ORIGINAL ARTICLE – CONGENITAL
Interactive CardioVascular and Thoracic Surgery 18 (2014) 789–796 doi:10.1093/icvts/ivu026 Advance Access publication 28 February 2014
Experience with the surgical treatment of atrioventricular septal defect with left ventricular outflow tract obstruction† Tomas Tlaskal*, Roman Gebauer, Jiri Gilik and Viktor Tomek Children’s Heart Centre, University Hospital Motol, Prague, Czech Republic
Received 24 September 2013; received in revised form 12 January 2014; accepted 20 January 2014
Abstract OBJECTIVES: We sought to determine the prevalence, morphology, surgical methods and results of surgery for left ventricular outflow tract obstruction (LVOTO) associated with atrioventricular septal defect (AVSD). METHODS: Correction of AVSD was performed in 615 patients. Twenty-three (3.7%) patients with LVOTO were identified. Sixteen (70%) of them had partial and 7 (30%) had complete AVSD. Surgery for AVSD was performed at a median of 0.6 years (mean 2.1 ± 3.0 years), and surgery for LVOTO at a median of 3.4 years (mean 4.7 ± 3.5 years). The point and period prevalence of LVOTO in AVSD were determined. Detailed morphological study, individualized repair of AVSD with LVOTO and long-term follow-up were performed. Early and long-term results were analysed. RESULTS: The point prevalence of LVOTO at the time of AVSD repair was 1.3%. The period prevalence of LVOTO was 3.7% in course of 8.3 ± 6.0 (0–18.4) years and 191.4 patient-years following AVSD repair. Causes of LVOTO were fibromuscular membrane (n = 17), septal hypertrophy (n = 17), abnormal atrioventricular (AV) valve (n = 9), muscular bands (n = 3), fibrous strands (n = 4) and stenotic aortic valve (n = 2). Usually, a combination of several obstructive lesions was present. LVOTO was present at the time of AVSD repair in 8 patients (35%) and developed after repair in 15 (65%) patients. Membrane excision (n = 17), myectomy (n = 17), excision of abnormal AV valvar tissue (n = 8), excision of muscular bands and fibrous strands (n = 6), AV valve replacement (n = 2) and aortic valvotomy (n = 2) were required. There was 1 (4%) early and 1 (4%) late death. Six (29%) survivors required reoperation for recurrence of LVOTO at an average interval of 6.3 ± 3.2 years after surgery. The actuarial survival at 1 and 10 years was 96 and 88%, respectively. The actuarial freedom from reoperation for LVOTO was 80, 40 and 20% at 6, 10 and 15 years after surgery, respectively. Eighteen (78%) patients remain in good condition at mean 6.0 ± 5.5 years after surgery. CONCLUSIONS: The point prevalence of LVOTO at the time of AVSD repair was 1.3%, and period prevalence 3.7%. Fibromuscular membrane, septal hypertrophy and valvar attachments represent the most common causes of LVOTO. Usually, more structures are involved. The repair must be individualized. The presence of LVOTO increases the need for reoperation. Keywords: Congenital heart disease • Atrioventricular septal defect • Left ventricular outflow tract obstruction • Surgical treatment • Reoperations • Long-term results
INTRODUCTION Atrioventricular septal defect (AVSD) is characterized by septal defect in the atrioventricular (AV) septum and adjacent atrial and ventricular septum, prolongation and narrowing of the left ventricular outflow tract (LVOT), scooped out appearance of the superior margin of the septum, and malformation of AV valves with a common AV junction [1–3]. Correction of AVSD was first performed by Lillehei et al. [4] in 1955, followed by many others, but the surgery was associated with high mortality [3]. Growing experience lead to considerable improvement of early and long-term results. Today the repair of AVSD can be performed with early mortality 50 mmHg across LVOT, echocardiography and/or perioperative findings of LVOTO or anomalous structures in the LVOT with an increased risk of LVOTO development after the repair. Before surgery for AVSD, 4 patients underwent 6 palliative procedures. The baseline characteristics of the series are summarized in Table 1.
