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Ann Thorac Surg 2007;83:1790-1795
© 2007 The Society of Thoracic Surgeons
a Department of Cardiovascular and Thoracic Surgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
b Department of Cardiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
Accepted for publication January 9, 2007.
* Address correspondence to Dr Shyamkrishnan, Department of Cardiovascular and Thoracic Surgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, Kerala, India (Email: kgs{at}sctimst.ac.in).
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Abstract |
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Methods: Fifty-eight patients older than 18 years operated on between January 1995 and June 2004 are included in the study. Mean age at surgery was 22.5 ± 5 years. Forty-seven patients were in New York Heart Association functional class II and 11 were in class III. Two patients had previous shunts. Forty-four patients received a transannular patch, and 14 had a right ventricular outflow tract patch. The prospective arm objectively assessed postoperative ventricular function by treadmill testing and echocardiography.
Results: Hospital mortality was 6.9%. Follow-up was 89% complete, with mean follow-up of 69.9 ± 43 months. Late mortality occurred in 2 patients, both with infective endocarditis. Significant improvement in functional class was demonstrated (p < 0.001). Eight patients had significant pulmonary regurgitation on follow-up. The probability of survival after repair was 89% at 15 years. Thirty-five of 36 patients who underwent treadmill testing had good effort tolerance, with an average of 10.47 ± 1.4 metabolic equivalents achieved. None had a positive result. One patient with transannular patch, in functional class III, had fair exercise tolerance with severe pulmonary regurgitation on echocardiography.
Conclusions: Repair of adult tetralogy of Fallot has acceptable morbidity and mortality rates with good long-term surgical outcome in terms of effort tolerance as demonstrated by treadmill testing. Transannular patching does not appear to be a significant risk factor for right ventricular failure at long-term follow-up.
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Introduction |
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TopAbstractIntroductionPatients and MethodsResultsCommentAcknowledgmentsReferences |
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The long-term outcomes of corrective surgery for this patient population are less well known [1, 2, 4]. We present the outcomes of surgical correction in an adult population at long-term follow-up, including results of objective assessment of postoperative effort tolerance as evaluated by treadmill testing.
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Patients and Methods |
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TopAbstractIntroductionPatients and MethodsResultsCommentAcknowledgmentsReferences |
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Mean age at surgery was 22.5 ± 5 years, ranging from 18 to 36 years. The male-to-female ratio was 1.7:1. Effort intolerance was the presenting symptom in 56% cases, and cyanosis was the chief symptom in 38% cases; 34.5% of patients gave a history of squatting at some point in the past. Preoperative history of neurologic complications was present in 10 of 58 patients (17.2%), with 8 having a history of brain abscess and 2 giving a history of seizures. Five (8.6%) of the above patients also had history of a preoperative stroke, with complete recovery in 3 cases before surgery. Forty-seven patients were in New York Heart Association functional class II and 11 patients were in class III at the time of surgery. Two patients (3.4%) had previous shunts, one modified and classic Blalock-Taussig shunt each. The preoperative hematocrit ranged from 37% to 82%, with a mean of 60.7% ± 12%. Cyanosis was not clinically evident in 10.3% of patients. The average preoperative saturation was 79.2% ± 5.97%.
Preoperatively, all patients maintained sinus rhythm, with 1 having frequent premature right ventricular ectopics. Chest roentgenography revealed right aortic arch in 4 of 58 patients (6.9%), and 3 patients had a chest or sternal deformity.
Preprocedure catheterization study was carried out in 50 patients (86.2%). The preoperative RVOT gradient ranged from 52 to 130 mm Hg, with a mean of 76.7 ± 17 mm Hg. The site of obstruction was infundibular alone in 34 patients (58.6%), valvar alone in 3, and combined infundibular and valvar in 21 (36.2%). There was an element of associated supravalvar narrowing in 5 patients. The mean preoperative pulmonary annulus was 13.7 ± 4 mm. The mean diastolic diameter of the right ventricle preoperatively was 22.7 ± 5 mm.
The typical large subaortic ventricular septal defect (VSD) was seen in 56 patients, and 2 had a doubly committed VSD. One patient had an additional muscular VSD.
Surgical Procedure
All surgeries were performed by a single surgeon, utilizing standard cardiopulmonary bypass. In the latter half of the study, we routinely used aprotinin, 50,000 KIU/kg body weight, added to the bypass circuit, to minimize the incidence of postoperative bleeding. In all patients, a transatrial approach was used to assess the pathology and close the VSD using a tailored Dacron (C.R. Bard, Haverhill, Pennsylvania) patch with interrupted mattress sutures. Adequate resection of the infundibular (septal and parietal) bands was carried out by a separate limited vertical right ventriculotomy aligned with pulmonary trunk long-axis, avoiding any major coronary branches. The decision to extend the incision across the pulmonary valve was based on the adequacy of annulus, as estimated by the "z-value" preoperatively and also reevaluated on table. The required annulus for the body surface area was determined by standard normograms, and the corresponding size Hegar dilator was used to judge both the necessity of a transannular patch and the width of the transannular patch, if used.
