Georgios Spanos

Chronotropic incompetence and its relation to exercise intolerance in hypertrophic cardiomyopathy.

BACKGROUND Diminished functional capacity is common in hypertrophic cardiomyopathy (HCM), although the underlying mechanisms are complicated. We studied the prevalence of chronotropic incompetence and its relation to exercise intolerance in patients with HCM. METHODS Cardiopulmonary exercise testing was performed in 68 patients with HCM (age 44.8 ± 14.6 years, 45 males). Chronotropic incompetence was defined by chronotropic index (heart rate reserve)/(220-age-resting heart rate) and exercise capacity was assessed by peak oxygen consumption (peak Vo(2)). RESULTS Chronotropic incompetence was present in 50% of the patients and was associated with higher NYHA class, history of atrial fibrillation, higher fibrosis burden on cardiac MRI, and treatment with β-blockers, amiodarone and warfarin. On univariate analysis, male gender, age, NYHA class, maximal wall thickness, left atrial diameter, peak early diastolic myocardial velocity of the lateral mitral annulus, history of atrial fibrillation, presence of left ventricular outflow tract obstruction (LVOTO) at rest, and treatment with beta-blockers were related to peak Vo(2). Peak heart rate during exercise, heart rate reserve, chronotropic index, and peak systolic blood pressure were also related to peak Vo(2). On multivariate analysis male gender, atrial fibrillation, presence of LVOTO and heart rate reserve were independent predictors of exercise capacity (R(2) = 76.7%). A cutoff of 62 bpm for the heart rate reserve showed a negative predictive value of 100% in predicting patients with a peak Vo(2) <80%. CONCLUSIONS Blunted heart rate response to exercise is common in HCM and represents an important determinant of exercise capacity.

WIVSS: a new methodology for scoring information systems vulnerabilities

Vulnerabilities of information systems constitute an ever-increasing problem that IT security management must solve. As the number of vulnerabilities is growing exponentially, their ranking and prioritization is a crucial task for organizations and researchers that are involved with the security of computer systems. The open standard to score and rank the vulnerabilities is the Common Vulnerability Scoring System (CVSS) while the focus of this research is to investigate ways to improve it by achieving higher diversity of values and better accuracy. In this paper it is introduced a new vulnerability scoring system, called WIVSS (Weighted Impact Vulnerability Scoring System). The methodology uses a different approach to score vulnerabilities, depending on the different impact of vulnerabilities characteristics. The methodology WIVSS is applied to the most recent 9455 vulnerabilities and the results show improvement in comparison with CVSS.

The impact of information security events to the stock market

Information security is a highly critical aspect of information systems. Although the literature regarding security assurance is vast, the research on economic consequences of security incidents is quite limited. The purpose of this systematic review is to search, collect and classify event studies related to information security impact on stock prices. In total, 37 related papers conducting 45 studies were found by the systematic search of bibliographic sources. The majority (75.6%) of these studies report statistical significance of the impact of security events to the stock prices of firms.

Impact Metrics of Security Vulnerabilities: Analysis and Weighing

ABSTRACT The number of vulnerabilities discovered and reported during the recent decades is enormous, making an improved ranking and prioritization of vulnerabilities’ severity a major issue for information technology (IT) management. Although several methodologies for ranking and scoring vulnerabilities have been proposed, the Common Vulnerability Scoring System (CVSS) is the open standard with wide acceptance from the information security community. Recently, the Weighted Impact Vulnerability Scoring System (WIVSS) has been proposed as an alternative scoring methodology, which assigns different weights to impact factors of vulnerability in order to achieve higher diversity of values and thus improvement in flexibility of ranking in comparison to CVSS. The purpose of this paper is to expand the idea of WIVSS by defining the sets of weights which provide higher diversity of values. For this reason, an algorithm that finds all the possible combinations of optimal weights within a specified range and under certain constrains is presented. The algorithm results in 14 different combinations of impact weights that are applied to a sample of 20,496 vulnerabilities and statistically analyzed for associations among impact factors. The results suggest that one specific combination of impact weights can achieve highest diversity of values.

Hypertrophic cardiomyopathy with midventricular obstruction and apical aneurysm formation in a single family: case report

BackgroundHypertrophic cardiomyopathy (HCM) is an extremely heterogeneous disease. An under recognized and very often missed subgroup within this broad spectrum concerns patients with left ventricular (LV) apical aneurysms in the absence of coronary artery disease.Case presentationWe describe a case of HCM with midventricular obstruction and apical aneurysm formation in 3 patients coming from a single family. This HCM pattern was detected by 2D-echocardiography and confirmed by cardiac magnetic resonance imaging. A cardioverter defibrillator was implanted in one of the patients because of non-sustained ventricular tachycardia detected in 24-h Holter monitoring and an abrupt drop in systolic blood pressure during maximal exercise test. The defibrillator activated 8 months after implantation by suppression of a ventricular tachycardia providing anti-tachycardia pacing. The patient died due to refractory heart failure 2 years after initial evaluation. The rest of the patients are stable after a 2.5-y follow-up period.ConclusionThe detection of apical aneurysm by echocardiography in HCM patients may be complicated. Ventricular tachycardia arising from the scarred aneurysm wall may often occur predisposing to sudden death.

