An institutional experience with second- and third-stage palliative procedures for hypoplastic left heart syndrome: the impact of the bidirectional cavopulmonary shunt

Role of surgeon intuition and computer-aided design in Fontan optimization: A computational fluid dynamics simulation study

OBJECTIVE

Customized Fontan designs, generated by computer-aided design (CAD) and optimized by computational fluid dynamics simulations, can lead to novel, patient-specific Fontan conduits unconstrained by off-the-shelf grafts. The relative contributions of both surgical expertise and CAD to Fontan optimization have not been addressed. In this study, we assessed hemodynamic performance of Fontans designed by both surgeon's unconstrained modeling (SUM) and by CAD.

METHODS

Ten cardiac magnetic resonance imaging datasets were used to create 3-dimensional (3D) models of Fontans. Baseline computational fluid dynamics simulations assessed Fontan indexed power loss (iPL), hepatic flow distribution, and percentage of conduit surface area with abnormally low wall shear stress for venous flow (<1 dyne/cm²). Fontans not meeting thresholds were redesigned using 2 methods: SUM (ie, original venous anatomy without the Fontan was 3D printed and sent to surgeon for Fontan redesign with clay modeling) and CAD (ie, the same 3D geometry was sent to engineers for iterative Fontan redesign guided by computational fluid dynamics). Both groups were blinded to each other's results.

RESULTS

Eight Fontans were redesigned by SUM and CAD methods. Both SUM and CAD redesigns met iPL thresholds. SUM had lower iPL, whereas CAD demonstrated balanced hepatic flow distribution and lower wall shear stress percentage. Wall shear stress percentage shared an inverse relationship with iPL, preventing oversized Fontan designs.

CONCLUSIONS

Customized Fontan conduits with low iPL can be created by either a surgeon or CAD. CAD can also improve hepatic flow distribution and prevent oversized Fontan designs. Future studies should investigate workflows that combine SUM and CAD to optimize Fontan conduits.

Hemodynamic effects of left pulmonary artery stenosis after superior cavopulmonary connection: a patient-specific multiscale modeling study

OBJECTIVE

Currently, no quantitative guidelines have been established for treatment of left pulmonary artery (LPA) stenosis. This study aims to quantify the effects of LPA stenosis on postoperative hemodynamics for single-ventricle patients undergoing stage II superior cavopulmonary connection (SCPC) surgery, using a multiscale computational approach.

METHODS

Image data from 6 patients were segmented to produce 3-dimensional models of the pulmonary arteries before stage II surgery. Pressure and flow measurements were used to tune a 0-dimensional model of the entire circulation. Postoperative geometries were generated through stage II virtual surgery; varying degrees of LPA stenosis were applied using mesh morphing and hemodynamics assessed through coupled 0-3-dimensional simulations. To relate metrics of stenosis to clinical classifications, pediatric cardiologists and surgeons ranked the degrees of stenosis in the models. The effects of LPA stenosis were assessed based on left-to-right pulmonary artery flow split ratios, mean pressure drop across the stenosis, cardiac pressure-volume loops, and other clinically relevant parameters.

RESULTS

Stenosis of >65% of the vessel diameter was required to produce a right pulmonary artery:LPA flow split <30%, and/or a mean pressure drop of >3.0 mm Hg, defined as clinically significant changes.

CONCLUSIONS

The effects of <65% stenosis on SCPC hemodynamics and physiology were minor and may not justify the increased complexity of adding LPA arterioplasty to the SCPC operation. However, in the longer term, pulmonary augmentation may affect outcomes of the Fontan completion surgery, as pulmonary artery distortion is a risk factor that may influence stage III physiology.

Risk factors for prolonged length of stay after the stage 2 procedure in the single-ventricle reconstruction trial

BACKGROUND

The single-ventricle reconstruction trial randomized patients with single right ventricle lesions to a modified Blalock-Taussig or right ventricle-to-pulmonary artery shunt at the Norwood. This analysis describes outcomes at the stage 2 procedure and factors associated with a longer hospital length of stay (LOS).

METHODS

We examined the association of shunt type with stage 2 hospital outcomes. Cox regression and bootstrapping were used to evaluate risk factors for longer LOS. We also examined characteristics associated with in-hospital death.

RESULTS

There were 393 subjects in the analytic cohort. Median stage 2 procedure hospital LOS (8 days; interquartile range [IQR], 6-14 days), hospital mortality (4.3%), transplantation (0.8%), median ventilator time (2 days; IQR, 1-3 days), median intensive care unit LOS (4 days; IQR, 3-7 days), number of additional cardiac procedures or complications, and serious adverse events did not differ by shunt type. Longer LOS was associated (R(2) = 0.26) with center, longer post-Norwood LOS (hazard ratio [HR], 1.93 per log day; P < .001), nonelective timing of the stage 2 procedure (HR, 1.78; P < .001), and pulmonary artery (PA) stenosis (HR, 1.56; P < .001). By univariate analysis, nonelective stage 2 (65% vs 32%; P = .009), moderate or greater atrioventricular valve (AVV) regurgitation (75% vs 24%; P < .001), and AVV repair (53% vs 9%; P < .001) were among the risk factors associated with in-hospital death.

CONCLUSIONS

Norwood LOS, PA stenoses, and nonelective stage 2 procedure, but not shunt type, are independently associated with longer LOS. Nonelective stage 2 procedure, moderate or greater AVV regurgitation, and need for AVV repair are among the risk factors for death.

