuspid atresia, hypoplastic left-heart syndrome, or severely unbalanced atrioventricular canal defect. It creates a functional series circulation in which all pulmonary blood flow is derived from the systemic venous return that subsequently supplies ventricular preload in the absence of a subpulmonic pumping chamber. Since its inception in 1971, surgical advancement in the Fontan procedure has led to improved long-term outcomes, with transplant-free survival reaching 84% at 20 years.
Redefining expectations of long-term survival after the Fontan procedure: Twenty-five years of follow-up from the entire population of Australia and New Zealand.
Rychik J, Atz AM, Celermajer DS, et al. Evaluation and management of the child and adult with Fontan circulation: A scientific statement from the American Heart Association [e-pub ahead of print[. Circulation. doi: 10.1161/cir.0000000000000696. Accessed May 1, 2022.
Notably, pregnancy and childbirth in patients with Fontan physiology place unique stress on an individual whose cardiac physiology already places them at high risk for multiorgan system complications, including cerebrovascular and thromboembolic events, heart failure, cyanosis, arrhythmias, and liver failure.
Redefining expectations of long-term survival after the Fontan procedure: Twenty-five years of follow-up from the entire population of Australia and New Zealand.
Although traditional pregnancy risk stratification scores categorically place parturients with Fontan physiology into a higher risk group, Fontan-specific guidelines do not exist for the peripartum period.
Management of pregnancy in patients with complex congenital heart disease: A scientific statement for healthcare professionals from the American Heart Association.
This critical void is due largely to limited peripartum outcomes data for the parturient with Fontan physiology. In this case series, the authors developed a framework for the peripartum management of this challenging population, highlighting the need for team-based management of high-risk patients.
The authors conducted a retrospective, single-center case series of Fontan parturients ≥15 years who delivered a live birth infant at Vanderbilt University Medical Center between 1999 to 2020. The study was approved by the Vanderbilt University Institutional Review Board. A RedCAP database containing demographic and phenotypic data of adult patients with congenital heart disease cared for at the authors’ institution was queried for the pregnant patients with Fontan physiology during the study period.
The females with incomplete records and those who were followed but ultimately delivered their infants at another institution were excluded (Fig 1). A chart review was performed by 3 independent reviewers and cumulative data were reviewed for accuracy.
Twelve patients with Fontan physiology had a total of 19 pregnancies, resulting in live births that received care at Vanderbilt University Medical Center. Four patients who received prenatal care at Vanderbilt University Medical Center and ultimately delivered 6 live births at an outside hospital were excluded from the present study (Fig 1). Of the remaining 8 patients, there were a total of 13 live births. Three patients had >1 live birth during the authors’ study period. The mean maternal age at the time of delivery was 25 (range 18-33 years old). The baseline characteristics, anatomy, and details of the pregnancy are presented below in Table 1.
One patient had a classic atriopulmonary connection (12%), whereas 7 patients (88%) underwent contemporary-era surgical Fontan palliation with total cavopulmonary anastomosis—71% lateral tunnel and 29% extracardiac (Table 1). All of the parturients had a systemic left ventricle. The baseline systemic ventricular ejection fraction (EF) was assessed at a median of 27 (range 1-60) days prior to delivery.
Antepartum Cardiovascular Status
The majority of pregnancies (11/13, 85%) began with an asymptomatic (New York Heart Association class I) female free of Fontan failure at the time of conception. Fontan failure was defined as death, transplant, diagnosis of protein-losing enteropathy, predicted peak VO2 <50% on cardiopulmonary exercise testing, or new loop diuretic dependence persisting throughout the postpartum period.
Two pregnancies in the same patient began with Fontan failure with reduced EF at baseline. No patient had more than mild-moderate atrioventricular valve regurgitation at the start of pregnancy. Baseline arrhythmias (3/13, 23%) and hypoxemia (7/13, 54%) were common, and many received anticoagulation therapy (5/13, 38% of total pregnancies). Standard pregnancy risk scores classified all pregnancies as complex; 100% were World Health Organization class 3, whereas 77% were ZAHARA score 2.5 and 23% were ZAHARA score 4.
Peripartum Results
Of the 13 deliveries, 77% were via caesarian section (C-section), and 23% were vaginal deliveries, all forceps-assisted. The majority of parturients delivered early (mean 35 weeks and 1 day), and 69% were preterm. Four (31%) deliveries were scheduled, whereas 9 (69%) were urgent. Of the scheduled cases, 2 (15%) were C-sections, and 2 (15%) were vaginal deliveries after a planned induction of labor (Table 1). Of the urgent cases, 38% were complicated by preterm labor, and 23% by premature rupture of membranes (Table 2). Ninety-two percent of parturients received epidural or combined spinal-epidural anesthesia (Table 3). The majority of parturients underwent invasive hemodynamic monitoring, with an arterial line (62%) placed prior to neuraxial blockade or general endotracheal anesthesia. One patient (8%) required intubation for a failed neuraxial blockade.
