Impact and Predictors of Noncircular Left Ventricular Outflow Tract Shapes on Estimating Aortic Stenosis Severity by Means of Continuity Equations

Determining aortic stenosis (AS) severity is clinically important. Calculating aortic valve (AV) area by means of the continuity equation assumes a circular left ventricular outflow tract (LVOT). The full impact of this assumption in calculating AV area is unknown. Predictors of noncircular LVOT shape in patients with AS are undefined.In 109 adult patients with AS who underwent multiplanar transesophageal echocardiography, we calculated AV area by means of the standard continuity method and by a modified method involving planimetric LVOT area.We found 54 circular, 37 horizontal-oval, 8 vertical-oval, and 10 irregular LVOTs. Area derived by direct planimetry correlated better with the modified than the standard continuity method (r=0.89 vs r=0.85; both P=0.0001). Valve areas of patients with mild, moderate, or severe AS by planimetry were more often mischaracterized with use of the standard than modified method (29 vs 18; P <0.0001). Horizontal-oval AV area derived by planimetry (1.28 ± 0.55 cm²) was underestimated by the standard method (1.05 ± 0.47 cm²; P=0.001), but not by the modified method. Congenital AV morphology and low cardiac index were the only multivariate predictors of horizontal-oval shape. Low cardiac index was the only predictor of noncircular shape.More than half our patients with AS had noncircular LVOTs. Using the modified method reduces mischaracterizations of AS severity. Congenital AV morphology and low cardiac index predict horizontal-oval or noncircular shape. These data suggest the value of direct LVOT measurement to calculate AS severity in patients who have congenital AV or a low cardiac index.     

Vitamin D,Cardiovascular System,and Longevity of Hemodialysis Patients

Abstract: The risk of cardiovascular death is high in hemodialysis (HD) patients, and thickening, stiffening and calcification of the arterial wall have been shown as its predictive factors. Activated vitamin D preparations are used for the treatment of secondary hyperparathyroidism in HD patients, but as they increase serum phosphate and calcium concentrations, there is a concern that they promote vascular calcification and, consequently, exacerbate the outcomes. In this article, the effects of vitamin D therapy on survival, cardiac function, arteriosclerosis, immunity, and inflammation are evaluated by reviewing the literature. In HD patients, the risk of death (particularly cardiovascular death) is significantly lower in those treated than in those not treated with vitamin D. Moreover, activated vitamin D improves cardiac function and alleviates cardiac hypertrophy in HD patients. Experimental data in cultured macrophages, vascular smooth muscle cells, and vascular endothelial cells suggest that it has antiatherosclerotic effects. In vivo, the administration of vitamin D improves immune functions and normalizes inflammatory reactions. In HD patients, vascular calcification is related to the dose of calcium carbonate, but its relationship with the administration of vitamin D is not significant. These observations suggest that, contrary to the general concerns, activated vitamin D exerts favorable effects on the cardiovascular system in HD patients as long as it is used in appropriate clinical doses.     

Ross手术的临床应用现状

Ross手术自1967年应用于临床以来，已被用于各种原因引起的主动脉瓣狭窄、左心室流出道梗阻和二尖瓣病变。Ross手术经历了诸如根部置换、圆筒形包埋技术、瓣环缩小技术、Ross—Konno手术和自体肺动脉瓣二尖瓣置换术（Ross—Kabbani手术或RossⅡ手术）。由于自体肺动脉瓣有不需抗凝、大小适宜、能存活、生长和长期耐久的特性，并具有良好的血流动力学表现和对细菌性心内膜炎有抵抗力的优点，尤其适用于妊娠期妇女、儿童和青少年。现就Ross手术的外科技术、手术指征、选择标准、外科处理主动脉瓣狭窄、左心室流出道梗阻和二尖瓣病变的临床应用进展和效果进行综述。     

Left ventricular mass regression following aortic valve replacement with mechanical valves

