Leland N. Benson

ABO-Incompatible heart transplantation in infants

BACKGROUND Transplantation of hearts from ABO-incompatible donors is contraindicated because of the risk of hyperacute rejection mediated by preformed antibodies in the recipient to blood-group antigens of the donor. This contraindication may not apply to newborn infants, who do not yet produce antibodies to T-cell-independent antigens, including the major blood-group antigens. METHODS We studied 10 infants 4 hours to 14 months old (median, 2 months) who had congenital heart disease or cardiomyopathy and who received heart transplants from donors of incompatible blood type between 1996 and 2000. Serum isohemagglutinin titers were measured before and after transplantation. Plasma exchange was performed during cardiopulmonary bypass; no other procedures for the removal of antibodies were used. Standard immunosuppressive therapy was given, and rejection was monitored by means of endomyocardial biopsy. The results were compared with those in 10 infants who received heart transplants from ABO-compatible donors. RESULTS The overall survival rate among the 10 recipients with ABO-incompatible donors was 80 percent, with 2 early deaths due to causes presumed to be unrelated to ABO incompatibility. The duration of follow-up ranged from 11 months to 4.6 years. Two infants had serum antibodies to antigens of the donors blood group before transplantation. No hyperacute rejection occurred; mild humoral rejection was noted at autopsy in one of the infants with antibodies. No morbidity attributable to ABO incompatibility has been observed. Despite the eventual development of antibodies to antigens of the donors blood group in two infants, no damage to the graft has occurred. Because of the use of ABO-incompatible donors, the mortality rate among infants on the waiting list declined from 58 percent to 7 percent. CONCLUSIONS ABO-incompatible heart transplantation can be performed safely during infancy before the onset of isohemagglutinin production; this technique thus contributes to a marked reduction in mortality among infants on the waiting list.

Echocardiographic follow-up of atrial septal defect after catheter closure by double-umbrella device.

BackgroundTranscatheter device occlusion of atrial septal defects is an attractive approach, but its efficacy and place in patient management remain to be determined. Methods and ResultsTo evaluate the medium-term results of atrial septal defect device occlusion and factors influencing residual shunting, transesophageal and transthoracic echocardiograms of 49 patients were reviewed. Transesophageal echocardiograms on 48 patients immediately following surgical closure revealed residual shunting in 2% compared with 91% after device occlusion; this proportion decreased to 53% after a mean follow-up of 10 months. The actuarial analysis suggests a progressive resolution of shunting with time. One patient had residual shunting by transesophageal echocardiography immediately after surgical closure compared with 29 after a mean follow-up of 10 months after device occlusion. Residual shunting was not influenced by (1) dimension, location, or position with relation to the device as assessed by transesophageal echocardiography; (2) location of the defect; or (3) device size relative to the stretched dimension of the defect. In 15 patients, a poor correlation existed between transesophageal and transthoracic echocardiographic findings. Variability in serial transthoracic echocardiographic findings was observed in 14. Right ventricular dimension, heart size, and presence of a murmur at follow-up did not correlate with the presence or size of residual shunting after device occlusion. ConclusionThese results suggest that ongoing spontaneous resolution of residual shunting occurs after device insertion. Factors related to the defect or device could not predict eventual resolution of residual shunting. Transthoracic echocardiography in the follow-up of these patients may not be reliable in determining presence of residual shunting.

Endovascular stents in the management of coarctation of the aorta in the adolescent and adult: one year follow up

