The below shown left ventricular pressure-volume (PV) loop is seen in& x20; – - INI-CET EXAM -2025

INI-CET EXAM -2025

Applied Physiology

Hard

Appeared in: INI-CET EXAM -2025

Explanation

The dashed PV loop demonstrates a higher peak systolic pressure and a larger stroke volume (indicated by the loop's increased height and width).
Crucially, the end-systolic volume is lower (the top-left corner of the loop has shifted to the left), while the end-diastolic volume (the bottom-right corner) is unchanged.
This combination of increased ejection and pressure generation at a constant preload is the classic definition of increased myocardial contractility (inotropy).
The heart is pumping more forcefully and efficiently, ejecting a greater fraction of its end-diastolic volume.

Option B: Increased venous return would increase the preload. This would cause the end-diastolic volume to increase, shifting the entire right side of the PV loop to the right. The image shows no change in end-diastolic volume.
Option C: Increased peripheral vascular resistance (afterload) makes it harder for the ventricle to eject blood. This would lead to a decrease in stroke volume (a narrower loop) and an increase in end-systolic volume (the top-left corner shifts right). This is the opposite of what is shown.
Option D: Increased aortic compliance means the aorta is more 'stretchy,' which would actually decrease the afterload. This would result in a lower peak systolic pressure, making the PV loop shorter (less tall), not taller as shown in the image.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Interpretation of Left Ventricular Pressure-Volume (PV) Loops as background academic context rather than a clinical decision trigger.
Understanding PV loops is crucial for interpreting the effects of cardiac medications. Positive inotropic agents like dobutamine or digoxin increase contractility and would produce the change seen in the image.
This concept is vital in managing patients in intensive care. Nurses monitor hemodynamic parameters that reflect these changes to assess cardiac function and response to therapy.
What if the loop shifted down and to the right, becoming wider? This would indicate decreased contractility and increased preload, a classic sign of decompensated systolic heart failure, where the heart is weak and dilated.

How to Approach the Question

First, identify the axes of the graph: LV Pressure (Y-axis) and LV Volume (X-axis).
Analyze the baseline loop (solid line) to understand the four phases: filling, isovolumetric contraction, ejection, and isovolumetric relaxation.
Compare the changed loop (dashed line) to the baseline. Systematically check the four corners of the loop:
Check the bottom-right corner (point B): This is the End-Diastolic Volume (EDV), which reflects preload. Note if it has shifted right (increased preload) or left (decreased preload).
Check the top-left corner (point C/C'): This is the End-Systolic Volume (ESV). Note if it has shifted left (increased ejection/contractility) or right (decreased ejection/increased afterload).
Check the height of the loop: This reflects peak systolic pressure. An increase suggests higher pressure generation.

Concept Tested & Keywords

Concept Tested: Interpretation of Left Ventricular Pressure-Volume (PV) Loops
Stem keywords: left ventricular pressure-volume (PV) loop
Lead-in keywords: seen in
Clinical cues: The key visual cues are the increased height (pressure) and width (stroke volume) of the loop, with a leftward shift of the isovolumetric relaxation phase.

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