Angela Lorts

Left ventricular non-compaction cardiomyopathy

Left ventricular non-compaction, the most recently classified form of cardiomyopathy, is characterised by abnormal trabeculations in the left ventricle, most frequently at the apex. It can be associated with left ventricular dilation or hypertrophy, systolic or diastolic dysfunction, or both, or various forms of congenital heart disease. Affected individuals are at risk of left or right ventricular failure, or both. Heart failure symptoms can be induced by exercise or be persistent at rest, but many patients are asymptomatic. Patients on chronic treatment for compensated heart failure sometimes present acutely with decompensated heart failure. Other life-threatening risks of left ventricular non-compaction are ventricular arrhythmias or complete atrioventricular block, presenting clinically as syncope, and sudden death. Genetic inheritance arises in at least 30-50% of patients, and several genes that cause left ventricular non-compaction have been identified. These genes seem generally to encode sarcomeric (contractile apparatus) or cytoskeletal proteins, although, in the case of left ventricular non-compaction with congenital heart disease, disturbance of the NOTCH signalling pathway seems part of a final common pathway for this form of the disease. Disrupted mitochondrial function and metabolic abnormalities have a causal role too. Treatments focus on improvement of cardiac efficiency and reduction of mechanical stress in patients with systolic dysfunction. Further, treatment of arrhythmia and implantation of an automatic implantable cardioverter-defibrillator for prevention of sudden death are mainstays of therapy when deemed necessary and appropriate. Patients with left ventricular non-compaction and congenital heart disease often need surgical or catheter-based interventions. Despite progress in diagnosis and treatment in the past 10 years, understanding of the disorder and outcomes need to be improved.

Large-scale serum protein biomarker discovery in Duchenne muscular dystrophy

Significance Duchenne muscular dystrophy (DMD) is a rare and devastating muscle disease caused by mutations in the X-linked DMD gene (which encodes the dystrophin protein). Serum biomarkers hold significant potential as objective phenotypic measures of DMD disease state, as well as potential measures of pharmacological effects of and response to therapeutic interventions. Here we describe a proteomics approach to determine serum levels of 1,125 proteins in 93 DMD patients and 45 controls. The study identified 44 biomarkers that differed significantly between patients and controls. These data are being made available to DMD researchers and clinicians to accelerate the search for new diagnostic, prognostic, and therapeutic approaches. Serum biomarkers in Duchenne muscular dystrophy (DMD) may provide deeper insights into disease pathogenesis, suggest new therapeutic approaches, serve as acute read-outs of drug effects, and be useful as surrogate outcome measures to predict later clinical benefit. In this study a large-scale biomarker discovery was performed on serum samples from patients with DMD and age-matched healthy volunteers using a modified aptamer-based proteomics technology. Levels of 1,125 proteins were quantified in serum samples from two independent DMD cohorts: cohort 1 (The Parent Project Muscular Dystrophy–Cincinnati Children’s Hospital Medical Center), 42 patients with DMD and 28 age-matched normal volunteers; and cohort 2 (The Cooperative International Neuromuscular Research Group, Duchenne Natural History Study), 51 patients with DMD and 17 age-matched normal volunteers. Forty-four proteins showed significant differences that were consistent in both cohorts when comparing DMD patients and healthy volunteers at a 1% false-discovery rate, a large number of significant protein changes for such a small study. These biomarkers can be classified by known cellular processes and by age-dependent changes in protein concentration. Our findings demonstrate both the utility of this unbiased biomarker discovery approach and suggest potential new diagnostic and therapeutic avenues for ameliorating the burden of DMD and, we hope, other rare and devastating diseases.

Genetic Manipulation of Periostin Expression in the Heart Does Not Affect Myocyte Content, Cell Cycle Activity, or Cardiac Repair

Following a pathological insult, the adult mammalian heart undergoes hypertrophic growth and remodeling of the extracellular matrix. Although a small subpopulation of cardiomyocytes can reenter the cell cycle following cardiac injury, the myocardium is largely thought to be incapable of significant regeneration. Periostin, an extracellular matrix protein, has recently been proposed to induce reentry of differentiated cardiomyocytes back into the cell cycle and promote meaningful repair following myocardial infarction. Here, we show that although periostin is induced in the heart following injury, it does not stimulate DNA synthesis, mitosis, or cytokinesis of cardiomyocytes in vitro or in vivo. Mice lacking the gene encoding periostin and mice with inducible overexpression of full-length periostin were analyzed at baseline and after myocardial infarction. There was no difference in heart size or a change in cardiomyocyte number in either periostin transgenic or gene-targeted mice at baseline. Quantification of proliferating myocytes in the periinfarct area showed no difference between periostin-overexpressing and -null mice compared with strain-matched controls. In support of these observations, neither overexpression of periostin in cell culture, via an adenoviral vector, nor stimulation with recombinant protein induced DNA synthesis, mitosis, or cytokinesis. Periostin is a regulator of cardiac remodeling and hypertrophy and may be a reasonable pharmacological target to mitigate heart failure, but manipulation of this protein appears to have no obvious effect on myocardial regeneration.