Associating the Severity of Vulnerabilities with their Description

Software vulnerabilities constitute a major problem for today’s world, which relies more than ever to technological achievements. The characterization of vulnerabilities’ severity is an issue of major importance in order to address them and extensively study their impact on information systems. That is why scoring systems have been developed for the ranking of vulnerabilities’ severity. However, the severity scores are based on technical information and are calculated by combining experts’ assessments. The motivation for the study conducted in this paper was the question of whether the severity of vulnerabilities is directly related to their description. Hence, the associations of severity scores and individual characteristics with vulnerability descriptions’ terms were studied using Text Mining, Principal Components and correlation analysis techniques, applied to all vulnerabilities registered in the National Vulnerability Database. The results are promising for the determination of severity by the use of the description since significant correlations were found.

Assessment of Vulnerability Severity using Text Mining

Software1 vulnerabilities are closely associated with information systems security, a major and critical field in todays technology. Vulnerabilities constitute a constant and increasing threat for various aspects of everyday life, especially for safety and economy, since the social impact from the problems that they cause is complicated and often unpredictable. Although there is an entire research branch in software engineering that deals with the identification and elimination of vulnerabilities, the growing complexity of software products and the variability of software production procedures are factors contributing to the ongoing occurrence of vulnerabilities, Hence, another area that is being developed in parallel focuses on the study and management of the vulnerabilities that have already been reported and registered in databases. The information contained in such databases includes, a textual description and a number of metrics related to vulnerabilities. The purpose of this paper is to investigate to what extend the assessment of the vulnerability severity can be inferred directly from the corresponding textual description, or in other words, to examine the informative power of the description with respect to the vulnerability severity. For this purpose, text mining techniques, i.e. text analysis and three different classification methods (decision trees, neural networks and support vector machines) were employed. The application of text mining to a sample of 70,678 vulnerabilities from a public data source shows that the description itself is a reliable and highly accurate source of information for vulnerability prioritization.

Is the Market Value of Software Vendors Affected by Software Vulnerability Announcements

Nowadays, information security constitutes an urgent issue for businesses and researchers. The security vulnerabilities existing in computer systems are sources of different problems. An indirect and emerging issue, regarding the economic consequences of the vulnerabilities, is the impact of software vulnerability announcements to the stock price of the responsible software vendors. The scope of this paper is the study of the stock market reaction when vulnerability announcements occur and the correlation analysis between the impact of these events and vulnerability severity according to scoring systems. To find the impact to the stock market, the well-established in economics event study methodology was used. The dataset in this research was collected from the US-CERT (United States Computer Emergency Readiness Team) website, consisting of year’s 2014 records while the total number of vulnerability announcement events is 75. The results show a slight but not statistically significant negative impact of such events to the stock price of the corresponding firms.

A multi-target approach to estimate software vulnerability characteristics and severity scores

Abstract Software vulnerabilities constitute a great risk for the IT community. The specification of the vulnerability characteristics is a crucial procedure, since the characteristics are used as input for a plethora of vulnerability scoring systems. Currently, the determination of the specific characteristics -that represent each vulnerability- is a process that is performed manually by the IT security experts. However, the vulnerability description can be very informative and useful to predict vulnerability characteristics. The primary goal of this research is the enhancement, the acceleration and the support of the manual procedure of the vulnerability characteristic assignment. To achieve this goal, a model, which combines texts analysis and multi-target classification techniques was developed. This model estimates the vulnerability characteristics and subsequently, calculates the vulnerability severity scores from the predicted characteristics. To perform the present research, a dataset that contains 99,091 records from a large -publicly available- vulnerability database was used. The results are encouraging, since they show accuracy in the prediction of the vulnerability characteristics and scores.

Hypertrophic cardiomyopathy involving the right ventricular apex

A 19-year-old woman with hypertrophic cardiomyopathy (HCM) was referred for clinical assessment. She had no dyspnea, chest pain, syncope or family history of sudden death. The patient’s blood pressure was 100/60 mmHg, and a grade 3/6 to 4/6 systolic ejection murmur was present at the apex. Her 59-year-old mother also had HCM. An electrocardiogram showed diffuse T wave inversion. Maximum left ventricular (LV) wall thickness, as assessed by echocardiography, was 35 mm, and the Doppler-estimated LV outflow gradient at rest was 32 mmHg. The patient had a marked reduction in systolic blood pressure during upright exercise, while no episodes of nonsustained ventricular tachycardia were detected on a 48 h electrocardiogram. Cardiac magnetic resonance imaging showed increased thickness of the septum (39.3 mm) and the apex of the right ventricle, as well as massive delayed enhancement at the hypertrophied septum and apex. Based on the extreme LV hypertrophy and the abnormal blood pressure response during exercise, cardioverter defibrillator implantation was recommended for primary prevention of sudden death. HCM involving the right ventricular apex is rare, and cardiac magnetic resonance imaging is the imaging modality of choice for diagnosis. Four-chamber gradient echo sequence (Figure 1A), short-axis, T1-weighted spin echo sequence (Figure 1B) and four-chamber delayed enhancement imaging (Figure 1C) showed increased thickness of the septum and the apex of the right ventricle, as well as massive enhancement (bright signal) at the hypertrophied septum and apex. Figure 1) Increased thickness of septum and the apex of the right ventricle (RV) shown by four-chamber gradient echo sequence (A), short-axis, T1-weighted spin echo sequence (B) and four-chamber delayed enhancement imaging, demonstrating massive enhancement at ...