Author + information
- Received November 4, 1999
- Revision received March 30, 2000
- Accepted June 2, 2000
- Published online October 1, 2000.
- ↵*Reprint requests and correspondence: Dr. Tal Geva, Department of Cardiology, Children’s Hospital, 300 Longwood Avenue, Boston, Massachusetts 02115
This study sought to determine the diagnostic accuracy and impact of the systematic use of coronary echocardiography in a large group of preoperative patients with tetralogy of Fallot (TOF).
Accurate preoperative identification of an anomalous coronary artery crossing the right ventricular outflow tract (RVOT) in patients with TOF is important to prevent coronary injury during surgical repair.
A retrospective review identified 598 patients with TOF between 1983 to 1995 who underwent an echocardiogram at <2 years old before complete surgical repair. Associated diagnoses included pulmonary stenosis (n = 433), pulmonary atresia (n = 121), common atrioventricular canal (n = 17), absent pulmonary valve syndrome (n = 24) and aortopulmonary window (n = 3).
Based on intraoperative findings, 32 patients (5.4%) were found to have a major coronary artery crossing the RVOT. The use and diagnostic performance of coronary echocardiography increased over time, while the number of patients undergoing preoperative cardiac catheterization declined. During the most recent study period (1991 to 1995, n = 274), 97% of patients underwent coronary echocardiography yielding a sensitivity of 82%, specificity of 99% and accuracy of 98.5%. Of the 18 patients with TOF and pulmonary stenosis who had abnormal coronary arteries during this period, only 6 (33%) required an extracardiac conduit as part of their complete repair.
Coronary echocardiography is an accurate noninvasive tool to delineate coronary anatomy in infants with TOF before complete repair. Routine preoperative cardiac catheterization solely for diagnosis of coronary anatomy is not necessary. The use of an extracardiac conduit can be avoided in the majority of patients with TOF and pulmonary stenosis who have a major coronary artery crossing the RVOT.
Accurate preoperative evaluation of coronary anatomy in patients with tetralogy of Fallot (TOF) is essential for a successful surgical repair. Approximately 5% of patients with TOF will have an anomalous coronary artery crossing the right ventricular outflow tract (RVOT), potentially complicating the infundibulotomy (1–4). It remains common practice in many centers for all patients with TOF to undergo routine preoperative cardiac catheterization, with delineation of coronary anatomy being cited as one of the indications for this practice (5,6). Coronary echocardiography has played an increasing role in the preoperative evaluation of other forms of congenital heart disease, such as transposition of the great arteries (7) or anomalous origin of the left coronary artery (LCA) from the main pulmonary artery (8). Two small prospective studies in patients with uncomplicated TOF demonstrated that two-dimensional echocardiography is accurate in delineating the preoperative coronary anatomy (3,4). Moreover, both Santoro et al. (9) and Saraclar et al. (10) found that echocardiography can be used as the sole preoperative diagnostic test for patients with TOF. These studies, however, were limited by the small number of patients with an anomalous course of a coronary artery crossing the RVOT and by the exclusion of patients with complex TOF, such as TOF with pulmonary atresia and TOF with common atrioventricular (AV) canal. Moreover, the implications of anomalous coronary pattern for surgical management of TOF have remained unclear. Several centers have advocated a staged approach in these patients, in which an aortopulmonary shunt is placed in infancy with subsequent placement of an extracardiac conduit between the right ventricle and pulmonary artery as part of a complete repair (11–13). The purpose of this study was to determine the diagnostic accuracy of the systematic use of coronary echocardiography in a large patient population with all forms of TOF, to examine its impact on the use of preoperative diagnostic catheterization and to evaluate the effects of anomalous coronary patterns on current surgical outcome.
The computer database of the Department of Cardiology at Children’s Hospital, Boston, was searched for all patients with TOF who had undergone surgery between January 1983 through December 31, 1995. Inclusion criteria to this study were: 1) a preoperative echocardiogram performed at Children’s Hospital before the age of 2 years, and 2) no previous cardiac surgery except for placement of an aortopulmonary shunt. Patients with all variants of TOF were included in this study, including TOF with pulmonary stenosis (TOF/PS), TOF with pulmonary atresia, TOF with common AV canal, TOF with absent pulmonary valve syndrome and TOF with aortopulmonary window.
