William T. Mahle

Risk factors for mortality after the Norwood procedure

OBJECTIVESnRecent studies have suggested that survival following the Norwood procedure is influenced by anatomy and is worse for patients with hypoplastic left heart syndrome (HLHS), particularly aortic atresia (AA), as compared to other forms of functional single ventricle and systemic outflow tract obstruction. The current study was undertaken to evaluate our recent experience with the Norwood procedure and to evaluate potential predictors of operative and 1-year mortality.nnnMETHODSnA retrospective study of risk factors for operative and 1-year mortality in 158 patients undergoing the Norwood procedure between January 1, 1998 and June 30, 2001.nnnRESULTSnHLHS was present in 102 patients (70 with AA) and other forms of functional single ventricle with systemic outflow tract obstruction in the remaining 56. Operative survival was 77% (122/158), 78% for patients with HLHS and 75% for patients with other diagnoses. Multivariable analysis identified birth weight (odds ratio (OR) 0.18/kg, 95% confidence limit (CL) 0.08-0.42, P<0.001), associated cardiac anomalies (OR 4.45, 95% CL 1.50-13.2, P=0.001), total support time (OR 1.02/min, 95% CL 1.01-1.03, P=0.004), and extracorporeal membrane oxygenation (ECMO) or ventricular assist device (VAD) support (OR 17.8, 95% CL 4.40-71.0, P<0.001) as predictors of operative mortality. The anatomic diagnosis (HLHS versus non-HLHS) was not a predictor of mortality, P=0.6). The Kaplan-Meier survival estimate at 1 year was 66% (95% CL 58-73%) and was not different for patients with HLHS compared to non-HLHS, P=0.5. For patients who have survived the Norwood procedure, survival to 1 year was 86% (95% CL 78-91%). Presence of an extra-cardiac anomaly or genetic syndrome (OR 2.70, 95% CL 0.98-7.41%, P=0.05) and presence of an additional cardiac defect (OR 3.99, 95% CL 1.67-9.57, P=0.002) were predictors of worse survival in the first year of life.nnnCONCLUSIONSnThe Norwood procedure is currently being applied to a heterogeneous group of patients. Operative and 1-year survival are equivalent for patients with HLHS and those with other cardiac defects. The presence of additional cardiac or extra-cardiac anomalies are predictors of poor outcome.

Unexpected death after reconstructive surgery for hypoplastic left heart syndrome

BACKGROUNDnAlthough 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.nnnMETHODSnRetrospectively, 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.nnnRESULTSnUnexpected 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).nnnCONCLUSIONSnUnexpected 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.

Impact of early ventricular unloading on exercise performance in preadolescents with single ventricle Fontan physiology.

OBJECTIVESnWe sought to determine if early ventricular volume unloading improves aerobic capacity in patients with single ventricle Fontan physiology.nnnBACKGROUNDnSurgical strategies for patients with single ventricle include intermediate staging or early Fontan completion to reduce the adverse affects of prolonged ventricular volume load. The impact of this strategy on exercise performance has not been evaluated.nnnMETHODSnRetrospectively, we reviewed the exercise stress test results of all preadolescents with single ventricle Fontan physiology. Volume unloading was considered to have occurred at the time of bidirectional cavopulmonary anastomosis or at the time of Fontan surgery in those patients who did not undergo intermediate staging. Potential predictors of aerobic capacity were analyzed using multivariate regression.nnnRESULTSnThe patients (n = 46) achieved a mean percentage predicted of maximal oxygen consumption (VO2max) of 76.1% +/- 21.1%. The mean age at the time of volume unloading was 2.7 +/- 2.4 years, and the mean age at testing was 8.7 +/- 2 years. Intermediate staging was performed in 16 of 46 patients (35%). In multivariate analysis, younger age at volume unloading was associated with increased aerobic capacity (p = 0.003). Other variables were not predictive. The subgroup of patients who underwent volume unloading before two years of age achieved a mean percentage predicted VO2max of 88.6% +/- 24.1%.nnnCONCLUSIONSnPreadolescents with single ventricle who undergo volume unloading surgery at an early age demonstrate superior aerobic capacity compared with those whose surgery is delayed until a later age.

Quantitative echocardiographic assessment of the performance of the functionally single right ventricle after the Fontan operation.

