Flavian M. Lupinetti

Usefulness of the bidirectional Glenn procedure as staged reconstruction for the functional single ventricle

The bidirectional Glenn operation may be particularly useful as an intermediate procedure before Fontan correction in high-risk patients. From October 1989 through February 1992, 50 patients 1 to 60 months old (median 12) have undergone a bidirectional Glenn operation. Diagnoses included hypoplastic left heart syndrome in 21 patients, pulmonary atresia with intact ventricular septum in 10, tricuspid valve atresia in 9, other complex univentricular heart defects in 9, and Ebsteins anomaly in 1. Mean pulmonary vascular resistance was 2.2 +/- 0.2 Wood U (range 0.5 to 7.3) and mean pulmonary artery area Nakata index was 318 +/- mm2/m2 (range 80 to 821). Additional procedures were performed in 17 patients, including pulmonary artery reconstruction in 15 (29%) and bilateral caval anastomoses in 5 (10%). There were 4 hospital deaths (8%). Two deaths resulted from myocardial infarction in patients with pulmonary atresia with intact ventricular septum and sinusoids and 1 from severe pulmonary vascular disease in a patient with hypoplastic left heart syndrome. There was 1 late death from pneumonia. Actuarial survival is 92 +/- 4% at 1 month and beyond, with a mean follow-up of 13.4 +/- 1 months. Risk factor analysis showed that pulmonary vascular resistance > 3 Wood U and pulmonary artery distortion were associated with increased mortality. Twelve patients have undergone a Fontan procedure at a mean duration after bidirectional Glenn of 18 months with 1 death (8%). The bidirectional Glenn procedure provides excellent palliation in high-risk patients and appears useful as a staging procedure before Fontan correction.

Is Arrhythmia Detection by Automatic External Defibrillator Accurate for Children? Sensitivity and Specificity of an Automatic External Defibrillator Algorithm in 696 Pediatric Arrhythmias

Background—Use of automatic external defibrillators (AEDs) in children aged <8 years is not recommended. The purpose of this study was to develop an ECG database of shockable and nonshockable rhythms from a broad age range of pediatric patients and to test the accuracy of the Agilent Heartstream FR2 Patient Analysis System for sensitivity and specificity. Methods and Results—Children aged ≤12 years who either developed arrhythmias or were at risk for developing arrhythmias were studied. Two sources were used for the database: children whose rhythms were recorded prospectively via a modified AED and children who had arrhythmias captured on paper and digitized for subsequent analysis. The rhythms were divided into 5-second strips, classified by 3 reviewers, and then assessed by the AED analysis algorithm. A total of 696 five-second rhythm strips from 191 children (81 female and 110 male) aged 1 day to 12 years (median 3.0 years) were analyzed. There was 100% specificity for nonshockable rhythms. Sensitivity for ventricular fibrillation was 96%. Conclusions—There was excellent AED rhythm analysis sensitivity and specificity in all age groups for ventricular fibrillation and nonshockable rhythms. The high specificity and sensitivity indicate that there is a very low risk of an inappropriate shock and that the AED correctly identifies shockable rhythms, making the algorithm both safe and effective for children.

Hypothermia preserves function and signaling for mitochondrial biogenesis during subsequent ischemia