Patients’ variables included demographic information, age and body surface area at preoperative echocardiography, preoperative cardiac catheterization and surgical repair. All echocardiogram, catheterization, operative and autopsy reports were reviewed for descriptions of coronary anatomy. The branching pattern of the coronary arteries was determined in each patient by direct visualization at the time of surgery and was considered the “gold standard” to which the diagnoses by echocardiography and catheterization were compared. All echo reports were issued before catheterization or corrective surgery were performed. Operative reports were also evaluated with respect to the type of surgical approach used. Patients were grouped according to the presence or absence of a major coronary artery branch crossing the RVOT. In this study a major coronary artery abnormality was defined as either the left anterior descending coronary (LAD) arising from the right coronary artery (RCA) and reaching the anterior interventricular groove or origin of the RCA arising from the LAD. The anatomy of coronary artery branching was classified into one of the following patterns (Fig. 1): 1) normal, 2) normal but with a large conal branch that does not reach the anterior interventricular groove, 3) LAD arising from the RCA, 4) dual LAD, 5) single RCA, and 6) single LCA.
Patients were divided into three chronological groups to evaluate changes in the use and accuracy of coronary echocardiography over time: group 1, 1983 to 1986; group 2, 1987 to 1990 and group 3, 1991 to 1995. These time intervals were also used to determine the number of patients who underwent surgery based on echocardiography alone. The implications of coronary echocardiography and abnormal coronary patterns on surgical management and outcome were examined in patients with TOF/PS for the period of 1990 through 1995. Only the most recent period was selected because it represents current surgical management. Patients with TOF and pulmonary atresia were not included in the analysis since the majority of these patients received a conduit between the right ventricle and the pulmonary artery, regardless of the pattern of coronary artery branching. Follow-up data was obtained on the 18 patients with TOF/PS who had abnormal coronary anatomy. This group was compared with 28 patients (control group) randomly selected from the remaining 220 patients from the same chronological and anatomic group. Patients in the control group were matched to patients with abnormal coronary pattern based on length of follow-up. The groups were compared with respect to the degree of RVOT gradient at follow-up, reoperations, interventional catheterizations and mortality.
As part of the inclusion criteria, all patients had a complete preoperative echocardiographic study performed. The results, as detailed in the formal echocardiography report, were used for data analysis. The techniques used to examine coronary anatomy in the Echocardiography Laboratory at Children’s Hospital, Boston, have been reported (14,15). Briefly, the coronary arteries were examined primarily from the parasternal short- and long-axis views. From the parasternal short-axis view, the left main coronary is imaged as it originates from the aortic left sinus of Valsalva. Clockwise rotation of the transducer with a slight apical angulation then profiles the LAD as it courses toward the anterior interventricular groove and also depicts the origin of the left circumflex coronary. The RCA is imaged from a slightly higher parasternal short-axis view with particular attention to the size and extent of the conal branch. Anomalous origin of the LAD from the RCA can be seen from this view by following the coronary artery that originates from the proximal RCA to the anterior interventricular groove and excluding origin of the LAD from the left main coronary artery (Fig. 2A). From the parasternal long-axis view, the left main, LAD and circumflex coronaries are imaged at a plane between the aortic root and the main pulmonary artery. From these views, the infundibular free wall is examined for evidence of a blood vessel coursing its epicardial surface (Fig. 2B)(3,4). Additional information can be obtained from oblique low parasternal and apical views as well as from the subxiphoid window. Every effort is made to optimize coronary imaging by suppressing spurious signals (lower gain and compress settings) and by using the highest frequency transducer possible to maximize spatial resolution. Sedation with oral chloral hydrate is used in infants between two and three weeks and two years according to a published protocol (15).
Normally distributed continuous data are expressed as mean value ± standard deviation. Nonnormally distributed continuous data are expressed as median values. The sensitivity, specificity, accuracy and positive and negative predictive values of coronary echocardiography as compared with intraoperative observations were determined according to standard definitions (16). The significance of differences between groups in categorical variables was evaluated using the chi-square test. The significance of differences between median values of multiple groups was tested using the Kruskal-Wallis test followed by the Dunn procedure for multiple comparisons. The Wilcoxian rank-sum test was used to evaluate the significance of differences in median values of two groups, and the two-tailed unpaired Student t test was used to compare means for normally distributed data. A p value <0.05 was considered statistically significant.
