Faculty Bibliography

OBJECTIVES: We sought to examine the incidence and possible factors for inducible intra-atrial reentrant tachycardia (IART) in a group of patients after two stages of the Fontan sequence but before the operation. BACKGROUND: Intra-atrial reentrant tachycardia occurs in 10% to 40% of patients after the Fontan operation. No data are available regarding the potential for IART after the first two stages of the Fontan sequence but before the operation. METHODS: The IART induction protocol included programmed extrastimulation and rapid atrial pacing, with and without isoproterenol. RESULTS: The median age of the study group (n = 44, 27 males) was 1.7 years (range 1.2 to 5.2). Forty patients were in sinus rhythm. Twelve patients (27%) had inducible, sustained (>1 min) IART. Three patients (8%) had inducible, nonsustained IART. Bivariate analysis revealed that patients with sustained IART were significantly older at their second operation (median 0.54 vs. 0.40 years, p = 0.05). Multivariate logistic modeling revealed that older age (> or =0.55 years) at the second palliative operation (p = 0.04), older age (> or =1.95 years) at evaluation before the Fontan sequence (p = 0.04) and female gender (p = 0.03) were independently associated with sustained IART. A trend toward a greater frequency of sustained IART was seen in those patients with moderate or severe atrioventricular valve regurgitation (p = 0.07) and in those with resection of the atrial septum (p = 0.06). CONCLUSIONS: The rate of inducible, sustained IART in a group of patients before the Fontan operation is 27% and is associated with older age at the time of second-stage palliation, older age at pre-Fontan evaluation and female gender

Hemodynamics after Norwood palliation for hypoplastic left heart syndrome (HLHS) have been incompletely characterized, although emphasis has been placed on the role that an excess pulmonary-to-systemic blood flow ratio (Qp/Qs) may play in causing hemodynamic instability. Studies suggest that maximal oxygen delivery occurs at a Qp/Qs < 1. However, it remains unclear to what extent cardiac output can increase with increasing pulmonary perfusion. One approach is to use the oxygen excess factor omega, an index of systemic oxygen delivery, and compare omega with measured Qp/Qs. We measured Qp/Qs and omega in neonates after Norwood palliation for HLHS, and determined how they were related. In addition, we determined the temporal course of surrogate indexes of systemic perfusion in the early postoperative period. Arteriovenous oxygen saturation difference, blood lactate, and omega were recorded on admission and every 3 to 12 hours for 2 days in 18 consecutive infants with HLHS or variant after Norwood palliation. Three infants required extracorporeal membrane oxygenation (ECMO) 6 to 9 hours after admission. These infants had higher Qp/Qs, blood lactate, arteriovenous oxygen saturation difference, and lower omega than non-ECMO patients. In non-ECMO patients between admission and 6 hours, omega decreased significantly despite no appreciable change in Qp/Qs. We conclude that: (1) Oxygen delivery is significantly decreased at 6 postoperative hours unrelated to Qp/Qs. This modest decline in oxygen delivery is insufficient to compromise tissue oxygenation. (2) Patients requiring ECMO have significant derangements in oxygen delivery

The surgical management of ventricular septal defects (VSDs) has evolved significantly since the first attempts at closure in the 1950s, now VSDs in virtually any anatomic location are largely closed transatrially with low morbidity. Defects are repaired with one definitive corrective procedure even during infancy. A better understanding of the natural history and hemodynamic sequelae, and improved surgical technique has contributed significantly to these results

Development of a mycotic aneurysm or pseudoaneurysm after subacute bacterial endarteritis is uncommon. Nonetheless, patients with coarctation of the aorta are more likely to develop this complication. We describe a case of a large pseudoaneurysm discovered in a child with a previously undiagnosed aorta coarctation. Successful repair was performed with the aid of partial left heart bypass and the use of an interposition graft. A high index of suspicion is necessary to accurately diagnose this rare but life-threatening entity

