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J Thorac Cardiovasc Surg 1997;114:867
© 1997 Mosby, Inc.

LETTERS TO THE EDITOR

Inhaled nitric oxide after Glenn and Fontan procedures

Division of Pediatric Cardiology
University of Utah
Primary Children's Medical Center
100 North Medical Dr.
Salt Lake City, UT 84113

To the Editor:

I read with interest the article by Gamillscheg and associates ¹ concerning the use of inhaled nitric oxide in patients with high systemic venous pressures after a bidirectional Glenn shunt or modified Fontan procedure. When inhaled, nitric oxide is a selective pulmonary vasodilator in many patients with increased pulmonary vascular resistance. Thus nitric oxide may potentially assist patients with right heart failure after surgical palliation or repair. The authors correctly state that "even a small reactive increase of PVR [pulmonary vascular resistance] may cause deleterious systemic venous hypertension associated with resistant low cardiac output syndrome" in this subset of patients. However, their study does not provide any evidence that inhaled nitric oxide improved the immediate or long-term outcome of their patients.

Patients were treated with inhaled nitric oxide if the pulmonary pressure exceeded 20 mm Hg or the transpulmonary pressure gradient exceeded 10 mm Hg. There were no controls to determine whether these elevated pressures may have spontaneously improved without inhaled nitric oxide therapy. Further, the authors did not determine whether patients had significant pulmonary endothelial dysfunction at the onset of therapy. After 12 to 18 hours, therapy was abruptly withdrawn for 5 minutes and hemodynamic and oxygenation measurements were repeated. The authors used these data to calculate significant "improvements" in pulmonary pressure, transpulmonary pressure gradient, and oxygenation. Unfortunately, the acute changes after nitric oxide withdrawal may have simply resulted from the suppression of endogenous nitric oxide production by inhalation therapy. ²

Goldman and associates ³ have also reported a favorable hemodynamic effect of inhaled nitric oxide in patients after the fenestrated Fontan procedure. Unfortunately, they also had no controls and 50% of their patients with an oxygen saturation less than 85% subsequently died. Nonetheless, they recommend that nitric oxide be used after a fenestrated Fontan procedure if the oxygen saturation is less than 85% and/or the transpulmonary gradient exceeds 12 mm Hg. Perhaps appropriate patient selection may be a more effective alternative than inhaled nitric oxide in the palliation of functional single ventricle.

In my opinion, the beneficial effects of inhaled nitric oxide in patients with postoperative pulmonary hypertension have been overstated and not adequately documented by even small controlled studies. The reports of Gamillscheg, ¹ Goldman, ³ and their associates underscore the need for carefully designed studies in determining the safety and efficacy of inhaled nitric oxide.

12/8/84443

References

1. Gamillscheg A, Zobel G, Urlesberger B, Berger J, Dacar D, Stein JI, et al. Inhaled nitric oxide in patients with critical pulmonary perfusion after Fontan-type procedures and bidirectional Glenn anastomosis. J Thorac Cardiovasc Surg 1997;113:435-42. [Abstract/Free Full Text]
   
2. Buga GM, Griscavage JM, Rogers NE, Ignarro LJ. Negative feedback regulation of endothelial cell function by nitric oxide. Circ Res 1993;73:808-12. [Abstract/Free Full Text]
   
3. Goldman AP, Delius RE, Deanfield JE, et al. Pharmacological control of pulmonary blood flow with inhaled nitric oxide after the fenestrated Fontan operation. Circulation 1996;94(Suppl):II44-8.
   

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Ronald Day Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Day, R. Search for Related Content PubMed PubMed Citation Articles by Day, R.