A total of 598 patients met inclusion criteria for this study. Their characteristics are summarized in Table 1. Tetralogy of Fallot/pulmonary stenosis was the most common anatomic diagnosis (n = 433, 72%) followed by TOF with pulmonary atresia (n = 121, 20%), TOF with common AV canal (n = 17, 3%), TOF with absent pulmonary valve syndrome (n = 24, 4%) and TOF with aortopulmonary window (n = 3, 1%). Gender, mean age and body surface area at the time of the initial echocardiogram were not significantly different among the anatomic groups. The only group that had a significantly older age at surgical repair was the patient group with TOF associated with common AV canal (p < 0.001). Both the patients with associated pulmonary atresia and those with associated common AV canal were more likely to have undergone previous placement of an aortopulmonary shunt than patients with TOF and PS (p < 0.001). Almost all shunt procedures, however, were performed at other institutions before definitive repair at Children’s Hospital.
Based on intraoperative findings, a total of 32 patients (5.4%) were found to have a major coronary artery crossing the RVOT. Eighteen patients had an anomalous origin of LAD from the RCA; 11 patients had dual LADs; 2 patients had a single RCA, and 1 patient had a single LCA (Table 2). A coronary to pulmonary artery fistula was diagnosed by echocardiography in two patients. All of the patients with coronary anomalies had either TOF/PS (n = 23, incidence 5.3%) or TOF with pulmonary atresia (n = 9, incidence 7.4%).
Use and accuracy of coronary echocardiography
Performance of coronary echocardiography in patients with TOF increased over the study period: 39% (44 patients) in 1983 to 1986, 93% (198 patients) in 1987 to 1990 (p < 0.001) and 97% (265 patients) in 1991 to 1995 (p = NS compared with the second period, p < 0.001 compared with the initial period) (Fig. 2). For studies in which coronary echocardiography was attempted, technical difficulties prevented a complete evaluation in 14% of patients for 1983 to 1985, 4% for 1986 to 1990 (p = 0.004) and 3% for 1991 to 1995 (p = NS compared with the second period, p < 0.001 compared with the initial period).
The sensitivity, specificity, positive and negative predictive values and accuracy of coronary echocardiography in detecting a major coronary artery crossing the RVOT as compared with the surgical findings are summarized in Table 3. During the study period, the sensitivity and positive predictive value of coronary echocardiography in detecting coronary arteries crossing the RVOT increased, especially when compared with the 1983 to 1986 period. The performance characteristics of coronary echocardiography in the most recent study period (1991 to 1995) had a sensitivity of 82%, specificity of 99% and an accuracy of 98.5%. The specificity, negative predictive value and accuracy remained high throughout the study period.
Of the 274 patients in the most recent group (1991 to 1995), 18 patients were found by intraoperative inspection to have a major coronary artery crossing the RVOT. Echocardiography failed to correctly identify the anomalous coronary in three cases. Of these, one patient underwent preoperative catheterization, at which time the coronary anomaly was diagnosed. The other two patients had echocardiograms that the interpreting cardiologists deemed technically limited with an equivocal coronary evaluation. After discussion with the referring cardiologists and cardiac surgeons involved in their care, neither of these patients underwent preoperative catheterization. In both cases, careful intraoperative inspection diagnosed the coronary anomalies.
Use of cardiac catheterization
Over the 13-year study period, the proportion of patients undergoing diagnostic preoperative cardiac catheterization decreased from 89% (100 patients) in 1983 to 1986 to 69% (147 patients) in 1987 to 1990 (p < 0.001) and then to 27% (73 patients) in 1991 to 1995 (p < 0.001 compared with both earlier periods) (Fig. 3). Coronary angiography, however, was not performed in every patient who underwent cardiac catheterization. Coronary anatomy was evaluated during these catheterizations (either by aortic root angiography or selective coronary angiography) in 86% of patients in 1983 to 1986, 90% in 1987 to 1990 and in only 60% in 1991 to 1995 (p < 0.001 compared with both earlier periods).