Objective The degree of Left Ventricular Mass Index (LVMI) regression following aortic valve replacement correlates with long-term survival. This study aims to assess the extent of LVMI regression at 3 months following aortic valve replacement (AVR) with different types and sizes of mechanical valves in rheumatic aortic valve disease. Methods The LVMI regression was studied in 34 consecutive patients, undergoing elective AVR for rheumatic aortic stenosis and/or regurgitation. They were grouped in A and B, matched in age, body surface area and pre-operative LVMI, receiving respectively a tilting disc and a bileaflet mechanical valve. The LVMI was calculated by M-mode echocardiography using the Devereux' formula pre-operatively and three months post-operatively. The trend of LVMI reduction was compared between the two groups and amongst the patients with stenotic, regurgitant and mixed aortic valve, pathologies; and receiving different sizes of valves. Results The mean preoperative LVMI was 199g±79.5 g/m². At three months post aortic valve replacement, the mean LVMI was 130g±49.0 g/m². There was a significant reduction of LVMI post-operatively (p=0.001) at three months follow-up. The extent of LVMI regression following surgery amongst the groups A and B did not vary significantly (p=0.92). The extent of LVMI regression did not vary significantly in patients with different aortic valve pathology nor with different sizes of the valves implanted. Conclusions There is a significant early LVMI regression following aortic valve replacement in rheumatic aortic valve disease. The type and the size of the mechanical prosthesis or the rheumatic pathology do not appear to influence this regression.     

From Innumeracy to Insight: The Uncertainty of Help versus Harm in Treatment of Asymptomatic Aortic Aneurysms

There is insufficient evidence that the surgical treatment of asymptomatic infrarenal aneurysms > 5.5 cm. is beneficial to patients. This is the result of serious complications of aneurysm surgery and the dearth of information from randomized trials. Based on evidence from the literature we defined scenarios and translated data into natural frequency trees to improve understanding of the uncertainty of help versus harm due to treatment of aneurysms. Our analysis shows that the majority of patients can expect little on longevity from surgery while they are at risk of dying from surgery or suffering from serious morbidity. We conclude that, as long as uncertainty persist, patients should be treated in hospitals that can show very low surgical mortality and major morbidity rates. To further resolve the problem of uncertainty randomized trials for larger aneurysms should be performed. Important issues to discuss are the lower and upper limits of the diameter of the aneurysms and the age and risk profiles of the patients to be included in such trials.     

Pediatric valve replacement, 15 years experience in Oman

Background Despite improving surgical techniques, treatment of heart valve disease in children remains controversial. Somatic growth and adequate anticoagulation are of concern when children undergo valve replacement. We conducted this study to evaluate the performance of valves in this age group. Methods 42 children under the age of 13 years who underwent valve replacement were included in this study. Totally, 50 valves were implanted in 42 patients: 48 were mechanical prostheses, two were bioprosthetic both in pulmonary position. 37 (74%) valves were implanted in mitral position, 10 (20%) in aortic position, 1 (2%) in tricuspid position and 2 (4%) in pulmonary position. Preoperatively, 14 (33,3%) patients were in New York Heart Association (NYHA) class IV, while 27 (64.2%) were in NYHA class III. Results There were 2 (4.7%) hospital deaths and 2 (4.7%) late deaths while 2 (4.7%) patients were lost to follow up. The mean follow up period was 9.4 yrs. 35 (83.3%) patients are in NYHA Class I and free of all medications except warfarin. 3 (7.1%) patients have undergone 5 successful pregnancies. The median INR was 2.23. Major thrombo-embolic episode occurred in 1 (2.3%) patient. Conclusions In view of the problems of sizing, anticoagulation and need for re-operation at an early age, there is a reluctance to replace valves in children. This study shows that despite these problems, valve replacement can be undertaken safely and successfully in children, when repair has failed or not technically feasible.     

Cardiovascular calcification in end-stage renal disease.

Cardiovascular diseases are common in patients with end-stage renal disease (ESRD) and cardiovascular morbidity and mortality among dialysis patients are substantially higher than in the general population. The reasons for this high incidence are multiple. They include traditional factors such as hypertension, diabetes, dyslipidaemia, sodium overload, and elevated homocysteine levels as well as disturbances of mineral metabolism, specifically abnormalities in phosphorus and calcium homeostasis. This review will describe the specific cardiovascular complications related to calcifications in ESRD, the implications of the abnormalities of mineral metabolism in its pathogenesis and the current imaging techniques available for the detection of cardiovascular calcifications. Excess of calcium load contributes to the development of cardiac calcifications; therefore, alternative strategies to diminish exogenous calcium load should be considered in patients with ESRD.