Measurements of MIMO-UWB indoor channel

Channel measurements are reported for an emulated indoor MIMO-UWB system. The emulated system represents a ceiling-mounted access-point with two identical UWB, horizontally-polarized, antennas and a portable terminal for desk-top use with between two and four (also identical) horizontally-polarized antennas. The maximum MIMO-UWB channel capacities of the measured channels are calculated and the statistics of these capacities are presented. The channel capacity advantage of MIMO-UWB over SISO-UWB is also presented

Normal coronary flow reserve in patients with mitral valve prolapse, a positive exercise test and normal coronary arteries

We studied 12 patients (eight females and four males), ages 30-46 years, with echocardiographically documented mitral valve prolapse and clinical suspicion of coronary artery disease, based on a history of chest pain (five patients), angina-like pain (three patients), a positive exercise stress electrocardiogram (12 patients) and a focally positive thallium-201 stress perfusion scan (three patients), who were referred for cardiac catheterization and found to have normal coronary arteries. Ten patients without evidence of heart disease served as controls. In all mitral valve prolapse patients, coronary flow velocity reserve was determined successively in the left anterior descending, left circumflex and right coronary arteries as the ratio of the maximum (after intracoronary papaverine) to the resting mean coronary flow velocity. Coronary flow reserve valued were fairly similar in the mitral valve prolapse and control patients; all 12 mitral valve prolapse patients had normal coronary flow reserve (greater than or equal to 3.5) in all three coronary arteries with no significant differences among the arteries tested. Mean values +/- 1 standard deviation of the coronary flow reserve (mitral valve prolapse vs control patients) were 4.7 +/- 0.5 vs 4.6 +/- 0.6 for the left anterior descending, 4.6 +/- 0.4 vs 4.6 +/- 0.3 for the left circumflex and 4.5 +/- 0.4 vs 4.4 +/- 0.5 for the right coronary artery (all P = non-significant). The subsets of mitral valve prolapse patients with different clinical ‘ischaemic’ manifestations were similar in terms of the calculated coronary flow reserve in all three major epicardial coronary arteries. In conclusion, this study demonstrated that an inadequate regional coronary flow reserve does not account for the clinical manifestations of myocardial ischaemia and positive exercise tests in patients with mitral valve prolapse and normal coronary arteries

SEX-DIFFERENCES IN THE ANATOMY OF CORONARY-ARTERY DISEASE

In a prospective study, the extent and severity of coronary artery disease (CAD) as well as the location of coronary stenoses were studied comparatively, in relation to age and sex, in 192 consecutive women vs 543 selected men, who all underwent coronary angiography during the same time period, and who were found to have significant CAD. Overall, the age of women (59 +/- 8 years) was higher than that of men (55 +/- 8 years), p < 0.001. Also, the prevalence of smoking was higher in men (81% vs 31%, p = 0.0000) and that of diabetes mellitus in women (29% vs 12%, p = 4 x 10(-6)). In addition, women over 50 years old had a higher incidence of hypertension (51% vs 32%, p = 6 x 10(-5)). Although in both sexes the prevalence of multivessel CAD increased with age, the prevalence of one-vessel CAD was significantly more and that of three-vessel CAD significantly less common in women than in men, both overall (35% vs 16%, p = 4 x 10(-8) and 36% vs 54%, p = 2 x 10(-5), respectively) and in all age subgroups. However, the location of coronary stenoses did not show important differences between men and women with the left anterior descending being the most frequently involved artery. Furthermore, the calculated Gensini index, which reflects cumulatively the extent, severity and location of coronary stenoses, was significantly higher in men (59.2 +/- 34.6 vs 52.2 +/- 36.2, p = 0.03), implying more severe and extensive CAD. The prevalence of angiographically evident collateral circulation also increased with age and was significantly higher in men than in women (58% vs 48%, p = 0.025). The global left ventricular fraction was not different between male and female patients in the study 48.1 +/- 14 vs 46.8 +/- 14.5%). It is concluded that among patients who develop CAD there are still important age- and sex-related differences in the patterns of coronary anatomy which could be helpful in the clinical evaluation and management of patients with coronary disease, especially women

Target heart rate to determine the normal value of coronary flow reserve during dobutamine stress echocardiography

<p>Abstract</p> <p>Background</p> <p>The determination of coronary flow reserve (CFR) is an essential concept at the moment of decision-making in ischemic heart disease. There are several direct and indirect tests to evaluate this parameter. In this sense, dobutamine stress echocardiography is one of the pharmacological method most commonly used worldwide. It has been previously demonstrated that CFR can be determined by this technique. Despite our wide experience with dobutamine stress echocardiography, we ignored the necessary heart rate to consider sufficient the test for the analysis of CFR. For this reason, our main goal was to determine the velocity of coronary flow in each stage of dobutamine stress echocardiography and the heart rate value necessary to double the baseline values of coronary flow velocity in the territory of the left anterior descending (LAD) coronary artery.</p> <p>Methods</p> <p>A total of 33 consecutive patients were analyzed. The patients included had low risk for coronary artery disease. All the participants underwent dobutamine stress echocardiography and coronary artery flow velocity was evaluated in the distal segment of LAD coronary artery using transthoracic color-Doppler echocardiography.</p> <p>Results</p> <p>The feasibility of determining CFR in the territory of the LAD during dobutamine stress echocardiography was high: 31/33 patients (94%). Mean CFR was 2.67 at de end of dobutamine test.</p> <p>There was an excellent concordance between delta HR (difference between baseline HR and maximum HR) and the increase in the CFR (correlation coefficient 0.84). In this sense, we found that when HR increased by 50 beats, CFR was ≥ 2 (CI 93-99.2%). In addition, 96.4% of patients reached a CFR ≥ 2 (IC 91.1 - 99%) at 75% of their predicted maximum heart rate.</p> <p>Conclusions</p> <p>We found that the feasibility of dobutamine stress echocardiography to determine CFR in the territory of the LAD coronary artery was high. In this study, it was necessary to achieve a difference of 50 bpm from baseline HR or at least 75% of the maximum predicted heart rate to consider sufficient the test for the analysis of CFR.</p

Dual antiplatelet therapy duration after coronary stenting in clinical practice: results of an EAPCI survey

Aims: Our aim was to report on a survey initiated by the EuropeanAssociation of Percutaneous Cardiovascular Interventions (EAPCI) concerning opinion on the evidence relating to dual antiplatelet therapy (DAPT) duration after coronary stenting.Methods and results: Results from three randomised clinical trials were scheduled to be presented at the American Heart Association Scientific Sessions 2014 (ARIA 2014). A web-based survey was distributed to all individuals registered in the EuroIntervention mailing list (n=15,200) both before and after ARIA 2014. A total of 1,134 physicians responded to the first (i.e., before AHA 2014) and 542 to the second (i.e., after ARIA 2014) survey. The majority of respondents interpreted trial results consistent with a substantial equipoise regarding the benefits and risks of an extended versus a standard DAPT strategy. Two respondents out of ten believed extended DAFT should be implemented in selected patients. After ARIA 2014, 46.1% of participants expressed uncertainty about the available evidence on DAFT duration, and 40.0% the need for clinical guidance.Conclusions: This EAPCI survey highlights considerable uncertainty within the medical community with regard to the optimal duration of DAFT after coronary stenting in the light of recent reported trial results. Updated recommendations for practising physicians to guide treatment decisions in routine clinical practice should be provided by international societies