Author + information
- Received November 21, 1996
- Revision received March 24, 1997
- Accepted April 16, 1997
- Published online August 1, 1997.
- ↵*Dr. Steven D. Colan, Department of Cardiology, Children’s Hospital, 300 Longwood Avenue, Boston, Massachusetts 02115.
Objectives. We reviewed our institutional experience with anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) after dual coronary repair to assess preoperative variables predictive of outcome, the time course for postoperative recovery of cardiac function, the short- and long-term complications and our experience with left ventricular assist devices (LVAD) in these patients.
Background. Outcome after surgical repair of ALCAPA remains incompletely defined.
Methods. The surgical records and echocardiograms of 42 patients were reviewed. Left ventricular function was assessed by fractional shortening z-score (FSz) and stress-velocity index.
Results. The overall survival rate was 86%. All six patients who died were <1 year old and died within 3 days of the operation. More severe preoperative mitral regurgitation (MR) was associated with increased mortality, but age, body surface area, preoperative FSz and end-diastolic dimension were not. We used an LVAD for 7 of 28 patients who underwent repair for ALCAPA since its introduction at our institution, with a survival of 5 of 7 patients. The degree of MR improved in 62% of patients and remained unchanged in 38%. Complications included supravalvar pulmonary stenosis (16 of 21 patients) and baffle leaks (11 of 21 patients) with the intrapulmonary baffling technique. Supravalvar pulmonary stenosis developed in 1 of 11 patients after direct coronary reimplantation. Left ventricular function became normalized in all 28 patients with follow-up past 1 year, regardless of preoperative FSz. Of 13 patients who underwent serial postoperative echocardiography, the average time to normalization of function was 2 to 7 months.
Conclusions. The degree of preoperative MR was predictive of outcome, whereas the severity of preoperative cardiac dysfunction and ventricular dilation were not. Mild and moderate MR tended to improve without mitral valvuloplasty. Complete recovery from myocardial dysfunction is expected after dual coronary repair of ALCAPA.
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital anomaly that usually presents in infancy with congestive heart failure due to ischemic left ventricular (LV) dysfunction and has high mortality without surgical repair [1–3]. Survival was improved by ligation of the anomalous left coronary artery to eliminate steal to the pulmonary artery; however, the surgical and late mortality rates remained high [3–6]. Multiple techniques have been implemented to establish a dual coronary circulation, including coronary artery bypass grafting, coronary baffling procedures and direct reimplantation of the left coronary artery to the aorta [7–14]. The outcome after surgical repair of ALCAPA remains incompletely defined, and transplantation has been suggested and reportedly performed in patients with severe LV dysfunction at presentation .
We reviewed our institutional experience with ALCAPA in which a dual coronary circulation had been surgically established to assess 1) preoperative variables predictive of outcome; 2) the time course for recovery of cardiac function after surgical repair; 3) the short- and long-term postoperative complications of the current operative techniques; and 4) our experience with left ventricular assist devices (LVADs) in the immediate postoperative management.
Patients diagnosed with ALCAPA were selected from our institutional data base. Patients who had an anomalous left main coronary artery from the pulmonary artery and who underwent a dual coronary repair at our institution were included for study. Early cases in which the left coronary artery was ligated were excluded. One patient with an anomalous left circumflex coronary artery was also excluded. Surgical records and all echocardiograms were reviewed for the study group.
Left ventricular function at presentation was assessed by fractional shortening (FS) obtained from M-mode echocardiography in the parasternal short-axis view. Fractional shortening and end-diastolic dimension (EDD), adjusted for age and body surface area, respectively, were compared with normal echocardiographic data to derive z-scores (FSz and EDDz) (standard deviations from normal mean value).
Postoperative LV performance was evaluated by FS; contractility was also measured in patients followed at our institution after 1990. Although FS is influenced by preload and afterload, the rate-corrected velocity of circumferential fiber shortening (VCFc) is only affected by afterload, which can be measured as end-systolic wall stress. Therefore, the stress-velocity index (SVI), which is the relation between VCFc and end-systolic stress, was used as an index of contractility . The M-mode of the LV was recorded with the carotid or axillary pulse tracing, heart sounds and electrocardiogram. The pulse tracing was corrected for time delay by aligning the dicrotic notch with end-systole, defined as the first high frequency component of the second heart sound. The LV endocardial and epicardial surfaces and the pulse tracing were digitized, and the data were averaged from three beats. End-systolic stress was derived from the equation: 1.35 × P × D/4(WT)[1 + (WT/D)], where P = pressure at the dicrotic notch; D = LV end-systolic diameter; and WT = LV end-systolic wall thickness. Ejection time (ET) was measured from the carotid pulse tracing and corrected for heart rate by dividing by the square root of the RR interval. The VCFc was then calculated as VCFc = SF/ETc. The SVI was then obtained as the z-score of the VCFc–end-systolic stress relation relative to the age-appropriate distribution in normal subjects . Qualitative assessment was made for regional wall motion abnormalities.
