Background
Management of right-dominant atrioventricular septal defect (AVSD) remains a challenge given the spectrum of ventricular hypoplasia. The purpose of this study was to assess whether reported echocardiographic indices and additional measurements were associated with operative strategy in right-dominant AVSD.
Methods
A blinded observer retrospectively reviewed preoperative echocardiograms of patients who underwent surgery for right-dominant AVSD (January 2000 to July 2013). Ventricular dimensions, atrioventricular valve index (AVVI; left valve area/right valve area), and right ventricular (RV)/left ventricular (RV/LV) inflow angle were measured. A second observer measured a subset of studies to assess agreement. Pearson correlation analysis was performed to examine the relationship between ventricular septal defect size (indexed to body surface area) and RV/LV inflow angle in systole. A separate validation cohort was identified using the same methodology (August 2013 to July 2016).
Results
Of 46 patients with right-dominant AVSD (median age, 1 day; range, 0–11 months), overall survival was 76% at 7 years. Twenty-eight patients (61%) underwent single-ventricle palliation and had smaller LV dimensions and volumes, AVVIs ( P = .005), and RV/LV inflow angles in systole ( P = .007) compared with those who underwent biventricular operations. Three patients undergoing biventricular operations underwent transplantation or died and had lower indexed LV end-diastolic volumes compared with the remaining patients ( P = .005). Interobserver agreement for the measured echocardiographic indices was good (intraclass correlation coefficient = 0.70–0.95). Ventricular septal defect size and RV/LV inflow angle in systole had a strong negative correlation (r = −0.7, P < .001). In the validation cohort ( n = 12), RV/LV inflow angle in systole ≤ 114° yielded sensitivity of 100% and AVVI ≤ 0.70 yielded sensitivity of 88% for single-ventricle palliation.
Conclusions
Mortality remains high among patients with right-dominant AVSD. RV/LV inflow angle in systole and AVVI are reproducible measurements that may be used in conjunction with several echocardiographic parameters to support suitability for a biventricular operation in right-dominant AVSD.
Management of moderate forms of unbalanced atrioventricular septal defect (AVSD) remains a challenge given the spectrum of ventricular hypoplasia. The degree of unbalance ultimately affects surgical repair strategy, which may involve a biventricular operation, single-ventricle palliation, or transplantation. Given the broad spectrum of presentation and varying surgical decisions, overall surgical outcomes of unbalanced AVSD remain poor, illustrating the need to better categorize patients preoperatively as suitable for a biventricular operation.
Transthoracic echocardiography remains an essential diagnostic tool in the evaluation of patients with unbalanced AVSD, as it provides critical information regarding the morphology of the atrioventricular valve, presence of valvar stenosis and/or regurgitation, ventricular size, and associated structural abnormalities such as left ventricular (LV) outflow tract obstruction. However, definitive echocardiographic criteria to define the degree of unbalance to guide operative strategy have not been established. Prior studies have examined novel echocardiographic indices, including atrioventricular valve index (AVVI) and right ventricular (RV)/LV inflow angle (RV/LV inflow angle) to delineate the degree of atrioventricular valve and ventricular size discrepancy, which have been proposed to be useful in surgical decision making in this patient population. The goals of this study were to evaluate previously described indices and additional echocardiographic measurements to assess the morphology and physiology of right-dominant AVSD and to investigate factors associated with operative strategy at our institution.
Methods
Patient Population
The Lucile Packard Children’s Hospital (Stanford Children’s Health) Heart Center database was queried retrospectively to identify all eligible patients diagnosed with complete AVSD between January 2000 and July 2013.
Patients were defined as having unbalanced or balanced AVSD by the attending echocardiographer at the time of the initial clinical evaluation on the basis of a comprehensive echocardiographic assessment of atrioventricular valve sizes, ventricular volumes, papillary muscle architecture, and apex formation. Patients initially described as unbalanced were then confirmed by the primary observer to be unbalanced, with the ratio of the smaller atrioventricular valve area divided by the larger atrioventricular valve area as <0.8 to ensure that mild forms of unbalanced AVSD were included.