Morphology and terminology The morphology of AVSD and LVOT was studied pre- and intraoperatively by complex echocardiography study and by visual examination. All structures causing unequivocal or potential LVOTO were identified. AVSD with a common AV orifice and a large interventricular communication was described as complete AVSD, and AVSD with two orifices and/or restrictive interventricular communication was described as partial AVSD. The Rastelli classification was used for description of individual types of complete AVSD [15]. Four (57%) of the 7 patients with complete AVSD had Type A and 3 (43%) patients had Type C. Regurgitation of the left or the common AV valve was present in 20 (87%) patients. It was minimal in 8 patients (34%), mild in 7 (29%), moderate in 2 (8%) and severe in 3 (12%) patients. In 2 (8%) patients, severe right AV valve regurgitation was detected. Associated heart lesions were found in 16 (70%) patients: atrial septal defect or patent foramen ovale in 9 (39%), coarctation of the aorta in 4 (17%), patent ductus arteriosus in 4 (17%), pulmonary stenosis in 3 (12%), bicuspid aortic valve in 2 (8%) and mitral stenosis, quadricuspid aortic valve and left superior caval vein in 1 (4%) patient each.
Surgical methods The surgery was performed in mild or moderate hypothermia, and for myocardial protection, cold St Thomas Hospital crystalloid cardioplegia was used. The correction consisted in patch closure of the partial AVSD and in two-patch repair of the complete AVSD. Individually modified plasty of both AV valves was performed. The plasty of AV valves was based on complex preoperative echocardiography detailed perioperative examination and testing of AV valve competence by injection of cold saline solution into the left ventricle. Routinely, the zone of apposition (‘cleft’) was completely closed with individual stitches. LVOTO was approached through a standard oblique aortotomy or a right atriotomy. The valvar AS was repaired by valvotomy and ‘shaving’ of thick valve cusps. Excision of fibromuscular membrane and anomalous fibrous tissue from LVOT was performed. At the same time, myectomy was always performed to enlarge the LVOT adequately in all parts. Excision of accessory AV valvar tissue was required. Associated heart lesions were repaired. Survivors were followed and examined by echocardiography in the outpatient department of our institution.
RESULTS Morphology The occurrence of LVOTO in the total cohort of 615 patients was 3.7%. The point prevalence of LVOTO at the time of AVSD repair was 1.3% (8 patients) in 615 patients. It was 0.8% (2 of 252 patients) in the complete AVSD and 1.7% (6 of 363 patients) in the partial
T. Tlaskal et al. / Interactive CardioVascular and Thoracic Surgery
791
Characteristics
Partial AVSD (n = 16), n (%)
Complete AVSD (n = 7), n (%)
P-value
Unfavourable anatomy of AV valves Dysplastic AV valve Single papillary muscle Double-orifice valve Anteriorly oriented ‘cleft’ Wide ‘cleft’ Papillary muscle close to each other LVOTO—fibromuscular membrane LVOTO—muscular hypertrophy LVOTO—fibrous strands and chordae LVOTO—anomalous AV valve and papillary muscle Accessory AV valvar tissue Attachments of AV valve Hypertrophic papillary muscle LVOTO—hypertrophic muscle bands Valvar aortic stenosis
14 (88) 9 (56) 2 (13) 2 (13) 4 (25) 3 (19) 1 (6) 13 (81) 13 (81) 4 (25) 5 (31) 2 (13) 2 (13) 1 (6) 3 (19) 1 (6)
4 (57) 2 (29) 1 (14) 0 0 0 0 4 (57) 4 (57) 0 4 (57) 3 (43) 0 1 (14) 0 1 (14)
0.41 0.38 0.69 0.58 0.28 0.37 0.71 0.45 0.45 0.28 0.36 0.23 0.51 0.55 0.37 0.55
AV: atrioventricular; AVSD: atrioventricular septal defect; LVOTO: left ventricular outflow tract obstruction.
