Pulmonary arterial hypertension in patients with prior atrial switch procedure for d-transposition of great arteries (dTGA).

UNLABELLED: Pulmonary arterial hypertension (PAH) is an uncommon complication of atrial switch repair (Mustard or Senning) for d-transposition of the great arteries (dTGA), often difficult to diagnose by trans-thoracic echocardiography. This patient population is unique in that heart failure and elevated filling pressures are common after atrial switch repairs. Most studies evaluating the use of PAH therapies have excluded this group of patients. METHODS: Our echocardiography database was reviewed for patients with a diagnosis of dTGA status post-atrial switch operation treated with pulmonary vasodilator therapy (monotherapy or combination). RESULTS: Six patients (2 male, 4 female) were identified from 104 patients (67% male). Mean age at atrial switch was 22.1 months; mean age of PAH diagnosis was 29.3 years. Functional class improved from a baseline mean of 3.3 to 1.8 on treatment (p=0.001). No adverse events were associated with treatment. 3 of 4 patients initially referred for heart-lung transplant no longer require transplantation. CONCLUSIONS: PAH is a late complication of the atrial switch procedure for dTGA, affecting 5.7% of our dTGA atrial switch population, with a higher incidence in female patients. In this cohort, pulmonary arterial vasodilator therapy was well tolerated and improved functional status.

Pre-hospital discharge car safety seat testing in infants following congenital heart surgery.

The purpose of this study was to expand the American Academy of Pediatrics' (AAP) car safety seat testing recommendation to include high-risk infants following cardiac surgery. Car safety seat testing (< or =4 days prior to discharge) was retrospectively reviewed for 66 postoperative infants. Car safety seat testing was performed according to AAP guidelines. Failure of the test was defined as the occurrence of apnea, bradycardia, or oxygen desaturation. Average birth weight was 3.1 +/- 0.5 kg. Two patients were born <37 weeks of gestation. Surgical procedures included modified Blalock-Taussig shunt (15), arterial switch operation (12), Norwood-Sano modification (11), coarctation repair (8), repair of tetralogy of Fallot (6), repair of truncus arteriosus (4), repair of total anomalous pulmonary venous return (3), pacemaker (2), repair of interrupted aortic arch and ventricular septal defect (VSD) (1), repair of coarctation/VSD (1), orthotopic heart transplant (1), repair of VSD (1), and patent ductus arteriosus ligation (1). Average age at discharge was 28 +/- 21 days. Four patients (6%) failed car safety seat testing secondary to a decrease in oxygen saturation. One of four passed on retesting after parental education; three of 4 (75%) were discharged home in a supine car safety seat. There was no relationship between the type of surgery and car safety seat test failure. It may be beneficial to extend the AAP recommendations for car safety seat testing to include this high-risk patient population.

Right pulmonary agenesis converts an incomplete vascular ring into a near-complete vascular ring.

A unique combination of pulmonary agenesis and anatomic left aortic arch with aberrant right subclavian artery was identified in two patients. Because of the right pulmonary agenesis, there is rotation of mediastinal contents, especially the aortic arch, into the right chest, converting an incomplete vascular ring to a near-complete vascular ring. The anterior portion of the ring is formed by the ascending aorta and aortic arch, whereas the posterior portion is formed by the aberrant right subclavian artery. Subclavian artery reimplantation and aortopexy effectively relieve the anterior and posterior tracheoesophageal compressive forces.

Closure of symptomatic ventricular septal defects: how early is too early?

With improvements in technology and surgical technique, pediatric cardiologists are challenging surgeons to close symptomatic ventricular septal defects (VSDs) in ever smaller patients. Although delaying surgery may facilitate operative repair, early intervention decreases the period of time these patients require therapy to prevent heart failure, maintains growth, and minimizes exposure to increased pulmonary pressures. To evaluate early intervention, we compare the outcomes of VSD closure in different-sized children. From December 2002 to July 2005, 225 patients underwent closure of a VSD. These patients were divided into four weight-based groups: <4 kg (group 1, n = 28), 4 to 6 kg (group 2, n = 93), 6 to 10 kg (group 3, n = 47), and >10 kg (group 4, n = 57). We reviewed operative and postoperative data, and comparisons were made between the groups. Median weights and ages at the time of surgery were 3.5 kg and 77 days (group 1), 4.9 kg and 128 days (group 2), 7.1 kg and 309 days (group 3), and 18.2 kg and 190 days (group 4). Operative data included cardiopulmonary bypass (CPB), aortic cross-clamp, and procedure times. CPB (p = 0.064), cross-clamp (p = 0.665), and procedure (p = 0.187) times were not significantly affected by decreasing weight. Postoperative continuous data included duration of ventilation and length of intensive care unit (ICU) and hospital stay. Ventilation (p = 0.667) and ICU (p = 0.976) times and length of hospital stay (p = 0.905) were also unaffected by decreasing weight. Postoperative catagoric data included complications and presence of a residual VSD. There was no significant difference in complications (p = 0.763) or residual VSD (p = 0.696) between groups. There was no mortality and no persistent heart block requiring placement of a permanent pacemaker. With improvements in technology and surgical technique, safe and effective VSD closure can be performed in increasingly smaller children. Earlier repair decreases the period of time these patients require aggressive medical therapy to prevent heart failure and maintain growth. It also decreases the period of time for which they are exposed to increased pulmonary pressures and are at risk for infectious respiratory complications. It does not appear to affect operative or postoperative outcomes.