Criteria for inclusion were thus (1) unbalanced right-dominant AVSD on initial clinical evaluation and (2) adequate echocardiographic imaging quality for analysis on the preoperative transthoracic echocardiogram. Patients with (1) other forms of AVSD, including balanced, left-dominant, transitional, or partial, (2) atrioventricular or aortic valve atresia, (3) confirmed genetic abnormalities with the exception of trisomy 21, and (4) age > 1 year at the time of surgery were excluded from this study. Patients with transitional and partial AVSD were specifically excluded because they typically represent a balanced form of AVSD.
Data on surgical strategy for each patient were not collected until all echocardiographic measurements were obtained. None of the patients included in this study were clinically managed by the primary observer. A subsequent cohort of patients from August 2013 to July 2016 who met inclusion criteria was used to retrospectively evaluate the validity of the initial variable cutoffs. This validation cohort remained unbiased because the echocardiographic parameters assessed in this study were not yet used in formal clinical practice to influence surgical outcomes at our institution.
Each patient’s diagnosis, gender, date of birth, height, weight, body surface area (Haycock formula), date of surgical procedure, type of surgical procedure, and date of preoperative echocardiography were obtained from electronic medical records.
Echocardiographic Data
Transthoracic echocardiographic studies were performed in all patients as part of their routine pre- and postoperative evaluations. Images were acquired according to American Society of Echocardiography guidelines and stored in our institution’s secure server. The ultrasound equipment used for the echocardiographic studies was either the Siemens Sequoia C512 (Siemens Medical Solutions USA, Mountain View, CA) or the Philips iE33 (Philips Medical Systems, Bothell, WA).
For each patient, the preoperative echocardiogram was selected for analysis. An investigator blinded to the type of surgical procedure made offline measurements using the Syngo Dynamics workstation (Siemens Medical Solutions USA; Syngo Dynamics Solutions, Ann Arbor, MI).
Echocardiographic measurements included LV end-diastolic and end-systolic dimensions (parasternal short-axis view), LV and RV widths and lengths (apical four-chamber view) in diastole and systole, LV end-diastolic and end-systolic volumes (5/6 × area × length formula), and RV end-diastolic and end-systolic volumes. LV and RV systolic function was assessed using the 5/6 × area × length and fractional area change, respectively. Aortic arch and semilunar valve annular dimensions were measured, and Z scores were calculated when applicable. Atrioventricular valve regurgitation was graded as mild, moderate, or severe on the basis of defined criteria by the American Society of Echocardiography’s Nomenclature and Standards Committee and the Task Force on Valvular Regurgitation. The direction of flow in the transverse aortic arch, as well as morphologic abnormalities of the left atrioventricular valve (papillary muscle and chordae architecture), were recorded.
AVVI was measured as the ratio of the left atrioventricular valve area divided by the right atrioventricular valve area, as defined in prior studies. LV inflow index was measured as the ratio of the left atrioventricular valve diameter divided by the diameter of color Doppler flow into the left ventricle at the level of the papillary muscles. RV/LV inflow angle was measured in the apical four-chamber view as the angle through the right and left lateral atrioventricular valve hinge points using the crest of the interventricular septum as the crux of the angle, measured in systole and diastole ( Figure 1 ). The size of the ventricular septal defect was also measured from the atrioventricular valve plane to the crest of the ventricular septum in systole in the apical four-chamber view.
A second blinded investigator performed measurements of LV end-diastolic volume (LVEDV), AVVI, and RV/LV inflow angle by the same methodology on a subset of 10 patients selected using random number generation in a Microsoft Excel spreadsheet (Microsoft, Redmond, WA) to determine interobserver variability and reproducibility.