Cardiac catheterization was performed more frequently in patients with TOF and pulmonary atresia (94/121, 77%) compared with those with TOF/PS (206/433, 48%) (p < 0.001). Over the 13-year study period, the frequency of cardiac catheterization in patients with TOF/PS decreased from 90% in 1983 to 1986 to 65% in 1987 to 1990 (p < 0.001) and then to 18% in 1991 to 1995 (p < 0.001). In patients with TOF and pulmonary atresia, the frequency of cardiac catheterization decreased from 96% in 1983 to 1986 to 86% in 1987 to 1990 (p = NS), to 58% in 1991 to 1995 (p < 0.001). Of those patients with TOF/PS who underwent cardiac catheterization, 90% (186) had the question of coronary anatomy addressed. In contrast, coronary angiography was attempted in only 53% of patients with TOF and pulmonary atresia.
The proportion of patients undergoing surgical repair of TOF based on echocardiographic evaluation alone increased during the study period from 11% (12/112 patients) in 1983 to 1986 to 31% (66/213 patients) in 1987 to 1990 to 73% (200/273 patients) in 1991 to 1995 (p < 0.001). Figure 4 shows the frequency of surgery based on echocardiography alone during the study period for patients with TOF/PS and those with pulmonary atresia.
Because the majority of patients with TOF and pulmonary atresia are repaired using a right ventricle to pulmonary artery homograft, regardless of coronary artery anatomy, the surgical implications of anomalous coronary branching is most relevant in patients with TOF/PS. Of the 238 patients with TOF/PS diagnosed in 1990 to 1995, 18 patients (7.6%) were identified as having an anomalous coronary artery crossing the RVOT. The surgical procedures performed on these patients are summarized in Table 4. The age of surgical repair in patients with anomalous coronary arteries was similar to that in patients with normal coronary pattern (5.3 ± 0.8 vs. 5.7 ± 0.4, p = NS). Only six patients (33%) required an extracardiac conduit as part of their surgery. Of the seven patients with dual LAD coronary arteries, five had repair with an RVOT patch (three transannular, two nontransannular); one had a transatrial approach to avoid the anomalous coronary artery, and one had placement of an extracardiac conduit during the same operation after a transatrial approach failed to adequately relieve the RVOT obstruction. Of the 10 patients with the LAD arising from the RCA, three had a nontransannular RVOT patch placed below the anomalous coronary artery, two had a transatrial repair to avoid the anomalous coronary artery, and five required placement of an extracardiac conduit. In two of the five patients who received an extracardiac conduit, an attempt was first made to relieve the RVOT obstruction without a conduit. The patient with a single RCA underwent repair with a transannular RVOT patch.
Follow-up data for the 18 patients with TOF/PS and an anomalous coronary artery pattern were compared with 28 contemporary patients with normal coronary arteries. At a median follow-up period of 8.3 months, the Doppler maximal instantaneous gradient across the RVOT in patients with anomalous coronary branching was 22 ± 29 mm Hg compared with 10 ± 16 mm Hg in controls (p = 0.09). Among the 12 patients with anomalous coronaries who underwent surgical repair without a conduit, none required reoperation, and there was no significant difference in either the total number of procedures or the number of RVOT procedures when compared with control patients.
Of the 598 patients included in this study, 22 patients (3.7%) died before discharge from the hospital after surgical repair. As shown in Table 1, patients with associated pulmonary atresia had a significantly higher mortality rate. Over time, there was a decrease in mortality from 7% (8/112 patients) in 1983 to 1986 to 4% (9/212 patients) in 1987 to 1990 (p = NS), to 2% (5/274 patients) in 1991 to 1995 (p < 0.05 compared with the 1983 to 1986 group). Of the 32 patients who had an anomalous coronary artery crossing the RVOT, only one patient (3%) died before discharge from the hospital (p = NS compared with patients with normal coronary arteries). That patient’s death was due to E. coli sepsis.
The results of this study indicate that echocardiography is an accurate noninvasive tool in the delineation of coronary anatomy as part of a comprehensive preoperative assessment of infants with all forms of TOF. During the 13-year study period, the utilization of coronary echocardiography increased, and its diagnostic performance improved. Coinciding with these developments, the use of preoperative diagnostic cardiac catheterization decreased, and the proportion of infants undergoing complete surgical repair based on echocardiography alone increased from 11% in 1983 to 1986 to 73% in 1990 to 1995 (82% for TOF/PS). From the surgical standpoint, in two-thirds of infants with TOF/PS and a major coronary artery crossing the RVOT, conduit placement was avoided with excellent hemodynamic results.