Effect of race on the timing of the Glenn and Fontan procedures for single-ventricle congenital heart disease

OBJECTIVE

Disparities in health care have been documented between different racial groups in the United States. We hypothesize that there will be racial variance in the timing of the Glenn and Fontan procedures for children with single-ventricle physiology.

DESIGN AND SETTING

We performed a retrospective review of a national pediatric intensive care unit database (Virtual PICU Performance System, LLC).

PATIENTS

Children with hypoplastic left heart syndrome, tricuspid atresia, and common ventricle, admitted from January 2006 to July 2008, were included. Data included race, weight, age, medical length of stay, Paediatric Index of Mortality 2 score, and survival.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 423 patients from 29 hospitals. The study population was 7.6% black, 13.0% Hispanic, 59.8% white, 9.2% "other," and 11.6% had missing racial/ethnic information. Diagnoses included 255 patients with hypoplastic left heart syndrome, 91 with tricuspid atresia, and 77 with common ventricle. The median age for the Glenn procedure (n = 205) was 5.5 months (interquartile range, 4.6-7.0 months) and 39.7 months (interquartile range, 32.4-50.6 months) for the Fontan procedure (n = 218). There was no difference between the median age at the time of the Glenn or Fontan procedures between the different racial/ethnic groups (p = .65 and p = .16, respectively). The medical length of intensive care unit stay for patients receiving the Glenn and Fontan procedures was 3.7 days (interquartile range, 1.9-6.1 days) and 3.7 days (interquartile range, 1.9-6.8 days), respectively. There were no differences in medical length of intensive care unit stay for the Glenn procedure between the different racial/ethnic groups (p = .21). Hispanic patients had a longer medical length of intensive care unit stay (6.3 days; interquartile range, 3.1-9.9 days) than white patients (2.9 days; interquartile range, 1.8-5.3 days) for the Fontan procedure (p = .008).

CONCLUSION

The timing of single-ventricle palliative procedures was not affected by race/ethnicity.

Primary in-series palliation of hypoplastic left heart syndrome with mechanical lung assist in neonatal pigs

Less than optimal outcomes for hypoplastic left heart syndrome may be related to unstable in-parallel circulation. Mechanical lung assist by (1) superior vena cava to right atrium pump with oxygenation (oxygenator assist), or (2) superior vena cava to pulmonary artery pump (pump assist) may permit successful neonatal in-series palliation. Nineteen 15-day-old piglets underwent single ventricle and bidirectional cavopulmonary shunt (BCPC) creation without mechanical lung assist (n = 8), with pump assist (n = 5), or with oxygenator assist (n = 6). Baseline hemodynamic measurements were not different between groups. Median survival for the cavopulmonary shunt alone, pump assist, and oxygenator assist groups was 28, 180, and 180 minutes, respectively (p = 0.0006). No differences in arterial oxygen concentration or bicarbonate levels were detected. Arterial carbon dioxide (p < or = 0.007) was higher in the cavopulmonary shunt alone versus lung assist groups. Cavopulmonary shunt alone animals had decreased mean arterial pressure (p < 0.02) and cerebral perfusion pressure (p = 0.029) and elevated left atrial pressure compared with lung assist groups (p < 0.05). This data demonstrates creation of a novel translational neonatal BCPC model in which mechanical lung assist augments survival. Early BCPC death was related to poor ventricular function and an inability to ventilate, issues that were improved with both types of lung assist.

Evaluation of congenital left ventricular aneurysm in the fetus by velocity vector imaging

We report a case of left ventricular aneurysm evaluated using the velocity vector imaging (VVI) technique, an angle-independent method used to calculate the tissue velocity strain and strain rate on routine gray scale two-dimensional images and display the velocities of endocardial points as vectors overlaid on B-mode images. It uses a combination of speckle tracking and complex geometric analysis, allowing tracing of myocardial activity throughout the cardiac cycle. In this case, evaluation of the myocardial dynamics in the fetus by VVI was started at 27 weeks of gestation, and both the systolic and diastolic velocities and the ejection fraction in the aneurysmal segment were less than in the other segments. VVI imaging at 35 weeks of gestation showed this difference even more clearly. Postnatal VVI examination showed no significant difference between results for the systolic and diastolic velocities or ejection fraction and those obtained at the prenatal VVI examination. VVI seemed to be as useful at this time, especially for assessing ventricular systolic function, as it was for postnatal examination.

The effect of left ventricular size on right ventricular hemodynamics in pediatric survivors with hypoplastic left heart syndrome

BACKGROUND

Outcome status in patients with hypoplastic left heart syndrome (HLHS) is partially dependent on right ventricular (RV) systolic function. In other disease states, ventricular function is impacted by anatomy and physiology of the contralateral ventricle. In HLHS, it is suggested that a relatively larger left ventricular (LV) size may negatively impact RV function because it becomes a "passenger" without providing any systolic or diastolic physiologic benefit. The purpose of this study was to determine whether LV size adversely affects RV systolic function in surviving patients with HLHS.

METHODS

The hospital database was searched for all patients with HLHS and technically adequate echocardiograms born in the last 6 years and who had survived at least the Norwood procedure. LV size was assessed by echocardiographic measurement of LV end-diastolic short-axis and apical area. RV function was assessed by short-axis and apical fractional area change as well as the myocardial performance index (Tei). Measurements were made at up to 4 time points depending on duration of follow-up (1 - pre-Norwood; 2 - pre-Glenn; 3 - pre-Fontan; and 4- post-Fontan).