Statistical Analysis
The analysis was performed in an original cohort and a subsequent validation cohort. Descriptive statistics were calculated, with continuous data presented as mean ± SD, median (range), and 95% CIs. The patients were divided into two groups: (1) single-ventricle palliation and (2) biventricular operation. Among the patients who underwent biventricular operations, comparisons were made between survivors and those patients who required heart transplantation or did not survive. Parametric testing was used to compare data with normal distributions. Nonparametric testing was used to compare data with non-normal distributions. All unpaired comparisons were performed using Student’s t test or the Mann-Whitney U test. The Fisher exact test was used to compare type of surgical repair when stratified by degree of atrioventricular valve regurgitation, as well as adverse outcomes (death, transplantation) between two surgical eras (2000–2006 and 2007–2013). Pearson correlation analysis was performed to examine the relationship between ventricular septal defect size (indexed to body surface area) and RV/LV inflow angle in systole.
Receiver operating characteristic curves were generated to determine variable cutoffs and potential indices associated with single-ventricle palliation. A log-rank test was run to determine if there was a difference in survival distribution between the two operative groups (Kaplan-Meier method).
Further subanalyses were performed in the original cohort by (1) excluding patients with trisomy 21, (2) excluding patients with total anomalous pulmonary venous connection, and (3) excluding both patient populations. Intraclass correlation analysis was used to compare LVEDV, AVVI, and RV/LV inflow angle measurements between two lead investigators. A two-sided P value of <.05 was considered to indicate statistical significance. All analyses were performed using IBM SPSS Statistics version 22.0 (IBM, Armonk, NY). The study protocol was approved by the Stanford University institutional review board (protocol 27461).
Results
Patient Population
Between January 2000 and July 2013, 181 patients with AVSD underwent surgery at our institution. Of those, 133 patients had balanced complete AVSD, left-dominant AVSD, transitional AVSD, or partial AVSD. Two patients had right-dominant AVSD but underwent surgery at >1 year of age and were excluded from our study to maintain age homogeneity in the cohort and prevent outcome bias. Forty-six patients with unbalanced right-dominant AVSD were ultimately included in our analysis.
The median age at the time of echocardiography was 1 day (range, 2 hours to 11 months). There was a male predominance. Eleven patients (24%) had trisomy 21, and 20 patients (43%) had heterotaxy syndrome with right atrial isomerism ( Tables 1 and 2 ). Twenty-eight patients (61%) underwent single-ventricle palliation, and the remaining 18 patients (39%) underwent biventricular operations. The average time between preoperative echocardiography and surgery was 14 ± 31 days.
| Characteristic | Patients ( n = 46) |
|---|---|
| Age | 1 day (2 hours to 11 months) |
| Male | 31 (67%) |
| Body surface area (m 2 ) | 0.23 ± 0.04 |
| Trisomy 21 ∗ | 11 (23%) |
| Heterotaxy syndrome | 20 (43%) |
| Single-ventricle palliation | 28 (61%) |
| Transplantation | 1 |
| Death | 9 |
| Biventricular operation | 18 (39%) |
| Transplantation | 1 |
| Death | 2 |
∗ Two patients with trisomy 21 underwent single-ventricle palliation, and nine patients with trisomy 21 underwent biventricular operations.
