Author + information
- Received October 30, 1997
- Revision received June 8, 1998
- Accepted June 17, 1998
- Published online October 1, 1998.
- Peter Munkhammar, MDa,
- Shay Cullen, MRCPc,
- Peeter Jögi, MDb,
- Marc de Leval, MD, FRCSd,
- Martin Elliott, MD, FRCSd and
- Gunnar Norgård, MD, PhDa,* ()
- ↵*Address for correspondence: Dr Gunnar Norgård, Department of Pediatrics, 5021 Haukeland Hospital, N-5021 Bergen, Norway
Objectives. To assess diastolic right ventricular (RV) physiology after tetralogy of Fallot repair in infancy.
Background. Restrictive RV physiology after tetralogy of Fallot repair is related to type of repair, pulmonary regurgitation, and late arrhythmias.
Methods. Forty-seven patients were investigated, 27 and 20 patients in Lund and London, respectively. Median age at repair was 0.78 years (0.08–0.99) and median follow-up was 3.0 years (0.08–10.4). Restrictive RV physiology was assessed by Doppler echocardiography.
Results. Thirteen patients (28%) had restrictive RV physiology at follow-up, three of 19 patients (16%) with transatrial repair and 10 of 28 patients (32%) with transventricular repair, respectively (p = 0.1). Ten percent of the patients repaired before 6 months of age were restrictive at follow-up, increasing to 38% with repair after 9 months. Transannular patch (TAP) repair was performed in 55% of the patients, including eight of 10 patients (80%) with repair before 6 months of age. Thirty-one percent of the patients with TAP repair were restrictive. These restrictive patients had more severe preoperative pulmonary stenosis (p < 0.05), were older at repair (p < 0.05), and had shorter duration of pulmonary regurgitation (p < 0.001) at follow-up.
Conclusions. Restrictive RV physiology is inversely related to age at repair and independent of type of outflow tract repair. Since TAP repair is more common in early repair, and restriction seems to be less frequent, long-term follow-up to assess adverse effects of pulmonary regurgitation is mandatory.
Excellent early results are expected after repair of tetralogy of Fallot (TOF) in the current era (1). However, residual defects are common and affect the long-term outcome (2–4). The implements of pulmonary regurgitation (PR) on long-term outcome has until recently been controversial, although its deleterious effects on exercise performance, right ventricular (RV) volume, and late arrhythmias are now accumulating (5–8).
The concept of restrictive RV physiology has recently been determined after repair for TOF (9). The beneficial effect of restrictive RV physiology on long-term outcome is well established (10). It is not known, however, if restriction is related to the TAP repair per se, the RV scarring, or other factors. In a recent TOF study, we found restrictive RV physiology to be common in children after transannular patch (TAP) repair beyond infancy (11). Since the need for and the use of TAP is known to be more common when surgery is done in early infancy, it seems mandatory to assess the subsequent RV physiology after repair in these patients.
With the aim of reducing RV scarring and improve the long-term outcome, transatrial repair has been reintroduced recently (12–15). However, the possible impact of transatrial repair on subsequent restrictive RV physiology has not been studied in detail.
The purpose of the present study was: 1) to assess RV diastolic physiology in TOF patients repaired in early infancy, and 2) to relate this physiology to age at repair and surgical technique.
Forty-seven patients, 31 boys and 16 girls, repaired for TOF in early infancy between 1985 and 1996, 27 at Lund and 20 at Hospital for Sick Children (London, UK), participated in a mid-term follow-up study. Patients with double-outlet right ventricle, TOF with absent pulmonary valve, pulmonary atresia with ventricular septal defect (VSD), and aortic pulmonary collateral’s and TOF in combination with atrioventricular septal defects were excluded from the study. Forty-five TOF patients repaired in Lund from 1985 to 1996 fulfilled our inclusion criteria. Twenty-seven patients (60%) were eligible for the follow-up study, including 18 patients repaired after 1990. Eighteen patients (40%) were followed elsewhere and did not participate in the study. Forty patients were repaired at the Hospital for Sick Children from 1994 to 1996. Private patients and patients from abroad were not included. Twenty of these (50%) consented to participate in the study. All patients were examined by two-dimensional, M-mode and Doppler echocardiography and a 12-lead standard electrocardiogram. Informed consent was obtained from all parents and the study protocol was approved by the ethical committee at the Hospital for Sick Children.
