Source / episode info
- **Episode:**106
- **Title:**Divine Intervention Episode 106 – ABIM/Medicine ITE/USMLE Step 3 Review Series 6 (Cardio 2).
- **Published:**2019-05-27
- Source:Episode page
One-liner
This episode provides a deep dive into advanced cardiology topics, covering the hemodynamic differences between Hypertrophic Cardiomyopathy (HCM) and Aortic Stenosis, differentiating murmurs (MR vs MVP), diagnosing pericarditis, and mastering the complex physical exam findings of constrictive versus restrictive heart disease using JVP analysis.
High-yield summary
- Hypertrophic Cardiomyopathy (HCM): The murmur is caused by dynamic Left Ventricular Outflow Tract Obstruction (LVOTO) due to Systolic Anterior Motion (SAM) of the mitral valve. Increasing LV volume (e.g., squatting, handgrip) decreases the obstruction and makes the murmur softer.
- Aortic Stenosis (AS): The murmur is fixed by a narrowed valve. Increasing LV volume increases flow through the stenotic valve and makes the murmur louder.
- Pericarditis: Classic triad includes pleuritic chest pain, worse when lying back/improving when leaning forward, and diffuse ST elevation with PR segment depression on EKG. The friction rub disappears when holding breath (differentiating from pleurisy).
- Constrictive Pericarditis vs. Cardiac Tamponade: Both cause equalization of diastolic pressures in all four chambers. Differentiation relies on JVP: Constriction shows a rapid X descent; Tamponade shows an absent X descent.
- JVP Waves: The 'A' wave reflects right atrial contraction; the 'C' wave reflects tricuspid valve closure/RV contraction; the 'X' descent reflects RV relaxation and RA pressure drop.
Learning objectives
- Differentiate the hemodynamic principles underlying murmurs in HCM versus Aortic Stenosis using physical maneuvers (Valsalva, squatting).
- Recognize the classic clinical and EKG findings associated with acute pericarditis and its differential diagnosis from pleurisy/myocarditis.
- Master the diagnostic criteria for constrictive pericarditis, including characteristic JVP waveforms (rapid X descent) and imaging signs (calcification).
- Understand the pathophysiology of cardiac tamponade, particularly the resulting equalization of diastolic pressures.
- Apply knowledge of preload changes to predict how murmurs in MR, MVP, and HCM will change.
Board exam buzzwords