AVSD (P = 0.58). The period prevalence of LVOTO following AVSD repair was 3.7% in the course of the follow-up time of 8.3 ± 6.0 (0– 18.4) years and 191.4 patient-years. The period prevalence was similar for complete and partial AVSD (2.8 vs 3.9%, P = 0.64). The morphological characteristics of the 23 patients are reported in Table 2. Two patients with a partial AVSD had restrictive interventricular communication. They could be classified also as a transitional or intermediate form. LVOTO was subvalvar in 21 (92%) patients; in 1 (4%) patient a combination of LVOTO and valvar AS was found, and in 1 (4%) patient, only valvar AS was found. Subvalvar LVOTO was usually complex and several different obstructive structures were involved. Most commonly, a thick circular or semilunar fibromuscular membrane localized at different levels of LVOT caused obstruction. The membrane represented the most important obstructive structure in 16 (70%) patients. It was always associated with a localized muscular hypertrophy of the septum and the LV-free wall. The muscular hypertrophy was considered the most important obstructive structure in 3 (12%) patients and the anomalous AV valve in 1 (4%) patient. Anomalies of AV valvar tissue, papillary muscles, attachments or chordae participated in complex substrate of LVOTO in 9 (39%) patients. In 18 (78%) patients, unfavourable and potentially obstructive morphology of the left or the common AV valve was present. The left or the common valve had potentially stenotic morphology in 10 (44%) patients, and in 1 (4%) patient, unequivocal ‘mitral’ stenosis was found. The most common was a condition in which the AV valve was abnormally thick or dysplastic. In 2 (8%) patients, LVOTO was tubular.
Surgery In 11 (48%) patients the ‘cleft’ was closed completely, in 6 (26%) patients with potentially stenotic morphology of the left AV valve the ‘cleft’ was sutured incompletely, and in 4 (17%) patients the ‘cleft’ could not be sutured at all. In 7 (30%) patients, commissuroplasty or plasty with a pericardial patch was used. In Table 3,
Table 3: Surgical procedures for relief of left ventricular outflow tract obstruction Procedure
All procedures for LVOTO n (%)
Resection of fibromuscular membrane Myectomy Excision of anomalous AV valvar tissue Excision of muscle bundles Excision of fibrous strands Replacement of left AV valve Aortic valvotomy Partial resection of anterior papillary muscle
17 (74) 17 (74) 9 (39) 3 (13) 3 (13) 2 (9) 2 (9) 1 (4)
AV: atrioventricular; LVOTO: left ventricular outflow tract obstruction. In most patients, the surgery for relief of LVOTO was complex and required intervention on several different structures.
methods used for correction of LVOTO are summarized, and in Fig. 1, schema of individual procedures are demonstrated. Excision of the membrane represented the most important procedure for relief of LVOTO in 16 (70%) patients and myectomy in 3 (12%) patients. Excision of the left AV valve and valve replacement with a mechanical valve was required in 2 (9%) patients with unfavourable anatomy of AV valves and hypertrophic papillary muscles, which obstructed the path between the inflow and the outflow part of the left ventricle and caused LVOTO. In 1 (4%) patient who had very long and hypertrophic anterolateral papillary muscle, it was necessary to mobilize attachments of the papillary muscle to the septum and free wall, and to thin the obstructive myocardial mass by partial resection of this papillary muscle. In 3 (12%) patients, pulmonary valvotomy was performed, and in one of them, enlargement of the right ventricular outflow tract with a monocusp transannular patch was required.
ORIGINAL ARTICLE
Table 2: Morphology
792
T. Tlaskal et al. / Interactive CardioVascular and Thoracic Surgery
Figure 1: Methods of the left ventricular outflow tract repair in patients with atrioventricular septal defect. (a) Excision of a fibromuscular membrane and radical myectomy. (b) Mobilization and partial resection of a hypertrophic anterior papillary muscle obstructing the left ventricular outflow tract. (c) Excision of the left atrioventricular valve. Hypertrophic anterior papillary muscle caused severe left ventricular outflow tract obstruction, which could not be released. The left atrioventricular valve was replaced with a mechanical valve.
Postoperative mortality Table 4: One (4%) patient died early and 1 (4%) patient died late from heart failure, both deaths occurred before 1995. Both patients who died had partial AVSD with very unfavourable morphology of the left AV valve. The first child also had valvar pulmonary stenosis, small pulmonary annulus and anomalous attachments of the left AV valve in LVOT. This complex anatomy was associated with severe biventricular hypertrophy. At repair, the right ventricular obstruction was released by transannular patch with a monocusp pericardial valve. The subaortic obstruction caused by anomalous attachments of the left AV valve could not be released. The child died 6 days after surgery. The late mortality occurred in a 6-year old girl with a stenotic left AV valve. The hypertrophic papillary muscles caused low-laying localized LVOTO. The repair required the left AV valve replacement. This procedure improved LV inflow and released the LVOTO. The girl suffered, however, from arrhythmias and left heart failure, which led to her death 3 years after the repair. Insignificant difference in mortality between partial and complete AVSD was found (2 of 16 patients or 13% in partial vs 0 of 7 patients or 0% in complete AVSD, P = 0.51).