RESULTS

A total of 48 patients were studied. LV size showed sufficient variability in the patient population (1.0-21 cm(2)/body surface area, pre-Norwood). RV function tended to worsen across the time periods but these changes did not reach statistical significance. Regression analysis showed no effect of LV size on RV function before Norwood operation. Significant correlations existed between LV size indices and RV functional indices before Glenn shunt but these were inconsistent in the direction of their effect. Only before Fontan operation did the correlation between LV size and RV function become both consistent and statistically significant; specifically larger LV size correlated significantly with poor RV systolic function (short-axis RV fractional area change vs LV area r = -0.4, P = .03 and RV Tei vs LV area r = 0.5, P = .02). These relationships were not apparent after Fontan operation.

CONCLUSION

In surviving patients with HLHS, larger LV size does not seem to negatively impact RV function before or after Norwood procedure nor does it seem to have an adverse effect on RV function chronically (after Fontan). However, further study with larger population size will be necessary to see whether these findings remain negative and are true for nonsurvivors as well.

Right Ventricular Mechanical Dyssynchrony in Children with Hypoplastic Left Heart Syndrome

BACKGROUND

Mechanical dyssynchrony predicts response to cardiac resynchronization therapy in adults with heart failure. Children with hypoplastic left heart syndrome (HLHS) are susceptible to right ventricular (RV) failure; however, mechanical dyssynchrony has not been studied in this population with newly available methodologies. We investigated RV mechanical dyssynchrony in children with HLHS using vector velocity imaging.

METHODS

We used vector velocity imaging to quantify the SD of time to peak velocity, strain, and strain rate among 6 RV segments to define intraventricular RV synchrony in 16 children with HLHS and RV and left ventricular (LV) synchrony in 16 healthy age-matched control subjects. We further investigated relations between QRS duration and mechanical dyssynchrony and between mechanical dyssynchrony and systolic function.

RESULTS

Children with HLHS had significant RV mechanical dyssynchrony versus LV and RV control subjects (strain 37 +/- 35 vs 8 +/- 8 milliseconds, P = .003 [LV], 9 +/- 11 milliseconds, P = .005 [RV]; strain rate 31 +/- 37 vs 10 +/- 13 milliseconds, P = .04 [LV], 14 +/- 15 milliseconds, P = .09 [RV]). There was no significant relationship between QRS duration and mechanical dyssynchrony and no obvious relation between the degree of mechanical dyssynchrony and the RV fractional area of change.

CONCLUSIONS

Children with HLHS have RV mechanical dyssynchrony unrelated to surface electrocardiographic QRS duration. This may contribute to RV dysfunction and may indicate the usefulness of cardiac resynchronization therapy in this population.

The Systolic to Diastolic Duration Ratio in Children with Hypoplastic Left Heart Syndrome: A Novel Doppler Index of Right Ventricular Function

BACKGROUND

Right ventricular (RV) function is an important determinant of clinical status in children with hypoplastic left heart syndrome (HLHS). However, assessment of RV function remains challenging because of its complex morphology. We investigated the S/D duration ratio in children with HLHS as a novel index of global RV function.

METHODS

We measured systolic (S) and diastolic (D) duration using tricuspid regurgitation duration from Doppler flow, to calculate the S/D ratio in 33 children with HLHS and 33 control subjects matched for age and sex. We compared the S/D ratio between patients with HLHS and control subjects, between patients with HLHS and normal and abnormal RV function, and between patients with HLHS at different stages of palliation. We further correlated the S/D ratio with catheterization data.

RESULTS

Patients and control subjects were well matched for age (3.12 +/- 4.5 vs 3 +/- 4.5 years, not significant) sex, and heart rate (cycle length 524 +/- 179 vs 575 +/- 162 milliseconds, not significant). Patients with HLHS had a significantly higher S/D ratio than control subjects (1.65 +/- 0.85 vs 0.85 +/- 0.2, P < .0001). The S/D ratio became increasingly elevated in HLHS at higher heart rates, but not in control subjects. The S/D ratio was significantly higher in patients with HLHS and decreased RV function as compared with patients with HLHS and normal RV function (2.2 +/- 0.7 vs 1.5 +/- 0.47, P = .006), and significantly increased in patients with Norwood stage 1 versus patients with Norwood stages 2 and 3 HLHS (2.16 vs 1.4 and 1.32, respectively, P < .01 and P < .001, respectively). The S/D ratio did not correlate with catheterization-derived RV end-D pressure or cardiac index.

CONCLUSIONS

Patients with HLHS have an increased S/D ratio as a result of a shortened D and prolonged S. Measurement of the S/D duration ratio using Doppler flow is a novel method to augment assessment of global RV function in HLHS.

Early cavopulmonary anastomosis after Norwood procedure results in excellent Fontan outcome

BACKGROUND

Children with univentricular hearts and aortic arch obstruction are treated sequentially with Norwood procedure, superior cavopulmonary anastomosis (SCPA), and Fontan operation. Early SCPA results in lower initial O2 saturation and longer hospitalization, but not increased mortality. We sought to determine the impact of early SCPA on Fontan candidacy and outcomes.