Clinical information including medical history, previous echocardiography, cardiac catheterization, and surgical data were collected from the medical notes according to our protocol. Echocardiography was performed with Acuson 128 (Lund) and Acuson XP10 using 3.5- or 5.0-MHz transducers.
A complete echocardiographic study was performed by an experienced pediatric cardiologist (PMU, SC, GN) in all patients. Three to five consecutive heart beats and three heart beats were analyzed from the right and left heart recordings, respectively (9,11).
Two-dimensional and M-mode echocardiography
Left ventricular dimensions at end-diastole and end-systole were measured in a standardized way from parasternal long- or short-axis views (9,11). End-diastole were defined as the start of the Q-wave on the electrocardiogram.
Doppler echocardiography: AV valves
E- and A-wave velocities (m/s) and E-wave deceleration time (ms) were obtained with the sample volume at the tips of the atrioventricular (AV) valves by pulsed Doppler echocardiography using the apical four-chamber view (9,11).
Continuous-wave Doppler was used to assess residual pulmonary stenosis. Patients with a gradient of more than 40 mm Hg using the simplified the Bernoulli equation were excluded from further analysis. Pulsed-wave Doppler with the sample volume between the leaflets and pulmonary artery bifurcation were used to interrogate restrictive RV physiology defined as antegrade pulmonary artery (PA) flow in late diastole throughout the respiratory cycle or in five consecutive beats. Velocities of PA systolic and diastolic forward flow (a-wave) and duration of pulmonary regurgitation were measured from the same recordings.
Resting 12-lead electrocardiogram (ECG) was obtained in all patients using a Siemens Elema Megacart system. QRS duration was measured from the first to the last deflection from the isoelectric line, and the longest measurements in any lead were used for analysis (4).
Cardiopulmonary bypass with moderate hypothermia, aortic crossclamping, and cold crystalloid cardioplegic arrest were employed on all patients irrespective of approach.
An incision was made in the right ventricle and the ventricular septal defect (VSD) was closed through the ventriculotomy. Through the same incision, obstructing bundles in the RV outflow tract (RVOT) were excised. When the pulmonary valve (PV) annulus was considered to be too narrow, the incision was extended through the pulmonary annulus into the main PA and a TAP using autologous pericard was inserted. If the PV annulus was of sufficient size, a valvotomy was performed and a subvalvar outflow patch was inserted, avoiding the pulmonary valve annulus.
An incision was made in the right atrium and the VSD was closed with a patch through the tricuspid valve. Valvotomy of a stenotic PV was performed through the pulmonary trunk. If enlargement of the PV annulus was required, the pulmonary incision was extended for a short distance across the valve ring into the RV outflow tract and the outflow was enlarged with a transannular patch.
Data are presented as mean (±SD) or median with range. Comparison between groups was by Student’s t-test or Mann Whitney U test, when appropriate. The normality of the data was assessed by Kolmogorow-Smirnow test. Chi square test of Fisher exact test were used to assess group differences for categorical variables. The null hypothesis was rejected when p <0.05.
Surgical and postoperative data
Thirteen patients (28%) received a modified Blalock-Taussig-shunt prior to repair. Transatrial repair was performed in 19 patients (40%) and transventricular repair in 28 patients (60%) (Table 1). Patients with transventricular repair had longer follow-up then transatrial repaired patients (4.6 ± 2.9 vs. 1.7 ± 2.3 years, respectively, p < 0.001). Both groups where repaired at the same age. Transatrial repair was significantly more common with repair before 6 months of age (0.70 ± 0.22 and 0.66 ± 0.28 years, respectively, p < 0.05). Twenty-six patients (55%) had TAP repair with a tendency to be more common in patients repaired before 6 months of age (p = 0.08) (Fig. 1).
Restrictive versus nonrestrictive RV physiology
Preoperative and surgical characteristics
Preoperative peak pressure gradients across the RVOT was 76.2 ± 18.2 and 68.7 ± 18.4 mm Hg in restrictive and nonrestrictive patients, respectively (NS). Patients with restrictive RV physiology were significantly older at repair as compared with nonrestrictive patients (Table 1). Three patients (16%) with transatrial repair were restrictive at follow-up, compared with 10 patients (36%) with transventricular repair (p = 0.13). Restrictive RV physiology was less common with repair before 6 months of age (p = 0.12). (Fig. 1).