Table 2Pregnancy Complexity
N, %
WHO
1
0
2
0
3
100%
4
0
ZAHARA
2.5 (17.5%)
77%
4 (70%)
23%
HELLP
0%
PROM
23%
PTL
38%
C-section
77%
Abbreviations: HELLP, Hemolysis, Elevated Liver enzymes and Low Platelets; PROM, premature rupture of membranes; PTL, preterm labor; WHO, World Health Organization.
There was no maternal mortality in the peripartum period. However, 54% of pregnancies resulted in an acute complication in the peripartum period (Table 3; Fig 1)—2 pregnancies (15%) experienced a cerebrovascular accident (CVA) (including 1 patient receiving systemic anticoagulation at the time of the CVA), 2 pregnancies (15%) had worsening cyanosis resulting in prolonged hospitalization, and 1 pregnancy (8%) had worsening Fontan failure with reduced EF requiring intravenous (IV) diuretic therapy. In the authors’ cohort, 62% of pregnancies had a subsequent outpatient clinic visit with oxygen saturation in the arterial blood ≤92% within 1 week of delivery (Table 1). Two patients (15%) developed worsening hypoxemia during the peripartum period. Hypotension, defined as a decrease of systolic blood pressure >20% from baseline (15% of patients), was treated readily with intermittent doses of IV ephedrine and/or phenylephrine during the C-section in the presence of neuraxial blockade. No continuous vasoactive infusions were initiated in the peripartum period. For maternal complications, 23% of pregnancies were complicated by postpartum hemorrhage. Overall, the mean prepartum hemoglobin (Hgb) concentration was 13.0 g/dL (SD 1.8 g/dL) on admission to the hospital, whereas the mean Hgb at 24 hours postpartum was 10.5 g/dL (SD 1.64 g/dL). Transfusion was required only in 1 delivery (7.6%), when the patient received 2 units of packed red blood cells prior to the Hgb measurement at 24 hours postpartum. Only 33% of postpartum hemorrhage complications occurred in patients on chronic systemic anticoagulation. Maternal hemorrhage largely was due to placenta accreta, abruption, and placental infarction. One patient (8%) experienced maternal hemorrhage from retained products of conception. Preeclampsia occurred during 2 pregnancies (15%). The average hospital length of stay postpartum was 15 days (SD 16.3 days). Four patients (30%) were admitted to the intensive care unit for heart failure, hemorrhage, or CVA.
The majority of neonates were born prematurely (69%; mean 35.1 weeks, IQR 34.8 - 37.1 weeks). Nearly half (46%) of births were complicated by fetal growth restriction, and 31% of infants were small for gestational age. The Apgar scores at 1 and 5 minutes were a mean of 6.7 and 7.8 (SD 2.75, 2.54), respectively.
Discussion
Fontan pregnancies are high-risk and require a multidisciplinary approach to management. Given the expected doubling of the Fontan population in the next 20 years,
Redefining expectations of long-term survival after the Fontan procedure: Twenty-five years of follow-up from the entire population of Australia and New Zealand.
the authors anticipate a surge of Fontan pregnancies requiring specialized centers of multidisciplinary experts with knowledge of the anatomy and physiology of both Fontan palliation and pregnancy for their management. Teams of adult congenital heart disease cardiologists, maternal-fetal medicine, obstetric anesthesiology, and cardiac anesthesiology are best equipped to optimize maternal health during Fontan pregnancy and to facilitate safe delivery. The considerations for Fontan pregnancy management are shown in Figure 3.
Benjamin P. Frischhertz, MD; Adult Congenital Heart Disease, Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
Patients With Fontan Physiology
The major complications encountered in this case series in the peripartum period were hypoxemia, heart failure, and hemorrhage. The development of heart failure and cyanosis likely was associated with the cardiovascular stress of pregnancy, especially in the peripartum period. In the patients with normal cardiac physiology, the maternal cardiac output (CO) increases by 30% to 50%, driven by an increased preload from blood volume expansion in early gestation, followed by an increase in heart rate. This increase in CO peaks at approximately 24 weeks of estimated gestational age.
The patients with Fontan physiology have a relatively fixed CO, with limited capacity to accommodate the increased blood volume associated with pregnancy.
