Asian Cardiovasc Thorac Ann 2005;13:139-142
© 2005 Asia Publishing EXchange Ltd
Late Pulmonary Valve Implantation after Repair of Tetralogy of Fallot
Shengli Yin, MD1,
Jorge Salazar, MD,
Lars Nolke, MD,
Anthony Azakie, MD,
Tom R Karl, MD
Division of Pediatric Cardiothoracic Surgery, University of California, San Francisco, USA
1 Sun Yat-sen University, Guangzhou, China
For reprint information contact: Tom R Karl, MD Tel: 1 415 476 3501 Fax: 1 415 476 9678 Email: karlt{at}surgery.ucsf.edu, Division of Pediatric Cardiothoracic Surgery, University of California San Francisco, 513 Parnassus Avenue, S549, Box 0117, San Francisco, CA 94143-0117, USA.
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ABSTRACT
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Ten cases of elective late pulmonary valve implantation after repair of tetralogy of Fallot were reviewed. The interval after initial repair ranged from 1.5 to 43 years (mean, 20.0 ± 12.3 years). There was no hospital mortality or late death during a mean follow-up of 12.5 months. Preoperatively, 9 patients were in New York Heart Association functional class III–IV; after pulmonary valve implantation, all 10 patients were in class I–II (average improvement, 1.7 classes). Left ventricular ejection fraction improved significantly (from 62.1% ± 4.7% to 70.2% ± 4.9%), as did fractional shortening (from 34.0% ± 5.0% to 40.0% ± 4.2%). Right ventricular diameter decreased significantly (from 32.3 ± 7.5 to 24.4 ± 5.4 mm). QRS duration decreased significantly (155.2 ± 27.1 vs. 140.0 ± 21.2 msec), but there was no significant difference in QT interval (460.9 ± 29.6 vs. 451.9 ± 50.6 msec). Hospital stay was 4–7 days. One patient had preoperative ventricular fibrillation requiring resuscitation and an implantable cardiac defibrillator; another needed a defibrillator at the time of pulmonary valve implantation, because of ventricular arrhythmias. It was concluded that late pulmonary valve implantation after tetralogy of Fallot repair had significant benefits and carried low operative risk.
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INTRODUCTION
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Repair of tetralogy of Fallot (TOF) has been accomplished with success over the last 50 years, and a favorable long-term outcome has been documented for most patients.1–4 However, there is a small proportion of patients who need reoperation late after TOF repair. Indications for reoperation have included severe pulmonary regurgitation or stenosis, residual ventricular septal defect, residual right ventricular (RV) outflow tract obstruction, conduit degeneration, aortic valve regurgitation or stenosis, and tricuspid valve regurgitation.1,3 Long-term severe pulmonary valve regurgitation may lead to RV volume overload and dilation. Exercise tolerance decreases, lower limb edema develops, and some patients may suffer ventricular arrhythmias and sudden death.5 Pulmonary valve implantation (PVI) can reverse right heart volume overload, and the dilated right ventricle can return to normal dimensions.6,7 Cardiac reoperation is relatively high-risk in the mind of many clinicians; therefore, the risk of reoperation versus the benefit of PVI must be considered. To this end, we reviewed the 10 cases of late PVI carried out by our current surgical team.
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PATIENTS AND METHODS
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Ten patients (9 male, 1 female) underwent late PVI after TOF repair. Their hospital charts and echocardiogram records from June 2002 through April 2004 were reviewed. Pulmonary insufficiency, tricuspid insufficiency, and RV dysfunction and enlargement were subjectively classified as none, mild, moderate, or severe on echocardiography, catheterization, or magnetic resonance imaging (MRI). All patients undergoing PVI had an echocardiographic evaluation preoperatively, after the operation, and before discharge. Late follow-up echo data was available for 5 of the 10 patients. Seven patients underwent catheterization before PVI, and 3 were studied by MRI. Electrocardiograms (EKG) were analyzed preoperatively, postoperatively, and pre-discharge. All patients underwent standard surgical techniques including a repeat sternotomy, femoral or ascending aortic cannulation, and cardiopulmonary bypass with a beating heart. All PVI and concomitant procedures were performed without aortic crossclamping. Follow-up was carried out by the primary cardiologist.
