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Click here to read this article as a CME activity
Division of Cardiovascular Surgery, Mayo Clinic and Foundation, Rochester, Minnesota
Accepted for publication February 13, 2009.
* Address correspondence to Dr Burkhart, Division of Cardiovascular Surgery, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905 (Email: burkhart.harold{at}mayo.edu).
Presented at the Fifty-fifth Annual Meeting of the Southern Thoracic Surgical Association, Austin, TX, Nov 5–8, 2008.
| PEDIATRIC CARDIAC SURGERY:
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Abstract |
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Methods: Between 1972 and 2007, 50 patients (26 male) underwent reoperation at our institution after initial repair of CAVSD (median interval, 15 months; range, 3 days to 29 years). Median age at first reoperation was 4.5 years (range, 53 days to 38 years). Indications for first reoperation included left atrioventricular valve (LAVV) regurgitation in 41 patients, subaortic stenosis in 5, and LAVV stenosis, residual atrial septal defect (ASD), pulmonary artery (PA) stenosis, and aortic coarctation in 1 each.
Results: The first reoperation included LAVV repair in 21 patients and replacement in 21, modified Konno procedure in 3, septal myectomy in 2, and PA reconstruction, coarctation repair, and ASD re-repair in 1 each. After LAVV repair (n = 21) 5 patients required a second reoperation, and after LAVV replacement (n = 21) 6 patients required a second reoperation. Overall freedom from further reoperation after the first reoperation was 63%, 48%, and 42% at 5, 10, and 15 years, respectively. There were 2 early deaths (4%) after first reoperation, and none after subsequent reoperations. During late follow-up (median 10.7 years, maximum 30 years), actuarial overall survival was 91%, 91%, and 86% at 5, 10, and 15 years, respectively.
Conclusions: The most common indication for reoperation after CAVSD repair is LAVV regurgitation. LAVV re-repair offers good durability, and LAVV replacement does not preclude additional reoperations. Long-term survival is very good despite need for multiple reoperations in some.
While excellent surgical results have been reported for repair of complete atrioventricular septal defects (CAVSD) [1, 2], the need to readdress pathology of the left atrioventricular valve (LAVV) represents not only a therapeutic challenge, but also introduces the potential for considerable morbidity to the patient. The most common indication for reoperation after initial repair of AVSD is LAVV regurgitation with reported rates ranging up to approximately 20% [3–5]. The approach to reconstruction of the LAVV in the reoperative setting is especially crucial as durability of LAVV function has significant implications on long-term patient outcome [6, 7].
The surgical procedure is largely dictated by the anatomy of the valve, the mechanism of regurgitation, and the tissue quality present at the time of reoperation. Although LAVV repair is preferable to valve replacement and its associated morbidity (especially in children), this may not be feasible because of leaflet or subvalvular dysplasia secondary to progressive regurgitation [8]. Conversely, if a successful repair cannot be achieved, valve replacement may be necessary.
We report our experience with all reoperations after initial repair of CAVSD, describe intraoperative LAVV pathology, subsequent surgical decision making, and approach to LAVV repair or replacement. In addition, we evaluate the effect of valve repair or replacement at the first reoperation on long-term freedom from further reoperation and overall survival.
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Patients and Methods |
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The median interval between initial repair and first reoperation was 15 months (range, 3 days to 29 years), and at first reoperation median age was 4.5 years (range, 53 days to 38 years). Indications for first reoperation were LAVV regurgitation in 41, subaortic stenosis in 5, and LAVV stenosis, residual ASD, right pulmonary artery stenosis, and aortic coarctation in 1 each.
Statistical Analysis
Demographic and other patient-related data were obtained from Mayo Clinic medical records. Follow-up information was obtained from subsequent clinic visits, written correspondence from local physicians, and mailed questionnaires to patients or families. Data were expressed as median value with a range. Data between the two groups were compared using the Student paired t test. Risk factors were assessed using log-rank analysis. Survival and freedom from reoperation were determined using Kaplan-Meier analysis. Statistical significance was considered at a p value less than 0.05. Early operative mortality was defined as death occurring within 30 days of operation or at any time during the index hospitalization. The Mayo Foundation Institutional Review Board approved this study, and all patients or their families gave written informed consent.