BACKGROUNDnPerformance of the functionally single right ventricle may deteriorate over time. Quantitative assessment of this chamber, however, is complicated by its asymmetric geometry. Automatic detection of borders, and the Doppler-derived index of myocardial performance, are echocardiographic techniques that allow for quantitative assessment regardless of ventricular shape. We sought to evaluate the mechanics of contraction and relaxation in the functionally single right ventricle using these parameters.nnnMETHODSnWe evaluated systemic ventricular function in 35 asymptomatic patients with functionally single right ventricle, having a mean age of 7.8+/-3.1 years, who had undergone the Fontan procedure. We compared them with 32 age-matched normal controls using both automatic detection of borders and Doppler indexes.nnnRESULTSnWhen compared with the controls, the group with a functionally single right ventricle demonstrated diminished systolic function as evidenced by a lower fractional change in area (42.7+/-10.1% vs. 54.6+/-10.5%, p = 0.001), and diminished diastolic function, as demonstrated by a greater reliance on atrial contraction to achieve ventricular filling (32.0+/-4.4% vs. 22.2+/-4.1%, p = 0.001). The mean index of myocardial performance in those with functionally single right ventricles was also greater than in controls (0.41+/-0.12 vs. 0.30+/-0.05, p = 0.001), and the indexed ejection time was shorter (0.35+/-0.05 vs. 0.39+/-0.05, p = 0.01), suggesting less efficient ventricular mechanics.nnnCONCLUSIONSnThese data demonstrate that the systolic and diastolic properties of the functionally single right ventricle differ significantly from those of the normal systemic left ventricle. Use of the echocardiographic techniques provide insight into ventricular mechanics in patients with functionally single ventricles, and may be valuable tools for serial quantitative follow-up.

Atrioventricular valve regurgitation in patients with single ventricle: impact of the bidirectional cavopulmonary anastomosis

BACKGROUNDnIt is not known whether atrioventricular valve regurgitation (AVVR) can improve in some patients after the bidirectional cavopulmonary anastomosis (BCPA) without undertaking concomitant valvuloplasty.nnnMETHODSnWe retrospectively reviewed our experience with patients who underwent the BCPA between June 1989 and June 2000 with specific attention to those patients with moderate or severe AVVR. The degree of AVVR was determined by color Doppler echocardiography. During the study period there were 576 patients who underwent BCPA at a median age of 6.8 months (range, 1.3 months to 4.8 years). The majority of subjects (66%) had a tricuspid valve as the systemic atrioventricular valve. Significant (moderate or severe) AVVR before BCPA was noted in 36 of 576 patients (6%) and was significantly more prevalent (8 of 52 patients, 15%; p = 0.01) in patients with a common atrioventricular canal.nnnRESULTSnOf the 36 subjects with moderate or severe AVVR, 8 had interventions (6 valvuloplasty, 2 aortic arch dilation) at BCPA. There was 1 hospital death (2.8%). Of the remaining 27 survivors who did not undergo additional interventions at BCPA, improvement in AVVR (mild or none) was noted in 6 (22%) at intermediate follow-up (median, 2 years; range, 0.5 to 3.1 years). The presence of significant AVVR before BCPA was not significantly associated with hospital survival or intermediate-term freedom from death or transplantation.nnnCONCLUSIONSnWe conclude that AVVR improves in some patients after BCPA and that valvuloplasty is not justified in all patients with moderate preoperative AVVR.

Exercise performance after the arterial switch operation for d-transposition of the great arteries

Early- and intermediate-term results of the arterial switch operation for D-transposition of the great arteries (D-TGA) are encouraging. However, questions remain about the long-term outcome for these patients, especially with regard to exercise performance. Preliminary studies have demonstrated normal endurance time on treadmills. However, data regarding aerobic capacity and cardiopulmonary function are lacking. We report the cardiopulmonary performance of 22 school-age patients with D-TGA who underwent the arterial switch operation. Outcome variables included maximal oxygen consumption (VO2), maximal cardiac index, and peak heart rate. Patient and procedure-related variables were assessed for their association with outcome variables using linear and logistic regression. The mean values of maximal VO2 (113 +/- 19% predicted) and maximal cardiac index (96 +/- 18% predicted) were within normal limits for the pediatric population. Although the mean peak heart rate for the entire group (184 +/- 14 beats/min) was within normal limits, there were 7 subjects (32%) with chronotropic impairment. Significant ST-segment depression was seen in 2 subjects (9%). In regression analysis, surgery subsequent to the arterial switch was associated with lower maximal cardiac index (p = 0.01). Other variables were not significantly associated with maximal VO2, maximal cardiac index, and peak heart rate. In particular, chronotropic impairment was not significantly associated with maximal VO2 or maximal cardiac index. These findings demonstrate that cardiopulmonary performance during exercise is excellent after the arterial switch operation. The finding of ST-segment depression in some subjects supports the role of formal exercise testing in those patients participating in vigorous athletic activities.