Follow-up After repair of AVSD with LVOTO in 23 patients, the clinical condition of 21 (91%) children improved. During the follow-up, however,
Reoperations
Procedure
n
Resection of fibromuscular membrane Left AV valve replacement Plasty of left AV valve Pacemaker implantation Excision of anomalous valvar tissue Residual VSD closure Residual ASD closure Resection of coarctation of the aorta
5 3 2 2 1 1 1 1
ASD: atrial septal defect; AV: atrioventricular; VSD: ventricular septal defect.
recurrence and progression of LVOTO was observed in 9 (41%) patients, and in 6 of them, reoperation was necessary (Table 4). The average gradient across LVOT before reoperation was 76 ± 10 mmHg (range 65–90). The reoperation for subvalvar AS was performed at a median age of 9.7 years (mean 10.1 ± 3.3 years, range 5.8–15.5 years), and a median of 6.5 years (6.3 ± 3.2 years, range 2.7–12.2 years) after surgery for LVOTO. In 5 reoperated children, the surgery consisted in excision of fibromuscular membrane and myectomy. In 1 patient, excision of anomalous left AV valve attachments was also required. In another reoperated child, it was
necessary to excise the left AV valve together with papillary muscles that caused the subaortic obstruction. In 2 reoperated patients, plasty of the left AV valve was also required. Six other reoperations were required in 4 patients. Table 4 summarizes all 16 surgical procedures performed as reoperations in 10 patients. Today, 21 (91%) patients remain in New York Heart Association functional Class I or II, median 5.2 years (mean 6.0 ± 5.5 years, range 0–18.4 years) after surgery. The actuarial survival (expressed by the Kaplan–Meier estimate) in patients with AVSD and LVOTO was 96, 88 and 88%, respectively, at 1, 10 and 15 years after surgery for LVOTO. The survival without reoperation for LVOTO is median 3.0 years (mean 4.4 ± 4.3 years, range 0–17.7 years). In the group of 22 early survivors the actuarial freedom from reoperation for LVOTO at 1, 6, 10 and 15 years, respectively, after surgery for LVOTO is 100, 80, 40 and 20%, respectively. However, the systolic pressure gradient across LVOT gradually rose in 3 (14%) other patients and reached 56, 45 and 41 mmHg, respectively. All these 3 patients originally had dysplastic left AV valve.
Limitations of the study The relative rarity and morphological variability of LVOTO in the association with AVSD resulted in small sample sizes of all individual subgroups of patients in this cohort of operated patients. Any meaningful statistical analysis is therefore limited.
DISCUSSION AVSD represents morphologically an extremely variable congenital heart disease. Prolongation and narrowing of LVOT represent typical characteristics of all hearts with AVSD, but in some hearts, potential or unequivocal LVOTO can be detected [2, 3, 7–10]. Preoperatively, real LVOTO with a significant pressure gradient is rare. Morphological changes of all structures forming LVOT may, however, increase the risk of damasking stenosis after the repair [11, 13]. These changes include more extensive deficiency of the outlet septum, hypertrophy of the LV free wall and septum, accessory left AV valvar tissue, hypertrophic and/or more anteriorly and superiorly attached anterolateral or accessory papillary muscle, thick chordae attached more to the left and inside LVOT, hypertrophic anterolateral muscle band, anomalous fibrous strands in LVOT and aortic valvar anomalies [2, 8, 14, 16, 17]. The changes in the left superior bridging leaflet tissue quality and abnormal septal attachments may add significant risk of LVOTO particularly in hearts with separate orifices and in Type A of the complete AVSD. A very important role in formation of LVOTO is probably played by anomalies of AV valves during the natural history or after the repair of AVSD [14, 16]. Dysplastic AV valve, anomalous attachments with dense fibrous tissue, multiple secondary chordae, fibrous strands between the leaflet and the crest of the interventricular septum, closure of a wide, irregular or anteriorly oriented ‘cleft’ may compromise the valve mobility and narrow the space below the aortic valve. The primary LVOTO is often caused by anomalies of the left AV valve and their attachments, which may provoke turbulence, and formation of a fibrous scar tissue. The fibromuscular membrane develops as a secondary structure in a region of increased blood turbulence in an irregular and anatomically narrow LVOT [11, 12]. The true prevalence of LVOTO in AVSD is not clear. In different series of heart specimens, the incidence is higher than in clinical
