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From the Department of Anesthesiology, Perioperative and Pain Medicine, Children’s Hospital Boston, Harvard Medical School, Boston, Massachusetts.
Address correspondence to Craig D. McClain, MD, Department of Anesthesiology, Perioperative and Pain Medicine, Children’s Hospital, 300 Longwood Avenue, Bader 3, Boston, MA 02115. Address e-mail to craig.mcclain{at}tch.harvard.edu.
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CASE REPORT |
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Procedure 1: Cholecystectomy
Before this procedure, the patient had no physical signs of impaired cardiac output, hypoxemia, or venous congestion. Preoperative electrocardiogram demonstrated sinus rhythm with an abnormal P wave axis consistent with dextrocardia. Her preoperative echocardiogram demonstrated qualitatively good systemic ventricular function, patent Fontan pathways, no intraatrial shunting, and mild atrioventricular valve regurgitation.
The patient had an IV line placed preoperatively for hydration and was sedated with midazolam and fentanyl. Anesthesia was induced with etomidate, sufentanil, and pancuronium. A narcotic-based anesthetic was chosen to provide maximal cardiac stability throughout the case. Tracheal intubation and radial arterial line placement occurred uneventfully. After anesthetic induction and line placement, but before incision, the patient developed atrial flutter. She became mildly hypotensive and was given IV fluids, adenosine (3x), and phenylephrine without clinical improvement. She then immediately underwent D/C cardioversion at 100 J with subsequent conversion back to sinus rhythm and a return to hemodynamic stability.
Anesthetic maintenance consisted of intermittent midazolam boluses and a sufentanil infusion. The patient tolerated incision, pneumoperitoneum, and surgery. Intraabdominal pressures were maintained at <10 cm H2O. Positive pressure ventilation was used with peak airway pressures of 24 mm Hg and minute ventilation adjusted to keep end-tidal CO2 at 33–36 mm Hg. She did not develop arterial oxygen desaturation or clinical signs of reduced cardiac output. Intraoperative transesophageal echocardiography revealed qualitatively good systemic ventricular function and filling that was unchanged throughout the procedure, despite the various surgical maneuvers. Urine output was adequate throughout the procedure. The patient remained stable throughout the procedure and required no unexpected alterations to her anesthetic regimen. Her trachea was extubated without incident upon completion of the procedure, and she was admitted to the hospital postoperatively for continued monitoring of her cardiac rhythm. She remained stable and was discharged home on postoperative day 2.
Procedure 2: Cauterization of Endometriosis with Lysis of Adhesions
Since the cholecystectomy, the patient had undergone atrial pacemaker placement secondary to sinus node dysfunction. Otherwise, her physical status and preoperative evaluation were essentially unchanged from that described previously. Before the induction of anesthesia, her pacemaker mode was switched to asynchronous atrial pacing at a modestly increased rate above baseline.
An IV infusion was started, midazolam given for sedation, and albumin given for intravascular volume expansion. Anesthesia was induced using etomidate, remifentanil, and vecuronium. The trachea was intubated, a radial arterial catheter was placed, and she was positioned without incident. Anesthetic maintenance consisted of varying concentrations of sevoflurane in air/oxygen, remifentanil, and vecuronium. She tolerated incision, Trendelenburg positioning, and CO2 insufflation without incident. Intraabdominal pressures were kept <10 cm H2O, which did not seem to affect oxygenation, ventilation, or cardiac output (e.g., pulse oximetry, end-tidal CO2, arterial blood pressure). As in her first laparoscopic procedure, she remained stable throughout, and did not require any unexpected changes to her anesthetic regimen. The surgery concluded uneventfully. After reversal of neuromuscular blockade, the trachea was extubated and she was taken to the recovery room. She continued to do well and was discharged home the following day.
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DISCUSSION |
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In Fontan physiology, systemic venous blood is directed passively into the pulmonary circulation. Oxygenated blood then drains into a common atrium and thence into the single ventricle that perfuses the systemic circulation. The difference between central venous pressure and systemic ventricular end-diastolic pressure (termed the "transpulmonary gradient") is the primary force promoting pulmonary blood flow and, more importantly, cardiac output. Therefore, determinants of the efficacy of the Fontan circulation include systemic venous pressure and volume, pulmonary vascular anatomy, pulmonary vascular resistance, atrioventricular valve function, cardiac rhythm, and the function of the systemic ventricle. Perturbation of these factors in Fontan patients, alone or in combination, may compromise systemic cardiac output. Perioperative management in Fontan patients includes maintenance of adequate intravascular volume (preload), appropriate ventilation to maintain adequate lung volumes and gas exchange, and minimizing factors that reduce systemic ventricular function. Because significant venoconstriction (i.e., maximal or near maximal preload augmentation) may be present at baseline, maneuvers that result in venodilation may have detrimental effects on the hemodynamic status of the patient. We routinely administer intravascular fluids to patients with Fontan physiology before any general anesthetic. This practice may be even more important in such patients who are to undergo laparoscopic procedures because of added concerns of the pneumoperitoneum. End-organ dysfunction may result from several factors, including chronically increased venous pressure and limited cardiac output (12). The risk of perioperative thromboembolic events may be increased in Fontan patients; potential reasons include alterations in pro- and anticoagulant factors as well as abnormal Fontan anatomy and "sluggish" circulation (13).