METHODS

Eighty-five consecutive patients undergoing Norwood operation between January 1998 and February 2003 were divided into group 1 (SCPA at less than 4 months, n = 33) and group 2 (SCPA at more than 4 months, n = 52). Of the original cohort, 69 have undergone Fontan operation, 7 await Fontan, 1 was transplanted, 3 are not Fontan candidates, and 5 died late after SCPA. Group 1 (n = 25) and group 2 (n = 44) patients who have completed Fontan operation were compared for preoperative and perioperative variables: age, size, O2 saturation, pulmonary artery pressure and size, prevalence of tricuspid regurgitation and ventricular dysfunction, extubation rate in operating room, duration of pleural drainage, hospital stay, and discharge O2 saturation. Late functional status and ventricular function were also compared. Survival was compared for original groups 1 and 2.

RESULTS

There were no differences for any preoperative or perioperative variable, or late functional assessment. Actuarial survival at 6 years was also not different (88% +/- 5% for group 1 and 94% +/- 4% for group 2, p = 0.72).

CONCLUSIONS

Although initially more cyanotic and hospitalized longer than older peers, younger SCPA patients achieve clinical equivalence by the time of Fontan operation and afterward. We conclude that both short- and long-term outcomes support performance of early SCPA.

Impaired Power Output and Cardiac Index With Hypoplastic Left Heart Syndrome: A Magnetic Resonance Imaging Study

BACKGROUND

Unfavorable cardiac mechanics in children with hypoplastic left heart syndrome (HLHS) when compared with other single-ventricle defects may affect long-term morbidity and outcome. Using noninvasive phase contrast magnetic resonance imaging (PC MRI), we examined cardiac mechanics in children with HLHS and compared the results to other single-ventricle defects.

METHODS

Eighteen children with HLHS and 18 children with other single-ventricle defects were studied after the Fontan operation. Phase contrast MRI scans were obtained perpendicular to the ascending aorta, and flow was quantified using an in-house segmentation and reconstruction scheme. The total power output was determined using the modified Bernoulli equation along with cardiac output and systemic vascular resistance index.

RESULTS

Compared with non-HLHS congenital heart defects, children with HLHS had significantly lower power output (1.40 +/- 0.39 versus 1.78 +/- 0.38 W/m2, p < 0.004) and cardiac index (3.15 +/- 0.97 versus 4.09 +/- 1.23 L x Min(-1) x m(-2), p < 0.009) with a concomitant higher systemic vascular resistance index (28.94 +/- 11.5 versus 22.7 +/- 8.53 WU, p < 0.03) despite generating similar systolic blood pressures (112.9 +/- 22.4 versus 115.2 +/- 23 mm Hg, p > 0.05).

CONCLUSIONS

Minimally invasive measurements with PC MRI in children with HLHS showed significantly lower power output and cardiac index when compared with other single-ventricle physiologies. Abnormal aortic flow patterns may contribute to power loss and may have long-term survival and morbidity implications associated with the Fontan procedure. Elevated systemic vascular resistance index despite similar blood pressure opens avenues for therapeutic intervention for afterload reduction.

Cardiac magnetic resonance imaging after stage I Norwood operation for hypoplastic left heart syndrome

BACKGROUND

After the Norwood operation, a patient's suitability for proceeding to a bidirectional cavopulmonary connection (BCPC) is assessed by a combination of echocardiography and diagnostic cardiac catheterization. In this study, we describe the results of 37 patients who underwent cardiovascular magnetic resonance (MR) assessment before BCPC.

METHODS AND RESULTS

Cardiovascular MR and echocardiography were performed in 37 infants with hypoplastic left heart syndrome before BCPC, and the findings were compared with surgical findings. MR assessment of ventricular function and valvar regurgitation were compared with echocardiography. MR exhibited high sensitivity and specificity for identification of neoaortic (sensitivity 86%, specificity 97%) and left pulmonary artery (sensitivity 100%, specificity 94%) obstruction. Echocardiography exhibited poor sensitivity for identification of vascular stenosis. The mean right ventricular ejection fraction calculated from the MR data was 50+/-10%. There was general agreement between MR and echocardiographic measures of ventricular function, although patients with good function on echocardiography demonstrated a wide range of ejection fractions. There was good agreement between MR and echocardiography for identification of valvar regurgitation.

CONCLUSIONS

Cardiovascular MR can be used to define ventricular and valvar function and vascular anatomy in infants with hypoplastic left heart syndrome after the Norwood operation. We have shown how this information can be used to plan the BCPC and identify any revisions or additional valvar surgery.

Staged surgical management of hypoplastic left heart syndrome: a single institution 12 year experience

OBJECTIVE

To describe a 12 year experience with staged surgical management of the hypoplastic left heart syndrome (HLHS) and to identify the factors that influenced outcome.

METHODS

Between December 1992 and June 2004, 333 patients with HLHS underwent a Norwood procedure (median age 4 days, range 0-217 days). Subsequently 203 patients underwent a bidirectional Glenn procedure (stage II) and 81 patients underwent a modified Fontan procedure (stage III). Follow up was complete (median interval 3.7 years, range 32 days to 11.3 years).

RESULTS

Early mortality after the Norwood procedure was 29% (n = 95); this decreased from 46% (first year) to 16% (last year; p < 0.05). Between stages, 49 patients died, 27 before stage II and 22 between stages II and III. There were one early and three late deaths after stage III. Actuarial survival (SEM) was 58% (3%) at one year and 50% (3%) at five and 10 years. On multivariable analysis, five factors influenced early mortality after the Norwood procedure (p < 0.05). Pulmonary blood flow supplied by a right ventricle to pulmonary artery (RV-PA) conduit, arch reconstruction with pulmonary homograft patch, and increased operative weight improved early mortality. Increased periods of cardiopulmonary bypass and deep hypothermic circulatory arrest increased early mortality. Similar factors also influenced actuarial survival after the Norwood procedure.