| Patient | Heterotaxy | Associated CHD | Primary surgical procedure | Secondary surgical procedure | Heart transplantation or death |
|---|---|---|---|---|---|
| 1 | Yes, RAI | D-TGA, pulmonary atresia, MAPCAs, TAPVC | Bilateral unifocalization to central shunt, TAPVC repair, atrial septectomy | Rastelli-type VSD closure, RV-PA conduit, takedown of central shunt | No |
| 2 | Yes, RAI | Pulmonary atresia, TAPVC | Central shunt (intent to single ventricle), TAPVC repair | NA | Transplantation |
| 3 | No | Hypoplastic aortic arch | Single-patch ASD/VSD closure, aortic arch repair | NA | No |
| 4 | No | Midmuscular VSD, PDA | PA band, PDA ligation | Bidirectional Glenn | No |
| 5 | No | Secundum ASD, hypoplastic aortic valve | Single-patch ASD/VSD closure | NA | No |
| 6 | Yes, RAI | DORV, D-TGA, TAPVC, PDA | PA band, PDA ligation, TAPVC repair (intent to single ventricle) | NA | Death |
| 7 | No | LSVC | Two-patch ASD/VSD closure | NA | No |
| 8 | No | DORV, pulmonary stenosis, secundum ASD, PAPVC | Central shunt | Bidirectional Glenn, PAPVC repair | No |
| 9 | No | None | Two-patch ASD/VSD closure | NA | No |
| 10 | Yes, RAI | Pulmonary atresia, MAPCAs, TAPVC, LSVC, PDA | Bilateral unifocalization to BT shunt, TAPVC repair, PDA ligation | Bilateral bidirectional Glenn | No |
| 11 | No | Pulmonary stenosis | Single-patch ASD/VSD closure, RVOT resection and pulmonary valve commissurotomy | NA | No |
| 12 | No | PDA | Single-patch ASD/VSD closure, PDA ligation | NA | No |
| 13 | Yes, RAI | Aortic coarctation | Norwood/Sano procedure | Bidirectional Glenn | No |
| 14 | Yes, RAI | D-TGA, pulmonary atresia, TAPVC, PDA | BT shunt, TAPVC repair, PDA ligation (intent to single ventricle) | NA | Death |
| 15 | No | Bicuspid aortic valve, aortic coarctation | Norwood/Sano procedure | NA | Death |
| 16 | No | Hypoplastic aortic arch | Single-patch ASD/VSD closure, aortic arch repair | NA | No |
| 17 | No | PDA | PA band, PDA ligation | Bidirectional Glenn, left atrioventricular valve closure | No |
| 18 | No | Aortic coarctation, LSVC | Two-patch ASD/VSD closure, aortic arch repair | NA | No |
| 19 | Yes, RAI | D-TGA, pulmonary atresia, TAPVC, LSVC, PDA | Central shunt, TAPVC repair, PDA ligation | Bidirectional Glenn | Death |
| 20 | No | None | PA band | Bidirectional Glenn | No |
| 21 | No | Secundum ASD, PDA | Single-patch ASD/VSD closure, PDA ligation | NA | No |
| 22 | Yes, RAI | DORV, TAPVC, LSVC, PDA | PA band, TAPVC repair, PDA ligation | BT shunt; subsequent bilateral bidirectional Glenn | Death |
| 23 | No | Aortic coarctation, TAPVC, LSVC, PDA | Norwood/BT shunt procedure, TAPVC repair, PDA ligation | NA | Death |
| 24 | Yes, RAI | DORV, D-TGA, pulmonary stenosis, TAPVC, LSVC, PDA | TAPVC repair, PDA ligation | Bilateral bidirectional Glenn | No |
| 25 | Yes, RAI | DORV, TAPVC, LSVC | PAB, TAPVC repair | Bilateral bidirectional Glenn | No |
| 26 | No | None | Two-patch ASD/VSD closure | Left atrioventricular valve repair | Death |
| 27 | Yes, RAI | DORV, D-TGA, pulmonary stenosis, TAPVC | BT shunt, TAPVC repair (intent to single ventricle) | NA | Death |
| 28 | No | D-TGA, pulmonary atresia, LSVC | BT shunt | Bilateral bidirectional Glenn | No |
| 29 | Yes, RAI | DORV, pulmonary atresia, TAPVC | Central shunt, TAPVC repair | Bidirectional Glenn | No |
| 30 | No | Aortic coarctation | Two-patch ASD/VSD closure, aortic arch repair | NA | Death |
