Three hundred and twenty-six patients underwent CarboMedics valve implantation (CM) in the aortic (119 patients), mitral (148 patients) or aortic and mitral (59 patients) positions while 371 patients ...underwent St. Jude Medical valve implantation (SJ) in the aortic (113 patients), mitral (184 patient), or aortic and mitral (74 patients) positions at National Taiwan University Hospital from August 1991 through 1995. All patients received warfarin (Coumadin) anticoagulation with the target international normalized ratio around 1.5. The hospital mortality was 3.7% in the CM group and 4.3% in the SJ group. In the CM group at 5 years, the actuarial freedom from thromboembolism, valve thrombosis, and anticoagulant-related hemorrhage was 89.91 +/- 2.66%, 95. 23 +/- 1.50%, and 99.62 +/- 0.37%, respectively, and the actuarial survival rate was 90.4 +/- 1.6%. In the SJ group at 5 years, the actuarial freedom from thromboembolism, valve thrombosis, and anticoagulant-related hemorrhage was 94.79% +/- 1.70%, 98.80 +/- 0.72%, and 99.68 +/- 0.31%, respectively, and the actuarial survival rate was 91.3 +/- 1.7%. We therefore concluded that a similar survival rate was noted in the CM and SJ groups. With low dose anticoagulation, the complications of thromboembolism, valve thrombosis, and anticoagulant-related hemorrhage were low in the SJ group.
To evaluate correlates between electrocardiographic QT dispersion and coronary atherosclerosis in patients with aortic stenosis before aortic valve replacement, 39 consecutive patients >40 years old ...with symptomatic aortic stenosis and coronary diameter narrowing ≥50% measured by digital angiographic study were included. An additional matched group with insignificant coronary lesions (<50%) consisted of 39 patients for comparisons. Matching by age, sex heart rate and incidence of chest pain resulted in two comparable groups with identical baseline characteristics. Preoperative transthoracic echocardiography and electrocardiograms were performed in all subjects. QT dispersion was defined as the difference between maximal and minimal QT interval measurements occurring among any of the 12 leads on a standard electrocardiogram. No subject had fewer than nine measurable leads. There were no significant differences of risk factors of coronary artery disease between the two groups. From a conditional multivariate logistic regression analysis, independent predictors of development of coronary artery disease in aortic stenosis were only QTc dispersion (odds ratio=1.255,
P=0.01). A wide QTc dispersion (≥70 ins) correlated with the presence of angiographically significant coronary artery disease with a sensitivity and specificity of 72% and 79%. The positive accuracy of having significant coronary artery disease in the presence of QTc dispersion ≥70 ms was 78%. The negative predictive value was 74%. In conclusion, electrocardiographic QTc dispersion may provide important clinical information. A wide QTc dispersion in patients with aortic stenosis is associated with a high incidence of coronary artery disease. These findings warrant further investigation in a large trial.
Background— We have demonstrated that estrogen can reduce myocardial injury in ischemia-reperfusion via activation of ATP-sensitive potassium (K ATP ) channels. We sought to determine whether the ...protective effect of estrogen extends to epicardial coronary artery with attenuated vasoconstriction in patients after angioplasty by activation of such channels. Methods and Results— The study was designed to prospectively investigate 41 consecutive patients scheduled for elective coronary angioplasty. Pretreatment with estrogen limited myocardial ischemia during coronary occlusion and attenuated postangioplasty coronary vasoconstriction at the dilated and distal segments. An inhibitor of K ATP channels, glibenclamide, did not affect coronary vasomotor response, although it abolished the beneficial effect of estrogen on myocardial ischemia. Patients to whom estrogen was administered after the second balloon deflation experienced a similar magnitude of myocardial ischemia as controls but showed significantly attenuated vasoconstriction compared with controls ( P =0.0001). Endothelin-1 levels from the great cardiac vein rose significantly from 1.9±0.4 to 3.1±0.6 pg/mL ( P =0.001) 15 minutes after angioplasty in the control group; this was attenuated after estrogen was administered. Significant correlation was found between the changes in coronary vasomotion of the dilated segment and endothelin-1 levels ( r =0.65, P <0.0001). Conclusions— These results demonstrate that estrogen is protective against both myocardial ischemia and coronary vasoconstriction through different mechanisms. The myocardial effect of estrogen was abolished by glibenclamide, which suggests that the cardioprotective effect of estrogen may result from activation of K ATP channels. In contrast, estrogen-induced attenuated vasoconstriction is associated with an attenuated release of endothelin-1, independent of K ATP activation.
