Learning Objectives

• Differentiate stenotic vs. regurgitant valvular lesions on Pressure-Volume loops.
• Identify the loss of isovolumetric phases in regurgitant pathologies.
• Correlate chamber pressure changes (e.g., LA vs. LV) with specific valvular dysfunctions.
• Understand the impact of chronic valvular disease on ventricular compliance and stroke volume.

Aortic Stenosis (AS)

In Aortic Stenosis, the LV must generate massive pressure to overcome the narrow valvular orifice.

• Pressure Changes: Significant ↑ LV systolic pressure to maintain ejection. A high-pressure gradient exists between the LV and the aorta.
• Loop Shifts: Increased ESV (ventricle cannot empty fully) and ↓ Stroke Volume (SV).
• Compliance: Chronic pressure overload leads to concentric hypertrophy, which ↓ affects ventricular compliance, leading to ↑ EDP for any given volume.

Aortic Regurgitation (AR)

In Aortic Regurgitation, blood leaks back into the left ventricle from the aorta during diastole.

• Isovolumetric Phases: No true isovolumetric phases; the ventricle is either filling from the aorta/LA or ejecting into both.
• Loop Shifts: Massive ↑ EDV and ↑ SV (total SV = forward flow + backward flow).
• Clinical Findings: Large pulse pressure and loss of the dicrotic notch on the aortic pressure tracing.

Mitral Stenosis (MS)

In Mitral Stenosis, impaired flow from the LA to the LV restricts ventricular filling.

• Pressure Changes: Significant ↑ LA pressure. During diastole, LA pressure > LV pressure.
• Loop Shifts: Primary change is ↓ EDV due to impaired filling.
• Outcome: Subsequent ↓ SV and ↓ ESV (the ventricle starts from a smaller volume).

Mitral Regurgitation (MR)

In Mitral Regurgitation, blood is ejected into both the low-pressure LA and the high-pressure aorta during systole.

• Isovolumetric Phases: No true isovolumetric phases; blood leaks into the LA as soon as the LV starts contracting.
• Loop Shifts: ↓ ESV (due to ↓ resistance/afterload into the LA) and ↑ EDV (due to increased LA volume returning to the LV).
• Atrial Findings: Results in a tall V-wave on JVP or LA pressure tracings due to regurgitant volume entering the atrium against a closed (but leaky) valve.

Activity