793
series, where it is usually
Interactive CardioVascular and Thoracic Surgery 18 (2014) 789–796 doi:10.1093/icvts/ivu026 Advance Access publication 28 February 2014
Experience with the surgical treatment of atrioventricular septal defect with left ventricular outflow tract obstruction† Tomas Tlaskal*, Roman Gebauer, Jiri Gilik and Viktor Tomek Children’s Heart Centre, University Hospital Motol, Prague, Czech Republic
Received 24 September 2013; received in revised form 12 January 2014; accepted 20 January 2014
Abstract OBJECTIVES: We sought to determine the prevalence, morphology, surgical methods and results of surgery for left ventricular outflow tract obstruction (LVOTO) associated with atrioventricular septal defect (AVSD). METHODS: Correction of AVSD was performed in 615 patients. Twenty-three (3.7%) patients with LVOTO were identified. Sixteen (70%) of them had partial and 7 (30%) had complete AVSD. Surgery for AVSD was performed at a median of 0.6 years (mean 2.1 ± 3.0 years), and surgery for LVOTO at a median of 3.4 years (mean 4.7 ± 3.5 years). The point and period prevalence of LVOTO in AVSD were determined. Detailed morphological study, individualized repair of AVSD with LVOTO and long-term follow-up were performed. Early and long-term results were analysed. RESULTS: The point prevalence of LVOTO at the time of AVSD repair was 1.3%. The period prevalence of LVOTO was 3.7% in course of 8.3 ± 6.0 (0–18.4) years and 191.4 patient-years following AVSD repair. Causes of LVOTO were fibromuscular membrane (n = 17), septal hypertrophy (n = 17), abnormal atrioventricular (AV) valve (n = 9), muscular bands (n = 3), fibrous strands (n = 4) and stenotic aortic valve (n = 2). Usually, a combination of several obstructive lesions was present. LVOTO was present at the time of AVSD repair in 8 patients (35%) and developed after repair in 15 (65%) patients. Membrane excision (n = 17), myectomy (n = 17), excision of abnormal AV valvar tissue (n = 8), excision of muscular bands and fibrous strands (n = 6), AV valve replacement (n = 2) and aortic valvotomy (n = 2) were required. There was 1 (4%) early and 1 (4%) late death. Six (29%) survivors required reoperation for recurrence of LVOTO at an average interval of 6.3 ± 3.2 years after surgery. The actuarial survival at 1 and 10 years was 96 and 88%, respectively. The actuarial freedom from reoperation for LVOTO was 80, 40 and 20% at 6, 10 and 15 years after surgery, respectively. Eighteen (78%) patients remain in good condition at mean 6.0 ± 5.5 years after surgery. CONCLUSIONS: The point prevalence of LVOTO at the time of AVSD repair was 1.3%, and period prevalence 3.7%. Fibromuscular membrane, septal hypertrophy and valvar attachments represent the most common causes of LVOTO. Usually, more structures are involved. The repair must be individualized. The presence of LVOTO increases the need for reoperation. Keywords: Congenital heart disease • Atrioventricular septal defect • Left ventricular outflow tract obstruction • Surgical treatment • Reoperations • Long-term results
INTRODUCTION Atrioventricular septal defect (AVSD) is characterized by septal defect in the atrioventricular (AV) septum and adjacent atrial and ventricular septum, prolongation and narrowing of the left ventricular outflow tract (LVOT), scooped out appearance of the superior margin of the septum, and malformation of AV valves with a common AV junction [1–3]. Correction of AVSD was first performed by Lillehei et al. [4] in 1955, followed by many others, but the surgery was associated with high mortality [3]. Growing experience lead to considerable improvement of early and long-term results. Today the repair of AVSD can be performed with early mortality 50 mmHg across LVOT, echocardiography and/or perioperative findings of LVOTO or anomalous structures in the LVOT with an increased risk of LVOTO development after the repair. Before surgery for AVSD, 4 patients underwent 6 palliative procedures. The baseline characteristics of the series are summarized in Table 1.