OBJECTIVES To test the hypothesis that endovascular stents used with dilation of coarctation of the aorta (CoA) improve late outcomes. Balloon dilation for CoA has been limited by concerns over the risk for acute dissection, late restenosis, or aneurysm formation. DESIGN All patients seen with CoA between November 1994 and September 1997 underwent attempted stent implantation. Follow up was obtained for all patients and a subgroup (n = 18) had repeat catheterisation at a mean (SD) of 1.3 (0.5) years to assess residual gradient and stent-CoA morphology. RESULTS Stents were placed in 27 patients (15 male and 12 female patients, mean age 30.1 (13.1) years), of whom seven had prior surgical coarctectomy and one had a prior balloon dilation. Hypertension was present in 26 patients (mean pressure 164 (26)/86 (13) mm Hg), of whom 16 were on antihypertension drugs. CoA gradients were 46 (20) mm Hg (range 18–106 mm Hg) at baseline and 3 (5) mm Hg after the procedure. One patient had a stroke following the procedure; another patient had incomplete dilation and underwent a second procedure. At 1.8 (1) years after the procedure the mean pressure was 130 (14)/74 (11) mm Hg with seven patients on antihypertension treatment. The clinical gradient was 4 (8) mm Hg (range 0–32 mm Hg). At follow up angiography, the mean gradient was 4(6) mm Hg, and two patients had a gradient over 10 mm Hg. Aneurysms formed in three patients at the dilation site; one patient was referred for surgery. CONCLUSION In this age group stent management for CoA appears to be an effective technique and results in sustained reduction in CoA gradients at early term follow up, but aortic aneurysm was detected in 17% of patients who had repeat angiography.

Clinical outcomes of acute myocarditis in childhood

OBJECTIVE To describe clinical outcomes of a paediatric population with histologically confirmed lymphocytic myocarditis. DESIGN A retrospective review between November 1984 and February 1998. SETTING A major paediatric tertiary care hospital. PATIENTS 36 patients with histologically confirmed lymphocytic myocarditis. MAIN OUTCOME MEASURES Survival, cardiac transplantation, recovery of ventricular function, and persistence of dysrhythmias. RESULTS Freedom from death or cardiac transplantation was 86% at one month and 79% after two years. Five deaths occurred within 72 hours of admission, and one late death at 1.9 years. Extracorporeal membrane oxygenation support was used in four patients, and three patients underwent heart replacement. 34 patients were treated with intravenous corticosteroids. In the survivor/non-cardiac transplantation group (n = 29), the median follow up was 19 months (range 1.2–131.6 months), and the median period for recovery of a left ventricular ejection fraction to > 55% was 2.8 months (range 0–28 months). The mean (SD) final left ventricular ejection and shortening fractions were 66 (9)% and 34 (8)%, respectively. Two patients had residual ventricular dysfunction. No patient required antiarrhythmic treatment. All survivors reported no cardiac symptoms or restrictions in physical activity. CONCLUSIONS Our experience documents good outcomes in paediatric patients presenting with acute heart failure secondary to acute lymphocytic myocarditis treated with immunosuppression. Excellent survival and recovery of ventricular function, with the absence of significant arrhythmias, continued cardiac medications, or restrictions in physical activity were the normal outcomes.

Subaortic stenosis, the univentricular heart, and banding of the pulmonary artery: an analysis of the courses of 43 patients with univentricular heart palliated by pulmonary artery banding.

Subaortic stenosis is well known to complicate the clinical course of patients with single ventricle or univentricular hearts, and we have previously suggested that the development of subaortic stenosis in such patients may be causal to and/or accelerated by previous banding of the main pulmonary trunk. To further define the relationship between banding of the pulmonary artery in patients with univentricular hearts and the development of subaortic stenosis, we examined the morphologic substrate and timing of the development of subaortic stenosis in 43 patients seen at our institution from January 1, 1970, through June 30, 1985. These 43 patients include all patients in this period with an unequivocal univentricular heart whose longitudinal data was available for follow-up. We excluded patients who died within 1 week of surgery, patients lost to follow-up, and patients with evidence of subaortic stenosis before banding. Thirty-one of 43 patients (72.1%) developed subaortic stenosis subsequent to banding of the main pulmonary artery. The mean age at banding of those patients who developed subaortic stenosis was 0.21 years, and subaortic stenosis was recognized at a mean age of 2.52 years. For the specific cohort of patients whose ventricular morphology was a main chamber of left ventricular type supporting the pulmonary artery and a rudimentary right ventricle supporting the transposed aorta (32 patients), 27 developed subaortic stenosis (84.4%). Subaortic stenosis in the classic form of single ventricle usually results from progressive restriction of a wholly muscular interventricular communication. Banding of the pulmonary artery by producing myocardial hypertrophy undoubtedly accelerates the potential for subaortic stenosis in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Right ventricular form and function after percutaneous atrial septal defect device closure

