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.

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 multi-panel line graph illustrating the physiological mechanics of an in vitro cardiac loading device (CLD) used to simulate ventricular pressure-volume relationships. The visualization consists of four vertically aligned time-series plots depicting a cyclical cardiac simulator test. The top panel shows heart chamber pressure oscillating between 0 and 100 mmHg. The second panel displays ventricular balloon (VB) pressure, reaching peaks of approximately 80 mmHg. The third panel tracks reservoir balloon (RB) pressure, which fluctuates between 10 and 14 mmHg. The bottom panel indicates the status of an electronic check valve (ECV) as a binary voltage (0V for closed, 5V for open). Vertical dashed lines (labeled 1, 2, and 3) correlate specific phases: (1) ECV opening when VB pressure exceeds afterload, leading to VB emptying and RB filling; (2) VB refilling when VB pressure drops below RB pressure; and (3) ECV closure upon completion of refilling. This diagram is utilized in cardiovascular physiology research to validate cardiac cycle simulation for isolated heart preparations.

Clinical photograph demonstrating the auscultatory method of blood pressure measurement in a research or clinical setting. The image is divided into two highlighted sections: (a) shows a Welch Allyn DS66 aneroid sphygmomanometer, featuring a circular gauge with a black face and white numerical scale, connected to a black rubber inflation bulb held by a researcher. (b) displays a dark blue reusable adult blood pressure cuff (Welch Allyn) secured around the subject's left upper arm. A stethoscope chest piece is placed over the brachial artery beneath the distal edge of the cuff to detect Korotkoff sounds. The researcher is shown wearing the stethoscope and manually inflating the cuff. This visual illustrates the gold standard for non-invasive blood pressure monitoring used to validate novel pulse wave sensors and algorithms. Key educational concepts include proper cuff placement, manual sphygmomanometry technique, and clinical cardiovascular assessment.

This clinical photograph demonstrates the manual assessment of blood pressure using a sphygmomanometer and an acoustic stethoscope. The image shows a healthcare provider's hand stabilizing a metal stethoscope diaphragm over the patient's antecubital fossa, specifically positioned over the brachial artery to auscultate Korotkoff sounds. A brown fabric inflatable cuff is securely wrapped around the patient's upper arm, proximal to the stethoscope placement. The patient's arm is resting on a white hospital bedsheet with printed black text. Key anatomical landmarks include the inner elbow (antecubital space) and the distal upper arm. This visual serves as an educational aid for clinical skills training, illustrating the correct placement of instruments for non-invasive blood pressure (NIBP) measurement. The medical specialty is general medicine or nursing, focusing on basic physiological monitoring and clinical examination techniques.

This clinical photograph captures a healthcare interaction in a field medical setting, specifically a cholera treatment center. The image shows a healthcare provider performing a non-invasive blood pressure measurement on a seated adult female patient. The clinician, wearing nitrile gloves and green scrubs, has positioned an aneroid sphygmomanometer cuff on the patient's left upper arm. A visible blue-faced manual pressure gauge is attached to the cuff. The provider is simultaneously using a stethoscope (partially visible) for auscultation of Korotkoff sounds to determine systolic and diastolic values. This scene illustrates vital sign monitoring as a critical component of clinical assessment and hemodynamic stabilization in infectious disease management, particularly for monitoring dehydration levels in cholera patients. The setting emphasizes healthcare delivery in resource-limited or humanitarian crisis environments.

This composite educational illustration combines an anatomical diagram of the human heart with a diagnostic Electrocardiogram (ECG) tracing to demonstrate cardiac physiology. On the left, a coronal cross-section of the heart identifies the Aorta, Right Atrium, Left Atrium, Right Ventricle, and Left Ventricle. The right side features a detailed ECG waveform analysis set against a standard measurement grid (1 square = 0.04 sec / 0.1 mV). The tracing identifies key electrophysiological components: the P wave (atrial depolarization), QRS complex (ventricular depolarization), and T wave (ventricular repolarization). Critical diagnostic intervals and segments are explicitly labeled, including the PR interval, PR segment, QRS interval, ST segment, ST interval, QT interval, and the RR interval (representing the heart rate). This comparison chart and pathophysiology diagram serve as an introductory resource for understanding the correlation between cardiac anatomy and the electrical signals recorded during a cardiac cycle, suitable for basic to intermediate medical education.

This diagnostic image is an electrocardiogram (ECG)-gated cardiac computed tomography (CCT) cine mode reconstruction captured during the diastolic phase of the cardiac cycle. The cross-sectional view displays the four major cardiac chambers and associated structures labeled as follows: Aorta (Ao), Right Atrium (RA), Right Ventricle (RV), and Left Ventricle (LV). A prominent white arrow indicates a flap-type rupture in the wall between the non-coronary cusp of the aorta and the right atrium. This visual evidence confirms a ruptured sinus of Valsalva aneurysm (SVA), showing an abnormal communication where the flap opens into the right atrium during diastole. The spatial arrangement shows the dilated aorta adjacent to a widened right atrium, with the right ventricle and thick-walled left ventricle positioned inferiorly. This image illustrates the pathophysiology of an intracardiac shunt causing a left-to-right flow, relevant for cardiologists and radiologists studying complex congenital or acquired structural heart defects and their presentation in cross-sectional imaging.

**Modality:** Transthoracic Echocardiogram (TTE). **View:** Parasternal Long-Axis (PLAX) view. **Anatomical Landmarks:** The image displays the left ventricle (LV), left atrium (LA), and the aortic root (Ao). The descending thoracic aorta is partially visible in the far field. **Observed Pathology:** There is a prominent, dilated coronary sinus (CS) visualized in cross-section within the atrioventricular groove, posterior to the left atrium and anterior to the descending aorta. **Visual Features:** The coronary sinus appears as a distinct, enlarged circular anechoic structure. The surrounding cardiac chambers (LV, LA, Ao) maintain their relative anatomical positions. An electrocardiogram (ECG) lead trace is visible at the bottom of the frame, indicating the timing within the cardiac cycle. **Clinical Context/Differentiating Features:** A dilated coronary sinus is a characteristic finding often associated with increased right atrial pressure or persistent left superior vena cava (PLSVC). This image serves as a diagnostic reference for identifying venous anomalies or volume/pressure overload in the right heart system via standard parasternal imaging.