Predictors of exercise capacity in patients with atrial correction of transposition of great arteries.

OBJECTIVES: To examine the relationship of clinical, biochemical and imaging parameters to maximum oxygen uptake in patients after atrial correction of transposition of great arteries. BACKGROUND: Exercise tolerance is a key determinant of quality of life in patients with adult congenital heart disease. It is determined by a large scale of factors often different from general cardiology. METHODS: 86 consecutive patients after Senning correction of TGA were subjected to clinical and echocardiographic examination, Holter monitoring, blood tests of NT-proBNP, MRI of the heart and exercise test. Parameters of these examinations were correlated to VO2 max. RESULTS: The average age of patients was 28±3.5 years. The average systemic right ventricular function determined by MRI was 51.9±7.9 %. The average NT-proBPN was 124.3±23.6 ng/l, VO2 max. 31.7±6.5    ml/kg/min and the heart rate reserve 106±24 /min. Neither systemic right ventricular systolic function nor   NT-proBPN predicted VO2 max., whereas the heart rate reserve did (p=0.003). CONCLUSION: An inability to increase heart rate during exercise noted in a considerable number of patients after atrial switch of TGA caused a decreased exercise tolerance. It is not solely the global systolic function of either ventricle that influences the exercise performance, rather it is the ability to increase heart rate and overall cardiac output appropriately (Tab. 3, Fig. 6, Ref. 28).

Outcome of resynchronization therapy on superficial and endocardial electrophysiological findings.

Cardiac resynchronization therapy (CRT) has proven efficacious in the treatment of patients with heart failure and dyssynchronous activation. Currently, we select suitable CRT candidates based on the QRS complex duration (QRSd) and morphology with left bundle branch block being the optimal substrate for resynchronization. To improve CRT response rates, recommendations emphasize attention to electrical parameters both before implant and after it. Therefore, we decided to study activation times before and after CRT on the body surface potential maps (BSPM) and to compare thus obtained results with data from electroanatomical mapping using the CARTO system. Total of 21 CRT recipients with symptomatic heart failure (NYHA II-IV), sinus rhythm, and QRSd >/=150 ms and 7 healthy controls were studied. The maximum QRSd and the longest and shortest activation times (ATmax and ATmin) were set in the BSPM maps and their locations on the chest were compared with CARTO derived time interval and site of the latest (LATmax) and earliest (LATmin) ventricular activation. In CRT patients, all these parameters were measured during both spontaneous rhythm and biventricular pacing (BVP) and compared with the findings during the spontaneous sinus rhythm in the healthy controls. QRSd was 169.7+/-12.1 ms during spontaneous rhythm in the CRT group and 104.3+/-10.2 ms after CRT (p<0.01). In the control group the QRSd was significantly shorter: 95.1+/-5.6 ms (p<0.01). There was a good correlation between LATmin(CARTO) and ATmin(BSPM). Both LATmin and ATmin were shorter in the control group (LATmin(CARTO) 24.8+/-7.1 ms and ATmin(BSPM) 29.6+/-11.3 ms, NS) than in CRT group (LATmin(CARTO) was 48.1+/-6.8 ms and ATmin(BSPM) 51.6+/-10.1 ms, NS). BVP produced shortening compared to the spontaneous rhythm of CRT recipients (LATmin(CARTO) 31.6+/-5.3 ms and ATmin(BSPM) 35.2+/-12.6 ms; p<0.01 spontaneous rhythm versus BVP). ATmax exhibited greater differences between both methods with higher values in BSPM: in the control group LATmax(CARTO) was 72.0+/-4.1 ms and ATmax (BSPM) 92.5+/-9.4 ms (p<0.01), in the CRT candidates LATmax(CARTO) reached only 106.1+/-6.8 ms whereas ATmax(BSPM) 146.0+/-12.1 ms (p<0.05), and BVP paced rhythm in CRT group produced improvement with LATmax(CARTO) 92.2+/-7.1 ms and ATmax(BSPM) 130.9+/-11.0 ms (p<0.01 before and during BVP). With regard to the propagation of ATmin and ATmax on the body surface, earliest activation projected most often frontally in all 3 groups, whereas projection of ATmax on the body surface was more variable. Our results suggest that compared to invasive electroanatomical mapping BSPM reflects well time of the earliest activation, however provides longer time-intervals for sites of late activation. Projection of both early and late activated regions of the heart on the body surface is more variable than expected, very likely due to changed LV geometry and interposed tissues between the heart and superficial ECG electrode.

Evaluation of health care related web resources based on web citation analysis and other quality criteria.

Automatic system for ranking of educational health care related web resources based on quality criteria was developed. Automatic retrieval of new web resources from well-known directories followed by their automatic evaluation is a keystone of the system. The system provides this information: a) location of the resource and its author, b) number of back links to the resource, c) checks presence of electronic labels of quality. Currently the system encompasses more than 500 links to educational web resources divided into 47 medical specialities. The resources in all categories are ranked according to their link popularity, the electronic labels of quality are presented. History of link popularity is recorded and might be displayed at every resource. There are 2 language editions. The system operates automatically, the editors check and correct the retrieved values. The described system adds to webcite indexing criteria for objective evaluation of quality of webpages. It is useful for the selection of optimum education resources in health care.

Long-term retention of knowledge after a distance course in medical informatics at Charles University Prague.

BACKGROUND: Distance education is instructional delivery that does not constrain the student to be physically present in the same location as the instructor. The electronic distance learning called e-learning has evolved with the development of computer technologies and electronic communication. PURPOSE: Before setting the distance way of teaching as a standard part of medical schools' curricula, the impact of number of factors on the effectiveness of this way of teaching should be considered. METHODS: A group of 38 students went through a distance course of medical informatics. The course consisted of 10 lessons. At the end of the course the students sat for a final test that contained 60 multiple-choice test questions. There was always one correct answer. Time limit for test completion was 60 minutes. After 12 months, 31 students from the original group sat for the same test. The topics of the course were not repeated in the meantime. The students were not aware that their knowledge would be tested after 1 year. RESULTS: The average retention of knowledge expressed as a percentage of the students' performance in the first test was 66.8%. The knowledge retention correlated significantly with the statement "I liked the online course more than the classroom course" and positively with the number of hours spent with the computer weekly. CONCLUSIONS: Retention of knowledge after the electronic distance course after 12 months is close to 67%. Other results indicate that we can expect better retention of knowledge from independent, responsible, and positively motivated students who can easily operate information technologies.