Hypothermia is known to protect myocardium during ischemia, but its role in induction of a protective stress response before ischemia has not been evaluated. As cold incites stress responses in other tissues, including heat shock protein induction and signaling mitochondrial biogenesis, we postulated that hypothermia in perfused hearts would produce similar phenomena while reducing injury during subsequent ischemia. Studies were performed in isolated perfused rabbit hearts ( n = 77): a control group (C) and a hypothermic group (H) subjected to decreasing infusate temperature from 37 to 31°C over 20 min. Subsequent ischemia during cardioplegic arrest at 34°C for 120 min was followed by reperfusion. At 15 min of reperfusion, recovery of left ventricular developed pressure (LVDP), maximum first derivative of left ventricular pressure (LV dP/d t max), LV -dP/d t max, and the product of heart rate and LVDP was significantly increased in H ( P < 0.01) compared with C hearts. Ischemic contracture started later in H (97.5 ± 3.6 min) than in C (67.3 ± 3.3 min) hearts. Myocardial ATP preservation and repletion during ischemia and reperfusion were higher in H than in C hearts. mRNA levels of the nuclear-encoded mitochondrial proteins adenine nucleotide translocase isoform 1 (ANT1) and β-F1-adenosinetriphosphatase (β-F1-ATPase) normalized to 28S RNA decreased in C hearts but were preserved in H hearts after reperfusion. Inducible heat shock protein (HSP70-1) mRNA was elevated nearly 4-fold after ischemia in C hearts and 12-fold in H hearts. These data indicate that hypothermia preserves myocardial function and ATP stores during subsequent ischemia and reperfusion. Signaling for mitochondrial biogenesis indexed by ANT1 and β-F1-ATPase mRNA levels is also preserved during a marked increase in HSP70-1 mRNA.

Central pulmonary artery growth patterns after the bidirectional Glenn procedure

The changes in pulmonary artery size and hemodynamics in 30 patients with univentricular cardiac anatomy were examined before and after bidirectional Glenn procedures done between October 1989 and February 1992. Serial angiographic and hemodynamic examinations before and 17.6 +/- 1.6 months after bidirectional Glenn procedures were compared. At the follow-up study there was no significant change in diameter of the pulmonary artery ipsilateral to the bidirectional Glenn shunt, however, a significant decrease was noted in the diameter of the pulmonary artery contralateral to the bidirectional Glenn shunt (p = 0.04). There was also a 32% decrease in the Nakata index of total cross-sectional pulmonary artery area after the bidirectional Glenn procedure (p = 0.004). Total pulmonary blood flow and mean pulmonary artery pressure had decreased, and arterial oxygen saturation had increased at follow-up. These changes, however, did not correlate with the observed changes in pulmonary artery size. By linear regression analysis, a significant relationship was identified between the Nakata index before the bidirectional Glenn procedure and the absolute change in Nakata index (r = 0.83). A significant decrease in Nakata index occurred only in patients with a bidirectional Glenn shunt in place more than 15 months. Sixteen of the 30 patients subsequently underwent total cavo-pulmonary anastomosis with 7 requiring concurrent surgical pulmonary artery reconstruction. Changes in pulmonary artery size observed more than 15 months after the bidirectional Glenn procedure may have implications for subsequent Fontan repair in children with univentricular anatomy.

Risk factors for surgical site infections after pediatric cardiovascular surgery

Background. Although risk factors for surgical site infection (SSI) after cardiovascular (CV) surgery have been well-documented among adults, few studies have been conducted in children. We performed a case-control study to identify risk factors for hospitalized SSI in children undergoing CV surgery. Methods. National Nosocomial Infections Surveillance System criteria were used prospectively to identify cases of hospitalized SSI in patients who underwent CV surgery. Seventy-nine patients who underwent CV surgery without hospitalized SSI were randomly selected as controls. Cases were compared with controls to determine preoperative, intraoperative and postoperative risk factors for hospitalized SSI. Multivariable logistic regression was performed. Results. An SSI developed in 19 of the 826 patients who underwent CV surgery (2.3 cases per 100 surgeries) during the study period. Infection was limited to soft tissue in 12, whereas deeper infection occurred in 7. Causative agents included Staphylococcus aureus (11), coagulase-negative Staphylococcus (5) and Escherichia coli (2). One patient did not have a pathogen isolated. In a multivariable analysis, duration of surgery (odds ratio, 1.4; 95% confidence interval, 1.2 to 1.8) and age <1 month (odds ratio, 14; 95% confidence interval, 3.3 to 58.4) were independently associated with SSI. Conclusions. Age <1 month and longer duration of surgery were independently associated with hospitalized SSI after CV surgery in children.