CONCLUSION

This study identified an improvement in outcome after staged surgical management of HLHS, which was primarily attributable to changes in surgical technique. The RV-PA conduit, in particular, was associated with a notable and independent improvement in early and actuarial survival.

Late outcomes in patients with surgically treated congenital heart disease

Optimizing late outcomes should be the end result of improvements in medical and surgical care for congenital heart disease (CHD). In addition to mortality, significant morbidities after surgery for CHD need to be considered. These include the need for reintervention, cardiovascular complications, exercise limitations, neurocognitive morbidities, effects on pregnancy, difficulty obtaining insurance, need for chronic medications, and impaired functional status and quality of life. Long-term outcome studies are difficult to perform, and their interpretation is complicated by intervening changes in management. Specific discussion of long-term follow-up of tetralogy of Fallot, D-transposition of the great arteries, and hypoplastic left heart syndrome illustrates the myriad management changes over the last three decades, the challenges in predicting outcomes for recent patients, and the need for ongoing initiation of long-term follow-up studies.

Single-ventricle physiology

The patient with single-ventricle physiology presents a significant challenge to the intensive care team at all stages of management. An integrated approach that applies a working knowledge of cardiac anatomy, cardiopulmonary physiology, and the basic principles of intensive care is essential to guide management for each individual patient. This management requires cooperative and constructive involvement of surgeons, cardiologists, and intensivists, as well as a nursing and respiratory care team experienced in the management of single-ventricle patients. The outcome of each stage of palliation for single-ventricle lesions should continue to improve as new ideas are developed and as older ideas are subjected to rigorous scientific analyses.

Outcomes after the Norwood operation in neonates with critical aortic stenosis or aortic valve atresia

OBJECTIVE

This study was undertaken to determine the demographic, anatomic, institutional, and surgical risk factors associated with outcomes after the Norwood operation.

METHODS

A total of 710 of 985 neonates with critical aortic stenosis or atresia enrolled in a prospective 29-institution study between 1994 and 2000 underwent the Norwood operation. Admission echocardiograms were independently reviewed for 64% of neonates. Competing risks analyses were constructed for outcomes after Norwood operation and after cavopulmonary shunt. Incremental risk factors for outcome events were sought.

RESULTS

Overall survivals after the Norwood operation were 72%, 60%, and 54% at 1 month, 1 year, and 5 years, respectively. According to competing risks analysis, 97% of neonates reached a subsequent transition state by 18 months after Norwood operation, consisting of death (37%), cavopulmonary shunt (58%), or other state (2%, cardiac transplantation, biventricular repair, or Fontan operation). Risk factors for death occurring before subsequent transition included patient-specific variables (lower birth weight, smaller ascending aorta, older age at Norwood operation), institutional variables (institutions enrolling < or =10 neonates, two institutions enrolling >/=40 neonates), and procedural variables (shunt originating from aorta, longer circulatory arrest time, and management of the ascending aorta). Of neonates undergoing cavopulmonary shunt, 91% had reached a subsequent transition state by 6 years after cavopulmonary shunt, consisting of Fontan operation (79%), death (9%), or cardiac transplantation (3%). Risk factors for death occurring before subsequent transition included younger age at cavopulmonary shunt and need for right atrioventricular valve repair.

CONCLUSIONS

Competing risks analysis defines the prevalence of the various outcomes after Norwood operation and predicts improved outcomes with successful modification of controllable risk factors.

Noncardiac surgery in children with hypoplastic left heart syndrome

BACKGROUND/PURPOSE

Hospital mortality rate among children with hypoplastic left heart syndrome (HLHS) after cardiac repair is well documented, but comparable data after noncardiac, surgical procedures are unknown. The authors hypothesized an increasing number of noncardiac procedures were being performed on children with HLHS, less than 2 years of age, from 1988 to 1997, and that these procedures were associated with a substantial mortality rate.

METHODS

A retrospective review of hospital discharge data for 2,457 children less than 2 years of age with HLHS for 1988 through 1997 was performed. The authors examined the outcomes of HLHS children undergoing only noncardiac surgical procedures during their hospital stay. Differences in hospital mortality rates between 1988 through 1992 versus 1993 through 1997 were assessed using the Chi2 square statistic.

RESULTS

Nineteen percent of the 147 children with HLHS undergoing noncardiac, surgical procedures died (95% CI, 13% to 25%). Comparing the 2 study periods, there was no significant change in outcome among HLHS children undergoing noncardiac, surgical procedures (78% v. 83%; P >.1). There was no significant difference in the percentage of hospital discharges with noncardiac, surgical procedures performed per year.

CONCLUSIONS

Although children with HLHS were not undergoing an increase in the number of noncardiac surgical procedures performed annually, even minor surgical procedures were associated with considerable mortality. Outcomes after noncardiac surgery in high-risk children with congenital heart disease warrant further investigation.

Hypoplastic left heart syndrome: diagnosis and management

The prognosis of hypoplastic left heart syndrome has improved dramatically in recent years with advances in reconstructive surgery. Many cases are now diagnosed antenatally, allowing parents time to make informed decisions about treatment options.

