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Eur J Cardiothorac Surg 2004;25:728-734
© 2004 Elsevier Science NL
a Department of Thoracic and Cardiovascular Surgery, Seoul National University Bundang Hospital, Sungnam-shi, Kyungki-do, South Korea
b Department of Pediatric Cardiology, Sejong Heart Institute, Sejong General Hospital, 91-121 Sosa Bon 2-dong, Sosa-ku, Bucheon-shi, Kyungki-do 422-232, South Korea
c Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul, South Korea
d Department of Thoracic and Cardiovascular Surgery, Kyunghee University Medical Center, Seoul, South Korea
e Department of Cardiovascular Surgery, Sejong Heart Institute, Sejong General Hospital, Bucheon-shi, Kyungki-do, South Korea
Received 21 September 2003; received in revised form 10 January 2004; accepted 23 January 2004.
* Corresponding author. Tel.: +82-32-340-1123; fax: +82-32-340-1236
e-mail: dire7613{at}chol.com
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Abstract |
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 Top Abstract 1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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Key Words: Right ventricle • Pulmonary regurgitation • Congenital
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1. Introduction |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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However, debate on the proper timing of PVR after repair of TOF is still continuing [9–12]. In a recent report by Therrien et al. [9], RV functional recovery after PVR for chronic PR was compromised in the adult population, and the authors suggested that earlier PVR should be considered before RV function deteriorated. Leiden group [12–14] also showed the rationale of earlier PVR using dobutamine stress magnetic resonance imaging (MRI) and brain natriuretic peptide level.
The precise assessment of RV function is difficult because of its structural complexity and altered loading conditions, especially in patients with PR and associated lesions. Preoperative parameter predicting postoperative RV performance and long-term outcome after PVR in patients with chronic PR was not clearly defined yet. And there is still a concern about the risk of later reoperation for prosthetic valve failure.
The purposes of our study were to examine the results and effectiveness of PVR after repair of TOF, and to find out potential risk factors contributing to poor late outcomes. Our primary focus on this study was to investigate the parameters regarding the proper surgical timing of PVR.
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2. Materials and methods |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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The initial TOF repair was done at a mean age of 5.2±7.1 years (range 0.5–34 years). PVR was performed at a mean age of 13.5±9.6 years (range 1.2–44 years) with a mean duration from repair to PVR of 8.3±5.2 years (range 4 months–28 years). Fifteen patients had undergone palliative procedures before intracardiac repair. A transannular patch had been used in 49 patients (84.5%). Sixteen patients had additional interventional or surgical procedures before PVR; balloon pulmonary angioplasty and/or stent implantation in 11 and surgical pulmonary angioplasty in three for branch pulmonary artery stenosis, and RV outflow track reconstruction with pulmonary artery angioplasty in two.
PVR was generally considered in patients with (1) exercise intolerance or signs and symptoms of right heart failure, or (2) associated lesions besides PR such as TR or pulmonary artery stenosis, or residual ventricular septal defect, or (3) symptomatic arrhythmia, or (4) RV dilatation and dysfunction assessed by qualitative 2D echocardiography or right ventriculography.
Before PVR, 29 (50%) patients had reduced exercise tolerance and were in New York Heart Association (NYHA) functional class II (n=20), III (n=7), or IV (n=2). Ten patients showed clinical signs of right heart failure such as generalized edema. Tricuspid regurgitation of more than moderate degree was observed in 18 patients. Branch pulmonary artery stenosis or distortion was observed in 38 patients. RV outflow track obstruction with more than 40 mmHg of pressure gradient was observed in two patients. Five patients had residual ventricular septal defect of more than moderate size.
RV dysfunction and enlargement were subjectively classified into mild, moderate, and severe grades. In these criteria, preoperative echocardiography (n=58) showed moderate to severe RV dilatation in 44 patients (76%), and moderate to severe RV dysfunction in seven patients (12%).
Eight patients had symptomatic arrhythmias (atrial flutter and/or fibrillation in six, and sustained ventricular tachycardia in two). Six of them were more than 20 years of age. Preoperative electrocardiogram showed complete right bundle branch block in 49 patients (84.5%). Mean duration of QRS complex was 142±30 ms. Long QRS duration (more than 180 ms) was observed in eight patients. Patients' demographic data are summarized in Table 1.
