Orthotopic heart transplant in a pediatric patient with mixed connective tissue disease

BACKGROUND

Patients with autoimmune inflammatory syndromes such as mixed connective tissue disease (MCTD) and systemic lupus erythematosus have previously been considered marginal candidates for orthotopic heart transplant (OHT).

METHODS

A retrospective chart review was completed for this case report.

RESULTS

We present the case of an 11-year-old girl with known MCTD who developed congestive heart failure refractory to medical therapy and underwent OHT.

CONCLUSIONS

Despite her autoimmune condition, this patient has not experienced antibody-mediated rejection post-transplant and her inflammatory symptoms have greatly improved.

Bacterial infections after pediatric heart transplantation: Epidemiology, risk factors and outcomes

BACKGROUND

Bacterial infections represent a major cause of morbidity and mortality in heart transplant recipients. However, data describing the epidemiology and outcomes of these infections in children are limited.

METHODS

We analyzed the Pediatric Heart Transplant Study database of patients transplanted between 1993 and 2014 to determine the etiologies, risk factors and outcomes of children with bacterial infections post-heart transplantation.

RESULTS

Of 4,458 primary transplants in the database, there were 4,815 infections that required hospitalization or intravenous therapy, 2,047 (42.51%) of which were bacterial. The risk of bacterial infection was highest in the first month post-transplant, and the bloodstream was the most common site (24.82%). In the early post-transplant period (<30 days post-transplant), coagulase-negative staphylococci were the most common pathogens (16.97%), followed by Enterobacter sp (11.99%) and Pseudomonas sp (11.62%). In the late post-transplant period, community-acquired pathogens Streptococcus pneumoniae (6.27%) and Haemophilus influenzae (2.82%) were also commonly identified. Patients' characteristics independently associated with acquisition of bacterial infection included younger age (p < 0.0001) and ventilator (p < 0.0001) or extracorporeal membrane oxygenation (p = 0.03) use at time of transplant. Overall mortality post-bacterial infection was 33.78%, and previous cardiac surgery (p < 0.001) and multiple sites of infection (p = 0.004) were independent predictors of death.

CONCLUSIONS

Bacteria were the most common causes of severe infections in pediatric heart transplant recipients and were associated with high mortality rates. The risk of acquiring a bacterial infection was highest in the first month post-transplant, and a large proportion of the infections were caused by multidrug-resistant pathogens.

Dilated cardiomyopathy with cardiogenic shock in a child with Kearns-Sayre syndrome

Kearns-Sayre syndrome (KSS) is a mitochondrial myopathy resulting from mitochondrial DNA deletion. This syndrome primarily involves the central nervous system, eyes, skeletal muscles and the heart. The most well-known cardiac complications involve the conduction system; however, there have been case reports describing cardiomyopathy. We describe a case of a child with KSS who presented with decompensated cardiac failure from dilated cardiomyopathy representing cardiomyocyte involvement of KSS. Our patient had a rapidly progressing course, despite maximal medical management, requiring emergent institution of extracorporeal membrane oxygenation and transition to a ventricular assist device. To the best of our knowledge, this is the youngest patient in the literature to have dilated cardiomyopathy in KSS.

Impact of pulmonary hypertension on transplant outcomes in pediatric cardiomyopathy patients

Controversy exists over whether PHTN in heart transplant candidates increases post-transplant mortality. We performed analysis of data reported to UNOS for children who underwent primary heart transplantation for cardiomyopathy from January 1994 to June 2010. Patients were divided into two groups depending on their pre-transplant TPG: no-PHTN (TPG ≤ 12 mmHg) and PHTN (TPG >12 mm Hg). A total of 6139 children underwent transplantation of whom 2456 (40%) were for cardiomyopathies; 1322 (54%) of these had catheterization data available. The PHTN group (mean TPG 19.5 ± 8.6) had 312 patients and no-PHTN (TPG 6.7 ± 4.0) had 1010. Mortality at one month (4.5% vs. 2.3%) and three months (6.1% vs. 3.1%) post-transplant was significantly higher in the PHTN than the no-PHTN group with an odds ratio of 2 (p < 0.05). There was no significant effect of PHTN on early mortality in children <1 yr age. There was no significant improvement in early survival for transplants performed after compared to before 2003 in patients with PHTN despite availability of pulmonary dilators. Pre-transplant PHTN increases early post-transplant mortality in pediatric cardiomyopathy patients above one yr of age. There has been no significant improvement in the outcome of this group over the last seven yr.