OBJECTIVE: To compare neurodevelopmental outcome (NDO) in patients with hypoplastic left heart syndrome (HLHS), other functional single ventricle lesions, and the standard population and to investigate predictors of NDO in the population of children with functional single ventricle (FSV). STUDY DESIGN: A time- and age-defined cohort of patients with the Fontan circulation was recruited to participate in neurodevelopmental testing, behavioral evaluation, and imaging of the central nervous system. The Wechsler Intelligence test was the primary measure of NDO. Analysis included comparison of patients with HLHS with other patients with functional single ventricles. Other potential clinical predictors of NDO were investigated. RESULTS: The mean Full Scale Wechsler Intelligence score was 101.4+/-5.4. For the HLHS subgroup the mean Full Scale Wechsler score was 93.8+/-7.3, and for the non-HLHS subgroup it was 107.0+/-7.0. Although the HLHS group had significantly lower scores than the non-HLHS subgroup, neither subgroup scored significantly different from the standard population on the Wechsler Scales. Socioeconomic status, circulatory arrest, and perioperative seizures also were predictive of neurodevelopmental outcome. CONCLUSION: Neurodevelopmental and behavioral outcome in patients who have undergone the Fontan procedure including patients with HLHS is good in the preschool and early school years, with Wechsler Intelligence scores generally in the normal range

High intensity focused ultrasound (HIFU) is an evolving technology with potential therapeutic applications. Utilizing frequencies of 500 kHz to 10 MHz, HIFU causes localized hyperthermia at predictable depths without injuring intervening tissue. Applications in neurosurgery, urology, oncology and, more recently, cardiology for selective cardiac conduction tissue ablation have been promising. A 'noninvasive' technique for causing localized tissue damage to relieve hemodynamic and life-threatening obstruction in patients with congenital cardiac anomalies could replace more invasive procedures. We, therefore, investigated the ability of HIFU to create lesions in mammalian cardiac tissues ex vivo. Porcine valve leaflet, canine pericardium, human newborn atrial septum, and right atrial appendage were studied. Specimens were mounted and immersed in a water bath at room temperature. Using a 1-MHz phased array transducer, ultrasound energy was applied with an acoustic intensity of 1630 W/cm(2) or 2547 W/cm(2) until a visible defect was created (duration 3 to 25 sec). Macroscopic and microscopic examination demonstrated precise defects ranging from 3 to 4 mm in diameter. No damage was identified to the surrounding tissues. Our study concluded that HIFU can create precise defects in different cardiac tissue without damage to the surrounding tissue. Further investigation is needed to assess potential clinical uses of this technology

OBJECTIVE: To review more than a decade of experience with complete repair of tetralogy of Fallot (TOF) in neonates at the University of Michigan; to assess early and late survival, perioperative complications, and the incidence of reoperation; and to analyze patient, procedural, and morphologic risk factors to determine their effects on outcome. SUMMARY BACKGROUND DATA: Palliation of TOF with systemic-to-pulmonary artery shunts has been the accepted standard for symptomatic neonates and infants. Complete repair has traditionally been reserved for infants older than 6 months of age because of the perception that younger and smaller infants face an unacceptably high surgical risk. RESULTS: A retrospective review from August 1988 to November 1999 consisted of 61 consecutive symptomatic neonates with TOF who underwent complete repair. Thirty-one patients had TOF with pulmonary stenosis, 24 had TOF with pulmonary atresia, and 6 had TOF with nonconfluent pulmonary arteries. The mean age at repair was 16 +/- 13 days, and the mean weight was 3.2 +/- 0.7 kg. Before surgery, 36 patients were receiving an infusion of prostaglandin, 26 were mechanically ventilated, and 11 required inotropic support. Right ventricular outflow tract obstruction was managed with a transannular patch in 49 patients and a right ventricle-to-pulmonary artery conduit in 12. Cardiopulmonary bypass time averaged 71 +/- 26 minutes. Hypothermic circulatory arrest was used in 52 patients (mean 38 +/- 12 minutes). After cardiopulmonary bypass, the average intraoperative right/left ventricular pressure ratio was 55% +/- 13%. There were no new clinically apparent neurologic sequelae after repair. The postoperative intensive care unit stay was 9.1 +/- 8 days, with 6.8 +/- 7 days of mechanical ventilation. There was one hospital death from postoperative necrotizing enterocolitis on postoperative day 71 and four late deaths, only one of which was cardiac-related. Actuarial survival was 93% at 5 years. Follow-up was available for all 60 hospital survivors and averaged 62 months (range 1-141 months). Twenty-two patients required a total of 24 reoperations at an average interval of 26 months after repair. Indications for reoperation included right ventricular outflow tract obstruction (19), branch pulmonary artery stenosis (11), severe pulmonary insufficiency (4), and residual ventricular septal defect (1). The 1-month, 1-year, and 5-year freedom from reoperation rates were 100%, 89%, and 58%, respectively. CONCLUSIONS: Complete repair of TOF in the neonate is associated with excellent intermediate-term survival. Although the reoperation rate is significant, this is to be expected with the complex right ventricular outflow tract and pulmonary artery anatomy seen in symptomatic neonates and the need for conduit replacement in patients with TOF with pulmonary atresia

