Summary : This figure illustrates the left atrial (LA) pressure-volume relationship during the cardiac cycle, showing both time-course traces and a pressure-volume loop, with key phases of atrial function annotated and correlated with the ECG. line plot and loop diagram: # Panel A: LA Pressure and Volume Traces • Top trace: LA Pressure (y-axis, arbitrary units) over time. • Middle trace: LA Volume (y-axis, arbitrary units) over time. • Bottom trace: ECG waveform for temporal reference. • X-axis: Cardiac cycle phases, with systole and diastole labeled; diastole further subdivided into E, D, and A phases. • Five phases are color-coded and numbered: – (1) Atrial filling (red) – (2) Passive emptying (green) – (3) Diastasis (black) – (4) Active emptying (blue) – (5) Atrial relaxation (gray) • Vertical dashed lines demarcate transitions between phases. # Panel B: LA Pressure-Volume Loop • X-axis: LA Volume (arbitrary units). • Y-axis: LA Pressure (arbitrary units). • The loop is traced in a counterclockwise direction, with arrows indicating the sequence. • The same five phases (1–5) are color-coded as in Panel A. • The loop is divided into two segments: A-Loop (phases 1, 3, 4, 5) and V-Loop (phase 2). # Design Encodings : • Distinct colors for each phase (red, green, black, blue, gray). • Arrows on the loop indicate the direction of the cardiac cycle. • ECG trace provides timing reference for the pressure and volume changes. # Analysis : • The LA pressure and volume traces show cyclical changes corresponding to atrial filling, emptying, and relaxation. • The pressure-volume loop visually summarizes the dynamic relationship between LA pressure and volume, with distinct segments for passive and active phases. • The figure highlights the temporal coordination between atrial events and the ECG, emphasizing the mechanical and electrical coupling in the cardiac cycle.

This physiological signal diagram illustrates the temporal correlation between mechanical and electrical cardiac activity over a 5-second interval. The figure consists of four vertically stacked, time-synchronized plots sharing a common horizontal axis (Time in Seconds). From top to bottom, the waveforms represent: 1) Accelerometer data (Accel in m/s²), 2) Gyroscope data (Gyro in degrees/second), 3) Normalized Amplitude (representing the ensemble averaging of the motion sensors), and 4) Electrocardiogram (ECG in mV). A vertical red box highlights a specific epoch around the 1-second mark, demonstrating that the mechanical peaks in the seismocardiogram (SCG) and gyrocardiogram (GCG) signals correspond directly with the R-wave peak of the ECG. This visualization is used to demonstrate the efficacy of multi-axis MEMS sensors in capturing cardiac-induced chest vibrations and their synchronization with the heart's electrical cycle, which is essential for non-invasive heart rate monitoring and hemodynamic assessment.

A three-panel physiological waveform diagram illustrating the temporal relationship between cardiac hemodynamics and motion sensor signals. The upper panel displays a synchronized Electrocardiogram (ECG), Left Ventricular Pressure (PLV), and Aortic Pressure (PAO). A vertical arrow highlights the P wave, while a vertical line marks the R wave, corresponding to the onset of ventricular systole where PLV rises and eventually equilibrates with PAO. The middle panel shows the total composite accelerometer (Acc Tot) signal, with a dotted ellipse identifying the systolic tension onset signal (STOS) and a dashed ellipse highlighting the diastolic acceleration component. The lower panel displays the total angular velocity (Gyro Tot) signal measured in degrees per second, with a dotted box marking the systolic gyroscopic activity and a dashed box outlining the diastolic phase. These waveforms demonstrate that mechanical motion signals from accelerometers and gyroscopes correlate with specific phases of the cardiac cycle, such as systolic contraction and diastolic filling, as defined by the concurrent pressure and ECG traces.

Summary : This figure shows a pressure–volume loop for the left ventricle, illustrating how ventricular volume and pressure change during the cardiac cycle, with key phases and valve events annotated. The isovolumetric relaxation and contraction periods are highlighted, and systolic/diastolic blood pressures are marked. pressure–volume loop diagram: # Title & Axes : • No explicit title on the figure, but the legend describes it as a "Pressure–volume loop demonstrating changes in ventricular volume during filling and ejection with corresponding changes in intracavity pressure." • X-axis: "Left ventricular volume (mL)" with tick marks at 0, 20, 40, 60, 80, 100, 120, 140, 160. • Y-axis: "Left ventricular pressure (mmHg)" with tick marks at 0, 20, 40, 60, 80, 100, 120, 140. • Additional axis labels: "Left ventricular end-diastolic pressure" (blue, left), "End-diastolic volume" (blue, bottom right), "Stroke volume" (black, bottom center). # Phases & Events : • Isovolumetric relaxation: vertical line at low volume, pressure drops, labeled. • Diastolic filling: horizontal line at low pressure, volume increases, labeled. • Isovolumetric contraction: vertical line at high volume, pressure rises, labeled. • Ventricular ejection: curved line, volume decreases as pressure peaks and falls, labeled. • Valve events: – Mitral valve opens (bottom left corner, low pressure/volume). – Mitral valve closes (bottom right corner, high volume/low pressure). – Aortic valve opens (top right corner, high volume/high pressure). – Aortic valve closes (top left corner, low volume/high pressure). # Blood Pressure Markers : • Systolic BP: horizontal dashed blue line at ~120 mmHg. • Diastolic BP: horizontal dashed blue line at ~80 mmHg. # Design Encodings : • Black solid lines for the loop. • Blue dashed lines for blood pressure markers. • Blue text for end-diastolic volume/pressure. • Labeled arrows for direction of phases and valve events. # Analysis : • The loop traces the cardiac cycle, starting at low pressure/volume (end-systolic), filling during diastole, rising sharply during isovolumetric contraction, ejecting blood during ventricular ejection, and dropping pressure during isovolumetric relaxation. • Systolic and diastolic blood pressures are marked, showing the pressure range during ejection. • The width of the loop (horizontal distance) represents stroke volume. • The figure clearly distinguishes the four main phases and the timing of valve openings/closings, providing a comprehensive view of ventricular mechanics during a heartbeat.