PR duration was significantly shorter in restrictive patients (Table 2). No other differences were found between restrictive and nonrestrictive patients.
Echocardiographic data in patients with transannular patch repair
RV outflow tract repair was not related to subsequent restrictive RV physiology (Fig. 2). Preoperative pulmonary stenosis was more severe, the patients were older at repair, and pulmonary regurgitation was shorter in restrictive patients in comparison with nonrestrictive patients (Table 3).
ECG at follow-up
QRS duration immediately after repair or at follow-up did not differ significantly between the restrictive and the nonrestrictive group. QRS duration was 101.4 ± 25.4 and 122.1 ± 24.2 ms after transatrial and transventricular repair, respectively (p <0.01).
In the present study, 28% of the patients repaired in early infancy had evidence of abnormal RV diastolic function at mid-term follow-up. In previous studies, 38–52% of the patients demonstrated restrictive RV physiology early and late after repair. In these studies, the patients were repaired beyond infancy and the majority by a transventricular approach. We therefore speculate that age at repair and surgical approach may be important factors related to development of restrictive RV physiology.
Determinants for restrictive RV physiology
Preoperative factors and surgical characteristics
In this study, we focused on age at repair and its possible association to later diastolic RV physiology. Based on our previous research (10,11), we were concerned that early TAP repair could have deleterious effects on later RV function, given the common use of TAP repair in infancy (16,17)and a potential for less RV restriction.
Preoperative pulmonary stenosis
Restrictive patients in the present study had a tendency for more severe pulmonary stenosis (PS) prior to repair, and they were significantly older at repair. Furthermore, in restrictive patients with TAP repair, PS was significantly more severe, and these patients were also older at repair. This is in agreement with our recent report, also showing more severe PS prior to repair in patients with subsequent restrictive RV physiology (11). Age at repair and development of more severe PS are closely related. We believe our findings reflects the anatomical substrate for restriction, which do not seem to be independent of age. Right ventricular pressures are systemic in TOF patients regardless of pulmonary stenosis. Shunting across the VSD is dependent on several factors where resistance to pulmonary and systemic flow, anatomy of the pulmonary valve stenosis, and infundibulum are contributing. There is an evolution of RV hypertrophy with time, which may be triggered by other factors than degree of pulmonary stenosis. We may speculate that long-lasting combined RV hypertrophy and hypoxia may form the substrate for later restrictive RV physiology. Of these two factors, hypertrophy secondary to more severe PS seems to be most important, since the preoperative oxygen saturation was similar in restrictive and nonrestrictive patients. However, the different number of patients with Blalock-Taussig shunt in restrictive and nonrestrictive patients do not allow us to draw conclusions on possible relations between oxygen saturation and restriction. It has been stated by Casteneda et al. (18)that more extensive infundibular resection is demanded in older patients with more severe RV hypertrophy. This could also be a contributing factor for later restriction by increasing the scarring in the RV outflow tract. However, in the present report, we have no data to support this possible mechanism.
Transannular patch repair
In this study we found restrictive RV physiology in 31% of the patients with TAP repair, and TAP repair was not an independent factor for later restriction. Of interest, 80% of the patients with repair before 6 months of age had a TAP repair and only one of these patients demonstrated later restrictive RV physiology. This contrasts with our recent study (11), where we demonstrated a close association between restrictive RV physiology and TAP repair. However, our suggestion was that the need for a TAP repair, rather than the TAP itself, was responsible for later restriction. The most striking difference between these two studies is age at surgical repair. Although the number of patients with very early repair was limited in the present study, our data suggest that age at repair is one important factor related to restrictive RV physiology.
