Detection of the valvular split within the second heart sound using the reassigned smoothed pseudo Wigner–Ville distribution

BACKGROUND: In this paper, we developed a novel algorithm to detect the valvular split between the aortic and pulmonary components in the second heart sound which is a valuable medical information. METHODS: The algorithm is based on the Reassigned smoothed pseudo Wigner–Ville distribution which is a modified time–frequency distribution of the Wigner–Ville distribution. A preprocessing amplitude recovery procedure is carried out on the analysed heart sound to improve the readability of the time–frequency representation. The simulated S2 heart sounds were generated by an overlapping frequency modulated chirp–based model at different valvular split durations. RESULTS: Simulated and real heart sounds are processed to highlight the performance of the proposed approach. The algorithm is also validated on real heart sounds of the LGB–IRCM (Laboratoire de Génie biomédical–Institut de recherches cliniques de Montréal) cardiac valve database. The A2–P2 valvular split is accurately detected by processing the obtained RSPWVD representations for both simulated and real data

Hemodynamic Changes following Aortic Valve Bypass: A Mathematical Approach

Aortic valve bypass (AVB) has been shown to be a viable solution for patients with severe aortic stenosis (AS). Under this circumstance, the left ventricle (LV) has a double outlet. The objective was to develop a mathematical model capable of evaluating the hemodynamic performance following the AVB surgery. A mathematical model that captures the interaction between LV, AS, arterial system, and AVB was developed. This model uses a limited number of parameters that all can be non-invasively measured using patient data. The model was validated using in vivo data from the literature. The model was used to determine the effect of different AVB and AS configurations on flow proportion and pressure of the aortic valve and the AVB. Results showed that the AVB leads to a significant reduction in transvalvular pressure gradient. The percentage of flow through the AVB can range from 55.47% to 69.43% following AVB with a severe AS. LV stroke work was also significantly reduced following the AVB surgery and reached a value of around 1.2 J for several AS severities. Findings of this study suggest: 1) the AVB leads to a significant reduction in transvalvular pressure gradients; 2) flow distribution between the AS and the AVB is significantly affected by the conduit valve size; 3) the AVB leads to a significant reduction in LV stroke work; and 4) hemodynamic performance variations can be estimated using the model.Fonds quebecois de la recherche sur la nature et les technologies (176048

Telemedical transport layer security based platform for cardiac arrhythmia classification using quadratic time-frequency analysis of HRV signal

International audienceThe heart rate variability signal is a valuable tool for cardiovascular system diagnostics. Processing this signal detects arrhythmia during long-term cardiac monitoring. It is also analyzed to recognize abnormalities within the autonomic nervous system. Processing this signal helps in detecting various pathologies, such as atrial fibrillation (AF), supraventricular tachycardia (SVT), and congestive heart failure (CHF). As a beneficial alternative to the commonly used HRV spectrum analysis, quadratic time-frequency analysis of HRV signals could be helpful in heart pathology detection. Indeed, in this study, we have created a client-server paradigm deployed as a telemedical platform for real-time remote monitoring of the cardiovascular function in patients suffering from arrhythmia. This platform detects arrhythmia in real-time by deploying time-frequency analysis, feature extraction, feature selection, and classification of Heart Rate Variability (HRV) signals. We gathered all these functionalities in a Graphical User Interface (GUI) in addition to data acquisition. As a client, a Raspberry Pi Zero ensures data acquisition and connects to a server over TCP/IP that involves a 4G/3G connection encrypted through the transport layer security (TLS). This telemedical tool continuously monitors the heart rate variability. In the case of an alarm, medical professionals may immediately interact with their patients in the hospital or at home

Simulated LV stroke work.

<p>(A) Pre-AVB surgery for a severe AS (EOA = 0.7 cm²), (B) post-AVB surgery with a conduit valve size of 19 mm and a conduit size of 18mm, (C) LV stroke work variations with and without AVB for different AS severities. The values are averaged over the all configurations for AVB in terms of conduit and valves sizes simulated in this study.</p

Summarized cardiovascular parameters used to simulate all cases.

<p>*Maximum error in computed ratio between AS and AVB flow rates from sensitivity analysis in response to independent variation (±30%) in each parameter</p><p>Summarized cardiovascular parameters used to simulate all cases.</p

Simulated left ventricle and aorta pressures and flow distribution.

<p>(A) Severe AS (EOA = 0.7 cm²) & AVB (conduit valve size: 19 mm, conduit size: 18mm), (B) severe AS (EOA = 0.7 cm²) & AVB (conduit valve size: 19 mm, conduit size: 26mm). Stroke volume, heart rate and cardiac output are 75 ml, 70 beats/min and 5.2 l/min, respectively.</p

Simulated left ventricle and aorta pressures.

<p>(A) Healthy (No AS & No AVB), (B) severe AS (EOA = 0.7 cm²) & No AVB. Stroke volume, heart rate and cardiac output are 75 ml, 70 beats/min and 5.2 l/min, respectively.</p

Schematic diagrams.

<p>(A) Electrical representation, (B) schematic representation of the lumped parameter model used to simulate left-sided heart in presence of aortic stenosis and/or apico-aortic conduit (please see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0123000#pone.0123000.t001" target="_blank">Table 1</a> for all other parameters used in the lumped parameter model).</p

Computed AS and AVB flow rate ratio in the presence of fixed severe AS (EOA = 0.7 cm2).

<p>*Relative error in computed flow rates through native valve with EOA of 0.7 cm² and AVB with combinations of 18–19, 20–21 and 22–23, compared to the results reported by Stauffer et al. (2011) are 4.49%, 2.34% and 0.11%, respectively. AV: aortic valve; AVB: aortic valve bypass</p><p>Stroke volume, heart rate and cardiac output are 75 ml, 70 beats/min and 5.2 l/min, respectively. AV: aortic valve, AVB: aortic valve bypass</p><p>Computed AS and AVB flow rate ratio in the presence of fixed severe AS (EOA = 0.7 cm2).</p