Because of the time course encompassed by the study, the method of assessing the severity of mitral regurgitation (MR) was not uniform. The degree of MR was evaluated by pulsed Doppler mapping of the atrial jet, color Doppler regurgitant area and retrograde pulmonary vein Doppler, and more recently by the proximal regurgitant jet width relative to the mitral annulus size using color Doppler echocardiography. The assessment of the degree of MR made by the original echocardiographer—categorized as not present, mild, moderate or severe—was accepted without further review. This approach was taken to minimize the risk of introducing bias. Postoperative supravalvar pulmonary stenosis gradients were assessed by pulsed and continuous wave Doppler echocardiography. Baffle leaks were sought with color Doppler echocardiography.
1.3 Statistical analysis.
Chi-square analysis was used to evaluate early age at the time of the operation, as a risk factor for survival. Analysis of variance was used to assess the relation of preoperative MR to preoperative FSz and EDDz, and the relation of preoperative FSz and EDDz, age and body surface to mortality for infants <1 year old. The Fisher exact test was used to assess the relation of MR to mortality for these infants. Preoperative FSz was compared with ultimate FSz and SVI using linear correlation analysis. Statistical significance was set at p ≤ 0.05.
Forty-two patients were diagnosed with ALCAPA between the years 1977 and 1995 at our institution who underwent dual coronary repair. At the time of diagnosis and surgical repair, 33 patients were <1 year of age and nine patients were 1 to 13 years old. One patient diagnosed with ALCAPA at 8 months had undergone neonatal repair of aortic coarctation. No other patient had associated structural heart disease. There were 25 female patients and 17 male patients.
2.2 Surgical techniques.
Fourteen patients underwent direct reimplantation of the left coronary artery to the aorta, including a rim of surrounding pulmonary artery wall. The defect in the pulmonary artery was repaired using a pericardial patch. One of these patients required pericardial augmentation to extend the length of the left coronary artery and to patch the pulmonary artery defect.
Twenty-six patients underwent an intrapulmonary baffling technique to a created aortopulmonary window . Many of these patients underwent this operation in the earlier part of the series, before coronary reimplantation was commonly performed. One of these patients underwent mitral valvuloplasty at the time of ALCAPA repair.
Two patients underwent a modified baffling technique in which an extrapulmonary baffle was fashioned from the anterior and posterior walls of a transected segment of the pulmonary artery adjacent to the left coronary artery, and the proximal and distal pulmonary arteries were reanastomosed .
In the latter part of this series, myocardial protection included snaring the pulmonary arteries immediately after commencing bypass to prevent steal from the coronary arteries into the decompressed pulmonary artery and to ensure that cardioplegia solution was delivered to both the right and left coronary beds. Usually the main pulmonary artery was seen to fill rapidly with cardioplegia solution because of the presence of collateral connections between the right and left coronary systems, and it has generally not been necessary to infuse cardioplegia separately into the left coronary system .
2.3 Preoperative function.
Preoperative echocardiograms were performed in 35 patients. The mean preoperative FSz for infants <1 year old was −11.3 ± 2.5, and for older children it was −2.4 ± 2.9. Mitral regurgitation was found preoperatively in a total of 27 patients (mild in 16, moderate in 8 and severe in 3, including 1 with severe prolapse of the anterior mitral valve leaflet). The degree of preoperative MR did not correlate with the severity of LV dysfunction or EDD.
All six deaths occurred within 3 days of the operation, four of which were on the day of the procedure. There was no significant difference in survival among the surgical techniques implemented (left coronary artery reimplantation 11 [79%] of 14, intrapulmonary baffling technique in 23 [88%] of 26, modified extrapulmonary baffle in 2 (100%) of 2), with an overall survival rate of 86%.
