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Courtney A. Hardy, MD
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Mark Twite, MD, BCh
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Stuart R. Hall, MD
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President's Message

Letter from the Editor

An Update on the Fontan Operation: Morbidity, Mortality and Late Complications

An Interesting Case: A Case of an  Unexpected Airway Difficulty in the Cardiac Operating Room

Thanks to Our 2011 Exhibitors

LITERATURE REVIEW

Systematic Review: Benefits and Harms of In-Hospital Use of Recombinant Factor VIIa for Off-Label Indications

 

 

An Update on the Fontan Operation: Morbidity, Mortality and Late Complications

By Lizabeth D. Martin, MD; Denise C. Joffe, MD; and Michael Richards, BM, MRCP, FRCA
Seattle Children’s Hospital

I. Introduction

The Fontan procedure, first developed by Fontan in 1971, is a palliative procedure for patients with functional univentricular physiology. Over the past 40 years, perioperative mortality has decreased substantially as surgical technique and perioperative care has improved. Long term outcomes and late complications are now more apparent as patients live longer; however several recent publications highlighting Fontan “palliation” have emphasized there is still progress to be made in the long term management of these patients.

II. Revision of Fontan Anatomy and Physiology

The incidence of univentricular physiology is thought to be 0.5-5 per 10,000 live births. There are many congenital cardiac anomalies that are palliated with multistage repair and ultimately the Fontan operation. Anderson whilst looking at outcomes after Fontan palliation reported the underlying anatomic diagnosis in 546 Fontan patients, which were most commonly tricuspid atresia (22%), hypoplastic left heart syndrome (21%), and double inlet left ventricle (15%).

There are variations in timing and type of preceding operations; however most patients have Fontan operation by 2-4 years. Fontan anatomy is characterized by flow of deoxygenated from the superior and inferior vena cave directly into the pulmonary vascular system. Blood flows passively through the lungs, into a common atrium, and through the atrioventricular valve to the systemic ventricle (morphologically right or left). A fenestration can be placed to relieve elevated venous pressures and augment cardiac output by shunting blood directly to the atrium. This can be useful in the post-operative period, when pulmonary vascular resistance may be high and cardiac output may be decreased after cardiopulmonary bypass.

There are several technical aspects of the Fontan procedure that have evolved over the past 40 years, perhaps the most worthy of mention is the evolution of the systemic venous to pulmonary connection. Classic or Atriopulmonary Fontan, the predominant technique until the late 1980s, involved anastomosis of the right atrium directly to the pulmonary artery and most adult patients older than 25 yrs have this anatomy. The disadvantage of this technique was the development of right atrial hypertension, leading to atrial stretch, dilation, arrhythmias and thrombus formation.

The Lateral Tunnel Fontan was introduced in the late 1980’s and involved baffling the systemic venous flow within the atrium in the hope of producing more streamlined blood flow and less atrial dilation. The extracardiac conduit technique was developed in the 1990’s, and has come into common practice in the past 10 years. This technique has all the advantages of the Lateral Tunnel with less atrial manipulation and fewer suture lines, however, placement of the fenestration often requires using cardioplegia. The combined extracardiac and intracardiac Fontan may address some of these deficiencies, as the intracardiac component allows for the placement of a fenestration and the extracardiac component limits the number of suture lines.

Optimal Fontan physiology includes central venous pressure (CVP) of 10-15mmHg (although most Fontan patients have CVP >12), pulmonary artery pressure of 10-15mmHg, and left atrial (LA) pressure of 5-10 mmHg. The pressure differential between the CVP and the LA, the “transpulmonary gradient,” is of paramount importance: this pressure differential is a major determinant of pulmonary blood flow and hence has a direct impact on cardiac output.