OBJECTIVES We sought to assess the right hearts response to percutaneous device closure of moderate sized atrial septal defects (ASDs) in adults over a one-year follow-up period. BACKGROUND Percutaneous ASD device closure is a safe and effective means of reducing or eliminating interatrial shunting. The response of the adults right heart to device closure is incompletely understood. METHODS Forty consecutive patients had 40 device implantations (32 with the CardioSeal implant and 8 with the Amplatzer device). The patients were assessed with echocardiography, chest radiography and electrocardiography before the procedure and at 1, 6 and 12 months. RESULTS The mean ASD size was 13+/-4 mm, and the device size ranged from 33 to 40 mm for CardioSeal and 12 to 36 mm for Amplatzer. At one month, heart size (49% vs. 46%), four-chamber right ventricular (RV) size (45 vs. 41 mm), paradoxical septal motion (60% vs. 5%), QRS duration (125 vs. 119 ms), PR interval (181 vs. 155 ms) and echocardiographically determined pulmonary artery systolic pressure decreased significantly and was maintained at 12-month follow-up. At six months, right atrial length decreased from 50 to 47 mm. At one year, 29% of patients had persistent RV enlargement. CONCLUSIONS Right heart morphology undergoes rapid improvement within one month of defect closure, with associated mechanoelectrical benefit. A small number of patients had persistent RV enlargement or pulmonary hypertension, or both, at one year. Our data support the application of transcatheter methods in achieving excellent hemodynamic and anatomic outcomes.

Iliofemoral arterial complications of balloon angioplasty for systemic obstructions in infants and children.

The medical and radiological records of 64 consecutive infants and children who underwent transfemoral balloon dilation of the aorta or aortic valve were reviewed to determine the incidence, nature, and post-treatment outcome of acute iliofemoral complications. Balloon dilation angioplasty or balloon valvotomy was performed with 8F and 9F catheters without an arterial sheath. Patients ranged in age from 5 days to 15.4 years (mean, 6.4 years). Of 64 patients, 29 (45.3%) had an acute iliofemoral complication, including thrombosis (18 of 64), complete disruption (five of 64), incomplete disruption (three of 64), and arterial tear (three of 64). The arterial pathology was confirmed in 23 of 29 patients by one or a combination of surgical exploration and repair (18 of 29), angiography (six of 29), and magnetic resonance imaging (three of 29). Of eight patients, three with arterial disruption had acute hypotension requiring transfusion and immediate surgery; the other five had absent pedal pulses after the procedure. Of these five, three developed bleeding during thrombolytic therapy and underwent surgical exploration, and two were diagnosed by angiography after ineffective thrombolytic therapy. Angiography in three patients with iliac artery avulsion showed tapered occlusion in two and an aneurysm in one. In patients with iliofemoral thrombosis, angiography showed occlusion from the puncture site to the origin of the external iliac artery. Eleven patients (17% of the entire group and 38% of the group with acute iliofemoral complications) had reduced or absent pedal pulses at the time of discharge. A significant correlation was found between increased incidence of iliofemoral thrombosis and disruption (as well as abnormal pedal pulses at hospital discharge) and low patient weight.

Transcatheter treatment of coarctation of the aorta: a review.

