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Ann Thorac Surg 1996;62:461-462
© 1996 The Society of Thoracic Surgeons
DR FRANCISCO J. PUGA (Rochester, MN): This is a very excellent presentation and a very considerable experience on a difficult subject. I congratulate you for your excellent results. I have one question. Did I understand correctly that you propose interruption of any other source of pulmonary blood flow at the time of performance of the hemi-Fontan or bidirectional Glenn procedure? If that is the case, have you seen any patients in whom pulmonary arteriovenous fistulas have appeared? We have seen some of this in our experience, and we have also seen development of extensive systemic-to-pulmonary collaterals that may actually interfere with the performance of the Fontan procedure later on.
DR JACOBS: Yes, I think that is a very appropriate question. The interval between hemi-Fontan and completion Fontan operation for the majority of these patients is on the order of 12 months. We have not seen in this group of patients evidence of important intrapulmonary arteriovenous fistulas. There are a few outliers who, on the basis of social reasons or reasons of referral, are now 3 or 3
years out after the hemi-Fontan operation and awaiting reevaluation before completion, and I think we will have to look very critically to see if there is any evidence of arteriovenous fistula formation in that group.
DR CARLO MARCELLETTI (Rome, Italy): I enjoyed very much the presentation of such extensive experience. I would like to reinforce the observation that Dr Puga has made. Excluding hypoplastic left heart syndrome, for all other congenital anomalies we prefer to leave additional sources of pulmonary blood flow when performing the hemi-Fontan operation. This is because we have observed development of arteriovenous fistulas in patients with heterotaxy syndrome in whom we had done a bidirectional Glenn procedure.
I would also like to reiterate what you mentioned about sudden changes in geometry of the ventricle when performance of a cavopulmonary anastomosis abruptly decreases the pulmonary-to-systemic flow ratio to 1.0 or less, for example, after pulmonary artery banding of a univentricular heart. In such a condition we always avoid a one-stage Fontan operation and instead go through a first-stage Damus-Kaye-Stansel procedure and cavopulmonary anastomosis, followed later by total extracardiac cavopulmonary connection.
DR JACOBS: Doctor Marcelletti, I would agree completely with your latter comment. And part of the strategy in staging the Fontan operation is to eliminate any of those obstructions or hemodynamic burdens that could cause persistence of myocardial hypertrophy up to the time of the Fontan procedure. I therefore would agree that if one anticipates pulmonary artery-to-aortic anastomosis, it is very good to accomplish it at the time of the hemi-Fontan operation, as it was in 6 patients in this series with no mortality among that small group.
With regard to your first question, I think the development of arteriovenous fistulas in the lungs in heterotaxy syndrome patients after a Kawashima operation or total cavopulmonary connection is a fascinating quirk of nature. I am not certain whether the substrate is exactly the same as with the bidirectional cavopulmonary anastomosis or hemi-Fontan operation because we have seen in the heterotaxy group, as you described, very early development of arteriovenous fistulas, less than 6 months after total cavopulmonary anastomosis. I would only encourage you and the group perhaps not to look on this as an untreatable or irreversible problem because we now have experience in a small group of patients creating an intracardiac lateral tunnel or an extracardiac Marcelletti-type Fontan operation connecting the hepatic veins to the lung arteries, and at least in 2 of those patients at recatheterization we no longer see evidence of the arteriovenous fistulas in the lungs.
DR IVATURY M. RAO (Abu Dhabi, United Arab Emirate): I congratulate Dr Jacobs on a wonderful experience and presentation. I just have one small doubt about this concept of hemi-Fontan operation. When you have these big incisions in and near the superior vena caval–right atrial junction and put a patch at the mouth of the superior vena cava, what is the incidence of maintenance of sinus rhythm?
Also, does the patch of the superior vena cava mouth interfere with the growth of the superior vena caval–right atrial junction, when you go to do the Fontan operation?
DR JACOBS: I think those are two very important questions. I will answer the second first. The second question was, does the patch closure of the right atrial–superior vena caval junction interfere with growth of that opening? The incision that is made in the superior part of the atrium and carried on to the medial aspect of the right superior vena cava allows us to close the superior vena caval–right atrial junction with a patch considerably larger than the original size of the superior vena caval–right atrial junction. Doctor Van Praagh did an interesting morphologic study where he showed that in patients with a variety of heart malformations, the caliber of the opening of the superior vena cava into the heart was often as small as 60% of the caliber of the opening of the inferior vena cava into the heart. It is specifically in relation to that phenomenon that we routinely enlarge the opening of the superior vena cava into the heart.
As far as the impact of this strategy on rhythm, I think that this is a very important thing to investigate. We are presently in the process of analyzing retrospectively the impact of this staged approach on rhythm, both early and late after operation. I do not have the hard data. I would say anecdotally that the overwhelming majority of patients who come back for completion Fontan operation after a prior hemi-Fontan operation are in either a sinus rhythm or a rhythm that is initially interpreted as sinus rhythm but may in fact originate from another atrial pacemaker and is often a left atrial rhythm. I think what ultimate impact that is going to have remains to be determined.
DR EDWARD L. BOVE (Ann Arbor, MI): We recently reviewed our experience with 100 patients having hemi-Fontan procedures before age 6 months and would agree with you that young age was not a risk factor for mortality but it seemed to be one for morbidity. I wondered what comments you might make on postoperative morbidity in the very young patients from your experience. We noticed that some of these patients were fairly hypoxemic for the first few days and then seemed to get better.
When we looked at postoperative arrhythmias, it prompted us to change our technique, modifying the incision. It no longer crosses the cavoatrial junction but is limited to the base of the right atrium. Since then, all of the patients have been in sinus rhythm, which we think has been a benefit. Would you comment on that?
DR JACOBS: I think the latter is very encouraging if it is associated with consistent preservation of sinus rhythm. In terms of the very young patients, we are aware of the excellent results that you presented at the American Heart Association meeting where you showed that the saturation early postoperatively was lower in the very young patients, and I think a few of them experienced caval or pulmonary artery thrombosis. We have not seen that complication, although I would echo your observation that the initial arterial oxygen tension and systemic arterial saturation is generally lower in this group. That finding tends to persist for only the first 24 or 36 hours. By the time they leave the intensive care unit, they all wind up being about 84% saturated. So I think that the pulmonary vascular resistance probably behaves somewhat differently in the very young patients early postoperatively.
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Ann. Thorac. Surg. 1996 62: 456-461.
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