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Results |
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Reasons for valve replacement included abnormal leaflet-edge pliability in 12 patients, severe annular dilatation in 5, multiple ruptured chordae in 3, and leaflet tethering in 1. Sizes of mechanical prostheses ranged from 16 to 29 mm and for the 3 tissue prostheses implanted, the sizes were 23, 25, and 25 mm. Overall, the median age of patients receiving a prosthetic valve was 5 years. The ages of the 3 patients that received a bioprosthesis were 6, 8, and 9 years. The median age of the 18 patients who received a mechanical prosthesis was 3 years and ranged from 53 days to 38 years. In small children less than 2 years old, a 16 mm was used in 3 patients, 27 mm in 2, and 19 mm in 1. There were no major bleeding or thromboembolic complications in patients who underwent LAVV replacement.
Further non-LAVV associated reoperations (after the first reoperation) included aortic valve replacement in 4 patients, and modified Konno procedure, septal myectomy, VSD repair, and combined Konno procedure + aortic root replacement in 2 patients each. In all, there were 78 reoperations in these 50 patients. Nine patients (18%) required postoperative permanent pacemakers (PPM); 7 after LAVV replacement (33%) for complete heart block in all and 2 after LAVV repair (9.5%) for sinus node dysfunction and bradycardia (p = 0.15).
Early nonfatal morbidity after the first reoperation is listed in Table 4. Complications after subsequent reoperations included pneumonia, urinary tract infection, atrial fibrillation, and subglottic stenosis in 1 patient each. There were 2 early deaths (4%) at the first reoperation. One patient who underwent initial CAVSD repair at 3 months of age and had moderate left ventricular hypoplasia developed cardiac failure postoperatively due to undiagnosed aortic coarctation and required reoperation for coarctation repair 5 days after initial CAVSD repair. She underwent coarctation repair and required extracorporeal membrane oxygenation postoperatively. She developed multisystem organ failure and expired after 3 days. The second patient underwent initial CAVSD repair at 2 years of age after palliation in infancy. He required reoperation for severe LAVV regurgitation 2 days after initial CAVSD repair due to multiple areas of septation patch dehiscence. He underwent successful patch re-repair, but developed intractable postoperative ventricular arrhythmias despite maximal medical therapy. There was no early mortality after subsequent reoperations.
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Comment |
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The LAVV pathology, specifically LAVV regurgitation, was the major indication for reoperation in our study, as well as others [4, 6, 9, 12–18]. Although the surgical management can be challenging, the ultimate choice of procedure did not affect late survival or need for further reoperation. Regurgitation of the LAVV has been shown to be progressive, but most commonly in the first 3 years after initial repair [19]. The median interval to first reoperation on the LAVV valve in our study was 16 months for patients who received a repair, and 13.5 months for those who underwent replacement. At the first reoperation, half of patients with LAVV pathology underwent valve repair and half underwent valve replacement. Interestingly, late survival and freedom from reoperation were not significantly affected by valve repair or replacement (Figs 1 and 2, respectively).
The ability to obtain a successful valve repair in this setting can be quite difficult given the multiple abnormalities that can be encountered with the CAVSD valve. Abnormalities that are particularly challenging include nonpliable anterior leaflet(s) and markedly abnormal leading edges. Consequently, multiple maneuvers may need to be employed to achieve valve competency. Repair methods employed in our experience are summarized in Table 3, and most commonly included cleft repair with or without annuloplasty. In these instances, both the extent of pathology and quality of tissue were judged to be adequate for re-repair. In all instances, valve competency was demonstrated with left ventricular saline injection and subsequently confirmed with intraoperative transesophageal echocardiography since 1988. In 3 instances marked valvar abnormalities resulted in unsuccessful valve repair, necessitating immediate valve replacement. Intraoperative judgment as to how much residual valve regurgitation to accept versus proceeding to valve replacement is individualized. Often, multiple reparative techniques are required and complex pathology is present; in this setting valve replacement would be favored.