Growth characteristics of the aortic arch after the Norwood operation

OBJECTIVESnWe sought to characterize the growth of the reconstructed aortic arch after the Norwood operation (NO).nnnBACKGROUNDnThe first stage of surgical palliation of hypoplastic left heart syndrome (HLHS), the NO, includes augmentation of the aortic arch with homograft. Growth characteristics of the reconstructed aortic arch, which is comprised of both native aortic tissue and homograft, have not been characterized.nnnMETHODSnRetrospectively, we examined the serial echocardiograms of 50 patients with HLHS who underwent NO to determine the diameter of the reconstructed transverse arch. Measurements were taken immediately after NO and at two other points (1 to 11 years of age). In addition, the autopsy specimens of 10 other patients with HLHS who underwent NO were examined to determine the contribution of native aortic tissue to the overall size of the reconstructed arch at the time of death (12 to 34 months).nnnRESULTSnThe diameter of the transverse aorta increased after NO in all subjects. Its rate of growth paralleled that seen in the normal population, though the reconstructed arch had a significantly larger diameter throughout childhood. Examination of autopsy specimens demonstrated a mean increase in circumference of the native aortic tissue of 0.67 cm (p value <0.01), whereas there was no significant change in homograft circumference.nnnCONCLUSIONSnAfter reconstruction of the aortic arch in HLHS, the diameter of the arch continues to increase throughout childhood, and this increase is due to growth of the native aortic tissue.

Exercise Performance in Tetralogy of Fallot: The Impact of Primary Complete Repair in Infancy

Primary complete repair (PCR) of tetralogy of Fallot (TOF) is now routinely performed in infancy. Although operative results are excellent, the impact on exercise performance is incompletely understood. We reviewed data of all children with TOF who underwent PCR at our institution and had subsequent maximal cycle ergometer exercise testing between January 1995 and December 2000. Of the 193 patients with TOF who underwent PCR, 57 (30%) underwent exercise testing; maximal tests were available for 50 of 57 (88%). Exercise performance of subjects who underwent PCR at <1 YEAR OF AGE WAS COMPARED TO THAT OF THOSE WHO UNDERWENT REPAIR AT >l year of age. The median age at PCR was 10.9 months; 28 subjects (56%) underwent PCR in infancy (<1 year). A transannular incision was employed in the repair in 41 subjects (82%). The mean age at exercise testing was 12.5 ± 3.2 years. The mean maximal VO2 was 94.9 ± 18.8% predicted and the mean maximal work rate was 98.0 ± 20.8% predicted. In multivariate analysis PCR in infancy (age <1 year) was not associated with maximal VO2, peak work rate, peak heart rate, or arrhythmias. Only older age at testing and male gender were significantly associated with higher maximal VO2 (p = 0.005 and p = 0.002, respectively). Intermediate-term exercise performance in subjects who undergo PCR of TOF in early childhood is near normal. Performing PCR in the first year of life does not impact subsequent exercise performance.

Atrioventricular valve replacement in patients with a single ventricle

BACKGROUNDnSignificant atrioventricular valve (AVV) insufficiency has been associated with increased mortality and morbidity in patients with single ventricle. Although many patients can be managed with valvuloplasty alone, some patients require AVV replacement. The optimal timing, outcome, and risk factors for AVV replacement in this population have not been described.nnnMETHODSnWe retrospectively reviewed our experience with AVV replacement in patients with single ventricle from January 1984 to August 2000. Outcome variables included mortality and valve-related complications.nnnRESULTSnSeventeen patients required AVV replacement. Prosthetic valve types included: St. Judes valve in 14, Bjork-Shiley in 1, Hall-Kaster in 1, and Carpentier-Edwards in 1. Valve size ranged from 17 to 33 mm, Median age at valve replacement was 3.0 years (range 7 days to 17.3 years). Of the 16 subjects with normal atrioventricular conduction preoperatively, 7 (44%) developed postoperative complete heart block. Hospital mortality was 29%. Hospital mortality decreased significantly from 56% in 1984 to 1993 to no deaths from 1994 to 2000 (p = 0.03). Younger age (less than 2 years) at operation was also a risk factor for hospital mortality (p = 0.03). There were four late deaths in this series and 1 patient underwent heart transplantation. Of the surviving patients, none has required replacement of the prosthetic valve. No patients have had cerebrovascular accident subsequent to AVV replacement. Functional status is New York Heart Association functional class I in 5, class II in 1, and Class III in 1.nnnCONCLUSIONSnAtrioventricular valve replacement can be performed in patients with single ventricle with acceptable morbidity and mortality. The development of postoperative complete heart block is common. Survival after AVV replacement has improved in recent years, and intervention before patients develop ventricular dysfunction and atrial arrhythmias may further improve outcome.

A dangerous case of colic: anomalous left coronary artery presenting with paroxysms of irritability.

Anomalous left coronary artery originating from the pulmonary artery (ALCAPA) is a rare, but potentially lethal, cause for irritability in infancy. We present the case of a 12-week-old male infant who was managed as a colic patient for several weeks before the diagnosis of ALCAPA was established. A brief review of previous case reports demonstrated that paroxysms of irritability can be a presentation of this disorder. In the majority of cases the manifestations of ALCAPA can be differentiated from other diseases known to cause a infant to be colicky.