In 44 patients, the repair necessitated a transannular patch, and 14 received an RVOT patch. A pulmonary valvotomy was carried out for 3 patients in the RVOT patch group. The intraoperative ratio of the right to left ventricular pressure was measured in all cases, with a mean value of 0.6 ± 0.2. A value of 0.8 was considered the cut-off point for RVOT revision, but with one exception: a patient with a transannular patch, no demonstrable gradient across the RVOT, and with good intraoperative hemodynamics had a value of 0.9. The mean aortic cross clamp time was 130 ± 26.5 minutes, and the mean cardiopulmonary bypass time was 195 ± 37.8 minutes.
Prospective Evaluation
The prospective arm of the study was based on a clinical assessment of patients’ status and included objective assessment of postoperative ventricular function by treadmill testing and electrocardiography along with echocardiography specifically delineating right ventricular function. The consent of every patient was taken before prospective evaluation. However, 10 of the 46 patients, on follow-up, declined evaluation by treadmill testing. Of the 36 patients who underwent treadmill testing, 8 had surgery with the RVOT patch whereas 28 had a transannular patch; none had a previous shunt. All of the patients had evaluation of right ventricular function by echocardiography.
The treadmill test was carried out in accordance with standard Bruce protocol (Marquette T-2000 Treadmill; GE Healthcare, Waukesha, Wisconsin) along with electrocardiography and blood pressure monitoring. The exercise capacity was interpreted in terms of metabolic equivalents of workload achieved, with endpoints being exercise-induced angina, fatigue, dyspnea, ST-segment changes, arrhythmias, and hypotension or hypertension.
The echocardiographic evaluation of right ventricular ejection fraction was based on pulsed-wave tissue Doppler imaging of the tricuspid annulus along with standard qualitative methods [12, 13]. The degree of pulmonary insufficiency was graded by a combination of semiquantitative and qualitative assessment.
Statistical Methods
Statistical analysis was performed using SPSS for Windows (Version 14.0; SPSS, Chicago, Illinois). Numeric variables were expressed in mean and standard deviation. The Fisher exact test was used to perform analysis of the variables, and the Wilcoxon signed rank test was used for nonparametric data. Kaplan-Meier analysis was utilized to compute probability of survival after surgery, with 95% confidence limits.
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Results |
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Nineteen patients (32.7%) had perioperative morbidity. Ten patients were reexplored for bleeding, all being patients operated on in the earlier part of our study. Right ventricular failure was present in 6 patients and necessitated prolonged inotropic support and hospital stay. One patient suffered a minor stroke postoperatively that resolved by the time of discharge. Two patients had pulmonary hemorrhagic complications after surgery due to bleeding from major aortopulmonary collaterals, for which both underwent coil embolization successfully. The patient with the value of 0.9 intraoperative ratio of right-to-left ventricular pressure had an uneventful recovery.
Three patients required readmission in the early follow-up period. A significant pleural effusion developed in 1, and 2 had features of early right ventricular failure, which responded to conservative measures.
Follow-up ranged from 15 months to 11 years, with a mean of 69.9 ± 43 months. Follow-up was 89% complete; 6 patients were lost to follow-up (Table 1). Late death occurred in 2 patients (3.7%), both with infective endocarditis, at intervals of 5 and 19 months after surgery. There were no reoperations in our study group for residual VSD, pulmonary regurgitation, right venticular failure, or residual gradient across the RVOT. One patient was reoperated on for infective endocarditis, but died a month after surgery.
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Comment |
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TopAbstractIntroductionPatients and MethodsResultsCommentAcknowledgmentsReferences |
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Delayed presentation of tetralogy of Fallot in adulthood could be due to either undiagnosed disease (primary delay) or delay in surgical repair (secondary delay). The primary delay subgroup includes patients with milder forms of the disease, those with development of natural collaterals, and those facing grass-root problems in the health care system [4]. The secondary delay group includes patients with a previous shunt procedure as well as those not able to afford surgery. In the Indian subcontinent, problems in the health tier system along with financial restrictions, poverty, and ignorance of the masses summate the delay in receiving appropriate surgical care.
The management of adult tetralogy is a surgical challenge due to the chronic multisystem cellular hypoxia and compensatory polycythemia, which predispose these patients to myocardial, neurologic, hematologic, and coagulation problems, as well as those related to the development of pulmonary collaterals [1–5]. The hypertrophied and fibrotic right ventricular myocardium is prone to myocardial dysfunction and to ventricular arrhythmias. As opposed to the pediatric population, this tendency is speculated to persist even after surgical repair in adulthood.
