Carl L. Backer

Coronary Artery Fistulas in Infants and Children: A Surgical Review and Discussion of Coil Embolization

BACKGROUND Coronary artery fistula (CAF) is a rare congenital anomaly that can be complicated by intracardiac shunts, endocarditis, myocardial infarction, or coronary aneurysms. Recent reports have emphasized the efficacy of percutaneous transcatheter techniques. The purpose of this article is to review a 28-year surgical experience with CAF as a standard for comparison and to discuss the emergence and efficacy of transcutaneous catheter coil embolization as an alternative form of therapy. METHODS From 1968 to 1996, 17 patients (age, 6 weeks to 16.5 years; mean age, 5.5 years) were diagnosed with CAF: 8 of 12 by echocardiography and 17 of 17 by cardiac catheterization. All patients with isolated CAF (n = 13) were asymptomatic despite significant clinical, electrocardiographic, and chest roentgenographic findings in 10. Sixteen had congenital CAF and 1 had acquired CAF after tetralogy of Fallot repair with injury of the anomalous left anterior descending coronary artery. Associated anomalies included tetralogy of Fallot (2), atrial septal defect (1), and patent ductus arteriosus (1). Nine fistulas originated from the right coronary artery and eight from the left. Drainage was to the right ventricle (9), right atrium (4), pulmonary artery (3), and left atrium (1). RESULTS All patients had a median sternotomy with epicardial or endocardial ligation. Cardiopulmonary bypass was used in 8; 1 of these (iatrogenic CAF) required distal internal mammary artery bypass graft. There were no operative or late deaths. Follow-up evaluation by physical examination (17), echocardiography (8), and catheterization (2) showed no evidence of recurrent or residual CAF. A retrospective review of the 16 available cine cardioangiograms showed that coil embolization was possible in, at most, 6 patients. CONCLUSIONS Early surgical management of CAF is a safe and effective treatment resulting in 100% survival and 100% closure rate. Transcatheter embolization is a reasonable alternative to standard surgical closure in only a very small, select group of patients. These surgical results should be considered the standard against which transcatheter techniques are compared.

Anomalous origin of the left coronary artery from the pulmonary artery: collective review of surgical therapy

Anomalous origin of the left coronary artery from the pulmonary artery is an extremely rare but potentially fatal congenital coronary anomaly. Prompt surgical reestablishment of a two-coronary system on diagnosis yields excellent results and allows progressive and nearly total myocardial recovery. Follow-up of all patients is required to assess the adequacy of repair and to exclude ongoing or recurrent myocardial insult.

Dexamethasone reduces the inflammatory response to cardiopulmonary bypass in children

BACKGROUND A randomized, prospective, double-blind study of 29 children was performed to evaluate the hypothesis that dexamethasone administration prior to cardiopulmonary bypass would decrease the inflammatory mediator release and improve the postoperative clinical course. METHODS Fifteen children received dexamethasone (1 mg/kg intravenously) and 14 (controls) received saline solution 1 hour prior to CPB. Serial blood analyses for interleukin-6, tumor necrosis factor-alpha, complement component C3a, and absolute neutrophil count were performed. Postoperative variables evaluated included temperature, supplemental fluids, alveolar-arterial oxygen gradient, and days of mechanical ventilation. RESULTS Dexamethasone caused an eightfold decrease in interleukin-6 levels and a greater than threefold decrease in tumor necrosis factor-alpha levels after CPB (p < 0.05). Complement component C3a and absolute neutrophil count were not affected by dexamethasone. The mean rectal temperature for the first 24 hours postoperatively was significantly lower in the group given dexamethasone than in the controls (37.2 degrees +/- 0.4 degrees C versus 37.7 degrees +/- 4 degrees C; p = 0.007). Dexamethasone-treated patients required less supplemental fluid during the first 48 hours (22 +/- 28 mL/kg versus 47 +/- 34 mL/kg; p = 0.04). Compared with controls, dexamethasone-treated children had significantly lower alveolar-arterial oxygen gradients during the first 24 hours (144 +/- 108 mm Hg versus 214 +/- 118 mm Hg; p = 0.02) and required less mechanical ventilation (median duration, 3 days versus 5 days; p = 0.02). CONCLUSIONS Dexamethasone administration prior to CPB in children leads to a reduction in the postbypass inflammatory response as assessed by cytokine levels and clinical course.