Prehospital discharge car safety seat testing of infants after congenital heart surgery.

BACKGROUND: This study aimed to expand the American Academy of Pediatrics (AAP) car safety seat testing recommendation to include high-risk infants after cardiac surgery. METHODS: Car safety seat testing (< or =4 days before discharge), performed according to AAP guidelines, was retrospectively reviewed for 66 postoperative infants. Failure was defined as apnea, bradycardia, or oxygen desaturation. RESULTS: The average birth weight of the study infants was 3.1 +/- 0.5 kg. Two patients were born at less than 37 weeks gestation. Surgical procedures included modified Blalock-Taussig shunt technique (n = 15), arterial switch operation (n = 12), Norwood Sano modification (n = 11), coarctation repair (n = 8), repair of tetralogy of Fallot (n = 6), repair of truncus arteriosus (n = 4), repair of total anomalous pulmonary venous return (n = 3), pacemaker placement (n = 2), repair of interrupted aortic arch and ventriculoseptal defect (VSD) (n = 1), repair of coarctation and VSD (n = 1), orthotopic heart transplant (n = 1), repair of VSD (n = 1), and patent ductus arteriosus ligation (n = 1). The average age at discharge was 28 +/- 21 days. Four patients (6%) failed car safety seat testing because of a fall in oxygen saturation. One of the four patients passed on retesting after parental education, whereas three of the four (75%) were discharged home in a supine car safety seat. There was no relationship between the type of surgery and car safety seat test failure. CONCLUSION: It may be beneficial to extend the AAP recommendations for car safety seat testing to include high-risk infants after cardiac surgery.

Gastric tonometry and direct intraabdominal pressure monitoring in abdominal compartment syndrome.

BACKGROUND/PURPOSE: Abdominal compartment syndrome (ACS) may complicate abdominal closure in patients with abdominal wall defects, abdominal trauma, intraperitoneal bleeding, and infection. Increased intraabdominal pressure (IAP) leads to respiratory compromise, organ hypoperfusion, and a high mortality rate. This study evaluates the efficacy of continuous direct monitoring of IAP and gastric tissue pH in detecting impending ACS. METHODS: Ten mongrel puppies weighing 2.8 to 6.4 kg underwent general endotracheal anesthesia, placement of an intraabdominal inflatable balloon to simulate ACS and a Swan-Ganz catheter to measure direct IAP. A gastric tonometer, nasogastric tube, foley catheter, and arterial catheter also were inserted. Half-hourly inflation's of the intraabdominal balloon were used to simulate the development of ACS. Direct intraabdominal (IAP), gastric (GP), bladder (BP), and peak airway pressures (PAP) were measured. Gastric tonometry fluid and arterial blood gas levels were obtained during inflation, and the gastric tissue pH level was calculated. Data were statistically analyzed using Pearson's correlation coefficients. RESULTS: Baseline pressures were 2 to 5 cm H(2)O in the stomach and bladder catheters, 1 to 3 mm Hg in the intraabdominal catheter, and correlated with a gastric tissue pH level of 7.4. Significantly high correlation coefficients (cc) were observed between IAP versus BP (cc, 0.77; P <.002). IAP versus GP (cc, 0.79; P <.002) and IAP versus PAP (c, 0.83; P <.0004). A high negative correlation coefficient was noted between gastric pH and IAP (cc, 0.61; P <.026). The pH level dropped to 7.0 with BP and GP of 20 cm H(2)O and IAP of 10 mm Hg, to 6.8 at 30 cm H(2)O and 20 mm Hg, and 6.5 at 40 cm H(2)O and 30 mm Hg, respectively. However, correlation coefficients between gastric tissue pH and BP, GP, or PAP were not significant. CONCLUSIONS: These data suggest that continuous direct intraabdominal pressure monitoring is a simple and effective method that correlates well with indirect bladder or gastric pressure measurement. Changes in gastric tissue pH in association with increased intraabdominal pressure may be an early indicator of impending abdominal compartment syndrome. These observations indicate that these techniques may be more sensitive than current methods of indirect measurement, which may be associated with delayed recognition of ACS.

