Source / episode info

• **Episode:**595
• **Title:**DIP Ep 595: USMLE Step 2/3 Rapid Review Series 121
• **Published:**2025-04-23
• Source:Episode page

One-liner

This episode provides a rapid review of high-yield associations in congenital heart defects (e.g., Marfan, Down syndrome), the pathophysiology and complications of polycythemia vera (PV) and secondary polycythemia (COPD), and systemic principles like Poiseuille's Law and acquired coagulopathies.

High-yield summary

• Lithium Toxicity: Associated with Epstein's anomaly, which involves downward displacement of the tricuspid valve leaflets and often presents with associated ASD/PFO defects.
• Polycythemia Etiology: The most common cause is hypoxemia from pulmonary disease (e.g., COPD), leading to EPO release; however, malignancy (RCC, HCC) or congenital heart defects can also stimulate EPO production perinatopically.
• Polycythemia Vera (PV): This is a myeloproliferative disorder characterized by EPO-independent red blood cell proliferation (JAK2 mutation). Its complications include hyperviscosity syndrome, thrombosis, gout, and secondary hypertension.
• Vascular Principles: Increased blood viscosity increases total peripheral resistance (Poiseuille's Law), leading to increased afterload on the left ventricle, which causes concentric hypertrophy and eventually heart failure with preserved ejection fraction (HFpEF).
• PV Coagulopathy: Chronic thrombosis consumes clotting factors, resulting in an acquired deficiency of von Willebrand Factor.
• Syndromic Associations: Strong associations must be remembered: Down syndrome -> Endocardial cushion defect; Marfan Syndrome -> Mitral valve prolapse and aortic aneurysm/dissection.

Learning objectives

• Identify the specific cardiac associations for various genetic syndromes (e.g., Down syndrome, Marfan).
• Differentiate between secondary polycythemia (hypoxemic) and primary myeloproliferative disorders (PV).
• Explain the pathophysiology of hyperviscosity syndrome in Polycythemia Vera, including its impact on coagulation and circulation.
• Apply Poiseuille's Law principles to understand how increased blood viscosity affects systemic vascular resistance and cardiac workload.
• Recognize the key management steps for PV, including phlebotomy and antiplatelet therapy.