Improved Exercise Tolerance in an Adolescent Female After Failed Fontan and Subsequent Biventricular Conversion.

We report a case of improved exercise tolerance in a single-ventricle patient following biventricular conversion. An 11 year old with a fenestrated extracardiac failing Fontan was accepted for a biventricular conversion repair at an out-of-town institution. The patient had multiple adverse cardiac events following Fontan surgery including recurrent pleural effusions, arteriovenous malformations, protein-losing enteropathy, and marked exercise intolerance. Serial cardiac catheterizations revealed chronic elevated pulmonary artery and Fontan pressures, normal left ventricular end-diastolic pressure and an adequately sized left ventricle. Cardiopulmonary exercise testing demonstrated severely reduced exercise tolerance due to ventilatory and cardiac limitations with significant arterial desaturations during exercise. Following a successful biventricular conversion, exercise tolerance improved remarkably, as evidenced by improved oxygen uptake and ventilatory efficiency. Our case demonstrates that biventricular conversion surgery may offer improvement in quality of life and exercise capacity in selected patients with failing Fontan physiology.

Early Infantile Diagnosis of Hereditary Hemorrhagic Telangiectasia Complicated by Child Abuse.

We report a rare case of hereditary hemorrhagic telangiectasia (HHT) in a 4-month-old female infant with findings of child abuse. She presented with poor feeding, vomiting, and irritability after a short fall from the bed. Initial evaluation found subdural hematomas, persistent hypoxia, failure to thrive, a frenulum tear, facial lacerations, and bruising. The patient was admitted, and an extensive workup led to the diagnosis of brain and pulmonary arteriovenous malformations and finally the diagnosis of HHT. The subdural hematomas, cutaneous injuries, and oral injury were highly suspicious for child abuse and were reported to Child Protective Services and law enforcement for investigation simultaneous to the medical work-up. Her hospital course was complicated by progressive hypoxemia with radiographic evidence of several large pulmonary arteriovenous malformations, for which she underwent successful embolization. Her head injury was indeterminate for physical abuse in the setting of a medical condition predisposing to intracranial hemorrhage. A few weeks later, she was readmitted with repeat abusive injuries in the form of femur fractures. This case demonstrates the unique diagnostic dilemma when 2 diagnoses are occurring simultaneously-HHT and child abuse-and showcases the importance of a detailed family history, genetic testing, strong multidisciplinary collaboration with a holistic approach and medically informed Child Protective Services systems to ensure accurate diagnoses and safe disposition.

Structure of the C-terminal guanine nucleotide exchange factor module of Trio in an autoinhibited conformation reveals its oncogenic potential.

The C-terminal guanine nucleotide exchange factor (GEF) module of Trio (TrioC) transfers signals from the Gαq/11 subfamily of heterotrimeric G proteins to the small guanosine triphosphatase (GTPase) RhoA, enabling Gαq/11-coupled G protein-coupled receptors (GPCRs) to control downstream events, such as cell motility and gene transcription. This conserved signal transduction axis is crucial for tumor growth in uveal melanoma. Previous studies indicate that the GEF activity of the TrioC module is autoinhibited, with release of autoinhibition upon Gαq/11 binding. Here, we determined the crystal structure of TrioC in its basal state and found that the pleckstrin homology (PH) domain interacts with the Dbl homology (DH) domain in a manner that occludes the Rho GTPase binding site, thereby suggesting the molecular basis of TrioC autoinhibition. Biochemical and biophysical assays revealed that disruption of the autoinhibited conformation destabilized and activated the TrioC module in vitro. Last, mutations in the DH-PH interface found in patients with cancer activated TrioC and, in the context of full-length Trio, led to increased abundance of guanosine triphosphate-bound RhoA (RhoA·GTP) in human cells. These mutations increase mitogenic signaling through the RhoA axis and, therefore, may represent cancer drivers operating in a Gαq/11-independent manner.