Myocardial adaptations in aortic valve disease.

Injections of human chorionic gonadotropin (HCG) have been claimed to aid in weight reduction by reducing hunger, and affecting mood as well as aiding in localized (spot) reduction. We have tested these claims in a double-blind randomized trial using injections of HCG or placebo. Weight loss was identical between the two groups, and there was no evidence for differential effects on hunger, mood or localized body measurements. Placebo injections, therefore, appear to be as effective as HCG in the treatment of obesity.     

Hyperlipidaemia and aortic valve disease

PURPOSE OF REVIEW: Degenerative aortic valve stenosis is a common disease in the elderly, and traditional risk factors for atherosclerotic disease including hyperlipidaemia have been associated with the condition in several studies. This review addresses the role of the various risk factors and the potential for intervention. RECENT FINDINGS: The association of lipid abnormalities such as high lipoprotein(a) levels and the presence of the apolipoprotein E4 allele with aortic stenosis, as well as the presence of several inflammatory markers both in plasma and in surgically excised valves, suggest that the stenotic process is driven by many of the same factors behind atherosclerosis. The aortic valves of animals fed a cholesterol-rich diet exhibit many characteristics in common with the early stages of aortic stenosis. This opens up the potential of retarding the process through intervention strategies. SUMMARY: Hyperlipidaemia is associated with degenerative aortic valve stenosis, and the disease resembles the inflammatory process of atherosclerosis. Randomized controlled clinical trials will be needed to demonstrate the role of lipid intervention in patients with this condition.     

Surgical management of chronic occlusive disease of the aortic arch vessels and vertebral arteries.

Occlusive disease of the aortic arch vessels is relatively rare and often missed initially. Of 41 patients treated surgically for this condition over a 10-year period 38 had arteriosclerotic lesions, 2 had symptoms secondary to vasculitis (Takayasu''s arteritis) and 1 had a radiation injury to a subclavian artery. In 22 cases the left subclavian artery was involved; the right subclavian and innominate arteries were the next most commonly affected. Only four vertebral stenoses were treated. Most patients presented with a combination of arm and hindbrain ischemia that was shown radiologically to be associated with a subclavian steal syndrome, but in some only isolated arm symptoms or severe vertigo alone was experienced. There was a difference in blood pressure between the arms of at least 20 mm Hg in 88% of the patients. The treatment for 28 patients was creation of a carotid-subclavian bypass, for 6 the placement of a bypass graft from the ascending aorta to the subclavian or carotid artery or both, for a 3 a subclavian endarterectomy and for 4 vertebral angioplasty. There were no operative deaths, and 90% of the grafts were patent 1 to 72 months later. however, only 30 (73%) of the patients were asymptomatic and 9 (22%) had improved.     

Mechano-potential etiologies of aortic valve disease

Aortic valve leaflets experience varying applied loads during the cardiac cycle. These varying loads act on both cell types of the leaflets, endothelial and interstitial cells, and cause molecular signaling events that are required for repairing the leaflet tissue, which is continually damaged from the applied loads. However, with increasing age, this reparative mechanism appears to go awry as valve interstitial cells continue to remain in their ‘remodeling’ phenotype and subsequently cause the tissue to become stiff, which results in heart valve disease. The etiology of this disease remains elusive; however, multiple clues are beginning to coalesce and mechanical cues are turning out to be large predicators of cellular function in the aortic valve leaflets, when compared to the cells from the pulmonary valve leaflets, which are under a significantly less demanding mechanical loading regime. Finally, this paper discusses the mechanical environment of the constitutive cell populations, mechanobiological processes that are currently unclear, and a mechano-potential etiology of aortic disease will be presented.     

Impact of calcific aortic valve disease on valve mechanics

Biomechanics and Modeling in Mechanobiology - The aortic valve is a highly dynamic structure characterized by a transvalvular flow that is unsteady, pulsatile, and characterized by episodes of...     

Huntington's chorea and genetic counseling. Natural history of the disease

Editor introduction for the meeting theme. The lecturer briefly describes how the HD genes were brought from the Old World to the New World and resumes the data of the current research in histopathology and physiology.     