| 31 | Yes, RAI | D-TGA, pulmonary stenosis, TAPVC, LSVC | TAPVC repair | Bilateral bidirectional Glenn | No |
| 32 | No | D-TGA, pulmonary atresia, cor triatriatum | BT shunt | Bidirectional Glenn | No |
| 33 | No | D-TGA, pulmonary atresia, MAPCAs, TAPVC | Bilateral unifocalization to central shunt, TAPVC repair (intent to single ventricle) | NA | Death |
| 34 | Yes, RAI | DORV, D-TGA, pulmonary stenosis | BT shunt | Bidirectional Glenn | No |
| 35 | No | PDA | Single-patch ASD/VSD closure, PDA ligation | NA | No |
| 36 | Yes, RAI | DORV, D-TGA, pulmonary stenosis, TAPVC, LSVC | BT shunt, TAPVC repair | Bilateral bidirectional Glenn | No |
| 37 | No | Pulmonary stenosis, aortic coarctation | Hybrid stage I | NA | Death |
| 38 | No | Aortic coarctation | Norwood/Sano procedure | Bidirectional Glenn | No |
| 39 | Yes, RAI | DORV, D-TGA, pulmonary atresia, TAPVC | Central shunt, TAPVC repair | Rastelli-type VSD closure, RV-PA conduit | No |
| 40 | No | Aortic coarctation | Single-patch ASD/VSD closure, aortic arch repair | NA | No |
| 41 | Yes, RAI | Hypoplastic aortic arch | Two-patch ASD/VSD closure, aortic arch repair | Left atrioventricular valve replacement | Transplantation |
| 42 | No | Secundum ASD | Single-patch ASD/VSD closure | NA | No |
| 43 | Yes, RAI | DORV, aortic stenosis, aortic coarctation | Norwood/Sano procedure | Bidirectional Glenn | No |
| 44 | No | DORV, D-TGA, pulmonary stenosis | BT shunt | Bidirectional Glenn | No |
| 45 | Yes, RAI | DORV, D-TGA, pulmonary atresia | Central shunt | Bidirectional Glenn | No |
| 46 | Yes, RAI | DORV, D-TGA, TAPVC | PA band, TAPVC repair | Arterial switch, VSD closure; subsequent left atrioventricular valve repair | No |
More patients with trisomy 21 underwent biventricular operations compared with single-ventricle palliation (50% vs 7%, P = .0015). In the single-ventricle palliation group, there was a higher percentage of patients with total anomalous pulmonary venous connection (48% vs 16%, P = .03).
The operations for each patient are listed in Table 2 . Of the 18 patients who underwent single-ventricle palliation, six (33%) required a Norwood procedure before bidirectional Glenn. Nine patients (50%) had D-looped transposition of the great arteries or Taussig-Bing-type double-outlet right ventricle with pulmonary valve stenosis or atresia requiring a Blalock-Taussig or central shunt. Five patients (28%) proceeding down the single-ventricle pathway died during the interstage period after attempted surgical management of pulmonary blood flow (shunt or pulmonary artery band).
Three patients who ultimately underwent biventricular operations began with primary surgical procedures to regulate pulmonary blood flow (shunt or pulmonary artery band) and repair of total anomalous pulmonary venous connection before definitive surgery ( Table 2 ).
Echocardiographic Indices
Biventricular Operation versus Single-Ventricle Palliation
Echocardiographic parameters for the groups that underwent biventricular operation and single-ventricle palliation are presented in Table 3 . Overall, echocardiographic measurements of LV size were smaller in the single-ventricle palliation group compared with the biventricular operation group. Of the specific echocardiographic indices used to assess patients with right-dominant AVSD, AVVI and RV/LV inflow angle in systole were found to be significantly smaller in the single-ventricle palliation group ( P = .005 and P = .007, respectively).
