Twenty-year experience with heart transplantation for infants and children with restrictive cardiomyopathy: 1986-2006.

Idiopathic restrictive cardiomyopathy (RCM) is a rare cardiomyopathy in children notable for severe diastolic dysfunction and progressive elevation of pulmonary vascular resistance (PVR). Traditionally, those with pulmonary vascular resistance indices (PVRI) >6 W.U. x m(2) have been precluded from heart transplantation (HTX). The clinical course of all patients transplanted for RCM between 1986 and 2006 were reviewed. Preoperative, intraoperative and postoperative variables were evaluated. A total of 23 patients underwent HTX for RCM, with a mean age of 8.8 +/- 5.6 years and a mean time from listing to HTX of 43 +/- 60 days. Preoperative and postoperative (114 +/- 40 days) PVRI were 5.9 +/- 4.4 and 2.9 +/- 1.5 W.U. x m(2), respectively. At time of most recent follow-up (mean = 5.7 +/- 4.6 years), the mean PVRI was 2.0 +/- 1.0 W.U. x m(2). Increasing preoperative mean pulmonary artery pressure (PA) pressure (p = 0.04) and PVRI > 6 W.U. x m(2) (chi(2)= 7.4, p < 0.01) were associated with the requirement of ECMO postoperatively. Neither PVRI nor mean PA pressure was associated with posttransplant mortality; 30-day and 1-year actuarial survivals were 96% and 86%, respectively. Five of the seven patients with preoperative PVRI > 6 W.U. x m(2) survived the first postoperative year. We report excellent survival for patients undergoing HTX for RCM despite the high proportion of high-risk patients.

Bidirectional cavopulmonary anastomosis: impact on diastolic ventricular function indices.

Systolic ventricular function has been demonstrated to remain unchanged following bidirectional cavopulmonary anastomosis (BCPA). The effects of BCPA on diastolic ventricular performance have not been critically assessed. The objective of this study was to evaluate the changes in diastolic ventricular function indices early after BCPA. Nineteen patients were enrolled prospectively. Transthoracic echocardiograms were performed at a median of 4 days prior to and 5 days subsequent to BCPA. Diastolic and systolic echocardiographic indices of ventricular performance were measured for the dominant ventricle. End diastolic volume decreased postoperatively (71.1 +/- 21.1 vs 68.08 +/- 17.9 ml/m2, p = 0.05). Tei index increased postoperatively (0.51 +/- 0.2 vs 0.62 +/- 0.1, p = 0.002), whereas inflow Doppler E velocity (70.3 +/- 13 vs 56.3 +/- 24.7 cm/sec, p = 0.04), E/A ratio (1.18 +/- 0.52 vs 0.84 +/- 0.2, p = 0.02), tissue Doppler E' velocity (9.5 +/- 2.5 vs 6.4 +/- 3.2 cm/sec, p = 0.03) and diastolic flow propagation velocity (56.5 +/- 12 vs 52.8 +/- 11 cm/sec, p = 0.04) all decreased. There was no change in ventricular mass, area change fraction, heart rate, or inflow Doppler A or tissue Doppler A' and S' velocities. This study demonstrated that diastolic indices of ventricular performance are altered indicating decreased diastolic function early following BCPA. Whether this observation is a result of a change in ventricular mass:volume ratio, loading conditions of the ventricle, ventricular geometry, or the effects of cardiopulmonary bypass remains to be determined.

Postoperative hemodynamics after Norwood palliation for hypoplastic left heart syndrome.

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.

Inducibility of intra-atrial reentrant tachycardia after the first two stages of the Fontan sequence.

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.

Neurodevelopmental outcome of patients after the fontan operation: A comparison between children with hypoplastic left heart syndrome and other functional single ventricle lesions.

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 effect on cardiac tissues: potential for clinical application.

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.

Complete repair of tetralogy of Fallot in the neonate: results in the modern era.

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.

Serial blood lactate measurements predict early outcome after neonatal repair or palliation for complex congenital heart disease.

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.