A comparison of treatment strategies for hypoplastic left heart syndrome using decision analysis

OBJECTIVES

We sought to identify the optimal treatment strategy for hypoplastic left heart syndrome (HLHS).

BACKGROUND

Surgical treatment of HLHS involves either transplantation (Tx) or staged palliation of the native heart. Identifying the best treatment for HLHS requires integrating individual patient risk factors and center-specific data.

METHODS

Decision analysis is a modeling technique used to compare six strategies: staged surgery; Tx; stage 1 surgery as an interim to Tx; and listing for transplant for one, two, or three months before performing staged surgery if a donor is unavailable. Probabilities were derived from current literature and a dataset of 231 patients with HLHS born between 1989 and 1994. The goal was to maximize first-year survival.

RESULTS

If a donor is available within one month, Tx is the optimal choice, given baseline probabilities; if no donor is found by the end of one month, stage 1 surgery should be performed. When survival and organ donation probabilities were varied, staged surgery was the optimal choice for centers with organ donation rates < 10% in three months and with stage 1 mortality <20%. Waiting one month on the transplant list optimized survival when the three-month organ donation rate was > or =30%. Performing stage 1 surgery before listing, or performing stage 1 surgery after an unsuccessful two- or three-month wait for transplant, were almost never optimal choices.

CONCLUSIONS

The best strategy for centers that treat patients with HLHS should be guided by local organ availability, stage 1 surgical mortality and patient risk factors.

Current management of infants and children with single ventricle anatomy

Children with single ventricle anatomy are among the most complicated and challenging patients encountered in pediatric cardiology. Current management involves staged surgical procedures, beginning with neonatal palliation and followed by a bidirectional cavopulmonary anastomosis in infancy and culminating in the Fontan procedure. The Fontan procedure, despite separating the circulation, remains a palliative procedure with many long-term concerns. This report discusses the staged surgical management of patients with single ventricle anatomy and the nursing issues relevant to each stage.

Postoperative management after the Norwood procedure

Staged reconstruction has become the preferred approach to hypoplastic left heart syndrome at many centers in the United States. The overall results of this strategy are most adversely affected by a high mortality at the initial stage, the Norwood procedure. The hemodynamic instability of a single ventricle providing blood flow in parallel to the systemic and pulmonary circulations combined with the stresses of cardiopulmonary bypass and circulatory arrest result in a precarious postoperative condition. Diligent perioperative management at this stage is essential to survival. To help simplify the complexity of single-ventricle physiology, this article describes a mathematical model that identifies the key elements that affect systemic oxygen delivery. The importance of balancing the circulation is underscored. The value of monitoring both systemic arterial and venous oxygen saturations to assess systemic-to-pulmonary blood flow ratio is derived from this mathematical model and confirmed experimentally and clinically. Recent research using animal models of single-ventricle physiology is also described. Using these concepts and information, techniques for achieving adequate systemic oxygen delivery are discussed. Copyright 1998 by W.B. Saunders Company

Unexpected death after reconstructive surgery for hypoplastic left heart syndrome

BACKGROUND

Although operative mortality for reconstructive surgery for hypoplastic left heart syndrome continues to improve, nonoperative mortality, especially in the first year of life, remains relatively high. A number of patients who are thought to be clinically well at hospital discharge die unexpectedly. The goal of the present study was to determine the incidence of and risk factors for unexpected death in patients with hypoplastic left heart syndrome.

METHODS

Retrospectively, we determined the incidence of unexpected death among 536 patients with hypoplastic left heart syndrome who were discharged to home after stage I surgical procedure. To identify potential risk factors, a nested case-control analysis was undertaken.

RESULTS

Unexpected death occurred in 22 of 536 patients (4.1%) discharged to home after stage I surgical procedure. The median age at unexpected death was 79 days (range, 25 to 227 days). Seizures preceded cardiac arrest in 2 patients, and ventricular arrhythmias were documented in 3 additional patients during attempted resuscitation. Autopsy studies were performed in 12 patients and identified residual lesions that may have contributed to death in 2 patients. In multivariate analysis documented perioperative arrhythmia and earlier year of stage I surgical procedure were associated with an increased risk for unexpected death (p = 0.03 and p = 0.04, respectively). There were 4 additional patients who had unexpected death after subsequent cavopulmonary operation at a median age of 1.6 years (range, 0.9 to 3.8 years).

CONCLUSIONS

Unexpected death occurred in more than 4% of patients with hypoplastic left heart syndrome who were discharged to home after stage I surgical procedure and was most common in the first several months of life. Factors that may contribute to unexpected death include residual lesions, arrhythmias, and neurologic events, although in the majority of cases the cause remains largely unknown.

Survival After Reconstructive Surgery for Hypoplastic Left Heart Syndrome

Background —There are limited data regarding the long-term survival of patients who have undergone reconstructive surgery for hypoplastic left heart syndrome (HLHS). We reviewed the 15-year experience at our institution to examine survival in the context of continued improvements in early operative results.