Comparisons of preoperative and discharge echo measurements, catheterization data, and EKG findings were made using the paired Student t test.
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RESULTS
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The mean age at TOF repair was 4.2 ± 6.0 years (range, 0.2–17 years). The mean age at PVI was 24.9 ± 17.4 years (range, 2.0–61 years). The interval between repair and PVI was 20.0 ± 12.3 years (range, 1.5–43 years). All patients underwent PVI because of severe pulmonary regurgitation after TOF repair (9 patients) or pulmonary atresia with TOF (1 patient). Palliative operations were performed in 3 patients before TOF repair: a modified Blalock-Taussig shunt in 2, and a Potts shunt in the other. Five procedures were performed in 5 patients after TOF repair and before PVI: left pulmonary artery balloon dilation was carried out in two, revision of a right ventricle–pulmonary artery connection with patch was undertaken in one, an atrial septal defect was closed by catheterization in one, and an internal cardioversion device was implanted in another. Management of RV outflow during TOF repair was via a transannular patch in 9 patients and by pulmonary valvotomy with no patch in one.
All patients studied had severe pulmonary insufficiency. Preoperatively, one patient was in New York Heart Association (NYHA) functional class II, 7 were in class III, and 2 were in class IV; after PVI, 6 were in class I and 4 were in class II. The average improvement was 1.7 NYHA classes. The ECG showed a long QRS duration in all patients before PVI; whereas after PVI, QRS duration decreased significantly (from 155.2 ± 27.1 to 140.0 ± 21.2 msec, p = 0.048). However, there was no significant difference in the QT interval (460.9 ± 29.6 vs. 451.9 ± 50.6 msec, p = 0.614). Before PVI, supraventricular arrhythmias occurred in 2 patients and ventricular fibrillation in one; another patient required implantation of a cardiac defibrillator at the time of PVI.
To evaluate right heart function, 3 patients underwent preoperative MRI which showed that the right atrium, right ventricle, and pulmonary artery were markedly enlarged, with free pulmonary insufficiency. Their RV ejection fractions were 46%, 25%, and 23%; and pulmonary artery retrograde flows were 32%, 45%, and 50% (Figure 1
). Seven patients had pre-PVI heart catheterization (Figure 2); their hemodynamic data are shown in Table 1. After PVI, right ventricle and pulmonary artery size were significantly decreased on echocardiography, while left ventricular ejection fraction and fractional shortening were significantly improved (Table 2).
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Figure 2. Magnetic resonance image demonstrating severe pulmonary insufficiency. PA = pulmonary artery, RV = right ventricle.
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All PVI procedures employed Carpentier-Edwards bovine pericardial valves (Baxter Healthcare Corp., Irvine, CA, USA), ranging from 19 to 27 mm. There was a low post-PVI gradient across the RV outflow tract to the pulmonary artery in all patients (mean systolic peak gradient, 14.5 mm Hg; range, 8–30 mm Hg). Hospital stay ranged from 4 to 7 days, with a mean of 5.4 days. There was no hospital death. During PVI, 4 of the 10 patients needed additional procedures. One had left pulmonary artery plasty, 2 underwent closure of a patent foramen ovale, and one had a cardiac defibrillator implanted. Mean follow-up was 12.5 months (range, 1–22 months). All patients denied any discomfort, and activity tolerance improved significantly.
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DISCUSSION
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Numerous studies have demonstrated very good long-term survival and quality of life after TOF repair in the majority of patients.1–2 As the number of long-term survivors of TOF repair increases, so does the number of late complications. In general, pulmonary insufficiency is well tolerated; however, over time, severe pulmonary insufficiency will lead to RV dilation, dysfunction, and sometimes fatal ventricular arrhythmias. Many studies have focussed on PVI in patients, or via catheterization in animals, to reconstruct the pulmonary valve; the results have been favorable.5–10 Zhou and colleagues8 demonstrated a satisfactory treatment for pulmonary insufficiency in adult pigs, with a large self-expanding valved stent. Isolated PVI with cardiopulmonary bypass is safe for patients: more than 95% of those who had late PVI after TOF repair survived in the long-term follow-up, with very few cardiac-related deaths.6–7 In our experience, all patients did well and demonstrated decreased RV size, better heart function, and improved exercise tolerance. Discigil and colleagues7 also found that functional class improved significantly: preoperatively, 76% of their 42 patients were in NYHA class III–IV; after PVI, 97% of the 41 surviving patients were in class I–II. Yemets and colleagues 6 reported on 85 patients who had late PVI after TOF repair: operative risk was low (1.1%), and 90% of survivors were in NYHA class I.
