Faculty Bibliography

Background: A recent multi-center study of perinatal outcome in fetuses with Ebstein anomaly or tricuspid valve dysplasia (EA/TVD) found that 1/3rd of live-born patients (pts) died prior to hospital discharge. The purpose of this study was to explore differences in postnatal management and the relationship to outcome. Methods: This 23-center, retrospective study included 243 fetuses with EA/TVD from 2005 to 2011. Neonatal procedure (NP) was defined as surgery or interventional catheterization (cath) prior to discharge. Associations between postnatal management and outcome at discharge were explored. Results: Of 176 live-born pts, 7 received comfort care only, 11 died <24 hrs of life, and 4 had insufficient data. Among 154 remaining pts, 38 (25%) did not survive to discharge. Pts who required ECMO at any point (n=18) had 83% mortality. More than half of pts (54%) did not have an NP, 34% had surgery, 8% had interventional cath, and 4% had both. The median age at 1st NP was 6 days (quartiles: 1-11). Survival did not differ between pts who had an NP and those who did not (70% vs. 80%; p=0.19) or between pts who had surgery and those who did not (68% vs. 80%; p=0.09). However, mortality differed by NP performed and whether pulmonary regurgitation, an indicator of high risk, was present prenatally (Figure). No pts with a right ventricular exclusion (RVE) died. Of 49 surviving neonates with >1 procedure, 28 (57%) were palliated with a shunt or RVE and 21 (43%) had a biventricular circulation. Thus, in total, 86 of 154 live-born pts (56%) survived with a biventricular circulation: 65 with medical management only and 21 with >1 NP. Conclusion: Among live-born pts diagnosed with EA/TVD in utero, a variety of postnatal management strategies were employed with overall poor outcomes. If surgery beyond PDA ligation is necessary, then RVE or other palliative procedure may need to be considered. A prospective, multi-center study utilizing a management algorithm would help elucidate the optimal strategy

Marfan syndrome (MFS) is an autosomal dominant disorder of connective tissue, caused by mutations of the microfibrillar protein fibrillin-1, that predisposes affected individuals to aortic aneurysm and rupture and is associated with increased TGFbeta signaling. TGFbeta is secreted from cells as a latent complex consisting of TGFbeta, the TGFbeta propeptide, and a molecule of latent TGFbeta binding protein (LTBP). Improper extracellular localization of the latent complex can alter active TGFbeta levels, and has been hypothesized as an explanation for enhanced TGFbeta signaling observed in MFS. We previously reported the absence of LTBP-3 in matrices lacking fibrillin-1, suggesting that perturbed TGFbeta signaling in MFS might be due to defective interaction of latent TGFbeta complexes containing LTBP-3 with mutant fibrillin-1 microfibrils. To test this hypothesis, we genetically suppressed Ltbp3 expression in a mouse model of progressively severe MFS. Here, we present evidence that MFS mice lacking LTBP-3 have improved survival, essentially no aneurysms, reduced disruption and fragmentation of medial elastic fibers, and decreased Smad2/3 and Erk1/2 activation in their aortas. These data suggest that, in MFS, improper localization of latent TGFbeta complexes composed of LTBP-3 and TGFbeta contributes to aortic disease progression.

Surgical repair of congenital ventricular septal defects (VSDs) in adults is quite rare. Most congenital VSDs are repaired in children. Of those adult patients diagnosed as having VSDs, many are not repaired due to irreversible pulmonary vascular disease. Repair in a patient with a VSD and fistula is even more uncommon. From a review of the literature, we found no other case reports with our unique combination of echocardiographic and surgical findings: a supracristal VSD, right and left sinus of Valsalva fistulas into the right ventricular outflow tract, and a pulmonary artery to pulmonary vein fistula in the context of an aseptic endocarditis lesion. We review the important aspects of anesthetic management in an adult with an intracardiac shunt. An adult patient with unrepaired congenital VSD may develop multiple fistulas as a consequence of endocarditis. This patient refused surgery until the progressive dyspnea was worsened by the endocarditis and the fistulas. At the time of surgery, his ventricular ejection fraction measured 47%, the ventricular chambers were enlarged, and the pulmonary to systemic flow ratio measured 2:1. He did well clinically after the VSD and fistulae repair.