Impact of donor cardiopulmonary resuscitation on pediatric heart transplant outcome

Mortality is the highest of any solid organ in pediatric patients awaiting heart transplantation. Strategies to increase the donor pool are needed if survival to transplant is to improve. There can be reluctance to accept pediatric hearts for transplantation if the donor has received cardiopulmonary resuscitation (CPR). This study asked if donor CPR impacts the survival of pediatric heart transplant recipients. Analysis of the UNOS database was performed for all cardiac transplants performed in patients aged 0-18 yr, with donors classified as to whether they received CPR (CPR+) or not (CPR-). We compared overall survival and survival at 30 days, one yr, and five yr between groups. Within the CPR+ group, the impact of duration of CPR on survival was compared. The need for inotropic support and ejection fraction was compared between donor groups as a measure of organ function. Overall survival and survival at 30 days, one yr, and five yr did not differ in the CPR+ compared to the CPR- group. Within the CPR+ group, duration of CPR was unrelated to post-transplant survival. The need for inotropic support at procurement was similar, and ejection fraction did not differ between the CPR+ and CPR- groups. Donor CPR does not have a negative impact on pediatric heart transplant survival.

Measuring stress velocity index using mean blood pressure: simple yet accurate?

The stress velocity index, or the relationship of the rate-corrected mean velocity of circumferential shortening (VCFc) to the end systolic wall stress (ESWS), is a sensitive, load-independent measure of left ventricular contractility. ESWS is technically difficult to obtain and requires simultaneous blood pressure measurement, carotid artery tracing, and phonocardiogram. We report our comparison of two simpler methods of measuring ESWS and, therefore, stress velocity index. Patients with normal cardiac anatomy who had completed anthracycline chemotherapy were evaluated. ESWS as measured by the standard method using a carotid artery tracing (ESWScar) was compared to ESWS obtained using mean arterial pressure (ESWSmap) or systolic blood pressure (ESWSsbp). The cohort included 63 patients, with 37 (59%) males and a median age of 13.1 years. The mean (+/-SD) ESWScar was 53.3+/-15.3 g/cm(2) (range, 26.3-94 g/cm(2)); ESWSmap, 53 +/-13.4 g/cm(2) (range, 27.1-86.1 g/cm(2)); and ESWSsbp, 72.9 +/- 18.2 g/cm(2) (range, 40.8-117.2 g/cm(2)). ESWSmap and ESWSsbp closely correlated with ESWScar (coefficient correlation r = 0.88 and r = 0.87, respectively). Using ESWSmap, all patients were correctly classified as having normal or abnormal contractility as defined by stress velocity index, whereas ESWSsbp detected only two of the six patients with impaired contractility. We conclude that ESWSmap is a simple, highly sensitive and specific method for assessing left ventricular contractility. ESWSmap correlates closely with ESWScar and can be incorporated into the monitoring of cardiac dysfunction in the anthracycline-treated population. Further studies are needed to determine if this simplified measure accurately assesses the ESWS in other cardiac disease states.

B-type natriuretic peptide as a marker for cardiac dysfunction in anthracycline-treated children

BACKGROUND

Anthracyclines (AC) are useful antineoplastic agents, whose utility is limited by progressive cardiotoxicity. Our purpose was to evaluate plasma B-type natriuretic peptide (BNP), as a screening test for detecting late cardiac dysfunction in AC-treated children and to determine the prevalence of late cardiac dysfunction at low cumulative AC doses.

MATERIALS AND METHODS

This was a prospective study in which patients who had completed AC therapy at least 1 year earlier, underwent a detailed echocardiogram and a simultaneous BNP level. Cardiac dysfunction was defined as any one of the following: shortening fraction (FS) <29%, rate corrected velocity of circumferential fiber shortening (VCFc) <0.9 c x sec(-1), end systolic wall stress (ESWS) >60 g x cm(-2), abnormal VCFc: ESWS ratio or decreased mitral inflow velocity (E/A) ratios, compared to age-specific norms.

RESULTS

The cohort (n = 63) included 37 males with a median age of 13.1 years (range, 6.5-26.5 years). Cardiac dysfunction was found in 26 (41%) patients and in 40% of patients who received cumulative doses <150 mg x m(-2). ESWS was the most common abnormality. Mean BNP levels in the subset with abnormal function were significantly higher than the normal group (23.4 +/- 25.3 vs. 14.2 +/- 8.9 pg x ml(-1), P = 0.02).

CONCLUSIONS

Plasma BNP was significantly elevated in AC-treated patients with late cardiac dysfunction, although there was considerable overlap of levels between groups with and without cardiac dysfunction. BNP may need further evaluation as a serial index of cardiac function in this population. Cardiac dysfunction was observed in a significant proportion of patients, even at low cumulative AC doses.