Morphology and terminology The morphology of AVSD and LVOT was studied pre- and intraoperatively by complex echocardiography study and by visual examination. All structures causing unequivocal or potential LVOTO were identified. AVSD with a common AV orifice and a large interventricular communication was described as complete AVSD, and AVSD with two orifices and/or restrictive interventricular communication was described as partial AVSD. The Rastelli classification was used for description of individual types of complete AVSD [15]. Four (57%) of the 7 patients with complete AVSD had Type A and 3 (43%) patients had Type C. Regurgitation of the left or the common AV valve was present in 20 (87%) patients. It was minimal in 8 patients (34%), mild in 7 (29%), moderate in 2 (8%) and severe in 3 (12%) patients. In 2 (8%) patients, severe right AV valve regurgitation was detected. Associated heart lesions were found in 16 (70%) patients: atrial septal defect or patent foramen ovale in 9 (39%), coarctation of the aorta in 4 (17%), patent ductus arteriosus in 4 (17%), pulmonary stenosis in 3 (12%), bicuspid aortic valve in 2 (8%) and mitral stenosis, quadricuspid aortic valve and left superior caval vein in 1 (4%) patient each.
Surgical methods The surgery was performed in mild or moderate hypothermia, and for myocardial protection, cold St Thomas Hospital crystalloid cardioplegia was used. The correction consisted in patch closure of the partial AVSD and in two-patch repair of the complete AVSD. Individually modified plasty of both AV valves was performed. The plasty of AV valves was based on complex preoperative echocardiography detailed perioperative examination and testing of AV valve competence by injection of cold saline solution into the left ventricle. Routinely, the zone of apposition (‘cleft’) was completely closed with individual stitches. LVOTO was approached through a standard oblique aortotomy or a right atriotomy. The valvar AS was repaired by valvotomy and ‘shaving’ of thick valve cusps. Excision of fibromuscular membrane and anomalous fibrous tissue from LVOT was performed. At the same time, myectomy was always performed to enlarge the LVOT adequately in all parts. Excision of accessory AV valvar tissue was required. Associated heart lesions were repaired. Survivors were followed and examined by echocardiography in the outpatient department of our institution.
RESULTS Morphology The occurrence of LVOTO in the total cohort of 615 patients was 3.7%. The point prevalence of LVOTO at the time of AVSD repair was 1.3% (8 patients) in 615 patients. It was 0.8% (2 of 252 patients) in the complete AVSD and 1.7% (6 of 363 patients) in the partial
T. Tlaskal et al. / Interactive CardioVascular and Thoracic Surgery
791
Characteristics
Partial AVSD (n = 16), n (%)
Complete AVSD (n = 7), n (%)
P-value
Unfavourable anatomy of AV valves Dysplastic AV valve Single papillary muscle Double-orifice valve Anteriorly oriented ‘cleft’ Wide ‘cleft’ Papillary muscle close to each other LVOTO—fibromuscular membrane LVOTO—muscular hypertrophy LVOTO—fibrous strands and chordae LVOTO—anomalous AV valve and papillary muscle Accessory AV valvar tissue Attachments of AV valve Hypertrophic papillary muscle LVOTO—hypertrophic muscle bands Valvar aortic stenosis
14 (88) 9 (56) 2 (13) 2 (13) 4 (25) 3 (19) 1 (6) 13 (81) 13 (81) 4 (25) 5 (31) 2 (13) 2 (13) 1 (6) 3 (19) 1 (6)
4 (57) 2 (29) 1 (14) 0 0 0 0 4 (57) 4 (57) 0 4 (57) 3 (43) 0 1 (14) 0 1 (14)
0.41 0.38 0.69 0.58 0.28 0.37 0.71 0.45 0.45 0.28 0.36 0.23 0.51 0.55 0.37 0.55
AV: atrioventricular; AVSD: atrioventricular septal defect; LVOTO: left ventricular outflow tract obstruction.
AVSD (P = 0.58). The period prevalence of LVOTO following AVSD repair was 3.7% in the course of the follow-up time of 8.3 ± 6.0 (0– 18.4) years and 191.4 patient-years. The period prevalence was similar for complete and partial AVSD (2.8 vs 3.9%, P = 0.64). The morphological characteristics of the 23 patients are reported in Table 2. Two patients with a partial AVSD had restrictive interventricular communication. They could be classified also as a transitional or intermediate form. LVOTO was subvalvar in 21 (92%) patients; in 1 (4%) patient a combination of LVOTO and valvar AS was found, and in 1 (4%) patient, only valvar AS was found. Subvalvar LVOTO was usually complex and several different obstructive structures were involved. Most commonly, a thick circular or semilunar fibromuscular membrane localized at different levels of LVOT caused obstruction. The membrane represented the most important obstructive structure in 16 (70%) patients. It was always associated with a localized muscular hypertrophy of the septum and the LV-free wall. The muscular hypertrophy was considered the most important obstructive structure in 3 (12%) patients and the anomalous AV valve in 1 (4%) patient. Anomalies of AV valvar tissue, papillary muscles, attachments or chordae participated in complex substrate of LVOTO in 9 (39%) patients. In 18 (78%) patients, unfavourable and potentially obstructive morphology of the left or the common AV valve was present. The left or the common valve had potentially stenotic morphology in 10 (44%) patients, and in 1 (4%) patient, unequivocal ‘mitral’ stenosis was found. The most common was a condition in which the AV valve was abnormally thick or dysplastic. In 2 (8%) patients, LVOTO was tubular.