Circumstances may not enable valve repair, and replacement may be required. While we prefer to avoid valve replacement, because of the morbidity associated with a prosthesis, significant valvar abnormalities may preclude a successful valve repair. Importantly, valve replacement does not preclude subsequent valve re-replacement (for somatic growth) and low early mortality with excellent long-term outcome has been reported in these circumstances [20, 21]. Intraoperative judgment as to how much residual valve regurgitation to accept prior to leaving the operating room is individualized. Often, multiple reparative techniques are required and complex pathology is present; in this setting, valve replacement would be favored.
For atrioventricular valve replacement, our practice has been to anticoagulate within 24 hours of surgery provided there is no ongoing bleeding. For mechanical atrioventricular valve replacement, we utilize low dose aspirin and warfarin aiming for an international normalized ratio (INR) of 3. If a repair is performed utilizing a band annuloplasty, low dose aspirin and warfarin are used striving for an INR of 2.5 for 3 months. After 3 months, the warfarin is discontinued. In simple atrioventricular valve repairs without a band annuloplasty we would recommend aspirin.
Our indications to reoperate on patients who develop LAVV regurgitation in the follow-up period closely follow those recommended for the patient without prior repair of ASD. First, we operate on patients who are symptomatic from valve disease. Second, we operate for moderate to severe regurgitation in the setting of left ventricular dilatation, decreased left ventricular function, or if the patient is having cardiac surgery for another reason (ie, coronary bypass grafting). Third, the decision to operate on the asymptomatic patient with severe LAVV regurgitation in the setting of a prior AVSD repair currently poses a clinical dilemma, for which there is no consensus. It is recommended to operate on asymptomatic patients with severe mitral valve regurgitation due to degenerative disease, so perhaps the indications for LAVV surgery should be expanded to include these patients with prior AVSD repair.
We found some interesting differences between those having valve repair versus valve replacement at the first reoperation (Table 1). First, median time interval from initial repair to first reoperation was slightly longer in those who went on to have valve repair (16 months) compared with those who required valve replacement (13.5 months). Although this is not statistically significant (p = 0.2), it is in contrast to prior reports and is almost twice as long as other reported intervals to first reoperation [8]. Increased time interval allows for increased exposure to increased volume overload and valve stress with more extensive valve deterioration, thus leading to greater need for valve replacement. In our series, these effects indeed were seen, as the most common reasons for valve replacement were extensive annular dilatation and abnormal leaflet pliability. Despite the longer interval to reoperation, in many patients, annular dilatation was commonly amenable to anuloplasty, and those who had repair performed had such for a previously unrepaired cleft, cleft repair failure, or simple dehiscence in the septation patch. In our experience, the most important factor was the extent of pathology (eg, marked valvar abnormalities, severe annular dilatation, etc). Second, although not statistically significant, more patients who received repair had Down syndrome (18 of 21) when compared with those undergoing replacement (13 of 21) (p = 0.08). It has been observed that patients without Down syndrome typically have more dysplastic valves, and this has been associated with higher reoperation rates [22]. This may have contributed to the good durability of re-repair in this subgroup, as 2 out of the 3 non-Down patients went on to have valve replacement after repair at the first reoperation while 15 of 18 Down syndrome patients remained free from valve reoperation. Third, more patients in the repair group (13 of 21) had cleft closure at the time of initial repair when compared with replacement patients (9 of 21) (p = 0.002). Dehiscence of the initial cleft repair was an indication for reoperation in 6 patients, and cleft re-repair was possible in all of these patients. Cleft re-repair was combined with an annuloplasty in 4 of 6 patients (67%); 1 patient (17%) required future valve replacement for repair failure. One out of 2 patients (50%) who had isolated cleft closure proceeded to require future valve replacement. No patient underwent leaflet augmentation techniques in this series. Fourth, as demonstrated in other studies [8, 13], the need for postoperative permanent pacemaker (PPM) tended to be higher in patients undergoing valve replacement (7 of 21) compared with valve repair (2 of 21). This did not reach statistical significance (p = 0.15). Not surprisingly, indications for PPM insertion were complete heart block in all 7 patients who underwent replacement compared with sinus node dysfunction in 2 patients after valve repair.