DNA damage is an early event in doxorubicin-induced cardiac myocyte death

Anthracyclines are antitumor agents the main clinical limitation of which is cardiac toxicity. The mechanism of this cardiotoxicity is thought to be related to generation of oxidative stress, causing lethal injury to cardiac myocytes. Although protein and lipid oxidation have been documented in anthracycline-treated cardiac myocytes, DNA damage has not been directly demonstrated. This study was undertaken to determine whether anthracyclines induce cardiac myocyte DNA damage and whether this damage is linked to a signaling pathway culminating in cell death. H9c2 cardiac myocytes were treated with the anthracycline doxorubicin at clinically relevant concentrations, and DNA damage was assessed using the alkaline comet assay. Doxorubicin induced DNA damage, as shown by a significant increase in the mean tail moment above control, an effect ameliorated by inclusion of a free radical scavenger. Repair of DNA damage was incomplete after doxorubicin treatment in contrast to the complete repair observed in H2O2-treated myocytes after removal of the agent. Immunoblot analysis revealed that p53 activation occurred subsequent in time to DNA damage. By a fluorescent assay, doxorubicin induced loss of mitochondrial membrane potential after p53 activation. Chemical inhibition of p53 prevented doxorubicin-induced cell death and loss of mitochondrial membrane potential without preventing DNA damage, indicating that DNA damage was proximal in the events leading from doxorubicin treatment to cardiac myocyte death. Specific doxorubicin-induced DNA lesions included oxidized pyrimidines and 8-hydroxyguanine. DNA damage therefore appears to play an important early role in anthracycline-induced lethal cardiac myocyte injury through a pathway involving p53 and the mitochondria.

Role of plasma B-type natriuretic peptide in screening for hemodynamically significant patent ductus arteriosus in preterm neonates

BACKGROUND

B-type natriuretic peptide (BNP) is a hormone secreted by the ventricles under hemodynamic stress and congestive failure.

OBJECTIVE

The objective of the present study was to evaluate whether BNP can be used as a valid screening test for the presence of a hemodynamically significant patent ductus arteriosus (hsPDA) in the preterm neonate.

MATERIALS AND METHODS

This was a prospective blinded study involving preterm neonates with birth weights <or=1500 g and gestational age <or=34 weeks. Each enrolled neonate underwent the initial echocardiogram for a clinical suspicion of patent ductus arteriosus (PDA) and BNP assay within 3 hours of each other. Those neonates who did not have a PDA or who were not treated underwent a repeat echo and BNP measurement 48 to 72 hours after the first echo. In patients who received treatment for a PDA, an echo and BNP were repeated 48 to 72 hours after completion of treatment.

RESULTS

A total of 29 newborns with a median birth weight of 870 g (560 to 1325 g) and a median gestation of 26 weeks (24 to 31 weeks) were enrolled at a median age of 7 days (2 to 28 days). BNP levels were significantly higher in neonates with hsPDA (n=14) compared to those without (n=15) (508.5+/-618.2 vs 59.5+/-69.9 pg/ml, p<0.005). At a cutoff value of 70 pg/ml, BNP had a sensitivity of 92.9%, specificity of 73.3%, positive likelihood ratio of 3.5 and negative likelihood ratio of 0.09 for detection of hsPDA. BNP levels dropped significantly after medical or surgical closure of hsPDA (n=12), (404.9+/-159.2 to 25.1+/-4.1 pg/ml, p=0.03).

CONCLUSIONS

Elevation of plasma BNP accurately detects the presence of hsPDA in premature infants. Successful closure is reflected by a corresponding decrease in BNP. At a cutoff of 70 pg/ml, BNP is a useful screening tool for diagnosis and for monitoring efficacy of treatment of hsPDA.

Glutathione S-transferase overexpression protects against anthracycline-induced H9C2 cell death

Anthracyclines (AC) are antitumor antibiotics with significant activity against solid and hematologic malignancies. One problem preventing more widespread use has been the development of cardiac toxicity. Experimental evidence supports oxidant stress as an important trigger and/or mediator of AC-induced cardiotoxicity (ACT). Therefore, reducing oxidant stress should be protective against ACT. To determine whether antioxidant protein overexpression can reduce ACT, we developed a cell culture model system using the H9C2 cardiac cell line exhibiting controlled overexpression of the α4-isoform of glutathione- S-transferase (GST). Treatment with the AC doxorubicin (DOX) produced both oncosis, manifested by an increase in the number of cells staining positive for Trypan blue, and apoptosis, indicated by the presence of positive terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. In both cases, the loss of cell viability was preceded by an AC-induced increase in fluorescence with carboxy-2′,7′-dichlorofluorescein diacetate, demonstrating the presence of high levels of reactive oxygen species (ROS). The DOX-induced increase in ROS was reduced to control levels by maximal GST overexpression. Coincident with this elimination of oxidative stress, there was a reduction in both Trypan blue and TUNEL-positive cells, indicating that GST overexpression reduced both ROS and cell death in this model system. We conclude that GST overexpression may be an important part of a protective strategy against ACT and that this model system will aid in defining steps in the pathway(s) leading to AC-induced cell death that can be therapeutically manipulated.