Surgery In 11 (48%) patients the ‘cleft’ was closed completely, in 6 (26%) patients with potentially stenotic morphology of the left AV valve the ‘cleft’ was sutured incompletely, and in 4 (17%) patients the ‘cleft’ could not be sutured at all. In 7 (30%) patients, commissuroplasty or plasty with a pericardial patch was used. In Table 3,
Table 3: Surgical procedures for relief of left ventricular outflow tract obstruction Procedure
All procedures for LVOTO n (%)
Resection of fibromuscular membrane Myectomy Excision of anomalous AV valvar tissue Excision of muscle bundles Excision of fibrous strands Replacement of left AV valve Aortic valvotomy Partial resection of anterior papillary muscle
17 (74) 17 (74) 9 (39) 3 (13) 3 (13) 2 (9) 2 (9) 1 (4)
AV: atrioventricular; LVOTO: left ventricular outflow tract obstruction. In most patients, the surgery for relief of LVOTO was complex and required intervention on several different structures.
methods used for correction of LVOTO are summarized, and in Fig. 1, schema of individual procedures are demonstrated. Excision of the membrane represented the most important procedure for relief of LVOTO in 16 (70%) patients and myectomy in 3 (12%) patients. Excision of the left AV valve and valve replacement with a mechanical valve was required in 2 (9%) patients with unfavourable anatomy of AV valves and hypertrophic papillary muscles, which obstructed the path between the inflow and the outflow part of the left ventricle and caused LVOTO. In 1 (4%) patient who had very long and hypertrophic anterolateral papillary muscle, it was necessary to mobilize attachments of the papillary muscle to the septum and free wall, and to thin the obstructive myocardial mass by partial resection of this papillary muscle. In 3 (12%) patients, pulmonary valvotomy was performed, and in one of them, enlargement of the right ventricular outflow tract with a monocusp transannular patch was required.
ORIGINAL ARTICLE
Table 2: Morphology
792
T. Tlaskal et al. / Interactive CardioVascular and Thoracic Surgery
Figure 1: Methods of the left ventricular outflow tract repair in patients with atrioventricular septal defect. (a) Excision of a fibromuscular membrane and radical myectomy. (b) Mobilization and partial resection of a hypertrophic anterior papillary muscle obstructing the left ventricular outflow tract. (c) Excision of the left atrioventricular valve. Hypertrophic anterior papillary muscle caused severe left ventricular outflow tract obstruction, which could not be released. The left atrioventricular valve was replaced with a mechanical valve.
Postoperative mortality Table 4: One (4%) patient died early and 1 (4%) patient died late from heart failure, both deaths occurred before 1995. Both patients who died had partial AVSD with very unfavourable morphology of the left AV valve. The first child also had valvar pulmonary stenosis, small pulmonary annulus and anomalous attachments of the left AV valve in LVOT. This complex anatomy was associated with severe biventricular hypertrophy. At repair, the right ventricular obstruction was released by transannular patch with a monocusp pericardial valve. The subaortic obstruction caused by anomalous attachments of the left AV valve could not be released. The child died 6 days after surgery. The late mortality occurred in a 6-year old girl with a stenotic left AV valve. The hypertrophic papillary muscles caused low-laying localized LVOTO. The repair required the left AV valve replacement. This procedure improved LV inflow and released the LVOTO. The girl suffered, however, from arrhythmias and left heart failure, which led to her death 3 years after the repair. Insignificant difference in mortality between partial and complete AVSD was found (2 of 16 patients or 13% in partial vs 0 of 7 patients or 0% in complete AVSD, P = 0.51).