III. Epidemiology

Over recent decades there has been a significant improvement in perioperative mortality of Fontan patients. Khairy et al studied outcomes in 261 Fontan patients from 1973-1991, and reported 37% mortality before 1982, with an improvement to 16% between 1982 and 1989, and then 1.9% after 1990. Earing et al reviewed 225 double inlet left ventricle Fontan patients between 1974 and 2001 and described 13% perioperative mortality before 1988, and 3% thereafter. Khairy reported freedom from death or transplantation at 15, 20 and 25 years of 87%, 83% and 70% in patients who survived the perioperative period. In the Earing cohort, survival at 15 and 20 years was 73% and 69%. Earing also reported an improvement in 10 year survival to 89% within a post-1989 subgroup, demonstrating improvement from 80% 10 year survival prior to 1989.

Several studies suggest that functional limitations may adversely affect quality of life after the Fontan procedure. Anderson et al reported decreased exercise capacity in 546 patients, who had on average a peak oxygen consumption of 65% of predicted 8 years post Fontan.5 Van den Bosh et al surveyed late survivors who self-reported lower physical functioning, mental health, general health perception, only 65% of whom were employed. McCrindle et al surveyed 537 parents of Fontan patients who reported attention disorders, learning disabilities, and behavior problems (46%, 43%, 23%).

IV. Late Complications

There are numerous late multisystem complications associated with the Fontan procedure which have important anesthetic implications.

Cardiovascular complications include arrhythmias, heart failure and thromboembolism. Most outcome studies report a high incidence of atrial arrhythmias; with some groups suggesting only 19% of patients being arrhythmia free at 20 years, and up to 1/3 of late deaths were attributed to sudden cardiac death.5, 9 Although most patients have a relatively preserved ejection fraction (~70%), diastolic dysfunction is common (72%).5 Thromboembolism can be a catastrophic complication and occurs in 8-25% of patients; however systemic anticoagulation is controversial and not uniformly utilised.4, 9, 10

Plastic Bronchitis is a rare but serious complication characterized by mucinous acellular bronchial cast formation and airway obstruction with an associated mortality of up to 50%. The pathophysiology is thought to be related to injury to the bronchial epithelium and surgical damage of mediastinal lymphatic drainage. Various treatment modalities have been reported without reliable success: bronchoscopy and mechanical cast removal, t-PA, N-Acetylcysteine, CVP reduction, thoracic duct ligation, and improvement with improved ventricular function. , Other pulmonary complications include persistent hypoxia due to shunting through the fenestration, pulmonary edema (due to ventricular failure and AV valve dysfunction), persistent anatomical abnormalities, trans pulmonary flow obstruction and collateral formation.4

Protein Losing Enteropathy is present in 3-15% of Fontan patients, and develops on average 2-3 years after completion of the Fontan circuit. It is characterized by hypoalbuminemia, intestinal protein loss, edema, ascites, and immune deficiency. The underlying pathophysiology has not been clearly delineated, but chronic venous hypertension, low cardiac output and inflammation may all play a role. Mortality is reported to be as high as 30% at 2 years and 50% at 5 years. Liver disease is also common, and is thought to correlate with low cardiac output and elevated CVP. Over 50% of patients go on to develop hepatomegaly and/or cirrhosis. Despite these abnormalities, most have a relatively preserved albumin and INR.

V. Anesthetic Goals and Considerations

Preoperative evaluation should include review of recent cardiology visits, assessment of functional status, recognition of late complications and optimization of pulmonary pathology when possible. Ensuring normal preload in the peri-induction period, particularly in the setting of prolonged fasting times or comorbid dehydration is prudent.

Additional management involves manipulation of physiologic parameters to optimize the transpulmonary gradient and cardiac output, with emphasis on maintaining adequate preload, lowering pulmonary vascular resistance to preserve pulmonary flow, maintaining sinus rhythm and minimizing myocardial depression. Spontaneous ventilation will enhance venous return and pulmonary blood flow, but benefits must be carefully balanced with likelihood of hypercarbia, hypoxia and atelectasis. If necessary, the principals for mechanical ventilation emphasize minimizing positive pressure and the time over which it is delivered to maximize passive pulmonary blood flow. Peak pressure <20cmH20, minimal positive end-expiratory pressure, low respiratory rate (< 20) and short inspiratory time are guidelines that have been suggested.