We investigated the effects of alternating transvalvular flow rate on Doppler-derived aortic valve resistance and valve area in asymptomatic patients with mechanical aortic valve replacement under ...dobutamine infusion. The Gorlin-derived aortic valve area and continuity equation-derived aortic valve area seem to be less flow dependent; valve resistance tends to be flow dependent.
Dengue fever (DF) is the most rapidly spreading mosquito-borne viral disease. Practical vaccines or specific therapeutics are still expected. Environmental factors and genetic factors affect the ...susceptibility of Dengue virus (DV) infection. Asthma is a common allergic disease, with house dust mites (HDMs) being the most important allergens. Asthmatic patients are susceptible to several microorganism infections.
A nationwide population-based cohort analysis was designed to assess whether to determine whether asthma can be a risk factor for DF.
Unexpectedly, our data from a nationwide population-based cohort revealed asthmatic patients are at a decreased risk of DF. Compared to patients without asthma, the hazard ratio (HR) for DF in patients with asthma was 0.166 (95% CI: 0.118–0.233) after adjustment for possible confounding factors. In the age stratification, the adjusted HR for DF in young adult patients with asthma was 0.063. Dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) of dendritic cells (DCs) is an important entry for DV. Through another in vitro experiment, we found that HDM can diminish surface expression of DC-SIGN in monocyte-derived DCs and further decrease the cellular entry of DV.
Decreased DC-SIGN expression in DCs of allergic asthmatic patient may be one of many factors for them to be protected against DF. This could implicate the potential for DC-SIGN modulation as a candidate target for designing therapeutic strategies for DF.
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In this research, we propose recurrent neural networks (RNNs) to build a relationship between rainfalls and water level patterns of an urban sewerage system based on historical torrential rain/storm ...events. The RNN allows signals to propagate in both forward and backward directions, which offers the network dynamic memories. Besides, the information at the current time-step with a feedback operation can yield a time-delay unit that provides internal input information at the next time-step to effectively deal with time-varying systems. The RNN is implemented at both gauged and ungauged sites for 5-, 10-, 15-, and 20-min-ahead water level predictions. The results show that the RNN is capable of learning the nonlinear sewerage system and producing satisfactory predictions at the gauged sites. Concerning the ungauged sites, there are no historical data of water level to support prediction. In order to overcome such problem, a set of synthetic data, generated from a storm water management model (SWMM) under cautious verification process of applicability based on the data from nearby gauging stations, are introduced as the learning target to the training procedure of the RNN and moreover evaluating the performance of the RNN at the ungauged sites. The results demonstrate that the potential role of the SWMM coupled with nearby rainfall and water level information can be of great use in enhancing the capability of the RNN at the ungauged sites. Hence we can conclude that the RNN is an effective and suitable model for successfully predicting the water levels at both gauged and ungauged sites in urban sewerage systems.