Follow-up After repair of AVSD with LVOTO in 23 patients, the clinical condition of 21 (91%) children improved. During the follow-up, however,
Reoperations
Procedure
n
Resection of fibromuscular membrane Left AV valve replacement Plasty of left AV valve Pacemaker implantation Excision of anomalous valvar tissue Residual VSD closure Residual ASD closure Resection of coarctation of the aorta
5 3 2 2 1 1 1 1
ASD: atrial septal defect; AV: atrioventricular; VSD: ventricular septal defect.
recurrence and progression of LVOTO was observed in 9 (41%) patients, and in 6 of them, reoperation was necessary (Table 4). The average gradient across LVOT before reoperation was 76 ± 10 mmHg (range 65–90). The reoperation for subvalvar AS was performed at a median age of 9.7 years (mean 10.1 ± 3.3 years, range 5.8–15.5 years), and a median of 6.5 years (6.3 ± 3.2 years, range 2.7–12.2 years) after surgery for LVOTO. In 5 reoperated children, the surgery consisted in excision of fibromuscular membrane and myectomy. In 1 patient, excision of anomalous left AV valve attachments was also required. In another reoperated child, it was
necessary to excise the left AV valve together with papillary muscles that caused the subaortic obstruction. In 2 reoperated patients, plasty of the left AV valve was also required. Six other reoperations were required in 4 patients. Table 4 summarizes all 16 surgical procedures performed as reoperations in 10 patients. Today, 21 (91%) patients remain in New York Heart Association functional Class I or II, median 5.2 years (mean 6.0 ± 5.5 years, range 0–18.4 years) after surgery. The actuarial survival (expressed by the Kaplan–Meier estimate) in patients with AVSD and LVOTO was 96, 88 and 88%, respectively, at 1, 10 and 15 years after surgery for LVOTO. The survival without reoperation for LVOTO is median 3.0 years (mean 4.4 ± 4.3 years, range 0–17.7 years). In the group of 22 early survivors the actuarial freedom from reoperation for LVOTO at 1, 6, 10 and 15 years, respectively, after surgery for LVOTO is 100, 80, 40 and 20%, respectively. However, the systolic pressure gradient across LVOT gradually rose in 3 (14%) other patients and reached 56, 45 and 41 mmHg, respectively. All these 3 patients originally had dysplastic left AV valve.
Limitations of the study The relative rarity and morphological variability of LVOTO in the association with AVSD resulted in small sample sizes of all individual subgroups of patients in this cohort of operated patients. Any meaningful statistical analysis is therefore limited.
DISCUSSION AVSD represents morphologically an extremely variable congenital heart disease. Prolongation and narrowing of LVOT represent typical characteristics of all hearts with AVSD, but in some hearts, potential or unequivocal LVOTO can be detected [2, 3, 7–10]. Preoperatively, real LVOTO with a significant pressure gradient is rare. Morphological changes of all structures forming LVOT may, however, increase the risk of damasking stenosis after the repair [11, 13]. These changes include more extensive deficiency of the outlet septum, hypertrophy of the LV free wall and septum, accessory left AV valvar tissue, hypertrophic and/or more anteriorly and superiorly attached anterolateral or accessory papillary muscle, thick chordae attached more to the left and inside LVOT, hypertrophic anterolateral muscle band, anomalous fibrous strands in LVOT and aortic valvar anomalies [2, 8, 14, 16, 17]. The changes in the left superior bridging leaflet tissue quality and abnormal septal attachments may add significant risk of LVOTO particularly in hearts with separate orifices and in Type A of the complete AVSD. A very important role in formation of LVOTO is probably played by anomalies of AV valves during the natural history or after the repair of AVSD [14, 16]. Dysplastic AV valve, anomalous attachments with dense fibrous tissue, multiple secondary chordae, fibrous strands between the leaflet and the crest of the interventricular septum, closure of a wide, irregular or anteriorly oriented ‘cleft’ may compromise the valve mobility and narrow the space below the aortic valve. The primary LVOTO is often caused by anomalies of the left AV valve and their attachments, which may provoke turbulence, and formation of a fibrous scar tissue. The fibromuscular membrane develops as a secondary structure in a region of increased blood turbulence in an irregular and anatomically narrow LVOT [11, 12]. The true prevalence of LVOTO in AVSD is not clear. In different series of heart specimens, the incidence is higher than in clinical
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series, where it is usually