Characterization of Inwardly Rectifying K+ Channel in Human Cardiac Myocytes Alterations in Channel Behavior in Myocytes Isolated From Patients With Idiopathic Dilated Cardiomyopathy

BACKGROUND Little is known about the characteristics of the inwardly rectifying K+ channel (IK1) and the influence of preexisting heart disease on the channel properties in the human heart. METHODS AND RESULTS We studied the characteristics of cardiac IK1 in freshly isolated adult human atrial and ventricular myocytes by using the patch-clamp technique. Specimens were obtained from the atria and ventricles of 48 patients undergoing cardiac surgery or transplantation and from four explanted donor hearts. The action potential in ventricular myocytes exhibited a longer duration (391.4 +/- 30.2 milliseconds at 90% repolarization, n = 10) than in atrium (289.4 +/- 23.0 milliseconds, n = 18, P < .001) and had a fast late repolarization phase (phase 3). The final phase of repolarization in ventricle was frequency independent. Whole-cell IK1 in ventricle exhibited greater slope conductance (84.0 +/- 7.9 nS at the reversal potential, EK; n = 27) than in atrium (9.7 +/- 1.2 nS at EK; n = 8, P < .001). The steady-state current-voltage (I-V) relation in ventricular IK1 demonstrated inward rectification with a region of negative slope. This negative slope region was not prominent in atrial IK1. The macroscopic currents were blocked by Ba2+ and Cs+. The channel characteristics in ventricular myocytes from patients with congestive heart failure after idiopathic dilated cardiomyopathy (DCM) exhibited distinct properties compared with those from patients with ischemic cardiomyopathy (ICM). The action potential in ventricular myocytes from patients with DCM had a longer duration (490.8 +/- 24.5 milliseconds, n = 11) compared with that for ICM (420.6 +/- 29.6 milliseconds, n = 11, P < .01) and had a slow repolarization phase (phase 3) with a low resting membrane potential. The whole-cell current slope conductance for DCM was smaller (41.2 +/- 9.0 nS at EK, n = 7) than that for ICM (80.7 +/- 17.0 nS, n = 6, P < .05). In single-channel recordings from cell-attached patches, ventricular IK1 channels had characteristics similar to those of atrial IK1; channel openings occurred in long-lasting bursts with similar conductance and gating kinetics. In contrast, the percent of patches in which IK1 channels were found was 34.7% (25 of 72) of patches in atrium and 88.6% (31 of 35) of patches in ventricle. Single IK1 channel activity for DCM exhibited frequent long-lasting bursts separated by brief interburst intervals at every holding voltage with the open probability displaying little voltage sensitivity (approximately 0.6). Channel activity was observed in 56.2% (18 of 32) of patches for DCM and 77.4% (24 of 31) of patches for ICM. Similar results were obtained from atrial IK1 channels for DCM. In addition, channel characteristics were not significantly different between ICM and explanted donor hearts (donors). IK1 channels in cat and guinea pig had characteristics virtually similar to those of humans, with the exception of lower open probability than that in humans. CONCLUSIONS These results suggest that the electrophysiological characteristics of human atrial and ventricular IK1 channels were similar to those of other mammalian hearts, with the possible exception that the channel open probability in humans may be higher, that the whole-cell IK1 density is higher in human ventricle than in atrium, and that IK1 channels in patients with DCM exhibited electrophysiological properties distinct from IK1 channels found in patients with ICM and in donors.

Fontan Conversion To Cavopulmonary Connection And Arrhythmia Circuit Cryoablation