Optimum treatment of discrete subaortic stenosis

Discrete subaortic stenosis typically appears as a well-defined membrane beneath the aortic valve. To assess the merits of alternative approaches to this problem, we have reviewed the results of operations for discrete subaortic stenosis from 1978 through 1990. Excision of the subaortic membrane alone was performed in 16 patients (group I). Excision of the membrane with resection of septal muscle was performed in 24 patients (group II). The groups were similar in age at operation, duration of follow-up, and preoperative and postoperative transvalvar gradients. There were no operative or late deaths. Reoperations for recurrent subaortic stenosis were performed in 4 group I patients (25%; 70% confidence limits, 16% to 38%) and 1 group II patient (4%; 70% confidence limits, 2% to 11%). Pacemakers were inserted for postoperative complete heart block in 1 group I patient (6%; 70% confidence limits, 2% to 16%) and 2 group II patients (8%; 70% confidence limits, 4% to 16%). We conclude that muscle resection combined with membrane excision in patients with discrete subaortic stenosis does not increase the risk of death or heart block, and does lower the risk of reoperation for recurrent subaortic stenosis.

Echocardiographic assessment of subvalvular aortic stenosis before and after operation

The development of two-dimensional and Doppler echocardiography has provided a noninvasive technique for the diagnosis and serial assessment of patients with subvalvular aortic stenosis. The clinical records and echocardiographic data were reviewed of all patients with subaortic stenosis diagnosed between 1983 and 1991. Of the 77 patients identified (45 male and 32 female), 28 had isolated subaortic stenosis and 49 had associated cardiac lesions. The most frequently encountered associated lesions were ventricular septal defect (n = 19) and coarctation of the aorta/interrupted aortic arch (n = 14). Serial echocardiographic studies, performed in 38 of the 77 patients, documented significant progression of the left ventricular outflow tract gradient in 25 patients (66%) and development of aortic regurgitation in 25 patients (66%). Surgical resection was performed in 36 patients. The preoperative outflow tract peak gradient was 62.9 +/- 31 mm Hg (range 0 to 153), whereas the immediate postoperative gradient was 14.4 +/- 14 mm Hg (range 0 to 67). The two patients with a significant residual gradient (37 and 67 mm Hg, respectively) in the immediate postoperative period had severe subaortic stenosis preoperatively with marked left ventricular hypertrophy and intracavitary gradient. The immediate postoperative echocardiograms demonstrated no worsening of aortic regurgitation in any patient and regression of regurgitation in one patient from mild to none. Intermediate-term follow-up studies were available for review in 13 postoperative patients at a mean of 4 years postoperatively. In 2(15%) of these 13 patients, subaortic stenosis recurred; however, the degree of aortic regurgitation did not increase in any patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Vascular endothelial growth factor and basic fibroblast growth factor in children with cyanotic congenital heart disease

OBJECTIVE Vascular endothelial growth factor and basic fibroblast growth factor are potent stimulators of angiogenesis. Children with cyanotic congenital heart disease often experience the development of widespread formation of collateral blood vessels, which may represent a form of abnormal angiogenesis. We undertook the present study to determine whether children with cyanotic congenital heart disease have elevated serum levels of vascular endothelial growth factor and basic fibroblast growth factor. METHODS Serum was obtained from 22 children with cyanotic congenital heart disease and 19 children with acyanotic heart disease during cardiac catheterization. Samples were taken from the superior vena cava, inferior vena cava, and a systemic artery. Vascular endothelial growth factor and basic fibroblast growth factor levels were measured in the serum from each of these sites by enzyme-linked immunosorbent assay. RESULTS Vascular endothelial growth factor was significantly elevated in the superior vena cava (P =.04) and systemic artery (P =.02) but not in the inferior vena cava (P =.2) of children with cyanotic congenital heart disease compared to children with acyanotic heart disease. The mean vascular endothelial growth factor level, determined by averaging the means of all 3 sites, was also significantly elevated (P =.03). Basic fibroblast growth factor was only significantly elevated in the systemic artery (P =.02). CONCLUSION Children with cyanotic congenital heart disease have elevated systemic levels of vascular endothelial growth factor. These findings suggest that the widespread formation of collateral vessels in these children may be mediated by vascular endothelial growth factor.