VI. Future

As Fontan patients survive longer, it has become clear that there are limitations to the currently available palliative strategies. Randomized clinical trials are investigating possible medical modalities such as sildenafil which may improve ventricular function and optimize oxygen consumption in Fontan patients by reducing central venous pressures and augmenting cardiac output.2 Ventricular assist devices are another area of exciting research, and may offer further options for this patient population in the future.

VII. References

  1. Fontan F, Baudet E. Surgical repair of tricuspid atresia. Thorax 1971;26:240-248.
  2. Rychik J. Forty Years of the Fontan: A failed strategy. Ped Cardiac Surg Ann 2010; 96-100
  3. Gersony W. Fontan Operation after 3 Decades: what have we learned. Circulation 2008;117:13-15.
  4. Khairy P, Poirier N, Mercier LA. Univentricular Heart. Circulation 2007;115:800-12.
  5. Anderson PA, Sleeper LA, Mahony L et al. Contemporary Outcomes after the Fontan procedure: a Pediatric Heart Network multicenter study. J Am Col Cardiology 2008;52:85-98.
  6. Jonas R. The Intra/Extracardiac Conduit Fenestrated Fontan. Pediatric Card Surg Ann 2011;14:11-18.
  7. Jonas R. Comprehensive Surgical Management of Congenital Heart Disease. London UK: Hodder Publishing. 2004.
  8. Khairy P, Fernandes SM, Mayer JE. Long-term survival, modes of death and predictors of mortality with Fontan. Circulation 2008;117:85-92.
  9. Earing MG, Cetta F, Driscoll DJ, et al. Long-term results of the Fontan for DILV. Am J Card 2005;96:291-98.
  10. Van den Bosch et al. Long-term outcomes and quality of life in adult after Fontan. Am J Card. 2004:93:1141-5.
  11. McCrindle BW, Williams RV, Mitchell PD, et al. Relationship of patient and medical characteristics to health status in children and adolescents after Fontan. Circulation. 2006 113:1123-29.
  12. Tzifa A, Robards M, Simpson JM. Plastic Bronchitis; a serious complication of the Fontan operation. Int J Cardiology 2005;101(3):513-4.
  13. McMahon et al. The bronchial cast syndrome after Fontan procedure. Cardio I Young. 2001;11:345-51.
  14. Goo HW, Jhang WK, Seo DM et al. CT findings of plastic bronchitis after Fontan. Ped Rad 2008;38(9):989-93.
  15. Magee et al. Systemic venous collateral develop after the bidirectional cavopulmonary anastomosis. J Am Col Cardiology 1998;32:502-8.
  16. Feldt RH, Driscoll DJ, Offord KP. Protein-losing enteropathy after the Fontan operation. J Thorac Cardiovasc Surg. 1996;112:672-680.
  17. Mertens L, Hagler DJ, Sauer U, Somerville J, Gewillig M. Protein-losing enteropathy after the Fontan operation an international multicenter study. J Thorac Cardiovasc Surg. 1998;115:1063-1073.
  18. Rychik. Protein-Losing Enteropathy after Fontan operation. Congenital Heart Disease. 2007: 2:288-300.
  19. Kiesewetter CH, Sheron N, Vettukattill JJ, et al. Hepatic changes in the failing Fontan circulation. Heart 2007;93:579-84.
  20. Cammposilvan S, Milanesi O, Stellin G, et al. Liver and cardiac Function in the long term after Fontan. Ann Thor Surg 2008;86:177-82.
  21. Leyvi G, Wasnick JD. Single-Ventricle Patient: Pathophysiology and Anesthetic Management. J Cardio and Vasc Anesthesia 2010; 24(1):121-30.
  22. Baily PD, Jober DR. The Fontan Patient. Anesthesiology Clin 2009:285-300.
  23. Rodefeld MD, Frankel SH, Giridharan GA. Cavopulmonary Assist: (Em)powering the Univentricular Fontan Circulation. Pediatric Cardiac Surg Ann 2001;14:45-54.

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