OBJECTIVES We review our surgical experience patients with atriopulmonary Fontan operations who had obstructive or arrhythmia indications for conversion to total cavopulmonary artery connections, arrhythmia circuit cryoablation, and placement of atrial antitachycardia pacemaker. METHODS Fourteen patients (mean age 14 +/- 4 years) had conversion to total cavopulmonary artery connection 8 +/- 3 years after the original atriopulmonary Fontan operation primarily for atrial arrhythmias in 11, obstructive lesions in 2, and bradycardia with cyanosis in 1. Arrhythmia circuit cryoablation was performed on 11 patients and 10 had atrial antitachycardia pacemakers. Preoperative functional New York Heart Association class was IV in 9, III in 4, and II in 1. RESULTS One patient had brain death (7%) presumably caused by resternotomy complications despite an excellent hemodynamic result. Another required reoperation for a maldeployed clamshell device after attempted fenestration closure. Average length of stay was 10 +/- 3 days; chest tubes were removed on day 7 +/- 3. There were no long-term deaths (mean follow-up 1.7 years, range 5 months to 5 years). Postoperative arrhythmias occurred in five patients, three of whom had successful termination by antitachycardia pacemaker and two who had pharmacologic control of their respective junctional ectopic and slow atrial tachycardia. All patients have improved to New York Heart Association class I or II. CONCLUSIONS Total cavopulmonary artery conversion in association with arrhythmia circuit cryoablation and atrial antitachycardia pacemaker placement can be accomplished with low morbidity and mortality, oftentimes resulting in dramatic increases in functional class and control of life-threatening arrhythmias.

Characterization and Functionality of Cardiac Progenitor Cells in Congenital Heart Patients

Background— Human cardiac progenitor cells (hCPCs) may promote myocardial regeneration in adult ischemic myocardium. The regenerative capacity of hCPCs in young patients with nonischemic congenital heart defects for potential use in congenital heart defect repair warrants exploration. Methods and Results— Human right atrial specimens were obtained during routine congenital cardiac surgery across 3 groups: neonates (age, <30 days), infants (age, 1 month to 2 years), and children (age, >2 to ≤13 years). C-kit+ hCPCs were 3-fold higher in neonates than in children >2 years of age. hCPC proliferation was greatest during the neonatal period as evidenced by c-kit+ Ki67+ expression but decreased with age. hCPC differentiation capacity was also greatest in neonatal right atrium as evidenced by c-kit+, NKX2–5+, NOTCH1+, and NUMB+ expression. Despite the age-dependent decline in resident hCPCs, we isolated and expanded right atrium–derived CPCs from all patients (n=103) across all ages and diagnoses using the cardiosphere method. Intact cardiospheres contained a mix of heart-derived cell subpopulations that included cardiac progenitor cells expressing c-kit+, Islet-1, and supporting cells. The number of c-kit+–expressing cells was highest in human cardiosphere-derived cells (hCDCs) grown from neonatal and infant right atrium. Furthermore, hCDCs could differentiate into diverse cardiovascular lineages by in vitro differentiation assays. Transplanted hCDCs promoted greater myocardial regeneration and functional improvement in infarcted myocardium than transplanted cardiac fibroblasts. Conclusions— Resident hCPCs are most abundant in the neonatal period and rapidly decrease over time. hCDCs can be reproducibly isolated and expanded from young human myocardial samples regardless of age or diagnosis. hCPCs are functional and have potential in congenital cardiac repair.

Revision of previous Fontan connections to total extracardiac cavopulmonary anastomosis: A multicenter experience.

BACKGROUND Conversion to total extracardiac cavopulmonary anastomosis is an option for managing patients with dysfunction of a prior Fontan connection. METHODS Thirty-one patients (19.9 +/- 8.8 years) underwent revision of a previous Fontan connection to total extracardiac cavopulmonary anastomosis at four institutions. Complications of the previous Fontan connection included atrial tachyarrhythmias (n = 20), progressive heart failure (n = 17), Fontan pathway obstruction (n = 10), effusions (n = 10), pulmonary venous obstruction by an enlarged right atrium (n = 6), protein-losing enteropathy (n = 3), right atrial thrombus (n = 2), subaortic stenosis (n = 1), atrioventricular valve regurgitation (n = 3), and Fontan baffle leak (n = 5). Conversion to an extracardiac cavopulmonary connection was performed with a nonvalved conduit from the inferior vena cava to the right pulmonary artery, with additional procedures as necessary. RESULTS There have been 3 deaths. Two patients died in the perioperative period of heart failure and massive effusions. The third patient died suddenly 8 months after the operation. All surviving patients were in New York Heart Association class I (n = 20) or II (n = 7), except for 1 patient who underwent heart transplantation. Early postoperative arrhythmias occurred in 10 patients: 4 required pacemakers, and medical therapy was sufficient in 6. In 15 patients, pre-revision arrhythmias were improved. Effusions resolved in all but 1 of the patients in whom they were present before revision. The condition of 2 patients with protein-losing enteropathy improved within 30 days. CONCLUSIONS Conversion of a failing Fontan connection to extracardiac cavopulmonary connection can be achieved with low morbidity and mortality. Optimally, revision should be undertaken early in symptomatic patients before irreversible ventricular failure ensues.