All the patients who died were <1 year old; however, the difference in survival of these infants compared with older patients did not achieve statistical significance because of the small number of patients in the older age group (p = 0.2). For the infants, age, body surface area and preoperative FSz and EDDz did not predict mortality (p = 0.4, 0.3, 0.8 and 0.1, respectively). Higher degree of MR was a risk factor for mortality (p = 0.034). The mortality rate for infants with no MR or mild MR was 5% (0 of 6 and 1 of 13, respectively), and with moderate or severe MR it was 40% (3 of 7 and 1 of 3, respectively). One infant who died did not have a preoperative echocardiogram.
2.5 Experience with LVAD.
The LVAD was first used for postoperative management of ALCAPA at our institution in 1987. Since then, 25% (7 of 28) of patients who underwent repair for ALCAPA were placed on a LVAD when they were unable to be weaned from bypass or judged by the surgeon to be likely to die imminently. A Biomedicus centrifugal pump was used in all seven patients in this series. Of these patients, five survived after 1, 2 and 3 days on a LVAD (1 patient, 1 patient and 3 patients, respectively). One patient died on the day of surgical repair while on a LVAD, and one patient died on the third postoperative day, several hours after LVAD was withdrawn. One other patient who survived was placed on extracorporeal membrane oxygenation 4 days postoperatively for 28 days because of a concurrent respiratory syncytial virus infection.
2.6 Postoperative complications.
In the 21 patients who underwent an intrapulmonary coronary baffling procedure for whom postoperative echocardiographic data were available, supravalvar pulmonary stenosis was the most common long-term postoperative complication. A mild gradient ≤25 mm Hg was seen in eight patients, a moderate gradient 26 to 50 mm Hg in five patients and a severe gradient >50 mm Hg in three patients. Two patients with severe supravalvar pulmonary stenosis underwent reoperation to relieve the obstruction. One patient developed mild supravalvar pulmonary stenosis after reimplantation of the left coronary artery into the aorta (n = 11) in which a large pulmonary artery segment was necessary for coronary transfer. No supravalvar pulmonary stenosis was found at follow-up after an extrapulmonary baffling procedure.
Baffle leaks resulting in a residual left to right shunt were found in 11 of 21 patients after an intrapulmonary baffling procedure, three of whom underwent reoperation to repair these defects. This complication is not applicable to the other two ALCAPA repair techniques.
One patient had progressive aortic regurgitation after an intrapulmonary baffling repair, eventually undergoing an aortic valve replacement. In addition, one other patient had baffle occlusion documented by angiography 2 years postoperatively. The left coronary artery filled retrogradely from the right coronary artery, and the LV was noted to be dilated and hypocontractile on angiography. No echocardiogram was performed for this patient.
2.7 Postoperative function.
Postoperative echocardiograms were available for review in 34 patients. The follow-up period for these patients was 1 week to 12 years (mean 3.7 years).
Preoperative FSz did not predict ultimate LV function. Global LV function, as assessed by SVI or FSz, or both, became normalized in all 28 patients with patent dual coronary systems for whom follow-up is known past 1 year, regardless of the preoperative FSz. The time course for recovery of FSz, EDDz and end-systolic stress z-score is shown in Fig. 1. For echocardiograms in which SVI was assessed, a close relation with FSz was seen after the early postoperative period. The difference between FSz and SVI in the early postoperative period is the anticipated result of abnormal loading conditions prevalent during that period. Regional wall motion abnormalities assessed by qualitative analysis were not detected in any of the patients.
To further describe the time course of recovery of LV function and EDD, 13 patients repaired under 1 year old who underwent serial postoperative echocardiography were examined separately (Fig. 2). Of these patients, the average time to normalization of LV function was between 2 and 7 months after repair. For patients <1 year with severe preoperative LV dysfunction, improvement in function was seen as early as 1 week postoperatively. Continued recovery of function was seen as late as 2 years.
In the 15 patients who survived, mild preoperative MR remained mild in six (40%) and resolved in nine (60%). Moderate preoperative MR (n = 8) remained moderate in one patient and became mild in four patients; three patients died. Of the three patients with severe preoperative MR, one died, one was lost to follow-up and the other continued to have severe MR with the echocardiographic appearance of severe prolapse of the anterior mitral valve leaflet 2 months after the operation. This patient underwent mitral valvuloplasty at that time. Direct inspection of the mitral valve revealed anterior leaflet prolapse due to severe elongation of a major chordae from the septal papillary muscle that was shortened surgically. The one patient who had mitral valvuloplasty at the time of ALCAPA repair did not have a preoperative echocardiogram. This patient had moderate MR postoperatively.