Older age has been considered an incremental risk factor for surgical repair, perioperative mortality, postoperative morbidity, and long-term survival [1, 6] and has formed the basis for certain groups to question the long-term benefits of surgery for this population [10]. Most reports confirm the high mortality among untreated patients [4, 5]. The majority of reports, to date, document the benefit of repairing adult tetralogy, especially with respect to improvements in functional class and long-term survival, despite varying surgical mortality rates [1–5].
In our study, we have found a statistically significant improvement in postoperative functional class at long-term follow-up (p < 0.001), with the majority of patients resuming vocation postoperatively. As regards the long-term survival, a definite benefit in terms of probability of survival has been demonstrated in our study with respect to traditional outcomes with medical management alone [1, 10]. The actuarial survival at 15 years was 89%, almost comparable to the life expectancy of the general population.
Our hospital mortality of 6.9% reiterates that surgical repair can be carried out with limited mortality. Medical literature reports the mortality to be between 6% and 12% [1–7]. The hospital mortality rate has arguably come down over the years owing to better techniques of myocardial protection, postoperative management, and use of antifibrinolytics, and to an overall better understanding of the pathophysiology of the disease.
We had no reoperations for residual VSD, pulmonary regurgitation, right ventricular failure, or residual gradient across the RVOT. However, 1 patient was reoperated on for infective endocarditis, but died a month after redo surgery. The patients with the residual VSDs were asymptomatic for the same, had no limitation of activity, and the shunt in all of them was judged to be insignificant by echocardiography. Unlike certain groups, we did not do a pulmonary valve replacement [1]. However, 1 patient with severe PR was advised surgery but was not willing to undergo the same. If dysplastic valves were encountered with an adequate size annulus, we excised the valve, ensuring no residual RVOT obstruction. The free pulmonary regurgitation that is thought to occur is well tolerated by the right ventricle, which, subjected to long-standing hypertrophy, has developed adequate amount of endocardial fibrosis [12]. We did not incorporate a monocusp valve while using a transannular patch during repair, as we believe that the benefit is very short lived in a ventricle well conditioned to tolerate a moderate amount of pulmonary regurgitation. Besides this, the monocusp valve can, over a period of time, degenerate and with resultant calcification, give rise to some form of outflow obstruction.
The surgical strategies in this patient population revolve around adequate myocardial protection, meticulous closure of the VSD, use of antifibrinolytic drugs, and relief of RVOT obstruction. Residual VSDs with significant shunts are poorly tolerated in this subset. Playing a pivotal role is the amount of right ventricular muscle resected. At the one extreme, excessive resection more than relieves the RVOT obstruction but exposes the ventricle to increasing PR, while at the other extreme, too little resection limits the amount of regurgitation, leaving behind residual obstruction. We believe the essence of the repair, and of subsequent outcomes, lies in achieving this balance.
We found the need to reconstruct the outflow tract with a transannular patch in 75.8% of our patients. The reported incidence of repairs utilizing a transannular patch in surgical adult tetralogy series is much lower, varying between 30% and 59% [1, 2, 5]. Presbitero and associates [2] attributed the decreased need for a transannular patch in adults to the milder form of obstruction that is encountered in such patients. They also postulated that the PR on follow-up was often mild because of the fewer and smaller transannular patchs. Although John and coworkers [5] had reported overall use of a transannular patch in 49.5% of their patients, their usage of the same was as high as 74% during the last few years of the period of their study. In our study, we found that presentation in adulthood was not merely related to milder forms of the disease, but also to a combination of other factors, mentioned earlier in our discussion. The need for a transannular patch was governed by the adequacy of the native annulus as judged preoperatively and intraoperatively.
Nollert and associates [6] have reported use of a transannular patch to be associated with significantly worse operative and 1-year mortality as compared with those without a transannular patch. The free pulmonary regurgitation associated with a transannular patch is thought to cause ventricular dilation and hamper ventricular function, especially during exercise. The results of our study show no statistically significant difference in effort tolerance or significant PR postoperatively between patients receiving a transannular patch and an RVOT patch.
The role of surgery in decreasing arrhythmic foci postoperatively remains controversial. Gatzoulis and coworkers [11] reported that the incidence of ventricular arrhythmias and sudden death is related to the chronic ventricular volume overload denoted by QRS prolongation, especially if greater than 0.18 s. Untreated tetralogy patients are at a risk to develop arrhythmias, especially ventricular ectopic beats, and ventricular tachycardia. The ventriculotomy during repair itself is speculated to generate the same. In our series, all patients were in sinus rhythm, with frequent premature ventricular ectopics seen in 3 cases that were asymptomatic for the same. Prolongation of QRS longer than 0.1 s was identified in 11.1% of postoperative cases, but in none did it exceed 0.18 s.