Diagnostic accuracy of coronary echocardiography
Previous investigations of the accuracy of coronary echocardiography in TOF demonstrated encouraging results. Studies by Berry et al. (3), Jureidini et al. (4), as well as a larger study by Santoro et al. (9), were limited by the small number of patients with anomalous coronary arteries and by exclusion of patients with complex TOF. In contrast, this study includes 598 patients with all forms of TOF, 32 of whom had a major coronary artery crossing the RVOT. In this patient population, the systematic use of coronary echocardiography as a routine component of the preoperative echocardiogram yields a reasonable diagnostic profile with 82% sensitivity, 99.6% specificity, 93% positive predictive value, 99% negative predictive value and 98.5% accuracy.
The results of this study indicate that preoperative diagnostic catheterization solely for assessment of coronary anatomy is not routinely indicated. This conclusion is supported by the dramatic decrease over time in the number of patients undergoing preoperative diagnostic catheterization shown in this study, with a concurrent decrease in mortality. Clearly, there are other indications for a preoperative diagnostic catheterization for which echocardiography is less well suited, such as assessment of the distal pulmonary arteries and aortopulmonary collaterals. This is illustrated in this study by the higher rate of preoperative diagnostic catheterization in patients with TOF and pulmonary atresia compared with those with TOF/PS. It is worth noting that, despite the greater use of catheterization in these patients, a lower percentage (53% vs. 90% in patients with TOF/PS) had the question of coronary anatomy addressed at the time of their catheterization.
Current practice at our institution is to delineate the coronary anatomy by echocardiography. If the echocardiographic diagnosis is felt to be equivocal, the surgeon is alerted and is prompted to carefully examine the proximal coronary arteries. Coronary angiography is rarely the primary indication for cardiac catheterization in patients with TOF.
A prerequisite for the success of coronary echocardiography as the sole preoperative study is excellent communication between the surgeon and echocardiographer. Patients with technically suboptimal coronary echocardiography must be identified and discussed with the surgeon. This information is relevant for the discussion of the surgical procedure with the parents and for surgical planning. Since current practice is to perform a primary complete repair in all forms of TOF, adhesions from previous palliative procedures that might otherwise hinder the surgeon’s ability to inspect the coronary arteries are rare. In such circumstances, the decision regarding the use of diagnostic tests in addition to echocardiography must be made on an individual basis. An emerging alternative to invasive coronary angiography in such patients is magnetic resonance angiography (17).
In this study, the presence of an anomalous coronary artery crossing RVOT did not necessitate the placement of an extracardiac conduit for relief of RVOT obstruction in the majority of patients with TOF/PS. In patients diagnosed in 1990 to 1995, the majority (86%) of patients with dual LAD and 50% of patients with a single LAD arising anomalously and crossing the RVOT did not require an extracardiac conduit as part of their surgical repair. Preoperative identification of coronary anomalies with careful intraoperative inspection can lead to alternative surgical approaches, including transatrial repair or placement of RVOT patch with a limited right ventriculotomy that preserves the anomalous vessel. Nonconduit approaches in patients with TOF/PS and anomalous coronary arteries did not lead to a higher degree of RVOT obstruction on short-term follow-up. Moreover, none of these patients required subsequent placement of an RVOT conduit if one was not placed as part of the initial repair.
Accurate delineation of coronary anatomy is feasible using echocardiography as the sole preoperative diagnostic study in patients with tetralogy of Fallot. Preoperative diagnostic cardiac catheterization for the purpose of addressing coronary anatomy is not necessary. Finally, placement of an extracardiac conduit can be avoided in the majority of patients with TOF/PS by the use of alternative surgical approaches with good clinical outcome.
We thank Emily Flynn McIntosh for artwork and Bill McIntosh for photography.
☆ Supported, in part, by the following grants: HL-46207 and NHLBI 2T32HL07527-123A.
- left anterior descending coronary artery
- left coronary artery
- pulmonary stenosis
- right coronary artery
- right ventricular outflow tract
- tetralogy of Fallot
- Received November 4, 1999.
- Revision received March 30, 2000.
- Accepted June 2, 2000.
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