OBJECTIVES: Neonates with congenital heart disease may appear hemodynamically stable after operation and then suddenly experience catastrophic decompensation. An improved means of predicting which infants will suddenly die in the early postoperative period may lead to lifesaving interventions. Studies indicate that blood lactate level is proportional to tissue oxygen debt, but information linking lactate levels with outcome in infants after operation is limited. We sought to determine whether a change in lactate level over time was predictive of a poor outcome defined as death within the first 72 hours or the need for extracorporeal membrane oxygenation. METHODS: To test this hypothesis, we studied prospectively 46 infants who were less than 1 month old and were undergoing complex cardiac surgical palliation or repair. Postoperative arterial oxygen saturation, bicarbonate, and lactate levels were recorded on admission to the intensive care unit and every 3 to 12 hours for the first 3 days. RESULTS: Thirty-seven patients had a good outcome, and 9 patients had a poor outcome. Mean initial lactate level was significantly greater in patients with a poor outcome (9.4 +/- 3.8 mmol/L) than in patients with a good outcome (5.6 +/- 2.1 mmol/L; P =.03). However, an elevated initial lactate level of more than 6 mmol/L had a low positive predictive value (38%) for poor outcome. In contrast, a change in lactate level of 0.75 mmol/L per hour or more was associated with a poor outcome (P <.0001) and predicted a poor outcome with an 89% sensitivity value, a 100% specificity value, and a 100% positive predictive value. CONCLUSIONS: Serial blood lactate level measurements may be an accurate predictor of death or the requirement for extracorporeal membrane oxygenator support for patients who undergo complex neonatal cardiac surgery

OBJECTIVE: Previous reports have suggested that prematurity and low birth weight are risk factors for definitive surgical intervention in congenital cardiac malformations. The following data review our experience with primary repair of the complex malformation of aortic arch obstruction with ventricular septal defect (VSD) in this patient population. METHODS: Since 1988, 21 consecutive preterm (</=36 weeks) and/or low birth weight (<3000 g) infants with interrupted aortic arch (IAA; n=10), or aortic coarctation (n=11) with VSD, underwent primary arch repair and VSD closure. The mean weight at operation was 2310 g (range, 1200-2900 g), including 12 patients at </=2500 g. The gestational age ranged from 30 to 41 weeks (mean, 36.4 weeks). Five patients with interrupted arch and two patients with coarctation also had severe subaortic stenosis, which was relieved by transatrial incision of the infundibular septum. RESULTS: The overall hospital mortality was 14% (3/21). Death was related to low cardiac output in association with severe subaortic stenosis (n=2) and sepsis (n=1). Late mortality occurred in three patients, two of which were non-cardiac. The mean follow-up was 33 months. Two patients had significant recurrent arch obstruction, which was successfully relieved by balloon angioplasty and surgical correction in one each. The survival at 30 days, and at 1 and 3 years was 86, 76 and 70%, respectively. CONCLUSIONS: Complete primary repair of aortic arch obstruction with VSD can be achieved with good results, even in the preterm and low birth weight infant. Therefore, early surgical repair of this congenital malformation is recommended