Pulmonary function after modified venovenous ultrafiltration in infants: A prospective, randomized trial

OBJECTIVE We sought to examine the effects of modified venovenous ultrafiltration after cardiopulmonary bypass on pulmonary compliance in infants. METHODS We prospectively enrolled 38 infants undergoing their first operation for congenital heart disease. Infants were randomized to receive 20 minutes of modified ultrafiltration after bypass or control. Static and dynamic compliance was measured after induction of anesthesia, before and immediately after filtration in the operating theater, 1 hour after return to the pediatric intensive care unit, and 24 hours after the operation. Length of time on the ventilator, inotropic requirements, and length of stay in the intensive care unit were recorded. RESULTS Modified ultrafiltration produced a significant immediate improvement in dynamic (pre-ultrafiltration 2.5 +/- 1.9 mL/cm H(2)O to post-ultrafiltration 2.9 +/- 2.7 mL/cm H(2)O, P =.03) and static (pre-ultrafiltration 2.1 +/- 0.9 mL/cm H(2)O to post-ultrafiltration 2.9 +/- 2.1 mL/cm H(2)O, P =.04) compliance. However, there was no significant difference in the change in dynamic (P =.3) or static (P =.7) compliance in the ultrafiltration and control groups when compared before the operation, after the operation, and at 24 hours. There was no significant difference in the time to extubation between patients and control subjects (140 +/- 91 hours vs 90 +/- 58 hours) or the length of intensive care unit stay (10.0 +/- 9.1 days vs 7.4 +/- 5.7 days). CONCLUSIONS Modified ultrafiltration produces an improvement in pulmonary compliance after bypass in infants. However, these improvements are not sustained past the immediate post-ultrafiltration period and do not lead to a decreased length of intubation or intensive care unit stay.

Stent redilation in canine models of congenital heart disease: Pulmonary artery stenosis and coarctation of the aorta

In a canine puppy model, pulmonary artery stenosis was created by banding the left pulmonary artery to 30-40% of its original diameter. Animals underwent right heart catheterization and angiography 1-2 mo later, and Palmaz P308 stents were implanted. Stent redilation was performed 3-5 mo later. One mo postredilation, the animals were restudied and sacrificed. Coarctations of the aorta were created by transverse aortic incision and longitudinal repair. P308 stent implantation was performed 2-3 mo later. Stent redilation was performed after 6-10 mo, and the animals were restudied and sacrificed 1-2 mo later. Stent implantation was performed in 6 puppies with pulmonary artery stenosis, as 2 animals developed postoperative pulmonary arterial hypoplasia, precluding stenting. The stenosis diameter increased from 4.8 +/- 0.5 mm to 7.4 +/- 0.6 mm (mean +/- SE) following stenting (P = 0.005), and increased further to 9.2 +/- 0.7 mm following redilation (P < 0.001). There were no significant vessel tears or ruptures. Coarctation stenting was performed in 8 animals. The coarctation was dilated from 5.8 +/- 0.9 mm to 9.8 +/- 0.6 mm (P < 0.001), and to 13.5 +/- 0.5 mm at redilation (P = 0.002). Redilation could not be performed in 1 animal. Aortic rupture and death occurred in 2 of 7 animals at redilation. Stent implantation and redilation in experimental pulmonary artery stenosis appears safe and effective. Though stent implantation for coarctation of the aorta appears safe, there was a 28% aortic rupture rate at stent redilation in this model.