Leptin production in adipocytes from morbidly obese subjects: stimulation by dexamethasone, inhibition with troglitazone, and influence of gender.

This study examined the regulation of leptin production by dexamethasone and troglitazone. Subcutaneous and omental adipose tissue was obtained during bariatric surgical procedures (30 women and 16 men; body mass index, 52.5 +/- 1.7 kg/m2, age, 39 +/- 2 yr), and adipocytes were cultured in suspension. Subcutaneous adipocytes from females released significantly more leptin than did omental cells from the same subject (P < 0.05), but basal leptin release was not different in adipocytes from these depots in males. Dexamethasone (0.1 micromol/L) significantly increased leptin release within 24 h from sc (135 +/- 13% of control) and omental (227 +/- 53%) adipocytes of females, but not males. Dexamethasone-stimulated leptin production at 48 h was significantly greater in the omental adipocytes of females (398 +/- 64% of control) than in sc adipocytes of females (207 +/- 21%) or the omental (211 +/- 33%) and sc (180 +/- 23%) adipocytes of males. Troglitazone (10 micromol/L; 48 h) significantly inhibited dexamethasone-stimulated leptin release in sc (57 +/- 10.7% inhibition) and omental adipocytes (134 +/- 26% inhibition). There was no gender-related difference in the effect of troglitazone to inhibit dexamethasone-stimulated leptin release. Troglitazone significantly inhibited basal leptin production from omental adipocytes by 15.0 +/- 5.2%. The effect of dexamethasone and troglitazone to regulate leptin release was mediated through changes in ob gene expression, but did not involve changes in glucose uptake or metabolism to lactate. The data suggest that adipocytes from females are more responsive to the stimulatory effect of dexamethasone in vitro than are adipocytes from males. If adipocytes from females are more responsive to relevant in vivo stimuli for leptin secretion such as insulin or glucose, this could contribute to the gender difference in serum leptin. The data also suggest that leptin release from omental adipocytes may be more responsive to hormonal and nutrient regulation in vivo than are sc adipocytes.

Evaluation of small intestine submucosa and acellular dermis as diaphragmatic prostheses.

BACKGROUND/PURPOSE: The repair of large congenital diaphragmatic defects in the neonate continues to be a challenge. Polytetrafluoroethylene (PTFE) is the synthetic material most widely used for reconstruction in instances of partial and complete diaphragmatic agenesis. Recurrent hernia is a frequent complication, because this material does not grow with the infant. This study evaluates two novel materials; small intestine submucosa (SIS; Cook Biotech, Lafayette, IN), and acellular dermis (AlloDerm; Lifecell Corp, The Woodland, TX) for diaphragm reconstruction in growing animals. METHODS: Sprague-Dawley rats (100 g, n = 87) were anesthetized and underwent laparotomy. The control group (n = 18) underwent a sham laparotomy with a left subcostal incision and closure. The other two groups underwent central excision of the left hemidiaphragm (50% loss) and reconstruction with either a SIS (n = 35) or AlloDerm (n = 19) patch sutured circumferentially with 6-0 prolene. Seventy-two animals survived the operation, and were killed at five separate time intervals (2 weeks, 1, 2, 3, and 4 months). Chest radiographs were performed monthly and before death. Radiographs were reviewed in a blinded fashion by two observers as were the necropsies, and rib deformity was noted if present. Histological examination of the diaphragm patch was performed in each animal. RESULTS: There was no evidence of rib deformity noted on gross examination at necropsy or on chest radiograph in either experimental group. At necropsy, all patches were intact without hernia, eventration, or contraction. Histology findings initially showed acute and chronic inflammatory changes in both patch materials that lessened at the 2-month time interval. Both prosthetic patches began to thin at 3 months and was most prominent in the SIS rats. At 4 months, both SIS and AlloDerm remained viable without evidence of necrosis. Each patch showed evidence of fibroblastic incorporation and small capillary ingrowth. These changes were more prominent in the AlloDerm group. There was no evidence of skeletal muscle ingrowth. CONCLUSIONS: These data indicate SIS and AlloDerm may be useful materials for prosthetic repair in instances of partial or total agenesis of the diaphragm. Further investigation in a large animal model over a longer duration is indicated.