Pregnancy-induced anemia typically is mild and well-tolerated; however, in this patient population, it can further impair the oxygen-carrying capacity and contribute to the development of heart failure.
These normal physiologic changes of pregnancy may contribute to an increased risk of cardiovascular morbidity accompanying contemporary-era Fontan pregnancies in the setting of pulmonary blood flow without a subpulmonic pumping chamber.
In the authors’ case series, systemic embolism was higher than other reports (15% v 1.7%), as was heart failure (8% v 3.9%), though comparisons were difficult due to the small sample size.
Jennifer Thompson, MD; Obstetrics and Gynecology, Vanderbilt University Medical Center, Nashville, TN, USA
Anticoagulation in Pregnancy and Postpartum Hemorrhage
The patients with Fontan palliation often are prescribed chronic anticoagulation due to an increased risk of thrombotic complications and/or paradoxical embolism either related to arrhythmias, residual anatomic stumps, or fenestrations.
Management of pregnancy in patients with complex congenital heart disease: A scientific statement for healthcare professionals from the American Heart Association.
In order to ameliorate the risk of maternal hemorrhage, the patients on chronic warfarin therapy should be converted to low-molecular-weight heparin (LMWH) throughout the pregnancy (and definitively by the third trimester for rare uses, such as doses <5 mg among mechanical valve patients).
Interestingly, only 33% of parturients with postpartum hemorrhage were on chronic anticoagulation therapy, which underscored the underlying placental insufficiency associated with Fontan physiology. Larger studies are warranted to determine whether systemic anticoagulation is associated with an increased risk of hemorrhage.
Postpartum hemorrhage, defined by >1,000 mL blood loss during and within 24 hours of a C-section, was the most common peripartum obstetric complication seen in this case series, consistent with a prior study.
The patients with Fontan physiology are at increased risk for postpartum hemorrhage for a multitude of reasons, including liver dysfunction, elevated systemic venous pressure, decreased CO, thromboembolic disorders, and abnormal vascular malformations.
In this case series, maternal hemorrhage occurred secondary to placental abruption, subchorionic hemorrhage, and 1 case of placenta accreta that resulted in an emergency hysterectomy (Table 3). Most of the deliveries were performed by C-section, often urgent due to nonreassuring fetal status and/or placental pathology (Table 3). Forceps-assisted delivery was employed for all of the patients who delivered vaginally in order to avoid the Valsalva-induced reduction in preload.
Management of pregnancy in patients with complex congenital heart disease: A scientific statement for healthcare professionals from the American Heart Association.
Susan Eagle, MD; Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, USA
CO in Fontan Physiology and the Anesthetic Management of Fontan Parturients
Fontan physiology is sensitive to changes in preload, contractility, and afterload, all of which may be affected acutely by pregnancy and by the administration of anesthetic agents. Without a subpulmonic ventricle, adequate preload to the single ventricle in patients with Fontan physiology depends on the transpulmonary gradient and the transpulmonary resistance. The transpulmonary gradient is a pressure difference between the central venous pressure and the common atrial pressure, and, thus, is dependent on systemic venous pressure, pulmonary vascular resistance (PVR), and single ventricular function. The CO in patients with Fontan physiology can be altered significantly with perturbation in any of these factors.
Decreases in preload, such as during neuraxial blockade or the administration of anesthetic agents that reduce systemic vascular resistance (SVR), can dramatically affect CO and impair end-organ perfusion. Mechanical ventilation with excessive tidal volume or positive end-expiratory pressure increases intrathoracic pressure, which can reduce preload and increase PVR, thereby reducing CO. Similarly, volatile anesthetics, such as sevoflurane and isoflurane, reduce SVR and may have negative inotropic effects on the systemic ventricle.
During delivery, the anesthesiologist must be prepared for maternal hemorrhage in Fontan pregnancy, ensuring 2 large-bore peripheral IV catheters, fluid warming devices, and the availability of compatible blood products. The assessment of cardiac function with transthoracic echocardiography may be warranted, particularly during large-volume resuscitation and in patients with reduced systemic ventricular function. The filters placed on IV lines often inhibit fluid resuscitation and are not practical in the intraoperative setting. Thus, the anesthesiologist must thoroughly deair all IV access lines to prevent paradoxical air emboli (Fig 4).
Figure 4Anesthetic Considerations for Fontan Pregnancy.
Neuraxial anesthesia, including combined spinal-epidural or epidural was employed in nearly every patient in this study (Table 3). Anticoagulation was discontinued for 24 hours prior to neuraxial blockade, according to the American Society of Regional Anesthesia and Pain Medicine guidelines.
Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (Fourth Edition).
In the event prophylactic LMWH was received within 12 hours or therapeutic LMWH within 24 hours of an urgent C-section, these authors would follow the American Society of Regional Anesthesia and Pain Medicine guidelines and initiate general anesthesia instead of neuraxial blockade. In this cohort, the patients receiving LMWH who underwent an urgent C-section had enough time lapse to safely receive neuraxial blockade. All of the patients received between 300-to-500 mL of IV crystalloid bolus prior to the neuraxial anesthetic to offset the expected decrease in preload, while avoiding the risk of congestive heart failure from excessive volume loading. Although neuraxial blockade often causes sympatholytic-induced bradycardia and hypotension, heart rate and blood pressure were maintained within 20% of baseline after neuraxial blockade with the modest use of phenylephrine and ephedrine (Table 3), without the need for vasoactive infusions. The authors preferred a neuraxial blockade to reduce the risks of intubation and mechanical ventilation (which place the patient at higher risk for aspiration and can reduce CO by reductions in preload and increases in PVR).
Management of pregnancy in patients with complex congenital heart disease: A scientific statement for healthcare professionals from the American Heart Association.
The management of postpartum uterine atony may be complicated in patients with Fontan physiology due to the side effects of uterotonic agents, including a decrease in SVR, hypotension, and tachycardia.
Oxytocin is used commonly as a first-line uterotonic agent, and was the uterotonic of choice in this case series. However, the side effects include systemic vasodilation and pulmonary vasoconstriction, creating a potentially deleterious physiologic state for patients with Fontan physiology. These effects are more pronounced when given as a bolus dose or with a rapid infusion. However, with a standard infusion rate of 10 U/h, these cardiovascular side effects are less pronounced and likely safe for mindful use in patients with Fontan physiology.
Notably, significant hemodynamic changes were not encountered with the use of oxytocin in this series. The tocolytic methylergonovine (Methergine) can cause hypertension and vasoconstriction, whereas 15-Methyl prostaglandin F2-alpha may cause systemic and pulmonary hypertension and bronchospasm, thus potentially decreasing pulmonary blood flow and CO in the parturient with Fontan physiology.
Invasive blood pressure monitoring with an intraarterial catheter may be considered for the management of hemodynamic changes associated with anesthesia and/or postpartum hemorrhage in the parturients with Fontan physiology. Central venous catheters are not encouraged due to the risk of thrombosis or injury to the cavopulmonary anastomosis. If a central venous catheter is needed for inotropic support, these authors recommend the smallest size needed to achieve hemodynamic goals while avoiding thrombosis.
All of the patients in this series were managed by a multidisciplinary team, including cardiac anesthesiologists. In recent years, the authors have added a director of perioperative congenital cardiac anesthesiology, who is trained in both adult and pediatric cardiac anesthesiology, to consult on all patients with congenital heart disease by 23 weeks of estimated gestational age. Information about each patient is relayed to the adult cardiac anesthesiology division. This additional safeguard is particularly beneficial for parturients who present acutely with preterm labor, hemorrhage, or Fontan failure.
Expert Commentary #4
Angela Weingarten, MD, MSCI; Adult Congenital Heart Disease, Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
Postpartum Care
Multidisciplinary care is crucial for minimizing hospital length of stay while providing appropriate monitoring of the parturient with Fontan physiology in the postpartum period. The majority of patients were hospitalized between 3-to-9 days after delivery, whereas other pregnancies resulted in hospitalization for >5 weeks. Notably, in the patients with repeat pregnancies, the hospital length of stay increased after each delivery. One cause of prolonged hospitalization was hypoxemia. In the patients with a well-functioning Fontan, the oxygen saturation in the arterial blood should be ≥92%, with a small right-to-left shunt from venous blood returning from the coronary sinus into the common atria. Hypoxemia in this patient cohort may herald failing Fontan physiology, including systemic ventricular failure, pulmonary embolism, venovenous collaterals, and right-to-left shunting through a Fontan fenestration. Acute heart failure and hospital-acquired pneumonia were the etiologies of hypoxemia in the postpartum period, with a return to baseline prior to hospital discharge. It was observed that acute-to-chronic heart failure occurred in the parturient with preexisting depressed systolic function of the single ventricle and a higher ZAHARA score on presentation (Tables 1 and 3).
Cerebral vascular accidents from thromboembolic events also were a major source of morbidity in this cohort. The CVAs occurred in the patients both with and without chronic systemic anticoagulation therapy. However, given the propensity of thromboembolic events in patients with Fontan physiology and the resultant devastating effects, multidisciplinary planning of peripartum anticoagulation is of paramount importance.