The overall survival rate after dual coronary repair of ALCAPA at our institution is 86%. All deaths occurred within 3 days of the operation. Severity of preoperative MR was a risk factor for mortality, whereas the severity of preoperative cardiac dysfunction in patients with ALCAPA did not predict mortality or recovery of LV function. Although all the deaths were in patients <1 year of age (82% survival rate for infants), young age at the time of surgical repair did not reach statistical significance as a risk factor for mortality, possibly because of the small number of older children in our series. Our experience is in contrast with that of other investigators who have reported that the severity of preoperative LV dysfunction was a significant risk factor for mortality, although the degree of MR and age were not [15, 18]. Sauer et al. concluded that early age at operation, regardless of the type of coronary pattern, was a significant risk factor for mortality. This is probably related to the significant risk associated with early age at presentation and does not imply an advantage to postponing the operation when the diagnosis of ALCAPA is made at an earlier age, as has been suggested in the past [3, 18, 20]. Some stable patients who were thought to be unfavorable surgical candidates because of their young age died while awaiting “elective” surgical repair at an older age [21, 22]. Presentation at a young age likely represents more severe myocardial ischemia and LV dysfunction. Patients who are either diagnosed or have waited for the procedure until after 2 years of age are probably a different cohort with more developed collateral coronary circulation .
3.2 Left ventricular assist device.
Children with ALCAPA represent a unique group with predominantly LV dysfunction, often transiently exacerbated by cardiopulmonary bypass. Therefore, they are ideal candidates for successful use of a LVAD when separation from bypass cannot be achieved. The LVAD was used in 25% of our patients with ALCAPA since 1987. The high survival rate of 71% after LVAD placement for our patients with ALCAPA was similar to that of previous reports [23–26]. These patients presumably would have died in the operating room or soon after had a LVAD not been available. The use of a LVAD for these patients may allow for some recovery of LV function in the early postoperative period. Although small changes in FS are impossible to measure accurately when there is severe LV dysfunction, obvious improvement in LV function was observed in some patients by 1 week postoperatively.
3.3 Postoperative complications.
Postoperative complications for the intrapulmonary baffling procedure included supravalvar pulmonary stenosis in 16 (76%) of 21 patients and baffle leaks in 11 (52%) of 21 patients, with reoperation performed in 4 (19%) of 21 patients after this operative technique. Postoperative supravalvar pulmonary stenosis after direct left coronary artery reimplantation was found in 22% of patients in one series . In our series, we found this complication to be significantly less common, with mild suprapulmonary stenosis in one patient after left coronary artery reimplantation. We found no postoperative complications after an extrapulmonary baffling technique. The extrapulmonary baffling technique has not yet been extensively performed at our institution in patients in whom direct left coronary artery reimplantation was not possible. Although the incidence of supravalvar pulmonary stenosis should be reduced from that found after the intrapulmonary baffling technique, long-term follow-up is necessary to show a definite advantage.
3.4 Mitral regurgitation.
Primary repair of the mitral valve in patients with MR associated with ALCAPA is controversial. Mitral regurgitation in survivors followed postoperatively was reduced by one severity level in 62% of patients or remained unchanged in 38%. Our data show that mild and moderate MR usually improves concomitant with postoperative recovery of LV function. It is likely that MR results, in part, from distortion of the mitral valve annulus with severe LV dilation and from selective ischemia to the susceptible papillary muscles during hypoperfusion. Both mechanisms are usually reversed after surgical repair. However, it remains possible that patients with severe preoperative MR would have a better outcome and would avoid an additional operation if the mitral valve were repaired at the time of coronary revascularization. Good results have been reported with a minimal increase in cross-clamp time [21, 26].