Timing of valve replacement in chronic aortic regurgitation. A pathophysiological approach

Timing of valve replacement (AVR) in chronic aortic regurgitation remains a difficult problem in clinical practice. When the disease takes a favorable natural course, this may be attributed to excellent compensatory mechanisms - especially an increase in left ventricular end-diastolic volume (LVEDV) in relation to regurgitant volume (RV) - whereas a rapid clinical and hemodynamic deterioration may usually be ascribed to a vicious circle consisting in a marked increase in afterload leading to an increase in LVEDV and so on. 54 patients with aortic regurgitation underwent pre- and postoperative as well as long-term follow-up radionuclide ventriculographic (RNV) studies in order to determine LVEDV and RV and to measure left ventricular ejection fraction (LVEF). These measures were expected to provide information on 'physiologic' LVEDV elevation in relation to RV. Our results indicate that if LVEDV exceeds 300-400 ml there may be an increase in afterload for LV. Factors counteracting this increased afterload (LV hypertrophy, increased diastolic stretching) will eventually preserve LVEF and keep LVEDV/RV within the normal range, but are accompanied by an elevation of LV filling pressure leading to dyspnea on exertion. With an LVEDV exceeding 400-500 ml these factors generally cannot prevent the initiation of the above mentioned vicious circle. Hence, in these severely symptomatic cases LVEDV/RV exceeds the normal range and LVEF becomes markedly depressed. An unfavorable postoperative result must be expected in these patients, while the postoperative result will be good in cases with an LVEDV/RV within the normal range. Hence, we conclude that AVR should ideally be performed in those patients with an EDV exceeding 300 ml, who still have an LVEDV/RV within the normal range, but who show clinical symptoms and/or an only moderately depressed LVEF, indicating that the limits of the compensatory mechanism are reached. The indications for AVR in other conditions characterized by the clinical status, the level of the LVEDV and LVEDV/RV are discussed.     

Computational assessment of bicuspid aortic valve wall-shear stress: implications for calcific aortic valve disease

The bicuspid aortic valve (BAV) is associated with a high prevalence of calcific aortic valve disease (CAVD). Although abnormal hemodynamics has been proposed as a potential pathogenic contributor, the native BAV hemodynamic stresses remain largely unknown. Fluid-structure interaction models were designed to quantify the regional BAV leaflet wall-shear stress over the course of CAVD. Systolic flow and leaflet dynamics were computed in two-dimensional tricuspid aortic valve (TAV) and type-1 BAV geometries with different degree of asymmetry (10 and 16% eccentricity) using an arbitrary Lagrangian–Eulerian approach. Valvular performance and regional leaflet wallshear stress were quantified in terms of valve effective orifice area (EOA), oscillatory shear index (OSI) and temporal shear magnitude (TSM). The dependence of those characteristics on the degree of leaflet calcification was also investigated. The models predicted an average reduction of 49% in BAV peak-systolic EOA relative to the TAV. Regardless of the anatomy, the leaflet wall-shear stress was side-specific and characterized by high magnitude and pulsatility on the ventricularis and low magnitude and oscillations on the fibrosa. While the TAV and non-coronary BAV leaflets shared similar shear stress characteristics, the base of the fused BAV leaflet fibrosa exhibited strong abnormalities, which were modulated by the degree of calcification (6-fold, 10-fold and 16-fold TSM increase in the normal, mildly and severely calcified BAV, respectively, relative to the normal TAV). This study reveals the existence of major differences in wall-shear stress pulsatility and magnitude on TAV and BAV leaflets. Given the ability of abnormal fluid shear stress to trigger valvular inflammation, the results support the existence of a mechano-etiology of CAVD in the BAV.     

Catheter-based management of aortic valve regurgitation in experimental cardiology

Non-surgical management of aortic valve disease has been given considerable attention. Several recent publications have already reported its use in clinical practice. The main issue is to get an understanding of the pathophysiological processes and, most importantly, extensive experimental activity. In addition to testing various animal models, technical and material aspects are also being intensively investigated. It is not clear yet whether the durability and applicability of this promising development will be comparable with the standard of current cardiac surgery. Nonetheless, even the use of some models as a temporary approach helping to improve the circulatory status, not allowing safe surgery, is certainly justified. At any rate, a new stage of research and clinical application has been set off. However, experimental background continues to be simply indispensable. The paper is a short review of the issue.