A three-panel physiological waveform diagram illustrating the temporal relationship between cardiac hemodynamics and motion sensor signals. The upper panel displays a synchronized Electrocardiogram (ECG), Left Ventricular Pressure (PLV), and Aortic Pressure (PAO). A vertical arrow highlights the P wave, while a vertical line marks the R wave, corresponding to the onset of ventricular systole where PLV rises and eventually equilibrates with PAO. The middle panel shows the total composite accelerometer (Acc Tot) signal, with a dotted ellipse identifying the systolic tension onset signal (STOS) and a dashed ellipse highlighting the diastolic acceleration component. The lower panel displays the total angular velocity (Gyro Tot) signal measured in degrees per second, with a dotted box marking the systolic gyroscopic activity and a dashed box outlining the diastolic phase. These waveforms demonstrate that mechanical motion signals from accelerometers and gyroscopes correlate with specific phases of the cardiac cycle, such as systolic contraction and diastolic filling, as defined by the concurrent pressure and ECG traces.

This physiological signal diagram illustrates the temporal synchronization of cardiac mechanical and electrical events over a single heart cycle. The visualization includes seven aligned waveforms: (a) a standard lead ECG with labeled P-Q-R-S-T complexes; (b) Left Ventricular (LV) rotation mechanics showing apical (purple), basal (brown), and net LV twist (black) in degrees; (c) corresponding rotation rates in degrees per second; (d-e) Seismocardiogram (SCG) representing linear (KLin) and rotational (KRot) kinetic energy in millijoules (mJ); and (f-g) Ballistocardiogram (BCG) also representing KLin and KRot energy. A vertical dashed line indicates Aortic Valve Closure (AVC). The diagram highlights key pathophysiological relationships: SCG energy peaks bimodal, occurring during the ejection phase (pre-AVC) and early diastole (post-AVC), while BCG energy peaks appear almost exclusively during the diastolic phase (post-AVC). This chart serves as an educational tool for understanding the relationship between electrical conduction, myocardial rotational mechanics, and the kinetic energy generated by cardiac micro-accelerations and body displacements.

Summary : This figure shows a pressure–volume loop for the left ventricle, illustrating how ventricular volume and pressure change during the cardiac cycle, with key phases and valve events annotated. The isovolumetric relaxation and contraction periods are highlighted, and systolic/diastolic blood pressures are marked. pressure–volume loop diagram: # Title & Axes : • No explicit title on the figure, but the legend describes it as a "Pressure–volume loop demonstrating changes in ventricular volume during filling and ejection with corresponding changes in intracavity pressure." • X-axis: "Left ventricular volume (mL)" with tick marks at 0, 20, 40, 60, 80, 100, 120, 140, 160. • Y-axis: "Left ventricular pressure (mmHg)" with tick marks at 0, 20, 40, 60, 80, 100, 120, 140. • Additional axis labels: "Left ventricular end-diastolic pressure" (blue, left), "End-diastolic volume" (blue, bottom right), "Stroke volume" (black, bottom center). # Phases & Events : • Isovolumetric relaxation: vertical line at low volume, pressure drops, labeled. • Diastolic filling: horizontal line at low pressure, volume increases, labeled. • Isovolumetric contraction: vertical line at high volume, pressure rises, labeled. • Ventricular ejection: curved line, volume decreases as pressure peaks and falls, labeled. • Valve events: – Mitral valve opens (bottom left corner, low pressure/volume). – Mitral valve closes (bottom right corner, high volume/low pressure). – Aortic valve opens (top right corner, high volume/high pressure). – Aortic valve closes (top left corner, low volume/high pressure). # Blood Pressure Markers : • Systolic BP: horizontal dashed blue line at ~120 mmHg. • Diastolic BP: horizontal dashed blue line at ~80 mmHg. # Design Encodings : • Black solid lines for the loop. • Blue dashed lines for blood pressure markers. • Blue text for end-diastolic volume/pressure. • Labeled arrows for direction of phases and valve events. # Analysis : • The loop traces the cardiac cycle, starting at low pressure/volume (end-systolic), filling during diastole, rising sharply during isovolumetric contraction, ejecting blood during ventricular ejection, and dropping pressure during isovolumetric relaxation. • Systolic and diastolic blood pressures are marked, showing the pressure range during ejection. • The width of the loop (horizontal distance) represents stroke volume. • The figure clearly distinguishes the four main phases and the timing of valve openings/closings, providing a comprehensive view of ventricular mechanics during a heartbeat.