Coarctation of the aorta (CoA), is a discrete stenosis in the proximal thoracic aorta [55], first described by Morgagni at autopsy in 1760 [2]. Although at first glance a straightforward obstructive lesion, the anatomy, physiology, clinical presentation, and natural history vary substantially and have challenged the ingenuity of the cardiologist and surgeon with diagnostic dilemmas and management controversies. The first surgical repair was performed by Crafoord in 1944 [32]. Since that description was published, a plethora of surgical techniques has been described, each building upon the other to improve immediate results and long-term outcomes. The pivotal role played by arterial duct tissue in the pathogenesis of CoA in the newborn was underscored [54, 105], when in the 1970s, prostaglandin E1 administration was added to the management armamentarium for neonates, further contributing to improved survival rates. In 1982, transcatheter balloon dilation was first described as a potential alternative to surgery [147]. Since that time, the literature has become replete with studies of surgical and balloon dilation results and attempted comparisons between techniques. Despite more than 5 decades of experience with numerous treatment modalities of this seemingly ‘‘simple’’ lesion, there continues to be considerable discussion on what is the ‘‘best’’ therapeutic approach for the pediatric and adult patient. The flames of such controversies are fanned not only by the interpretation of immediate and medium-term hemodynamic results and procedural risks, but also by the way the treatment, modulated by its ‘‘natural’’ history [43, 44, 69, 76, 77, 79], affects long-term results, and most significantly, by personal bias.

Differential Regurgitation in Branch Pulmonary Arteries After Repair of Tetralogy of Fallot. A Phase-Contrast Cine Magnetic Resonance Study

Background The importance of pulmonary regurgitation (PR) after repair of tetralogy of Fallot (TOF) is increasingly recognized, but little is known regarding its underlying mechanisms. This phase‐contrast cine magnetic resonance (PC MR) study was performed to evaluate the relative contribution of each lung to total regurgitant volume. Methods and Results Twenty‐two patients with significant PR underwent a PC MR 3 to 16 years after repair of TOF. Regurgitant fraction of the main pulmonary artery was 39±10%. Regurgitant fraction of the left pulmonary artery (LPA; 46±18%) was greater than that of the right pulmonary artery (34±16%; P=0.002). The average contribution of the LPA to the total regurgitant flow volume was 54±19%, whereas its average contribution to the total forward flow volume was 44±13% (P=0.002). In 4 patients, regurgitant flow in the LPA accounted for 75% to 100% of the total regurgitant flow. There was a linear relationship between regurgitant fraction and fraction of the regurgitant flow duration in the main pulmonary artery (P<0.001) and right pulmonary artery (P=0.001) but not in the LPA (P=0.129). Conclusions PR after repair of TOF is commonly associated with differential regurgitation in the branch pulmonary arteries, which is usually greater in the LPA. Although the cause of this disparity requires further investigation, those patients with a significant unilateral contribution to total PR may be amenable to localized techniques to reduce regurgitation. (Circulation. 2003;107:2938‐2943.)

Symptomatic atrial arrhythmias and transcatheter closure of atrial septal defects in adult patients

Objective: To determine whether transcatheter device closure of a secundum atrial septal defect (ASD) will reduce the risk of developing subsequent atrial arrhythmias. Design: The incidence and predictors of symptomatic atrial tachyarrhythmias (AT) were examined in adults undergoing transcatheter closure of ASDs. Setting: Toronto Congenital Cardiac Centre for Adults. Patients: 132 consecutive patients, mean (SD) age 44 (16) years; 74% female. Main outcome measure: Sustained or symptomatic atrial arrhythmias at early follow up (six weeks; n  =  115) and intermediate follow up (last clinic visit 17 (11) months post surgery; n  =  121). Results: 15% of the patients (20 of 132) had AT before the procedure (14 paroxysmal, six persistent). Patients without a history of arrhythmia had a low incidence of AT during early follow up (6%) and intermediate follow up (1%/year), while all patients with persistent AT before closure remained in atrial fibrillation or flutter. Of patients in sinus rhythm but with a previous history of AT, two thirds remained arrhythmia-free at follow up, with overall incidences of paroxysmal and persistent AT of 17%/year and 11%/year. A history of AT before closure (risk ratio (RR) 35.0, 95% confidence interval (CI) 7.2 to 169.0) and age ⩾ 55 years at the time of device insertion (RR 5.6, 95% CI 1.2 to 25.0) predicted AT after closure. Conclusions: Device closure of an ASD before the onset of atrial arrhythmias may protect against the subsequent development of arrhythmia, in particular in patients less than 55 years of age.