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2.3. Surgical technique
After the induction of general anesthesia and full invasive monitoring, redo midline sternotomy incision was made using oscillating saw. Femorofemoral bypass was used when appropriate, i.e. bleeding during redo-sternotomy. Careful dissection of substernal adhesion was performed using both blunt and sharp dissections with electrocautery. After institution of routine cannulation and moderate systemic hypothermia around 30 °C, electrical ventricular fibrillation was induced and the RV outflow tract was opened longitudinally over the annulus of pulmonary valve. In case of residual ventricular septal defect or other intracardiac problem, aortic cross clamping and antegrade intermittent cold blood cardioplegia was used.
PVR was performed using various prosthesis including bioprosthesis, mechanical prosthesis and homograft as available. There was no randomization in choice of valve, and it usually depended on individual surgeon's preference. There were three mechanical valves, 23 porcine bioprostheses, 20 pericardial bioprostheses, 11 stentless bioprostheses, and 1 homograft valve.
Valve substitute was inserted into the true pulmonary valve annulus using 4–0 polyprophylene continuous sutures. Stentless valves and homograft were inserted more distally to avoid sternal compression. Aneurysmal dilatation of RV outflow tract was excised or plicated. In order to insert larger pulmonic valve, anterior aspect of valve substitute was covered with bovine pericardial patch. Any kind of pulmonary artery stenosis was concurrently enlarged with the same patch. Patients with significant arrhythmia received anti-arrhythmic surgery using cryoablation and right side maze procedure [16]. Recently, we used synthetic patch made of enhanced-polytetrafluoroethylene (Gore-TexTM) to cover the anterior surface of the heart in order to facilitate safer and faster re-entrance of sternum during inevitable future re-operations.
2.4. Statistical analysis
Statistical analysis was performed with the Statistical Analysis System software package (version 6.12; SAS Institute, Cary, NC). Comparison between preoperative and postoperative continuous variables such as cardiothoracic ratio was performed by paired t-test. The significance of differences between two groups was assessed by Student's t-test, 
2-test or Fisher's exact test as appropriate. Freedom from reoperation was analyzed using Kaplan–Meier method. All results were expressed as mean±standard deviation and a value of P<0.05 was considered statistically significant. Multivariate analysis was not done.
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3. Results |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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Four out of six patients, who had atrial arrhythmia preoperatively, underwent anti-arrhythmia surgery including cryoablation and right-side maze procedure, two with concomitant pacemaker insertion due to sinus node dysfunction. Two had returned to normal sinus rhythm postoperatively and another two showed AAI- and DDD-type pacing rhythm without atrial arrhythmia. One of the two patients without arrhythmia surgery had persistent atrial fibrillation with ventricular rate control and the other was a mortality case. New-onset atrial flutter developed in one patient with severe PR, TR, severe right atrial enlargement, and right heart failure. Right atrial reduction plasty was done without prophylactic cryoablation. She was on anti-arrhythmic therapy now. In one of the two patients who have had ventricular tachycardia preoperatively, sustained monomorphic ventricular tachycardia was recurred a year after operation and well controlled with ß-blocker. The other was free of arrhythmia 18 months after the operation. On follow-up electrocardiogram, the mean duration of QRS complex did not change (142±30 to 144±30 ms, P=0.05).
Redo-PVR was performed in six patients during postoperative follow-up. Mean duration of PVR to redo-PVR was 5.3±2.5 years (range 1.1–8.2 years). Two of them had first PVR with mechanical valves, two with pericardial valves, one with FreeStyleTM stentless valve, and one with aortic homograft. Actuarial freedom from redo-PVR at 5 years post-PVR was 87.9±9.5% (Fig. 1) .
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4. Discussion |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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Although long-term functional results of patients after TOF repair were excellent, the negative effects of chronic PR as a result of RV outflow track reconstruction on RV function, cardiac electrophysiology, and life expectancy were well recognized [1–4]. Previous reports demonstrated that PVR had beneficial effects on symptoms, RV function, and arrhythmia propensity in patients with repaired TOF [6–8,17]. These findings were consistent with those of our study. Cardiothoracic ratio was decreased and RV dilatation and dysfunction on echocardiography improved substantially. Symptomatic improvement was marked.
However, optimal timing of PVR is still a subject of debate. Exercise intolerance or symptoms of right heart failure, significant arrhythmia, evidence of RV dysfunction, and development and progression of TR have been generally accepted as indications for PVR, as were in our study [8]. But precise evaluation of exercise tolerance is somewhat complex because of the lack of uniform standards for exercise testing in patients with congenital heart disease [18,19]. And the assessment of RV function is also complex because of its complex structure and altered loading conditions in repaired TOF [14]. So, the results are variable between study groups [7,9,14,20].