In our study and others, PVI was an effective and low-risk operation for treatment of severe pulmonary insufficiency after TOF repair. Therefore, when is PVI indicated? Is it possible that all patients who have TOF repair will ultimately need PVI? Determining the most appropriate time for PVI in patients with significant pulmonary insufficiency is difficult. Ideally, all important anatomic lesions should be treated early to avoid deterioration of RV function and development of associated problems.7 However, bioprostheses have limited durability, and one would like to avoid PVI until it is clearly indicated.7 We used the following criteria to select patients who would benefit from PVI after TOF repair: palpitations associated with pre-syncope or syncope; markedly decreased exercise tolerance; evidence of moderate to severe RV enlargement caused by free pulmonary insufficiency; right-sided heart failure with ascites or peripheral edema; development or progression of tricuspid regurgitation; Holter recording or EKG showing atrial flutter or fibrillation, or sustained monomorphic ventricular tachycardia on electrophysiological testing. In addition to PVI, we recommend concomitant repair of all additional anatomic lesions (atrial or ventricular septal defects, tricuspid regurgitation, surgically accessible proximal and distal pulmonary artery stenoses, and arrhythmias or heart block) to allow optimal recovery of RV function.
After TOF repair with significant pulmonary insufficiency, patients may remain asymptomatic for a long time. In our group, the mean time to PVI was 20.0 ± 12.3 years compared with 9.7 and 9.3 years in other reports.6,7 Previous studies have demonstrated correlations between atrial flutter/fibrillation or monomorphic ventricular tachycardia and long QRS duration due to right-sided heart enlargement and the occurrence of sudden death.3,11–13 We demonstrated that QRS duration can decrease after PVI, but there was no difference in QT interval. Free pulmonary insufficiency not only causes arrhythmias but also leads to increased RV pressure with a consequent decrease in left heart function. In our catheterization and MRI studies, RV pressures rose although there was no RV outflow obstruction in most patients, and the peak systolic RV-left ventricular pressure ratio rose to 0.46 ± 0.16. Pulmonary insufficiency and RV outflow aneurysm/akinesia were independently associated with RV dilation, and the latter with hypertrophy late after TOF repair. Left ventricular systolic dysfunction correlated with RV dysfunction, suggesting an unfavorable ventricular interaction.14 Echocardiography and MRI are both good for evaluating RV ejection fraction, but severe pulmonary insufficiency may affect RV ejection fraction values. Greater clarity can be achieved with MRI, and output can be calculated more accurately than with echocardiography. In this study, no MRI or catheterization data after PVI was available.
Yemets and colleagues6 demonstrated that 10-year survival after PVI was 95%, with 86% of patients free from reoperation for valve failure. Durability and freedom from reoperation may depend on the type of valve prothesis. Porcine valves were used in all patients in the study by Discigil and colleagues7 who noted that 8 of 42 patients needed redo PVI at a mean interval of 9.0 ± 4.2 years. The only significant risk factor for reoperation was young age at the initial PVI. The durability of the porcine bioprosthesis was found to be better than that of cryopreserved homografts.7 Rosti and colleagues15 also had good results with mechanical valves in the pulmonary position. Complications were seen in patients with bileaflet mechanical valves, and the tilting disc valve was considered superior. Homograft implantation is technically more difficult and homografts are scarce. After mechanical valve implantation, life-long anticoagulation is required. The RV outflow tract was wide in our patients and thus a pericardial bioprosthesis was chosen. However, late follow-up of pericardial valves needs further study.
It was concluded from this study that late PVI after TOF repair significantly improves left ventricular function, NYHA functional class, and exercise tolerance, while decreasing right ventricular size. Furthermore, pulmonary valve implantation can be performed with low operative risk.
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REFERENCES
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ABSTRACT
INTRODUCTION
