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A Review of Automatic Cardiac Segmentation using Deep Learning and Deformable Models
Published in Kayvan Najarian, Delaram Kahrobaei, Enrique Domínguez, Reza Soroushmehr, Artificial Intelligence in Healthcare and Medicine, 2022
Behnam Rahmatikaregar, Shahram Shirani, Zahra Keshavarz-Motamed
The cardiac cycle is defined as a sequence of alternating contractions and relaxations of the atria and ventricles in order to pump blood throughout the body. This cycle starts at the beginning of one heartbeat and ends at the start of the next. Each cardiac cycle has a diastolic phase (also called diastole) and a systolic phase (also called systole). Diastole occurs when the heart muscles relax, and the chambers are able to fill with blood. Systole occurs when the ventricles contract, pushing blood out of the right and left ventricles into the lungs and the rest of the body, respectively. Since manual delineation of ventricle contours in all cardiac phases is not possible, physicians focus only on end-diastole and end-systole phases for assessment of the cardiovascular system.
AI-Based Approach for Person Identification Using ECG Biometric
Published in Gaurav Jaswal, Vivek Kanhangad, Raghavendra Ramachandra, AI and Deep Learning in Biometric Security, 2021
Amit Kaul, A.S. Arora, Sushil Chauhan
It is basically a two-stage pump with its pumping action initiated by an electrical stimulus provided by the sinoatrial (SA) node (natural pacemaker of heart). The pulse produced by the SA node results in contraction of atria. The action potential generated propagates through atria, and on reaching atrioventricular (AV) node is delayed before being transmitted to the ventricles. This entire process known as cardiac cycle is composed of relaxation of ventricles for filling of blood (diastole) and contraction of ventricles for pumping the blood out of heart to pulmonary artery and aorta (systole). The contraction of so many cells at one time creates a mass electrical signal that can be detected by electrodes placed on the surface of person’s chest or his extremities. ECG or EKG is a graphic recording or display of these time-varying voltages produced by heart during the cardiac cycle. Depending upon placement of electrodes, 12 lead configurations can be obtained, three limb leads (Lead I, Lead II, and Lead III), three augmented leads (avR, avL, and avF), and six chest leads (V1, V2, V3, V4, V5, and V6). A typical ECG waveform is depicted in Figure 6.2.
Biomedical Sensors and Data Acquisition
Published in Rajarshi Gupta, Dwaipayan Biswas, Health Monitoring Systems, 2019
Each cardiac cycle is considered to comprise of two periods, viz., systole, representing the contraction or depolarization of cardiac chambers, and diastole, representing the relaxation or repolarization of cardiac chambers. Generation of ECG has already been briefly stated in Section 2.3.1. The PCG consists of four major components I, II, III, and IV, also named as S1, S2, S3, and S4. Out of these, S1 and S2 are generated due to valve closure, have the largest intensity, and are audible as ‘lub’ and ‘dub’, respectively. The first heart sound S1 is observed between closing of mitral (and bicuspid) valve and opening of aortic (and pulmonary) valve. The second heart sound (S2) is audible between the exactly opposite events, i.e., opening of aortic (and pulmonary) valves and closing of tricuspid (and bicuspid) valves. S3 and S4 are with comparatively dull and weak in intensity, observed in children and certain adults, and not related to valve activity.
Cardiac cycle timing intervals in university varsity athletes
Published in European Journal of Sport Science, 2023
Jyotpal Singh, Chase J. Ellingson, Cody A. Ellingson, Parker Scott, J. Patrick Neary
The analysis of the cardiac signal collected at the sternum has been reported elsewhere (Neary et al., 2011; Singh, Ellingson, et al., 2022). Briefly, an in-house, independent (proprietary) algorithm (LLA Technologies Inc) assessed the extracting cardiac features, and all noise signals were removed from the analysis. The data were collected at 500 Hz and processed with a 1st order Butterworth bandpass filter with a low cut-off frequency of 1 Hz and high cut-off frequency of 30 Hz. Fiducial points of the cardiac cycle included the following: mitral valve closure (MVC), aortic valve opening (AVO), aortic twist (ATT), aortic systole, REP, aortic valve closure (AVC), ventricular untwisting, mitral valve opening (MVO). These fiducial points translated to temporal features, being diastole (MVC − MVO timing), systole (AVO − AVC timing), IVCT (MVC − AVO), IVRT (AVC − MVO), atrial systole to mitral valve closure (AS to MVC), mitral valve open to E wave (MVO to E), and end of rapid ejection (REP). Heart rate (AVOn + 1 − AVOn) was calculated in beats per minute. Twist force (TF), or the magnitude of the cardiac contraction acceleration (milligravity, mG) at the sternum, was used to assess contractility (Singh, Bhagaloo, et al., 2022), and AS was used to assess atrial contractility (Neary et al., 2011).
Cardiac cycle timing and contractility following acute sport-related concussion
Published in Research in Sports Medicine, 2022
Jyotpal Singh, Chase J. Ellingson, Cody A. Ellingson, Parker Scott, J. Patrick Neary
The analysis of the cardiac signal collected at the sternum has been reported elsewhere (Singh et al., 2021). Briefly, an in-house, independent (proprietary) algorithm (LLA Technologies Inc.) assessed the extracting cardiac features, and all noise signals were removed from the signal. Specifically, data were collected at 500 Hz and a first-order Butterworth bandpass filter with a low cut-off frequency of 1 Hz and a high cut-off frequency of 30 Hz filter was applied to smooth the signal and adjust for the baseline wandering. Fiducial points of the cardiac cycle included the following: mitral valve closure (MVC), aortic valve opening (AVO), aortic twist (ATT), aortic systole, REP, aortic valve closure (AVC), ventricular untwisting, and mitral valve opening (MVO). These fiducial points translated to temporal features, being diastole (MVC − MVO timing), systole (AVO − AVC timing), IVCT (MVC − AVO), IVRT (AVC − MVO), atrial systole to mitral valve closure (AS to MVC), mitral valve open to E wave (MVO to E), and end of rapid ejection (REP). Heart rate (AVOn+1 − AVOn) was calculated in beats per minute. Twist force (TF), or the magnitude of the cardiac contraction acceleration (milligravity, mG) at the sternum, was used to assess contractility, and AS was used to assess atrial contractility (Neary et al., 2011).
Therapeutic options for functional mitral regurgitation in chronic heart failure
Published in Expert Review of Medical Devices, 2018
Judith E. Lowry, Stephan Fichtlscherer, Klaus K. Witte
A fully percutaneous mitral valve replacement might provide a possible solution for patients with severe MR especially in the setting of mixed etiologies in people with prohibitive comorbidities. The major challenge over percutaneous aortic valve replacement is the great anatomical complexity and variability of the mitral valve including the subvalvular apparatus, and also the mobility of the mitral valve structure during the cardiac cycle. Due to difficulties of achieving access and positioning of a large valve, most systems to date have been transapical, but in the longer term, the greater morbidity associated with this route over a transfemoral approach is likely to be a limiting factor. A large number of TMVR systems are in clinical and preclinical trials [60], but with an average 30-day mortality of 23% (with half of these occurring periprocedurally) it is clear that a trial comparing sham with a TMVR approach is still far in the future.