Search results for "Cardiac cycle"
showing 7 items of 27 documents
Left-Ventricle Segmentation of SPECT Images of Rats
2015
Single-photon emission computed tomography (SPECT) imaging of the heart is helpful to quantify the left-ventricular ejection fraction and study myocardial perfusion scans. However, these evaluations require a 3-D segmentation of the left-ventricular wall on each phase of the cardiac cycle. This paper presents a fast and interactive graph cut method for 3-D segmentation of the left ventricle (LV) of rats in SPECT images. The method is carried out in three steps. First, 3-D sampling of the LV cavity is made in a spherical-cylindrical coordinate system. Then, a graph-cut-based energy minimization procedure provides delineation of the myocardium centerline surface. From there, it is possible to…
Echocardiographic diagnosis of Candida endocarditis of the tricuspid valve and of the right atrium in a young infant.
1983
Systemic candidiasis developed in a seven-week-old premature baby after 6 weeks treatment with antibiotics for suspected septicemia. At that time the echocardiogram showed a dense layer of echoes posteriorly to the anterior tricuspid leaflet during atrial systole. The diagnosis of Candida endocarditis with vegetations on the tricuspid valve and with right atrial thrombus secondary to the Candida infection was verified by autopsy.
Rapid changes in bodily and neural states affect learning
2018
Declarative memories consist of the past events and factual information that can be recalled. One of the most popular experimental paradigms used in studying long-term memory formation is classical conditioning. Trace conditioning is a hippocampus-dependent task where two separate sensory stimuli are presented in contingency but with a temporal gap between. In trace eyeblink conditioning a conditioned stimulus, usually a tone, is presented with a short silent period followed by an airpuff to the eye. In the beginning of the learning process the behavioral response to the airpuff is naturally a blink of an eye. After repeated trials the subject learns to shut the eyelid after perceiving the …
Non-invasive visualisation of coronary atherosclerosis: state-of-art.
2007
Coronary artery disease remains the leading cause of death in the Western world. Non-invasive coronary artery imaging challenges any diagnostic modality because the coronary arteries are small and tortuous, whereas cardiac contraction and respiration cause motion artifacts. Therefore, non-invasive coronary imaging requires high spatial and temporal resolution. This review discusses the feasible applications in coronary imaging of magnetic resonance imaging and multi-slice computed tomography (MSCT), which are currently the only non-invasive diagnostic modalities for direct coronary atherosclerosis imaging. Particular attention and focus is devoted to the potential indications and clinical i…
Shot placement within cardiac cycle in junior elite rifle shooters
2007
Abstract Objectives This study examined the timing of the trigger pull in relation to the cardiac cycle during skilled precision shooting. Methods Electrocardiogram was recorded from 20 junior level competitive air-rifle shooters in two separate sessions. The testing was conducted at an indoor shooting range using an optoelectronic shooting system. The experimental task was to fire a shot in the standing position at a distance of 10 m from the target. Results The results showed that the junior level shooters fired more often during the phase of 10–15% of the R wave-to-R wave (R–R) interval. With regards to the accuracy of performance, there was not any optimal location for triggering in the…
Physiological parameters measurements in a cardiac cycle via a combo PPG-ECG system
2015
In this paper, we present an innovative way to measure some physiological parameters (such as the pre-ejection period, the pulse transit time, the blood pressure) in a cardiac cycle. A combo PPG-ECG system has been developed and employed to extract both the ECG signal from standard limb leads and simultaneously the photoplethysmography signal from the wrist and the forearm, to calculate the pre-ejection period. This system represents an easy and non-invasive technique to determine these biomedical parameters without using expensive impedance cardiography equipment.
The effects of heart rate variability and cardiac cycle time on learning in trace eye-blink conditioning
2017
Ärsykkeen sydämen sykkeeseen ajastamisella on huomattu olevan yhteyttä sensoriseen havainnointiin ja korkeampaan kognitiiviseen prosessointiin, kun sykevälivaihtelu (HRV)puolestaan on yhdistetty tarkkaavaisuuteen. Tässä tutkimuksessa tarkasteltiin sykevälivaihtelun sekä ärsykkeen sydämen sykkeeseen ajastamisen yhteyksiä oppimiseen. Koehenkilöt osallistuivat silmäniskuehdollistumiskokeeseen, missä ärsykkeet oli ajastettu joko sydämen sykkeen systoliseen tai diastoliseen vaiheeseen. HRV:n ja EEG:n mittaaminen aloitettiin viisi minuuttia ennen kokeen alkua ja sitä jatkettiin viisi minuuttia kokeen loppumisen jälkeen. Tutkimuksessa tarkasteltiin kuutta HRV-muuttujaa: sykevälin keskiarvo (MRR), …