Physiologic changes produced by CO2 insufflation and positioning for laparoscopy may be at odds with Fontan physiology (1–7). Increased intraabdominal pressure from pneumoperitoneum could lead to a significant decrease in cardiac index (4,6,7). Several studies have examined the impact of different intraabdominal pressures on various measurements of cardiac performance in healthy patients with anatomically normal hearts (6,14–17). These reports show that insufflation pressures of <8–12 cm H2O did not decrease cardiac output. A decrease in cardiac output was seen only in pressures more than 15–20 cm H2O. In fact, at lower intraabdominal pressures, cardiac output increased. However, insufflation of the abdomen, even at low pressures, was also associated with increases in intrathoracic pressure (ITP), pulmonary capillary wedge pressure, and mean airway pressure. All these measurements were increased as intraabdominal pressure was increased. Further, increases of these three pressures (ITP, pulmonary capillary wedge pressure, mean airway pressure) may be detrimental to a patient with Fontan physiology. There are no such studies in patients with Fontan physiology.
Hypercarbia could result from CO2 absorption as well as impaired ventilation (due to abdominal distention); increased amounts of positive pressure could further increase pulmonary vascular resistance and impair venous return by increasing ITP (2,3). Additionally, there are numerous reports of CO2 emboli resulting from insufflation (18–20). Consequences of CO2 embolus and resultant limitation of pulmonary blood flow and cardiac output are likely to be more severe in patients whose pulmonary blood flow is passive. The presence of a patent fenestration in the Fontan pathway (which is used to preserve systemic ventricular filling and output) would add the risk of paradoxical CO2 embolism to the coronary and/or cerebral circulations.
A small group of infants with status post-Stage I palliation of hypolastic left heart syndrome who had undergone successful laparoscopic Nissen fundoplication was recently described (21). The present case report suggests that laparoscopic abdominal surgery is possible in patients with well-compensated Fontan physiology. The possibility of pulmonary and paradoxical CO2 embolism, and their potential severity in this patient population, should be considered. Minimizing insufflation pressure and duration in this group of patients would seem to be especially important, as would ensuring adequate ventilation and intravascular volume, avoiding techniques that reduce cardiac contractility, and maintaining willingness to convert to an open procedure in the setting of impaired ventilation or cardiac output.
The complex and variable nature of patients with repaired congenital heart disease requires close cooperation and involvement of practitioners with expertise in the perioperative assessment and management of pediatric and adult congenital heart disease. A recent cardiology evaluation before administering a general anesthetic to such patients is important. Useful preoperative data may include an echocardiogram and/or catheterization to delineate degree of function, valvular competence, and shunting. Preoperative electrocardiogram is important to evaluate for possible rhythm disturbances. The individual anesthetic agents chosen are probably important only in respect to understanding the physiology of the given lesion and the consequent effects of those drugs on that altered physiology.
Significant sequelae, many specific to the type of lesion and its repair(s), can be expected in a sizable number of patients with "corrected" congenital heart disease (22). It will become increasingly common to encounter surgical situations similar to those reported here. There are currently no published trials risks stratifying such patients for laparoscopic surgery. Further study is necessary to define appropriate inclusion and exclusion criteria in potential candidates for laparoscopic and other procedures.
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Footnotes |
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Supported by the Milton Alper Clinical Research Fellowship and the Department of Anesthesiology, Perioperative and Pain Medicine, Children’s Hospital, Boston.
This work was presented in part at the 2005 Winter Meeting of the Society for Pediatric Anesthesia, Miami Beach, FL.
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This article has been cited by other articles:
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  S. Nayak and P.D. Booker The Fontan circulation CEACCP, February 1, 2008; 8(1): 26 - 30. [Full Text] [PDF]
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 D. Naydenov, S. Khan, M. S. Plisco, and C. Veremakis PATIENT WITH SEPTIC SHOCK AND FONTAN CIRCULATION Chest Meeting Abstracts, October 1, 2007; 132(4): 674 - 674. [Abstract] [PDF]
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