Since it has been recognized that mitochondria are crucial not only for energy metabolism but also for other cellular functions, there has been a growing interest in cardiolipin, the specific phospholipid of mitochondrial membranes. Indeed, cardiolipin is a universal component of mitochondria in all eukaryotes. It has a unique dimeric structure comprised of two phosphatidic acid residues linked by a glycerol bridge, which gives rise to unique physicochemical properties. Cardiolipin plays an important role in the structural organization and the function of mitochondrial membranes. In this article, we review the literature on cardiolipin biology, focusing on the most important discoveries of the past decade. Specifically, we describe the formation, the migration, and the degradation of cardiolipin and we discuss how cardiolipin affects mitochondrial function. We also give an overview of the various phenotypes of cardiolipin deficiency in different organisms.

During development, the ventricular conduction system (VCS) arises from the trabecular or spongy myocardium. VCS and trabecular myocytes proliferate at a significantly slower rate than compact zone myocardial cells, establishing a transmural cell cycle gradient. The molecular determinants of VCS/trabecular myocyte cell cycle arrest are not known. Given the importance of pocket proteins (Rb, p107 and p130) in mediating G0/G1 arrest in many cell types, we examined the role of this gene family in regulating cell cycle exit of the trabecular myocardium and ventricular conduction system. Using a combinatorial knockout strategy, we found that graded loss of pocket proteins results in a spectrum of heart and lung defects. p107/p130 double knockout (dKO) hearts manifest dysregulated proliferation within the compact myocardium and trabecular bases, while the remaining trabecular region cell cycle exits normally. Consequently, dKO hearts exhibit defective cardiac compaction, septal hyperplasia and biventricular outflow tract obstruction, while the VCS appears relatively normal. Loss of all three pocket proteins (3KO) is necessary to completely disrupt the transmural cell cycle gradient. 3KO hearts exhibit massive overgrowth of the trabecular myocardium and ventricular conduction system, which leads to fetal heart failure and death. Hearts carrying a single pocket protein allele are able to maintain the transmural cell cycle gradient. These results demonstrate the exquisite sensitivity of trabecular and conduction myocytes to pocket protein function during ventricular chamber development.

Anomalous left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital anomaly present in approximately one in 300,000 live births. Here, we present a unique ALCAPA variant identified in a neonate. The left anterior descending artery originated posterolaterally on the main pulmonary artery, and the circumflex originated separately from the distal right pulmonary artery. doi: 10.1111/jocs.12079 (J Card Surg 2013;28:306-308).

MicroRNA cluster miR-17-92 has been implicated in cardiovascular development and function, yet its precise mechanisms of action in these contexts are uncertain. This study aimed to investigate the role of miR-17-92 in morphogenesis and function of cardiac and smooth muscle tissues. To do so, a mouse model of conditional overexpression of miR-17-92 in cardiac and smooth muscle tissues was generated. Extensive cardiac functional studies identified a dose-dependent induction of dilated, hypertrophic cardiomyopathy, and arrhythmia inducibility in transgenic animals, which correlated with premature mortality (98.3+/-42.5 d, P<0.0001). Expression analyses revealed the abundance of Pten transcript, a known miR-17-92 target, to be inversely correlated with miR-17-92 expression levels and heart size. In addition, we demonstrated through 3'-UTR luciferase assays and expression analyses that Connexin43 (Cx43) is a novel direct target of miR-19a/b and its expression is suppressed in transgenic hearts. Taken together, these data demonstrate that dysregulated expression of miR-17-92 during cardiovascular morphogenesis results in a lethal cardiomyopathy, possibly in part through direct repression of Pten and Cx43. This study highlights the importance of miR-17-92 in both normal and pathological functions of the heart, and provides a model that may serve as a useful platform to test novel antiarrhythmic therapeutics.-Danielson, L. S., Park, D. S., Rotllan, N., Chamorro-Jorganes, A., Guijarro, M. V., Fernandez-Hernando, C., Fishman, G. I., Phoon, C. K. L., Hernando, E. Cardiovascular dysregulation of miR-17-92 causes a lethal hypertrophic cardiomyopathy and arrhythmogenesis.