Med Quizzes

Left-to-Right Shunts

Mouse: Drag each finding into the correct category. Keyboard: 1–9 to pick up, A–D to place. ? hotkeys / cheatsheet

Keyboard Shortcuts

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

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Left-to-Right Shunts Cheatsheet

Key Concept: L-to-R shunts cause pulmonary overcirculation and worsen as PVR drops at 4–8 weeks. VSD = holosystolic murmur. PDA = continuous murmur + bounding pulses. Eisenmenger = irreversible PVR elevation → shunt reversal → cyanosis. Fetal circulation = high PVR, R→L shunts.

Category	Key Features
VSD Pathophysiology	L→R shunt through interventricular septum Holosystolic murmur at left lower sternal border Palpable thrill if large shunt volume Symptoms worsen at 4–8 weeks as PVR falls and shunt volume increases Pulmonary edema → rales + respiratory distress Hepatomegaly from right heart backup Diuretics + caloric supplementation until surgical repair
PVR & Shunt Timing	Fetal PVR is HIGH → little L-to-R shunting immediately after birth PVR falls over weeks → shunt volume increases → symptoms appear at 4–8 weeks Persistently high PVR (Eisenmenger) → shunt reversal R→L → cyanosis Eisenmenger physiology is irreversible — early repair prevents it Diaphoresis with feeds — high sympathetic tone from heart failure
PDA Pathophysiology	L→R shunt through ductus arteriosus Continuous (machinery) murmur best heard at left infraclavicular area Bounding peripheral pulses + widened pulse pressure Disproportionately affects premature infants (ductus fails to close) Indomethacin (COX inhibitor) promotes closure in premature infants Surgical or catheter ligation if medical therapy fails
Normal Fetal Circulation	Fetal circulation: high PVR + low SVR → R→L shunts via PDA + foramen ovale Oxygenated blood from placenta via umbilical vein → ductus venosus → IVC Fetal lungs deflated — minimal pulmonary blood flow At birth: lungs inflate → PVR falls dramatically Ductus arteriosus closes functionally (oxygen ↑ + PGE2 ↓) Foramen ovale closes functionally at birth; anatomic closure by 3–6 months

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Left-to-Right Shunts

Findings Bank

A VSD Pathophysiology

B PVR & Shunt Timing

C PDA Pathophysiology

D Normal Fetal Circulation