| Echocardiographic measurement | n | Single-ventricle palliation | Biventricular operation | P |
|---|---|---|---|---|
| LVEDD, Z score | 46 | −4.95 ± 3.28 | −4.22 ± 1.53 | .03 |
| LVESD, Z score | 46 | −4.07 ± 3.58 | −4.00 ± 1.45 | .106 |
| FS (%) | 46 | 36.6 ± 10.7 | 41.2 ± 11.2 | .19 |
| FS, Z score | 46 | −0.28 ± 3.46 | 1.21 ± 3.33 | .13 |
| LV end-diastolic area, 4C view (cm 2 ) | 46 | 1.71 ± 1.38 | 2.40 ± 0.93 | .004 |
| LV end-systolic area, 4C view (cm 2 ) | 46 | 1.01 ± 0.79 | 1.28 ± 0.45 | .008 |
| RV end-diastolic area, 4C view (cm 2 ) | 46 | 2.68 ± 0.81 | 3.60 ± 1.41 | .02 |
| RV end-systolic area, 4C view (cm 2 ) | 46 | 1.68 ± 0.57 | 2.29 ± 1.15 | .07 |
| LV width, diastole (cm) | 46 | 0.87 ± 0.44 | 1.07 ± 0.29 | .007 |
| LV width, systole (cm) | 46 | 0.63 ± 0.36 | 0.68 ± 0.24 | .17 |
| LV end-diastolic area, SAX view (cm 2 ) | 40 | 1.65 ± 2.10 | 2.43 ± 1.13 | <.001 |
| LV end-systolic area, SAX view (cm 2 ) | 40 | 0.74 ± 1.00 | 0.97 ± 0.56 | .003 |
| LV end-diastolic length, 4C view (cm) | 46 | 1.97 ± 0.47 | 2.40 ± 0.55 | .009 |
| LV end-systolic length, 4C view (cm) | 46 | 1.58 ± 0.42 | 1.91 ± 0.33 | .006 |
| LVEDV (mL) | 40 | 2.99 ± 5.23 | 5.13 ± 3.29 | <.001 |
| Indexed LVEDV (mL/m 2 ) | 40 | 14.03 ± 21.69 | 20.93 ± 12.65 | <.001 |
| LVEDV Z score | 40 | −1.83 ± 3.41 | −0.78 ± 2.14 | .004 |
| LVESV (mL) | 40 | 1.06 ± 1.87 | 1.56 ± 1.03 | .001 |
| Indexed LVESV (mL/m 2 ) | 40 | 4.72 ± 7.59 | 6.47 ± 4.07 | .004 |
| LVESV Z score | 40 | −6.62 ± 3.80 | −4.09 ± 2.42 | .008 |
| LVEF (%) | 40 | 65.2 ± 13.8 | 68.1 ± 8.8 | .60 |
| RVEDV (mL) | 42 | 3.15 ± 3.38 | 6.39 ± 5.34 | .04 |
| RVESV (mL) | 42 | 1.59 ± 1.83 | 3.43 ± 3.53 | .08 |
| RV FAC (%) | 42 | 47.8 ± 15.2 | 50.0 ± 12.0 | .96 |
| LVEDV/RVEDV ratio | 40 | 0.49 ± 0.27 | 0.65 ± 0.34 | .16 |
| LVESV/RVESV ratio | 40 | 0.37 ± 0.26 | 0.47 ± 0.28 | .35 |
| Ventricular cavity ratio ([LV width × LV length]/[RV width × RV length]) | 46 | 0.77 ± 1.24 | 0.68 ± 0.36 | .74 |
| Aortic valve annulus, Z score | 44 | 0.07 ± 2.34 | −0.86 ± 2.53 | .22 |
| Aortic arch, ascending, Z score | 45 | −0.62 ± 1.23 | −0.87 ± 1.60 | .56 |
| Aortic arch, distal transverse, Z score | 44 | −0.76 ± 1.80 | −1.57 ± 1.95 | .16 |
| Aortic arch, isthmus, Z score | 42 | −0.80 ± 1.08 | −1.26 ± 1.17 | .19 |
| Pulmonary valve annulus, Z score | 31 | −1.66 ± 1.06 | −0.55 ± 0.82 | .004 |
| AVVI | 42 | 0.57 ± 0.16 | 0.72 ± 0.14 | .005 |
| LV inflow index | 18 | 0.88 ± 0.17 | 0.83 ± 0.26 | .63 |
| RV/LV inflow angle, diastole (deg) | 46 | 90.1 ± 19.9 | 100.7 ± 20.7 | .09 |
| RV/LV inflow angle, systole (deg) | 46 | 107.8 ± 22.3 | 126.2 ± 20.3 | .007 |
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