Effect of increased expression of cytoskeletal protein vinculin on ischemia-reperfusion injury in ventricular myocytes

The transition from reversible to irreversible ischemic injury (ischemia-reperfusion, I/R) occurs coincident with the loss of vinculin, a cytoskeletal protein involved in the attachment of the myofibrils to the sarcolemmal membrane. If the loss of vinculin were critical to the development of I/R, then increased levels of vinculin would be predicted to delay the onset of irreversible injury assuming that the protein is functional and localized to the proper subcellular site. The present study determined whether increased expression of vinculin, specifically in the cytoskeletal compartment, would provide protection from I/R injury. Neonatal rat myocytes were cultured and infected with a newly created replication-deficient adenovirus driving the expression of vinculin. I/R was induced with chemical inhibitors of glycolysis and mitochondrial respiration. Irreversible cell injury was assessed with lactate dehydrogenase (LDH) release. Virus-infected myocytes expressed significantly more vinculin in the cytoskeletal fraction and increased the expression of paxillin but sustained the same amount of injury in response to simulated I/R as control cells (n = 4; P = not significant, paired t-test). Hypothermic I/R (ischemia at 25 degrees C) resulted in a significant reduction in LDH release (P </= 0.02; n = 4). Virus-mediated overexpression of vinculin does not appear to represent a rational approach to overcoming I/R injury.

Anthracycline-induced cardiac injury using a cardiac cell line: potential for gene therapy studies

Anthracyclines are effective antitumor agents whose chief limitation has been cardiotoxicity directly related to free radical production. Therefore, strategies designed to selectively overexpress antioxidant proteins in the heart could protect against drug-induced toxicity and allow higher doses of chemotherapy. However, to date an adequate cardiac model system that is susceptible to anthracycline injury and can express foreign genes in a controlled fashion has been lacking. Developing a cardiac model system would permit examination of the relationship between the expression level of a potentially protective foreign gene and the degree of protection from injury. In this study we have examined the potential of the H9C2 rat cardiac myocyte cell line in this regard. H9C2 cells differentiate in a reproducible fashion, as shown by progressive increases in muscle tropomyosin-expressing cells, the organization of this thin filament protein, and the percentage of muscle cells contained within myotubes. Exposure of this cell line to the anthracycline doxorubicin produces cell injury as indicated by release of the intracellular enzyme lactate dehydrogenase into the culture medium. This injury is preceded by generation of reactive oxygen species, indicated by fluorescence after loading with carboxy-dichlorodihydrofluorescein diacetate. Stable transfection of H9C2 cells with a plasmid producing a tetracycline transactivator protein allows foreign genes to be expressed at a level tightly controlled by the concentration of tetracycline in the culture medium. Since H9C2 cells differentiate, can be injured by anthracycline exposure, and can express foreign genes at controllable levels, this is a suitable system in which to design genetic approaches to prevent this important clinical problem.

Long-term follow-up of extended aortoplasty for supravalvular aortic stenosis

Extended aortoplasty is an operation that was designed to provide a symmetric reconstruction of the aortic root in patients with supravalvular aortic stenosis. The aim of this report is to provide long-term follow-up of the original cohort of 15 patients who underwent extended aortoplasty between 1975 and 1983. Follow-up was obtained in 14 patients. One patient was lost to follow-up 3 years after operation; he was included in this report. An echocardiogram, chest radiograph, and electrocardiogram were obtained for each surviving patient. The median length of follow-up was 141 months (range 36 to 238). The median preoperative gradient was 90 mm Hg (range 55 to 150). The median immediate postoperative gradient was 20 mm Hg (range 0 to 50, p < 0.05 compared with preoperative gradient) and the median long-term gradient was 32 mm Hg (range 6 to 96, p < 0.05 compared with preoperative gradient; p = not significant compared with immediate postoperative gradient). Two patients died: one of left ventricular failure after a subsequent aortic valve replacement and one of chronic left ventricular failure. The Kaplan-Meier estimate of survival at 218 months for all patients was 77.4% (70% confidence limits 62% to 93%). The estimated freedom from reoperation for all patients was 69% at 218 months (70% confidence limits 56% to 82%). Univariate analysis revealed that the presence of a bicuspid valve is a significant risk factor for reoperation (p = 0.038), but not for death (p = 0.51). The Kaplan-Meier estimate of freedom from reoperation for patients with a bicuspid aortic valve was 42.9% at 141 months (70% confidence limits 21% to 65%). Extended aortoplasty provides effective long-term relief of the pressure gradient across the supravalvular ridge. However, a significant number of patients require subsequent operations, particularly those with a bicuspid aortic valve.