To evaluate the effect of mitral valve repair on the regression of left ventricular mass, we studied 50 consecutive patients with severe, pure mitral regurgitation undergoing mitral valve repair. ...Two-dimensional echocardiograms were recorded a mean 2.5 ± 2.0 weeks before and 6.5 ± 2.5 months after valve operation. Postoperative significant mitral regurgitation was present in 3 patients. After mitral valve repair there were significant decreases in left ventricular end-diastolic volume index (133 ± 39 mL/m
2 to 79 ± 35 mL/m
2;
p < 0.001), end-systolic volume index (44 ± 26 mL/m
2 to 30 ± 26 mL/m
2;
p < 0.001), stroke volume index (89 ± 29 mL/m
2 to 49 ± 19 mL/m
2;
p < 0.001), and mass index (211 ± 82 g/m
2 to 134 ± 52 g/m
2;
p < 0.001). There also were significant decreases in left atrial dimension (47 ± 9 mm to 38 ± 9 mm;
p < 0.001), left ventricular end-diastolic dimension (61 ± 8 mm to 48 ± 7 mm;
p < 0.001), and end-systolic dimension (39 ± 8 mm to 32 ± 7 mm;
p < 0.001). Left ventricular ejection fraction decreased slightly from 0.69 ± 0.12 to 0.64 ± 0.12;
p < 0.01) after repair. Thus, correction of pure mitral regurgitation leads to reduction of the cardiac chamber size and left ventricular volumes as well as regression of the left ventricular mass.
OBJECTIVES
We investigated the gene expression of calcium-handling genes including L-type calcium channel, sarcoplasmic reticular calcium adenosine triphosphatase (Ca2+-ATPase), ryanodine receptor, ...calsequestrin and phospholamban in human atrial fibrillation.
BACKGROUND
Recent studies have demonstrated that atrial electrical remodeling in atrial fibrillation is associated with intracellular calcium overload. However, the changes of calcium-handling proteins remain unclear.
METHODS
A total of 34 patients undergoing open heart surgery were included. Atrial tissue was obtained from the right atrial free wall, right atrial appendage, left atrial free wall and left atrial appendage, respectively. The messenger ribonucleic acid (mRNA) amount of the genes was measured by reverse transcription–polymerase chain reaction and normalized to the mRNA levels of glyceraldehyde 3-phosphate dehydrogenase.
RESULTS
The mRNA of L-type calcium channel and of Ca2+-ATPase was significantly decreased in patients with persistent atrial fibrillation for more than 3 months (0.36 ± 0.26 vs. 0.90 ± 0.88 for L-type calcium channel; 0.69 ± 0.42 vs. 1.21 ± 0.68 for Ca2+-ATPase; both p < 0.05, all data in arbitrary unit). We further demonstrated that there was no spatial dispersion of the gene expression among the four atrial tissue sampling sites. Age, gender and underlying cardiac disease had no significant effects on the gene expression. In contrast, the mRNA levels of ryanodine receptor, calsequestrin and phospholamban showed no significant change in atrial fibrillation.
CONCLUSIONS
L-type calcium channel and the sarcoplasmic reticular Ca2+-ATPase gene were down-regulated in atrial fibrillation. These changes may be a consequence of, as well as a contributory factor for, atrial fibrillation.
Myocardial ATP‐sensitive potassium (KATP) channels have been implicated in left ventricular (LV) remodeling by inhibition of 70‐kDa S6 (p70S6) kinase. We assessed whether KATP channel agonists exert ...beneficial effect on the structural, functional, and molecular features of LV remodeling in infarcted rats. After ligation of the anterior descending artery, male Wistar rats were randomized to either vehicle, agonists of KATP channels nicorandil and pinacidil, an antagonist of KATP channels glibenclamide, or a combination of nicorandil and glibenclamide or pinacidil and glibenclamide for 4 weeks. Significant LV hypertrophy was detected by increased myocyte size isolated by enzymatic dissociation after infarction. Rats in the nicorandil‐ and pinacidil‐treated groups significantly attenuated LV hypertrophy, as compared with the vehicle‐treated group. LV shortening fraction was significantly higher in the nicorandil‐ or pinacidil‐treated groups compared with the vehicle‐treated group. Increased expression of p70S6 kinase mRNA was confirmed by RT‐PCR, consistent with the results of immunohistochemistry and Western blot for the phosphorylation of p70S6 kinase. The beneficial effects of nicorandil and pinacidil were abolished by administering glibenclamide. Thus, activation of KATP channels can attenuate LV remodeling through a S6 kinase‐dependent pathway after infarction.
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