Cardiac Anatomy, Human Anatomy, USMLE Step 1 - Full Vignette with Extended Explanations скачать в хорошем качестве

Cardiac Anatomy, Human Anatomy, USMLE Step 1 - Full Vignette with Extended Explanations

A 37-year-old man with cardiac risk factors presents after exertion with chest pressure radiating to the right shoulder and jaw, diaphoresis, hypoxemia, jugular venous distention, tachycardia, and hypotension. ECG shows inferior ST elevations with reciprocal changes, and point-of-care echo reveals right ventricular dysfunction. Before giving any vasodilator, what critical diagnostic step should be prioritized to prevent worsening hypotension in this scenario involving a classic coronary territory? VIDEO INFO Category: Cardiac Anatomy, Human Anatomy, USMLE Step 1 Difficulty: Moderate - Intermediate level - Requires solid foundational knowledge Question Type: Clinical Pitfalls Case Type: Common Scenario Explore more ways to learn on this and other topics by going to https://endlessmedical.academy/auth?h... QUESTION A 37-year-old man with hyperlipidemia, benign prostatic hyperplasia, and a remote history of monomorphic ventricular tachycardia presents with 45 minutes of substernal pressure radiating to the right shoulder and jaw that began while carrying groceries up two flights of stairs. He drinks alcohol socially once or twice weekly and does not smoke.... OPTIONS A. Obtain immediate right-sided precordial leads (V3R-V4R at minimum) in the ED to detect ST elevation consistent with right ventricular infarction before administering nitrates, which can critically drop preload in proximal RCA-territory injury. B. Administer standard sublingual nitroglycerin now and reassess blood pressure after each dose; additional ECG leads can wait until the catheterization laboratory is activated and transport begins. C. Record posterior leads V7-V9 first because posterior involvement is usually the dominant concern in inferior infarction; right-sided leads can be obtained later if hypotension occurs after initial vasodilator therapy. D. Start a nitroglycerin infusion at 10-20 mcg/min for rapid pain control to reduce afterload while preparing for primary PCI; right-sided leads add little to initial triage and can be added during transfer. CORRECT ANSWER A. Obtain immediate right-sided precordial leads (V3R-V4R at minimum) in the ED to detect ST elevation consistent with right ventricular infarction before administering nitrates, which can critically drop preload in proximal RCA-territory injury. EXPLANATION Inferior STEMI with reciprocal changes should immediately raise concern for a proximal right coronary artery culprit and potential right ventricular involvement. Nitrates reduce preload and can precipitate severe hypotension in RV infarction because the right ventricle is preload dependent. The single fastest diagnostic maneuver before any vasodilator is to record right-sided precordial leads, especially V3R-V4R, which have high sensitivity early after symptom onset to detect ST-segment elevation consistent with RV infarction. In this vignette, clues include ST elevation in II, III, aVF with ST elevation in V1, clear lungs with elevated jugular venous pressure, a thin hypokinetic RV free wall on point-of-care echo, and low oxygen saturation improving with supplemental oxygen. Obtaining right-sided leads in the ED directly informs whether nitrates are contraindicated and whether initial therapy should emphasize cautious fluids and avoidance of preload-reducing agents, in line with contemporary ACS guidance. The distractors all commit the pitfall the question targets. Administering sublingual nitroglycerin before determining RV involvement risks precipitous hypotension in a preload-dependent state.... --------------------------------------------------- Our cases and questions come from the https://EndlessMedical.Academy quiz engine - multi-model platform. Each question and explanation is forged by consensus between multiple top AI models (GPT, Claude, Grok, etc.), with automated web searches for the latest research and verified references. Calculations (e.g. eGFR, dosages) are checked via code execution to eliminate errors, and all references are reviewed by several AIs to minimize hallucinations. Important note: This material is entirely AI-generated and has not been verified by human experts; despite stringent consensus checks, perfect accuracy cannot be guaranteed. Exercise caution - always corroborate the content with trusted references or qualified professionals, and never apply information from this book to patient care or clinical decisions without independent verification. Clinicians already rely on AI and online tools - myself included - so treat this book as an additional focused aid, not a replacement for proper medical education. Visit https://endlessmedical.academy for more AI-supported resources and cases. This material can not be treated as medical advice. May contain errors. ---------------------------------------------------