Ann Thorac Surg 2006;81:234-235
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
Invited commentary
Michael H. Hines, MD
Department of Cardiothoracic Surgery, Wake Forest University School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157-1096
(Email: mhines{at}wfubmc.edu).
Since Dr Robert Gross performed the first surgical closure of a patent ductus arteriosus (PDA) in 1938, tens of thousands of operations have been performed. During these 67 years, tremendous advances have occurred in the field of neonatology, so that it is now commonplace to find 24-week gestation infants in a typical neonatal intensive care unit, commonly with a patent ductus. Unlike the term infant with a large PDA and resultant congestive heart failure, these tiny infants frequently have associated premature lung disease and elevated pulmonary artery pressures. Neonatologists, pediatric cardiologists, and cardiac surgeons now find themselves in a quandary of applying historical data from healthy infants and children to a population of patients with an entirely different set of issues.
In this article, our French colleagues [1] have nicely demonstrated that there is no advantage to delaying surgical closure after pharmacologic failure in premature infants in whom the PDA is documented to be hemodynamically significant. In fact their data suggests an advantage to earlier closure to allow earlier initiation of enteral nutrition. This is an important step in defining management strategies for this group of patients. However it is important to note that the entire series of patients had exclusively left to right shunting, and this rationale of early closure does not necessarily apply to all premature infants with PDAs.
There is a spectrum of patients ranging from those who clearly benefit from ductal closure (as the authors in this article have described) to those who do very poorly after closure because of pre-existing pulmonary hypertension and the subsequent development of right ventricular failure. Within the center of the spectrum lies a group of preemies for whom we have even less data. Many of these infants have echocardiographic and clinical evidence of bidirectional shunting or intermittent right to left shunting associated with the pulmonary hypertension of premature lung disease, or transiently associated with sepsis. Closure of the PDA in these infants removes the potential pop-off effect preventing right ventricular failure during transient elevation of the pulmonary vascular resistance. Yet failure to treat the PDA may contribute to progression of the lung disease and worsening pulmonary hypertension. There is currently little to no data supporting any particular management strategy for these difficult infants. Therefore we must rely on common sense and clinical judgment to guide us. At our institution we do not attempt to address PDAs in the presence of significant right to left shunting. Repeated echocardiographic evaluations on various levels of FiO2 can often help determine the reactivity of the pulmonary vascular bed and the contribution of primary pulmonary disease to any observed hypoxemia. With documented response to O2, we have usually proceeded with ductal closure and maintained tighter postoperative ventilatory management to prevent respiratory acidosis, along with liberalizing the utilization of oxygen therapy and nitric oxide. This relatively conservative approach has minimized our incidence of postoperative right ventricular failure that others have seen more commonly. Clearly we need to continue to investigate these issues and develop guidelines for these most complex patients.
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References
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- Jaillard S, Larrue B, Rakza T, Magnenant E, Warembourg H, Storme L. Consequences of delayed surgical closure of patent ductus arteriosus in very premature infants Ann Thorac Surg 2006;81:231-235.[Abstract/Free Full Text]
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