What Limits Cardiac Performance during Exercise in Normal Subjects and in Healthy Fontan Patients?

Exercise is an important determinant of health but is significantly reduced in the patient with a univentricular circulation. Normal exercise physiology mandates an increase in pulmonary artery pressures which places an increased work demand on the right ventricle (RV). In a biventricular circulation with pathological increases in pulmonary vascular resistance and/or reductions in RV function, exercise-induced augmentation of cardiac output is limited. Left ventricular preload reserve is dependent upon flow through the pulmonary circulation and this requires adequate RV performance. In the Fontan patient, the reasons for exercise intolerance are complex. In those patients with myocardial dysfunction or other pathologies of the circulatory components, it is likely that these abnormalities serve as a limitation to cardiac performance during exercise. However, in the healthy Fontan patient, it may be the absence of a sub-pulmonary pump which limits normal increases in pulmonary pressures, trans-pulmonary flow requirements and cardiac output. If so, performance will be exquisitely dependent on pulmonary vascular resistance. This provides a potential explanation as to why pulmonary vasodilators may improve exercise tolerance. As has recently been demonstrated, these agents may offer an important new treatment strategy which directly addresses the physiological limitations in the Fontan patient

Mitral Valve Prolapse

Mitral valve prolapse (MVP) is the most common valvular abnormality, affecting 2.4% of the population. Usually MVP is a benign disease and remains asymptomatic. The diagnosis of MVP is based on clinical presentation, physical examination and echocardiography. Some atypical symptoms that are not correlated with mitral valve function, are described as the MVP syndrome. Potential complications such as infective endocarditis, thromboembolic events, atrial and ventricular arrhythmias, and progressive mitral valve regurgitation may occur. Management should concentrate on adequate guidance of the patients, relief of symptoms and avoidance of complications

Rheologic genesis of discrete subvalvular aortic stenosis: A Doppler echocardiographic study

AbstractTo determine whether morphologic structures or abnormal flow patterns predispose to pathologic proliferation or subvalvular tissue, 26 patients (mean age 19.8 ± 10.3 years) were studied ≥6 months after operation for isolated discrete subvalvular aortic stenosis. The aortic root diameter and the mitral-aortic separation were measured with sector echocardiography. Flow patterns in the left ventricular outflow tract of these patients and control subjects were evaluated with a color flow mapping system optimized for the detection of turbulence.All control subjects had laminar flow throughout systole in the left ventricular outflow tract. By contrast, turbulence originating well below the site where the shelf had previously been resected was observed in 20 (77%) of the 26 patients. In 16 of these 20 patients turbulence was caused by a ridge, which in 13 patients could be identified as the offshoot of a ventricular band. In four patients the turbulence was caused by malalignment of the muscular and membranous septum, resulting in protrusion of the muscular septum into the outflow tract. Except for the latter four patients, the aortic root diameter was 84 ± 10% of values predicted by body surface area, with values in six patients falling below the third percentile (p < 0.01). The mitral-aortic separation was 9.7 ± 3.5 mm, values in 21 patients falling above the 97th percentile (p < 0.001).These data support the theory that discrete subvalvular aortic stenosis may be caused by a chronic flow disturbance, preferably in a small and long outflow tract. Left ventricular bands, if reaching the outflow tract, may be a factor. Because recurrence of subaortic stenosis is a frequent problem, these findings argue for careful echocardiographic and surgical exploration of the outflow tract well below the subvalvular stenosis to detect and resect structures that cause turbulence

Intermittent Brugada syndrome in an anorexic adolescent girl

AbstractWe report an anorexic adolescent girl with an intermittent Brugada syndrome. A 14-year-old anorexic girl with a body mass index (BMI) of 13.15kg/m2 was admitted in the acute state of the disease with an ST elevation in V1 and V2, suggestive of Brugada syndrome. After 1 month of re-feeding, a control electrograph (ECG) was normal, but after an 8-month follow-up control with a nearly normal BMI, the ECG was again suggestive of Brugada syndrome. A genetic analysis of the gene SNC5A established a genetic change (p Leu 1582 pro), which provides the final explanation for the Brugada syndrome. Every rhythm problem in the acute state or during the re-feeding procedure deserves a strict follow-up to distinguish iatrogenic from heritable rhythm problems.<Learning objective: (i) We report the first case of a patient with anorexia nervosa with an intermittent Brugada syndrome. (ii) Moderate hypothermia can decrease the depolarization of pacemaker cells and cause ST-segment changes. (iii) Every rhythm problem in the acute state or during the re-feeding procedure deserves a strict follow-up to distinguish iatrogenic from heritable rhythm problems. (iv) A genetic analysis can make the distinction and is necessary to give advice for the future lifestyle of the patient.

Collaboratively charting the gene-to-phenotype network of human congenital heart defects

Background How to efficiently integrate the daily practice of molecular biologists, geneticists, and clinicians with the emerging computational strategies from systems biology is still much of an open question. Description We built on the recent advances in Wiki-based technologies to develop a collaborative knowledge base and gene prioritization portal aimed at mapping genes and genomic regions, and untangling their relations with corresponding human phenotypes, congenital heart defects (CHDs). This portal is not only an evolving community repository of current knowledge on the genetic basis of CHDs, but also a collaborative environment for the study of candidate genes potentially implicated in CHDs - in particular by integrating recent strategies for the statistical prioritization of candidate genes. It thus serves and connects the broad community that is facing CHDs, ranging from the pediatric cardiologist and clinical geneticist to the basic investigator of cardiogenesis. Conclusions This study describes the first specialized portal to collaboratively annotate and analyze gene-phenotype networks. Of broad interest to the biological community, we argue that such portals will play a significant role in systems biology studies of numerous complex biological processes. CHDWiki is accessible at http://www.esat.kuleuven.be/~bioiuser/chdwikistatus: publishe

Downtown Waterville Feasibility Study Waterville, Maine

The Purpose and Need for this project is to: “Revitalize the Downtown to improve the aesthetics, support existing businesses and encourage economic growth, improve pedestrian and bicycle accommodations and provide adequate parking while maintaining vehicular capacity in the overall area.” Contributions and assistance in the completion of the study were provided by the City of Waterville, Colby College, the Maine Department of Transportation, and the General Public