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Division of Cardiovascular-Thoracic Surgery, Children's Memorial Hospital, Feinberg School of Medicine, 2300 Children's Plaza, MC 22, Chicago, IL 60614
(Email: cbacker{at}childrensmemorial.org).
In 1995, we reported our results with the two-patch technique for complete atrioventricular (AV) septal defect from the Children's Memorial Hospital [1]. For a series that started in 1983, we believed that we had fairly good results with an operative mortality of 7%, reoperation for left AV valve insufficiency of 7%, and reoperation for left ventricular outflow tract (LVOT) obstruction of 4%. The series reported by Suzuki and colleagues [2] demonstrates that the results with the two-patch technique have continued to improve since 1995. Operative mortality in this University of Michigan series is only 2%. The age at time of repair decreased from a median age of 8 months in our series to 4.8 months in this current series. In fact, one of the reasons for this improvement in outcomes is the younger age at the time of repair. This decreases the complications caused by postoperative pulmonary hypertension and progressive dilatation of the AV valve with resultant AV valve insufficiency.
The two outcome measures that do not seem to have changed for the past 10 years are the incidence of reoperation on the left AV valve and reoperation for LVOT obstruction. The incidence of left AV valve reoperation was 7% in our series from 1995 and 6.5% in this more recent series. The incidence of reoperation for LVOT obstruction was 4% in our series and 5% in the University of Michigan series. In fact, Suzuki and colleagues [2] note, "Despite this remarkable decrease in postoperative mortality, postoperative morbidity remains significant, the most prevalent being short- and long-term AV valve dysfunction, and late LVOT obstruction."
The question I believe congenital heart surgeons need to ask is whether or not we can improve on these two outcome measures. Is this problem with postoperative AV valve insufficiency and LVOT obstruction inherent in complete AV septal defects, or is it surmountable with improved or different surgical techniques?
I would submit that there is a technique that can improve on both the problems of left AV valve insufficiency and LVOT obstruction and that is the modified single-patch technique independently proposed by Wilcox and colleagues [3] and Nicholson, Nunn, and colleagues [4]. This technique eliminates the ventricular septal defect (VSD) patch and entails direct closure of the ventricular component of the defect by sandwiching the AV valve tissue between the crest of the ventricular septum and the pericardial patch used to close the atrial component. We began transitioning from the two-patch technique to the modified single-patch technique in 2001, and we have converted to its essentially universal use in 2006, a 5-year transition [5].
In the current series from the University of Michigan, 18 patients had repairs done using the modified single-patch technique. The results in this group were not separated out from the total group. However, in the comments section the authors note, "While the results were uniformly positive, the study design and small numbers of patients undergoing this technique (modified single-patch) prevents comment on the applicability of the technique in all patients, regardless of VSD size."
For an invited article in the Seminars of Thoracic and Cardiovascular Surgery [6], we recently did a comparison of selected series of AV septal defect repairs. The operative mortality of the modified single-patch technique in 200 patients was 2%, with an incidence of left AV valve reoperation of only 2%. This was markedly different than the incidence of left AV valve reoperation with the two-patch technique (7% of 889 patients) or the classic one-patch technique (9.7% of 350 patients). I believe the modified single-patch technique may be the technical answer to improving left AV valve function for which we have been searching. By operating on younger patients (3 to 4 months of age), by not dividing the AV valve leaflets, and by not placing a patch for the VSD, we may be able to decrease the frequency of reoperations on the left AV valve.
The other outcome measure that does not seem to have improved is late left ventricular outflow tract (LVOT) obstruction. One of the reasons given by surgeons hesitant to use the modified single-patch technique is that "without a VSD patch these patients will have obstruction because of crowding in the LVOT." However, if one looks at the data in actuality the converse may be true. In this current University of Michigan series (mostly two-patch technique), the incidence of LVOT obstruction requiring reoperation was 5%. In the collected series of 200 modified single-patch patients, some patients operated on by Nunn now out for 10 to 15 years (n = 26), there were no patients who required a reoperation for LVOT obstruction [7]. Although it is counterintuitive, the synthetic patch placed in a two-patch technique may actually promote fibrosis that leads to obstruction in the left ventricular outflow tract because of increased rigidity, turbulence of blood flow, and the presence of a foreign body in the left ventricular outlet.
The University of Michigan surgeons are to be congratulated for their outstanding results with AV septal defect, particularly the excellent results in very young infants with significant congestive heart failure. Although this series from the University of Michigan confirms that excellent results can be obtained with the two-patch technique, there may be an opportunity for surgeons to improve the natural history of patients with complete AV septal defect by changing to the modified single-patch technique. Only further long-term follow-up of both procedures, such as the excellent review provided by Suzuki and colleagues [2], will determine whether we can indeed reduce the incidence of reoperations for left AV valve insufficiency and LVOT obstruction in patients with complete AV septal defect.
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