The valve re-repair rate in our series is lower than that of more recent reports [8]. We believe this is due to several factors. First, the median age at initial CAVSD repair is older than typically expected, which likely resulted in more cumulative stress on the valve leaflets. Second, many of these patients presented with markedly abnormal valves and, commonly, several reparative techniques used in conjunction would have been required to ensure valve competency. As noted before, 3 patients underwent attempted repair with subsequent valve replacement when an unsatisfactory result was noted in the operating room. Third, a few patients with chordal pathology underwent valve replacement early in the series, whereas, in the current era, the use of artificial chords may have facilitated valve repair in those patients.
In summary, LAVV repair after initial repair of CAVSD is possible, and is dependent on the extent of pathology that is present and quality of leaflet tissue. Valve re-repair was associated with similar late durability and late survival compared with valve replacement. Although repair is preferred, valve replacement may be necessary, and can be performed with low early mortality and excellent late survival, even in young patients. Late functional outcome is excellent, despite the need for multiple reoperations in some patients.
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Discussion |
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As a brief side note, I would encourage the authors (in case Professor Robert Anderson reviews your paper) to convert to the use of the phrase "zone of apposition" instead of "mitral cleft." As Professor Anderson has pointed out to us, the left AV valve in these patients is really not a mitral valve, and so we shouldn't be using the phrase "cleft."
But terminology aside, it seems clear that closure of the zone of apposition at the time of primary repair will help prevent late reoperation for left AV valve insufficiency. It was also interesting to me that you only had one patient operated on for left AV valve stenosis. Maybe we are not making these valves tight enough or small enough at the original operation.
One major difference between your series of patients and our group at Children's Memorial is your relatively high incidence of valve replacement, which was approximately 50%. In our series of 206 AV canal repairs since 1983, 17 patients, or 8%, have required left AV valve reoperation. Of those 17, only three, or 20%, have required a valve replacement. The primary repair used in the past many years at the Mayo Clinic was the classic single-patch technique, which requires division of the common AV valve leaflets and then reapproximation. I was curious as to whether you believed (because I believed this after reading your paper) whether that previous technique contributed to your inability to later repair the valve.
The other relatively interesting finding is the low incidence of reoperation for left ventricular outflow tract obstruction. There were only five patients out of a total of 513 primary procedures. The possibility of left ventricular outflow tract obstruction has been raised as a major potential issue for the modified single-patch technique, which we have recently adopted. What were the contributing factors to left ventricular outflow tract obstruction in these patients in regards to their primary operation? And as a side question, what is your current primary procedure of choice for these patients?
My final question is: what are your indications for reoperation on a patient with left AV valve insufficiency? As I read your manuscript I did not find the answer to this and I think many of us are curious. Was it moderate insufficiency, moderate to severe insufficiency, only severe insufficiency, only patients with symptoms? It is often very difficult for us to decide when to reoperate on one of these patients.
I enjoyed reviewing this excellent, thoughtful, and very complete manuscript. Thank you.
DR STULAK: Thank you, Dr Backer. We appreciate you agreeing to review our manuscript, and we acknowledge your excellent contribution in this area as well.