Congenital Heart Surgery Nomenclature and Database Project: anomalies of the coronary arteries

The extant nomenclature for coronary artery anomalies is reviewed for the purpose of establishing a unified reporting system. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery. All efforts were made to include all relevant nomenclature categories using synonyms where appropriate. The seven major categories of coronary artery anomalies are: anomalous pulmonary artery origins of the coronaries, anomalous aortic origins of the coronaries, congenital atresia of the left main coronary artery, coronary artery fistulas, coronary artery bridging, coronary aneurysms, and coronary stenosis. A comprehensive database set is presented which is based on a hierarchical scheme. Data are entered at various levels of complexity and detail, which can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analyses. A minimum database set is also presented, which will allow for data sharing and would lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.

Standardized multidisciplinary protocol improves handover of cardiac surgery patients to the intensive care unit.

Objectives: To determine whether the implementation of a standardized handover protocol could reduce the number of errors occurring during patient transitions from the operating room to the intensive care unit. Design: Prospective, interventional study. Setting: Pediatric cardiac intensive care unit. Subjects: Seventy-nine patient handovers in patients transitioning from the operating room to the cardiac intensive care unit after congenital cardiac surgery. Interventions: A preintervention assessment of patient handovers was obtained by direct observation using a standardized checklist. A teamwork-driven handover process and protocol was developed using traditional and novel quality-improvement techniques. The postimplementation observational assessment of handovers was performed using the same preintervention assessment tool. Preintervention and postintervention data metrics were analyzed and compared. Measurements and Main Results: Forty-one and 38 observations were performed in the preintervention and postintervention periods, respectively. Protocol implementation improved key areas of the handover process. Technical errors per handover were reduced from 6.24 to 1.52 (p < .0001), and critical verbal handoff information omissions were reduced from 6.33 to 2.38 (p < .0001) per handover. There was no change in duration of either the verbal handoff briefing or the overall handover process. Caregivers noted improvement in teamwork and handoff content received after the intervention. Conclusions: A formal, structured handover process for pediatric patients transitioning to the intensive care unit after cardiac surgery can reduce medical errors that occur during the admission process and improve teamwork among caregivers.

Tracheal surgery in children: an 18-year review of four techniques.

OBJECTIVE Review the short- and long-term outcomes of a single institution experience in infants with congenital tracheal stenosis, comparing four different operative techniques used from 1982 through 2000. METHODS Hospital and clinic records of 50 infants and children who had surgical repair of congenital tracheal stenosis secondary to complete tracheal rings were reviewed. Age at surgery ranged from 7 days to 72 months (median, 5 months, mean 7.8+/-12 months). Techniques included pericardial patch tracheoplasty (n=28), tracheal autograft (n=12), tracheal resection (n=8), and slide tracheoplasty (n=2). All procedures were done through a median sternotomy with cardiopulmonary bypass. Seventeen patients had a pulmonary artery sling (35%), and 11 had an intracardiac anomaly (22%). RESULTS There were three early deaths (6% early mortality), two after pericardial tracheoplasty and one after autograft. There were six late deaths (12% late mortality), five after pericardial tracheoplasty and one after slide tracheoplasty. Length of stay (median) was 60 days (pericardial tracheoplasty), 28 days (autograft), 14 days (resection), and 18 days (slide). Reoperation and/or stent placement was required in seven patients (25%) after pericardial tracheoplasty, in two patients (17%) after autograft, in no patients after resection, and in one patient (50%) after slide tracheoplasty. CONCLUSIONS Our current procedures of choice for infants with congenital tracheal stenosis are resection with end-to-end anastomosis for short-segment stenoses (up to eight rings) and the autograft technique for long-segment stenoses. Associated pulmonary artery sling and intracardiac anomalies should be repaired simultaneously.