Bove et al. [7] found a reduction in RV volume (measures with M-mode echocardiography) and improved RV ejection fraction (measured with radionuclide angiogram) after PVR in a group of patients with mean age of 14.6 years. Subjective improvement in exercise tolerance was also recorded. On the contrary, Therrien et al. [9] found no reduction in RV volumes after PVR using radionuclide angiogram and no improvement of exercise capacity in a group of adults with a mean age of 33.9 years, despite substantial improvement of functional class. They suggested that earlier PVR should be considered before RV function deteriorated. In contrast, recent report on a group of patients with a mean age of 29.2 years, dramatic improvements were noted in MRI follow-up [14]. That showed reduction of RV volume and improvement of RV ejection fraction corrected for regurgitation and RV end-systolic volume. These discrepancies may be basically due to the differences in methods measuring the RV volume and function [9]. But another explanation is that the ages at TOF repair or PVR are different among groups. The patient population reported by Bove et al. [7] was significantly younger at the time of PVR (mean of 14.6 vs 33.9 years, respectively) than those of Therrien et al. [9]. This implies that the potential for contractile recovery and ability to undergo remodeling after PVR may diminish over time and earlier PVR should be considered in adult population. The age at initial TOF repair also may have influence on the late outcome. The mean ages at the time of PVR in the patients reported by Therrien et al. [9] and Vliegen et al. [14] were similar (
30 years), but the mean ages at initial TOF were different (mean of 5.7 vs 12.1 years, respectively). These findings are consistent with our study, showing that older age at PVR and at initial TOF repair caused adverse effect on postoperative outcomes. Prolonged exposure to cyanosis and pressure overloading before total correction, and inadequate myocardial protection during cardiopulmonary bypass and direct myocardial injury at the time of initial repair may impair the ability to recover after PVR in aged RV [9].
The longer time interval from the initial repair to PVR and preoperative poor functional class were other risk factors to poor outcomes in our study. Conte et al. [20] also found that the patients who did not have major benefits from PVR had been previously exposed to PR for a considerably longer time than the others (mean interval between initial repair and PVR, 18.7 vs 12.6 years, P=0.01). Moreover, the patients who underwent PVR more than 15 years after initial repair had only mild reduction in RV dilatation after PVR.
Ilbawi et al. [21] have reported complete recovery of RV function and work performance only in patients who had PVR within the first 2 years after TOF repair, while in all the other patients who had PVR at a later time (2–13 years after TOF repair), RV function remained abnormal and exercise tolerance did not improve significantly. They explained these findings with already existing irreversible myocardial damage before PVR. They suggested early recognition of patients at risk of developing RV failure to proceed with PVR in time to have greater benefits and to prevent irreversible deterioration in RV function. Therefore, waiting for symptoms to appear may allow irreversible RV dysfunction to occur and result in minimal benefits from PVR.
The exact timing of PVR would not be defined yet in our study because of the subjective nature of diagnostic criteria. Actually we cannot define the objective criteria yet. However, according to our results, older age at PVR and longer duration from TOF repair to PVR were the risk factors of poor outcome. Other report regarding PVR in the adult age [9] also showed that recovery of RV dysfunction was impaired. So we think that PVR should be considered at least in the patient of late adolescence or early adulthood.
Arrhythmia including ventricular tachycardia and atrial flutter or fibrillation may cause decreased cardiac output, increased exercise intolerance, and sudden cardiac death. Gatzoulis et al. [3] described in their multicenter trial that the risk factors for arrhythmia and sudden cardiac death were QRS prolongation, older age at repair, pulmonary valve regurgitation, and TR. They suggested that preservation or restoration of pulmonary valve function might reduce the risk of sudden death and electrocardiographic markers could help to identify patients at risk. Toronto group [17] also reported that PVR led to stabilization of QRS duration and, in conjunction with intraoperative cryoablation, to a decrease in the incidence of preexisting atrial or ventricular tachyarrhythmia. In our study, the stabilization of QRS duration was also recorded. Eight patients had significant arrhythmia preoperatively and four of them received anti-arrhythmia surgery including cryoablation and right-side maze procedure. Postoperatively, atrial arrhythmias disappeared and all four patients are doing well in a recent follow-up. But in one adult patient who had severe TR and severe right atrial enlargement but no preoperative arrhythmia, new atrial flutter developed, although TR was well corrected and right atrial reduction plasty was done. We think that in patients with prolonged severe TR and right atrial enlargement, prophylactic right cryoablation should be considered. Right atrial dilatation from volume or pressure load prolongs atrial refractoriness in a heterogeneous manner. This dilatation, together with right atrial scarring from previous surgery, makes the atria susceptible to reentrant arrhythmia, even after PVR and TR corrections [3,17]. In our opinion, patients with atrial flutter or fibrillation should receive both cryoablation and right side maze procedure. Also, in a patient with ventricular tachycardia, both electrophysiologic study and cryoablation should be considered. It would be the best option to improve post-PVR outcome and to reduce the potential risk of sudden cardiac death.