Your first question dealt with the high percentage of valve replacements we observed at the time of first reoperation. I think this is due to a few factors. First, this is a very diverse population, as you noted. The median age at initial repair for these patients was one year. This encompassed a 35-year period, during which, back in the 1970s, older age at initial repair was standard. Perhaps this resulted in more traumatized valves at the time of reoperation. Further emphasizing this point, we received 11 of these patients who had prior pulmonary artery banding before primary repair and thus were at an older age at that point. Second, many of these patients had complex valvular pathology resulting in complex regurgitant jets and complex leaflet abnormalities. As a result, multiple reparative techniques may have been required to repair the valve. So, in this setting, valve replacement represented the option that would afford the patient the most durable result.
Your second question dealt with the development of late left ventricular outflow tract obstruction. This late finding may be affected by our choice for primary repair. As I mentioned, our experience encompasses 35 years, during which a variety of techniques have been employed for primary repair. Initially, Dr McGoon employed the two-patch technique, and currently our approach is individualized; if the VSD [ventricular septal defect] is shallow, we favor the modified single-patch technique, and if the VSD is not shallow, then we favor the two-patch technique. It is hard to definitively comment on whether the type of primary repair utilized affects the late incidence of left ventricular outflow obstruction. Intuitively, one would think that the placement of a VSD patch may open up the LVOT [left ventricular outflow tract] and lessen the development of late obstruction. However, we are aware of the midterm results of the modified single patch, or simplified approach, in which there has basically been no reintervention for late LVOT obstruction. So, to answer this question definitively, the key will be to continue to follow these patients for a longer period of time.
The third question was regarding our indications for reoperation in these patients. Our indications to reoperate for regurgitation of the left atrioventricular valve closely follow the ACC [American College of Cardiology] recommendations to operate on mitral regurgitation in the non-AVSD patient with degenerative mitral valve disease. First, we operate on patients who are symptomatic from their valve disease. Second, we operate for moderate to severe regurgitation in the setting of left ventricular dilatation, decreased left ventricular function, or concomitant surgery for another reason. Third, the question of whether or not to operate on the asymptomatic patient with severe valvular regurgitation in this setting poses a clinical dilemma. We operate on patients with myxomatous valve disease in this setting, and perhaps we should expand the indications to reoperate on these AVSD patients as well.
DR ANDREW C. FIORE (St. Louis, MO): Since closing the zone of apposition is so crucial to avoid reoperation, as you read the original operative notes, could you correlate the technique of cleft closure with the subsequent need for reoperation and valve repair: simple sutures, mattress sutures, pledgeted sutures, Gore-Tex versus Prolene?
DR STULAK: Upon review of all the operative reports, it was interesting to note the differences as time progressed from the early part of the experience to the present. Dr McGoon used interrupted silk suture in this location and this evolved to interrupted Prolene sutures once these operations were mainly performed by Drs Danielson and Puga. In any setting, however, a surgical tenet that seemed to be respected by all surgeons was a hesitancy to ever use pledgets on the leaflet because of resultant scarring and subsequent decreased leaflet pliability that was inevitably seen at the time of reoperation. In addition, in noting the reasons for failure of cleft closure, most failures were observed in patients who had Prolene used at the time of primary repair that tore through a very dysplastic leaflet.
DR FIORE: Let's take a show of hands. How many use simple Prolene sutures to close the cleft? This is clearly the majority. How about Gore-Tex suture? Few surgeons. How about pericardial pledgets or Dacron pledgets with mattress sutures? Very few surgeons.
DR MICHAEL HINES (Winston Salem, NC): I have one quick question. We repair these at three or four months of age, and although the techniques are well established, this is in fact a relatively young operation, and I think it is unrealistic to expect that this valve, which is not a normal mitral valve, will last forever. So I routinely tell my patient's families that they will most likely have to have that valve worked on or replaced sometime in their lifetime. What do you tell your patients now based on your data?
DR STULAK: We agree totally with your statement. We have that frank discussion up front, and that is precisely the approach we take with our patients and their families. We stress that this is not a normal valve and counsel them regarding the potential for subsequent reoperations. We are very up front about that.
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