Pediatric heart transplant waiting list mortality in the era of ventricular assist devices

BACKGROUND Earlier reviews have reported unacceptably high incidence of pediatric heart transplant (PHT) waiting list mortality. An increase in ventricular assist devices (VAD) suggests a potential positive effect. This study evaluated PHT waiting list mortality in the era of pediatric VADs. METHODS United Network of Organ Sharing (UNOS) database from 1999 to 2012 showed 5,532 pediatric candidates (aged ≤ 18 years) actively listed for PHT: 2,191 were listed in 1999 to 2004 (Era 1) and 3,341 were listed in 2005 to 2012 (Era 2). RESULTS Waiting list mortality was lower in Era 2 (8%) vs Era 1 (16%; p < 0.001). VAD therapy was used more frequently in Era 2 (16%) than in Era 1 (6%; p < 0.001) and was associated with better waiting list survival (p < 0.001). There were more UNOS Status 1A patients in Era 2 (80%) vs Era 1 (68%; p < 0.001). Independent predictors of waiting list mortality included weight < 10 kg (odds ratio [OR], 2.7 95% confidence interval [CI], 1.1-6.9), congenital heart disease diagnosis (OR, 2.4; 95% CI, 1.9-3.0), blood type O (OR, 2.2; 95% CI, 1.8-2.8)], extracorporeal membrane oxygenation (OR, 1.5; 95% CI, 1.1-2.2), mechanical ventilation (OR, 1.8; 95% CI, 1.4-2.3), and renal dysfunction (OR 1.6; 95% CI, 1.2-2.0). Independent predictors of survival on the waiting list included VAD therapy (OR 4.2; 95% CI, 2.4-7.6), cardiomyopathy diagnosis (OR 3.3; 95% CI, 2.4-4.6), blood type A (OR, 2.2; 95% CI, 1.8-2.8), UNOS list Status 1B (OR, 1.9; 95% CI, 1.2-3.0), listed in Era 2 (OR 1.8; 95% CI, 1.4-2.2), and white race (OR 1.3; 95% CI, 1.1-1.6). CONCLUSIONS Despite an increase in the number of children listed as Status 1A, there was more than a 50% reduction in waiting list mortality in the new era. Irrespective of other factors, patients supported with a VAD were 4 times more likely to survive to transplant.

Implantation of the HeartMate II and HeartWare left ventricular assist devices in patients with duchenne muscular dystrophy: lessons learned from the first applications.

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder affecting 1 in 3,500 males, characterized by progressive skeletal muscle weakness and death secondary to cardiac or respiratory failure in the 2nd or 3rd decade. Being a progressive disease, patients are rarely candidates for cardiac transplantation and death from dilated cardiomyopathy (DCM) is common. Implantation of left ventricular assist device (LVAD) offers the potential to alter clinical trajectory by alleviating heart failure symptoms. We report implantation of HeartMate II device in a 29-year-old male patient and HeartWare device in a 23-year-old female patient, each with DMD and end-stage DCM. By improving cardiac output, we were able to achieve resolution of the symptoms of heart failure and improve their quality of life. Preoperative planning and patient selection played a significant role in the postoperative course for these patients. These cases represent the first use for each device in this patient population and the first reported LVAD implantations in patients with DMD in North America.

The evolving role of the total artificial heart in the management of end-stage congenital heart disease and adolescents.

Advances in medical therapies have yielded improvement in morbidity and a decrease in mortality for patients with congenital heart disease, both surgically palliated and uncorrected. An unintended consequence is a cohort of adolescent and adult patients with heart failure who require alternative therapies. One intriguing option is placement of a total artificial heart (TAH) either as a bridge to transplant or as a destination therapy. Of the 1091 Jarvik-7 type TAH (Symbion, CardioWest and SynCardia) placed between 1985 and 2012, only 24 have been performed in patients with congenital heart disease, and a total of 51 were placed in patients younger than 21. At our institution, the SynCardia TAH was implanted in a 19-year-old patient with cardiac allograft failure because of chronic rejection and related multisystem organ failure including need for hemodialysis. Over the next year, she was nutritionally and physically rehabilitated, as were her end organs, allowing her to come off dialysis, achieve normal renal function and eventually be successfully transplanted. Given the continued growth of adolescent and adult congenital heart disease populations with end-stage heart failure, the TAH may offer therapeutic options where previously there were few. In addition, smaller devices such as the SynCardia 50/50 will open the door for applications in smaller children. The Freedom Driver offers the chance for patients to leave the hospital with a TAH, as does the AbioCor, which is a fully implantable TAH option. In this report, we review the history of the TAH and potential applications in adolescent patients and congenital heart disease.

