Med Quizzes

VSD Pathophysiology

Mouse: Drag each finding into the correct stage of VSD progression. Keyboard: 1–9 or click to pick up, A–D to place, Tab/Enter to navigate zones. ? hotkeys / cheatsheet

Keyboard Shortcuts

Key	Action
1 - 9	Pick up finding by position in bank
Click	Pick up / deselect finding
A - D	Place held finding into zone
Tab	Cycle through zones (when holding)
Enter	Drop into focused zone
Bksp	Return held finding to bank
Esc	Cancel / close modal
/	Toggle cheatsheet
?	Toggle this help

Press ? or Esc to close

VSD Pathophysiology Cheatsheet

Stage	Hemodynamic Changes	Consequences
In Utero	Equal RV/LV pressures	No hemodynamic effect
Postnatal Transition	PVR SVR	LR shunting begins Holosystolic murmur at LLSB Palpable systolic thrill
Infancy	Pulmonary overcirculation	LA/LV volume overload LV dilation Enlarged left heart on CXR HF signs ( WOB, FTT)
Late Childhood	Pulm. artery thickening PVR	RL shunt reversal Eisenmenger syndrome Cyanosis

PVR vs SVR — Key Concepts

Pressure ≠ Resistance: PVR and SVR are resistance values, not pressures. Pressure = Resistance × Flow (like Ohm's law: V = IR).
Why PVR drops at birth: The lungs inflate and fill with air, causing the pulmonary vasculature to dilate dramatically. This is a structural change, not driven by the VSD.
Why LR shunting occurs: After birth, SVR > PVR. The left ventricle works against SVR; the right ventricle works against (lower) PVR. This pressure gradient drives blood leftright through the VSD.
Less blood out of left heart? No — the left heart actually receives more blood (from pulmonary overcirculation), so it volume-overloads. Cardiac output is maintained; this is high-output heart failure.

Pathophysiology Chains

LR Path

PVRbirth LR Shuntpostnatal Pulm. Overcirculationinfancy LA Preloadinfancy LV Dilationinfancy Enlarged Left Heart on CXRinfancy

Eisenmenger

Pulm. Artery Thickeninglate childhood PVRlate childhood Shunt Reversallate childhood Eisenmengerlate childhood Cyanosislate childhood

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VSD Pathophysiology

Finding Bank

A In Utero

B Postnatal Transition

C Infancy

D Late Childhood