Methods and Results —Between 1984 and 1999, 840 patients underwent stage I surgery for HLHS. From review of medical records and direct patient contact, survival status was determined. The 1-, 2-, 5-, 10-, and 15-year survival for the entire cohort was 51%, 43%, 40%, 39%, and 39%, respectively. Late death occurred in 14 of the 291 patients discharged to home after the Fontan procedure, although only 1 patient has died beyond 5 years of age. Heart transplantation after stage I reconstruction was performed in 5 patients. Later era of stage I surgery was associated with significantly improved survival ( P <0.001). Three-year survival for patients undergoing stage I reconstruction from 1995 to 1998 was 66% versus 28% for those patients undergoing surgery from 1984 to 1988. Age >14 days at stage I and weight <2.5 kg at stage I were also associated with higher mortality ( P =0.004 and P =0.01, respectively). Other variables, including anatomic subtype, heterotaxia, and age at subsequent staging procedures, were not associated with survival.

Conclusions —Over the 15-year course of this study, early- and intermediate-term survival for patients with HLHS undergoing staged palliation increased significantly. Late death and the need for cardiac transplantation were uncommon.

Two-dimensional echocardiographic assessment of right ventricular function as a predictor of outcome in hypoplastic left heart syndrome

This study was undertaken to assess the importance of right ventricular function at the time of initial presentation on early and intermediate outcome in patients with hypoplastic left heart syndrome (HLHS). Several studies have attempted to define physiologic risk factors for poor early outcome following the Norwood palliation for HLHS. No clinical or hemodynamic factors including right ventricular function have been found to reliably predict Norwood I operative survival. The relation between initial ventricular function and later survival has not been investigated. To assess the importance of right ventricular (RV) function at the time of initial presentation on outcome in patients with HLHS, systolic function was determined by qualitative and quantitative methods in 60 consecutive patients before surgical intervention. The effects on stage I operative survival, survival to stage II, and overall survival were analyzed. Initial RV function did not impact on stage I survival. However, analysis of later outcome of the stage I survivors showed that those with prestage I RV dysfunction had significantly greater mortality before stage II. Actuarial survival 18 months after Norwood surgery was 93% for patients with initially normal RV function compared with 47% for those with abnormal function (p = <0.005). The relative risk for later mortality was approximately 11 times greater for patients with initial RV dysfunction. Thus, RV dysfunction identifiable soon after initial presentation does not impact on early survival after Norwood I operation for HLHS. Intermediate and overall survival, however, is significantly decreased in patients with initially diminished RV function.

Modifications to the cavopulmonary anastomosis do not eliminate early sinus node dysfunction

OBJECTIVE

To determine whether operations that theoretically jeopardize the sinus node (hemi-Fontan and/or lateral tunnel Fontan procedures) are associated with a greater risk of sinus node dysfunction than those that theoretically spare the sinus node (bidirectional Glenn and/or extracardiac conduit).

METHODS

Between January 1, 1996, and December 31, 1999, a prospective cohort study was conducted evaluating the incidence of sinus node dysfunction in patients undergoing a bidirectional Glenn or hemi-Fontan procedure and those in whom the Fontan repair was completed with either an extracardiac conduit or a lateral tunnel. Sinus node dysfunction was defined (1) as a heart rate more than 2 SD below age-adjusted norms or (2) as a predominant junctional rhythm and/or a sinus pause of more than 3 seconds as determined by the resting electrocardiogram and/or ambulatory monitoring at hospital discharge.

RESULTS

Fifty-one patients had a bidirectional Glenn shunt (mean age 7.8 +/- 5.1 months) and 79 a hemi-Fontan procedure (mean age 6.9 +/- 2.8 months). The incidence of sinus node dysfunction on postoperative day 1 was significantly higher after the hemi-Fontan (36%) than after the bidirectional Glenn shunt (9.8%); however, by hospital discharge this difference was no longer apparent (hemi-Fontan [8%]; bidirectional Glenn [6%]; P = not significant). No difference in early sinus node dysfunction was discernible after the extracardiac conduit (4/30 [13%]) compared with the lateral tunnel Fontan procedure (6/46 [13%]) (P = not significant). No diagnostic or perioperative variables were predictive of sinus node dysfunction.

CONCLUSIONS

Avoidance of surgery near the sinus node has no discernible effect on the development of early sinus node dysfunction. Thus, concerns about early sinus node dysfunction should not override patient anatomy or surgeon preference as determinants of which cavopulmonary anastomosis to perform.

The hypoplastic left heart syndrome with intact atrial septum: atrial morphology, pulmonary vascular histopathology and outcome

OBJECTIVES

The purpose of this study was to investigate the outcome in infants with hypoplastic left heart syndrome and intact atrial septum and to evaluate the relationship of atrial morphology, left atrial decompression pathway and lung histopathology to outcome.

BACKGROUND

In the hypoplastic left heart syndrome, severe restriction at the atrial level results in marked systemic hypoxemia after birth. Infants with intact atrial septum may be at high risk for mortality after Norwood operation.

METHODS

Of 316 infants with hypoplastic left heart syndrome seen at our center over a 6.5-year period, 18 (5.7%) had intact atrial septum. Medical records and echocardiograms were reviewed.

RESULTS

On echocardiography, three types of intact atrial septal morphology were identified: 1) large left atrium, thick prominent septum secondary with thin septum primary adherent (type A, n = 12); 2) small left atrium with thick, muscular atrial septum (type B, n = 4), and 3) giant left atrium, thin atrial septum with severe mitral regurgitation (type C, n = 2). Seven infants had left atrial decompression pathways that were severely obstructed (3/12 type A, 4/4 type B). Norwood operation was performed in 17 infants; one underwent emergency balloon atrial septostomy and died. Of six early survivors, all with type A atrial morphology and unobstructed decompression pathway, three died after subsequent cavopulmonary surgery. Lung histopathology revealed severely dilated lymphatics and "arterialization" of the pulmonary veins in those with the severest degree of obstruction to left atrial egress (type B atrial morphology).