Left Ventricular Noncompaction Cardiomyopathy in Barth Syndrome: An Example of an Undulating Cardiac Phenotype Necessitating Mechanical Circulatory Support as a Bridge to Transplantation

Barth syndrome (BTHS) is associated with myocardial disease, frequently left ventricular noncompaction cardiomyopathy, which may necessitate cardiac transplantation or lead to death in some patients. We report a child with BTHS who had an “undulating cardiac phenotype” and ultimately developed decompensated heart failure requiring mechanical circulatory support with a ventricular assist device as a bridge to transplantation. His course was complicated by acute lung injury requiring placement of an in-line oxygenator to maintain end-organ function. Not only was his course complicated by cardiac and respiratory failure but his BTHS associated comorbidities complicated the management of his therapy using mechanical assist device support. He was successfully supported and subsequently was transplanted. Here we discuss the management of a child with BTHS using mechanical circulatory support and describe the use of an in-line oxygenator, Quadrox, with the Berlin Excor device.

Virtual implantation evaluation of the total artificial heart and compatibility: Beyond standard fit criteria

evaluated allosensitization much later after the NorwoodAG procedure and found that 56% were sensitized at median follow-up of 10.1 years. More importantly, almost all our sensitized Norwood-AG patients had very high PRA (HLA Class I or II antibody 450%) as compared with none in the Norwood-nonAG and hybrid groups. Mahle et al showed that patients with very high PRA has the highest risk of death after HTx. Although mortality was not significantly different between our study groups, this may become apparent in larger studies. The purpose of this study was to evaluate outcomes of alternative strategies in a group of patients with the highest risk of allosensitization and post-transplant mortality. Our results show that avoidance of allograft use at surgical palliation can lead to less allosensitization, less rejection and favorable posttransplant outcomes in infants with HLHS. Therefore, highrisk patients with HLHS, who are likely to require HTx early in life, may benefit from palliation with a hybrid procedure instead of a Norwood procedure as a bridge to transplant. Moreover, because many HLHS patients will eventually require HTx, aortic arch reconstruction with non-allograft material at time of Norwood palliation should be considered for standard risk patients as well.

Conduction Abnormalities in Pediatric Patients With Restrictive Cardiomyopathy

Background—Pediatric restrictive cardiomyopathy carries a poor prognosis secondary to a high risk of sudden death previously attributed to ventricular tachyarrhythmias. The extent of conduction abnormalities in this population and their relationship to life-threatening events has not been previously reported. Methods and Results—A retrospective study of pediatric patients with restrictive cardiomyopathy diagnosed between April 1994 and May 2011 was performed. Demographic, cardiac, and ECG characteristics and the mechanisms of serious arrhythmic events (death or episode of acute hemodynamic compromise thought to be secondary to arrhythmia) were evaluated. Sixteen patients (1–17 years of age) were reviewed, with 5 sudden cardiac events noted, including 4 deaths. Two deaths were caused by development of acute heart block; another patient with syncope had intermittent heart block and survived as the result of pacing features of an implanted defibrillator system. The median PR interval (222 versus 144 ms; P<0.01) and the QRS duration (111 versus 74; P=0.01) were significantly longer in those who had an acute cardiac event. Older age at presentation was associated with sudden cardiac events (P<0.01). No other functional or echocardiographic variables were associated with a sudden cardiac event. Conclusions—Pediatric patients with restrictive cardiomyopathy are at risk for acute high-grade heart block, and, in this cohort, bradycardic events represented a significant portion of all arrhythmic events. Aggressive ECG monitoring strategies looking for conduction system disease should be ongoing in all patients with restrictive cardiomyopathy. Implantation of a defibrillator/pacemaker should be considered as prophylactic management.

Current treatments for congenital aortic stenosis.

Purpose of review Congenital valvar aortic stenosis is a challenging disease that often requires repeated palliative procedures. Stenosis can range from mild and asymptomatic, not requiring intervention, to severe, as seen in hypoplastic left heart syndrome. New advances such as fetal balloon valvuloplasty, improvements in the Ross technique, and long-term studies of trans-catheter balloon valvuloplasty and surgical valvotomy warrant a review of the outcomes and optimal timing of the various interventions. Recent findings Fetal balloon valvuloplasty has shown promise. Despite some mortality and morbidity, some fetuses are showing significant growth in left ventricular structures, allowing biventricular repair. In neonates and infants with congenital aortic stenosis, excellent initial results are obtained with trans-catheter balloon valvuloplasty, although stenosis resistant to further balloon dilation or regurgitation may develop, necessitating surgical intervention. Midterm results from the Ross procedure are encouraging, demonstrating low rates of mortality, aortic insufficiency and re-intervention. Stenosis of the pulmonary allograft may be inevitable, and recent long-term follow-up suggests an increase in aortic insufficiency. Summary While availability of fetal balloon valvuloplasty is limited, it has promise for promoting in-utero left ventricle growth and improving function. The optimal procedure for infants and neonates is trans-catheter balloon valvuloplasty. For older patients, the Ross procedure is the repair of choice, although more long-term studies are needed to assess the natural course of the autograft. Outcomes should improve with advances in pulmonary allografts.