3.5 Recovery of LV function.
Our findings of normalization of LV function in all patients with ALCAPA and a patent two-vessel repair, regardless of the severity of preoperative dysfunction, concur with those of other investigators who have used echocardiography and radionuclide myocardial perfusion under rest and stress conditions [15, 26, 27]. Many patients in our series showed improvement of LV function within 1 month of the procedure, and 50% of patients repaired under 1 year old who were followed with serial echocardiograms had normalized function by 2 to 7 months. A possible mechanism for the recovery of cardiac function after repair is myocyte hyperplasia in young patients. In addition, there may be compensatory hypertrophy of remaining viable myocytes if muscle necrosis occurs. Alternatively, the potential for complete myocardial recovery after revascularization following chronic myocardial ischemia in these patients may be explained by the phenomenon of hibernation. Hibernating myocardium specifically refers to the occurrence of persistent contractile dysfunction associated with chronic ischemia but preserved myocardial viability . It has been suggested that the chronic myocardial hypoperfusion of ALCAPA leads to myocyte adaptation rather than diffuse infarction. Shivalkar et al. observed significant histologic evidence of ultrastructural alterations in viable myocytes from cardiac biopsy specimens of patients with ALCAPA before revascularization, when compared with the cardiac biopsy specimens of control subjects. The finding of complete recovery of LV function in these patients without evidence of infarction supports this hypothesis. The occasionally prolonged recovery may represent a gradual reversal of these adaptive cellular changes. Cardiac dysfunction may be acutely compounded by postoperative myocardial stunning, the transient mechanical dysfunction that persists after reperfusion and restoration of normal coronary blood flow . Myocardial stunning may contribute to some patients’ dependence on a LVAD in the immediate postoperative period and to its successful discontinuation within days of the operation.
Normal LV ejection fraction, as assessed by technetium-99m cardiac pool imaging and echocardiography, has been found consistently in all patients postoperatively, but perfusion defects of the anterior and anterolateral segments have been seen in these patients after stress testing using thallium-201 imaging [27, 31]. Stern et al. found that perfusion defects on thallium-201 imaging were seen more frequently in patients who had undergone repair at an older age, giving further support for early surgical intervention. In addition, Paridon et al. found exercise-induced electrocardiographic changes in patients postoperatively, despite normal thallium scanning, which they thought might be explained by the limited capacity of thallium scintigraphy to detect isolated subendocardial ischemia. Although we documented normal global function under rest conditions, possible cellular level abnormalities cannot be excluded based on this analysis. However, the implications of minor perfusion abnormalities seen on radionuclide scans are unclear. Similar findings in a large patient group with transposition of the great arteries after the arterial switch operation were not found to be clinically important and were not associated with regional wall motion abnormalities . We found no qualitative evidence of regional wall motion abnormalities in the patients with ALCAPA. Rein et al. have shown that even before repair, infants with ALCAPA exhibit global hypokinesia, suggesting diffuse hypoperfusion rather than regional wall motion abnormalities typical of segmental ischemia or infarction, or both.
3.6 Study limitations.
The quantitative reliability of Doppler echocardiography for determining the degree of MR is uncertain, particularly given the technologic evolution encompassed by this study. The impact of the random error would not be expected to bias the results, but would instead weaken our ability to recognize the impact of MR on the outcome.
The estimated time course for normalization of LV function may have been biased by the selection of the 13 patients followed with serial postoperative echocardiograms. Serial echocardiograms were obtained only in patients followed at our institution, at the discretion of the individual cardiologists caring for the patients. Only patients repaired under 1 year old were selected for this analysis. This age group had the poorest preoperative LV function, but possibly the highest capacity for recovery.
1) The current operative survival for ALCAPA does not justify consideration of cardiac transplantation. 2) The degree of preoperative MR is predictive of outcome, whereas the severity of preoperative cardiac dysfunction and the magnitude of ventricular dilation are not. 3) A LVAD appears to improve survival for patients with ALCAPA and should be available for postoperative management. 4) After an intrapulmonary baffling procedure, the majority of patients develop supravalvar pulmonary stenosis and several develop baffle leaks; many patients require reoperation for these complications. An extrapulmonary baffling technique should reduce the incidence of postoperative supravalvar pulmonary stenosis in patients for whom direct coronary reimplantation is not possible. 5) Mild preoperative MR tends to improve after repair of ALCAPA without mitral valvuloplasty. The most appropriate operative management of patients with moderate or severe MR is not clear. 6) Normalization of cardiac function is expected in all operative survivors with a patent dual coronary system.
- anomalous origin of left coronary artery from pulmonary artery
- end-diastolic dimension
- end-diastolic dimension z-score
- fractional shortening
- fractional shortening z-score
- left ventricle, left ventricular
- left ventricular assist device
- mitral regurgitation
- stress-velocity index
- corrected velocity of circumferential fiber shortening
- Received November 21, 1996.
- Revision received March 24, 1997.
- Accepted April 16, 1997.
- The American College of Cardiology
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