The mean age at operation was 5.2 years in our study with an incidence of transannular patching of 84.5%. The state of the art now is to correct earlier using less a transannular approach. A recent trend in our institution is early repair of TOF (less than 12 months of age). We are trying to save the pulmonary valve as long as we can. We hope that this will decrease the incidence of late RV dysfunction.
Limitation of our study includes rather subjective evaluation of postoperative changes, such as symptoms, exercise tolerance and RV function on echocardiography. Until recently, there is no gold standard to evaluate the RV functional reserve objectively and quantitatively, because of the complex geometry of RV. Assessment of RV function by M-mode or 2D echocardiography has fundamental drawbacks. But, this modality is rather simple, and even though not perfect, easy to apply to routine and regular follow-up. More objective measures to evaluate the RV functional reserve such as dobutamine stress MRI, brain natriuretic peptide level or radionuclide study will be needed in the future studies [9,13,14]. MRI is now emerging as a gold standard technique to assess RV size and function. Recently, we are performing cardiac MRI with cine-MRI to evaluate the RV size and function objectively in the prospective manner. But the study period is still short and more data collection will be needed to support our policy in earlier PVR. Although uniform standard for exercise testing in patients with congenital heart disease is lacking, exercise test with maximal oxygen consumption rate is desirable for a more complete assessment of objective exercise capacity [18,19].
In conclusion, PVR after repair of TOF can be performed with low mortality and morbidity and it can improve the RV function, functional class and patient's physical activity. Also it can reduce the possibility of life threatening arrhythmia and sudden death. Risk factors that may cause poor late outcomes are older age at initial TOF repair, older age at PVR, longer interval from TOF repair to PVR, poorer preoperative functional class, larger cardiothoracic ratio, and presence of significant arrhythmia. Therefore, earlier replacement of chronically regurgitant pulmonary valve after repair of TOF should be considered before deterioration of RV function and functional class even in asymptomatic patient, especially in the adult population.
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Acknowledgments |
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Footnotes |
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Appendix A. Conference discussion |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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Dr Lim: We have 6 reoperations in this cohort. But in the case of a mechanical valve we used, 2 or 3 of the mechanical valve have thrombosis, so we do not prefer this type and 1 patient with homograft graft with 14 mm of annulus failed due to the calcification of homograft.
Dr Ebels: My question was, when do you want to operate? Not what valve, but when?
Dr Lim: The focus of our study is the timing. So we generally recommend that if the patient has symptoms, we recommend immediate replacement.
But more importantly, in asymptomatic patients, we recommend they come in to our outpatient department and we thoroughly check the chest X-ray or echocardiography. And if any sign of like tricuspid regurgitation or progressive increase in RV dilatation, we generally recommend operation. In my opinion, the proper timing is about no longer than 10 years after the initial repair.
Dr G. Sarris (Athens, Greece): I have two questions. One is similar to Dr Ebels' question. I think most people would agree that the symptomatic patient—and I notice 50% of your patients were symptomatic—should be offered pulmonary valve replacement.
In the asymptomatic patient group, your criteria were not well delineated. You just alluded to serial echocardiographic findings that may be useful. Have you used any more detailed studies of right ventricular volume or function serially, such as CMR, or any provocative tests, such as exercise testing, trying to identify a subpopulation of otherwise asymptomatic patients with significant PI and select them out for pulmonary valve replacement?
And the second question is, since prevention may be even more important, whether your technique of tetralogy repair initially is a transventricular or a transatrial technique, since the latter may preserve pulmonary valve function better.
Dr Lim: I think that the objective criteria is not known yet. So we try to find the objective criteria and get objective studies like MRI study. But the study result is not ending yet, because the time period is very short.
But I think usually a patient without symptoms restricts his activity, so he doesn't want to play together with his friends and the objective symptom is maybe masked. So in outpatient department we carefully examined through the questionnaire that, Are you okay? But in asymptomatic patient, he generally restricts his activity. So the functional class is underestimated.
So we generally recommend the PVR in asymptomatic patient is rather subjective, and we don't know how to correctly indicate the indication of PVR right now.
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References |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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