The studies on the long-term outcomes of surgical correction of tetralogy in adulthood are limited with respect to interpretation of right ventricular function. Although postoperative functional class can provide an insight into the status of the right ventricular function, two-dimensional echocardiography traditionally has been inaccurate in assessing the same. Recent reports, however, have postulated improved assessment using pulsed-wave tissue Doppler imaging of the tricuspid annulus along with standard qualitative methods. Utilizing the same approach, we demonstrated right ventricular ejection fraction ranged from 38% to 73%, with an average of 54.8%. There was no statistical difference in the ejection fraction between patients receiving a transannular patch and those with an RVOT patch. Further, these results were in conjunction to those of the treadmill testing. The transannular patch group patient with fair exercise tolerance of 7 metabolic equivalents achieved on treadmill testing along with severe PR on echocardiography had a correspondingly low right ventricular ejection fraction of 38%.
A modality of objective assessment of right ventricular function and of functional improvement, considered more sensitive than subjective assessment and echocardiography, is the exercise tolerance test [1]. This concept of objectively testing right ventricular function in postoperative tetralogy patients is not new and has been coupled to other assessment modalities. From the early 1970s through to the late 1990s, reports compared exercise tolerance in heterogeneous group of postoperative subjects with that of control groups [14–17]. Most investigators, however, did not assess either the outcomes of a transannular patch with respect to an RVOT patch or the limits of effort tolerance in presence of PR [16]. Moreover, the patient cohort was varied, and none represented an exclusively adult population.
Wessel and associates [16] used graded workloads on a cycle ergometer to show that patients with normal heart size, absence of residual obstruction or VSDs, RVOT patch in place of transannular patch, and absence of significant PR had better effort tolerance. They purported that, although residual PR was better tolerated than residual obstruction, cautious use of a transannular patch would decrease the incidence of PR associated with it. In our study, however, we did not find any statistical difference between the effort tolerance of patients with a transannular patch and patients with an RVOT patch.
Gatzoulis and coworkers [15] used treadmill testing coupled with respiratory mass spectroscopy and echocardiography and proposed that after repair, "restrictive" right ventricular morphology reduced PR and, in turn, improved effort tolerance as compared with hearts with a postoperative "nonrestrictive" morphology. The authors believed that the preoperative pathophysiology predicted postoperative ventricular morphology. However, we believe that most of adult patients have the restrictive right ventricular morphology preoperatively; it is the overzealous resection of the hypertrophied myocardium that transforms them into nonrestrictive forms associated with severe PR and ventricular dilatation.
Most studies have shown an inverse relationship between maximal working capacity and age at surgical repair [14, 17]. More than half the patients in one study [14], with a mean age of 19.6 years at surgical repair, had preoperative palliative shunts, which we feel would affect ventricular function. We believe though early surgery produces the best results, repair in the adult population can be achieved with good results in terms of effort tolerance.
Traditionally, PR, besides being associated with right ventricular dilatation and reduced exercise capacity, is believed to increase the risk of arrhythmias [15]. The incidence of arrhythmias has been evaluated during the course of graded exercise testing. While some workers have shown that with increasing effort, latent arrhythmias may manifest and may be a marker for high risk of life-threatening arrhythmias [14], others have speculated that the high sinus rate under such conditions decreases the incidence of ectopy [16]. In our study, we did not find any arrhythmias in our patients subjected to treadmill testing.
Limitations
We believe that only time will reveal the final outcomes of surgery in the adult population with tetralogy of Fallot. Longer periods of follow-up with periodic treadmill testing may help us understand the right ventricular function better. Another limitation of our study is the smaller numbers of patients with RVOT patch as compared with transannular patch, which may influence results. The semiquantitative assessment of PR after repair has also been a point of contention. The assessment of right ventricular function has been carried out on basis of exercise testing and right ventricular ejection fraction as measured by echocardiography. The limitation of these investigations to be representative of ventricular function is debatable. More advanced imaging techniques such as radionucleide-gated exercise scans and cardiac magnetic resonance imaging may provide a better insight into right ventricular function and hence long-term outcomes.
In conclusion, complete intracardiac repair of Tetralogy of Fallot with transannular patching in adults can be achieved with acceptable morbidity and mortality. Good long-term surgical outcome in terms of effort tolerance can be demonstrated by treadmill testing. Transannular patching does not appear to be a significant risk factor for right ventricular failure at long-term follow-up after surgical repair in the adult population.
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Acknowledgments |
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TopAbstractIntroductionPatients and MethodsResultsCommentAcknowledgmentsReferences |
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References |
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TopAbstractIntroductionPatients and MethodsResultsCommentAcknowledgmentsReferences |
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