CONCLUSIONS

Despite aggressive intervention, outcome for infants born with hypoplastic left heart syndrome and intact atrial septum is poor. Maldevelopment of the pulmonary vasculature contributes to the high mortality seen. Atrial morphology can be used as a marker for the severity of pulmonary vascular disease.

[Surgical treatment of hypoplastic left heart syndrome: experience with staged palliative reconstruction]

Hypoplastic left heart syndrome (HLHS) represents an anatomical spectrum of congenital disease with varying degrees of underdevelopment of the left-sided cardiac structures (Figure 1). The outlook for children born with HLHS, an otherwise highly lethal malformation, has improved with increasing experience with reconstructive techniques. This report represents a detailed analysis of the overall risk and mid-term results for a group of 39 consecutive neonates with HLHS referred to our hospital over a 5-year period between January 1994 and November 1998. Twenty-six patients were treated with a Norwood reconstructive procedure (Figure 2). One patient received a cardiac transplant at the request of the parents. Another patient with aortic atresia, ventricular septal defect and normal left ventricle underwent biventricular repair. Eleven patients were not eligible for surgical treatment due to a number of reasons (Table 1). In 26 neonates (9 girls, 17 boys; mean age 9.1 [4 to 42] days) staged reconstruction by Norwood's procedure was performed. The hospital mortality in the first stage of the Norwood procedure was 23% (6/26). Sixteen of the 20 long-term survivors underwent the bidirectional cavopulmonary anastomosis (hemi-Fontan; Figure 3) at a median age of 7.6 (3 to 14) months. All children survived. Up to now, 3 infants received the complete Fontan operation (Figure 4) at 2 years of age. No late death occurred. In 18 out of the 20 survivors neuro-developmental outcome and exercise performance were within the range of normals. Staged surgical palliation represents a realistic therapeutic option for neonates born with HLHS. At this intermediate stage of follow-up exercise performance and quality of life are satisfactory.

Early results of the extracardiac conduit Fontan operation

BACKGROUND

Among the modifications of the Fontan operation, the extracardiac approach may offer the greatest potential for optimizing early postoperative ventricular and pulmonary vascular function, insofar as it can be performed with short periods of normothermic partial cardiopulmonary bypass and without cardioplegic arrest in most cases. In this study, we reviewed our experience with the extracardiac conduit Fontan operation, with a focus on early postoperative outcomes.

METHODS AND RESULTS

Between July 1992 and April 1997, 51 patients (median age 4.9 years) underwent an extracardiac conduit Fontan operation. Median cardiopulmonary bypass time was 92 minutes and has decreased significantly over the course of our experience. Intracardiac procedures were performed in only 5 patients (10%), and the aorta was crossclamped in only 11 (22%). Intraoperative fenestration was performed in 24 patients (47%). There were no early deaths. Fontan failure occurred in 1 patient who was a poor candidate for the Fontan procedure. Transient supraventricular tachyarrhythmias occurred in 5 patients (10%). Median duration of chest tube drainage was 8 days. Factors significantly associated with prolonged resource use (mechanical ventilation, inotropic support, intensive care unit stay, and hospital stay) included longer bypass time and higher Fontan pressure. At a median follow-up of 1.9 years, there was 1 death from bleeding at reoperation.

CONCLUSIONS

The extracardiac conduit Fontan procedure can be performed with minimal mortality and morbidity. Improved results may be related to advantages of the extracardiac approach and improved preservation of ventricular and pulmonary vascular function.

Partial biventricular repair for complex congenital heart defects: an intermediate option for complicated anatomy or functionally borderline right complex heart

BACKGROUND

Partial biventricular repair consists of bidirectional cavopulmonary anastomosis in the presence of separated systemic and pulmonary circulations, with antegrade flow of inferior caval return through an intact or reconstructed pulmonary outflow tract. This versatile procedure may be used as a definitive repair for patients with a functional right heart complex incapable of supporting an entire cardiac output or in patients with complicated anatomy.

METHODS

From July 1992 to April 1997, 23 patients (median age 5.2 years) underwent partial biventricular repair. In 15 of these cases the entire repair, including bidirectional cavopulmonary anastomosis, intracardiac repair, and right ventricular outflow reconstruction, was performed as a planned procedure at our institution. The other eight patients had previously been placed on a Fontan track and had undergone bidirectional cavopulmonary anastomosis; their circulations were converted to a partial biventricular circulation.

RESULTS

There were no early deaths. Complete atrioventricular block developed in two patients with straddling tricuspid valve. At a median follow-up of 17 months, there were no late deaths and three patients had undergone reintervention. Partitioning of the pulmonary arteries to create a classic Glenn anastomosis with antegrade flow to the left lung was performed in one case; another patient underwent an atrial septectomy, and the third patient required revision of tricuspid valve repair. All patients are in New York Heart Association functional class I.

CONCLUSIONS

Partial biventricular repair is a versatile strategy that can be used to manage a variety of forms of complex congenital heart disease. Cases for which the repair is useful include those in which complete biventricular repair is unlikely to be achieved because of limited size or function of the right side of the heart and those in which a patient with a ventricle capable of supporting inferior vena caval return was previously placed on a Fontan track.