Transatrial versus transventricular repair
In our study transatrial repair was significantly more common (70%) before 6 months of age, and none of these patients had subsequent restrictive RV physiology. A tendency for less restriction after transatrial repair was observed in the present study. Of interest, the restrictive patients were repaired at age 8.6–11.4 months. To our knowledge, only one previous study has addressed transatrial repair and restrictive RV physiology (15). Atallah-Yunes et al. (15)found RV restriction to be independent of transatrial or transventricular repair. However, in their study the patients were older at repair and the restrictive RV physiology may reflect age at repair rather than type of repair. Furthermore, their definition of restrictive RV physiology was not clear from the paper. Transatrial repair have been recommended recently, and excellent early and mid-term results have been achieved (15,19). In a study by Stellin et al. (14), comparing transatrial and transventricular repair, they suggested RV function to be superior after transatrial repair. However, the patients with transatrial repair had shorter follow-up. Of more importance, they based their conclusions on echocardiographic RV volume measurements, which are known to be inaccurate (20,21). Therefore, their conclusions may not be valid. In our study, patients with transatrial repair also had shorter follow-up. Thus, some of the same limitations apply to our study as well. However, we have not based our conclusions on volume measurements but on the presence or absence of restrictive RV physiology as assessed by Doppler echocardiography. Although this report is from two cardiac centers, we are familiar with the Doppler assessment of diastolic RV physiology, and use strict and uniform criteria’s for obtaining and analyzing the Doppler data.
In the present study QRS duration did not differ between restrictive and nonrestrictive patients with TAP repair. This seems to be in contrast to our recent study, where early QRS prolongation was found in nonrestrictive patients with TAP repair (11). However, in the present study the small number of patients with restrictive RV physiology and the short follow-up prevents us from drawing conclusions regarding early QRS prolongation. Interestingly, we found QRS duration to be significantly shorter in patients with transatrial repair. The follow-up was however, significantly longer in patients with transventricular repair. Nonetheless, since TAP was common and restriction uncommon with transatrial repair, QRS prolongation could be present even at short-term follow-up, as we have shown in a recent study (10). We may speculate that this reflects favorable details in the surgical technique with less extensive muscular resection, more valve sparing even when a TAP is used, and subsequently less pulmonary regurgitation. However, longer follow-up including assessment of RV size, and QRS duration is needed to validate these data.
Doppler data and restrictive RV physiology
Our findings of shorter duration of pulmonary regurgitation in restrictive patients are in agreement with previous studies (8–10). In this study we have assessed duration of PR regurgitation from the same Doppler recording as we use to define restriction. Given the same heart rate and the same degree of PR, the duration of PR will be shorter in the restrictive patients. Theoretically, shorter PR duration could be possible in nonrestrictive patients if these patients had less PR. Duration of PR is shortened in restrictive patients with forward flow in the pulmonary artery in late diastole. This reflects the time available for PR to occur, and therefore probably reflects less PR in restrictive patients. In fact, this assumption is supported by the fact that restrictive patients in previous studies had smaller hearts (9). Ticuspid E-wave deceleration time was not significantly shorter in restrictive patients in the present study. This contrasts with previous studies in older patients (8,10). However, given the methodological limitation of tricuspid valve Doppler measurements in young patients with fast heart rates, this finding is not surprising.
Limitations of the study
This report is a combined study from two cardiac centers with three surgeons responsible for the surgical repair. Strict uniform criteria for timing of repair, type of repair, and the use of TAP repair do not exist. The surgical treatment may therefore be slightly different in the two centers. Furthermore, the London study reports patients with more recent surgery and shorter follow-up. The Lund patients were repaired by one surgeon. The study was not primarily designed to compare transatrial and transventricular repair, but to assess RV physiology in relation to age at repair. A larger number of patients with early repair will be needed to address the relative contribution of age at repair, type of repair, and later RV function. With these limitations in mind, we still believe the results to be valid and in line with the purpose of the study.
Restrictive RV physiology seems to be less common with TOF repair in early infancy and independent of type of outflow tract reconstruction. Since restrictive RV physiology may produce a better long-term result by minimizing PR, it is mandatory to include assessment of restrictive RV physiology in further studies.
- pulmonary artery
- pulmonary regurgitation
- pulmonary valve
- right ventricle
- right ventricular outflow tract
- transannular patch
- tetralogy of Fallot
- ventricular septal defect
- Received October 30, 1997.
- Revision received June 8, 1998.
- Accepted June 17, 1998.
- American College of Cardiology
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