Finally, although the authors did not encounter acute peripartum arrhythmias in this cohort, other analyses of Fontan pregnancies found that arrhythmias were among the most common cardiovascular adverse events (present in ∼8.4% of Fontan pregnancies).
Therefore, providers should consider the risks and benefits of telemetry monitoring based on local availability during Fontan pregnancy hospitalization. Figure 4 summarizes key considerations for the anesthesiologist managing a Fontan pregnancy.
Conclusions
Although contemporary-era management of high-risk pregnant patients with Fontan palliation can occur safely without peripartum mortality, there remains the risk of significant maternal and neonatal morbidity. In this case discussion, the authors outlined peripartum complications among a series of Fontan pregnancies at their center over a 20-year period, and reviewed multidisciplinary considerations for the peripartum management of the parturient with Fontan physiology. Specifically, these authors recommended the involvement of cardiac anesthesiologists from the antepartum through peripartum periods. Long-term follow-up of this unique patient population is warranted.
Limitations
There were inherent limitations to a single-center, retrospective study design related to incomplete data, unmeasured confounding variables, and generalizability. Additionally, the authors’ study's small case series size, although a substantial experience for any single center, was an inherent limitation. The cardiac phenotype was presented based on routine clinical follow-up, which was performed consistently by 2 adult congenital heart disease cardiologists, but lacked standardized noninvasive and invasive testing intervals and, thus, was selected as the most recent outpatient data immediately prior to and after pregnancy. Finally, the care of these complex patients was nuanced due to their unique anatomic and physiologic states, coupled with the significant stress of pregnancy. The authors’ case conference aimed to highlight peripartum complications and outline the key aspects of the multidisciplinary approach toward caring for these patients. However, their discussion was not comprehensive, and successful care for these patients requires both expertise and thoughtful, individualized planning that the authors’ case conference may risk oversimplifying (Table 4).
Table 4Cardiac and Extracardiac Complications
Cardiac
•
Arrhythmias: 45% of patients at 10 y
•
Heart failure: 70% of patients at 10 y
•
Fontan obstruction: tunnel, conduit, or branch PA stenosis
•
Ventricular dysfunction
•
Valvular disease
•
Pulmonary hypertension: lack of pulsatile blood flow leads to increased pulmonary vascular tone
•
Presence of shunts: fenestration, baffle leak, collaterals
Pulmonary
•
PAVMs: may cause cyanosis and volume overload from right-to-left shunt
•
Plastic bronchitis: bronchial casts leading to obstructive lung disease
Hepatorenal
•
FALD: manifests as cirrhosis, ascites, varices, hepatomegaly, elevated transaminases, altered drug metabolism
•
Fontan-associated kidney disease: present in up to 50% of adult patients
Gastrointestinal
•
PLE: loss of proteins through intestinal lumen, carries a high mortality rate
Hematologic
•
Anemia: present in up to 50% of patients
•
Polycythemia: may occur in presence of ongoing cyanosis
•
Thrombocytopenia: platelet dysfunction also common
•
Thromboembolic disease: 30% of patients have at least one thromboembolic event by 10 y
Redefining expectations of long-term survival after the Fontan procedure: Twenty-five years of follow-up from the entire population of Australia and New Zealand.
Rychik J, Atz AM, Celermajer DS, et al. Evaluation and management of the child and adult with Fontan circulation: A scientific statement from the American Heart Association [e-pub ahead of print[. Circulation. doi: 10.1161/cir.0000000000000696. Accessed May 1, 2022.
Management of pregnancy in patients with complex congenital heart disease: A scientific statement for healthcare professionals from the American Heart Association.
Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (Fourth Edition).
Research reported in this publication was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health under Award Number T32HL007411. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
All authors provided final approval of the submitted manuscript and agree to be accountable for all aspects of the work. Additional author contributions are as follows: D.E.C. was responsible for study conceptualization and design; data acquisition, interpretation, and analysis; drafting the article and all subsequent revisions; G.S., K.C., S.D., S.H., B.F., J.T., and A.J.W. were responsible for data interpretation; critical revisions; R.D.B. and C.J. were responsible for study design; data acquisition and interpretation; critical revisions; and S.E. was responsible for study conceptualization and design; data acquisition, interpretation, and analysis; critical revisions.
This invited editorial is related to: Ref.: Ms. No. JCVA-D-22-00216R2 Case series conference: Anesthetic management in parturients with Fontan physiology “If you have choices choose the best. If you have no choices do your best!” Nishan Panwar
Right-to-left shunting.
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